Method for preparing metal aluminum from bauxite through microwave chlorination

Abstract

A method for preparing metal aluminum from bauxite through microwave chlorination specifically includes the following steps that carbon is added in the bauxite to be evenly mixed, chlorine is pumped in, heating is conducted through a microwave fluidized bed for 5 min to 50 min, the temperature ranging from 300 DEG C to 900 DEG C is achieved, the temperature keeps constant for 10 min to 60 min, the bauxite is sufficiently decomposed, various types of chlorination mixed gas containing aluminum chloride is obtained, and then anhydrous aluminum chloride with the purity larger than 99% is prepared through impurity removal and purification; a sodium hydroxide solution is added in the anhydrous aluminum chloride, an intermediate product is prepared, and aluminum hydroxide precipitate and a sodium chloride solution are obtained through precipitation, filtration and solid-liquid separation; the aluminum hydroxide precipitate is calcined at a temperature ranging from 800 DEG C to 1200 DEG C and decomposed to generate aluminum oxide; and the aluminum oxide is subjected to electrolysis to obtain the metal aluminum. The method is a clean process which is simple in technological process and low in energy consumption, all chlorine gas and sodium hydroxide which are generated by the system are used in a cyclic manner, all elements can be effectively separated and utilized, the whole system is free of emission of waste water, waste acid and waste alkali liquid, and zero emission of 'three wastes' is basically achieved.

Description

technical field [0001] The invention belongs to the technical field of aluminum production, in particular to a method for preparing metal aluminum by microwave chlorination of bauxite. Background technique [0002] my country's bauxite resources are relatively rich. As of 2006, the reserved resource reserves were 2.776 billion tons, including 542 million tons of reserves, 742 million tons of basic reserves, and 235 million tons of resources, and the distribution is relatively concentrated. The type of bauxite in my country is mainly kaolinite-diaspore type, accounting for more than 98% of the total reserves, while the gibbsite type bauxite is only found in Hainan, Guangdong, Fujian, Taiwan and other provinces. distribution, the reserves are less than 2%. The average grade of each component of bauxite in my country is: Al 2 o 3 61.69%, SiO 2 10.4%, Fe 2 o 3 7.73%, belonging to high aluminum, high silicon, low iron refractory ore, the average aluminum silicon ratio of the...

AI Technical Summary

Problems solved by technology

The problem of the Bayer-sintering joint process for producing alumina is that: there are two processes of Bayer process and sintering process at the same time, the production process is complicated, and there are many equipments; the two sets of processes intersect each other, and the production coordination is very complicated

However, in this method, a common fluidized bed is used as the reaction device, which requires high equipment, high energy consumption, and high production costs.

[0010] In the process of producing alumina by the Bayer process using diaspore, lime is usually used as an additive. In the process of producing alumina by the Bayer process using diaspore as a raw material, adding lime can play the following roles: large Significantly reduce the N / S of the dissolved red mud, so that the middle and low-grade diaspore bauxite is suitable for Bayer process; slow down the formation speed and degree of scarring during the dissolution process; increase the overall dissolution rate; increase the Al 2 o 3 However, the addition of lime in the production of alumina by the Bayer method still has the following defects: the A / S in the red mud dissolved by the Bayer method after adding lime is higher than that of the red mud dissolved by the conventional Bayer method. Under the same dissolution conditions, the aluminum ore The unit consumption increases, although the increase of lime helps to reduce the alkali consumption, but it reduces the comprehensive utilization efficiency of ore; the consumption of lime increases, so the consumption of limestone and coke also increases

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