Experimental Study On Preparation And Properties Of Coal Gangue Based Microbial Mineralized Filling Materials

During the development and utilization of coal resources,a large number of solid wastes are discharged,including coal gangue and fly ash,etc.,while the underground filling mining technology can realize the effective disposal of coal-based solid wastes.As for the cemented filling material,it is usually necessary to add a certain proportion of Portland cement as the cementing material during the preparation of the material,so that the cemented filling material has the bearing strength.However,the addition of cement not only increases the cost of mine filling,but also has a certain impact on the ecological environment.Therefore,this thesis puts forward the idea of microbial mineralized coal gangue based filling material,in order to develop a kind of low price,environmentally friendly cementable material.USES the field investigation and theoretical analysis,laboratory test and data processing methods,such as pap bacillus in coal gangue and fly ash was studied the growth pattern training system,and the active factors,established the microbial mineralization coal gangue filling material preparation,test and analysis the microbial mineralization packing material conveying and mechanical properties,The composition change and microstructure evolution of microbial mineralized filling materials were revealed.The main achievements are as follows:(1)The types,preparation technology and characteristics of backfill materials in underground coal mine are summarized,the chemical reaction process of microbialinduced calcium carbonate precipitation and the mineralization of coal gangue particles are analyzed,the influencing factors of microbial-induced calcium carbonate formation are expounded,and the basic ideas of microbial-mineralized coal gangue based backfill materials are put forward.(2)Tested coal gangue,fly ash and other chemical and physical properties of solid waste materials,studies the pap bacillus in the growth rule of coal gangue and fly ash mixture,and analyses the influence of p H,temperature and quantity of mineralization bacteria activity,the influence of mineralization bacteria is given the best culture conditions of microbial mineralization is established the preparation method of the coal gangue filling material.(3)The properties of microbial mineralized filling materials were tested,and the mineralization fluid concentration during the preparation of packing material,urea concentration and mass concentration of filling material conveying and the influence law of mechanical properties,analyzed the different curing conditions,such as temperature and time characteristics of compressive strength of filling material,reveal the microbial mineralization evolvement filling material performance.(4)The composition changes of microbial mineralized filling materials were tested,and it was found that there were more calcite type calcium carbonate in the materials and the mineralization promoted the hydration reaction in the materials.The interaction between coal gangue,fly ash and calcium carbonate in the mineralized backfill material was studied,and the microstructure evolution characteristics of the microbial mineralized backfill material were analyzed.There are 41 figures,13 tables and 104 references in this thesis.