黏结理论及离散元法在半自磨机衬板设计中的应用研究

发布时间：2018-08-01 11:37

【摘要】：半自磨机属于大型磨矿设备,由于其规格大,处理能力强,工艺流程简单,易于实现自动化等特点,被越来越多的大型选矿厂所使用。但也正是因为其规格大的特点,使得半自磨机筒体衬板磨损过快,需要频繁的对其进行更换和维修,从而造成半自磨机作业率低下的问题。据统计,采用半自磨回路系统的选矿厂的作业率都达不到80%,而采用传统球磨回路系统的选矿厂的作业率能达到95%。因此对半自磨机的筒体衬板进行结构改进,以延长衬板的使用寿命,对提高半自磨机的作业率显得至关重要。根据对国内某大型铜矿的调研发现,处理量、能耗及产品粒度三个主要性能指数都随着半自磨机筒体衬板的不断磨损而有所提高,而磨损后的筒体衬板与球磨机所使用的波形衬板相似。本文以离散元理论为基础,结合BPM黏结理论,建立了矿石的BPM黏结模型,该模型弥补了破碎概率模型适用性差的缺陷,同时解决了临界比能法忽略破碎能随矿石粒度变化的不足,采用该方法可分析衬板的有效碰撞能和黏结键的断裂数目。通过将EDEM与ANSYS耦合,对衬板的等效应力及其分布进行了研究,解决了 EDEM软件可视化性能差,处理步骤繁琐的缺点。采用Archard wear磨损模型分析了衬板的磨损量,该方法可以定性的分析衬板的磨损量和磨损区域,对研究衬板的磨损原理,提高衬板磨矿性能和耐磨性能具有重要的价值和工程意义。通过分析黏结键的断裂数目和有效碰撞能量,发现梯形衬板对矿石的提升能力更强,但波形衬板的破碎效果更好。从静力学分析的结果得知梯形衬板在棱角处和提升条与基底过渡位置易出现应力集中,而波形衬板的应力分布均匀,且在提升条相同位置处,波形衬板的应力远小于梯形衬板。从衬板磨损量的分析结果可知梯形衬板的磨损量更小,使用寿命更长。结合以上的研究成果,本文认为在设计梯形衬板时,应将其设计成分体式,且棱角处做圆角处理;设计波形衬板时,应在主提升条的两侧各添加一个辅助提升条,辅助提升条的尺寸为主提升条的1/3。同时为了验证上述设计方法的正确性,对新型衬板和原始衬板进行了对比分析,发现新型衬板不论是在磨矿效果还是耐磨性能方面都有较大的提升。
[Abstract]:Semi-autogenous mill is a kind of large-scale grinding equipment, which is used by more and more large concentrators because of its large size, strong processing ability, simple technological process and easy to realize automation. However, it is precisely because of its large specifications that the liner of the semi-self-grinding machine is worn too fast, which needs to be replaced and repaired frequently, resulting in the problem of low working rate of the semi-self-grinding machine. According to statistics, the operation rate of the concentrator using semi-self-grinding loop system is less than 80%, while that of the traditional ball mill circuit system can reach 95%. Therefore, it is very important to improve the structure of the cylinder liner of the semi-self-grinding machine to prolong the service life of the liner and to improve the working rate of the semi-self-grinding machine. Based on the investigation of a large copper mine in China, it is found that the three main performance indices, such as treatment capacity, energy consumption and product granularity, all increase with the continuous wear of the liner plate of the semi-self-grinding machine. The worn cylinder liner is similar to the corrugated liner used in ball mill. Based on discrete element theory and BPM bonding theory, a BPM bonding model of ore is established in this paper. The model makes up for the defect of poor applicability of fracture probability model. At the same time, the shortage of critical specific energy method neglecting the change of breakage energy with the change of ore particle size is solved. The effective impact energy and the number of bond fracture of lining plate can be analyzed by using this method. By coupling EDEM and ANSYS, the equivalent stress and its distribution of liner are studied, which solves the disadvantages of poor visualization performance and tedious processing steps of EDEM software. The wear quantity of liner is analyzed by Archard wear model. This method can qualitatively analyze the wear quantity and wear area of liner. It is of great value and engineering significance to study the wear principle of liner and improve the grinding and wear resistance of liner. By analyzing the number of bond fracture and the effective collision energy, it is found that trapezoid liner has stronger lifting ability to ore, but waveform liner has better crushing effect. The results of statics analysis show that the stress concentration of trapezoidal liner is easy to occur at the corner and the transition position between lifting bar and base, but the stress distribution of corrugated liner is uniform, and the stress of corrugated liner is much smaller than that of trapezoidal liner at the same position of lifting bar. The results show that the wear of trapezoidal liner is smaller and the service life is longer. Combined with the above research results, this paper holds that when designing trapezoidal liner, it should be designed as a split type, and the edges and corners of the plate should be rounded, and when designing the corrugated liner, one auxiliary lifting bar should be added to each side of the main lifting bar. The size of the auxiliary lifting bar is mainly one third of the lift bar. At the same time, in order to verify the correctness of the above design methods, a comparative analysis is made between the new type liner and the original one. It is found that the new type liner has a great improvement in both grinding effect and wear resistance.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD453

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