Emission Factor Documentation for AP-42

Section 11.7

CERAMIC PRODUCTS MANUFACTURING

Final Report

For U. S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Emission Factor and Inventory Group

EPA Contract 68-D2-0159

Work Assignment No. III-01

MRI Project No. 4603-01

June 1996
Emission Factor Documentation for AP-42

Section 11.7

CERAMIC PRODUCTS MANUFACTURING

Final Report

For U. S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Emission Factor and Inventory Group

Research Triangle Park, NC 27711

Attn: Mr. Ron Myers (MD-14)

Emission Factor and Inventory Group

EPA Contract 68-D2-0159

Work Assignment No. III-01

MRI Project No. 4603-01

June 1996
NOTICE

The information in this document has been funded wholly or in part by the United States

Environmental Protection Agency under Contract No. 68-D2-0159 to Midwest Research Institute. It

has been reviewed by the Office of Air Quality Planning and Standards, U. S. Environmental

Protection Agency, and has been approved for publication. Mention of trade names or commercial

products does not constitute endorsement or recommendation for use.

ii
PREFACE

This report was prepared by Midwest Research Institute (MRI) for the Office of Air Quality

Planning and Standards (OAQPS), U. S. Environmental Protection Agency (EPA), under Contract

No. 68-D2-0159, Work Assignment No. III-01. Mr. Ron Myers was the requester of the work.

Approved for:

MIDWEST RESEARCH INSTITUTE

Roy Neulicht

Program Manager

Environmental Engineering Department

Jeff Shular

Director, Environmental Engineering

Department

June, 1995

iii
iv
TABLE OF CONTENTS

Page

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

2. INDUSTRY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.1 INDUSTRY CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2 PROCESS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2.2.1 Raw Material Procurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2.2.2 Beneficiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9

2.2.3 Mixing .................................................. 2-10

2.2.4 Forming ................................................. 2-10

2.2.5 Green Machining ........................................... 2-11

2.2.6 Drying .................................................. 2-11

2.2.7 Presinter Thermal Processing .................................. 2-12

2.2.8 Glazing ................................................. 2-12

2.2.9 Firing ................................................... 2-12

2.2.10 Final Processing ........................................... 2-15

2.3 EMISSIONS .................................................... 2-16

2.4 EMISSION CONTROL TECHNOLOGY ................................ 2-16

3. GENERAL DATA REVIEW AND ANALYSIS PROCEDURES . . . . . . . . . . . . . . . . . . . 3-1

3.1 LITERATURE SEARCH AND SCREENING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2 DATA QUALITY RATING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.3 EMISSION FACTOR QUALITY RATING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . 3-3

4. AP-42 SECTION DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2 REVIEW OF SPECIFIC DATA SETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2.1 Reference 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2.2 Reference 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2.3 Reference 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4.2.4 Reference 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4.2.5 Reference 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.2.6 Reference 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.2.7 Reference 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.2.8 Reference 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.2.9 Reference 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.2.10 Reference 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

4.2.11 Reference 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

4.2.12 Reference 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

4.2.13 Reference 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

4.2.14 Reference 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2.15 Reference 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

v
TABLE OF CONTENTS (continued)

Page

4.2.16 Reference 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2.17 Reference 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2.18 Reference 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2.19 Reference 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.2.20 Reference 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.2.21 Reference 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.2.22 Reference 23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.2.23 Reference 24 ............................................. 4-10

4.2.24 Reference 25 ............................................. 4-10

4.2.25 Reference 26 ............................................. 4-10

4.2.26 Reference 27 ............................................. 4-10

4.2.27 Reference 28 ............................................. 4-11

4.3 DEVELOPMENT OF CANDIDATE EMISSION FACTORS .................. 4-11

4.3.1 Filterable PM ............................................. 4-11

4.3.2 Volatile Organic Compounds .................................. 4-19

4.3.3 Carbon Monoxide .......................................... 4-19

4.3.4 Carbon Dioxide ............................................ 4-19

4.3.5 Nitrogen Oxides ........................................... 4-20

4.3.6 Sulfur Dioxide ............................................ 4-20

4.3.7 Hydrogen Fluoride ......................................... 4-20

4.3.8 Fluoride ................................................. 4-20

4.3.9 Lead ................................................... 4-21

4.4 SUMMARY OF CHANGES TO AP-42 SECTION ......................... 4-21

4.4.1 Section Narrative ........................................... 4-21

4.4.2 Emission Factors ........................................... 4-21

5. PROPOSED AP-42 SECTION 11.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

vi
LIST OF FIGURES

Figure Page

2-1 Process flow diagram for ceramic products manufacturing . . . . . . . . . . . . . . . . . . . 2-5

2-2 Miscellaneous ceramic products manufacturing processes and equipment . . . . . . . . 2-6

LIST OF TABLES

Table Page

2-1 STANDARD INDUSTRIAL CLASSIFICATION CODES FOR CERAMIC

PRODUCTS MANUFACTURING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2-2 LOCATION OF CERAMIC MANUFACTURERS IN 1987 . . . . . . . . . . . . . . . . . 2-2

2-3 LOCATION OF CERAMIC MANUFACTURERS IN 1987 WITH 20

OR MORE EMPLOYEES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2-4 COMPOSITIONS OF COMMERCIAL GLAZES ......................... 2-13

2-5 TYPICAL FIRING TEMPERATURES OF CERAMICS .................... 2-14

2-6 FACTORS THAT REDUCE HF EMISSIONS ........................... 2-17

4-1 SUMMARY OF EMISSION FACTORS FROM REFERENCE 1 . . . . . . . . . . . . . 4-2

4-2 SUMMARY OF TEST DATA FOR CERAMIC KILNS .................... 4-12

4-3 SUMMARY OF TEST DATA FOR OTHER CERAMIC PRODUCTS

MANUFACTURING SOURCES .................................... 4-14

4-4 EMISSION FACTOR SUMMARY FOR NATURAL GAS-FIRED CERAMIC KILNS 4-16

4-5 EMISSION FACTOR SUMMARY FOR MISCELLANEOUS CERAMIC

PRODUCTS MANUFACTURING SOURCES .......................... 4-17

vii
EMISSION FACTOR DOCUMENTATION FOR AP-42 SECTION 11.7

Ceramic Products Manufacturing

1. INTRODUCTION

The document Compilation of Air Pollutant Emission Factors (AP-42) has been published by

the U. S. Environmental Protection Agency (EPA) since 1972. Supplements to AP-42 have been

routinely published to add new emission source categories and to update existing emission factors.

AP-42 is routinely updated by EPA to respond to new emission factor needs of EPA, State and local

air pollution control programs, and industry.

An emission factor is a representative value that attempts to relate the quantity of a pollutant

released to the atmosphere with an activity associated with the release of that pollutant. Emission

factors usually are expressed as the weight of pollutant divided by the unit weight, volume, distance,

or duration of the activity that emits the pollutant. The emission factors presented in AP-42 may be

appropriate to use in a number of situations, such as making source-specific emission estimates for

areawide inventories for dispersion modeling, developing control strategies, screening sources for

compliance purposes, establishing operating permit fees, and making permit applicability

determinations. The purpose of this report is to provide background information from test reports and

other information to support revisions to AP-42 Section 8.7, Ceramic Clay Manufacturing.

This background report consists of five sections. Section 1 includes the introduction to the

report. Section 2 gives a description of the ceramic clay manufacturing industry. It includes a

characterization of the industry, a description of the different process operations, a characterization of

emission sources and pollutants emitted, and a description of the technology used to control emissions

resulting from these sources. Section 3 is a review of emission data collection (and emission

measurement) procedures. It describes the literature search, the screening of emission data reports, and

the quality rating system for both emission data and emission factors. Section 4 details how the

revised AP-42 section was developed. It includes the review of specific data sets, a description of

how candidate emission factors were developed, and a summary of changes to the AP-42 section.

Section 5 presents the AP-42 Section 11.7, Ceramic Products Manufacturing.

1-1
2. INDUSTRY DESCRIPTION

2.1 INDUSTRY CHARACTERIZATION1-3

Ceramics are defined as a class of inorganic, nonmetallic solids that are subject to high

temperature in manufacture and/or use. The most common ceramics are composed of oxides, carbides,

and nitrides. Silicides, borides, phosphides, tellurides, and selenides also comprise ceramics. Ceramic

processing generally involves high temperatures, and the resulting materials are heat resistant or

refractory.

Ceramic manufacturing is classified under several Standard Industrial Classification (SIC)

codes. These SIC codes are listed in Table 2-1.

In addition, ceramic fiber is classified under SIC 3299, nonmetallic mineral products, not

TABLE 2-1. STANDARD INDUSTRIAL CLASSIFICATION

CODES FOR CERAMIC PRODUCTS MANUFACTURING

SIC Title

3253 Ceramic wall and floor tile

3261 Vitreous plumbing fixtures

3262 Vitreous china table and kitchenware

3263 Semivitreous table and kitchenware

3264 Porcelain electrical supplies

3269 Pottery products, not elsewhere classified

elsewhere classified.

In 1987, more than 1,100 ceramic manufacturing facilities classified under these SIC codes

were operating in the United States. The majority of these facilities were relatively small operations

engaged in the manufacture of pottery products. However, there were more than 300 ceramic

manufacturing facilities with at least 20 employees. Table 2-2 lists the total number of ceramics

manufacturers by State and SIC code, and Table 2-3 lists the number of manufacturers with at least

20 employees in 1987. In terms of number of facilities, the leading ceramic manufacturing States in

1987 were California, Ohio, Texas, Pennsylvania, New York, and New Jersey.

Traditional ceramics refers to ceramic products that are produced from unrefined clay and

combinations of refined clay and powdered or granulated nonplastic minerals. Often, traditional

ceramics is used to refer to ceramics in which the clay content exceeds 20 percent. The general

classifications of traditional ceramics are described below.

Pottery is sometimes used as a generic term for ceramics that contain clay and are not used for

structural, technical, or refractory purposes.

2-1
TABLE 2-2. LOCATION OF CERAMIC MANUFACTURERS IN 1987a

State

SIC Code

3253 3261 3262 3263 3264 3269 Total

Alabama 3 2 6 11

Arizona 1 1

California 20 12 4 12 21 149 218

Colorado 4 11 15

Connecticut 1 1

Florida 6 37 43

Georgia 4 4 2 10

Illinois 4 5 13 22

Indiana 3 3

Kentucky 3 1 14 18

Maryland 2 2

Michigan 4 18 22

Mississippi 2 1 3

New Jersey 4 5 1 13 21 44

New York 5 5 13 32 55

North Carolina 2 2 22 26

Ohio 13 6 5 5 9 38 76

Oklahoma 1 1 5 7

Oregon 27 27

Pennsylvania 3 3 2 4 12 35 59

South Carolina 1 2 3

Tennessee 4 4 15 23

Texas 15 8 38 61

West Virginia 1 3 4

Wisconsin 1 1 15 17

Other States 29 13 14 23 19 258 356

Total 114 65 34 44 116 754 1,127

Value of shipments,

$ million

717.4 790.6 298.4 93.0 714.2 519.7 2,243

a

Reference 2.

2-2
TABLE 2-3. LOCATION OF CERAMIC MANUFACTURERS IN 1987

WITH 20 OR MORE EMPLOYEESa

State

SIC Code

3253 3261 3262 3263 3264 3269 Total

Alabama 2 1 1 4

Arizona 1 1

California 8 6 1 6 8 31 60

Colorado 1 2 3

Connecticut 1 1

Florida 3 2 5

Georgia 2 2 1 5

Illinois 2 2 5 9

Indiana 3 3

Kentucky 3 1 6 10

Maryland 1 1

Michigan 2 2 4

Mississippi 2 1 3

New Jersey 1 4 1 10 7 23

New York 1 2 9 3 15

North Carolina 2 1 2 5

Ohio 8 5 4 3 7 14 41

Oklahoma 1 1 2 4

Oregon 1 1

Pennsylvania 3 2 2 3 8 6 24

South Carolina 1 2 3

Tennessee 2 4 3 9

Texas 8 6 4 18

West Virginia 1 2 3

Wisconsin 1 1 4 6

Other States 5 4 2 6 6 20 43

Total 51 40 14 18 66 115 304

a

Reference 2.

2-3
Whiteware refers to ceramic ware that is white, ivory, or light gray in color after firing.

Whiteware is further classified as earthenware, stoneware, chinaware, porcelain, and technical

ceramics.

Earthenware is defined as glazed or unglazed nonvitreous (porous) clay-based ceramic ware.

Applications for earthenware include artware, kitchenware, ovenware, tableware, and tile.

Stoneware is vitreous or semivitreous ceramic ware of fine texture, made primarily from

nonrefractory fire clay or some combination of clays, fluxes, and silica that, when fired, has properties

similar to stoneware made from fire clay. Applications for stoneware include artware, chemicalware,

cookware, drainpipe, kitchenware, tableware, and tile.

