Date: August 18, 2008 

 (Finalized: December 12, 2008) 

Subject: Site Visit -- General Shale Brick, Inc., Moncure, North Carolina 

Brick and Structural Clay Products Manufacturing NESHAP 

EPA Contract No. EP-D-06-118; EPA Work Assignment No. 2-09 

RTI Project No. 0210426.002.009 

From: Richard Marinshaw 

 Tom Holloway 

Gabrielle Raymond 

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 brick manufacturing process at the 

General Shale Brick facility and to collect information on sources of hazardous air pollutant 

(HAP) emissions and emission controls in support of the redevelopment of national emission 

standards for hazardous air pollutants (NESHAP) for the brick and structural clay products 

industry. 

 II. Place and Date 

General Shale Brick, Inc. 

 300 Brick Plant Road 

 Moncure, North Carolina 27559 

 July 29, 2008 

 III. Attendees 

 

 General Shale 

 

 Warren Paschal, Manager of Environmental Compliance 

Telephone: (919) 774-5306 

Jeff Magee, Assistant Plant Manager, Plant 24
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Matthew Berry, Assistant Plant Manager, Plant 25 

The Brick Industry Association (BIA) 

Joe Casper, Vice President, Environmental 

Telephone: (703) 674-1545 

Terry Schimmel, BIA MACT Task Force Lead 

(Boral Bricks, Inc.) Telephone: (334) 480-2488 

 U. S. Environmental Protection Agency 

 Jeff Telander 

 Telephone: (919) 541-5427 

 RTI International 

 Tom Holloway 

 Telephone: (919) 316-3733 

 

 Richard Marinshaw 

 Telephone: (919) 316-3735 

 Gabrielle Raymond 

 Telephone: (919) 541-7015 

 IV. Discussion 

 A. Background 

 The General Shale Brick, Inc. (General Shale) facility, located in Moncure, North 

Carolina, manufactures structural bricks. The Moncure facility consists of two plants: Plant 24, 

which is also referred to as the Cape Fear Plant or the Sawdust Plant; and Plant 25, which is also 

called the Brickhaven Plant. Plant 24 includes a central crushing, grinding, and screening 

operation which provides material for both plants, brick forming operations, and two sawdustfired tunnel kilns (Kilns 1 and 2). The sawdust-fired tunnel kilns each have a production 

capacity of 13.7 tons of fired brick per hour (ton/hr). Plant 24 has been operating since the late 

1950's. Plant 25 includes brick forming operations and two coal-fired tunnel kilns (Kilns 3 and 

4). When Plant 25 originally went on line in July 1996, the plant operated a single natural gasfired tunnel kiln. A second natural gas-fired kiln was brought on line in 2005. However, due to 

the rising natural gas prices, General Shale switched both kilns to coal firing in 2007. The coalfired tunnel kilns each have a production capacity of 20.55 ton/hr of fired brick. Both plants use 

natural gas as a back-up fuel for the kilns. 

 The facility operates 24 hours per day, 7 days per week: brick forming takes place 

during two 8-hour shifts and operates 5 days per week, firing operations operate continuously, 
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while the mining and raw material operations operate 5 days per week, or as needed depending 

on the production schedule. General Shale has more than 500 employees nationwide. 

 B. Process 

 General Shale manufactures structural bricks in both plants, and the same basic 

process is used for producing bricks at each of the plants. The primary differences between the 

two plants is the type of kiln fuels used and the degree of automation; in Plant 25, much more of 

the equipment is automated than in Plant 24. The process steps include raw material storage, 

mixing, forming, drying, and firing. The following paragraphs describe structural brick 

production in more detail. Attached is the non-confidential handout provided by the BIA at the 

start of the site visit. 

 The raw material used by General Shale is Triassic shale. The shale is mined with 

dozers and pans and stored in stockpiles at the active mine located approximately 2 miles from 

the plant. The material is then trucked to the grinding room located at Plant 24, where the 

material is emptied into a hopper and fed to one of two hammer mills. From the hammermills, 

the material is conveyed to vibrating screens. Oversize material is routed back to the 

hammermills, and undersize material is conveyed to covered storage piles. 

 The following paragraphs describe the operations performed in the two plants. 

Plant 24 is described first, followed by the description of Plant 25. 

 1. Plant 24. Plant 24 operates two brick forming lines. The raw material is conveyed 

from storage to one of the processing lines. The material is fed into a pug mill, where the raw 

material is mixed with water. The material is vacuum-extruded from the pug mill as a 

continuous column onto an open conveyor belt. The next step is cutting. One process line uses a 

reel cutter, and the other uses a push-through type of cutter to cut the column into slugs, which 

are then further cut by wire into individual “green” bricks. The green bricks travel by conveyor 

to the stacking area, where the bricks are manually stacked onto kiln cars for drying. Prior to 

stacking, the green bricks may be “tumbled” by allowing the bricks to fall from one conveyor 

onto a lower conveyor. Tumbling gives the finished product a deliberately worn appearance. 

After tumbling, the bricks are manually straightened and continue along the conveyor to the 

stacking area. 

