7 Steps of the Fire Clay Bricks Manufacturing Process

The fire clay bricks manufacturing process can be divided into 7 steps:

(1) Get earth. The earth for producing fire clay bricks is gotten from the ancient soil Two feet deep under the ground surface. The color of soil in this layer is slightly deeper than the ground surface soil. It was formed about 80,000 to 120,000 years ago. At that time, the Earth was warm and humid. Rich biological resources make the soil formed during this time soft and sticky and a good material for manufacturing fire clay bricks. 

(2) The clay earth should be piled in the open air to expose to sunlight, cold, snow and rain erosion for 6 months to make the soil decomposed and softened. Then it is crushed by hand and screened to get the pure fine soil. 

(3) Add water to the soil. Then refine or stampede repeatedly to make it into thick mud. Repeat this for 5-6 times. This step is important for the quality of bricks. 

(4) Fill mud into wood molds and then compact it tightly. Remove the excessive mud with iron wire bows. Before filling the mud, sprinkle a layer of sand on the ground under the wood mold to prevent adhesion of mud to the ground. 

(5) The green body is released and then placed away from the sun to prevent cracks and deformation caused by the exposure. 

(6) After completely dried (about 1 or 2 months), the bricks are loaded into the kiln. This step is the most important step during the manufacturing process. For common bricks, the kiln is fueled with coal, while for dense filter pulp bricks, the kiln is heated with straw and pine. 

(7) After tens of days of firing, the green body has been sintered. If puttering out, external air will enter the kiln and the green body turns red after cooled. The green bricks should be rusted in the kiln by sealing the ventilation holes in the crown when heating the bricks at high temperature. The reducing of external air transforms the atmosphere of the kiln into a reducing atmosphere. Thus, high-valence red iron oxides are reduced to low-valence gray iron oxides. In order to prevent the re-oxidation of low-valence iron oxides, seal the holes in the crown to make water absorb heat and heated into steam. During this cooling process, the kiln is maintained a reducing atmosphere until the bricks are completely cooled and out of the kiln.