| Coal mine in our country mainly uses well foreman wall roof cavingmining method, resulting in strata collapse, land subsidence, groundwaterresources and ecological destruction, as well as a large number of coal pillarunderground indwelling serious problems, especially the "three under"(underbuildings, railways, water bodies) pressure coal is increasing. Filling miningmethod is a effective method to solve the above problems, the fly ash pastefilling material that make of fly ash discharged by the power plant, coalganguedischarged by coal mine and cement,not only has the advantages of low cost andrich sources,but also solved the enviroment pollution and land pccupied problemcaused by a large number of coalgangue and flyash emissions. However, the flyash paste filling material exists the presence of fever phenomenen, adsorption ofgoaf gas, heavy metalsand radioactive harm security problem in the fillingprocess, and this problems still lack of systematic experimental study in ourcountry at present.This paper get the advantage ratio flyash paste filling material based on theraw material characteristic experiment of flyash and coalgangue and proportioning optimization experiment, tested and analysised the characteristicof filling material hydration heat and filling material gas adsorption,summarized and analyzed the environmental pollution and the harm to thehuman body of fly ash and coal gangue.Get the following conclusions:1) Tested and analysised the particle size, mineral compositon, chemicalcomposition and microstructure of fly ash and coalgangue, getting theconclusions that the tested fly ash is off garde because of its low calcium andlow activity, the tested coal gangue is a kind of clay rock, the combition of thistwo kinds of material can be used for preparation of fly ash filling material;according all orthogonal material proportioning test, selected cement: Fly Ash:coalgangue=1:3:5, solid mass fraction of78%or80%, and add the appropriateamount of activator and additive ratio is the advantage ratio of fly ash pastefilling material.2) Tested the characteristic of filling material hydration heat with TAM Airisothermal microcalorimeter. Tested and analysised the hydration heat andhydration heat flow of different proportions filling materials, the heat flow of flyash paste-filling material obviously shows six phases of initiation, induction,acceleration, quickly deceleration,slow deceleration and steady;With theincorporation and the content increases of fly ash and coal gangue, the durationof induction and acceleration phases are prolonged and the heat flow andhydration heat are reduced; Within the experiment range, the influence ofwater-binder ratio on the heat flow is not obvious, and the additive quicken the heat flow of induction phase. Based on the test results and without consideringthe conditions of heat exchange with the outside world, after7days,thetemperature increases of filling body of pure cement, cement:fly ash=1:3+additives and cement: Fly:gangue=1:3:5+additive are69℃,22.9℃and10℃.3) Tested the characteristic of filling material gas adsorption with3H-2000PHD series automatic high pressure gas sorption analyzer. Tested thegas adsorption capacity of filling materials, confirmed the filling material in thecourse of the hydration has gas adsorption properties; this adsorptioncharacteristics of in the first5days curing time is most obvious, after5days theability of gas adsorption saturated gradually;within2Mpa gas confining pressurerange, the adsorption capacity of filling body almost shows linear growth lawwith the increase of gas confining pressure.The gas adsorption of1:3:5+X ratiospecimen was1.2754ml·g-1under2Mpa gas confining pressure after14dayscuring time; the gas adsorption of1:4:5+X ratio specimen was1.3048ml·g-1under2Mpa gas confining pressure after14days curing time. Iimproving thecontentis of fly ash can increase the gas adsorption amount of filling materialswithin5days, but after14days it would restrict the gas adsorption capacity.4) Summarized and analyzed the environmental pollution and the harm tothe human body of fly ash and coal gangue.Fly ash and coal gangue containslarge amounts of natural radioactive elements, heavy metals and other harmfultrace elements, this harmful substances, including copper, zinc, lead, cadmium, chromium, nickel, cobalt, arsenic and mercury and other toxic trace elements,will cause pollution of air, soil and water through weathering and percolationeffects, and will indirectly affect the human body causing injury and seriousillness through the percolation of soil and bioaccumulation. Fly ash and coalgangue contains natural radioactive elements including238U,232Th,226Ra and40K, they are not only a direct result of radiation damage to plants, animals andhumans, but also by percolation into groundwater and ultimately affect humanhealth. |
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