Study On Segregation Mechanism And Control Technology Of Coarse Aggregate Filling Slurry In Jinchuan

The vertical uneven distribution of coarse aggregate filling slurry concentration is the root cause of slurry segregation,which reduces the strength of cementation body and the overall stability of filling body,and brings hidden danger to the safe and efficient production of Jinchuan mine.This paper is based on Jinchuan company major scientific research project "Research on segregation mechanism and control technology of coarse aggregate filling slurry”,taking filling mining in Dragon Head Mine as engineering background,it studies and reveals the mechanism of segregation concentration distribution of coarse aggregate slurry in slicing.By means of mixing fine aggregate and combining with the development and application of new cementing materials,this paper explores the control technology and optimization of segregation of coarse aggregate slurry for downward slicing filling mining in Jinchuan Mine.The scheme lays a foundation for the utilization of coarse aggregate such as waste rock and bar grinding,thereby reducing filling cost and improving economic,environmental and social benefits of filling mining.By theoretical analysis,laboratory test and industrial filling test,the main conclusions and achievements are as the followings:(1)Based on diffusion theory,the vertical distribution formula of coarse aggregate filling slurry concentration was deduced by combining the factors of particle size,particle density,slurry density,yield stress and particle shape.The results show that the vertical distribution of coarse aggregate slurry with concentration less than 80%enhances with slurry concentration increasing;when the concentration is more than 80%,the distance between concentration distribution curves increases,and the concentration distribution in different positions along the vertical direction increases greatly.(2)Research results based on XRD,scanning electron microscopy and TG-DSC show that the early(3d)strength of filling body is due to AFt,the addition of appropriate amount of gypsum promotes the formation of AFt and consumes part of Ca(OH)2,as the age progresses,the later(28d)strength develops better due to the existence of gypsum.The weight loss rate of hydrated products of clinker gypsum was 1.03%and 5.04%for T6,3.93%and 6.38%for T7,3.85%and 8.29%for T9,respectively.(3)Based on the study of the influence of activator ratio on slag-based cementitious materials,it is revealed that the filling slurry is prepared with cementitious materials that made of cement clinker 12%,desulfurization gypsum 3%,Jiuquan steel's slag 85%.The average compressive strength of 3,7 and 28 days are 2.6 MPa,5.5 MPa and 9.3 MPa,which are 1.73,2.20 and 1.86 times of designed strength of the cemented filling body in Jinchuan Nickel Mine.(4)The rheological properties of filling slurries made of two cementitious materials show that the rheological curves of trend in the same way,only in different time duration.When the concentration is less than 80%,the shear stress drop time of SC-prepared slurry is later than CC.When the concentration is 80%and 82%,the concentration distribution curve of SC-prepared filling slurry is higher than CC.The expansion degree of SC slurry is greater than CC slurry,and the fluidity of SC slurry is better than CC slurry.(5)The filling characteristics of two kinds of aggregate,waste rock-bar grinding-fly ash and waste rock-bar grinding-limestone powder,were studied,The content of fly ash is 25%-30%,the mixed aggregate system reaches the best dense state,the compressive strength of cemented backfill is the largest,and the slump of slurry reaches the maximum value of 27.2cm.When the content of limestone powder is more than 30%,the strength of filling body is larger,and the bleeding rate of slurry is no longer changed.(6)The genetic tree based on dynamic adaptive probability and fitness competition exchange mode is used to establish the model of filling strength and slurry working characteristics.The results show that the calculated values are basically in agreement with the experimental values,and the error range is less than 5%.(7)Based on the intelligent optimization method of filling slurry ratio,the optimum content of limestone powder is 12.3%,the compressive strength of filling body for 3d,7d and 28d is 1.9MPa,2.51 MPa and 6.8 MPa,the slurry expansion and bleeding rate are 73 cm and 6.4%.(8)The L-tube test shows that the fluidity of slurry can be improved by adding fly ash as fine aggregate.The slurry concentration of 78%? 80%in the original industrial production is increased to 80%? 82%,and the yield stress is significantly reduced.(9)The field industrial test shows that the yield stress of the two kinds of filling slurry is reduced by 20.2%and 37.4%respectively,the viscosity coefficient is increased by 10.9%and 16.7%,the flow rate is increased from 104m31h to 113m3/h,and the resistance along the way of the two kinds of filling slurry is increased by 8.4%and 6.9%.