Alumina, chemical formula Al? o？ High hardness compound, melting point 2054℃, boiling point 2980℃. It is an ionic crystal that can ionize at high temperature and is often used to make refractories.
For Al. o？ There are many variants, the common ones are α and γ, which are white crystals. In nature, corundum is α-shaped, belonging to the densest packing of hexagons, with high melting point, high hardness, insoluble in acid and alkali, corrosion resistance and good insulation. When aluminum hydroxide is mixed with aluminum hydroxide or aluminum ammonium alum at 723K***, γ-shape can be obtained, which is insoluble in water, but has strong water absorption and adsorption capacity and catalytic activity. The β-shape has ionic conductivity and allows Na+ to pass through.
Sodium hydroxide, with the chemical formula of NaOH, commonly known as caustic soda, caustic soda and caustic soda, is a strongly corrosive alkali, generally in the form of flake or block, which is easily soluble in water (exothermic when dissolved in water) and forms an alkaline solution, otherwise it is easy to deliquesce and absorb water vapor (deliquescence) and carbon dioxide (deterioration) in the air. Hydrochloric acid can be added to check for deterioration.
Alumina use
According to different uses, alumina can be divided into metallurgical grade alumina and non-metallurgical grade alumina. There is no difference between the two production processes, but the purity of non-metallurgical grade alumina is generally higher than that of metallurgical grade alumina. Metallurgical grade alumina is mainly used to produce electrolytic aluminum, while non-metallurgical grade alumina is mainly used to produce alumina products such as corundum, ceramics and refractory products.
The output of metallurgical grade alumina accounts for about 95-97% of the total output of alumina. The subject matter of the alumina futures contract listed in the last issue is metallurgical grade alumina.