Effect Of Fine Content On Mechanical Properties Of Tailings

With the advancement of mineral processing technology and the decrease of ore taste,the tailings produced by metal mines are getting finer and finer,and the proportion of fines in the tailings is gradually increasing.Therefore,it is particularly urgent and necessary to study the influence of fine grain content on the rock and soil properties of tailings.In this paper,a series of laboratory tests are carried out on metal tailings with a fine content of 0%,10%,30%,60%and 80%,and the effects of fine content on the particle gradation,mineral composition and lateral pressure coefficient of the metal tailings are analyzed.,The influence of critical state parameterrs,static liquefaction and residual strength,combined with the electron probe test and the minimum void ratio,arialyzed the influence of the fine content on the rock and soil characteristics of the tailings.The key results obtained are shown as follows:(1)Based on particle analysis experiments and fractal theory,it is found that with the increase of fine particle content,tailings transition from poor gradation to good gradation.The minimum porosity of tailings shows a trend of decreasing first and then increasing,while the change of mineral composition is very small,so it is difficult to explain the influence of fine particle content on the physical and mechanical properties of tailings.(2)The lateral pressure coefficients of the five kinds of fine content tailings all decrease with the increase of dry density,but there was no good correlation between the lateral pressure coefficient and the fine content.Combined with the test data,it is found that the Jaky simplified formula obviously overestimates the lateral pressure coeficient of tailings.(3)In the e-lgp’ space,when the fine content is less than 30%,the increase in the fine content causes the critical state line to slowly move downwards,and the slope gradually decreases.When the fine content exceeds 30%,the critical state line rapidly Moving up,the slope increases drastically.Although the critical stress ratio increases first and then decreases with the increase in the content of fine particles,this change is very small.(4)When the content of fine particles is less than 30%,the increase of the content of fine particles is beneficial to the increase of pore water pressure,and when the content of fine particles exceeds 30%,the increase of the content of fine particles will inhibit the increase of pore water pressure.Therefore,with the increase of fine particle content,the liquefaction resistance of tailings first decreases and then increases.That is,before the fine content exceeds the critical content of the fine,the increase of the fine content will promote the static liquefaction of the tailings.And when the content of fine particles exceeds the threshold,the increase in the content of fine particles will inhibit the occurrence of liquefaction.(5)With the increase of vertical stress,shear rate and initial dry density,the peak strength and residual strength of the four kinds of fine content tailings all show an increasing trend;while with the increase of fine content,the residual strength of tailings gradually decreases.small.