Study On The Clay Content Effect And Soildification Of Industrial Tailings Under Different Hydration Environments

With the continuous development of mining techniques and the further exploitation of tailings,thus producing an enormous amount of industrial tailings with fine particles.This kind of tailings is usually directly discharged into tailings reservoir,resulting in perennial liquid-plastic state of the reservoir surface due to the characteristics of low strength and high-water content,which are of high hidden danger.Clay content,as a part of industrial tailings,has a direct impact on the nature and solidification of it.In addition,because of the unique geographical location of mine,a great quantity of salt is contained in sedimentary strata,forming salt solution.The dual effects of solution and clay content on industrial tailings need to be examined.With industrial tailings in Zhashui area as the study object,basic physics experiment,static triaxial test and unconfined compression test are conducted,exploring the effect of the clay content of industrial tailings on their own under different concentrations of sodium chloride solution,and conducting solidification tests.The results are as follows:(1)The proportion of primary mineral in industrial tailings is high;The particles are smooth and hard because of mechanical grinding.(2)As the clay content in the mixture rises,the permeability coefficient decreases;the compressibility increases first then decreases,and the value of inflection point is 9%.(3)When the clay content is the only influencing factor,its increase will cause the strain curve of industrial tailings to change from a softening type to a hardening type,and the shear strength will first increase slightly and then decrease.The adhesion increases,and the internal friction increases and then decreases.Finally,based on the Duncan-Chang model,a constitutive model of industrial tailings considering the clay content and the confining pressure was established,and the results were remarkable.(4)The overall trend of the strength properties of industrial tailings under the combined effect of Na Cl concentration and clay content is the same as the condition when the clay content acts the sole influencing factor.When the clay content is invariant,the softening degree of the stress-strain curves is aggravated by the low Na Cl concentration,which lowers the shear strength.While the Na CL concentration is high,the experimental results are opposite to the above.(5)Low Na Cl concentration slows down the rate at which the cohesion of industrial tailings increases with increasing clay content,and accelerates the rate at which the internal friction decreases with decreasing clay content.The results are contrary under the condition of high Na Cl concentration,and based on the microstructure of industrial tailings,the corresponding mechanism is explained.(6)The optimal composite ratio for industrial tailings curing is: cement(A): clay content(N): antiseptic wheat straw(C): slag powder(D): molecular water-absorbing(E)= 160:60:2:110:8.And a multiple nonlinear regression model is established to predict the unconfined compressive strength of cured industrial tailings at different curing periods,which is of good fitting effect.