【作者】 刘磊；

【导师】 吕宪俊； 邱俊；

【作者基本信息】 山东科技大学 ， 矿物加工工程， 2009， 硕士

【摘要】 本文采用“旋流器-浓密机”两段分级浓缩工艺对某铁矿尾矿进行了浓缩工艺优化研究,为高浓度尾矿的制备奠定了基础。为了保证全尾矿分级浓缩系统的高效稳定的运行,对全尾矿分级浓缩系统进行了自动控制技术研究。在系统分析浓缩型旋流器给矿压力、进料浓度、溢流口直径、底流口直径等对旋流器浓缩效果的影响规律的基础上,提出了影响旋流器浓缩效果的关键因素及其影响规律。在实际操作中,可通过调节旋流器底流口和给矿压力的大小来控制底流浓度。为保证较高的底流浓度和底流产率,旋流器底流的排放状态应处于大角度伞状与拧绳状之间的过渡状态。当旋流器给料浓度为20%左右时,旋流器底流浓度可达到65～70%、底流产率可达到63～67%。进一步采用正交回归试验方法,得出了旋流器的底流浓度、底流产率、处理量与旋流器的底流口直径和给矿压力之间的回归方程,为旋流器浓缩系统的自动控制提供了理论依据。采用无耙高效浓密机对微细粒旋流器溢流进行了浓缩试验。研究表明,采用絮凝沉降的方法能够显著提高微细颗粒的沉降速度,絮凝剂的最佳用量为20-30g/t。通过对给料浓度、给料流量和底流流量对无耙高效浓密机底流浓度的影响规律研究,提出了通过控制浓密机底流流量来控制底流浓度的方法,得出了底流浓度与底流流量之间的回归方程,为无耙高效浓密机的底流浓度的控制提供了依据。结合全尾矿分级浓缩系统的特点,首次提出了浓缩型水力旋流器和无耙高效浓密机的自动化控制方法。采用三段“液位闭路反馈”控制给料泵池液位、两段PID控制输出调节给料变频器频率的方法,控制浓缩型水力旋流器的浓缩效果和工作状态稳定;采用调节底流流量的方法控制无耙高效浓密机的底流浓度。选用PLC为控制系统的控制器,结合液位、压力、流量等检测变送器和变频器、电动阀等执行器完成控制系统的检测、控制和执行功能。采用STEP7-Micro/WIN32编程软件实现了PLC控制程序的编程、下载和运行等功能;采用组态王KingView监控软件实现了上位机与PLC的通讯、系统自动启停、在线检测与执行、人机对话和系统报警等功能。对25t/d尾矿分级浓缩中试系统进行自动控制的设计和应用。结果表明:采用自动控制后,当给料浓度20.47%时,旋流器的底流浓度达到68.46%、底流产率达到66.31%;旋流器溢流经过一段浓密机浓缩后浓度达到36.33%,尾矿最终的浓缩浓度达到52.75%。在保证浓缩系统稳定工作的前提下,实现了全尾矿的高效浓缩。更多还原

【Abstract】 The optimization of the thickening process of an iron ore tailings was studied by the two-stage classified thickening process consisting of "hydrocyclone-thickener", which established the base for the preparation of high density tailings. In order to make the stability operation of the total tailings thickening system, the automatic control technique for the thickening system was researched.Based on the theoretical analysis, the factors influencing the performance of hydrocyclone thickenning included feed pressure, feed concentration and the diameters of overflow and underflow outlet. In the practical operation, the concentration of underflow can be controlled by adjusting the diameter of underflow opening and feed pressure. In order to insure the high underflow concentration and capacity, the discharge state of the underflow should keep the inter-gradation between the big-angle-umbrella-shape and the rope-shape. When the feed concentration was about 20%, the underflow concentration can reach 65-70%, and the capacity of underflow can reach 63-67%.The regression equations between thickening effects including underflow concentration, underflow yield, capacity and factors comprising of underflow diameter and feed pressure were obtained by the orthogonal regression concentration experiments of hydrocyclone, which provided a theoretic basis for automatic control of classified thickening system.The micro-grained overflow of hydrocyclone was carried the concentration test by ’rake-less high-efficiency thickener. The research showed that the sedimentation rate can be improved greatly by the method of flocculation sedimentation, and the optimal dosage of flocculants was 20-30g/t. Based on the regulation of feed concentration and feed capacity, underflow capacity influencing the underflow concentration of rake-less high-efficiency thickener, the method of controlling the underflow concentration by controlling the underflow capacity was suggested, and the regression equation between the underflow concentration of rake-less high-efficiency thickener and flow rate of underflow was achieved, which brought theoretic basis for the automatic control of the rake-less thicker. Combining with the characteristic of total tailings thickening system, the automatic control methods of hydrocyclone and rake-less high-efficiency thickener were put forward at the first time. Hydrocyclone was controlled through the methods that three closed-loop feedbacks of liquid level were carried out to control the level of the feed pump pool, and two PID control outputs were implemented to regulate frequency of the feed converter; the underflow concentration of rake-less high-efficiency thickener was controlled through the method of regulating the flow capacity of underflow. The detecting, controlling and performing functions were achieved by the PLC controller, sensors of liquid lever, pressure and flow capacity, and actuators which comprise of converter and electric valve. STEP7-Micro/WIN32 was used to realize the program, download and run of PLC controlling program; KingView was used to achieve functions composed of communication between PC and PLC, automatic start-stop of system, on-line detection and execution, man-machine conversation, and system alarm.Automatic control of tailing classified thickening pilot system of 25t/d was designed and applied. The experiments showed that after applying the automatic control, the concentration and yield of hydrocyclone underflow can reach 68.46% and 66.31%, while the feed concentration was 20.47%; After one-stage concentration of thickener, the overflow concentration of hydrocyclone was 36.33% and the ultimate concentration of tailings was 52.75%. Under the premise that the thickening system ran stability, the efficient concentration of total tailings was achieved.更多还原