Refractories for calciners and refractories for aluminium smelting in a suspended alumina furnace

Alumina suspended furnace calciner

Alumina baking is the last process in the production of alumina, mainly drying the water attached to the alumina filter cake, crystal water, and part of the alumina into alumina. At present the main domestic aluminum oxide manufacturers of aluminum hydroxide baking has all or part of the introduction of fluidized roasting device. Although the three types of fluidized roaster, fluidized bed and suspension roaster use different refractories, they all use a large number of amorphous refractories (refractory plastic or refractory castable), accounting for 50%~70% of the refractories used. The unsteady refractories of fluidized flash roaster are all imported from Germany, and the refractories of circulating fluidized bed roaster are all produced in China.

Of alumina gas suspension calciner is used for roasting aluminium hydroxide dedicated equipment, its technology and automation level is very high, in the high temperature furnace roasting process of working temperature about 1200 ℃, under the condition of high speed, at the same time as the process of alumina material hardness, good liquidity, in the quality of alumina products have very strict requirements, lining materials of any impurities mixed with a direct impact on the performance of the product, so for refractory materials must meet the following conditions: high temperature resistance, wear resistance, high strength, good thermal stability, good integrity, strong sealing.

Aluminium refractory

In the world nonferrous metal production, the annual output of aluminum ranks the first, far more than other nonferrous metals. The aluminium industry consumes far more refractories each year than copper, lead and zinc smelting combined. The production method of metallic aluminum is a fixed two-step process: the first step is to prepare alumina from bauxite ore by wet process; The second step is to take industrial alumina as raw material and make aluminium by molten salt electrolysis. The high temperature kilns used in the production process include rotary kiln, melting salt electrolytic cell, melting aluminum furnace and so on.

Aluminium industrial furnaces have a high consumption of refractories. The reason lies in that the alkaline substance in the material corrodes the refractory of rotary kiln seriously when making Al2O3. In the process of aluminum smelting, even at a low temperature, the metal aluminum still has a strong permeability. Once it penetrates into the brick, it reacts with SiO2 in the brick and reduces Si, which destroys the structure of refractory materials and causes the furnace lining to produce metamorphism layer, loose, spalling and damage. Its reaction: 3SiO2+4Al-- 2Al2O3+3Si.

Therefore, refractory materials containing SiO2 should not be used as furnace materials for metal aluminum smelting equipment. So general aluminum industrial furnace refractory, in addition to high - aluminum brick, commonly used carbon products.