SU1399374A1 - Method of processing fluorine-containing waste of aluminium production - Google Patents

Description

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The invention relates to non-ferrous metallurgy and can be used in the production of aluminum by electrolysis.

The purpose of the invention is to increase the efficiency of the process by increasing the yield of fluorine in the product, reducing the consumption of soda and increasing the degree of purification from sulphates.

Example. Exhaust gases from aluminum electrolysis cells are fed to pick up pypi. After the supply, gases containing HF, CO and solid particles are fed to the purification, where they are treated with 2000 m of soda solution containing, g / l: NaF 4.1; 25; NaHCOj 5; Na2S04 50.6. You get a 1600 m solution with a content, g / l: NaF 15,1; 9; NaHCO, 23; 70

After separation of the sludge, the amount of the solution is 15bO.

Then the coal foam is floated with the flotation tailings separated. Cryolite in an amount of 15.9 tons is precipitated from sodium aluminate solution. The mother liquor containing 5 g / l of NaF; Na SO 70 g / l, sodium carbonate and bicarbonate are divided into 2 parts, 1140 m is sent for the preparation of soda solution, 426 m together with wastewater (from washing sediments, flotation, equipment washing, water wash) in the amount of 506 m. provide for the treatment of gas and dust gas cleaning and flotation tailings. Wastewater contains NaF 1.2 g / l and 1.5 g / l. The mixture of the mother liquor with wastewater has the following composition, g / l: NaF 2.9; 34. 6 tons of gas cleaning sludge, 21 tons of electrostatic precipitators, and 20.7 tons of flotation tailings were put into processing. The ratio of drills and drums to the tails of flotation is 1 1 1S 3 Обработ Processing is carried out at a temperature below zero. Crystals of sodium sulfate decahydrate NajSO x lOH / jO fall out of solution together with solid particles as an insoluble monolithic precipitate. The amount of sodium sulfate released is 8988.

The clarified purified water in the amount of 860 m, containing NaF 2.9 g / l (.-2.5 g / l, soda and bicarbonate.

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sent to the preparation of soda solution. The return of water makes it possible to return to production 10.5 g of products and 2.5 g of fluorine and to obtain an additional 4.6 kg of cryolite.

This ratio of dust and gas cleaning sludge to flotation tails is due to the fact that with an increase in the proportion of flotation tailings, the precipitate increases and the degree of sodium sulfate transition into solution. With the dust ratio of electrostatic precipitators and pshams to flotation tails less than 0.5, the rate of clarification of the solutions decreases.

The proposed method allows to increase the yield of fluorine, reduce soda consumption, and increase the degree of purification of sulphate solutions.

Claims (1)

Invention Formula A method for processing fluorine-containing aluminum production wastes, including capturing dusters from exhaust gases of aluminum electrolyzers, preparing soda solution, purifying gases with soda solution — separating gas cleaning sludge from the resulting solution, flotation of coal foam with separation of flotation tailings, processing the solution after gas cleaning with sodium aluminate, separating formed cryolite from the mother liquor, treatment of the mother liquor with gas purifiers and gas flotation tailings, separation of solid particles from the mixture and the supply of the clarified solution to the preparation of soda solution, characterized in that, in order to increase the efficiency of the process by increasing the yield of fluorine in the product, reducing the consumption of soda and increasing the degree of purification from sulfates, part of the mother liquor is fed to the preparation of soda solution after separation cryolite, treatment of the mother liquor with gas cleaning slimes and flotation tailings is carried out with the addition of the process wastewater and dredging from the stage of its trapping at a mass ratio of dredge and sludge in the gas cleaning mixture to the flotation tails of 1: 0.5-2.0 and at a temperature below. VNIIPI Order 2648/30 Circulation 621 Prod-polygr. pr-tie, Uzhgorod, st. Project, 4 Pods