Permit Summary – Addition of a Kiln and Related Operations 

At CEMEX Facility in Clinchfield, GA 

Project Description

This modification involves the construction of a new dry process Portland cement 

manufacturing line (Kiln No. 6) capable of producing 1,405,104 short tons per year of 

cement clinker. The modification includes raw material handling and storage, kiln feed 

preparation with an in-line raw mill, a dry process rotary kiln coupled with preheater and 

calciner, a clinker cooler, a coal/pet coke mill, a finish mill, and cement storage, 

packaging and shipping operations. 

Fuels authorized for Kiln No. 6 include natural gas, coal, petroleum coke, fuel oils, 

landfill gas, and other non-hazardous liquid and solid fuels such as “on-specification” 

used oil fuels, plastic, filter fluff and wood wastes. 

Kiln No. 6 uses Selective Non-Catalytic Reduction (SNCR) in combination with staged 

and controlled combustion (SCC) and low NOx burners to minimize NOx emissions from 

the pyroprocessing processes. Fabric filters/baghouses are employed to capture PM 

emitted from various process units. A hydrated lime injection system is used as 

necessary to comply with SO2 emission limits for the kiln. Kiln No. 6 is also designed 

and will be operated in a mode to minimize emissions of CO and VOC via controlled 

combustion, and SO2 via raw material management and hydrated lime injection. 

Relevant PSD/BACT Permit Conditions

A. Overall Emission limits (any 12 consecutive months) 

 SO2 – 703 toms 

 NOx – 1,370 tons 

 CO – 2,037 tons 

 VOC – 351 tons 

 PM – 234 tons, including no more than 199 tons PM10

B. Overall Production Limit 

 160.4 tons/hr clinker (24-hour rolling average) 

 1,405,104 ton/yr clinker (any consecutive 12-month period) 

C. Authorized Fuels 

 Authorized fuels may include, but not to be limited to, coal, fuel oil, natural gas, 

petroleum coke, landfill gas, on-specification used oil, whole or shredded tires, 

oily water and other non-hazardous wastes as defined in 40 CFR Part 63, 
Subpart EEE – “National Emission Standards for Hazardous Air Pollutants from 

Hazardous Waste Combustors”. 

 Solid fuel usage limited to 256,000 tons during any consecutive 12-month period 

 Raw mill air heater may only be fired with natural gas, landfill gas, distillate fuel, 

or No. 4 fuel oil. 

 On-specification used oil limited to 4,230 gal/hr and 3 million gallons during any 

consecutive 12-month period. 

D. Technology Requirements 

 Staged and controlled combustion (SCC) and NH3 solution-injection based 

SNCR to reduce NOx emissions. 

 Indirect firing and low NOx burner(s) for reducing NOx emissions. 

 Fabric filters/baghouses to reduce PM/PM10 emissions from process air and/or 

flue gas streams exhausting through vents/stacks. 

 Control of SO2 emissions through equipment design/inherent dry scrubbing, 

judicious selection/use of raw materials, and hydrated lime injection (as 

necessary). 

 Control of CO and VOC emissions through equipment design and combustion 

process management with good operating practices (i.e., adequate combustion 

temperature, residence time and excess air), and judicious selection/use of raw 

materials. 

E. BACT Emission Limits 

Pollutant Operation Emission Limit 

PM 0.153 lb PM/ton clinker 

PM10 0.129 lb PM10/ton clinker 

Visible 

Air Heater, Raw Mill, Preheater/Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: Baghouse 10% opacity 

PM/PM10 0.1 gr/dscf (0.0085 

gr/dscf for PM10) 

Visible 

Finish Mill and all other point sources 

10% opacity 

SO2 Air Heater, Raw Mill, Preheater/Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: Inherent dry scrubbing, raw material 

1.0 lb/ton clinker 

160.0 lb/hr 
Pollutant Operation Emission Limit 

management, hydrated lime injection if 

necessary 

NOx Air Heater, Raw Mill, Preheater/ Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: SCC, SNCR and Low NOx

 burner 

control 

1.95 lb/ton clinker 

312.0 lb/hr 

NOx

(initial 

startup) 

