Method for extracting metal from coal ash by fused salt electrolysis method

Abstract

The invention discloses a method for extracting metal from coal ash by a fused salt electrolysis method, which belongs to the technical field of metallurgy. The method I comprises the following steps: (1) mixing Na3AlF6 and AlF3 to prepare cryolite-based fused salt; (2) putting the cryolite-based fused salt into an electrolytic bath, and adding the coal ash; and (3) heating the electrolytic bath to 910-985 DEG C, then electrifying for electrolysis, depositing on a negative pole to form an aluminium-based alloy. The method II comprises the following steps: (1) mixing Na3AlF6 and AlF3 uniformly to prepare cryolite-based fused salt; (2) putting the cryolite-based fused salt into an electrolytic bath, and adding the coal ash and aluminium oxide; and (3) heating the electrolytic bath to 930-985 DEG C, then electrifying for electrolysis, and after the electrolysis is finished, depositing on a negative pole to form an aluminium-based alloy. The method disclosed by the invention has the beneficial effects that the coal ash is treated by the fused salt electrolysis method, oxides of aluminium, silicon, titanium, iron and the like are directly electrodeposited to prepare the alloy, so that the green, high-efficiency and comprehensive utilization of the coal ash is realized. The method disclosed by the invention has the advantages that the process is simple, the production can be carried out in an existing industrial aluminium electrolysis bath, the flow process is short and continuous production can be achieved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a method for extracting metal from fly ash by molten salt electrolysis. Background technique [0002] Fly ash, commonly known as fly ash, refers to the dust and bottom slag collected from the flue gas of coal-fired (including gangue and coal slime) boilers, as well as the desulfurization and denitrification ash produced in the production process of coal-fired power plants. The output and discharge of fly ash are increasing year by year, and the accumulation of fly ash has obviously become a public hazard. The chemical composition of fly ash mainly includes silicon oxide, aluminum oxide, iron oxide, calcium oxide, magnesium oxide, potassium oxide, sodium oxide, sulfur trioxide, loss on ignition, etc. [0003] At present, the utilization of fly ash is mainly concentrated in building materials and road construction projects, etc., which basically belongs to the extensive utiliza...

AI Technical Summary

Problems solved by technology

Among them, the alkali method mainly includes soda lime sintering method and limestone sintering method. The alkali reactant of the alkali method process cannot be recycled, the energy consumption is high, the production cost is high, and the amount of residue generated is large; the acid leaching method mainly adopts sulfuric acid or hydrochloric acid leaching Fly ash, Fe, K, Mg, Ca and other elements can also be leached during acid leaching, which increases the difficulty of alumina extraction, and the equipment is severely corroded and the production cost is high; the quality of the alumina product produced by the acid-base method Higher, but there are many production processes and equipment, large energy consumption, and high production costs; the ammonium sulfate roasting method uses fly ash and ammonium sulfate to mix and roast, but there are still problems such as high energy consumption and low purification rate

In these research works, only the recycling of aluminum resources is reflected, and the comprehensive utilization of silica and alumina in fly ash has not yet been truly reflected.

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