Liu, P 2017, 'Technologies and practices of mechanized backfill mining for water protection with aeolian sand paste-like', in A Wu & R Jewell (eds), Proceedings of the 20th International Seminar on Paste and Thickened Tailings
, University of Science and Technology Beijing, Beijing, pp. 284-293, https://doi.org/10.36487/ACG_rep/1752_32_Liu
Given the serious problem of Salawusu Formation Aquifer damage caused by caving mining in Yuyang Coal Mine, the technique of mechanized mining backfill with paste-like slurry using Aeolian sand was invented. The backfill used Aeolian sand as aggregate and alkali-activated fly ash as the cementing agent. The water-sand ratio was 1:1.3, with a mass concentration of 72%, and the initial fluidity of the filling slurry reached 210 mm. This paper proposes a calculation method for the local resistance loss of slurry transportation with pipeline, and the field gravity transport test results showed that the resistance loss of unit length elbow was 4.26 times as great as that along the path. Therefore, the pipeline diameter for the 14.9 lines of self-flowing was determined, and the pipeline flow design precision was improved by over 10%. The filling capacity reached 360 m3/h and the running energy consumption was low after adopting the filling station model of double pulping system and underground equipment pool. The paper also puts forward the method of whole filling space sealing with a cloth consumption being only 40% of that using the bag filling. Industrial test showed that the technique also protected water resources, based on the fact the filling rate was 98.5% in goaf, strata behavior slightly appeared, roof water leaching was less than 2 m3/d, and the surface subsidence value was 38 mm. Meanwhile, great breakthroughs have been achieved in lowering and improving production efficiency compared with similar technology.
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