Mining
The process of manufacturing brick begins with the selective mining of clay and shale. This material is hauled from our mines to the plant to be processed.
Manufacturing
Processing Raw Materials
The raw material is processed through a primary crusher, secondary grinder, and then screened to assure uniform particle size distribution for consistent structural integrity and color of the brick. After the material is ground, it is conveyed to the pugmill to be vacuum extruded. Following the extrusion process, the green brick is cut to size and automatically set onto kiln cars for drying and firing.
Drying and Firing Brick
Kiln cars enter the dryer where the water is removed before firing can begin. The brick then move into the kiln and are carefully brought to temperatures exceeding 1900 degrees Fahrenheit. A glassy phase forms around the clay particles fusing them together to form a strong durable brick.
Sorting and Blending Brick
Once the brick have cooled, they are ready to be packaged for shipment. The brick are manually sorted and blended then banded and labeled ready to be put on a truck for shipment.
Where do all of the different colors of brick come from?
Bowerston Shale uses various methods to create different colors of brick:
- Various clays and shale naturally produce different colors. Blending different ratios of these raw materials will also yield different shades.
- Flashing or injecting raw gas into the kiln is a heat treatment that creates color differences. The raw gas ignites and depletes the kiln atmosphere of oxygen, creating a reducing atmosphere. Certain minerals in the brick give up oxygen in a reducing atmosphere at high temperature producing various shades of color by changing the chemical structure of the brick.
- Adding minerals to clay and shale will create shades of browns, buffs, and grays.
- After the brick are extruded, sand coatings and slurries can be applied to the unfired brick surface to create an infinite amount of different color varieties.