 After the bricks are cut, but prior to tumbling, a coloring agent and sand may be 

applied to the outside of the green bricks to give the finished product a certain color and texture. 

Prior to use, the sand is dried in a rotary dryer. 

 The kiln cars loaded with green bricks are next rolled down a track into one of four 

dryers, which operate at temperatures between 120 to 150C (250 and 300F). The dryers 

are heated with waste heat (containing no products of combustion) from the cooling zones of the 

kilns. The kiln cars then are mechanically rolled out of the dryers and into one of the two tunnel 

kilns, where they are fired. 
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 As noted above, the kilns in Plant 24 are fired with sawdust. The sawdust is received 

by truck and stored initially outside in stockpiles. From the outside piles, the sawdust is 

transferred to one of two wet sawdust silos. From the silos, the wet sawdust is screened. 

Oversize material is transferred to a hammermill, then back to the screening operation. 

Undersize material is transferred from the screening operation to a rotary sawdust dryer. The 

rotary dryer operates at an inlet temperature of approximately 260C (500F), and is heated by 

the kiln exhaust, which is routed through the sawdust dryer and then emitted to the atmosphere. 

The dried sawdust is carried in the exhaust stream from the dryer to two cyclones in parallel, 

which recover the dried material. The cyclone exhaust is ducted to two parallel stacks. The 

recovered sawdust is conveyed to the dry sawdust storage silo. 

 After drying, the kiln cars loaded with green bricks are pushed through the kiln 

according to a set schedule. The temperature within the kilns varies along the length of the kiln. 

From the entrance, the temperatures within the kiln are ramped up to a maximum in the firing 

zone, which is maintained between 1040 and 1090C (1900 and 2000F). From the firing 

zone, the bricks enter the cooling zone of the kiln. After cooling, the cars exit the kiln and are 

rolled outside the kiln to an unloading area. There, the bricks are manually unloaded from kiln 

cars, packaged, and transported to an open storage area outside the covered plant. The entire kiln 

cycle takes approximately 3 days to complete.

 2. Plant 25. Plant 25 includes one brick forming line, six green brick dryers, and two 

tunnel kilns. The process used in this plant is similar to the brick manufacturing process that is 

used in Plant 24. However, Plant 25 is largely automated, so most of the manual operations that 

are performed in Plant 24 are performed robotically in Plant 25. The other primary differences 

between the two plants are associated with the types of fuel used to fire the kilns. Instead of 

using sawdust to fire the kilns, the kilns in Plant 25 are fired with coal. 

 Plant 25 uses a low-ash, low-sulfur coal that requires no additional cleaning on site. 

Coal consumption for the plant is approximately 26 tons per day. The coal is shipped by truck 

and transferred to covered storage bins. Next the coal is dried then crushed in an impact mill. 

From the impact mill, the coal is screened. Oversize material is returned to the impact mill for 

further size reduction, and undersize material is transferred pneumatically to storage and then to 

one of two kilns for firing. As noted above, the other process steps (e.g., mixing, extruding, 

cutting, drying, firing, and packaging) are similar to the process steps described above for 

Plant 24. 

 C. Emissions and Controls 

 The primary emission units are the kilns. Emissions from the sawdust-fired kilns 

(Kilns 1 and 2) are exhausted to the sawdust dryer, which captures some of the pollutants in the 

exhaust stream. The original NESHAP, which was promulgated in 2004, exempted sawdustfired kilns from control. Consequently, the facility was not required to install any additional 

emission controls on Kilns 1 and 2 in Plant 24. Emissions from the coal-fired kilns (Kilns 3 and 

4) are exhausted to dedicated dry limestone adsorbers (DLAs). The DLAs were installed to 
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comply with the original NESHAP, which was subsequently vacated. The operation of the 

DLAs is described in the following paragraph. 

 Limestone is fed into a reaction chamber at the top of the DLA at a feed rate setting 

equivalent to 110 pounds per hour. The limestone cascades through multiple baffles within the 

chamber and reacts with the exhaust gases from the kiln, which flow across the reaction 

chamber. When the limestone reaches the bottom of the chamber it is transferred by augur to a 

peeling drum, which removes the reacted material on the surface of the limestone. The 

processed limestone is then conveyed pneumatically back to the top of the reaction chamber. 

New limestone is periodically added to the system as needed, as reacted limestone is removed. 

Waste material from the DLAs is either shipped off-site for agricultural applications or used as 

road filler or surface material within the plant. 

 The DLAs operate at a very low pressure drop, so the facility obtained approval from 

the State of North Carolina to monitor bypass damper position as an alternative to the pressure 

drop requirement in the original NESHAP. In addition, the facility obtained approval to monitor 

the limestone levels in the DLA hopper and storage bin (surge bin) using an automated highmedium-low recording system, rather than having to climb to the top of the DLA to perform a 

daily visual check of the hopper and storage bin, as required by the original NESHAP. The 

facility also periodically monitors the limestone feed rate setting for the DLA. 

 The sawdust hammermill and handling system is exhausted to a cyclone, which 

serves primarily as a product recovery device. As noted above, the cyclones on the sawdust 

dryer exhaust system serve as product recovery devices.