Abstract
Deep cone thickener (DCT) is key equipment in cemented paste backfill (CPB) technology. However, rake blockage occurs frequently in DCT during the dewatering process of the unclassified tailings being thickened from dilute slurry to thickened tailings or paste. Rake blockage has disastrous effects on the CPB operation. In order to investigate the influencing factors of rake blockage in DCT, a mathematical model of rake power in DCT was developed. In addition, stacking mud bed (made of thickened tailings) from the DCT in Huize lead-zinc mine (HLZM) in different rake blockage accidents was sampled and tested to investigate the effect of tailings characters on rake blockage. Results indicated that the concentration of the mud bed and the friction between the mud bed and the cone wall contributed to the rake blockage. The concentration and friction were influenced by the high content of coarse particles in the mud bed. Moreover, activating devices for bed mud, as the corrective and preventive action, were developed to prevent the rake blockage, which was valid in HLZM.
Highlights
Millions of tons of ore are processed annually to meet the economic demand and social development, accompanied with unprecedented worrying of the accumulation and increment of solid waste [1]
The deep cone thickener (DCT) that produces a high concentration underflow is employed to consolidate the unclassified tailings from a dilute slurry to thickened tailings [13, 14], which is the key to cemented paste backfill (CPB) [15, 16]
Rake torque is a key parameter in DCT design and operation which is mainly influenced by the yield stress of the suspension [17]
Summary
Millions of tons of ore are processed annually to meet the economic demand and social development, accompanied with unprecedented worrying of the accumulation and increment of solid waste (waste rock or tailings) [1]. Using laboratory experiments and numerical simulation, many studies focused on the influence on thickening performance, rake torque calculation, and rake design. Rake torque is a key parameter in DCT design and operation which is mainly influenced by the yield stress of the suspension [17]. To produce high concentration underflow, the yield stress of underflow in DCT is much higher than conventional high-rate thickeners, resulting in a much higher rake torque demanding for DCT [25]. The yield stress of the suspension, rotation speed, and rake structure have great influence on rake torque [26]. Wu et al [27] proposed a torque model for complex structure rakes based on the influence of slurry concentration on rake and height of the bed. Tan et al [28] formulated a rake torque model as a function of solids concentration, which pays more attention to underflow solids concentration rather than rheological properties and overcomes the shortcomings of yield stress measurements
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