Experimental Study On The Preparation Of Coal Mine Filling Materials By Using The Yellow River Sand

In this paper,the use of the Yellow River silt to prepare coal mine filling materials is a new type of coal mine filling materials research and development to solve the problem of sediment deposition in the Yellow River reservoir area and the existing coal mine filling material shortage.The Yellow River silt coal mine filling material is prepared by ordinary portland cement,fly ash,the Yellow River silt,water and admixture.In order to satisfy the requirement of pumping,the slurry has good flowability and workability.In order to satisfy the need of continuous operation,the setting time and compressive strength of filling materials meet the design requirements.Therefore,the Yellow River silt coal mine filling material need to meet the following indicators: the slump is 260~280mm,no bleeding,the initial setting time is 2~4h,the final setting time is 6~8h,the compressive strength of not less than 6MPa.Indoor experiment is divided into two parts.The first part is in the absence of additives.In the case,designing test mix proportion and molding test block by two kinds of test methods,the optimization experiment on the best content of raw materials and the orthogonal test.Testing mixture slump,bleeding rate,setting time and mechanical properties,analysis of influence of raw material content on workability and basic mechanics performance of the Yellow River silt coal mine filling material.Determining the optimum mix ratio of the Yellow River silt coal mine filling material is as the basis of the experimental group.Second is in the case of adding additives,through the single factor experiment design method to determine the optimum dosage of water reducing agent,accelerator and activator.Three admixture dosage as variable,orthogonal test design factors and levels of orthogonal table L9(33).According to the matching ratio in the table,we can form a multi set of test blocks.Testing mixture slump,bleeding rate,setting time and mechanical properties,we can analyze the influence of three kinds of admixtures on the workability and basic mechanics performance of the Yellow River silt coal mine filling material.Combined with the actual situation to determine the optimal mix ratio for the test is cement 400 kg/m~3,fly ash 400 kg/m~3,the Yellow River silt 800 kg/m~3,water 400 kg/m~3,water reducing agent 4 kg/m~3,coagulant 8 kg/m~3,activator 8 kg/m~3.In order to realize the Yellow River silt coal mine filling material used in the coal mine goaf,in addition to the need of laboratory research,outdoor simulation tests are needed.On the basis of laboratory mix ratio,the formation test of 0.8 * 0.8 * 0.8 m~3 cube big test block and the field filling test of filling pool were carried out.The experiment shows that the mix ratio of the laboratory can meet the engineering construction requirements,the use of the Yellow River silt to prepare coal mine filling material is feasible.