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The microbial induced carbonate precipitation(MICP) technology is proposed in the field of backfill mining to tackle high emission and high energy consumption in the current backfill system.Specifically, mechanical properties of microbial cemented backfill materials are investigated, and a proposal of microbial cemented backfill mining technology is presented in this paper.Results show that the strength of mixed and grouted microbial cemented backfill first increases and then decreases with the increase of cementation solution concentration and bacterial solution dosage.The average strength is 0.88 MPa and 17.95 MPa respectively.The effective CaCO3 crystal in the microbial backfill material is the key to its consolidation.The CaCO3 crystal of the mixing sample exists in the form of calcite and vaterite, and mainly calcite in the grouted sample.Microbial cemented backfill mining technology has significant environmental benefits such as energy conservation and emission reduction.There is happy prospect for this technology under current environmental needs and policies.

The scientific filling effect characterization is very important for backfill mining. A new filling effect index, the final backfill ratio (FBR), is proposed through experimental tests and theoretical analysis, and the sensitivity of FBR is studied in this paper. The control method of FBR is obtained and applied to optimise the filling effect for the backfill panel in Kailuan Group in China. It is concluded that every 0.05 m reduction of the void between the filling body and roof corresponds to 1.87% increase in FBR. FBR increases by 1.47% and 3.15% respectively when the UCS of the backfill body increases from 2MPa to 3MPa and 4MPa. [ABSTRACT FROM AUTHOR]