Chinaware is vitreous ceramic ware of zero or low absorption after firing that is used for

nontechnical applications. Applications for chinaware include artware, ovenware, sanitaryware, and

tableware.

Porcelain is defined as glazed or unglazed vitreous ceramic ware used primarily for technical

purposes. Applications for porcelain include artware, ballmill balls, ballmill liners, chemicalware,

insulators, and tableware.

Technical ceramics include vitreous ceramic whiteware used for such products as electrical

insulation, or for chemical, mechanical, structural, or thermal applications.

Ceramic products that are made from highly refined natural or synthetic compositions and

designed to have special properties are referred to as advanced ceramics. Advance ceramics can be

classified according to application as electrical, magnetic, optical, chemical, thermal, mechanical,

biological, and nuclear.

Most ceramic products are clay-based and are made from a single clay or one or more clays

mixed with mineral modifiers such as quartz and feldspar. The types of commercial clays used for

ceramics are primarily kaolin and ball clay.

2.2 PROCESS DESCRIPTION1,3-5

Figure 2-1 presents a general process flow diagram for ceramic products manufacturing. The

basic steps include raw material procurement, beneficiation, mixing, forming, green machining, drying,

presinter thermal processing, glazing, firing, final processing, and packaging. The following

paragraphs describe these operations in detail. Figure 2-2 shows miscellaneous ceramic products

manufacturing processes and equipment.

2.2.1 Raw Material Procurement

To begin the process, raw materials are transported and stored at the manufacturing facility.

The raw materials used in the manufacture of ceramics range from relatively impure clay materials

mined from natural deposits to ultrahigh purity powders prepared by chemical synthesis. Naturally

occurring raw materials used to manufacture ceramics include silica, sand, quartz, flint, silicates, and

aluminosilicates (e.g., clays and feldspar).

2-4
Figure 2-1. Process flow diagram for ceramic products manufacturing.

2-5
Figure 2-2. Miscellaneous ceramic products manufacturing processes and equipment.4,5

2-6
Figure 2-2. (continued)

2-7
Figure 2-2. (continued)

2-8
2.2.2 Beneficiation

The next step in the process is beneficiation. Although chemically synthesized ceramic

powders also require some beneficiation, the focus of this discussion is on the processes for

beneficiating naturally occurring raw materials. The basic beneficiation processes include

comminution, purification, sizing, classification, calcination, liquid dispersion, and granulation.

Naturally occurring raw materials often undergo some beneficiation at the mining site or at an

intermediate processing facility prior to being transported to the ceramic manufacturing facility.

Comminution entails reducing the particle size of the raw material by crushing, grinding, and

milling or fine grinding. The purpose of comminution is to liberate impurities, break up aggregates,

modify particle morphology and size distribution, facilitate mixing and forming, and produce a more

reactive material for sintering. Primary crushing generally reduces material up to 0.3 meter (m)

(1 foot [ft]) in diameter down to 1 centimeter (cm) (0.40 inch [in.]) in diameter. Secondary crushing

reduces particle size down to approximately 1 millimeter (mm) (0.04 in.) in diameter. Fine grinding

or milling reduces the particle size down to as low as 1.0 micrometer (μm) (4 x 10-5 in.) in diameter.

Ball mills are the most commonly used piece of equipment for milling. However, vibratory mills,

attrition mills, and fluid energy mills also are used. Ball mills consist of closed containers that are

filled with grinding media and rotated to induce a cascading action of the media. Attrition mills are

fixed, closed containers filled with grinding media that is agitated by rotating arms. Vibratory mills

consist of fixed containers lined with a flexible material and filled with grinding media that is vibrated.

Fluid energy mills uses a high velocity fluid such as air, water, or superheated steam to cause the

material particles to impact one another. Crushing and grinding typically are dry processes; milling

may be wet or dry processes. In wet milling, water or alcohol are commonly used as the milling

liquid.

Several procedures are used to purify the ceramic material. Water soluble impurities can be

removed by washing with deionized or distilled water and filtering, and organic solvents may be used

for removing water-insoluble impurities. Acid leaching is sometimes employed to remove metal

contaminants. Magnetic separation is used to extract magnetic impurities from either dry powders or

wet slurries. Froth flotation also is used to separate undesirable materials.

Sizing and classification separate the material into size ranges. Sizing is most often

accomplished using fixed or vibrating screens. Dry screening can be used to sizes down to 44 μm

(0.0017 in., 325 mesh). Dry forced-air sieving and sonic sizing can be used to size dry powders down

to 37 μm (0.0015 in., 400 mesh), and wet sieving can be used for particles down to 25 μm

(0.00098 in., 500 mesh). Classification processes use differences in how particles settle in a liquid

(elutriation) or moving gas stream to separate coarse and fine fractions of ceramic powders. Air

classifiers generally are effective in the range of 420 μm to 37 μm (0.0165 to 0.0015 in., 40 to

400 mesh). However, special air classifiers are available for isolating particles down to 10 μm

(0.00039 in.).

Calcining consists of heating a ceramic material to a temperature well below its melting point

to liberate undesirable gases or other material and to bring about structural transformation to produce

the desired composition and phase product. Calcining typically is carried out in rotary calciners,

heated fluidized beds, or by heating a static bed of ceramic powder in a refractory crucible.

2-9
Liquid dispersion of ceramic powders sometimes is used to make slurries. Slurry processing

facilitates mixing and minimizes particle agglomeration. The primary disadvantage of slurry

processing is that the liquid must be removed prior to firing the ceramic.

Dry powders often are granulated to improve flow, handling, packing, and compaction.

Granulation is accomplished by direct mixing, which consists of introducing a binder solution during

powder mixing, or by spray drying. In spray drying, the ceramic powder in the form of a slurry is

atomized by means of a pressure nozzle or rotary atomizer and sprayed toward the top of the drying

chamber. A descending stream of heated air flowing countercurrent to the spray dries the slurry as

dense, homogeneous, spherical granules, which are collected at the base of the dryer. Spray dryers

generally are gas-fired and operate at temperatures of 110° to 130°C (230° to 270°F).

2.2.3 Mixing

The purpose of mixing or blunging is to combine the constituents of a ceramic powder to

produce a more chemically and physically homogenous material for forming. Pug mills often are used

for mixing ceramic materials. Several processing aids may be added to the ceramic mix during the

mixing stage. Binders and plasticizers are used in dry powder and plastic forming; in slurry

processing, deflocculants, surfactants, and antifoaming agents are added to improve processing.

Liquids also are added in plastic and slurry processing.

Binders are polymers or colloids that are used to impart strength to green or unfired ceramic

bodies. For dry forming and extrusion, binders amount to 3 percent by weight of the ceramic mixture.

Some examples of binders are polyvinyl alcohol and polyethylene glycol.

Plasticizers and lubricants are used with some types of binders. Plasticizers increase the

flexibility of the ceramic mix. Examples include adsorbed water, ethylene glycol, stearic acid, oleic

acid, and glycerine. Lubricants, such as stearic acid and oleic acid, lower frictional forces between

particles and reduce wear on equipment.

Water is the most commonly used liquid in plastic and slurry processing. Organic liquids such

as alcohols may also be used in some cases. Deflocculants also are used in slurry processing to

improve dispersion and dispersion stability. Some examples of deflocculants are monovalent cations

for clay-water slurries or slips, ammonium salts for polar liquids, acids and bases to control pH, and

oleic acid, tartaric acid, benzoic acid, stearic acid, and trichloroacetic acid for oxide powders in

nonpolar liquids. Surfactants are used in slurry processing to aid dispersion, and antifoams are used to

remove trapped gas bubbles from the slurry.

2.2.4 Forming

In the forming step, dry powders, plastic bodies, pastes, or slurries are consolidated and

molded to produce a cohesive body of the desired shape and size. Dry forming consists of the

simultaneous compacting and shaping of dry ceramic powders in a rigid die or flexible mold. Dry

forming can be accomplished by dry pressing, isostatic compaction, and vibratory compaction. In dry

pressing, which is used for forming products that are of relatively uniform thickness and axially

symmetric, ceramic powder with a moisture content of 5 to 15 percent is compacted between plungers

in a die cavity. In isostatic compaction, ceramic powder with a moisture content of 0 to 15 percent is

placed inside a flexible mold, which is then deaired, sealed, and placed in a gas- or liquid-filled

pressurized chamber. Isostatic compaction is used to produce complex shapes such as spark plugs and

2-10
larger shapes that are not easily dry pressed. Vibratory compaction is used for producing irregular

shapes from ungranulated powders.

Plastic molding is accomplished by extrusion, jiggering, or powder injection molding.

Extrusion, which generally is preceded by mixing in a pugmill and deairing in a vacuum chamber,

consists of consolidating plastic material with a moisture content of 12 to 20 percent, forcing it

through a forming die, and ejecting the formed body. Extrusion is used in manufacturing structural

clay products and some refractory products. Jiggering involves shaping a plastic clay body on a

spinning porous plaster mold using a water mist or steam lubricated shaping tool. Jiggering is widely

used in the manufacture of small, simple, axially symmetrical whiteware ceramic such as cookware,

fine china, and electrical porcelain. In powder injection molding, a hot ceramic and binder mixture is

injected into a cooler die, extracted, and deburred. This method is used for making small complex

shapes.

Paste forming consists of applying a thick film of ceramic paste on a substrate. Ceramic

pastes are used for decorating ceramic tableware, and forming capacitors and dielectric layers on rigid

substrates for microelectronics.

Slurry forming of ceramics generally is accomplished using slip casting, gelcasting, or tape

casting. In slip casting, a ceramic slurry, which has a moisture content of 20 to 35 percent, is poured

into a porous mold. Capillary suction of the mold draws the liquid from the mold, thereby

consolidating the cast ceramic material. After a fixed time, the excess slurry is drained, and the cast is

dried. The casting rate can be increased by vacuum casting, heating, or centrifugal casting. Slip

casting is widely used in the manufacture of sinks and other sanitaryware, figurines, porous thermal

insulation, fine china, and structural ceramics with complex shapes. Gelcasting uses in situ

polymerization of organic monomers to produce a gel that binds ceramic particles together into

complex shapes such as turbine rotors. Tape casting consists of forming a thin film of ceramic slurry

of controlled thickness onto a support surface using a knife edge. Tape casting is used to produce thin

ceramic sheets or tape, which can be cut and stacked to form multilayer ceramics for capacitors and

dielectric insulator substrates.

2.2.5 Green Machining

After forming, the ceramic shape often is machined to eliminate rough surfaces and seams or

to modify the shape. The methods used to machine green ceramics include surface grinding to smooth

surfaces, blanking and punching to cut the shape and create holes or cavities, and laminating for

multilayer ceramics.

2.2.6 Drying

After forming, ceramics must be dried. Drying must be carefully controlled to strike a balance

between minimizing drying time and avoiding differential shrinkage, warping, and distortion. The

most commonly used method of drying ceramics is by convection, in which heated air is circulated

around the ceramics. Air drying often is performed in tunnel kilns, which are long furnaces with

drying, firing, and cooling zones. In tunnel kilns, the drying zone typically uses heat recovered from

the cooling zone. Periodic kilns or dryers operating in batch mode also are used. Convection drying

also is carried out in divided tunnel dryers, which include separate sections with independent

temperature and humidity controls. An alternative to air drying is radiation drying in which

microwave or infrared radiation is used to enhance drying.

2-11
2.2.7 Presinter Thermal Processing

Prior to firing, ceramics are often heat-treated at temperatures well below firing temperatures.

The purpose of this thermal processing is to provide additional drying, to vaporize or decompose

organic additives and other impurities, and to remove residual, crystalline, and chemically bound

water. Presinter thermal processing can be applied as a separate step, which is referred to as bisque

firing, or by gradually raising and holding the temperature in several stages.

Organic "burnout" typically occurs at a temperature of approximately half the firing

temperature. Removal of residual liquid is attained at a temperature of approximately 200°C (392°F),

water of crystallization is liberated at approximately 700°C (1290°F), and chemically bound water is

eliminated at approximately 1000°C (1830°F).

2.2.8 Glazing

For traditional ceramics, glaze coatings often are applied to dried or bisque-fired ceramic ware

prior to firing. Glazes, which resemble glass in structure and texture, provide a smooth, shiny surface

that seals the ceramic body. Glazes consist primarily of oxides and can be classified as raw glazes or

frit glazes. In raw glazes, the oxides are in the form of minerals or compounds that melt readily and

act as solvents for the other ingredients. Some of the more commonly used raw materials for glazes

are quartz, feldspars, carbonates, borates, and zircon. A frit is a prereacted glass. Frit manufacturing

is addressed in AP-42 Section 11.14.

