A method for extracting metals from fly ash by molten salt electrolysis

Abstract

Molten salt electrolysis is a method of extracting metals from fly ash, which belongs to the field of metallurgical technology. Method one is: (1) Mix Na3AlF6 and AlF3 to make cryolite-based molten salt; (2) Place it in an electrolytic tank and add pulverized coal Ash; (3) Heating to 910~985℃, then energizing for electrolysis, and depositing on the cathode to form an aluminum-based alloy. The second method is: (1) Mix Na3AlF6 and AlF3 evenly to make cryolite-based molten salt; (2) Place it in an electrolytic tank and add fly ash and alumina; (3) Heat it to 930~985°C, and then turn on electricity. Electrolysis, after the electrolysis is completed, the aluminum-based alloy is deposited on the cathode. The present invention processes fly ash by molten salt electrolysis and directly electrodeposits oxides such as aluminum, silicon, titanium and iron to prepare alloys, thereby realizing green and efficient comprehensive utilization of fly ash. It has a simple process and can be used in existing industrial aluminum electrolytic cells. It has the advantages of short production process and continuous production.

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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