Method for preparing metal aluminum through microwave chlorination of coal ash

Abstract

Disclosed is a method for preparing metal aluminum through microwave chlorination of coal ash. The method specifically comprises the following steps that carbon is added into the high-aluminum coal ash, the carbon and the coal ash are mixed evenly, and chlorine is led in; heating is conducted for 5-60 min through a microwave fluidized bed to 300-1200 DEG C, and constant temperature is kept for 10-60 min; the high-aluminum coal ash is fully decomposed, and various chlorinated mixed gases containing aluminum chloride are obtained; then through purification and rectification, aluminum chloride anhydrous with the purity being 99% or above is obtained; a sodium hydroxide solution is added to the aluminum chloride anhydrous to obtain an intermediate product, and through precipitation, filtration and solid-liquid separation, aluminum hydroxide precipitates and a sodium chloride solution are obtained; aluminum hydroxide is precipitated, calcination is conducted at the temperature of 800-1200 DEG C, and aluminum oxide is generated through decomposition; and the aluminum oxide is electrolyzed to obtain the metal aluminum. According to the method, the technological process is simple, and a clean technology with low energy consumption is achieved. Chlorine and sodium hydroxide generated by a system are both recycled, and effective full element separation utilization can also be achieved. No discharging of waste water or waste acid or waste alkali liquor occurs in the system, and zero discharging of three wastes is achieved basically.

Description

technical field [0001] The invention belongs to the technical field of aluminum production, in particular to a method for preparing metallic aluminum by microwave chlorination of fly ash. Background technique [0002] Fly ash is a solid waste after coal combustion. The alumina content in fly ash is equivalent to that in my country's medium and low-grade bauxite. High-alumina fly ash is a substitute for bauxite in my country's alumina industry. potential resources. Fly ash is the main source of suspended particulate matter, causing regional air pollution and endangering human health. Long-term stockpiling of fly ash will also pollute soil and water bodies, threatening human health and wasting a lot of water resources. Technically, the application research of fly ash is basically divided into three levels: low, medium and high: the low level refers to the use in road and dam construction, etc.; the middle level refers to the use as building materials; the high level refers to...

AI Technical Summary

Problems solved by technology

Such as patents CN1923695A, CN1920067A, CN101045543A, CN101397146A, etc., but in the production process, the method of acid dissolution first and then alkali dissolution complicates the production process and increases the production cost

[0007] There are many shortcomings in the existing technology of producing alumina from fly ash: the raw material cost of limestone sintering is low

However, the disadvantage of the acid method is that it is difficult to remove impurities during the acid dissolution process.

Moreover, the production process is complicated, the equipment requirements are high, and the production cost is high.

Images