The Experiment Study Of New Double-Ball Grinding Media Applied To Grinding Materials Of Chehe Concentrator

The DACHANG cassiterite polymetallic sulfide ore is known as one of the most important nonferrous metal ores in China, which contains the gangue minerals such as quartz and carbonate, the sulfide minerals such as galena, sphalerite, iron sphalerite, pyrite, pyrrhotite and arsenopyrite, the oxide minerals such as cassiterite.Because of the differences of natural properties and processing methods between cassiterite and sulfide minerals, the less-grinding of cassiterite and the over-grinding of sulfide minerals could easily happen, which can decline the quality of concentrate products and cause the loss of fine cassiterite particles. Therefore, the precision regulation of grinding process and the development of new grinding media can help to solve the problems.This thesis surveyed the second-stage grinding-classification system of CHEHE concentrator firstly. Then, using ball media and doubled-ball media respectively as grinding media, and the feeding of No.6mill in CHEHE concentrator as experimental material, the influences of grinding medium type, grinding time and medium size on all size fractions of the grinding products were investigated. Finally, the grinding dynamics of the two shape types of media were studied. The following conclusions could be summarized.(1)There existed serious over-grinding in the second-stage grinding-classification system of CHEHE concentrator. Cassiterite was ready to be enriched in the return part of the spiral classifier which shows its lower classification efficiency in dealing with cassiterite polymetallic sulfide ore.(2)Because of little change of the medium surface area, the doubled ball media can provide greater impact force than the single ball media, and it has a higher efficiency in grinding coarse particles;(3)There are more intermediate size fractions generated during the grinding process with the doubled ball media than with the single ball media, which means on the one hand the doubled ball media can help to reduce the contents of fine particles, but on the other hand the grinding efficiency of the intermediate size fractions is lower;(4)The doubled ball media can help to reduce the contents of fine particles efficiently, especially in the particle size fraction of-0.038mm;(5)According to the first order grinding dynamics simulation, doubled ball media has higher rate in grinding coarse particles, lower rate in grinding intermediate size fractions, and lower rate in generating fine size fractions. Overall, doubled ball media has a relatively lower degree than single ball media in fitting their grinding behaviours to the first order grinding dynamics, which means the possible change of grinding mechanism and media movement;(6)Under the experimental conditions, the size fraction of-0.63+0.315mm can be considered as the transition fraction, whose grinding rate basically equal to the generation rate.