Chair of Non-Ferrous Metals and Gold, National University of Science and Technology “MISiS”, Moscow, Russia:

A. S. Medvedev, Professor, e-mail: medvedev@splav.dol.ru
P. V. Aleksandrov, Senior Lecturer
V. A. Imideev, Post-Graduate Student

The prospectiveness of low-temperature roasting of sulphide nickel raw materials with alkaline metal chlorides is caused by reduction of SO₂ discharge into the air and formation of watersoluble nickel compounds during roasting. NiCl₂, NiSO₄ and NiO were defined as thermodynamic feasible products of reaction between nickel sulphide and sodium chloride in the presence of oxygen. Solid products of interaction of nickel sulphide concentrate with sodium chloride in the presence of oxygen were experimentally established by X-ray diffraction analysis. There was experimentally determined, that in case of roasting of nickel sulphide concentrate without NaCl in the temperature of 450 ^oС, nickel is mostly included in residue in sulphide form. In case of roasting with sodium chloride, nickel sulphide wasn’t found in residue. Unfortunately, water-soluble compounds of molybdenum in residue weren’t identified by X-ray diffraction analysis (neither sulphate no chloride), which probably reason is amorphous form of water-soluble compounds. Mixture of concentrate and sodium chloride was roasted in the temperature range of 300–600 ^oС with further leaching of solid residue by water and sulphuric acid in order to determine the optimal temperature of roasting with NaCl. Best results were achieved by roasting of nickel sulphide concentrate with sodium chloride in the temperature range of 350–400 ^oС. Under these conditions, it is possible to recover 85% of Ni and 96% of Ni by water and acid leaching, respectively. In order to decrease the sulphuric acid consumption, it is reasonable to arrange water and acid leaching process stages.

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