Basic information of alumina
Alumina is an inorganic substance with a chemical formula of Al₂O₃. It is a high-hardness compound with a melting point of 2054°C and a boiling point of 2980°C. It is an ionic crystal that can be ionized at high temperatures and is often used in the manufacture of refractory materials. Alumina is a stable oxide of aluminum and is also called bauxite in mining, ceramics, and materials science.
Properties: White solid insoluble in water, odorless, tasteless, extremely hard, easy to absorb moisture but not deliquescent (non-hygroscopic after burning). Alumina is a typical amphoteric oxide (corundum is alpha-shaped and belongs to the hexagonal densest packing, is an inert compound, slightly soluble in acid and alkali, corrosion resistance), soluble in inorganic acids and alkaline solutions, almost insoluble in water and non-polar Organic solvents; relative density (d204) 4.0.
Storage: sealed and dry storage.

 
Chemical properties
Reacts with acid:
Al₂O₃ + 6HCl = 2AlCl₃ + 3H₂O
Al₂O₃ + 6H⁺ = 2Al³⁺ + 3H₂O
React with molten alkali:
Al₂O₃ + 2NaOH= 2NaAlO₂(sodium metaaluminate)+ H₂O
React with alkali solution:
Al₂O₃+ 2NaOH +3H₂O = 2Na[Al(OH)₄](sodium tetrahydroxy aluminate)
It can also be abbreviated as: Al₂O₃+2OH^-=2AlO2^-(metaluminate ion)+H₂O
 
Alumina variants
There are many variants of Al₂O₃, the common ones are α and γ types are white crystals.
Corundum in nature is alpha type, which is the most densely packed hexagonal, with a melting point, high hardness, insoluble in acid and alkali, corrosion resistance, and good insulation.
Co-heating aluminum hydroxide and partial aluminum hydroxide or aluminum ammonium alum at 723K can obtain γ-type, which is insoluble in water, but has strong water absorption, strong adsorption capacity and catalytic activity.
The beta form has ion conductivity and allows Na⁺ to pass through.
 
The development of alumina
Data show that China is the world's largest alumina producer. In 2010, global alumina production was 56.355 million tons, and China's alumina production reached 28.955,000 tons, an increase of 20.14% year-on-year, accounting for 51.38% of the world's total. In 2010, China’s apparent alumina consumption reached 33.21 million tons, with an annual growth rate of 14.05%, net imports of 4.26 million tons, and bauxite imports of 30.19 million tons, with 39.71% of external dependence and 39.71% of external dependence on alumina. Up to 47.26%.
With the rapid development of my country's electrolytic aluminum, ceramics, medicine, electronics, machinery, and other industries, the market still has a large room for growth in demand for alumina, and alumina output will continue to grow. Combining China’s alumina production data from 2005 to 2010, it is estimated that China’s alumina production will reach 33 million tons in 2011, with a growth rate of 14%. In 2012, it will continue to grow on the basis of 2011, and the output will exceed 38 million tons.
In addition, given that China's construction area under construction continues to grow substantially year-on-year, and due to the continuous implementation of urbanization, the future prospects of the aluminum industry are very optimistic. It is estimated that in 2011, China's alumina demand will increase by 15% year-on-year to 38.19 million tons. In 2012, alumina demand will reach 42 million tons, an increase of 10% year on year.
 
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