A. A. Baikov Institute of Metallurgy and Material Science, Russian Academy of Sciences, Moscow, Russia:

K. G. Anisonyan, Senior Researcher, e-mail: grikar84@mail.ru
D. Yu. Kopyev, Researcher
T. V. Olyunina, Senior Researcher
G. B. Sadykhov, Head of Laboratory, Chief Researcher

Red mud is an alumina production waste. Due to the absence of effective recycling technologies, red mud is practically not used and is stored in special sludge deposits, representing a serious technogenic threat for the environment and neighboring settlements. Tens of millions tons of red mud are sent to the dumps every year. 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 iron- and aluminium-containing products. The present paper contains the results of the investigations focused on developing a single-stage reducing roasting process with simultaneous production of cast iron and aluminate slag, the main aluminium-containing component of which is a water-soluble sodium aluminate. Forming of reguired slag composition is achieved by adding Na₂CO₃ and CaCO₃ to a furnace charge in definite proportions. It was studied the influence of these additions on degree of aluminium extraction into solution during the aluminate slag leaching in an alkalescent aqueous medium. It has been determined that adding of 15% Na₂CO₃ and 20% CaCO₃ provides the most complete aluminium extraction into solution during leaching the product of the red mud reducing roasting. At the same time, an incomplete aluminium extraction is associated with formation in the system of complex calcium aluminosilicates (helenite predominantly). The carried out study has showed a principle possibility of aluminate slag obtaining in the process of a red mud single-stage reducing roasting and subsequent aluminium extraction into solution by water leaching in an alkalescent aqueous medium.

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

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