The manufacturing process of low porosity clay brick mainly includes the following key steps:

I. Preparation of raw materials

The main raw materials of low porosity clay brick include flint clay clinker, low alumina mullite, soft clay, binder (such as phosphoric acid or phosphate) and other additives. These raw materials need to be strictly screened to ensure their high purity and few impurities.

II. Crushing and grading of raw materials

Flint clay clinker, low alumina mullite and other main raw materials are crushed into particles with different particle sizes, such as 5-3mm, 3-1mm and ≤0.088mm respectively. Through reasonable classification, the compactness and strength of brick can be optimized.

III. Mixing and stirring

Mix the crushed raw materials with binders, additives, etc. according to a certain proportion, and fully stir them evenly. In the process of stirring, the control of temperature and time is also very important, for example, the stirring temperature is usually 150℃-250℃ and the stirring time is 0.5-1 hour.

IV. Molding

The mixed blanks are put into high-pressure forming equipment, usually using a 260T friction brick press, and molded into bricks with standard bricks. In the molding process, the green brick will be hit many times (such as 6-8 times) to ensure its density and strength.

V. Drying

The formed green bricks need to be dried in a drying kiln, usually at 110℃-160℃ for 6-10 hours. During the drying process, it is necessary to ensure that the moisture content of the brick is lower than 1% to prevent cracks from appearing during the firing process.

VI. High temperature sintering

The dried green bricks are put into a tunnel kiln for high-temperature sintering, the sintering temperature is usually 1400℃-1500℃, and the duration is generally 10-15 hours. Properly increasing the sintering temperature can further reduce the porosity and improve the density and strength of the brick.

VII. Quality inspection

After sintering, each brick needs to undergo strict quality inspection, including porosity, bulk density, compressive strength, load softening temperature and other indicators. Only products that meet the standards can leave the factory.

VIII. Packaging and storage

Qualified clay bricks with low porosity will be packaged, usually using trays and fixed with PET tape, and covered with plastic film to prevent damage during transportation.

Through the above steps, low porosity clay bricks can maintain high strength and stability in high temperature environment, and are widely used in high temperature kilns in metallurgy, glass, chemical industry and other industries.