Phosphated high-alumina composite brick is a common type of new dry-process cement kiln brick, referred to as high-alumina phosphorus brick or phosphate brick. Phosphate brick products are high-alumina refractory products made of high-alumina bauxite clinker as the main raw material, phosphoric acid or aluminum phosphate as a binder, high-pressure molding, and heat treatment at 600°C. Phosphate high-alumina bricks have good thermal stability. When the temperature of the cement kiln lining changes sharply, phosphate high-alumina bricks will not burst, peel or collapse. And it is easy to hang the kiln skin, high wear resistance, and long service life.
Phosphate high alumina bricks are widely used in cement kilns and can be used in preheating zones, decomposition zones, transition zones and cooling zones. Cement kiln firing zones with a diameter of less than 3 meters can also be used as linings.
The building materials industry standard JC350-1993 “Phosphate-bonded high alumina bricks for cement kilns” is divided into two types according to the binder. The binder concentration of phosphate high alumina bricks is 50% of 42.5% phosphoric acid solution. The code is P, and the lock seam brick code is PC. Aluminum phosphate bonded high alumina wear-resistant bricks (abbreviated as wear-resistant bricks). The binder is an aluminum phosphate solution made of industrial phosphoric acid and industrial aluminum hydroxide. The molar ratio is: Al2O3:P2O5=1:3.2, codenamed PA.
Phosphate-bonded high alumina bricks have high thermal strength, good thermal shock resistance, strong wear resistance, and are easy to hang kiln skin. Some cement plants use them in the firing zone and transition zone of small rotary kilns. When the kiln is frequently started and stopped during the commissioning phase, it shows good performance.
In the past decade, a lot of research has been conducted around the basic process route of phosphoric acid bonding. For example, increasing the amount of clay added to the ingredients or adding silicon powder to balance the deficiencies caused by the transformation of AlPO4 crystal form. Introducing kyanite, sillimanite, and zircon into the ingredients to increase the load softening temperature (high load soft phosphoric acid bricks). Adding Guangxi white mud to phosphoric acid and mixing it into mud, using the mud as a binder, can make the material soften. These technical measures are all effective.
Application of Silicon Carbide Mullite Bricks in the Transition Zone of Cement Kilns
The process characteristics of the transition zone determine that the kiln skin changes frequently, so the spalling resistance of refractory materials is required to be high. In addition, as the liquid phase begins to appear in this area, the heat load of the refractory bricks also increases. Without the kiln skin, this brick also needs better chemical corrosion resistance and wear resistance.
After comparing the performance of various refractory bricks, Rongsheng Refractory Material Manufacturer began to study AZM silicon carbide mullite bricks. Its chemical composition is mainly Al2O3 and SiO2, with small pores, resistance to sulfur and alkali corrosion, thermal shock and strength, etc. are better than other physical and chemical indicators. The magnesia-iron spinel bricks produced by Rongsheng Refractory Material Manufacturer also have good kiln skin performance.
Low thermal conductivity corundum silicon carbide mullite bricks are active calcium oxide and high-end refractory bricks for dynamic rotary kilns.
Physical and chemical indicators:
High load softening temperature, greater than 1650℃, high temperature resistance and erosion resistance.
Good kiln skin, better than phosphate bricks and will not form large rings.
Good erosion resistance and wear resistance, its wear resistance is not greater than 4.5.
High compressive strength, its room temperature compressive strength is not less than 110MPa.
Good thermal shock stability, 1100℃×water cooling times>15 times.
Main performance:
Energy saving and environmental protection. It is applied to the rotary kiln firing zone and can reduce the cylinder temperature below 300℃. The energy-saving effect is obvious and can reduce energy consumption by 2-3 percentage points.
Long service life. Under normal circumstances, the service life of the activated calcium oxide rotary kiln production line with a daily output of 800-1000 tons can reach more than 18 months.
High-quality refractory brick products cannot be separated from the strong technical support of powerful refractory material manufacturers. Rongsheng refractory material manufacturer, with a large plant scale and a wide range of refractory products, can provide customized high-quality refractory lining material solutions for high-temperature industrial furnaces. Contact Rongsheng for more information.
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