| Mining of residual ores in old goafs is a very complicated engineering. On basis of field investigation results of practical mining of residual ores in old goafs of FengHuangShan Limited Liability Company, using fuzzy optimizations, theoretical analyses, numerical simulations and industrial tests, optimal problems of residual ores mining are studied deeply. The main contents and conclusive results are as follows:(1)In the process of field investigations, guided by the in-situ experienced geological engineer and combined with using some portable detection tools, such as the electronic distance meter and geological compass, three-dimension distributions of goafs are grasped basically and occurrence, thickness, grade and other relative detailed geological information of residual ores are obtained.(2)According to mining technology conditions, three typical mining plans are chosen, they are respectively pillarless sublevel caving method, slicing and caving method and sublevel shallow-eye caving method with pear-shaped accesses. A variety of fuzzy and subjective factors representing the mining process are transformed to mathematical forms by fuzzy optimation method. By quantitatively analyzing evaluation indicators of those plans, pillarless sublevel caving method is the optimal mining plan.(3)The activity of caved ores is the typical movement of granular media. Based on former research results of movement laws of granular media, combined with practical mining of residual ores, the optimal mining parameters are obtained in order to improve ore recovery rate and reduce ore loss and dilution. According to original drawing mode and accumulation laws of residual ores in the stope floor, residual ore reserves of each stope are estimated, which can provide reliable references for mining design.(4) Structural parameters of the mining method is directly related to ore recovery index and recovery effects, thus affecting the overall technical and economic indicators and efficiency of mining, through the study of releasing ore law, combined with the theoretical knowledge of the releasing ore, a series of optimization of the FengHuang Mountains pillar and residual ore of footwall recovery parameters to achieve maximum recovery of ore.(5) As the ore body dip is not very steep,and ore with a larger adhesion,there will be a large number of ore backlog no released. So we need broke some of footwall rocks, based on the technical and economic point of view, optimize the height of the broken rocks of the footwall. |
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