To prepare glazes, the raw materials are ground in a ball mill or attrition mill. Glazes

generally are applied by spraying or dipping. Depending on their constituents, glazes mature at

temperatures of 600° to 1500°C (1110° to 2730°F). Table 2-4 lists the compositions of several

commercial glazes.

2.2.9 Firing

Firing is the process by which ceramics are thermally consolidated into a dense, cohesive body

composed of fine, uniform grains. This process also is referred to as sintering or densification. The

characteristics of unfired ceramics that most affect firing are particle size, density, and particle shape.

In general: (1) ceramics with fine particle size fire quickly and require lower firing temperatures;

(2) dense unfired ceramics fire quickly and remain dense after firing with lower shrinkage; and

(3) irregular shaped ceramics fire quickly. Other material properties that affect firing include material

surface energy, diffusion coefficients, fluid viscosity, and bond strength.

Parameters that affect firing include firing temperature, time, pressure, and atmosphere.

Ceramics generally are fired at 50 to 75 percent of the absolute melting temperature of the material.

Table 2-5 lists typical firing temperatures for several ceramic products. Firing occurs faster at higher

temperatures, but so does coarsening. A short firing time results in a product that is porous and has a

low density; short to intermediate firing time results in fine-grained (i.e., having particles not larger

than 0.2 millimeters), high-strength products; and long firing times result in a coarse-grained products

that are more creep resistant. Applying pressure decreases firing time and makes it possible to fire

materials that are difficult to fire using conventional methods. Oxidizing or inert atmospheres are used

to fire oxide ceramics to avoid reducing transition metals and degrading the finish of the product.

2-12
TABLE 2-4. COMPOSITIONS OF COMMERCIAL GLAZESa

Oxide

Glaze for

hard paste

porcelain

Glaze for

soft paste

porcelain

Sanitary

ware glaze

Bristol

glaze

Wall tile

glaze

Semivitreous

dinnerware

glaze

Vitreous

dinnerware

glaze

Low

expansion

semicrystalline

glaze

Dinnerware

glaze

Cone 0

dinnerw

glaze

SiO2 78.00 73.83 59.71 67.09 62.25 59.09 55.79 53.91 55.88 42.45 Al2O3 13.24 14.32 18.58 13.01 10.36 13.53 7.37 26.98 9.57 7.04 B2O3 1.36 4.30 5.47 4.98 6.04 8.93 ZrO2 0.57 0.72 Li2O 0.51 9.08Na2O 2.05 1.98 6.54 1.81 1.81 3.06 2.46 K2O 3.67 4.96 3.12 3.01 1.47 3.92 2.71 5.05 1.72 MgO 2.57 0.16 0.96 0.62 CaO 5.10 6.89 11.15 7.16 7.67 11.76 9.16 7.65 3.09 ZnO 5.39 5.19 10.18 10.94 SrO 4.12 3.07BaO 2.50 PbO 16.08 35.30 

aReference 10. Numbers represent percent of the specified compound used in the manufacture of the specified glaze.

2-13
TABLE 2-5. TYPICAL FIRING TEMPERATURES OF CERAMICSa

Product Firing temperature

°C °F

Pottery

Ceramic cooking pots 1120-1180 2050-2150

Flower pots 860-1010 1580-1850

Stoneware (chemical) 1450-1480 2650-2700

Stoneware (once fired) 1270-1330 2318-2426

Earthware or semi-vitreous ware-bisque 1250-1290 2282-2354

Earthware or semi-vitreous ware-glost 1190-1250 2174-2282

Artware-bisque 1010-1200 1850-2200

Artware-glost 980-1320 1800-2400

Pottery decalcomanias 700-820 1300-1500

Whitewares:

Electrical porcelain 1150-1260 2100-2300

Hotel china-bisque 1200-1260 2200-2300

Sanitaryware-bisque 1200-1320 2200-2400

Hotel china-glost 1040-1230 1900-2250

Sanitaryware-glost 1230-1270 2246-2318

Floor tile 1150-1230 2100-2250

Wall tile-bisque 980-1200 1800-2200

Wall tile-glost 980-1230 1800-2250

Porcelain enamels:

Wet process cast iron enamels 620-760 1150-1400

Dry process cast iron enamels 840-930 1550-1700

Sheet iron ground coat enamels 760-870 1400-1600

Sheet iron cover coat enamels 750-840 1380-1550

A-19 coating 860-880 1580-1620

Solaramic 930-1090 1700-2000

Aluminum 480-590 900-1100

Electronic and newer ceramics:

Steatites 1260-1350 2300-2460

Aluminas 1540-1760 2800-3200

Titanates 1290-1370 2350-2500

Ferrites 1200-1450 2190-2650

Beryllia Up to 1870 Up to 3400

Rare earths 1370-2200 2500-4000

Cermets 1590-1700 2900-3100

a

Reference 7.

2-14
In addition to conventional firing, other methods used include pressure firing, hot forging,

plasma firing, microwave firing, and infrared firing. The following paragraphs describe conventional

and pressure firing, which are the methods used most often.

Conventional firing is accomplished by heating the green ceramic to approximately two-thirds

of the melting point of the material at ambient pressure and holding it for a specified time in a kiln.

Kilns can be classified as periodic (intermittent) or tunnel (continuous). Periodic kilns are heated and

cooled according to prescribed schedules. The heat for periodic kilns generally is provided by

electrical element or by firing with gas or oil. Periodic kilns can be classified as shuttle kilns, in

which the kiln is fixed and the ceramics loaded on rails are run into the kiln for firing, and elevator

kilns, in which the kiln is lowered onto the kiln car or the kiln car is lowered into the kiln for firing.

Tunnel kilns are long refractory chambers with constant temperature zones through which kiln

cars are passed to provide the specified time-temperature cycle. Tunnel kilns generally have separate

zones for cooling, firing, and preheating or drying. The kilns may be designed so that (1) the air

heated in the cooling zone moves into the firing zone and the combustion gases in the firing zone are

conveyed to the preheat/drying zone then exhausted, or (2) the air heated in the cooling zone is

conveyed to the preheat/drying zone and the firing zone gases are exhausted separately. The most

commonly used tunnel kiln design is the roller hearth (roller) kiln. In conventional firing, tunnel kilns

generally are fired with gas, oil, coal, or wood.

Advanced ceramics often are fired in electric resistance-heated furnaces with controlled

atmospheres. For some products, separate furnaces may be needed to eliminate organic lubricants and

binders prior to firing.

Ceramic products also are manufactured by pressure firing, which is similar to the forming

process of dry pressing except that the pressing is conducted at the firing temperature. The application

of pressure enhances the densification of the ceramic during firing. Because of its higher costs,

pressure firing is usually reserved for manufacturing ceramics that are difficult to fire to high density

by conventional firing. In hot pressing, hydraulic presses and graphite dies commonly are used. In

hot isostatic pressing, the pressing medium typically is a gas, such as argon or nitrogen.

2.2.10 Final Processing

Following firing, some ceramic products are processed further to enhance their characteristics

or to meet dimensional tolerances. Ceramics can be machined by abrasive grinding, chemical

polishing, electrical discharge machining, or laser machining. Annealing at high temperature, followed

by gradual cooling can relieve internal stresses within the ceramic and surface stresses due to

machining. Ceramics that are oxygen sensitive often are annealed in a controlled atmosphere to

achieve the stoichiometry that optimizes properties. Oxidation can increase the strength of certain hotpressed ceramics. Flame polishing is sometimes used to reduce surface flaws. In addition, surface

coatings are applied to many fired ceramics. Surface coatings are applied to traditional clay ceramics

to create a stronger, impermeable surface and for decoration. Coatings also may be applied to improve

strength and resistance to abrasion and corrosion. Coatings can be applied dry, as slurries, by

spraying, or by vapor deposition.

2-15
2.3 EMISSIONS1,3-5,12-13

The primary pollutants associated with raw material beneficiation are particulate matter (PM)

and PM less than 10μm in aerodynamic diameter (PM-10). Particulate matter is emitted from raw

material crushing, grinding, screening, classifying, handling, transfer, and storage. In addition, raw

material calciners emit filterable and condensible PM, which may include metals and other inorganic

pollutants. In addition, calciners emit products of combustion such as nitrogen oxides (NOx), sulfur

oxides (SOx), carbon monoxide (CO), carbon dioxide (CO2), and volatile organic compounds (VOC).

Emissions of SOx are a function of the sulfur content of the fuel used to fire the calciners and the

sulfur content of the raw materials used to manufacture ceramics. Emissions of VOC result from

incomplete combustion and volatilization of the organic material in the raw material. Other

beneficiation processes that are associated with emissions include acid leaching and granulation.

Emissions of hydrochloric acid (HCl) or other acids may arise from leaching. In addition, products of

combustion are emitted from spray dryers used for granulation.

Mixing generally is a wet process. However, VOC emissions from this step may arise from

the volatilization of binders, plasticizers, and lubricants. Forming generally is performed in sealed

containers and often is a wet process; emissions from this step in the process are likely to be

negligible. For ceramic bodies that are dry-formed, PM is likely to be emitted from grinding,

punching, and other green machining activities.

Particulate matter emissions consisting of metal and mineral oxides also arise from glaze

preparation, which includes mixing and grinding. Emissions of PM from glaze application also are

likely, if the glaze is applied by spraying.

Emissions associated from green ceramic heat treating processes, which include drying,

presinter thermal processing, and firing, include combustion products and filterable and condensible

PM. Particulate matter emissions consist, in part, of metals and the inorganic minerals associated with

the raw materials. Emissions of the products of combustion are a function of fuel type, raw material

constituents, process temperature, and other operating parameters.

Emissions of fluorine compounds also are associated with firing. Fluorine is present in

ceramic raw materials in the range of 0.01 to 0.2 percent. As the temperature of the green ceramic

bodies reaches 500° to 600°C (930° to 1110°F), the fluorine in the raw material forms hydrogen

fluoride (HF) and other fluorine compounds such as silicon tetrafluoride. Much of the fluorine is

released as HF. However, if lime is present in the ceramic body, HF reacts with the lime to form

calcium fluoride (CaF2), thereby reducing potential HF emissions. Other factors that reduce fluorine

emissions from ceramic kilns are listed in Table 2-6.

Other emission sources associated with ceramics manufacturing include final processing

operations and fugitive dust sources. The final processing steps include grinding and polishing, which

can emit PM and PM-10, and surface coating, annealing, and chemical treatment, which can emit

VOC. Fugitive dust sources, which consist of vehicular traffic, wind erosion of storage piles, and

materials handling and transfer, emit PM and PM-10.

2.4 EMISSION CONTROL TECHNOLOGY12-19

Several techniques have been used to control PM emissions from the mechanical processing of

ceramic raw materials and finished products. Fabric filters are the commonly used control device, but

wet scrubbers and electrostatic precipitators (ESP’s) also have been used. Fabric filters, wet scrubbers,

2-16
and ESP’s also are used to control emissions from clay calciners and dryers. Venturi scrubbers and

TABLE 2-6. FACTORS THAT REDUCE HF EMISSIONSa

Factor Process control technology

Body chemistry Use of high lime raw materials or lime additions

Body and setting density Employ higher density of body or setting pattern

Atmospheric water Use of low hydrogen content fuels

Preheating rate Increase above dehydroxylation temperature

Soak temperature Reduce to a minimum

Vitrification Increase through use of sintering aids

Soak duration Reduce to a minimum

Kiln draft Reduce to a minimum

Kiln exhaust temperature Reduce to a minimum

a

Reference 13.

fabric filters are used to control emissions from granulation (spray dryers) and from glaze preparation

and application. Afterburners have been used to control VOC emissions from tape casting operations.

Emissions from kilns generally are uncontrolled.

Table 2-6 lists process modifications that can be used to reduce HF emissions from kilns in the

ceramic manufacturing industry. Dry sorption scrubbing also has been used in the brick and ceramic

industries in Germany and in the brick industry in the U.S. to control emissions of HF. These devices

use limestone as a sorption medium to produce CaF2, which is removed by means of a rotating screen,

drum, or fabric filter. Control efficiencies of 95 to 99 percent have been reported for this type of

scrubber.

REFERENCES FOR SECTION 2

1. Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Volume 5, John Wiley &

Sons, New York, 1992.

2. 1987 Census of Manufactures, U. S. Department of Commerce, Washington, D.C., May 1990.

3. Ullman’s Encyclopedia of Industrial Chemistry, Fifth Edition, Volume A6.

4. D. W. Richerson, Modern Ceramic Engineering: Properties Processing, and Use in Design,

Marcel Dekker, Inc., New York, NY, 1982.

5. P. Vincenzini (ed.), Fundamentals of Ceramic Engineering, Elsevier Science Publishers, Ltd.,

New York, 1991.

