Development On Low Cost Mine Filling Cementitious Material And Study On Its Pipeline Transportation Characteristics

Backfill mining is the most popular mining method at home and abroad,cement is the most commonly used cementitious material in mine filling for decades.However,its large consumption and huge cost is a major problem in the field of mine filling.Taking one of the lead-zinc mines in South China as an example,the total cost of the mining accounts for about1/2 of the total mining cost per year,and the cost of filling material reaches to 199 yuan per cubic meters.Slag is one of the industrial wastes discharged from the smelting process of irons and steels.The emission of the slag is huge in China.Slags occupy a lot of land resources and cause dust pollution.The disposal of the slag is one of the major expense for the iron and steel enterprises.However,the slag has excellent potential activity.Based on the urgent needs of reducing costs of the cementitious materials and utilization of industrial waste resources,it is very important to carry out research on mine filling cementitious materials in which slag is the main raw.This article is based on a research of a new type of filling material which is used for a lead-zince mine in South China.On the basis of previous research results of the research group,a new low cost cementitious material has been obtained through orthogonal test and range analysis.The best combination of this material is slag 53%,phosphogypsum 22%,cement 15%,quicklime 5%,NaOH3% and compound additive 2%.The strength and pipeline transportation of this new cementious material is carried out through field investigation,laboratory test,theoretical analysis,numerical simulation and industrial application test.The main contents and conclusions of this paper are as follows:(1)Micro analysis methods have been taken to analyze the material composition,interface micro structure,product structure and quantity of raw material and graded tailings,by using X ray fluorescence spectrometer(XRF),X ray diffractometer(XRD),laser particle size analyzer.We do research to ditermine to determine the optimal formula of the new cementitious material.We also study the mechanism of the gelation process of this new cementitious material.(2)After the strength test and microscopic analysis,it was founded that,the strength of the filling body formed by the filling slurry of the new cementitious material and the filling slurry of cement were both affected more by the cement sand ratio than the concentration.The reason why the strength of the new cementitious material filling slurry is better than that of the cement filling slurry is that the ettringite crystals are produced faster and more in the new cementitious material filling slurry.A large number of ettringite acicular crystals are intertwined,and are gelled lap with C-S-H,making the slurry stronger and gelation process faster.(3)Tests of the fluidity,segregation degree,bleeding rate,yield stress,viscosity strength of the filling slurry have been carried out in this article.Through comprehensive comparative analysis,it can be concluded that when using graded tailings as aggregate,the filling slurry with a 1:4 cement sand ratio and 78% concentration can be chosen to replace the materials used in the Lead-zinc Mine with a 1:3 cement sand ratio and 75% concentration,and the filling slurry with a 1:6 cement sand ratio and 78% concentration can be chosen to replace the materials used in the Lead-zinc Mine with a 1:5 cement sand ratio and 75% concentration.When the liquidity of the two materials both meet the requirements,the bleeding rate,strength of new cementitious material of the new material filling slurry are both better than those of the cement filling slurry.(4)We use the ANSYS Fluent numerical simulation to calculate and compare the new cementing material filling slurry with cement filling slurry and get the similar rule of pipeline pressure and velocity variation.Through the control variable method,the influence of different slurry concentration,pipe diameter and filling double line on slurry pipeline transportation are studied under certain conditions and the conclusion is obtained: With the increase of slurry concentration,the flow velocity of the slurry in the tube rises slightly and the value of pipe pressure loss per meter increases greatly.With the increase of the inner diameter of the pipe,the flow velocity of the slurry in the pipe is reduced and the pipe pressure loss per meter is reduced and the changes tend to be linear.With the increase of the filling times line of the pipe filling,the flow velocity of the slurry in the pipe is gradually reduced,but the amplitude is very small,while the pipe pressure loss per meter of the slurry increases greatly.(5)In field experiments of industrial production,the conveying condition of the slurry in the pipeline is good,downhole bleeding of the new cementitious material was less than that of the cement filling slurry,and it reached the final setting in 6 hours that people can stand up on it;Maintaining the samples in the surface and underground to the corresponding age,then testing the samples by compressive strength,the results showed that the industrial test samples can both meet the filling strength of the Mine Design requirements,and the underground-sample with higher strength.(6)Making the economic comparison and analysis of the new cementitious material andcement filled filling slurry,the results show that the cost of filling slurry prepared by new cementitious materials is 6.2926 million yuan lower when the fluidity is similar and the strength is better.