A. A. Baikov Institute of Metallurgy and Material Science of the Russian Academy of Sciences, Federal State Budgetary Science Institution:

K. G. Anisonyan, Senior Researcher, e-mail: grikar84@mail.ru
D. Yu. Kopyev, Researcher
K. V. Goncharov, Researcher
G. B. Sadykhov, Chief Researcher

Red mud is a technogenic waste product, a result of alumina production. It is a fine-dispersed material containing up to 60% Fe₂O₃ and up to 20% Al₂O₃. For each ton of alumina produced of bauxites there is more than 1 ton of red mud. In the absence of effective recycling technologies, red mud is practically not used and is almost completely stored in special sludge deposits, which negatively affects the environment. Tens of millions of tons of red mud are sent to the dumps every year in the world. More than 100 million tons of red mud has been piled up in Russia. High content of iron and aluminium in red mud requires a processing which provides an effective separation of these components and obtaining original iron- and aluminium-bearing products. In this connection, the present paper is focused on developing a single-stage reducing roasting process with simultaneous generation of cast iron, a product for steel industry, and the aluminate slag suitable for alumina production. The main stage of the red mud complex processing technology under development is a single-stage reducing roasting process which results in the cast iron and aluminate slag obtaining; the latter is further treated by water leaching for aluminium precipitation from solution. The roast is carried out for the ferric oxides reduction to metal and simultaneous aluminium transfer to water-insoluble sodium aluminate, which is provided by adding Na₂CO₃ and CaCO₃ to a furnace charge in definite proportions. This article considers the manner in which the reducing roasting conditions (temperature, consumption of a reducing agent, composition of the furnace charge) influence over the ferric oxides reduction to metal and obtaining of the aluminate slag with a definite phase composition. As a result, the optimal conditions of the slag and cast iron formation are determined.

The study was performed by a grant of the Russian Science Foundation (project No. 17-73-10414).

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