Institute of Integrated Mineral Development – IPKON, Russian Academy of Sciences, Moscow, Russia:
A. A. Lavrinenko, Head of Laboratory, Doctor of Engineering Sciences, lavrin_a@mail.ru

The article describes the main issues connected with the recovery of gold and other high-valued elements from coal and coal combustion products as well as with the ash and slug reclamation. The thermodynamic modeling shows the variation of phase transformations in gold compounds depending on coal combustion temperature and on gold content of original coal. The boundary zone of gold transformation between solid and gaseous phases and backward is presented. It is described how silver compounds behave under thermal treatment of coal. Nonuniformity of gold distribution in coal fields is shown. After the systematic sampling at Nazarovskoe and Borodinskoe deposits, the elemental compositions of the samples are analyzed. Gold content of coal is determined at different depths at Nazarovskoe and Borodinskoe deposits in the Kansk–Achinsk Basin, and the gold-richest levels are identified. The process of the recovery of precious metals and other high-valued elements from coal and coal combustion products is justified and developed. The argumentation is provided for the method of gold by-production from smoke emission during coal combustion in grate-fired furnaces at the maximum yield of slug. A pilot installation based on a boiler plant with the grate-fired furnace for the gold recovery from smoke emission at a capacity of 500 m³/h is presented. Thiocarbamide leaching of gold and other high-valued elements from fly ash taken from electrical filters and from ground slag after lignite combustion with pre-removal of alkaline elements by sulfuric and chlorhydric acids has been carried out. The scope of the studies encompasses flotation of underburning with water-kerosene emulsion used as a collecting agent and with methyl-isobutyl carbinol (MIBC) as a frother, later-on leaching of the flotation concentrate using a complexing agent based on phosphinates, and the influence of difference factors on the efficiency of leaching and recovery of unburnt coal containing high-valued elements.

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