Date: October 1, 2008 (Finalized: January 13, 2009)

Subject: Site Visit – Interceramic, Garland, Texas Clay Ceramics Manufacturing NESHAP EPA Contract No. EP-D-06-118; EPA Work Assignment No. 2-09 RTI Project No. 0210426.002.009

From: Richard Marinshaw

To: Jeff Telander EPA/SPPD/MMG (D243-02) U. S. Environmental Protection Agency Research Triangle Park, N.C. 27711

I. Purpose

The purpose of this visit was to observe the ceramic tile manufacturing process at the Interceramic Inc. (Interc eramic) facility and to collect info rmation on sources of hazardous air pollutant (HAP) emissions and emission controls in support of the redevelopment of national emission standards for hazardous air pollutants (N ESHAP) for the clay ceramics manufacturing industry.

II. Place and Date

Interceramic Inc. (Interceramic) 2333 South Jupiter Road Garland, Texas 75041

September 11, 2008

III. Attendees

Interceramic

Jorge Duran, Plant Manager Telephone: (214) 503-4941

Felipe Matan Merino, Technical Director Telephone: (214) 503-55002

U. S. Environmental Protection Agency

Jeff Telander Telephone: (919) 541-5427

RTI International

Richard Marinshaw Telephone: (919) 316-3735

IV. Discussion

A. Background

The Interceramic facility in Garland, Texa s manufactures ceramic wall tile and trim. The plant has an annual production capacity of 31.5 million square feet of tile. The primary raw materials used to make clay bodies at the plan t include ball clay, plastic -type clay, sand, calcium carbonate, and nepheline syenite. Glaze materials used at the plant include frits, metal-based stains, zirconium silicate, calcined alumina, kaolin, quartz, and hematite.

The Garland facility has a total of five roller kilns. However, due to market conditions, only two of the kilns are currently in operation: one “fie ld” tile kiln and one kiln for firing trim tile. The plant operates 24 hours per day, 7 days per week. The kilns are operated around the clock; the ball mills and spray dryer typically are operated onl y 3 days per week. When operating at capacity, the plant employs about 230 persons, but cu rrently there are only about 150 employees.

B. Process

The processing steps used at Interceramic include raw material storage, body material and glaze preparation, tile pressing, drying, gl azing, firing, inspection, and packaging. The following paragraphs describe the process in more detail.

1. Raw Material Storage

Raw materials used by Interceramic are received by trucks. The materials are emptied into hoppers and conveyed to silos for storage.

2. Preparation

From the storage silos, the raw materi als are deposited onto a weigh scale and conveyed to the grinding area. There, the mate rials are mixed with wa ter and ground in one of three ball mills, forming a slip. A typical grinding cycle lasts about 5 hours. From the ball mills, the slip is pumped to one of two blungers for fu rther mixing until it is ready for the spray dryer. From the blungers, the slip passes through vibrating screens to rem ove oversize material and is pumped to the spray dryer. The purpose of spray drying is to produce a powder of uniform3

particle size that can be poured and spread uniformly across tile di es for pressing. Otherwise, it is difficult to meet the size and quality specifications for larger ceramic tiles.

In the spray dryer, the slip is sprayed into a drying chamber, where hot air flows countercurrent to the slip spray a nd dries the slip, forming a fine powder. The powder falls to the bottom of the dryer and onto a conveyor. The spray dryer is fired with na tural gas. The dried material discharged from the spray dryer is convey ed to storage silos. As noted previously, the spray dryer currently is opera ted about 3 days per week.

During glaze preparation, the frits, calciu m carbonate, and kaolin are combined with water and ground in a ball mill to create the glaze mix. The glaze mix is then stored in large plastic and metallic containers until ready for use.

3. Pressing and Drying

In the pressing area, the spray-dried pow der is conveyed from the storage silos to hoppers that feed the hydraulic presses, which fo rm the unfired “green” tiles. A conveyor belt transfers the green tiles from the presses to a cont inuous tile dryer. Any defective green tiles are crushed and recycled back to the process. The original tile dryers, which are fired with natural gas, operate at a temperature of about 400°F. In May 2008, Interceramic installed a radiative heating dryer, which operates at about 350°F and uses only about 22 percent of the energy required by the older tile dryers. Waste heat from the new dryer can be used to preheat the

combustion air for the kiln. In addition, with the new dryer, th e total firing cycle has been

reduced from about 3 hours to 45 minutes.

4. Glazing

From the dryer, the dried tiles are ali gned and brushed before being sprayed with water for glaze application. Gl aze is applied to the tiles by th e curtain coating (waterfall) method, which provides a uniform coating over the f ace of the tile. After glazing, the tiles may be directed to a roller printer that applies patterns or designs to the tile f aces. The glazed tiles are then conveyed to a loading machin e, which places the tile s on racks for transporting to the kiln. Excess glaze from the curtain coaters is recycled back to the process.

5. Firing

The glazed tiles are transpor ted to and loaded into a roller kiln. As noted above, although Interceramic has five kilns, only two ar e currently in operation. All of the kilns are fired with natural gas. Afte r firing, the tiles are loaded ont o racks and transferred to the inspection and packagin g area of the plant.

6. Inspection and Packaging

The fired tiles are inspected for quality c ontrol. The inspecti on of field tiles is automated. However, trim tiles must be inspected manually. Defective tiles are recycled back to the process, while the good quality tiles are stacked and packaged for shipping using an automated process.4

C. Emissions and Controls

Emissions from the kilns include hydr ogen fluoride (HF), hydrogen chloride (HCl), sulfur dioxide (SO 2 ), particulate matter (PM), and products of combustion. The PM may include HAP metals from the glazes. The kilns at Inte rceramic are not equipped with emission controls because it is not a necessary requirement per the emission testing results that indicate all is within environmental state regulations.

Emissions from dusty operations, such as raw material handling and transfer, are controlled with fabric filters. Because the plan t uses curtain coating, th ere are no emissions from the glazing process. Emissions from the spra y dryer are controlled with a wet scrubber. Interceramic recycles the wastew ater generated by the scrubber.