6. G. Smith, "Operating the Spray Dryer", Ceramic Industry, 140 (6): 54-56, Business News

Publishing Company, Troy, MI, June 1993.

2-17
7. A. Hall, "Drying Technology for Today’s Manufacturer", Ceramic Industry, 142 (5): 30-33,

Business News Publishing Company, Troy, MI, May 1994.

8. H. J. Dowdle, "Grinding Glazes: A Comparison of Milling Methods", Ceramic Industry, 141 (4):

67-69, Business News Publishing Company, Troy, MI, May 1994.

9. A. H. Burgess, "Processing Trends in Tile Manufacturing", Ceramic Industry, 142 (3): 47-50,

Business News Publishing Company, Troy, MI, March 1994.

10. Ceramic Source 1990-1991, Volume 6, The American Ceramic Society, Westerville, OH, 1990.

11. Ceramic Industry 1994-95 Data Book & Buyers Guide Issue, Business News Publishing

Company, Troy, MI, July 15, 1994.

12. C. Palmonari and G. Timellini, Pollutant Emission Factors for the Ceramic Floor and Wall Tile

Industry, Journal of the Air Pollution Control Association, Volume 32, No. 10, Pittsburgh, PA,

October 1982.

13. D. Brosnan, "Technology and Regulatory Consequences of Fluorine Emissions in Ceramic

Manufacturing", American Ceramic Industry Bulletin, 71 (12), pp 1798-1802, The American

Ceramic Society, Westerville, OH, December 1992.

14. Particulate Emissions Test for American Olean Tile Company, Fayette, AL, Crushing and

Screening Line #1, October 15, 1991, Pensacola POC, Inc, Pensacola, FL, October 1991.

15. Particulate Emissions Test for American Olean Tile Company, Fayette, AL, Crushing and

Screening Line #2, October 16, 1991, Pensacola POC, Inc, Pensacola, FL, October 1991.

16. VOC Emission Test Report for GE Ceramics Tape Casters Fume Oxidizer, Chattanooga, TN,

September 13-15, 1989, IT-Air Quality Services Group, Knoxville, TN, October, 1989.

17. Exhaust Emission Sampling for Norton Company, Soddy-Daisy, TN, April 19-20, 1994, Armstrong

Environmental, Inc., Dallas, TX, April 1994.

18. Particulate Emission Evaluation for Steward, Inc., Chattanooga, TN, March 30, 1993, FBT

Engineering and Environmental Services, Chattanooga, TN, May 1993.

19. Calciners and Dryers in the Mineral Industries--Background Information for Proposed Standards,

EPA-450/3-85-025a, U. S. Environmental Protection Agency, Research Triangle Park, NC

October 1985.

2-18
3. GENERAL DATA REVIEW AND ANALYSIS PROCEDURES

3.1 LITERATURE SEARCH AND SCREENING

Data for this investigation were obtained from a number of sources within the Office of Air

Quality Planning and Standards (OAQPS) and from outside organizations. The AP-42 background

files located in the Emission Factor and Inventory Group (EFIG) files were reviewed for information

on the industry, processes, and emissions. The Factor Information and Retrieval (FIRE),

Crosswalk/Air Toxic Emission Factor Data Base Management System (XATEF), and VOC/PM

Speciation Data Base Management System (SPECIATE) data bases were searched by SCC code for

identification of the potential pollutants emitted and emission factors for those pollutants. A general

search of the Air CHIEF CD-ROM also was conducted to supplement the information from these data

bases.

Information on the industry, including number of plants, plant location, and annual production

capacities, was obtained from the Census of Manufactures and other sources. The Aerometric

Information Retrieval System (AIRS) data base also was searched for data on the number of plants,

plant location, and estimated annual emissions of criteria pollutants. A number of sources of

information were investigated specifically for emission test reports and data. A search of the Test

Method Storage and Retrieval (TSAR) data base was conducted to identify test reports for sources

within the ceramic products manufacturing industry. Copies of these test reports were obtained from

the files of the Emissions, Monitoring, and Analysis Division (EMAD). The EPA library was

searched for additional test reports. Using information obtained on plant locations, State and Regional

offices were contacted about the availability of test reports. Publications lists from the Office of

Research and Development (ORD) and Control Technology Center (CTC) were also searched for

reports on emissions from the ceramic products manufacturing industry. In addition, representative

trade associations, including the Tile Council of America, the Ceramic Manufacturers’ Association,

and the American Ceramic Society, were contacted for assistance in obtaining information about the

industry and emissions.

To screen out unusable test reports, documents, and information from which emission factors

could not be developed, the following general criteria were used:

1. Emission data must be from a primary reference:

a. Source testing must be from a referenced study that does not reiterate information from

previous studies.

b. The document must constitute the original source of test data. For example, a technical

paper was not included if the original study was contained in the previous document. If the exact

source of the data could not be determined, the document was eliminated.

2. The referenced study should contain test results based on more than one test run. If results

from only one run are presented, the emission factors must be down rated.

3. The report must contain sufficient data to evaluate the testing procedures and source

operating conditions (e.g., one-page reports were generally rejected).

3-1
A final set of reference materials was compiled after a thorough review of the pertinent

reports, documents, and information according to these criteria.

3.2 DATA QUALITY RATING SYSTEM1

As part of the analysis of the emission data, the quantity and quality of the information

contained in the final set of reference documents were evaluated. The following data were excluded

from consideration:

1. Test series averages reported in units that cannot be converted to the selected reporting

units;

2. Test series representing incompatible test methods (i.e., comparison of EPA Method 5 front

half with EPA Method 5 front and back half);

3. Test series of controlled emissions for which the control device is not specified;

4. Test series in which the source process is not clearly identified and described; and

5. Test series in which it is not clear whether the emissions were measured before or after the

control device.

Test data sets that were not excluded were assigned a quality rating. The rating system used

was that specified by EFIG for preparing AP-42 sections. The data were rated as follows:

A—Multiple tests that were performed on the same source using sound methodology and

reported in enough detail for adequate validation. These tests do not necessarily conform to the

methodology specified in EPA reference test methods, although these methods were used as a guide

for the methodology actually used.

B—Tests that were performed by a generally sound methodology but lack enough detail for

adequate validation.

C—Tests that were based on an untested or new methodology or that lacked a significant

amount of background data.

D—Tests that were based on a generally unacceptable method but may provide an order-ofmagnitude value for the source.

The following criteria were used to evaluate source test reports for sound methodology and

adequate detail:

1. Source operation. The manner in which the source was operated is well documented in the

report. The source was operating within typical parameters during the test.

2. Sampling procedures. The sampling procedures conformed to a generally acceptable

methodology. If actual procedures deviated from accepted methods, the deviations are well

documented. When this occurred, an evaluation was made of the extent to which such alternative

procedures could influence the test results.

3-2
3. Sampling and process data. Adequate sampling and process data are documented in the

report, and any variations in the sampling and process operation are noted. If a large spread between

test results cannot be explained by information contained in the test report, the data are suspect and are

given a lower rating.

4. Analysis and calculations. The test reports contain original raw data sheets. The

nomenclature and equations used were compared to those (if any) specified by EPA to establish

equivalency. The depth of review of the calculations was dictated by the reviewer’s confidence in the

ability and conscientiousness of the tester, which in turn was based on factors such as consistency of

results and completeness of other areas of the test report.

3.3 EMISSION FACTOR QUALITY RATING SYSTEM1

The quality of the emission factors developed from analysis of the test data was rated using

the following general criteria:

A—Excellent: Developed only from A-rated test data taken from many randomly chosen

facilities in the industry population. The source category is specific enough so that variability within

the source category population may be minimized.

B—Above average: Developed only from A-rated test data from a reasonable number of

facilities. Although no specific bias is evident, it is not clear if the facilities tested represent a random

sample of the industries. The source category is specific enough so that variability within the source

category population may be minimized.

C—Average: Developed only from A- and B-rated test data from a reasonable number of

facilities. Although no specific bias is evident, it is not clear if the facilities tested represent a random

sample of the industry. In addition, the source category is specific enough so that variability within

the source category population may be minimized.

D—Below average: The emission factor was developed only from A- and B-rated test data

from a small number of facilities, and there is reason to suspect that these facilities do not represent a

random sample of the industry. There also may be evidence of variability within the source category

population. Limitations on the use of the emission factor are noted in the emission factor table.

E—Poor: The emission factor was developed from C- and D-rated test data, and there is

reason to suspect that the facilities tested do not represent a random sample of the industry. There

also may be evidence of variability within the source category population. Limitations on the use of

these factors are footnoted.

The use of these criteria is somewhat subjective and depends to an extent upon the individual

reviewer. Details of the rating of each candidate emission factor are provided in Section 4.

REFERENCE FOR SECTION 3

1. Technical Procedures for Developing AP-42 Emission Factors and Preparing AP-42 Sections,

EPA-454/B-93-050, Office of Air Quality Planning and Standards, U. S. Environmental Protection

Agency, Research Triangle Park, NC, October 1993.

3-3
4. AP-42 SECTION DEVELOPMENT

4.1 INTRODUCTION

This section describes how the revised AP-42 section on ceramic products manufacturing was

developed. First, descriptions of data sets reviewed for this revision are presented, followed by a

discussion of how candidate emission factors were developed from the data. Finally, the proposed

changes to the existing AP-42 section on ceramic clay manufacturing are summarized.

4.2 REVIEW OF SPECIFIC DATA SETS

A total of 33 references were obtained for use in developing emission factors for ceramic

products manufacturing. References 14, 29, and 30 through 33 were not used for emission factor

development. Reference 14 was not used because the process tested was a plastics manufacturing

process rather than a ceramics process. Reference 29 was not used because it does not contain a

process description or process data, and Reference 30 does not contain any original test data.

References 31 through 33 were not used because they do not contain sufficient process data for

emission factor development.

4.2.1 Reference 1

This reference consists of a technical journal article and includes a brief description of ceramic

floor and wall tile manufacturing, a discussion of emissions and controls, and a table of emission

factors for several emission sources associated with the industry.

Emission factors are presented for uncontrolled and controlled emissions of PM, fluorine, and

lead from raw material processing, glaze milling, and ceramic tile bisque-firing and firing. The article

does not identify the type of control device on which the controlled emission factors are based.

However, typical control devices are identified by source, and it is assumed that the controlled factors

represent emissions controlled with the typical control devices listed.

The article states that the emission factors are based on the results of "thousands of

measurements" over a 7-year period, but does not provide details on specific emission tests. The

factors are presented in units of grams emitted per square meter (g/m2

) of tile produced; the text

explains that 1 m2 of tile weighs 20 kilograms (kg). Using this conversion, the emission factors were

calculated in units of kg per megagram (kg/Mg) and pounds per ton (lb/ton). Table 4-1 summarizes

these emission factors from the article. Because this is a secondary reference with little

documentation, the data are not rated for use in developing emission factors.

4.2.2 Reference 2

This report documents measurements of uncontrolled filterable PM and fluoride emissions

from a small natural gas-fired roller kiln used to refire ceramics after application of decals, paint, or

ink screenings. This type of kiln maintains low operating temperatures and short product residence

times. The test was conducted in March 1989 to demonstrate compliance with State regulations.

Process rates were provided on the basis of production.

4-1
TABLE 4-1. SUMMARY OF EMISSION FACTORS FROM REFERENCE 1a

Source

Uncontrolled Controlledb

PM Fluorine Lead PM Fluorine 

kg/Mg lb/ton kg/Mg lb/ton kg/Mg lb/ton kg/Mg lb/ton kg/Mg lb/to

Raw material preparation andforming

2 4 0.16 0.32

Bisque firing— High porosity ware— Medium porosity ware— Colored low porosity ware— Light color low porosity ware

0.05 0.1

0.070.130.160.43

0.140.260.320.85

0.02 0.04

0.010.0150.020.035

0.00.00.00.0

Glaze milling and glazing 1 2 0.2 0.4 0.07 0.14 Glost firing— Slow— Fast

0.10.06

0.20.12

0.050.03

0.10.06

0.010.008

0.020.015

0.0350.015

0.070.03

0.010.005

0.00.0

Single firing--slow— Colored low porosity ware— Light color low porosity wareSingle firing--fast— Colored low porosity ware— Light color low porosity ware

0.10.06

0.20.12

0.160.430.050.13

0.320.850.10.25

0.0150.01

0.030.02

0.0250.02

0.050.04

0.020.0350.010.015

0.00.00.00.0

aAll emission factors in units of kg/Mg and lb/ton of tile produced. Data are not rated.bEmissions from glaze milling and glazing controlled with venturi scrubbers; emissions from other sources controlled with fabr

4-2
Filterable PM emissions were measured using Method 5, and fluoride emissions were

measured using Kentucky Bureau of Environmental Protection Method 130, which is equivalent to

EPA Method 13B. Three test runs were conducted. In addition, CO2 concentrations were measured

by Orsat and reported for the three test runs. Emission factors were developed for emissions of

filterable PM, fluoride, and CO2 from the kiln. The emission data are rated B. The test methodology

was sound, and no problems were reported. However, because the report included no details on the

process, and process rates were estimated rather than measured during the test, a higher rating is not

warranted.

