Process method for producing high-purity aluminum oxide and silicate by using pulverized fuel ash

Abstract

The invention discloses a process method for producing high-purity aluminum oxide and silicate by using pulverized fuel ash and belongs to the technical field of pulverized fuel ash resource utilization. Aluminum oxide and parts of silicon oxide in the pulverized fuel ash and uranium, thorium and other elements in radioactive pulverized fuel ash are recycled by means of the process method, accordingly the pulverized fuel ash resource utilization and remarkable reduction of solid wastes are achieved, quantity of tailings does not reach quarter of weight of original pulverized fuel ash, and the purity of the aluminum oxide and the silicate produced by means of the process method is high. The industrialization of the process flow of the process method is easily achieved.

Description

technical field [0001] The invention belongs to the technical field of fly ash resource utilization, and in particular relates to a process for producing high-purity alumina and silicate from fly ash. Background technique [0002] The main components of fly ash are aluminum oxide and silicon dioxide, which account for more than 85% of its weight, so it is a relatively large source of silicon and aluminum. In 2010, the annual production of fly ash in my country was about 500 million tons. Calculated at 30% content, the alumina content in the fly ash produced in my country in that year was about 150 million tons. In 2010, the total output of alumina in my country was only 29.94 million tons, and the total output of the world (including my country) was only 86.28 million tons. In addition, fly ash from certain sources contains high concentrations of iron oxide and scattered and scarce metal elements such as gallium and germanium. The fly ash produced by pit-mouth power plants ...

AI Technical Summary

Problems solved by technology

[0005] The disclosed methods all have their own advantages and disadvantages. For example, the limestone sintering method and the soda lime sintering method all have a substantial increase in the amount of solid waste. The limestone sintering method and the soda lime sintering method produce 1 ton of alumina (about 2.5 tons of pulverized coal is consumed). ash), producing 9 tons of waste residue, and the pre-desilication-soda lime sintering method produces 4 tons of waste residue; in addition, there are still disadvantages such as high roasting temperature and high energy consumption

Although other methods have the advantage of relatively less solid waste residue, they only target the aluminum in fly ash, and discharge other useful resources into the waste residue, resulting in a serious waste of resources

[0006] Since alumina exists in the phase of mullite in fly ash, and according to our own experimental results, treatment such as mechanical grinding cannot cause phase transformation of mullite, therefore, the acid method that has been disclosed, whether sulfuric acid or hydrochloric acid , the leaching rate of alumina may be lower

In addition, most of the disclosed acid methods use high temperature and high pressure, operating concentrated acid under such conditions will be very dangerous, and the requirements for containers are also very high

[0007] To sum up, the patented technologies for resource utilization of fly ash that have been disclosed now have their own shortcomings, such as high energy consumption, harsh operating conditions, complicated process, high comprehensive cost, and the treatment of tailings. And secondary pollution and other issues, in addition, are not applicable to radioactive fly ash containing uranium and thorium

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