Study On Transportation And Mechanical Properties Optimization Of Sand-based Cemented Filling Materials

As the core of cemented and filling mining technology,filling materials determine the filling cost and filling quality,which affects the implementation and development of filling mining technology.This paper aims at the problem that filling gangue in some mining areas in China has few sources and conventional filling mining technology is difficult to implement.The Yellow River sand,which is widely distributed around the mining area and cheap in price,is used as the filling aggregate,and part of cement and fly ash are added as the sand base consolidation filling material.The transport and mechanical performance indexes of the sand base cemented filling material are tested,and the performance defects and causes of the sand base consolidation filling material are analyzed.Optimized the shortcomings of sand-based cemented filling materials and a new type of sand-base cemented filling material for coal mine filling mining is obtained.The strength evolution and hydration mechanism of the material were also discussed.The research results obtained in the paper are as follows:(1)The selection requirements of coal mine cemented filling materials are summarized,and the transport and mechanical properties of coal mine cemented filling materials are analyzed.Based on the physical and chemical characteristics of raw materials such as Yellow River sand,fly ash and cement,the feasibility of Yellow River sand and fly ash as raw materials for cementing and filling was analyzed.(2)Based on the structure tested by orthogonal test,the engineering performance defects and their causes of the sand-base cemented filling materials composed of Yellow River sand,fly ash and cement are analyzed.The main and secondary factors affecting transport and mechanical properties of sand-base cemented filling materials were studied.(3)Using water reducer and quicklime as optimization material,The single admixture and mixed admixture test was designed,and the effects of water reducer and quicklime on the engineering properties of sand-base cemented filling materials were studied under the condition of single admixture and mixed admixture.A new type of sand-based cementing filling material was obtained,which determined the optimum dosage of each filling material and analyzed the cost of the filling material.(4)Based on the optimal ratio of sand-base cemented filling materials before and after optimization,the strength characteristics of the two materials were tested and analyzed,and the strength evolution and microstructure characteristics of the new sandbase cemented filling materials were explored.The research results of this paper have obtained a new type of sand-base cemented filling material that meets the requirements of coal mine consolidation and filling mining,expanded the selection range of cemented filling material,provided a new way for coal mine mining in similar areas lacking filling material,and further expanded the applicable scope of filling mining method.