Experimental study of high-flow and low-expansion backfill material

Area of Science:

• Materials Science
• Mining Engineering
• Geotechnical Engineering

Background:

• Difficult slurry pipeline transport and poor roof contact are common challenges in mining.
• Existing filling materials often exhibit limitations in fluidity and expansion control.
• Development of advanced backfill materials is crucial for improving mining efficiency and safety.

Purpose of the Study:

• To develop and characterize high-flow, low-expansion backfill materials for improved mining applications.
• To investigate the effect of aluminum powder content on the properties of the backfill material.
• To evaluate the cost-effectiveness and filling performance of the developed material.

Main Methods:

• Formulation of backfill material with fixed fly ash content (80%) and varying percentages of mineral powder, lime, desulfurized gypsum, sodium carbonate, and aluminum powder.
• Assessment of material fluidity, expansion rate, and compressive strength at 90 days.
• Scanning Electron Microscopy (SEM) analysis to observe microstructural changes and hydration products.

Main Results:

• The developed backfill material exhibited good fluidity and a controlled expansion rate of 2%-3%.
• Compressive strength at 90 days ranged from 4 MPa to 5.5 MPa.
• SEM analysis revealed that increased aluminum content altered ettringite morphology and that interconnected hydrated calcium silicate gel and ettringite formed the primary structure.

Conclusions:

• The optimized backfill material demonstrates excellent performance characteristics for slurry transport and roof contact.
• The material's composition, primarily fly ash, mineral powder, lime, and gypsum, ensures readily available, low-cost raw materials.
• The developed backfill material offers a simple filling process and effective filling results, making it suitable for widespread mining applications.