Comparative Study of Grinding Efficiency of Steel Balls and Steel Cylpebs Based on Ball Mill Scale-up Mathematical Model:Taking Tungsten Ores as Example
There is long-standing controversy over the difference in grinding efficiency between steel balls and steel cylpebs as grinding media.This paper compares the performance of steel balls and steel cylpebs in laboratory ball mill and in-dustrial grinding circuit based on laboratory experiments and grinding process simulations.An enhanced Bond Ball Mill Work Index test was conducted on a tungsten ore from Yunnan province,and the Perfect Mixing Model was used to calculate the breakage rate parameter(r/d)of the two grinding media in laboratory experiments.The circulation ratio and product particle size of industrial-scale ball mill grinding circuits were predicted using a ball mill scaling-up model,based on the breakage rate parameter obtained from laboratory experiments.The results show that,although the two media can achieve similar Bond Ball Mill Work Indices in laboratory experiments,the breakage rate parameter of steel cylpebs is greater at the coarse end than that of steel balls,while the opposite is true at the fine end.In industrial-scale ball mill grinding circuit,when the circulation ratio is similar,the particle size distribution of overflow products from cyclone separators produced by the two media is relatively simi-lar.However,compared with steel ball media,the product particle size distribution of steel cylpebs is more uniform,with less coarse and fine particles than steel ball products.Due to the differences in the shape of the final product particle size distribu-tion curve,the comparison of grinding efficiency between steel balls and steel cylpebs may be influenced by the selection of grinding fineness measurement indicators(P80 or-0.075 mm content).Therefore,the decision as to which grind fineness measure to use for evaluation should be made in the context of the actual liberation characteristics of the ore and the specific requirements of the flotation operation.
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