Refractory industry, from the point of view of appearance all know what is the clay brick, what is the high alumina brick, but if you let him say, where is the difference between the clay bricks and high alumina bricks, but a lot of people don't know, don't know that people will notice, foshan huanya refractory plant to help you to solve, more or less will have the help to you, if you have not clear not understand place,Please contact: Manager Zheng at +86-17328087470.
1. Clay brick
Clay brick refers to the Al2O3 content of 30%~50% aluminum silicate clay products.Clay brick is made of 50% soft clay and 50% hard clay clinker, batching according to certain particle size requirements, after molding, drying, fired at 1300~1400℃ high temperature.The mineral composition of clay brick is mainly kaolinite (Al2O3·2SiO2·2H2O) and 6%~7% impurities (oxides of potassium, sodium, calcium, titanium and iron).The sintering process of clay brick is mainly the process of kaolinite's continuous water-loss decomposition to mullite (3Al2O3·2SiO2) crystallization.SiO2 and Al2O3 in clay brick form eutectic low melting point silicate with impurity during sintering, which surrounds the mullite crystal.
Clay brick belongs to weak acid refractory products, can resist the erosion of acid slag and acid gas, the resistance ability of alkaline material is slightly poor.The thermal property of clay brick is good, and it is resistant to cold and heat.
The refractoriness of clay brick is similar to that of silicon brick, up to 1690~1730℃, but the softening temperature under load is more than 200℃ lower than that of silicon brick.Because in addition to containing high refractoriness of mullite crystals, clay brick also contains nearly half of the low melting point amorphous glass phase.
In the temperature range of 0~1000℃, the volume of clay brick expands uniformly with the increase of temperature. The linear expansion curve is approximately a straight line, and the linear expansion rate is 0.6%~0.7%, which is only about half of that of silicon brick.When the temperature reaches 1200℃ and then continues to rise, its volume will shrink from a larger expansion value.The residual shrinkage of clay brick leads to the loosening and cracking of masonry ash joints, which is a major drawback of clay brick.When the temperature exceeds 1200℃, the low melting point materials in the clay brick melt gradually, and the particles are very close to each other due to the action of surface tension, resulting in volume contraction.
Because of the low softening temperature under the load of clay brick, shrinkage under high temperature, thermal conductivity is 15%~20% smaller than the silicon brick, the mechanical strength is also worse than the silicon brick, so clay brick can only be used in the secondary parts of coke oven, such as the sealing wall of the regenerative chamber, small flue lining brick and regenerative chamber grid brick, furnace door lining brick, furnace top and rising pipe lining brick.
2. High aluminum brick
High alumina brick is Al2O3 content greater than 48% of aluminum silicate or alumina refractory products, collectively referred to as high alumina refractory products.The refractory degree and softening temperature under load of high aluminum brick are higher than that of clay brick, and the slag corrosion resistance (especially to acid slag) is better, and these properties increase with the increase of Al2O3 content, but the thermal stability of high aluminum brick is not as good as that of clay brick.High alumina brick has high density, low porosity, high mechanical strength and wear resistance.The furnace head of the coke oven combustion chamber and the bottom brick of the carbonization chamber are constructed by high aluminum brick, which has better effect.But it is not suitable for the wall of the carbonization chamber, because the high aluminum brick is easy to produce curling Angle at high temperature.In the actual production, due to the different resource conditions and product requirements, the following types of raw materials can be used: to water containing aluminum oxide minerals (diaspore, triaspore, etc.) high alumina brick as the main composition of high alumina;Sillimanite group minerals (including kyanite, andalusite, sillimanite, etc.);Synthetic raw materials, such as industrial alumina, synthetic mullite, fused corundum, etc.China is rich in high alumina vanadium soil resources and good quality, and its producing areas are mainly distributed in Shanxi, Henan, Hebei, Guizhou, Shandong and other places.The high-aluminium-vanadium soil produced is mainly a mixture of diaspore (α-Al2O3·H2O) and kaolinite.High alumina brick is mainly used for the lining of blast furnace, hot blast furnace, top of electric furnace, blast furnace, reflection furnace and rotary kiln.In addition, high alumina brick is also widely used as open hearse regenerative lattice brick, plug head for gating system, nozzle brick, etc.But the price of high aluminum brick should be higher than clay brick, so the place that can satisfy the requirement with clay brick need not use high aluminum brick.
