Mechanism Analysis And Energy Consumption Experiment Of Pre - Mill Mill

Vertical pre-mill is a new kind of mining equipment mainly designed to improve the reduction of the milling efficiency due to the feed’s particle size of the ball mill is too big. Its design concept is "with crushing instead of grinding" and "more crushing less grinding". The crushing medium in high speed crush the materials in the crushing cavity, and at the discharge port, the rotating rotary table in high speed crush the material in the form of shearing. The application of vertical pre-mill can change the most mine’s existing grinding process. After coarse crushing, crushing and fine crushing, the ore was put into the vertical pre-mill machine grinded to-10mm, even-5mm and then was put into the ball mill for grinding, so as to improve the grinding efficiency and reduce the energy consumption of grinding system.In this paper with new type of vertical pre-mill as the research object, using the method of theoretical analysis, experimental research and optimization design of the parameters through the combination of some basic research on vertical pre mill, The research content mainly includes the vertical pre-mill mechanism analysis, single exploration of the motion law of pre grinding medium and vertical pre-mill work and the experimental study on the mill for the optimization of effective power. Main results are as follows:(1) According to the structure and working principle’s analysis of vertical pre-mill, the vertical pre-mill broken form consists of impact crushing, shearing crushing, attrition crushing, grinding and so on, and the impact crushing is the main form.(2) The author analyzed the stress and movement process of the grinding medium in vertical pre-mill based on the analysis method of particle kinematics and divided the movement of the media in the vertical pre-mill into three stages:first, preliminary grinding medium’s accelerated motion with rotary turntable; second, preliminary grinding medium’s upward movement in the spherical cavity after preliminary grinding medium breaking away from the rotary turntable; third, the shock movement of the preliminary grinding medium. The author derived the motion expression of each stage, and found out the relationship between the medium size, the structure of the crushing cavity, ejecting wheel diameter and the movement of the medium, the motion parameters of the ejecting wheel, providing the according for the structure design and motion parameter design.(3) Orthogonal experimental method to select pre-mill upper and lower crushing chamber rotary speed, medium filling volume, the ratio of the size of the media filled the four investigated factors, according to preliminary experiment condition, select the five experimental levels, vertical mill crushing process pre-test, analysis of experimental results obtained, the minimum average particle size of nesting1.16mm, maximum average particle size of1.76mm nesting, the discharge size meet the design requirements;And the test results are range analysis:the discharge size, motor power consumption both for the comprehensive evaluation index cases to get the optimal experiment scheme is:the upper crushing cavity rotary speed of9m/s, lower crushing cavity rotary speed of9m/s, medium filling rate is25%, size medium filling ratio of75%;(4) Employing the data fitting method, the power consumption of the experimental data for further analysis, through the parameter optimization design to meet the pre-mill case of nesting size, power consumption the most hours of each parameter values for the upper crushing chamber rotary speed9.2m/s, the lower the crushing chamber rotary speed9.6m/s, media fills rate of23%, the size of the media filling ratio69%;Adopts the optimized results of the experiment, and compared with before optimization data, the whole discharge size fell by16%after optimization, Motor power consumption reduced by21.4%.the optimization effect is obvious.In summary, the vertical pre-mill has good application prospect, and this research will lay the foundation for the further theoretical research and application of vertical pre-mill.