Clay brick manufacturing process Part one
Winning
Heavy earthmoving equipment such as bulldozers, scrapers and mechanical shovels are used to extract the clay and shales.
Crushing and blending
After being transported from the pit by truck or endless conveyor, the materials are stockpiled to enable blending of the various types of clay
The clays are fed separately by hopper or conveyor to the primar y crushers – in South Africa rolls or hammer mills are commonly used. These reduce the particle size down to 3 – 5 mm or less. The mixing of clays follows, to impart the desired properties, such as colour and strength.
Grinding
Conveyors carry the mixed clay away for secondary crushing, which is usually done by means of a pan mill. The pan mill has two heavy steel wheels on an axle that is connected to a central vertical spindle around which they rotate, crushing the clay against the base of the pan.
The base is perforated to allow the crushed material to fall through. This process, when done with dry clay, shatters the brittle particles into smaller pieces. When the pan mill is used with wet clay, the plastic material is squeezed through the perforations and then falls between highspeed rollers which complete the grinding process.