Saint-Petersburg Mining University, Russia:
V. V. Lvov, Associate Professor, Candidate of Engineering Sciences, opilvv@mail.ru
T. N. Aleksandrova, Head of a Chair, Doctor of Engineering Sciences

Ore pretreatment improvement remains yet the most important objective in the mining industry. Processes of classifying in hydrocyclones are of no little significance in mineral grinding, especially in the closed circuit grinding. Operation of cyclones often suffers from low efficiency when properties of feed materials change: solids content, slurry viscosity, grain-size composition. This may cause considerable complications to the process, such as different cut point, slope of separation curves characterizing cyclone separation. Stable classifying using hydrocyclones is the important production task. Underflow of a complete cyclone-and-grinder circuit can be discharged using a rope or an open umbrella. Each of these types of discharge has benefits and shortcomings. The optimized separation is achieved at the transition point between the two types of underflow discharge. The stable and optimized separation using cyclones is feasible through the application of the proposed automated control method. The method consists in measuring the slurry flow rate in cyclone overflow and underflow, the slurry viscosity and the width of opening of the underflow umbrella using a contactless sensor. Depending on the measured values, the cross-section of the outflow nozzle is changed using a special device. The stabilization circuit accounts for boundary grain diameter, considering current viscosity of slurry. The application of this automated control method will enable improved performance of hydroclassifying owing to stabilization of cut point of hydrocyclones.
This study has been carried out in the framework of the project part of governmental assignment for research activity (Assignment No. 5.1284.2014/K dated July 11, 2014).

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