Clay bricks for blast furnaces and hot blast stoves
Clay bricks for blast furnaces and hot stoves are made from clay (including shale, gangue and other powders) as the main raw materials, which are treated, molded, dried and roasted with mud. During the Spring and Autumn Period and the Warring States Period, China successively created square and rectangular bricks. In the Qin and Han Dynasties, brick-making technology and production scale, quality and variety of patterns have been significantly developed. The size of ordinary bricks is 240 mm *115 mm *53 mm. According to the compressive strength (Newton/square millimeter, N/mm2), they are divided into six strength grades: MU30, MU25, MU20, MU15, MU10 and MU7.5. Clay brick is widely used in civil engineering because of its low price, durability, fire protection, heat insulation, sound insulation, moisture absorption and other advantages. Scrap bricks can also be used as aggregate for concrete. In order to improve the shortcomings of ordinary clay brick, such as small size, self-weight and high soil consumption, it is developing towards the direction of light weight, high strength, hollow and large block. The lime-sand brick is made of lime, quartz sand, sand or fine sandstone in proper proportion, which is ground, mixed with water, pressed and cured by autoclave. Fly ash brick is made of fly ash as the main raw material, mixed with coal gangue powder or clay and other cementing materials, through mixing, molding, drying and roasting. It can make full use of industrial waste residue and save fuel.
China's clay brick Al2O3 content is generally more than 40%, Fe2O3 content is less than 2 to 2.5%. The clinker is 65 to 85%, and the clay is 35 to 15%. The crushed bonded clay and fine clinker are mixed and grinded, and then mixed with granular clinker to make semi-dry mud. The semi-dry mud is formed under high pressure and fired at about 1400 C. The performance is good. The clay brick is weak acidic at high temperature, and its resistance to alkaline slag corrosion is slightly poor, but it increases with the increase of Al2O3 content. Thermal stability is better than silica brick, magnesia brick (see magnesia brick) and so on.
The qualified clay bricks of blast furnace were dried and impregnated with phosphoric acid in vacuum and sintered at low temperature twice. The products were used for lining the upper part of blast furnace body.
refractoriness， ℃ ≥
refractoriness underload (0.6%) ≥，℃
linear under load，%
App. porosity， % ≤
C. C. S， MPa ≥