赤铁矿磁选-浓密-浮选过程中浓密机的底流矿浆浓度受到大而频繁的浮选过程产生的中矿矿浆随机干扰的影响，造成底流矿浆流量频繁波动在工艺规定的范围之外，使得矿浆在浮选机中选别时间缩短，液位波动造成有用金属流失，从而减少精矿品位和金属回收率。本文分析了难以采用现有的底流矿浆浓度闭环控制策略的原因，提出了由流量设定和跟踪流量设定值控制组成的矿浆浓度与流量区间双闭环控制；提出了基于静态模型的流量预设定、模糊推理的流量设定补偿、流量设定保持器和规则推理的切换机制组成的流量设定智能切换控制方法。与矿浆浓度闭环控制方法的仿真对比实验和在国内某大型赤铁矿混合选别浓密机的成功应用，表明所提出的方法在浮选中矿干扰下，不仅将底流矿浆浓度和流量控制在目标值范围内，而且明显减少底流矿浆流量波动，从而在保证金属回收率不变的条件下，显著提高了精矿品位。%In the mixed separation thickener (MST) of hematite beneficiation, since the underflow slurry concentration (USC) is influenced by some large random disturbances, the underflow slurry flowrate (USF) frequently fluctuates outside the technologically specified range so as to decrease the flotation time and cause flotation machine level fluctuations. Hence, the concentration grade and metal recovery percent are influenced remarkably. This paper firstly analyzes the reason why the existing USC close-loop control strategy is difficult to adopt. Then a two-layer hierarchical control structure based on the USF setpoint control and tracking USF setpont control is proposed, and the intelligent switching control method is proposed which includes a USF presetting based on the static model, a USF setpoint compensator based on fuzzy reasoning, a retainer of USF setpoint and a switching mechanism based on rule reasoning. A simulation to compare the proposed method with the USC setpoint control strategy and a successful application of the proposed in a domestic hematite concentration plant have shown the effectiveness of the proposed method. Moveover, the application results demonstrate that the fluctuations of USC and USF have been significantly reduced, and the underflow slurry quality has been guaranteed. As a result, the concentration grade and the recovery percent have been improved.
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