Experimental study on new filling cementing material using water-hardening nickel slag tailings of Jinchuan Mine

By the end of 2012, the stockpiled quantity of nickel copper slag of Jinchuan Mine in China was 3.3×10⁷ t, and 2.5×10⁶ t is yielded every year. The quantity of discharging waste nickel slag every year is 1.25×10⁶ t when the iron is extracted from the water-hardening nickel slag. Using metallurgical waste to develope a new type of filling cementing agent for mines can realize recycling use of waste and may reduce the cost of filling mining. Based on the characters of the water-hardening nickel slag of Jinchuan Mine, both the mechanical activation and chemical activation are implemented to obtain a new type of filling cementing agent. Based on the mechanical activation, the best specific surface areas of nickel slag tailings, desulfurization gypsum, calcium carbide slag and cement clinker are respectively 620, 200, 200 and 300 m²/kg. The chemical activation may use desulfurization gypsum and calcium carbide slag as the main activators, and sodium sulfate and cement clinker as the auxiliary ones. When the mixing amount of nickel slag tailings is 85%, the optimal mixing amounts of the compound activating dosage are respectively 5%, 5%, 3% and 2%. If the PC high efficiency water reducing agent of 0.156% is added, the strengths of filling body for 7 and 28 d will be respectively 2.9 and 6.3 MPa when the cement-sand ratio is 1∶4 and the concentration of the slurry is 79%, which can meet the strength of filling body for safe mining in Jinchuan Mine. It is seen that the proposed new type of filling cementing agent can replace cement for filling mining in Jinchuan Mine.