Kroosh Technologies ltd, Ashdod, Israel:

G. M. Kosoy, Chief Ore Concentration Specialist, Doctor of Technical Sciences, e-mail: grigory.k@kroosh.com
A. Ya. Vinnikov, Project Leader, Candidate of Technical Sciences

This paper describes high-frequency screens developed by Derrick and Landsky and multi-frequency screens developed by Kroosh Technologies, how they function and the differences between them. The fundamental difference between the vibration parameters in the high-frequency and multi-frequency modes is the difference in the accelerations created by the vibration excitation system. In high-frequency screens, the maximum acceleration of the screening media does not exceed 10g. In multifrequency screens, the measured positive and negative accelerations of the screen body are 3g. However, when interacting with the developed system of multi-frequency vibration, the positive peak accelerations of the screen mesh reach (50÷60)g, and the negative accelerations — (150÷200)g. This mode ensures that the screening media are kept free from material, and thus the specific throughput and the screening efficiency rise. A few dozens of tests with different ores were carried out on a pilot unit. The paper describes some qualitative and quantitative results of hydraulic screening of finely ground ores with 75 and 100 micron media, which were obtained on a pilot unit with a 1,500×600 mm multi-frequency screen. As a result of hydraulic screening of ground chrome ore with a 0.1×2.6 mm mesh at the ore feed rate of 2.65 t/(h·m²), the undersize product included 91.8% of particles smaller than 100 microns. With the hydraulic screening of ground chrome ore with a 0.075×2.6 mm mesh at the ore feed rate of 1.66 t/(h·m²), the recovery of particles smaller than 75 microns as the undersize product was 88.78%. With the hydraulic screening of ground tin ore with a 0.1×2.6 mm mesh at the ore feed rate of 2.94 t/(h·m²), the recovery of particles smaller than 100 microns as the undersize product was 93.93%. Multi-frequency screens are successfully used by the concentrator plants of Kazzinc and Glencore (South Africa).

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