4.2.3 Reference 3

This report documents measurements of uncontrolled filterable PM and fluoride emissions

from a natural gas-fired kiln used to manufacture ceramic tile. The test was conducted at the same

facility discussed in Reference 2, but was conducted on a different kiln. The test was performed in

April 1989 to demonstrate compliance with State regulations. Process rates were provided on the basis

of production.

Filterable PM emissions were measured using Method 5, and fluoride emissions were

measured using Kentucky Bureau of Environmental Protection Method 130. Three test runs were

conducted. Emission factors were developed for emissions of filterable PM and fluoride from the kiln.

The emission data are rated B. The test methodology was sound, and no problems were reported.

However, because the report included no details on the process, and process rates were estimated

rather than measured during the test, a higher rating is not warranted.

4.2.4 Reference 4

This report documents measurements of uncontrolled filterable PM, fluoride, and SO2

emissions from a gas-fired kiln used to manufacture ceramic bricks. The test was conducted in

September 1993 to demonstrate compliance with local regulations. Process rates were provided on the

basis of production.

The process consists of forming bricks from a clay blend, spraying a color pigment on the

outside surface, drying the bricks to a moisture content of 5 to 6 percent, then firing the bricks in a

tunnel kiln at a temperature of 1120°C (2050°F). A kiln cycle, the time for the bricks to exit the kiln

from the time they enter kiln, was 73 hours.

Filterable PM emissions were measured using Method 5, fluoride emissions were measured

using Method 13B, and Method 6 was used to measure SO2 emissions. Three test runs were

conducted. In addition, CO2 concentrations were measured by Orsat and reported for the three test

runs. Emission factors were developed for emissions of filterable PM, fluoride, SO2, and CO2 from

the kiln. The emission data are rated B. The test methodology was sound, and no problems were

reported. However, these data are not used for emission factor development in this section because

they are representative of structural clay product manufacturing, which is addressed in AP-42

Section 11.3.

4-3
4.2.5 Reference 5

This report documents measurements of uncontrolled filterable PM, fluoride, SO2, and NOx

emissions from a gas-fired tunnel kiln. The test was conducted in November 1993 to demonstrate

compliance with local regulations.

The facility operates three tunnel kilns and produces unglazed ceramic tile. During the test,

the kiln sampled was firing tile composed of a mixture of 40 percent clay and 60 percent shale. The

average sulfur content of the unfired tile was 0.064 percent. Process rates were based on the average

rate of fired tile produced.

Filterable PM emissions were measured using Method 5, fluoride emissions were measured

using Method 13A, SO2 emissions were measured using Method 6C, and NOx emissions were

quantified using Method 7E. Three test runs were conducted. In addition, CO2 concentrations were

measured by Orsat and reported for the three test runs. According to the observer from the local air

pollution control agency, the SO2 measurements were not valid due to equipment problems during the

test. However, the major problem appears to be the way in which the post-test calibration was

conducted. Also, the test firm had difficulty with the pretest calibration.

Emission factors were developed for emissions of filterable PM, fluoride, NOx, and CO2 from

the kiln. The emission data are rated B, except for the SO2 data, which are rated C because of the

calibration problems. The test methodology was sound, but the report lacked adequate details on the

process to warrant a higher rating.

4.2.6 Reference 6

This report documents measurements of uncontrolled filterable PM, fluoride, and SO2

emissions from three gas-fired tunnel kilns ducted to a common stack. The test was conducted in

March and April of 1994 to demonstrate compliance with local regulations.

The facility tested is the same plant for which an emission test was documented in

Reference 5. At the time of the test documented in Reference 5, the three kilns were ducted to

separate stacks. However, prior to the test documented in this reference, the exhausts for all three

kilns were ducted to the same stack. During the test, two of the kilns were firing tile formed from

100 percent clay, and the other kiln was firing tile composed of a mixture of 30 percent clay and

70 percent shale. The average raw material sulfur content during the month of the test was

0.11 percent. Process rates were based on the average rate of fired tile produced.

Filterable PM emissions were measured using Method 5, fluoride emissions were measured

using Method 13A, and SO2 emissions were measured using Method 6. Three test runs were

conducted. In addition, CO2 concentrations were measured by Orsat and reported for six test runs.

Emission factors were developed for emissions of filterable PM, fluoride, SO2, and CO2 from the kiln.

The emission data are rated B. The test methodology was sound, and no problems were reported.

However, the report lacked adequate details on the process to warrant a higher rating.

4-4
4.2.7 Reference 7

This report documents measurements of uncontrolled filterable PM, fluoride, SO2, and NOx

emissions from a gas-fired tunnel kiln. The test was conducted in August 1993 to demonstrate

compliance with local regulations.

The kiln tested was a fast fire roller hearth design tunnel kiln. The kiln includes a preheat

section that uses excess heat from the kiln, a firing section, and a cooling section. Emissions from the

preheating and firing sections are ducted to one stack, and the emissions from the cooling section of

the kiln are ducted to a separate stack. At the time of the test the facility was producing ceramic wall

tile. The materials used in the process included talc, clay, wollastonite, and pyrophyllite. The average

raw material sulfur content from May through June, 1993, was 0.0089 percent. Because the same type

of ceramic was produced during testing, this sulfur content is assumed to be similar to the average

sulfur content during testing. Process rates were based on the average rate of fired tile produced.

Filterable PM emissions were measured using Method 5, fluoride emissions were measured

using Method 13A, SO2 emissions were measured using Method 6, and NOx emissions were quantified

using Method 7E. Three test runs were conducted. In addition, CO2 concentrations were measured by

Orsat and reported for the three test runs.

Emission factors were developed for emissions of filterable PM, fluoride, SO2, NOx, and CO2

from the kiln. The emission data are rated B. The test methodology was sound, and no problems

were reported. However, the report lacked adequate details on the process to warrant a higher rating.

4.2.8 Reference 8

This report documents measurements of controlled filterable PM emissions from a first

crushing and screening line used in the manufacture of ceramic tile. The test was conducted in

October 1991 to demonstrate compliance with local regulations. Process rates were provided on the

basis of production.

The line tested processes raw material, and PM emissions generated from the process are

controlled with a fabric filter. The exhaust from the fabric filter then is discharged to the atmosphere

through a stack.

Filterable PM emissions were measured using Method 5. Three 60-minute test runs were

conducted. Emission factors were developed for emissions of filterable PM from the process. The

emission data are rated B. The test method was sound, and no problems were reported. However,

only average process rates were reported.

4.2.9 Reference 9

This report documents measurements of controlled filterable PM emissions from a crushing

and screening line used in the manufacture of ceramic tile. The facility was the same facility

discussed in Reference 8, but a different processing line was sampled during this test. The test was

conducted in October 1991 to demonstrate compliance with local regulations. Process rates were

provided on the basis of production.

4-5
The crushing and screening line processes both raw material and grog (calcined fire clay).

Emissions from the line are controlled with two fabric filters, one for body material and one for grog.

The exhaust from the fabric filters is then combined and discharged to the atmosphere through a single

stack. The test was conducted downstream from the point where the two exhaust streams combine.

Filterable PM emissions were measured using Method 5. Three 60-minute test runs were

conducted. Emission factors were developed for emissions of filterable PM from the process. The

emission data are rated B. The test method was sound, and no problems were reported. However,

only average process rates were reported.

4.2.10 Reference 10

This report documents measurements of controlled TOC emissions from ceramic tape casters.

The test was conducted in September 1989 to demonstrate compliance with local regulations.

The facility operates two tape casters, followed by a gas-fired fume oxidizer (incinerator) for

emission control. Solvents used in the process include toluene and methyl isobutyl ketone. The

vapors are captured by a series of hoods and associated duct work and conveyed to the incinerator.

Process rates were based on production.

Total organic compound (referred to as VOC in the summary data tables and in AP-42)

emissions were measured using Method 25A. Five test runs were conducted, but the first was void

due to an upset condition. Analysis of the samples collected during Run 2 indicated that the process

may not have reached steady state during the time of the test run. During Run 5, the process rate

dropped considerably and the results of the run are questionable. Therefore, only runs 2 and 3 were

used for emission factor development. An emission factor was developed for emissions of VOC (as

propane). Because only two valid test runs were conducted, the emission data are assigned a rating

of B.

4.2.11 Reference 11

This report documents measurements of uncontrolled filterable PM, HF, SO2, NOx, CO, TOC

(referred to as VOC in the summary data tables and in AP-42), and CO2 emissions from two gas-fired

kilns, one dryer, and one cooler. The test was conducted in April 1994 to demonstrate compliance

with local regulations.

The facility tested operates two kilns and produces ceramic saddles and spheres (used in

scrubbers) for the chemical industry. A clay/water mixture is extruded and cut, loaded into ceramic or

metal containers, and put onto pallets which are conveyed through a dryer operating at 127°C (260°F).

After drying, the pallets are slowly passed through four zones of the kiln as the operating temperature

increases from 704° to 1148°C (1300° to 2100°F). The total cure time varies from 24 to 37 hours.

The finished product is then cooled and packaged for shipping.

The kiln exhaust flows through the dryer and the moist, warm gas exits the dryer at the rear

through a stack. Emissions tests were performed on the main stacks for both kilns, the dryer exhaust

for Kiln No. 1, and the cooler exhaust for Kiln No. 2. Process rates were based on the feed rates to

the kilns.

4-6
Filterable PM emissions were measured using Method 5, HF emissions were measured using

Method 13A, to measure SO2 emissions Method 6C was used, NOx emissions were quantified using

Method 7E, CO emissions were measured using Method 10, and VOC (as propane) emissions were

measured by Method 25A. In addition, CO2 concentrations were measured by Orsat and reported.

Three test runs were conducted for each source tested.

Emission factors were developed for emissions of filterable PM, HF, NOx, SO2, CO, VOC (as

propane), and CO2 from the kilns. Emission factors were developed for emissions of filterable PM

from the dryer and cooler. The emission data are rated B. The test methods were sound, and no

problems were reported. However, only average process rates were reported.

4.2.12 Reference 12

This report documents measurements of controlled TOC emissions from a ceramic furnace.

The test was conducted in August 1993 to demonstrate compliance with local regulations.

The facility produces circuit board components that are made of multilayer ceramic sheets,

which are cut from prefired ceramic tape, plated, pressed, and cured. The source tested was an electric

furnace that is used to cure the ceramic circuit parts. Organic binders, solvents, and plasticizers are

used in the process.

A normal curing cycle lasts 24 hours and consists of four stages. Volatile organic compounds

and other evaporative substances volatilize during the first 5 hours (the binder burnout stage), as the

temperature in the furnace is gradually raised from 20° to 900°C (68° to (1652°F). During the

subsequent 7-hour period, the temperature in the furnace is gradually raised to 1350°C (2462°F), then

held constant for another 7-hour period. Finally, the product is cooled for 5 hours. All of the exhaust

gases vented through the stack are ignited with a natural gas flare.

The normal process weight is 12 lb/cycle. However, during the test a 36 lb charge was cured

in the furnace.

Total organic compound emissions were measured using Method 25A, and three test runs were

conducted. The runs spanned three of the 5 hours of the binder burnout stage, but it is unclear what

portion of total VOC for the cycle was emitted during the 3-hour sampling period. During the first

two runs, the TOC concentrations fluctuated between 2.6 and 3.6 ppm as carbon. However, a spike in

exhaust stream TOC concentrations (84 ppm as carbon) occurred near the end of the third run, and the

TOC concentrations were still elevated (25 ppm as carbon) when the run ended.

Emission factors were developed for emissions of TOC from the process by assuming that all

TOC were emitted over 5 hours at the average TOC emission rate for the three runs. Because the

emission measurements were made over only a relatively small span of the entire kiln cycle, and

because there is inadequate information for making an accurate estimate of total TOC emissions from

the furnace cycle, the emission data are rated D.

4.2.13 Reference 13

This report documents measurements of controlled filterable PM emissions from a spray dryer.

The test was conducted in March 1993 to demonstrate compliance with local regulations. Process

rates were provided on the basis of production.

4-7
The facility manufacturers electronic ceramics, toner carrier for copier machines, and cerium

carbonate. The source tested was the spray dryer on the electronic ceramics manufacturing line.

Ferrite powder, organic binder, and water are mixed, pelletized, and calcined. After cooling, the

material is wet-ground into a slurry, then dried in the spray dryer, which is heated by natural gas.

