Theories and technologies for in-situ fluidized mining of deep underground coal resources

As a national strategy,deep resources mining has been of great importance. However,current theory,tech- niques and methods cannot satisfactorily solve the technical and environmental problems in deep mining. It is critical to reform the current methodology. Guided by the coal industry revolution and with an aim to solve the bottleneck difficul- ties for over 2 000 m deep mining,this paper systematically presents the scientific conception of deep in-situ mining, and the theory and technical system of fluidized mining for deep underground mineral resources. Specifically,four theories were depicted in this paper,including (i) mining induced rock mechanics,(ii) " three fields" visualization,(iii) in-situ multi-physics coupling and design,and ( iv) the conversion and transportation of in-situ fluidized mining for deep underground coal resources. To support the four theories,ten techniques were provided,including ① geological safeguard,② accurate exploration and navigation,③ intelligent development and layout of mines,④ intelligent coal washing,⑤ in-situ intelligent mining-preparation-backfilling and conversion of electricity-steam-heat,⑥ intelligent transport and lifting,⑦ energy-induced physical fragmentation,⑧ in-situ chemical conversion,⑨ in-situ biological degradation,and ⑩ in-situ pulverized coal deflagration power generation. Finally,the strategy of deep in-situ fluidized mining was developed.