Method for preparing alpha-aluminum oxide

Abstract

The invention discloses a method for preparing an alpha-aluminum oxide, and relates to a method for preparing a low-sodium alpha-aluminum oxide which is used for producing electronic ceramics, glass substrates and finely polished and refractory materials. The method is characterized by comprising the following preparation processes: by adopting an industrial aluminum oxide as a raw material, carrying out hydrothermal reaction on industrial aluminum oxide slurry, carrying out liquid-solid separation and washing the slurry; and finally calcining to obtain a low-sodium alpha-aluminum oxide product. According to the method disclosed by the invention, soluble impurities such as sodium oxide and potassium oxide in the aluminum oxide raw material can be effectively removed; a crystal shape modifier is added in the wet treatment process; a trace crystal shape modifier can be fully mixed with the aluminum oxide by virtue of the adsorptive property of the aluminum oxide; the aluminum oxide of which the sodium oxide content is smaller than 0.15% is obtained after filtering and washing; and the low-sodium alpha-aluminum oxide product is obtained in a calcining manner in a high-temperature kiln. The method disclosed by the invention has the advantages of being simple in process, environment-friendly, high in production efficiency and the like, and the alpha-aluminum oxide is uniform in crystal particle.

Description

technical field [0001] The invention relates to a preparation method of α-alumina, which relates to a preparation method of low-sodium α-alumina used in the production of electronic ceramics, glass substrates, fine polishing and refractory materials. Background technique [0002] Low-sodium α-alumina has the advantages of wear resistance, corrosion resistance, and good insulation. It is used in the production of functional ceramics, precision ceramics, integrated circuit chips, aviation light source devices, electronic ceramics, semiconductor substrates, etc., as well as hard disk substrates and sapphire substrates for LEDs. It has been widely used in the fine polishing of chips. [0003] At present, many domestic enterprises use metallurgical grade alumina or aluminum hydroxide as raw materials to produce low-sodium alumina by adding a large amount of mineralizers such as boric acid, ammonium fluoride, and ammonium chloride through high-temperature desalination. Due to the...

AI Technical Summary

Problems solved by technology

Ma Shuyun and others used high-quality industrial alumina as the main raw material, added pseudo-boehmite, ammonium chloride, aluminum fluoride, and barium fluoride as auxiliary raw materials. After grinding and mixing the above raw materials, they were calcined at high temperature in a tunnel kiln, and then Low-sodium fine-grained α-alumina for electronic ceramics is obtained after dry ball milling, stirring milling, and drying. The process is long, the energy consumption is high, and the product performance is poor.

Pan Xiaobing et al. used boehmite as raw material, and used organic acid to wash and remove impurities for boehmite several times, and then spray-dried the purified boehmite filter cake to obtain boehmite powder, which was then calcined at high temperature to obtain boehmite powder suitable for electronic products. Ultra-fine low-sodium α-alumina for ceramic production has problems such as high raw material cost and high energy consumption

There are also many open methods for producing low-sodium alumina, but due to the high price of raw materials and complicated processes, the production cost is too high, and it is difficult to achieve economical scale production.

Moreover, the production of low-sodium alumina by Sui Dao kiln needs to put the materials into the sagger, which is labor-intensive, low in production efficiency and high in energy consumption.

The invention patent [CN 103332718] of Li Junhu et al. uses industrial aluminum hydroxide as raw material to reduce the alkali content in aluminum hydroxide by acid-eluting sodium hydroxide in a strong acidic solution, and then through adding chloride crystal habit during the calcination process The regulator is calcined at high temperature to prepare low-sodium fine-grained alumina. However, since the sodium oxide in aluminum hydroxide exists in three forms: adsorbed alkali, intergranular alkali and bound alkali, wet washing can only wash away the adsorbed alkali. , so the sodium oxide impurity content in the washed aluminum hydroxide is still high, and it is still necessary to prepare low-sodium alumina by adding a large amount of mineralizer and then calcining at high temperature

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