METHOD OF PROCESSING OF SODIUM-FLUORINE-CARBON-CONTAINING WASTE OF ELECTROLYTIC PRODUCTION OF ALUMINIUM Russian patent published in 2017 - IPC C22B7/00 C01F11/22 

FIELD: chemistry.

SUBSTANCE: process involves the treatment of sodium-fluorine-carbon-containing electrolytic aluminium waste with a lime-containing reagent at elevated temperature with stirring and a weight ratio of the amount of fluorine in the waste to the amount of active calcium oxide in the lime-containing reagent of 1:(1.40÷1.65), the treatment being carried out in a saline solution from a slurry field or in solution from an aluminium wet scrubbing system, the amount of lime-containing reagent fed to treat 1 ton of waste is further increased in proportion to the volume of saline supplied to the waste treatment and concentration in saline solution NaF, Na₂CO₃, NaHCO₃: CaO_act=(1,00÷1,05)×[0,88×Q_sol×C_NaF+0,70×Q_sol×C_Na2CO3+0,44×Q_sol×C_NaHCO3], where: CaO_act - additional amount of active calcium oxide in lime-containing reagent for processing 1 ton of waste in saline solution, kg, Q_sol - amount of salt solution applied to the 1 ton of waste processing, m³, C_NaF, C_Na2CO3, C_NaHCO3 - correspondively to saline solution concentration NaF, Na₂CO₃, NaHCO₃, kg/m³, (1,00÷1,05) - coefficient of extra active calcium oxide-interval, which reach a maximum efficiency in the processing of sodium-fluoro-carbon-containing wastes of electrolytic aluminium production lime-containing reagent. The treatment of sodium-fluorine-carbon-containing wastes of electrolytic aluminium production with a lime-containing reagent is carried out with the addition of industrial water to the saline solution, the processing temperature is reduced to 40÷65°C, a solid lime-containing reagent is used which is loaded into a slurry of sodium-fluorine-carbonaceous wastes in saline solution, and the caustic soda solution obtained as a result of waste treatment with a lime-containing reagent is treated with gases containing carbon dioxide before being fed into the wet scrubbing system.

EFFECT: increasing the technical and economic parameters of the process due to the receipt of additional amounts of calcium fluoride and caustic soda solution, reduction of energy inputs and labour costs for processing sodium-fluorine-carbon-containing waste, and reduction of technical water consumption.

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