Establishment of Russian Academy of Sciences I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials of the Kola Science Centre of Russian Academy of Sciences

V. A. Matveev, Senior Researcher
V. I. Zakharov, Head of Laboratory
D. V. Mayorov, Senior Researcher; e-mail: mayorov@chemy.kolasc.net.ru

Today, about 40% of produced in country alumina has been obtained from Kola nepheline and nepheline syenites from Siberian deposits, using method of baking with limestone. Analysis of existent position has been testified about actuality of creation of new high-efficiency technologies of nepheline processing, especially technologies, which have been immediately realized at Kola Peninsula. It has been demonstrated that, in principle, nepheline can be processed with nitric acid by the pattern involving incomplete decomposition of aluminium nitrate at 250–270 ^oC. This allows to streamline the equipment for thermal decomposition and nitric acid recovery, to upgrade the process of aluminium hydroxide separation from saltpeter solution, and reduce the power and material flows. About 380–390 kg of rough aluminium hydroxide (64–66% Al₂O₃) and 700–720 kg of mixture, included ammonical, sodium and potassium nitres can be obtained during processing of 1000 kg of nepheline concentrate by presented technology. Rough hydroxide can be refined by simplified Bayer scheme or can be processing to coagulating agent, used during water clearing. Salts add output is about 3 tonnes on 1 tonne of productional alumina.

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