Tver State Technical University, Tver, Russia:

A. L. Yablonev, Head of Department, Associate Professor, Doctor of Engineering Sciences, alvovich@mail.ru

Pik Mining, Moscow, Russia:
P. B. Pashko, Engineer

The underground coal mining systems use powered roof supports to prevent roof collapse and to assist advance of conveyors. A powered roof support unit can hold 6 to 8 hydraulic cylinders, while a longwall mining system can contain 250 to 300 power roof support units. The efficiency of powered roof supports is largely determined by the quality of the working fluid—emulsion. Production of emulsions from imported water-soluble emulsols seems to be not a good solution currently, because of the significant increase in their cost and due to logistical difficulties. Therefore, it is relevant and expedient from the point of view of import substitution to produce emulsions directly in mines using special devices—dispersing tools utilizing the effects of ultrasound or cavitation. The article provides a description of the developed 7-block bench, including a dispersing tool capable of flow modulation, and using the effect of hydrodynamic and acoustic cavitation. Adjustment and control of cavitation is carried out by changing the content of free gas in the dispersing tool chamber. To calculate the working process, a mathematical model of uniformly distributed bubbles of free gas, synchronously oscillating as an ensemble of point sound sources of the monopole type, has been developed. The experimental study of the developed equipment during preparation of working fluid consisting of 98% water and 2% domestic EKS-A VVK emulsol shows that the dispersing tool with flow modulation allows single-cycle production of an emulsion with dispersivity 30–50% higher than a conventional hydromechanical dispersing tool enables. The analysis was carried out using MBI-6 electron microscope at 63-x magnification.

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