Preparation and Performance Test for Coal Mine Filling Material of Furnace Bottom Ash - Coal Gangue

In order to realize the resource utilization of solid waste and reduce the cost of filling and mining, the coal mine filling materials were prepared with furnace bottom ash and coal gangue as raw materials. The effects of particle grading, mass fraction of filling slurry and quality fraction of cementing material on the properties of filling materials were studied. The hydration products of the filling materials were analyzed by means of X-ray diffraction, scanning electron microscope and energy spectrum analysis. The results show that when the maximum grain size of coal gangue is 4.75 mm, the mass ratio of coal gangue to furnace bottom ash is 1:1, the mass fraction of filling slurry is 77%, and the quality fraction of cementing material is 20%, all the properties of filling materials can meet the requirements of filling mining. With the increase of curing age, active silica in filling materials is consumed in hydration reaction, while the production of ettringite, hydrated calcium chloroaluminate, hydrated calcium silicate and calcium silicate aluminate hydrate gel are increased. In the hydration products of filling materials, the flake hydrated calcium chloroaluminate crystal grows alternately with ettringite and are wrapped in hydrated calcium silicate gel to form a dense whole, which improves the uniaxial compressive strength of the fillings.