Kola MMC JSC, Monchegorsk, Russia:

V. V. Kopylov, Head of the Engineering Center
K. V. Nesterov, Deputy General Director Responsible for Mining, Concentration and Smelting
E. A. Kurbatov, Chief Process Engineer at the Department of Research & Development and Environmental Safety
M. S. Molodtsev, Head of Ecological Safety Center, e-mail: molodtsevMS@kolagmk.ru

A long-term exploitation of the copper-nickel deposits situated in the Pechenga Ore Field led to the development of deeper levels with the following concentrations: 0.55–0.65 % Ni, 0.23–0.25 % Cu. Compared with the upper levels, these ore bodies have a bigger share of refractory ores which account for poorer processability of ore mixtures: copper recovery is 65–75 %, nickel recovery is 60–70 %; concentrate grade – 6.5–7Ni %. Analysis of the concentrator plant performance indicators helped establish optimum (with the share of ordinary ores being at least 50 %) and refractory ore mixtures. One of the prospective solutions for raising the recovery includes achieving a greater liberation of ore minerals and their aggregates due to refinement and size distribution optimization of flotation feed material. A more efficient concentration of refractory ores could be achieved due to the adoption of a process that involves a gradual removal of sulphides based on their floatability during two separate recleaner stages. The next step of the solution, which is based on gradual removal of sulphides and their high-grade aggregates at first signs of liberation, includes the adoption of staged flotation. The need to increase the throughput attributed to the need to maintain the metal output considering lower concentrations of non-ferrous metals in the mined ore and a greater share of refractory ores, determined the changes in the 1^st section flotation process, and namely the expanded recleaner flotation front. An expanded flotation front allows to increase the recovery of mineral particles (aggregates) with low flotation kinetics. The paper describes the work performed, as well as the results of pilot tests and pilot use of the modified concentration process. Optimization of grinding and flotation processes by revising the solution employed and through prior analysis of changes in the process serves as an effective tool for raising the refractory ore concentration efficiency.

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