The main component of bauxite is alumina, which is hydrated alumina containing impurities and is an earthy mineral. White or off-white, brownish yellow or light red due to iron. Density 3.9 ~ 4g/cm3, hardness 1 ~ 3, opaque, brittle. Extremely difficult to melt. Insoluble in water, soluble in sulfuric acid and sodium hydroxide solution.

The bauxite referred to in the refractory industry generally with calcined Al2O3 greater than or equal to 48% and low Fe2O3. The clinker is grayish white, light yellow and dark gray. It is mainly used for high aluminum refractory materials and can also be used to make fused brown corundum.

It is typically calssified according to its intended commercial application, such as abrasive ,cement, chemical, metallurgical, and refractory. as raw material for use in high alumina and super duty refractory bricks and shapes ,plastics, castable refractory, motors, gun mixes, ramming mixes, abrasive grains and other products.

China's bauxite resources are relatively abundant. In 18 provinces, autonomous regions, and municipalities directly under the Central Government, 205 producing areas have been identified, including 72 large-scale producing areas (excluding Taiwan). Mainly distributed in Shanxi, Shandong, Hebei, Henan, Guizhou, Sichuan, Guangxi, Liaoning, Hunan and other places.

As an additive material for sintered flux, ore from Henan is mainly used. The ore veins are mainly distributed in Luoyang, Zhengzhou and other places. Compared with Shanxi materials, the density is lower. It produced in Shanxi is more used in refractory materials.

After calcined, its physical and chemical properties change as follows:

1. The appearance changes from the original gray, dark gray, gray-yellow, gray-white, red-yellow and other colors to white, beige, brown-red, and blue, and blue deepens as the aluminum content increases. The original earthy luster becomes corundum luster or grease luster, and sometimes slightly molten stones or cracks appear on the surface;

2. The alumina content increases by 11 to 13%, and other impurities increase slightly;

3. The volume is reduced by about 23%;

4. Loss on ignition is about 14.5%;

5. Change from monohydrate type alumina or monohydrate-kaolinite type to artificial corundum, mullite and a small amount of glass phase;

6. The hardness is increased from 1 to 3 to 8 or more;

7. The bulk density is increased from about 2.5g/cm3 to over 2.8～3g/cm3;

8. Crystal water, structural water, and attached water all overflow;

9. The structure changes from loose, loose and soft to dense and hard;

10. Reduced water absorption; enhanced slag resistance and alkali resistance;

12. Increased strength;

13. Reduced permeability;

14. The gasification rate is reduced;

15. Volatile components, flammable components, soil odor completely disappeared;

16. The refractoriness reaches above 1780℃.

Application:

1. Precision casting. It is processed into fine powder to make a mold and then cast.

2. Aluminum smelting industry. Used in national defense, aviation, automobile, electrical appliances, chemical industry, daily necessities.

3. Used for refractory products. It has a fire resistance of up to 1780 ° C, strong chemical stability and good physical properties.

4. Aluminum silicate refractory fiber. It has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small heat capacity and resistance to mechanical vibration. Used in various industries such as steel, nonferrous metallurgy, electronics, petroleum, chemical industry, aerospace, atomic energy, national defense, etc.

5. Using magnesia and it clinker as raw materials, adding appropriate binders, it is used for pouring steel drums and the overall barrel lining effect is very good.

6. Manufacture of alumina cement, abrasive materials, various compounds that can be made of aluminum in the ceramic industry and chemical industry .

Physical And Chemical Indicators