OPTIMIZATION OF GRAIN SIZE FOR HEAP LEACHING OF GOLD ORE IN MULTI-LEVEL STOCKPILES

Heap leaching of gold is applicable to large and small deposits, to low gold content ore, to overburden dumps and metallurgical processing waste. Optimization of ore grain size will enable better recovery of gold from multi-level stockpiles. The dominant influence on the final grain size is executed during ore pre-treatment. Then, the method of heap leaching takes a special place as the pre-treated stockpile parameters are invariable for the entire long-term period of leaching. Pre-treatment of gold ore down to a wanted grain size by crushing, pelletization or de-sliming (removal of silt and clay fractions) during stockpiling should ensure uniform distribution of leaching solution at the required permeation rate (1–2 m/day).
Grain size of ore in many dumps of open pit gold mines is 200 mm and more. As a consequence, gold is unleached from such coarse particles as access of active agents is restricted by thick layers of mineral matrix. Vice versa, mill tailings feature over-grinding, which results in over-sliming during treatment by leaching solutions and, consequently, in reduced permeability as clay fractions impede seepage. In terms of the Muruntau deposit, the relationship between the finely dispersed gold recovery and the degree of ore size reduction is determined, and it is shown that it is economically profitable to grind ore grains less than 3.35 mm in size in amount of 90 % of total volume, which will enable heap leaching of ore with gold content less than 0.65 g/t at the average price of $ 1260 per ounce.

Keywords

Нeap leaching, ore, ore pre-treatment, ore stockpile, coarseness, gold recovery, grain size, crushing, small fraction, additional crushing, agglomeration, leaching solution flow, crushers, autogenous grinders, roller press, microcracks, leaching rates, grain-size composition, multi-level stockpiling, cement, gold recovery increment.

Issue number: 2
Year: 2019
ISBN: 622.732
UDK:
DOI: 10.25018/0236-1493-2019-02-0-172-180
Authors: Norov Yu. D., Borovkov Yu. A., Derevyashkin I. V., Yakshibaev T. M.

About authors: Norov Yu.D., Doctor of Technical Sciences, Professor, Head of Mining Bureau, Central Research Laboratory of NGMK, Borovkov Yu.A. (1), Doctor of Technical Sciences, Professor, e-mail: bua_51@mail.ru, Derevyashkin I.V., Doctor of Technical Sciences, Professor, Head of Chair, Moscow Polytechnic University, e-mail: gornoedelo-um@mail.ru, Yakshibaev T.M. (1), Graduate Student, MGRI-RGGRU, e-mail: temur19.01.1988.tm@list.ru, 1) Russian State Geological Prospecting University named after Sergo Ordzhonikidzе (MGRI-RSGPU), 117997, Moscow, Russia.

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