Analysis Of Grinding Efficiency And Key Parameters Influence Of Tower Mill

With the depletion of the free-milling minerals, the refractory minerals in which associated minerals are colsely embedded in target minerals are becoming more and more, and resulting in difficult subsequent classification. Therefore, it is necessary to carry out superfine grinding of those minerals. Tower mill which has high energy utilization rate and superior grinding mechanism has the most development potential as the superfine powder manufacturing equipment. But at present, the insufficient domestic research on the grinding mechanism of tower mill, lacking of the technical experience in design, the unclear section of parameters and the backward control technology result in low efficiency and high power consumption of tower mill. Those have seriously restricted the development of large tower mill. So the study on how to improve the grinding efficiency and reduce the power consumption of tower mill have great significance on breaking the monopoly of foreign technology and enhancing the level of production in domestic mines.The main factors influencing grinding efficiency of the tower mill include structure parameters, operating parameters and aggregate characteristics. The operating parameters mainly include:agitator speed, medium filling rate etc.; The structure parameters mainly include:helix angle of agitator, agitator diameter etc.; The aggregate characteristics mainly include:strength, hardness etc. Three important influence factors were chosen to analyze. The three parameters are agitator speed, media filling rate and helix angle of agitator.Firstly, the development history and the current application situation of the tower mill at home and abroad were introduced, and then the research direction of this topic were put forward. Secondly, this paper gave a brief introduction of the grinding mechanism of the tower mill, and analysed the grinding efficiency effect of the key parameters from the view point of mathematical deduction and theoretical modeling. These provided some theoretical guidance for the follow-up simulation analysis and experimental study. Again, the EDEM software was used to evaluate the grinding efficiency effect of the key parameters from the normal and tangential impact force, collision frequency and energy consumption. On the basis of the above theoretical analysis, the experimental tower mill was used to experiment the efficiency effect of the three key parameters. The laser particle size analyzer was used to measure the aggregate size after the experiment and the energy consumption of the experimental groups were recorded. By the above analysis, it is concluded that the optimal operation speed of the tower mill is slightly higher than the critical cycle speed meanwhile the media balls do not appear the suspension phenomenon, this paper takes 210rpm; The strength of the single load will be reduced and the effective collision will be insufficient and the collision energy loss will be serious if the media filling rate is too high. The frequency of the load will be low and the minerals will not be broken if the media filling rate is too low, this paper takes 60%; Grinding efficiency increases when the helix angle is reduced, but the helix angle is inversely proportional to the critical cycle speed, so its value should not be too low, this paper takes S/D=0.8. Finally, the conclusion drawn from the analysis were used for the large-scale design of the tower mill, and the structure strength check of the stirrer was carried out.The influence of the three key parameters on the grinding efficiency of the tower mill were studied through the combination of the mathematical modeling, DEM simulation and experimental analysis which enhances the reliability of the analysis and makes the conclusion more persuasive. At the same time, it has more reference value for the large-scale design of tower mill.