Method for efficiently deironing coal ash

Abstract

The invention provides a method for efficiently deironing coal ash. Fine powder of raw coal ash is sequentially subjected to reduction, magnetic separation and hydrochloric acid leaching treatment, thereby finally obtaining the coal ash with the Fe2O3 content less than 0.02%. The method has the beneficial effects that the technology operation is simple, and the deironing efficiency is high, so that the Fe2O3 content in the coal ash is reduced to be lower than 0.02%; the calcium impurity also can be removed; moreover, a molecular sieve prepared by utilizing the coal ash after deironing by the method is high in quality, and the Fe2O3 content is less than the commercial value; not only can a duct of the molecular sieve be prevented from being blocked by a ferrum ion, but also the adsorption-desorption circulation service life can be prolonged. In addition, with the method, iron powder can be recycled in the magnetic separation process for iron smelting.

Description

technical field [0001] The invention relates to a method for reducing and efficiently removing iron from fly ash. Background technique [0002] Fly ash is a fine-grained dispersed residue after coal or coal powder combustion, and it is one of the industrial wastes with a large discharge volume in my country. In 1995, my country's fly ash discharge amounted to 125 million tons, in 2000 it was about 150 million tons, and in 2010 it reached 300 million tons. According to experts' prediction, my country's fly ash discharge will reach 570 million tons in 2015. A large amount of fly ash If it is not treated, it will generate dust and pollute the atmosphere. If it is discharged into the water system, it will cause river silting, and the toxic and harmful chemicals in it will also cause harm to humans and organisms. The comprehensive utilization of fly ash to turn waste into treasure has become an important technical and economic policy in my country's economic construction, and it ...

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Problems solved by technology

Inventions CN10272561B and CN201848307U adopt magnetic separation to remove iron, but since the iron in fly ash is mainly ferric iron, and ferric iron is weakly magnetic, the effect is poor; patent CN103131860A uses alkali to calcinate to activate fly ash and then add mixed acid Leaching to remove iron, this method consumes a lot of acid and alkali, and cannot remove all the iron in fly ash; Master's thesis of Northeast Petroleum University in 2014——Preparation of ZSM-5 molecular sieve by two-step method using fly ash raw materials The research also reported that only relying on the acid leaching method can not remove all the iron in the fly ash; the patent CN103833061A adopts a combined method to remove iron from the fly ash leachate, this method can remove the iron ions in the solution, but the solid phase The iron in it has little effect

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