National University of Science and Technology MISIS (Moscow, Russia):

Dumov A. M., Associate Professor, Candidate of Engineering Sciences, amark1@mail.ru

This paper covers the results of laboratory experiments for combined generation of garnet-almandine concentrates through gravitational, magnetic, corona-electrostatic and triboelectrostatic processing. The raw material was represented by natural concentrated material from one of the garnet placer deposits of the White Sea coast. The garnet-almandine mass fraction was approximately 65 % against the usual value of 12–24 %. The main impurities were represented by quartz, amphiboles, magnetite and ilmenite. Amphiboles were represented by hornblende, characterized by widely varying magnetic response values depending on the iron content. The grain size of the material was 0.1 to 0.5 mm, including over 92 % in the range 0.2 to 0.4 mm. The traditional processing method was used for the raw materials. Preliminary gravity concentration was carried out on an SKL-2 concentration table with the yield of coarse concentrate. Magnetite and scrap were isolated from the gravity concentrate by first-stage magnetic separation in a weak field and disposed of as tailings. Separation in a strong magnetic field with a 138 SE separator was used to isolate ilmenite, garnet and part of ferruginous hornblende from the non-magnetic fraction of the first stage. The best possible magnetic field strength was determined. Ilmenite was effectively separated from the garnet in a ES-3 corona-electrostatic separator. The optimum parameters for the operation of the corona-electrostatic separator were established. The recovery of garnet into the concentrate was approximately 88 % with the mass fraction of 90.5 %. The main impurity was represented by ferruginous hornblende. No commercial grade garnet concentrate was obtained. Experiments were carried out with the aim to treat the resulting product to the commercial grade using triboelectrostatic separation in an ERTS separator. The optimum operating mode was selected for the separator. The best result consisted in the recovery of commercial grade garnet concentrate with the mass fraction of garnet of 97 %, with the yield value of 83 % of the gravity concentrate.

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