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 in formation on sources of hazardous air pollutant (HAP) emissions and emission controls in supp ort of the redevelopmen t of national emission standards for hazardous air pollu tants (NESHAP) for the brick a nd 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 242

Matthew Berry, Assistant Pl ant 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 Monc ure facility consists of two plants: Plant 24,

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

called the Brickhaven Plant. Plant 24 incl udes a central crushing, grinding, and screening operation which provides material for both plan ts, brick forming operations, and two sawdustfired tunnel kilns (Kilns 1 and 2). The saw dust-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 tunn el 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 k iln was brought on line in 2005. However, due to the rising natural gas prices, Gene ral Shale switched both kilns to coal firing in 2007. The coalfired tunnel kilns each have a pr oduction 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 da ys per week: brick forming takes place during two 8-hour shifts and operates 5 days pe r week, firing operations operate continuously,3

while the mining and raw material operations op erate 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 br icks 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 automa tion; in Plant 25, much more of the equipment is automated than in Plant 24. Th e process steps include raw material storage, mixing, forming, drying, and firing. The followi ng 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 form ing 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 materi al is vacuum-extruded from the pug mill as a continuous column onto an open conv eyor belt. The next step is cutting. One process line uses a reel cutter, and the other uses a push-through type of cutter to cu t 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 manuall y stacked onto kiln cars for drying. Prior to stacking, the green bricks may be “tumbled” by a llowing the bricks to fall from one conveyor onto a lower conveyor. Tumbling gives the finished product a de liberately worn appearance. After tumbling, the bricks are manually straight ened and continue along the conveyor to the stacking area.

After the bricks are cut, but prior to tumbling, a co loring agent and sand may be applied to the outside of the gree n bricks to give the finished pr oduct 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 (con taining no products of combustion) from the cooling zones of the

kilns. The kiln cars th en are mechanically rolled out of the dryers and into one of the two tunnel kilns, where they are fired.4

As noted above, the kilns in Plant 24 are fired with sawdus t. The sawdust is received by truck and stored initially outsi de in stockpiles. From the outside piles, the sawdust is

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

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

Undersize material is transferred from the scr eening operation to a rotary sawdust dryer. The rotary dryer operates at an inle t temperature of approximately 260  C (500  F), and is heated by the kiln exhaust, which is routed through the sa wdust dryer and then emitted to the atmosphere.

The dried sawdust is carried in the exhaust stream from the drye r to two cyclones in parallel, which recover the dried material. The cyclone e xhaust 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 k iln. After cooling, the ca rs exit the kiln and are rolled outside the kiln to an unloading area. There, the bricks are manually unloaded from kiln cars, packaged, and trans ported to an open storage area outside th e covered plant. The entire kiln cycle takes approximately 3 days to complete.

2. Plant 25. Plant 25 includes one brick fo rming line, six green brick dryers, and two tunnel kilns. The process used in this plant is similar to the br ick manufacturing process that is used in Plant 24. However, Plan t 25 is largely automated, so mo st of the manual operations that are performed in Plant 24 are pe rformed robotically in Plant 25. The other primary differences between the two plants are associat ed 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. Over size material is returned to the impact mill for further size reduction, and undersize ma terial is transferred pneumati cally 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 simila r to the process step s 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 theexhaust stream. The original NESHAP, which was promulgated in 2004, exempted sawdustfired kilns from control. Consequently, the f acility was not required to install any additional

emission controls on Kilns 1 and 2 in Plant 24. Em issions from the coal-fired kilns (Kilns 3 and 4) are exhausted to dedicated dry limestone ad sorbers (DLAs). The DLAs were installed to5

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 mate rial 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 mate rial 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 a ddition, the facility obtai ned approval to monitor

the limestone levels in the DL A 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 bi n, as required by the or iginal 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.