Hot, moist air exiting the spray dryer passes through a cyclone and fabric filter for ferrite powder

removal. The exhaust from the fabric filter is then discharged to the atmosphere.

Filterable PM emissions were measured using Method 5. Three test runs were conducted and

emission factors were developed for emissions of filterable PM from the process. The emission data

are rated A.

4.2.14 Reference 15

This reference is an inspection report made for the purpose of renewing the annual certificate

of operation for the facility from Reference 12. Although the report is not a primary reference for

emission data, it includes a process description and provides supplemental information on the facility.

4.2.15 Reference 16

This reference is an inspection report made for the purpose of renewing certificates of

operation for the facility from Reference 13. Although the report is not a primary reference for

emission data, it includes a process description and provides supplemental information on the facility.

4.2.16 Reference 17

This reference is an inspection report made for the purpose of renewing certificates of

operation for the facility from Reference 11. Although the report is not a primary reference for

emission data, it includes a process description and provides supplemental information on the facility.

4.2.17 Reference 18

This report documents measurements of filterable PM emissions from two spray booths used in

a ceramic glaze line. Emissions from the spray booths were controlled with a wet scrubber. The test

was conducted in August 1992, to demonstrate compliance with State regulations. Filterable PM

emissions were measured using Method 5, and three test runs were conducted. Correspondence

received from the Ohio EPA provided the process rate as the average tons of glaze used per hour.

The emission data are rated B. The test methodology was sound, and no problems were

reported. However, since the process rate was provided as a daily average, a higher rating is not

warranted.

4.2.18 Reference 19

This report documents measurements of filterable PM emissions from two spray booths used in

a ceramic spray line. Emissions from the spray booths were controlled with a wet scrubber. The test

was conducted in August 1992, to demonstrate compliance with State regulations. Filterable PM

emissions were measured using Method 5, and three test runs were conducted. Correspondence

received from the Ohio EPA provided the process rate as the average tons of glaze used per hour.

4-8
The emission data are rated B. The test methodology was sound, and no problems were

reported. However, since the process rate was provided as a daily average, a higher rating is not

warranted.

4.2.19 Reference 20

This report documents measurements of filterable PM emissions from two spray booths used in

a ceramic glaze line. Emissions from the spray booths were controlled with a wet scrubber. The test

was conducted in February 1994, to demonstrate compliance with State regulations. Filterable PM

emissions were measured using Method 5, and three test runs were conducted. The process rate was

provided as the average tons of glaze used per hour.

The emission data are rated B. The test methodology was sound, and no problems were

reported. However, since the process rate was provided as a daily average, a higher rating is not

warranted.

4.2.20 Reference 21

This report documents measurements of uncontrolled filterable PM and fluoride emissions

from a direct-, natural gas-fired roller kiln. The kiln was firing ceramic tile during the test program.

The test was conducted in May 1994, to demonstrate compliance with State regulations. Process rates

were provided on the basis of production.

Filterable PM and total fluoride emissions were measured using a combined EPA Method 5

and Method 13B sampling train. Three test runs were conducted and emission factors were developed

for emissions of filterable PM and total fluorides from the process. The emission data are rated A.

4.2.21 Reference 22

This reference (excerpts from a test report) documents measurements of uncontrolled filterable

PM and fluoride emissions from a direct-, natural gas-fired roller kiln (same kiln as that described in

Reference 21). The kiln was firing ceramic tile during the test program. The test was conducted in

June 1993, to demonstrate compliance with State regulations. An average process rate was provided

on the basis of production.

The test was conducted by the same firm that conducted the test described in Reference 21,

and the procedures and test methods are assumed to be identical. Three test runs were conducted and

emission factors were developed for emissions of filterable PM and fluorides from the process. The

emission data are rated C because only excerpts of the actual test report are available, and the process

rate is a daily average.

4.2.22 Reference 23

This reference (excerpts from a test report) documents measurements of uncontrolled filterable

PM and fluoride emissions from a direct-, natural gas-fired roller kiln (same kiln as that described in

Reference 21). The kiln was firing ceramic tile during the test program. The test was conducted in

February 1992, to demonstrate compliance with State regulations. An average process rate was

provided on the basis of production.

4-9
The test was conducted by the same firm that conducted the test described in Reference 21,

and the procedures and test methods are assumed to be identical. Three test runs were conducted and

emission factors were developed for emissions of filterable PM and fluorides from the process. The

emission data are rated C because only excerpts of the actual test report are available and the process

rate is a daily average.

4.2.23 Reference 24

This report documents measurements of venturi scrubber-controlled filterable PM emissions

from a natural gas-fired spray dryer. The dryer is part of a ceramic body preparation plant. The test

was conducted in October 1994, to demonstrate compliance with State regulations. An average

process rate was provided on the basis of production.

Filterable PM emissions were measured using EPA Method 5. Three test runs were conducted

and emission factors were developed for emissions of filterable PM from the process. The emission

data are rated B because scrubber operating parameters are not provided in the report.

4.2.24 Reference 25

This reference (excerpts from a test report) documents measurements of venturi scrubbercontrolled filterable PM emissions from a natural gas-fired spray dryer (same dryer as that described in

Reference 24). The test was conducted in April 1994, to demonstrate compliance with State

regulations. An average process rate was provided on the basis of production.

The test was conducted by the same firm that conducted the test described in Reference 24,

and the procedures and test methods are assumed to be identical. Three test runs were conducted and

emission factors were developed for emissions of filterable PM from the process. The emission data

are rated C because only excerpts of the actual test report are available, the process rate is a daily

average, and scrubber operating parameters are not provided.

4.2.25 Reference 26

This reference (excerpts from a test report) documents measurements of venturi scrubbercontrolled filterable PM emissions from a natural gas-fired spray dryer (same dryer as that described in

Reference 24). The test was conducted in January 1993, to demonstrate compliance with State

regulations. An average process rate was provided on the basis of production.

The test was conducted by the same firm that conducted the test described in Reference 24,

and the procedures and test methods are assumed to be identical. Three test runs were conducted and

emission factors were developed for emissions of filterable PM from the process. The emission data

are rated C because only excerpts of the actual test report are available, the process rate is a daily

average, and scrubber operating parameters are not provided.

4.2.26 Reference 27

This reference (excerpts from a test report) documents measurements of venturi scrubbercontrolled filterable PM emissions from a natural gas-fired spray dryer (same dryer as that described in

Reference 24). The test was conducted in February 1992, to demonstrate compliance with State

regulations. An average process rate was provided on the basis of production.

4-10
The test was conducted by the same firm that conducted the test described in Reference 24,

and the procedures and test methods are assumed to be identical. Three test runs were conducted and

emission factors were developed for emissions of filterable PM from the process. The emission data

are rated C because only excerpts of the actual test report are available, the process rate is a daily

average, and scrubber operating parameters are not provided.

4.2.27 Reference 28

This report documents measurements of uncontrolled filterable PM and lead emissions from a

ceramic spray booth. The spray booth used a lead-based glaze to coat ceramic tile during the test

program. The test was conducted in September 1989, to demonstrate compliance with State

regulations. An average process rate was provided on the basis of tons of glaze used per hour.

Filterable PM and lead emissions were measured using a combined EPA Method 5 and

Method 12 sampling train. Three test runs were conducted and emission factors were developed for

emissions of filterable PM and lead from the process. The emission data are rated A.

4.3 DEVELOPMENT OF CANDIDATE EMISSION FACTORS

Tables 4-2 and 4-3 summarize the test data from References 1 through 13 and 18 through 28,

and Tables 4-4 and 4-5 present the candidate emission factors for ceramic products manufacturing.

Emission factors were developed for firing--natural gas-fired kiln, refiring--natural gas-fired kiln,

comminution--raw material crushing and screening, forming--tape casting, dryers, coolers, granulation--

natural gas-fired spray dryers, and ceramic glaze spray booths. The emission factors were developed

by grouping data from similar combinations of source, pollutant, and control device, discarding the

inferior data sets, and averaging the emission factors derived from each data set.

Emission data for natural gas-fired kilns were available for a variety of ceramic products and

types of kilns. However, because most of the test reports include little information on raw material

composition and kiln operating parameters, there is little basis for grouping data sets according to how

these parameters affect emissions. Therefore, in most cases, data for different types of kilns and

products are grouped together to develop average emission factors. For CO, CO2, and NOx, this

approach appears reasonable because these emissions result primarily from fuel combustion. For

filterable PM, this approach appears reasonable because the data for different products and kilns

overlapped to a large extent. Fluoride and HF emissions are directly related to the raw material

fluorine content, but the test reports do not document the raw material fluorine content. Therefore, the

fluoride data are averaged together, and the HF data are averaged together.

One data set was separated by raw material type. The emission factors for SO2 are separated

by raw material sulfur content (documented in three of the four test reports), which is a primary source

of SO2 emissions from ceramic kilns. In addition, data for emissions from ceramic refiring kilns were

grouped separately because an industry representative indicated that these kilns are not similar to other

kilns used in the industry. The following paragraphs describe how the data presented in Tables 4-2

and -3 were used to develop the emission factors presented in Tables 4-4 and -5.

4.3.1 Filterable PM

An emission factor for uncontrolled filterable PM emissions from natural gas-fired kilns was

developed using A-rated data from one test, B-rated data from five tests, and C-rated data from three

4-11
TABLE 4-2. SUMMARY OF TEST DATA FOR CERAMIC KILNSa

Product Pollutant

No. of

runs

Data

rating

kg/Mg lb/ton 

Minimum Maximum Average Minimum Maximu

Ceramic tile Filterable PM 3 C 0.25 0.34 0.30 0.50 0.69 Ceramic tile Fluoride 3 B 0.70 0.99 0.86 1.4 2.0 Glazed structural clay tile Filterable PM 3 B 0.71 1.0 0.86 1.4 2.0 Glazed structural clay tile Fluoride 3 B 0.31 0.32 0.32 0.62 0.65 Glazed structural clay tile SO2 3 B 3.6 4.1 3.9 7.1 8.2 Glazed structural clay tile CO2 3 B 340 370 360 680 740 Unglazed ceramic tile Filterable PM 3 B 0.13 0.15 0.14 0.25 0.29 Unglazed ceramic tile Fluoride 3 B 0.31 0.34 0.32 0.62 0.69 Unglazed ceramic tile SO2 3 C 0.31 0.33 0.32 0.61 0.67 Unglazed ceramic tile NOx 3 B 0.42 0.52 0.47 0.83 1.0 Unglazed ceramic tile CO2 3 B 650 650 650 1,300 1,300 Unglazed ceramic tile Filterable PM 3 B 0.49 0.74 0.59 1.0 1.5 Unglazed ceramic tile Fluoride 3 B 0.14 0.17 0.16 0.28 0.33 Unglazed ceramic tile SO2 3 B 2.4 2.4 2.4 4.7 4.8 Unglazed ceramic tile CO2 6 B 70 160 140 130 320 Ceramic wall tileb Filterable PM 3 B 0.023 0.031 0.028 0.046 0.06Ceramic wall tileb Fluoride 3 B 0.019 0.048 0.036 0.037 0.09Ceramic wall tileb SO2 3 B 0.035 0.046 0.039 0.070 0.09Ceramic wall tileb NOx 3 B 0.14 0.15 0.14 0.29 0.30 Ceramic wall tileb CO2 3 B 100 110 100 190 220 Ceramic saddles/spheres Filterable PM 3 B 0.16 0.20 0.19 0.32 0.42 Ceramic saddles/spheres HF 3 B 0.17 0.22 0.20 0.34 0.44 Ceramic saddles/spheres SO2 3 B 0.49 0.54 0.51 0.98 1.1 

4-12
TABLE 4-2. (continued)

Product Pollutant

No. of

runs

Data

rating

kg/Mg lb/ton 

Minimum Maximum Average Minimum Maximum 

Ceramic saddles/spheres NOx 3 B 0.17 0.27 0.21 0.34 0.53 Ceramic saddles/spheres CO 3 B 1.6 4.0 2.4 3.3 8.0 Ceramic saddles/spheres VOC as propanec 3 B 0.15 0.23 0.19 0.31 0.45 Ceramic saddles/spheres CO2 1 C NA NA 600 NA NA Ceramic saddles/spheres Filterable PM 3 B 0.43 0.44 0.43 0.85 0.88 Ceramic saddles/spheres HF 3 B 0.23 0.28 0.26 0.45 0.56 Ceramic saddles/spheres SO2 3 B 2.7 3.6 3.3 5.4 7.2 Ceramic saddles/spheres NOx 3 B 0.24 0.25 0.24 0.48 0.50 Ceramic saddles/spheres CO 3 B 0.50 1.6 0.88 1.0 3.2 Ceramic saddles/spheres VOC as propanec 3 B 0.19 0.27 0.24 0.38 0.54 Ceramic saddles/spheres CO2 1 B 450 460 460 890 910 Electronic circuit boards VOC as propanec 3 D 6.4 51 22 13 100 Ceramic tileb Filterable PM 3 A 0.039 0.039 0.039 0.078 0.079 Ceramic tileb Fluoride 3 A 0.031 0.048 0.040 0.031 0.096 Ceramic tileb Filterable PM 3 C 0.019 0.058 0.040 0.038 0.12 Ceramic tileb Fluoride 3 C 0.0085 0.060 0.039 0.017 0.12 Ceramic tileb Filterable PM 3 C 0.024 0.041 0.032 0.048 0.081 Ceramic tileb Fluoride 3 C 0.023 0.095 0.054 0.045 0.19 

aFor firing green ceramics. Emission factors represent uncontrolled emissions unless noted; emission factors in units of kg/Mg and lb

produced.