Air Heater, Raw Mill, Preheater/ Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: SCC, SNCR and Low NOx burner 

control 

3.0 lb/ton clinker 

480.0 lb/hr 

CO Air Heater, Raw Mill, Preheater/ Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: Good equipment design and 

combustion processes 

2.9 lb/ton clinker 

464 lb/hr 

VOC Air Heater, Raw Mill, Preheater/ Precalciner, 

Calciner, Kiln, and Clinker Cooler/Main Kiln 

Stack 

Control: Good equipment design and 

combustion processes 

0.5 lb/ton clinker 

80.0 lb/hr 
Initial Topics for the Applicant and Regulatory Authority to Consider for Energy 

Efficiency Evaluations in PSD Permit Applications for Portland Cement Manufacturing 

I. Raw Material Preparation 

 A. Transport Systems 

 Will the proposed facility use pneumatic or mechanical conveyor systems? If the 

plant design specifies pneumatic conveyor systems, what justification is given to 

choose that system over a mechanical system since mechanical systems 

typically use less energy than pneumatic systems? 

 For existing facilities, has a cost analysis been performed for the conversion from 

pneumatic to mechanical systems? 

 B. Raw Meal Blending 

 Will the raw meal blending operation use a mechanical system, air fluidized silos, 

or gravity-type homogenizing silos? Since gravity-type silos typically use less 

energy, what justifications have been provided to select a different system? 

 For existing facilities, has a cost analysis been performed for modifying existing 

silos? 

 C. Raw Material Grinding 

 Does the facility design incorporate the most energy efficiency mills for grinding 

the raw materials? If the design specifies ball mills, what justifications are given 

for not using high efficiency roller mills or high pressure grinding rolls? 

 For existing facilities, has a cost analysis been performed for replacing older 

roller mills? 

 Has the facility considered combining the raw material drying step with vertical 

roller mills by utilizing waste heat from the kilns or clinker coolers? 

 D. Classifiers and Separators 

 Does the facility design incorporate high efficiency (in terms of efficient particle 

separation to reduce the amount of material returned to the grinder) classifiers or 

separators? 

 For existing facilities, has a cost analysis been performed for replacing older, less 

efficient classifiers and separators? 
 E. Fuel (Coal) Grinding 

 If coal is used as a fuel, the same analysis as listed above for raw material 

grinding applies. 

II. Clinker Production 

 A. Process Control and Management Systems 

 New facility designs should incorporate the latest computerized and automated 

control systems to optimize operating conditions in the kiln. 

 There should be few barriers to installing control systems on existing facilities, so 

significant facility modifications should include upgrading these systems. 

 B. Replacement of Kiln Seals 

 Consideration should be given to replacing kiln seals during modifications. 

 New and existing facilities should develop and implement a regular maintenance 

plan for the seals. 

 C. Raw Mix Burnability 

 Does the kiln operation include the use of fluxing agents or mineralizers to 

reduce kiln energy consumption? 

 If so, what alternatives were considered, and did those alternatives lead to 

different levels of energy consumption? What justification is available for why 

one alternative was selected over another (alternatives may be specific to the 

type of product produced)? 

 D. Kiln/Preheater Insulation 

 What refractory material is being used to line the kiln? Does this material provide 

the highest level of insulation available? 

 For existing facilities, are there any structural issues that would preclude the use 

of a heavier refractory material? Can the structural issues be overcome? 

 Is the outer surface of the preheater vessels and cooler housings insulated? 

What is the efficiency of the insulation and are more efficient alternatives 

available? 

 E. Grate Cooler 

 New facilities typically use reciprocating grate coolers because of their higher 

heat recovery efficiency. If planetary or travelling grate coolers are used, a 

justification should be provided as to why reciprocating grate coolers cannot be 

used. 
 For existing facilities, conversion of the grate cooler should be analyzed, 

particularly if the precalciner is being replaced. 

 F. Heat Recovery 

 To what extent is the facility recovering energy from exhaust streams from the 

kiln, clinker cooler, and kiln preheater? Has an analysis been performed to 

determine whether it would be economical to recover the energy in these 

streams through power generation? 

 G. Preheater Cyclones 

 Are low pressure drop cyclones used for preheating the raw meal prior to the 

kiln? 

 At existing facilities, can the cyclones be replaced without a rebuild of the preheat 

tower? Even if a tower rebuild would be required, is the modification cost 

effective? 

