BUILDING MATERIALS: BriCks

The brick manufacturing process

The process of making bricks consist of following steps: raw material preparation, the forming process, setting and drying and firing.

Raw material preparation

Extration of the raw material from quarry and its transportation to storage area, by conveyor belt or road transport

remove top soil and unsuitable burden

screen raw material to remove any rocks

ground into powder by crushers or rollers with further screening to remove small particles.

crushing

storage area

Gathering raw material

screening

pug mill

Forming process

handmade brick-----a soft mixture is forced through an extruder, cut into slugs and conveyed to work stations. The slugs are then individually picked up, rolled in sand and thrown into a pre-sanded wooden mold by a worker. Excess raw material is removed by a wire and endless belt. As the filled mold boxes continue on their journey, they are mechanically bumped on their ends to loosen the brick from the mold prior to dumping.
soft mud process------made from shale or clay material that is pugged or mixed with considerable water and placed in a machine that presses the wet mix into molds previously sanded. The mold boxes are then bumped and dumped. A variety of sands are used to keep the brick from sticking in the molds and to affect different textures and colors of the final product.
extruded wire-cut process-------- The shale and clay materials for extruded brick are mixed with a moderate amount of water. This mixture is forced by means of an auger through a die having the shape of the brick. Prior to entering the die, the material passes through a vacuum changer that reduces the amount of air in the mix resulting in a denser, more homogeneous product. It is here that core holes are placed in the column. The core holes are needed to reduce the mass for firing and the weight for future handling. The column that is produced by the extruder is cut by wires to make individual brick. Scratching, scraping, rolling or sanding the surface of the column as it exits the die produce multiple textures on the face of the brick.

Handbrick making


extruder

cutter for slice brick

clay in mold box

handbrick shape

sliced extruder birck

Drying & Firing

Drying----- the bricks are hand or mechanically set onto kiln cars. Prior to entering the kiln, the unfired or green brick must be properly dried. This is an extremely important part of the manufacturing process. Moisture in the brick must be limited at this time to prevent scumming and certain mechanical defects from occurring when the brick is subjected to the intense heat of the kiln. Generally, the drying process is done by placing the green brick in enclosed dryers which utilize excess heat from the cooling kiln.

Firing------green brick pass through the long length of the kiln on a continuous procession of cars moving on rails, much like a small railroad train. The continuous tunnel kiln employs a combination of vertical and horizontal drafts. The preheating, burning and cooling is done in zones varying in temperatures up to 2,000 degrees. In this type of kiln, closer temperature control is possible and less handling of the green brick results in better quality products.When the green brick enters the kiln, the manufacturer determines the type of firing required to produce the desired range of color. If a range of clear burn color is wanted, a straight burn from start to finish produces the desired result. The only color variations being the extremes of dark color nearest the fire or in the crown on the kiln and the light color at the bottom where the brick have the lowest temperature. The remainder of the brick will have medium tones. However, if the kiln is designated to be flashed, the dampers are regulated at the end of the burn to cut off the air and subject the brick to a reducing fire, thus bringing out the blacks, blues, browns, etc. which make up a flashed range.