Test And Simulaiton Study Of Optimum Circulating Load In Close Grinding Circuits Of Fankou Plant

The circulating load in closed-circuit grinding is the main parameter which affecting thegrinding efficiency. This paper studied the mathematical relation between classificationefficiency and concentrations of the grinding circuit. The mathematical expressions of optimalgrinding circulating load were derived based on grinding kinetic equation and material balanceequation. The results showed that the optimum circulating load is closely related to theclassification efficiency. In the condition of best circulating load, the energy utilizationefficiency of grinding and classification circuit reaches the maximum.Taking Fankou lead-zinc mine for example, the different mill’s capacities ofhydrocyclones and spiral classifiers are studied, and the way that improving the classificationefficiency can improve the grinding efficiency is verified. The optimal circulating loads of firststage grinding and second stage grinding in Fankou lead-zinc are derived by simulationcalculation on the basis of test data.The study shown that, under the conditions of grinding granularity satisfied with theprocess requirements, compared with the results of spiral classifier, the classification efficiencyof hydrocyclones is increased by3.78%and the capacity per mill increased from42.7t/h to46t/h aftre the spiral classifier was replaced by hydroclones in first stage grinding. When thecapacity per mill is constant as46t/h, the fineness of-74μm content of overflow inhydrocyclones can reach70.54%, it increased5.95%, which compared with the result of spiralclassifier, and the related increasing ratio is9.21%. The neonatal ability of-74μm improves0.148t/(m~3·h) as relatively increasing11.18%. Improving of Classification efficiency andcirculating load optimization are important reasons for raising overflow fineness and-74microns newborn ability.The results of the simulation calculation of circulating load indicated that the optimumcylic load of the first stage grinding operation is approximately240%, under this condition, theclassification efficiency, the relative capacity and the total energy utilization efficiency are56.37%,1.4606and184.65kg/kW, respectively. The optimum cylic load of the second stagegrinding operation is approximately90%, in this case, the classification efficiency, the relativecapacity and the total energy utilization efficiency are48.83%,1.8871and449.60kg/kW,respectively.