Preliminary study on the feasibility of co-exploitation of coal and uranium

Abstract

Both coal and uranium resources are found in the Dongsheng area which is located in the northern part of Ordos Basin, China with the coal seam below the uranium deposit. In this paper, we attempt to study the feasibility of co-exploitation of the coal seam and the uranium deposit. The permeability evolution in strata around the coal seam are selected as the key parameter indexing the separate and safe concurrent recovery of two deposits and a novel strain-dependent permeability model is proposed covering the full deformation range of rock. The proposed model is first verified with experimental data with good fitting of the results. Then an upscaled numerical model is established considering the geology conditions of Dongsheng area. This is implemented using COMSOL Multiphysics; and the interface of COMSOL with MATLAB is used to study the damage to the rock mass. We show that (a) compared with the stress-dependent permeability model, the strain-dependent permeability model proposed in this work has the advantage that each strain value is associated with a unique permeability value; (b) The feasibility of co-exploitation of the coal seam and the uranium deposit depends on the relative distance between two resources. When the caved and fractured zone encroaches on the uranium deposit the coal seam should be abandoned. Conversely, when the uranium deposit lays in the constrained zone, the recovery of the coal seam would benefit recovery of the uranium deposit; (c) The feasibility of the co-recovery of the two resources can be optimized by the choice of mining approach. The top-caving mining approach and room-and-pillar mining approach can reduce the height of the caved and fractured zones and make the co-exploitation of the uranium and coal feasible. This work provides a new approach to investigate the feasibility of co-exploitation of uranium and coal.