Institute of Mining, Far East Branch, Russian Academy of Science, Khabarovsk, Russia:

V. S. Alekseev, Senior Researcher, Candidate of Engineering Sciences, alekseev-vs_83@mail.ru
T. S. Banshchikova, Senior Researcher

A significant part of industrial gold is contained in hard-to-recover, thin-plate, scaly forms, dendrites and fine particles that are lost with tailings during dressing by gravity. Water flows wash out mediumsized gold with a high flattening coefficient, which identifies the deformed surface belonging to the category of “rebellious” species. The Institute of Mining, FEB RAS, has developed several methods to extract gold from mining waste. The technologies are based on the application of: a halogen-containing reagent, which improves hydrophilic properties of gold; a natural sorbent, which allows extracting fine particles (70 microns or less); surfaceactive substances of anionic type–to reduce surface tension of water and to concentrate gold particles with a high coefficient of flattening. As a chemical reagent, the mixture of an alcohol solution of iodine and an aqueous solution of potassium iodide at a solid-to-liquid ratio of 1:2 and pH 7–9 is used. In the process of chemisorptions, a strong compound with an ion bond [AuI4]^– is temporarily formed on the gold surface to increase the hydrophilic property of gold. The high-scale technological tests of the proposed method have been carried out using the current tailings available the Solovievsky gold placer and at the other gold mining sites of Priamurye. With the above-described reagent used, the gold content has been increased and this fact has been observed at all five test sites, with the highest positive effect reached in case of the size grade -0.1 mm. For extracting gold from concentrates with amalgamation, the halogen-containing solution has been proposed, which makes it possible to exclude formation of mercury drop and to reduce metal loss. The use of surfactants and sorbents allows extraction of gold with a high coefficient of flattening, as well as fine particles from the silt-clay sediments. The proposed methods can be used for improving gold concentrates at any mine; the reagents need no extra energy input for preparation, are inexpensive, quite affordable and eco-friendly.

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