Optimization of Concurrent Mining and Reclamation Plans for Single Coal Seam – a Case Study in Northern Anhui, China

Abstract: The extraction of underground ore body inevitably causes a large amount of land subsidence. Current reclamation technologies in China mainly focus on stable subsided land. Therefore, a new technology for reclaiming unstable subsiding land is being studied for restoring farmland as much as possible based on a case study in Northern Anhui, China. In consideration of the mining plan, subsidence processes in various stages were analyzed and some related factors such as vertical subsidence, post-mining slope, water area, and land use condition were also generated. Due to mining activities, useful farmland gradually decreases to merely 14.4% of the pre-mining area. In this study the following stages were modeled from pre-mining to post-mining: (1) rate of farmland was 100% in stage (a) (pre-mining), (2) 72.5% in stage (b), (3) 67.3% in stage (c), and (4) 14.4% in stage (d) (post-mining). The results show that 86.6% of cultivated land was submerged into water and lost its capacity for cultivation. Reclamation plans for stages (b), (c), and (d) were made by a traditional reclamation method called “Digging Deep to Fill Shallow”. Based on scenario simulation, the farmland reclamation rates were improved to 78.3%, 73.3%, and 40.70% respectively. Taking the rate of reclaimed farmland as preferred standard, concurrent mining and reclamation for stage (b) and(c) could increase farmland reclamation rates to 37.6% and 32.6% respectively, compared with the farmland reclamation rate of post-mining. The results reveal that optimum reclamation time should be at stage (b). Therefore, under current technical conditions, concurrent mining and reclamation could enhance the quantity of cultivated land, and provide better land-protection and food security in high water table mined areas.