Key Technologies Research On Improving Processing Capacity Of Large-scale Ball Mill

Grinding is an indispensable precondition of mineral separation.Operation conditions of ball mills in a concentrator directly affect the processing capacity and economic benefits.In recent years,the size of ball mill tends to become large,so researches on the development and application of large-scale ball mill attract more focus both at home and abroad.Optimumization of grinding parameters such as media size,media size ratio,media charge ratio,rotation speed ratio,material-ball ratio and grinding concentration for a large-scale ball,playing an important role in optimizing grinding index,achieving greatest processing capacity and inproving grinding efficiency mill,becomes a research focus,.In this paper,ball mills of ?5.498.83m in Qidashan mineral processing plant of Anshan Iron and Steel Group was taken as research object,process mineralo gical investigation,physical and chemical analysis,bond work index simulation of processing capacity and motor power consumption combined with beneficiation process investigation was used to identify the reason for lower mill capacity;experiments on media size,media size ratio,media charge ratio,rotation speed ratio,material-ball ratio and grinding concentration were conducted to determine optimum laboratory grinding process parameters in Qidashan iron ore.On the basis,reasonable optimization scheme was put forward and systemic optimization technology of large ball mill for iron ore dressing plant was formed.At last the industrial test was carried out,making specific mill processing capacity up to about 350t and forming systemic optimization techniques of large-scale ball mills in iron ore dressing plant.In this paper,process mineralogical investigation of Qidashan iron ore was researched in detail.Process mineralogy characteristics of Qidashan iron ore showed that the total iron grade was 31.13%,mainly existing in hematite and magnetite.The magnetite particle size mainly disseminated in coarse grains,easier to achieve mineral liberation.Hematite mostly existed in media disseminated grain size,nouniform particle size distribution,increasinggrinding difficulty.And some fine vein of limonite were often filled with some hematite,difficult to liberate from from hematite,thus influencing iron recovery.Laboratory grinding experimental research results showed that media size,media size ratio,media charge ratio,rotation speed rate,material-ball ratio and grinding concentration could affect grinding effect a lot.Selecting appropriate media size ratio and media charge ratio,increasing media charge ratio material-ball ratio and rotation speed and adopting suitable grinding concentration was beneficial to improve the grinding effect.Three mono-size fractions(-6.0+4.0,-4.0+2.0,-2.0mm)were prepared in a laboratory-scale ball mill for determination of the grinding kinetic parameters.The optimum grinding conditions were determined as follows:the optimum ball size for +6.0mm material of 100mm,the optimum ball size for-6.0+2.0mm material of 80mm and the optimum ball diameter for-2.0mm material of 70mm.Optimum media ratio was 90mm of 34.62%,70mm of 26.92%,60mm of 23.08%,and 40mm of 15.38%.Suitable media charge ratio was 32%,suitable material-ball ratio was 1.0,appropriate rotation speed rate was 80%and suitable grinding concentration was 78%.Beneficiation process investigation and the bond work index simulation results showed that one-stage ball mill in Qidashan worked in the low level:media charge ratio of 28%?30%,mill processing capacity of 310?320t/h with mill utilization coefficient of 1.66 t/(m3·h).If only increase the filling charge ratio up to 32%?33%,table processing capacity can reach 353.02?359.36t/h.If optimize media size,rotation speed rate with 32%?33%filling charge ratio in the grinding process,the processing capacity of ? 5.49×8.83m ball mill can achieve 372.92?379.61t/h.According to the results of laboratory research,the ball mill process optimization scheme was put forward as follows:1)Improve media charge ratio up to 32%,mainly achieving by adding hollow shaft bushing and material retaining ring and and installing magnetic sealing device in the bending pipe for feed.2)Increase the mill rotation speed rate up to 80%,namely rotation speed of 14.5r/min,achieving by modifying the small gear.3)Increase the adding ball diameter up to 100mm,strengthening the grinding effect of coarse particles.Industrial test results showed that when adding filling rate of the ball mill from 28%?30%up to 32%?33%,the grinding-classification indexes of Qidashan iron ore beneficiation plant improved slightly and processing capacity of ? 5.49 x 8.83 m ball mill could rise from 310?320 t/h up to approximately 350 t/h.Research results of this paper revealed the reason why mill processing capacity of? 5.49x8.83m ball mill of Qidashan iron ore beneficiation plant was low.The bond work index simulation was used to calculate the motor power consumption and processing capacity of the processing capacity of ? 5.49×8.83m ball mill.On the basis,effects of different grinding conditions on the Qidashan ore iron ore were researched in detail,and grinding-classification optimization scheme was put forward in view of the above research results.Finally,industrial test was carried out,achieving a satisfactory performance.The research results provides the theoretical guidance for improving processing capacity of large-scale ball mills in mineral beneficiation plant.