Experimental Study On Fractal Dimension Relationship Of Ore Crushing Materials

As an important means of rational utilization of low-grade minerals,beneficiation has something to do with improving flotation quality and efficiency,such as grinding mode,grinding fineness and flotation reagents.But the fractal theory has been proved to be able to quantitatively characterize the particle size distribution characteristics and the shape complexity of single particle image.The author combines the fractal theory with the traditional mineral processing theory to change the familiar qualitative analysis into quantitative characterization.In this paper,magnesite from Dandong,Liaoning and galena from Huize,Yunnan are selected as raw materials,By comparing the particle size characteristics of ore under two ways of ball milling and vertical roller milling,it is found that the grinding products of vertical roller mill are higher than those of ball mill in the content of "intermediate particle grade which is conducive to flotation,Through flotation test,it is found that the concentrate yield of vertical roller mill is higher than that of ball mill for two kinds of minerals,Through particle image analysis and fractal dimension calculation of surface and line,it is found that the fractal dimension of surface and line of grinding products of vertical roller mill is lower than that of grinding products of ball mill,which shows that the complexity of the contour curve of the grain image produced by the vertical roller is relatively small.The results show that for magnesite,when the grinding fineness is-0.074mm,the content is 81.6%,and the volume fractal dimension reaches the maximum value of D3=2.4625,the flotation effect is the best.Similarly,for galena,when the grinding fineness is-0.074mm and the content is 88.3%,the volume fractal dimension also reaches the maximum value D3=2.4127,at this time,the flotation effect is the best;it shows that there is some internal relationship between the maximum volume fractal dimension and the flotation effect.In this paper,two new digital characteristics,fractal mathematical expectation and fractal variance,are defined to describe the particle size distribution of grinding products with discrete random variables.Within the range of existing test results of magnesite and galena,the volume fractal dimension D3 is negatively correlated with the fractal mathematical expectation EF(?)and the fractal variance DF(?).Its meaning is that when the characteristic particle size is given,the smaller the volume fractal dimension is,the larger the fractal mathematical expectation and fractal variance are,that is,the larger the average particle size is,the more dispersed the distribution is;on the contrary,the larger the volume fractal dimension is,the smaller the fractal mathematical expectation and fractal variance are,that is,the smaller the average particle size is,the more concentrated the distribution is.The maximum volume fractal dimension,the minimum fractal mathematical expectation and the minimum fractal variance correspond to the most suitable grinding fineness for flotationThe fractal dimensions of body surface and line of grinding products were measured by experiments,It shows that the average relative error of fractal dimension relationship of volume and line is 0.485%,and the average relative error of fractal dimension relationship of volume,surface and line is 2.87%.The experimental results show that the fractal dimension of volume,surface and line is reasonable and credible.