Shilo North-East Interdisciplinary Research Institute, Far East Branch, Russian Academy of Sciences, Magadan, Russia:

T. I. Mikhalitsyna, Senior Researcher, Candidate of Geological and Mineralogical Sciences, mihalitsina@neisri.ru
O. T. Sotskaya, Researcher, Candidate of Geological and Mineralogical Sciences, sotskaya@neisri.ru

Matrosov Mine, Magadan, Russia:

E. M. Nikitenko, Deputy Director, Candidate of Engineering Sciences, elena_mih-na@mail.ru

The article describes the analytical, mineralogical and technological studies into enclosing rocks of Degdekan gold deposit. It is found that ore composition is dominated by silicon oxide (62.2–70.4 %), the ore-forming minerals are mainly iron, sulfur and arsenic in sulfide and oxide forms. The clustering analysis distinguishes three representative geochemical associations: Au-Ag-Pb-Sb; As-Mo-Cu; Co-Ni-Cr-Zn-W. Mineralization is pyrite, arsenopyrite, free gold, seldom fahlore, pyrrhotine, chalcopyrite, galena, sphalerite, etc. Pyrite contains As and Ni impurities. By the criteria of association and recovery, gold is present in 4 varieties: free gold recoverable by amalgamation and cyanation; fine gold associated with sulfides and disengageable after oxidizing roasting; fine and very fine gold associated with iron hydroxides, carbonates and chlorites, and extractable in cyanation after HCl treatment; fine gold associated with carbon black and recoverable by cyanation after oxidating roasting at a temperature of 650 °C. The bulk (from 41.6 to 86 %) is represented by free gold extractable in cyanation and gravity separation. This gold features large particles and occurs at the zones of quartz veins, both in veins and in strings. Percentage of fine gold (–0.04 mm) in metasomatic quartz–cericite rocks (nearby veins) varies from 2 to 11 %. There are also platinoid group metals, highly concentrated in sulfide concentrates. Potential resources of platinoids as associated metals are estimated as 10 t (around 10 % of gold resources). The authors arrive at the conclusion on feasibility of joint concentration of gold and platinoids in an integrated process circuit by gravity separation with end product as a Doré bar containing platinoids.

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