ALUMINIUM PRODUCTION SLUDGE DISPOSAL METHOD Russian patent published in 2017 - IPC C22B7/00 

FIELD: metallurgy.

SUBSTANCE: method involves sludge washing from sodium sulfate, thickening, filtering and drying, removing carbon during oxidative roasting in the reactor at a temperature of 780-800°C, electrolysis of the obtained materials in the electrolytic bath and casting of aluminium into moulds at a temperature not lower than 820°C, while washing the sludge from sodium sulfate, sludge drying and oxidizing roasting, water and air are used, heated by the heat of the flue gases leaving the reactor. From every 20 kg of total dust emissions of electrostatic precipitators and gas cleaning sludge per ton of raw aluminium, ~6.4 kg of fluorosols (cryolite) and about 3.3 kg of aluminium with a high iron content are obtained.

EFFECT: reduction in the volume of existing sludge fields and current recycling of gas cleaning waste of aluminium production to obtain secondary cryolite and aluminium having an iron content of up to 8 percent and silicon not more than 1,5 percent.

2 cl, 3 tbl