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There are about five different steps in a typical brick manufacturing process, which begins with gathering the proper materials and ends with an application of high heat. Bricks are typically made from a mixture of sand and clay that contains small amounts of lime, iron oxide, and magnesia. These materials are mixed together with water and are then pressed into forms or extruded. After the raw materials have been formed into brick shapes, they are typically allowed to dry for a set amount of time. The final step in the brick manufacturing process is to subject the bricks to extreme heat, which has the effect of removing most of the remaining water content.
Bricks are ceramic blocks that are a common component of masonry construction projects. The earliest bricks have been dated to at least 7500 BCE, and the precise methods of brick manufacturing have changed somewhat throughout the centuries. Brick manufacturing was once a task that involved a great deal of manual labor, as the clay had to be extracted and prepared by hand. This is the first step in the process of brick manufacturing, and it involves removing all large rocks and other inconsistencies from the clay. By the 19th century this preparation often took place in horse powered pug mills, and modern brick manufacturers typically use automated machinery to accomplish the same task.
After the raw materials have been mixed together, the next step in brick making is the molding process. This was originally accomplished by pressing the clay into forms by hand, though a number of techniques are in use today. Extruded bricks are forced through an aperture and then cut with wires. This method is often used to create bricks that contain holes or other void spaces. Bricks can also be molded with steel forms and hydraulic presses.
Before green bricks can be fired in a kiln, they must be allowed to dry. Failure to do so can destroy the bricks, or result in a substandard product. Industrial operations sometimes use specialized drying equipment, or place the green bricks in close proximity to kilns that are undergoing the cooling process. This can take up to two days, depending on the physical makeup of the bricks.
After the green bricks contain a low enough percentage of moisture, they can undergo a firing process. Modern brick manufacturing operations sometimes make use of rail kilns, which allow for continuous operations. Carts loaded with bricks slowly pass through this type of kiln, and undergo the entire heating and cooling process in one continuous motion. Other operations use kilns that are brought up to the correct temperature, then allowed to cool down before the bricks are removed.