bEmission factor represents emissions from a roller kiln.cVOC measured using EPA Method 25A. Emission factor may include nonphotochemically reactive compounds that are not consider

4-13
TABLE 4-3. SUMMARY OF TEST DATA FOR OTHER CERAMIC PRODUCTS MANUFACTURING 

Source Product APCDb Pollutant

No. of

runs

Data

rating

Emission factor, kg/Mg Emission fact

Minimum Maximum Average Minimum Maximu

Ceramic refiring kiln Ceramic tilec None Filterable

PM

3 B 0.031 0.039 0.034 0.062 0.0

Ceramic refiring kiln Ceramic tilec None Fluoride 3 B 0.0042 0.012 0.0094 0.0083 0.0Ceramic refiring kiln Ceramic tilec None CO2 2 B 47 50 49 94 Crushing/screening Ceramic wall tile FF Filterable

PM

3 B 0.037 0.044 0.041 0.074 0.0

Crushing/screening Ceramic wall tile FF Filterable

PM

3 B 0.071 0.087 0.081 0.14 0

Tape casting Ceramic tape AB VOC as

propaned

2 B 28 30 29 57 

Dryer Ceramic saddles/

spheres

None Filterable

PM

3 C 0.19 2.4 1.2 0.37 

Cooler Ceramic saddles/

spheres

None Filterable

PM

3 B 0.037 0.083 0.055 0.074 0

Spray dryer Electronic parts FF Filterable

PM

3 B 0.010 0.051 0.030 0.020 0

Ceramic glaze sprayboothse

ND WS Filterable

PM

3 B 0.55 1.7 1.1 1.1 

Ceramic glaze sprayboothse

Basins andurinals

WS Filterable

PM

3 B 0.32 0.94 0.66 0.63 

Ceramic glaze sprayboothse

Toilet tanks WS Filterable

PM

3 B 0.80 1.1 0.92 1.6 

Spray dryer Ceramic body

preparation

VS Filterable

PM

3 B 0.074 0.12 0.10 0.15 0

Spray dryer Ceramic body

preparation

VS Filterable

PM

3 C 0.054 0.079 0.063 0.11 0

4-14
TABLE 4-3. (continued)

Source Product APCDb Pollutant

No. of

runs

Data

rating

Emission factor, kg/Mg Emission facto

Minimum Maximum Average Minimum Maximu

Spray dryer Ceramic body

preparation

VS Filterable

PM

3 C 0.068 0.18 0.11 0.14 0

Spray dryer Ceramic body

preparation

VS Filterable

PM

3 C 0.063 0.16 0.11 0.13 0

Ceramic glaze spraybooth using leadbased glaze

Ceramic tile None Filterable

PM

3 A 9.3 10 9.7 19 

Ceramic glaze spraybooth using leadbased glaze

Ceramic tile None Lead 3 A 1.4 1.6 1.5 2.9 

aEmission factors in units of kg/Mg and lb/ton of material processed, unless noted.bFF = fabric filter, AB = afterburner, WS = wet scrubber, VS = venturi scrubber, ND = no data available.cKiln is used for refiring tile after decals, paint, or ink screening are applied. Kiln maintains a relatively low temperature and products are re

minutes.

dVOC measured using EPA Method 25A. Emission factor may include non-photochemically reactive compounds that are not considered VOeEmission factor units are kg/Mg and lb/ton of glaze used.

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TABLE 4-4. EMISSION FACTOR SUMMARY FOR NATURAL GAS-FIRED CERAMIC KILN

Product Pollutant

Number of

kilns tested

Emission

factor rating

Minimum,

kg/Mg (lb/ton)

Maximum,

kg/Mg (lb/ton)

Average em

factor, kg/Mg 

Ceramic saddles/spheres CO 2 D 0.88 (1.8) 2.4 (4.9) 1.6 (3.3Ceramic saddles/spheres,ceramic tile

CO2 5 D 100 (200) 650 (1300) 390 (780

Ceramic saddles/spheres,ceramic tile

Filterable PM 7 D 0.028 (0.055) 0.59 (1.2) 0.25 (0.4

Ceramic tile Fluoride 5 E 0.036 (0.072) 0.86 (1.7) 0.28 (0.5Ceramic saddles/spheres,ceramic tile

HF 2 E 0.020 (0.39) 0.32 (0.65) 0.23 (0.4

Ceramic saddles/spheres,ceramic tile

NOx 4

D 0.14 (0.29) 0.47 (0.95) 0.27 (0.5

Ceramic tile (0.1% sulfur rawmaterial)

SO2 1 E NA NA 2.1 (4.1

Ceramic tile (<0.07% sulfurraw material)

SO2 2 E 0.039 (0.078)b 0.32 (0.65)c 4.7 Sd (9.5 

Ceramic saddles/spheres VOC as

propaneb

2 D 0.19 (0.38) 0.24 (0.48) 0.22 (0.4

aEmission factors represent uncontrolled emissions; emission factor units are kg/Mg and lb/ton of fired ceramics produced.

NA = not applicable.

bFactor based on raw material with 0.0089 percent sulfur.cFactor based on raw material with 0.064 percent sulfur.d 0.078 0.65 Where S is the raw material sulfur content (percent). English units equation derived as follows: S (_______

+ _______)/2 0.0089 0.064 eVOC measured using EPA Method 25A. Emission factor may include nonphotochemically reactive compounds that are not c

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TABLE 4-5. EMISSION FACTOR SUMMARY FOR MISCELLANEOUS CERAMIC PRODUC

MANUFACTURING SOURCESa

Source Product APCDb Pollutant

No. of

tests

Emission

factor rating

Emission factor, kg/Mg (lb/ton

Minimum Maximum A

Ceramic refiring kiln Ceramic tilec None Filterable PM 1 E NA NA 0.0Ceramic refiring kiln Ceramic tilec None Fluoride 1 E NA NA 0.00Ceramic refiring kiln Ceramic tilec None CO2 1 E NA NA Crushing/screening Ceramic wall tile FF Filterable PM 2 D 0.041 (0.082) 0.081 (0.16) 0.0Tape casting Ceramic tape AB VOC as

propaned

1 E NA NA 

Dryer Ceramic saddles/

spheres

None Filterable PM 1 E NA NA 1

Cooler Ceramic saddles/

spheres

None Filterable PM 1 E NA NA 0.0

Spray dryer Electronic parts FF Filterable PM 1 E NA NA 0.0Spray dryer Misc. ceramics VS Filterable PM 4 D 0.063 (0.13) 0.11 (0.22) 0.0Ceramic glaze sprayboothe

Misc. ceramics WS Filterable PM 3 D 0.66 (1.3)e 1.1 (2.2)e 0.

Ceramic glaze sprayboothf

Ceramic tile None Filterable PM 1 E NA NA 9

Ceramic glaze sprayboothf

Ceramic tile None Lead 1 E NA NA 1

aEmission factor units are kg/Mg and lb/ton of material processed, unless noted. NA = not applicable.bFF = fabric filter, AB = afterburner, WS = wet scrubber, VS = venturi scrubber.cKiln is used for refiring tile after decals, paint, or ink screenings are applied. Emission factor units are kg/Mg and lb/ton of fired ceramics pdVOC measured using EPA Method 25A. Emission factor may include non-photochemically reactive compounds that are not considered VOeEmission factor units are kg/Mg and lb/ton of glaze used.fLead-based glaze used during testing. Emission factor units are kg/Mg and lb/ton of glaze used. Glaze contained 24.1 percent lead oxide.

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tests. The tests were conducted on seven kilns at six different facilities. The data from References 21

through 23 (same kiln) were averaged first and then were averaged with the other data. The data

range from 0.028 to 0.59 kg/Mg (0.055 to 1.2 lb/ton) and average 0.25 kg/Mg (0.49 lb/ton). This

candidate emission factor is assigned a D rating because it was developed using data that range over

an order of magnitude.

An emission factor for filterable PM emissions from a natural gas-fired ceramic refiring kiln

was developed using B-rated data from a single test. The emission factor is 0.034 kg/Mg

(0.067 lb/ton). This candidate emission factor is assigned an E rating because it was developed using

data from a single test.

An emission factor for filterable PM emissions from comminution (raw material crushing and

screening) was developed using B-rated data from two tests conducted on two crushing and screening

lines located at the same facility. Emissions from both lines were controlled by fabric filters. The

data range from 0.041 to 0.081 kg/Mg (0.082 to 0.16 lb/ton) and average 0.061 kg/Mg (0.12 lb/ton).

This candidate emission factor is assigned a D rating because it was developed using B-rated data

from two tests conducted at the same facility.

An emission factor for uncontrolled filterable PM emissions from a dryer (heated with the

exhaust from a natural gas-fired ceramic kiln firing ceramic saddles and spheres) was developed using

C-rated data from a single test. The emission factor is 1.2 kg/Mg (2.3 lb/ton). This candidate

emission factor is assigned an E rating because it was developed from C-rated data.

An emission factor for uncontrolled filterable PM emissions from a cooler (following a natural

gas-fired ceramic kiln firing ceramic saddles and spheres) was developed using B-rated data from a

single test. The emission factor is 0.055 kg/Mg (0.11 lb/ton). This candidate emission factor is

assigned an E rating because it is based on data from a single test.

An emission factor for filterable PM emissions from spray dryers was developed using B-rated

data from a single test. The spray dryer tested was controlled by a fabric filter. The emission factor

is 0.030 kg/Mg (0.060 lb/ton). This candidate emission factor is assigned an E rating because it is

based on data from a single test.

An emission factor for filterable PM emissions from spray dryers controlled with venturi

scrubbers was developed using B-rated data from one test and C-rated data from three tests conducted

on the same dryer. The data range from 0.063 kg/Mg (0.13 lb/ton) to 0.11 kg/Mg (0.22 lb/ton) and

average 0.096 kg/Mg (0.19 lb/ton). This candidate emission factor is assigned a D rating because it

was developed using data from a single dryer.

An emission factor for filterable PM emissions from ceramic glaze spray booths controlled

with wet scrubbers was developed using B-rated data from three tests conducted on three different

spray lines at the same facility. The emission factor units for these factors are kg/Mg (lb/ton) of glaze

used. The data range from 0.66 kg/Mg (1.3 lb/ton) to 1.1 kg/Mg (2.2 lb/ton) and average 0.89 kg/Mg

(1.8 lb/ton). This candidate emission factor is assigned a D rating because it was developed using data

from a single facility.

An emission factor for filterable PM emissions from uncontrolled ceramic glaze spray booths

was developed using A-rated data from a single test. The spray booth tested was using a lead-based

glaze (24.1 percent lead oxide) during testing. The emission factor is 9.7 kg/Mg (19 lb/ton) of glaze

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used. This candidate emission factor is assigned an E rating because it was developed using data from

a single test.

4.3.2 Volatile Organic Compounds

The VOC emission factors described below are based on EPA Method 25A measurements.

Therefore, these factors actually represent total organic compounds and may include nonphotochemically reactive compounds that are not considered VOC.

An emission factor for uncontrolled VOC (as propane) emissions from natural gas-fired kilns

was developed using B-rated data from tests conducted on two kilns. The data range from 0.19 to

0.24 kg/Mg (0.38 to 0.48 lb/ton) and average 0.22 kg/Mg (0.43 lb/ton). This candidate emission factor

is assigned a D rating because it was developed using data from two kilns located at the same facility.

An emission factor for uncontrolled VOC (as propane) emissions from electric ceramic

furnaces (firing electronic circuit boards) was developed using the D-rated data presented in

Reference 12. However, this emission factor is not rated and is not proposed as a candidate emission

factor for the following reasons. The process entailed the manufacture of a specialty product in very

small quantities (36 lb per kiln cycle): the kiln was operating at three times the normal process weight

rate; and because of the fluctuations in emissions for the process, the emissions sampled are not likely

representative of an entire kiln cycle.

