Use of thermochemistry methods when processing oxidized nickel ores

Abstract

About 60–70% of the surface reserves of nickel are concentrated in oxidized (laterite) ores. Approximately 40% of nickel is produced from this type of raw material. Due to the depletion of nickel sulfide ores and the growing demand for metal, interest in the processing of oxidized ores is growing, despite the low content of a valuable component (0,75–1%) and some difficulties of processing them. Currently in non-ferrous metallurgy various pyrometallurgical, hydrometallurgical or combined pyro-hydrometallurgical methods of processing of oxidized nickel ores with obtaining metallic nickel and cobalt or their compounds are employed. Significant reserves of oxidized nickel ores are located in the Urals: in the Chelyabinsk, Sverdlovsk and Orenburg regions. Reducing-sulphidizing smelting of laterite ore to produce fire nickel, which has been used at Ural enterprises for many years, is not profitable in the current economic conditions. The widespread of hydrometallurgical technologies is hindered by the high cost of reagents and the unsatisfactory extraction of valuable components from ores. One of the options for improving such technologies may be the use of thermochemical methods, as preparatory stage for opening resistant nickel-containing minerals. The paper presents the results of studies of high-temperature sulfatization of the Ural oxidized ores. The choice of reagent is due to the availability and low price of sulfuric acid. It was shown that at an acid consumption of 0,7 g per 1 g of ore and at a sulfatization temperature of 420 oC, the maximum nickel recovery in solution is 80–82%. The hard filterability of the obtained pulps determines the feasibility of considering such technological methods for the extraction of Ni and Co, as sorption leaching. The use of sorption extraction of nickel from leaching solutions is possible after their preliminary purification from iron. Promising are chelating selective ion exchangers.