Experimental Study on the Preparation of Paste Filling Materials from Coal-Based Solid Wastes

Area of Science:

• Materials Science
• Civil Engineering
• Waste Management

Background:

• Coal-based solid wastes, including fly ash, desulfurized gypsum, and carbide slag, present disposal challenges.
• Developing cost-effective and sustainable filling materials for coal mines is crucial for the mining industry.

Purpose of the Study:

• To develop a novel composite cementitious material using coal-based solid wastes to reduce filling material costs.
• To evaluate the performance of the developed material for coal mine filling applications.

Main Methods:

• Characterization of physical and chemical properties of raw materials (fly ash, desulfurized gypsum, carbide slag, cement, water).
• Systematic proportioning tests using the single-variable method to determine optimal formulation.
• Evaluation of slurry workability (fluidity, bleeding rate) and hardened sample properties (compressive strength, chemically bound water content).

Main Results:

• Optimal formulation: fly ash:desulfurized gypsum ratio of 70:30, 20% carbide slag, 15% cement, and a water-cement ratio of 0.65.
• Achieved performance: fluidity 180-220 mm, bleeding rate <5% within 6 hours, and 28-day compressive strength of 17.69 MPa.
• The composite material meets the requirements for mine filling with good fluidity and high hardened strength.

Conclusions:

• The developed composite cementitious material effectively utilizes coal-based solid wastes.
• The material demonstrates excellent workability and mechanical properties suitable for coal mine filling.
• This innovation offers a cost-effective and sustainable solution for coal mine backfilling.