An emission factor for VOC (as propane) emissions from ceramic tape casters was developed

using B-rated data from a single test. The tape casters tested were controlled by an afterburner. The

emission factor is 29 kg/Mg (58 lb/ton). This candidate emission factor is assigned a E rating because

it was developed using data from a single test.

4.3.3 Carbon Monoxide

An emission factor for uncontrolled CO emissions from natural gas-fired kilns was developed

using B-rated data from tests conducted on two kilns. The data range from 0.88 to 2.4 kg/Mg (1.8 to

4.9 lb/ton) and average 1.6 kg/Mg (3.3 lb/ton). This candidate emission factor is assigned a D rating

because it was developed using data from two kilns located at the same facility.

4.3.4 Carbon Dioxide

An emission factor for uncontrolled CO2 emissions from natural gas-fired kilns was developed

using B-rated data from three tests and B- and C-rated data from two tests conducted at the same

facility. The data range from 100 kg/Mg (200 lb/ton) to 650 kg/Mg (1,300 lb/ton) and average

300 kg/Mg (590 lb/ton). This candidate emission factor is assigned a D rating because it was

developed using data from kilns located at only three facilities.

An emission factor for CO2 emissions from natural gas-fired ceramic refiring kilns was

developed using B-rated data from a single test. The emission factor is 49 kg/Mg (97 lb/ton). This

candidate emission factor is assigned an E rating because it was developed using data from a single

test.

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4.3.5 Nitrogen Oxides

An emission factor for uncontrolled NOx emissions from natural gas-fired kilns was developed

using B-rated data from four tests, two of which were conducted on kilns located at the same facility.

The data range from 0.14 to 0.47 kg/Mg (0.29 to 0.95 lb/ton) and average 0.27 kg/Mg (0.54 lb/ton).

This candidate emission factor is assigned a D rating because it was developed using data from kilns

located at only two facilities.

4.3.6 Sulfur Dioxide

An emission factor for uncontrolled SO2 emissions from natural gas-fired kilns firing ceramics

with a raw material sulfur content of 0.11 percent was developed using B-rated data from a single test.

The emission factor is 2.4 kg/Mg (4.8 lb/ton). In AP-42, this factor is presented as 22 S kg/Mg

(44 S lb/ton), where S is the raw material sulfur content (percent). This factor is assumed to be

applicable to facilities using raw material with a sulfur content greater than 0.07 percent. This

candidate emission factor is assigned an E rating because it was developed using data from a single

test. Data from two B-rated tests (Reference 11) are not used because of several inconsistencies in the

documented raw material sulfur analysis.

An emission factor for uncontrolled SO2 emissions from natural gas-fired kilns firing ceramics

with a raw material sulfur content of less than or equal to 0.07 percent was developed using data from

one B-rated test and one C-rated test. The emission factor, presented as an equation, is 4.7 S kg/Mg

(9.5 S lb/ton), where S is the raw material sulfur content (percent). This factor is assumed to be

applicable to facilities using raw material with a sulfur content less than or equal to 0.07 percent. This

candidate emission factor is assigned an E rating because it was developed using B- and C-rated data

from two tests.

4.3.7 Hydrogen Fluoride

An emission factor for uncontrolled HF emissions from natural gas-fired kilns was developed

using B-rated data from two tests conducted on two kilns located at a single facility. The data range

from 0.20 to 0.32 kg/Mg (0.39 to 0.65 lb/ton) and average 0.23 kg/Mg (0.46 lb/ton). This candidate

emission factor is assigned an E rating because it was developed using data from a single facility, and

HF emissions vary widely by facility.

4.3.8 Fluoride

An emission factor for fluoride emissions from natural gas-fired kilns was developed using

A-rated data from one test, B-rated data from four tests, and C-rated data from two tests. The A- and

C-rated tests were conducted on the same kiln, and these data were averaged first and then were

averaged with the B-rated data. The data range from 0.036 kg/Mg (0.072 lb/ton) to 0.86 kg/Mg

(1.7 lb/ton) and average 0.28 kg/Mg (0.56 lb/ton). This candidate emission factor is assigned an E

rating because it was developed using data that range over an order of magnitude.

An emission factor for fluoride emissions from a natural gas-fired ceramic refiring kiln was

developed using B-rated data from a single test. The emission factor is 0.0094 kg/Mg (0.019 lb/ton).

This candidate emission factor is assigned an E rating because it was developed using data from a

single test.

4-20
4.3.9 Lead

An emission factor for lead emissions from uncontrolled ceramic glaze spray booths was

developed using A-rated data from a single test. The spray booth tested was using a lead-based glaze

(24.1 percent lead oxide) during testing. The emission factor is 1.5 kg/Mg (3.0 lb/ton) of glaze used.

This candidate emission factor is assigned an E rating because it was developed using data from a

single test.

4.4 SUMMARY OF CHANGES TO AP-42 SECTION

4.4.1 Section Narrative

The process description was revised to reflect current industry practices and was expanded to

present a more complete description of the ceramic products manufacturing industry. A process flow

diagram also was added to the section based on the revised process description. In addition, emissions

from ceramic product manufacturing operations and types of emission control systems currently in use

are discussed. The previous version of this AP-42 section addressed the beneficiation of ceramic raw

materials only. Because the revised section addresses the entire process of manufacturing ceramic

products, the title of the AP-42 section also was changed to "Ceramic Products Manufacturing."

4.4.2 Emission Factors

The emission factors in the current AP-42 section are not presented in the revised section

because the background file did not contain any of the old AP-42 references. However, the

publication dates (pre-1970) indicate that any data from these references are probably not useful for

emission factor development. The candidate emission factors discussed in Section 4.3 of this report

are presented in the revised AP-42 section. Based on current guidelines for rating emission factors,

the new emission factors are assigned lower ratings (mostly "D-rated") than the "A-rated" factors

previously presented in AP-42. However, the new factors are based on more reliable and

representative test data. The SO2, fluoride, and HF emission factors are footnoted as being primarily

dependent of the types of raw materials (and fuel for SO2) used at specific facilities.

REFERENCES FOR SECTION 4

1. C. Palmonari and G. Timellini, Pollutant Emission Factors for the Ceramic Floor and Wall Tile

Industry, Journal of the Air Pollution Control Association, Volume 32, No. 10, Pittsburgh, PA,

October 1982.

2. Particulate Emission Testing for Florida Tile Corporation, Lawrenceburg, Kentucky, March 7-8,

1989, Air Systems Testing, Inc., Marietta, GA, April 1989.

3. Particulate Emission Testing for Florida Tile Corporation, Lawrenceburg, Kentucky, April 19,

1989, Air Systems Testing, Inc., Marietta, GA, May 1989.

4. Source Emission Tests at Stark Ceramics, Inc., East Canton, Ohio, No. 3 Kiln Stack,

September 16, 1993, Custom Stack Analysis Company, Alliance, OH, October 1993.

4-21
5. Metropolitan Ceramics, Canton, Ohio, Tunnel Kiln #3 Exhaust Stack, Particulate, SO2, NOx,

Hydrofluoric Acid Emission Evaluation, Conducted - November 17-18, 1993, Envisage

Environmental Incorporated, Richfield, OH, December 16, 1993.

6. Metropolitan Ceramics, Inc., Canton, Ohio, TK1, TK2, TK3 Exhausts, Particulate, Sulfur

Dioxides, & Fluorides Emission Evaluation, Conducted - March 30 & April 14, 1994, Envisage

Environmental Incorporated, Richfield, OH, May 9, 1994.

7. Source Evaluation Results, U. S. Ceramic Tile Company, East Sparta, Ohio, August 11, 1993,

Envisage Environmental Incorporated, Richfield, OH, September 1, 1993.

8. Particulate Emissions Test for American Olean Tile Company, Fayette, AL, Crushing and

Screening Line #1, October 15, 1991, Pensacola POC, Inc, Pensacola, FL, October 1991.

9. Particulate Emissions Test for American Olean Tile Company, Fayette, AL, Crushing and

Screening Line #2, October 16, 1991, Pensacola POC, Inc, Pensacola, FL, October 1991.

10. VOC Emission Test Report for GE Ceramics Tape Casters Fume Oxidizer, Chattanooga, TN,

September 13-15, 1989, IT-Air Quality Services Group, Knoxville, TN, October, 1989.

11. Exhaust Emission Sampling for Norton Company, Soddy-Daisy, TN, April 19-20, 1994, Armstrong

Environmental, Inc., Dallas, TX, April 1994.

12. Volatile Organic Compound Emission Testing, Golden Astro Furnace Exhaust, Coors Electronic

Package Company, Chattanooga, TN, August 26, 1993, Analytical Testing Consultants, Inc.,

Kannapolis, NC and Roswell, GA, September 1993.

13. Particulate Emission Evaluation for Steward, Inc., Chattanooga, TN, March 30, 1993, FBT

Engineering and Environmental Services, Chattanooga, TN, May 1993.

14. Emission Test Report, Walking Vane Bakeout Oven, 3M Corporation, Chattanooga, TN, Pedco

Environmental, Inc., Cincinnati, OH, May 1981.

15. Inspection Report, Coors Electronic Package Company, Chattanooga, TN, April 4, 1994,

Chattanooga-Hamilton County Air Pollution Control Bureau, Chattanooga, TN, May 1994.

16. Inspection Report, Steward, Inc., Chattanooga, TN, May 19, 1994, Chattanooga-Hamilton County

Air Pollution Control Bureau, Chattanooga, TN, August, 1994.

17. Inspection Report, Norton Company, Soddy-Daisy, TN, August 18, 1994, Chattanooga-Hamilton

County Air Pollution Control Bureau, Chattanooga, TN, August, 1994.

18. Report to American Standard on Stack Particulate Samples Collected at Tiffin, OH (Test Date

August 18, 1992), Affiliated Environmental Services, Inc., Sandusky, OH, August 24, 1992.

19. Report to American Standard on Stack Particulate Samples Collected at Tiffin, OH (Test Date

August 19, 1992), Affiliated Environmental Services, Inc., Sandusky, OH, August 24, 1992.

4-22
20. Report to American Standard on Stack Particulate Samples Collected at Tiffin, OH (Test Date

February 8, 1994), Affiliated Environmental Services, Inc., Sandusky, OH, February 15, 1994.

21. Emission Test Report--Plant A, Roller Kiln, May 1994, Document No. 4602-01-02, Confidential

Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S. Environmental

Protection Agency, Research Triangle Park, NC, June 8, 1995.

22. Emission Test Report (Excerpts)--Plant A, Roller Kiln, June 1993, Document No. 4602-01-02,

Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.

Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

23. Emission Test Report (Excerpts)--Plant A, Roller Kiln, February 1992, Document

No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159, Assignment

No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

24. Emission Test Report--Plant A, Spray Dryer, October 1994, Document No. 4602-01-02,

Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.

Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

25. Emission Test Report (Excerpts)--Plant A, Spray Dryer, April 1994, Document No. 4602-01-02,

Confidential Business Information Files, Contract No 68-D2-0159, Assignment No. 2-01, U. S.

Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

26. Emission Test Report (Excerpts)--Plant A, Spray Dryer, January 1993, Document

No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159, Assignment

No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

27. Emission Test Report (Excerpts)--Plant A, Spray Dryer, February 1992, Document

No. 4602-01-02, Confidential Business Information Files, Contract No 68-D2-0159, Assignment

No. 2-01, U. S. Environmental Protection Agency, Research Triangle Park, NC, June 8, 1995.

28. Stationary Source Sampling Report Reference No. 6445, Lead and Particulate Emissions Testing,

Spray Booth 2A Stack, Entropy Environmentalists, Inc., Research Triangle Park, NC,

September 20, 1989.

29. Stack Emission Evaluation of Beryllium Oxide in a Specialty Ceramic Product Development and

Formation Operation, Accredited Laboratories, Inc., Carteret, NJ, May 1988.

30. Evaluation of Estimated Particulate Emissions from Proposed Tunnel Kilns, Steward, Inc.,

Chattanooga, TN, Chattanooga-Hamilton County Air Pollution Control Bureau, Chattanooga, TN,

October 1994.

31. Test Report for the Determination of Organic Compound Destruction Efficiency from SRK Kilns

and Tokai Bakeout Ovens, Prepared for: Murata Erie North America, State College, PA, Scott

Environmental Technology, Plumsteadville, PA, August 1992.

32. Ceramic Kiln Afterburner Testing, Murata Erie North America, State College, PA, Hemeon

Associates, Inc., Pittsburgh, PA, October 23, 1991.

4-23
33. Hydrogen Cyanide Emission Testing, Foseco, Inc., Mt. Braddock Plant, Mt. Braddock, PA,

Hemeon Associates, Inc., Pittsburgh, PA, April 16, 1990.

4-24
5. PROPOSED AP-42 SECTION 11.7

The proposed AP-42 Section 11.7, Ceramic Products Manufacturing, is presented on the

following pages as it would appear in the document.

5-1