Study of Improvement of Energy Efficiency of Grinding Operation

Research Project

Project/Area Number	59850102
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	資源開発工学
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	YASHIMA SABURO Research Institute of Mineral Dressing and Metallurgy, 選鉱製錬研究所, 教授 (90006966)
Co-Investigator(Kenkyū-buntansha)	HASHIMOTO HITOSHI Research Institute of Mineral Dressing and Metallurgy, 選鉱製錬研究所, 助手 (90156290)
Project Period (FY)	1984 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥5,900,000 (Direct Cost: ¥5,900,000) Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000) Fiscal Year 1985: ¥1,000,000 (Direct Cost: ¥1,000,000) Fiscal Year 1984: ¥3,900,000 (Direct Cost: ¥3,900,000)
Keywords	Grinding / Grinding Efficiency / Simulation Model of Ball Milling / Motion of Grinding Media / Single Particle Crushing / 粉砕機構 / 粉砕媒体の運動エネルギー
Research Abstract	Grinding is an important unit operation in almost all industries. However, the design of grinding machines and processes and the selection of operational conditions have not been done on a reasonable basis. For instance, a ball mill is presumed to have very complicated grinding mechanism because of the complicated motion of grinding media and significant effects of the loading rate on the fracture behavior of single particles. In this investigation, the grinding process in a ball mill, which is a representative grinding machine, was simulated by using a simple model of the grinding process from the viewpoint of single particle crushing in order to elucidate the grinding mechanism. Grinding tests were also carried out to verify the validity of the simulation model. The motion of the grinding media in the ball mill was, therefore, estimated by measuring the impact force of the media by means of load sensors buried in mill shell. As a result of the measurement, the ball charge fraction and lifters had significant effects on the motion of the media and the conversion efficiency of input energy into kinetic energy of the media. Results of the simulation for effects of some operational conditions were, however, not in good agreement with those of the grinding tests, especially for the effects of the ball charge and lifters. On the basis of this fact, the breakage of particles by the impact force of the media is presumed to be not a dominant grinding mechanism in the ball mill. It is probably that the breakage by the shearing force, what is called the frictional crushing, is dominant.