Mathematical model and factors of paste thickener rake torque
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摘要: 基于泥床料浆的非牛顿体特征,以及料浆初始剪切应力与浓度的变化规律,本文提出了耙架扭矩计算模型.模型预测结果显示,耙架扭矩随底流浓度升高而增大,底流浓度对浓密机运行时的扭矩百分比的影响幅度可达4.67%,两者呈现为多项式函数关系.与此同时,泥床高度对耙架扭矩影响较小,影响幅度仅为0.27%.通过某铅锌矿膏体浓密机64 h运行过程实时监测数据对比,验证了模型关于底流浓度和泥床高度对扭矩的影响规律.Abstract: In mining, cement paste backfill technology uses the high concentration tailings that remain after mineral processing to backfill underground stopes. These tailings are prepared by dewatering, mixed with a proportion of cement or other binder, then, after sufficient mixing, the saturated homogenized slurry is pumped or gravity-transported. Therefore, high concentration tailings are a prerequisite for cement paste backfill preparation and high quality backfill. The paste thickener is a key component that shows high efficiency dewatering, and rake shearing greatly affects tailings dewatering performance; therefore, appropriate rake torque design is crucial for efficient paste thickener operation. Rake torque is a key factor in determining the dewatering extent and the rate of flocculation in the networked structure bed in the thickener compression zone. In some industry processes, the problems of rake bogging, rat holing, swirl motion, and insufficient underflow concentration can affect production or seriously damage equipment. All these problems can be attributed to poor rake design or operation. Based on the non-Newtonian characteristics of a mud bed and the correlation of slurry initial shear stress with solids concentration, a torque mathematical model was proposed. The model predicted a rake torque increase with an increase in underflow concentration during thickener operation; the percentage of rake torque variation reached 4.67%. Regression analysis indicates that the percentage of rake torque presents as a polynomial function of the underflow concentration. At the same time, bed height affected rake torque slightly and the rake torque percentage varied within 0.27% when the bed height fluctuated. The predicted effects of underflow concentration and bed height on rake torque are confirmed and compared with 64 h of operational data on thickener operations in a lead-zinc mine.
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Keywords:
- tailings dewatering /
- rake torque /
- initial shear stress /
- bed height /
- underflow concentration
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