Properties and hydration characteristics of mine cemented paste backfill material containing secondary smelting water-granulated nickel slag

Abstract

In order to improve the level of solid waste comprehensive utilization and reduce the cost of filling raw materials for mining, a study is carried out on the preparation of cementing agents (CA) for underground mine filling using secondary smelting water-granulated nickel slag (SWNS) as the main raw material. The mechanical properties test, X-ray diffraction (XRD), flourier transform-infrared spectroscopy (FT-IR), thermogravimetric/differential scanning calorimeter (DSC-TG), scanning electron microscope (SEM) and other test methods were used to study the working performance and mechanical properties of the cemented paste backfill (CPB) material, and the types of hydration products, micro-morphology and hydration characteristics of CA of SWNS for CPB material were analyzed. The results show that when the ratio of CA used for CPB material is SWNS:cement clink (CC):Na2SO4:flue gas desulphurization gypsum (FGDG):carbide slag (CS) = 85:2:3:5:5, the binder content on dry basis of tailings (CA/iron ore tailings (IOT)) 1:4, the slurry concentration 82%, and the addition of 0.156% PC water-reducer, the static compressive strength of CPB material 28 days is 7.94 MPa, which is 57% higher under dynamic loading conditions than that under static loading, the tensile strength is increased by 72%, and the shear strength is increased by 127%, which meets the strength requirements of CPB materials used in underground mines. CA of SWNS is a CPB material containing glass phase and crystalline materials. Under the action of various activators, it can participate in the hydration reaction, and the main hydration products are ettringite (AFt) and hydrated aluminosilicate gel material (C–M–S–H) containing Ca2+ and Mg2+; (C–M–S–H) is the main source of strength in the later stage of CPB material.