Chovan M., Jágerský I., Delaney V., Žitňan P., Kubač A., Bačík P., Troppová D. & Mikuš T. , 2016: Mineralogy of ore dressing products from Banská Hodruša Au (Ag, Pb, Cu) epithermal deposit. Acta Geologica Slovaca, 8, 2, 203–216.

Mineralogy of ore dressing products from Banská Hodruša Au (Ag, Pb, Cu) epithermal deposit

Martin Chovan¹, Ivan Jágerský², Vivien Delaney³, Peter Žitňan², Alexander Kubač⁴, Peter Bačík¹, Danka Troppová⁵ & Tomáš Mikuš⁵

¹Department of Mineralogy and Petrology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia; chovan@fns.uniba.sk
²Slovenská Banská Ltd., 966 61 Hodruša-Hámre, Slovakia
³SGS Canada Inc., P.O. Box 4300, 185 Concession Street, Lakefield, Ontario, Canada
⁴Department of Economic Geology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia
⁵Earth Science Institute of Slovak Academy of Sciences, Ďumbierska 1, 974 01 Banská Bystrica, Slovakia

Abstract

Gold–sulphide ore from epithermal vein deposit Banská Hodruša consists of gold, electrum, galena, sphalerite, chalcopyrite, and pyrite. Minor amounts of tellurides are present in the form of hessite, petzite and other rare Au sulphides and tellurides. Pyrite as a common product of hydrothermal alteration occurs mainly in the wall rock. Gangue minerals are represented by abundant quartz and adularia, clay minerals and carbonates. A combination of classical mineralogical methods – optical microscopy, electron microprobe, scanning electron microscopy, powder X-ray diffraction, automated mineralogy methods – QUEMSCAN RMS, TMS, PMA, and chemical analysis were used to determine composition of the head sample and individual ore dressing products, such as mineral jig concentrate, flotation concentrate and waste. The information about mineral composition of head sample, distribution of minerals in ore dressing products, their chemical composition and optimal grain size (P_85–88 of 74 μm) has been determined. The concentrate contains approx. 15 % of gangue minerals and approximately 2.5 % of the waste consists of sulphides. The mineral associations and mineral intergrowns has been studied. Gold is liberated well, with more than 70 % of gold being liberated and amenable to flotation, the rest associated with complex mineral assemblages (18 %), silicates and carbonates (9 %) and sulphides (~3 %). Liberation of sulphides is better than 83 %. The ore has excellent metallurgical properties, maximum achievable gold recovery by flotation is 96–98 %. Results of the study provided information to optimize ore dressing processes, particularly quality of milling, effectiveness of flotation process and gravity circuit.

Key words: epithermal mineralization, flotation, gold recovery, grain size, association, liberation

Manuscript received: 2016-08-24

Revised version accepted: 2016-10-10