METHOD FOR PROCESSING GAS CLEANING SLIME IN PRODUCTION OF PRIMARY ALUMINUM Russian patent published in 1997 - IPC

FIELD: processing the waste of gas cleaning in aluminum production. SUBSTANCE: method includes subjection of slime to magnetic separation with magnetic field intensity of at least 1000 Oe, and then to high-temperature oxidizing roasting with introduction of modifying additive and subsequent desulfurizing of return product with water. Modifying additive is used in the form of lithium compound in the amount of 7.5-10.0 mas.% in terms of Li₂O, or sodium compound in the amount of 10.0-15.0 mas.% in terms of Na₂O. The invention makes it possible not only to reduce fluorine losses and content of impurities in the form of iron and sulfur in return product in processing wastes of primary aluminum production, but also to increase technical-and-economic indices of roasting process because this process is conducted at lower temperatures (500-600 C). EFFECT: provision of producing secondary raw materials from slimes of gas treatment system in aluminum production with use of self-baking anodes and reduced losses of fluorine in production of return product. 4 cl, 2 tbl