 H. Multistage Preheater 

 New facilities should employ four- or five-stage preheaters prior to the kiln. 

Justification should be provided for a new facility that does not include this type 

of preheater. 

 For existing facilities, has a cost analysis been performed on replacing (or adding 

when no preheating is currently used) the preheater without replacing the kiln? If 

kiln replacement is required to make the preheater modification cost effective, 

can the modification be expanded to this level? 

 I. Conversion of Long Dry Kiln to Preheater/Precalciner Kiln 

 For existing facilities without a preheater or with a single- or double-stage 

preheater, consideration should be given to upgrading to a multistage 

preheater/precalciner kiln. 

 J. Kiln Drive 

 Does the facility design incorporate high efficiency motors for the kiln drive? For 

direct drive motors, the highest efficiency is typically obtained with a single pinion 

drive with an air clutch and a synchronous motor. Alternating current motors may 

result in slightly less energy consumption than direct drive motors. 

 K. Adjustable Speed Drive for Kiln Fan 

 Does the facility design for new facilities incorporate an adjustable speed drive 

for the kiln fan so that energy consumption can be reduced when full fan capacity 

is not required? 
 For existing facilities, has a cost analysis been performed for installing an 

adjustable speed drive? 

 L. Oxygen Enrichment 

 Was oxygen enrichment considered in the design of new facilities to increase 

production levels? 

 For existing facilities, was a cost analysis performed to install oxygen 

enrichment? 

 In either case, is there a source of oxygen available at the facility? 

 M. Mid-Kiln Firing 

 For new facilities, does the kiln design allow for mid-kiln firing? If so, was an 

analysis performed for different types of fuels that could be used (for example, 

burning scrap tires may emit less CO2/MMBtu than coal)? 

 N. Mixing Air Technology 

 Does the kiln design incorporate high pressure air injection? If not, was an 

analysis performed on the viability of using air injection to improve combustion 

efficiency? 

 For existing facilities, was a cost analysis performed for modifying the kiln for air 

injection? 

 O. Preheater Riser Duct Firing 

 New facilities will most likely always include a preheater prior to the kiln. The 

preheater design should consider firing a portion of the fuel in the riser duct to 

increase the degree of calcinations in the preheater. 

 For existing facilities, preheater riser duct firing should be considered when 

modifications are made to the preheater or when a new preheater is installed. 

 P. Selective Non-Catalytic Reduction 

 Although SNCR is a NOx control technique, the process includes injection urea 

or ammonia into the kiln near the flame end, which in certain situations may 

reduce fuel CO2 emissions. This option should be considered when NOx co

is required

ntrol 

. 

III. Finish Grinding 

 A. Milling Operations 

 Does the design of the finish grinding operation include roller presses or roller 

mills in combination with a ball mill to reduce energy consumption? 
 The same analysis as listed above for raw material grinding applies. 

 B. Classifiers 

 The same analysis as listed above for classifiers and separators applies. 

IV. Facility Operations 

 A. Blended Cement 

 Did the facility design consider the use of supplementary cementitious materials 

(such as blast furnace slag, fly ash from coal combustion, and natural pozzolans) 

to replace a portion of the clinker production? 

 B. Motors 

 Cement manufacturing facilities may include 500-700 motors. A motor 

management plan should be implemented that evaluates factors such as 

strategic motor selection, maintenance, proper size, adjustable speed drives, 

power factor correction, minimization of voltage unbalances. 

 Variable speed drives should be considered where load conditions may vary. 

 C. High Efficiency Fans 

 New facilities should use the latest designs in high efficiency fans that reduce 

energy consumption. 

 Existing facilities should evaluate upgrading fans to modern designs. 

 D. Compressed Air Systems 

 A comprehensive maintenance plan should be implemented for the compressed 

air system, including repair of leaks. 

 The air inlet should be located at the coolest point possible. 

 Recovery of the heat generated by the compressor should be evaluated. 

 E. Lighting Systems 

 Does the facility design incorporate energy efficient lighting systems and 

automated lighting controls? 

 F. Alternative Energy Sources 

 Can alternative energy sources such as solar panels be used to supply a portion 

of the plant’s electricity needs? 

 
G. Other Conservation measures 

 In general, what energy conservation measures were incorporated into the plant 

design?