Clay is a common mineral, which consists of extremely fine rock particles. Some kinds of clay are formed by weathering and cracking of rocks. Clay exists in most areas of the earth's surface, especially in lake beds and river beds. Clay is slippery and elastic when it is wet. When it dries, it will become as hard as a stone. If clay is heated at high temperature, it can be made into bricks.
Ancient people found that fired clay bricks would not soften and deform when exposed to water. When the temperature of the brick is high enough, the color of the brick turns red, and then the higher the temperature, the darker the color. Therefore, after the replacement of dynasties and the improvement of social productivity, the brick-making technology has become more and more mature, and the bricks in the palaces of court nobles have also been decorated by craftsmen in various ways, including dragon patterns, phoenix patterns and sun patterns. The Great Wall of Wan Li built by the famous Qin Shihuang is made of bricks. This project is costly and large-scale. Thousands of bricks were used. History has proved that the brick-making technology used by Qin Shihuang at that time was superb, which made the Great Wall of Wan Li still exist.
Brick-burning technology has not changed much since ancient times, but modern brick-burning technology has been mechanized. People first dug up clay with a mechanical shovel. After drying in the sun, it is ground by a mill, and then the particles with certain specifications are screened out by a sieve, and then mixed with water to form a thick mud, and then the mud is extruded through a die, just like a huge square toothpaste strip. Then the machine cuts these strips into small pieces of various specifications with a knife or wire. These soft bricks are dried in the heating tube, finally put on the conveyor belt, and sent directly to the brick kiln to be roasted into finished bricks.