Mining Institute, Far Eastern Branch of the Russian Academy of Sciences

The problem of processing sands from polymineral placer deposits of the Far Eastern region is a complex technical and technological process. The predominance of high-clay placers with high content of valuable components of small and thin fractions is noted. At the same time the content of fine gold fractions smaller than 0.5 mm reach more than 90 % at some sites with the predominance of fractions smaller than 0.3 mm. The necessity to improve the technologies and technical facilities for processing placer high-clay sands with a high content of fine and nanoscale particles of valuable components is substantiated. Therefore, the purpose of the study is to substantiate approaches to the construction of a phenomenological model for processing of placer high-clay sands by gravitational methods to ensure safety of crystals and reduce the loss of valuable components with reduced energy intensity. On the basis of the proposed exponential dependence of variation of specific interfacial surface of mineral particles on system thermodynamic potential, it has been found out that interdependence of hydraulic fluid efflux and flow rates plays a decisive role in microdesintegration of mineral particles under conditions of turbulization initiated by the jet falling on the flat surface of the cavitation reactor. The calculations performed allowed to estimate the growth of the specific interfacial surface of particles in the intervals of 1.8–3.3 times depending on regulation of hydraulic fluid flow rate, its density and initiation time. Presented mathematical dependencies will allow to control the process when testing cavitation reactor, assess installation quality and operation nature, as well as adjust the design and introduce necessary changes. We propose a general processing scheme for placers with the use of a number of innovative installations of a new type including those based on the combination of turbulence and cavitation at low energy intensity. The impact of hydrodynamic effects initiated by turbulent effects and cavitation on hydraulic fluid of high-clay sands is able to ensure reliable microdesintegration-dispersion and provide a significant reduction in technological losses of valuable components. The study results obtained can be used for further development of theoretical approaches to the description of cavitation processes modeled in proposed installations.

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