Study on Separation characteristics of dense medium cyclone for raw coal with high density fraction contents

This study attempts to enhance the separation efficiency of dense media cyclone for raw coal feed with difficult-to-cleaning and large high-density component content. Specifically, this paper 1) designed a novel heavy media cyclone model device, 2) established a mathematical model of sedimentation separation of particles in the centrifugal rotating flow field, 3) investigated the separation characteristics of the new dense media cyclone by combining experimental research and theoretical analysis, which revealed the separation variation patterns of raw coal difficult to select with high content heavy density components under different process parameters, 4) explored the factors affecting the dynamic stability of the working suspension in the flow field of the new heavy media cyclone and the discharge and transportation mechanism of heavy products. Results show that when the new dense media cyclone separates raw coal with high content of heavy density components, underflow heavy products exhibit stronger discharge capacity and higher processing capacity, while the centrifugal swirl field shows smaller density gradient distribution of suspension, more uniform density distribution, lower value of the difference between the underflow and the overflow density, as well as stronger stability of the suspension in the flow field. The feeding pressure is directly correlated with the dynamic stability of the suspension, separation accuracy and the discharge efficiency of heavy products. With increasing feeding pressure, the suspension discharged from the underflow and overflow port shows increased density difference, reduced possible deviation E value, improved separation accuracy and elevated amount of heavy product discharged. When the feeding pressure is 25 kPa, the actual separation density is 1.666 g/cm3, the possible deviation E value is 0.09 g/cm3, and the yield of heavy products is 75.23%, which provides new insights into the separation of raw coal with high content, heavy density components.