Experimental Study On Sand Filling Material In Old Empty Area Of Coal Mine

Coal as China's major fossil energy,with the characteristics of large mining.A large number of coal mining left a lot of old goaf,to follow-up production and construction has brought security risks.This paper analyzes the characteristics of coal as the main fossil energy in China,the characteristics of its exploitation and the security risks of the old wasteland caused by the large amount of coal mining.Grouting is an important means to control the old empty area,and grouting material is an important factor affecting the implementation of the old empty area filling scheme,but the existing coal mine empty area filling material can not meet the requirements of the old coal area filling requirements,It is of practical significance to develop a new coal mine empty area filling material.The paper analyzes the characteristics of the selected materials.Among them,the inert material selection of cheap sand,gelling agent used cement and cement powder,additives used FDN water-reducing agent,water from the laboratory tap water.And the reaction principle of cement-cemented sand and cement-cemented sand is analyzed.In order to meet the requirements of payability,diffusion range and stone strength,the evaluation index selected liquidity,water cut rate,initial finishing time and 28d uniaxial compressive strength,and analyzed the range of each index.The test is divided into two steps:the orthogonal test and the regular experiment.The first test is an exploratory test before the regular test.The aim is to find out the feasible ratio range through a wide range of matching,which can provide reference for the next regular experiment.The regularity experiment aims to explore the relationship between the evaluation index and the factors.The results of the test were analyzed,and the actual construction,in the know the pulp of the mobility,water rate,compressive strength requirements,according to the various indicators after the summary of the total map,find the desired pulp Ratio.Compared with the preparation of the slurry and the previous project with the cost of the merits of the pulp.Cement cementing sand as the old coal area filling material,compared with the existing cement cemented fly ash coal mine empty area filling material,the advantage is not big.Compared with the existing cement cemented coal ash,there is a great advantage in the local production of colloidal powder,and the cost is less than that of the existing cement cemented coal ash.Two thirds of the material,considerable economic benefits.