The Development And Research On High-efficient Cylindrical Classifying Equipment Of Mineral Particles

The process of particle classification is widely used in mining,metallurgy,environmental,chemical industry,and other fields,which operational precision and efficiency is an important parameter of regulation.In the mining field,classification(screening)equipment is usually used in series with grinding equipment to form a grinding----classification closed circuit process.In general,Hydraulic classification equipment such as hydrocyclone and spiral classifier have problems such as inaccurate classification accuracy,and screen classification equipment such as high-frequency fine screen and linear vibrating screen have problems such as serious screen surface wear and easy to plug screen hole.In this paper,the author invents a cylindrical high-efficient mineral particle classification equipment(Eddying Classification Column),which combines the advantages of screen classification and hydraulic classification.It has the capability to control the size of particle classification with cylindrical screen and to improve the efficiency of the particle passing through screen with pulsed fluid by the blade,hence the precision and efficiency of particle classification are greatly improved.The equipment developed by the author mainly consists of power unit,central rotating shaft,blade,cylindrical cylinder,cylindrical screen,coarse and fine grain ore drainage pipe,supplementary water pipe and ore feed pipe,etc.Moreover,the motor is connected with a frequency modulator,which is used to adjust the rotation speed of the central shaft and the blade is welded and fixed on the central rotation axis.Each layer of the blade is composed of three evenly distributed blades on the circumference and the cylindrical column is made of transparent material.Firstly,in this paper,the author studies the influence factors of vortex Eddying Classification Column efficiency and its coupling relationship.Static test shows that particle classification could be achieved with balance in a short time and particle classification has been basically completed in five seconds,then the improvement of particle classification efficiency is very small.Besides,static test shows that the efficiency of mineral particle classification decreases when the adding speed of slurry increases;It also shows that classification efficiency increases slightly and tends to a stable state when blade speed is greater than or equal to 900rpm.And the continuous classification test shows that classification efficiency does not change with classification concentration when ore adding speed is relatively small.With the increase of ore adding speed,the classification efficiency decreases rapidly,but it still has a high classification efficiency.For example,in the continuous classification test,when the pulp concentration is 30%,the maximum value of E_{(quantity 0.25mm)}is 88.37%,and the minimum value is 82.04%.Secondly,the author studies the trend,shape,turbulent region of water and the motion state of mineral particle in Eddying Classification Column by high-speed camera observation experiments.It shows that blade rotation speed increases,thrust is larger and the faster the flow,the more turbulent it is.The role of azimuth Angle?of blades is to push the fluid outward and upward.The greater?is,the more perpendicular the direction of fluid movement is to the screen.However,the greater?is,the greater the distance between blade tip and screen is,the smaller the suction space on the back of blades is,and the weaker the suction.The role of blade azimuth?is to promote the fluid forward and upward movement,the greater the?is,the greater the driving effect of the fluid is,and the greater the suction force on the back is.Finally,according to classification experiment results and observation results of high-speed camera,the author puts forward a hypothesis about the classification theory of Eddying Classification Column:in the circumferential direction of blade rotation,the mechanical energy of blade rotation will be transferred to pulp,and blade(positive)push ahead pulp movement forward,while the rear of the blade has a back suction effect on the pulp.Because this push-suction action allows the pulp particles to shuttle back and forth between the inside and outside of the screen,which can promote and strengthen the loosening,dialysis and penetration of particles,thus the equipment has a higher classification efficiency.Through the above research,the author optimizes the structure of Eddying Classification Column and confirms its favorable conditions in classification.Above all,the author puts forward a hypothesis about the classification theory of it,which can lay a foundation for the classification research of the equipment in the field of mineral processing.