Design of comprehensive test system for detecting overlying strata mining-induced fractures on surface with radon gas

Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive measurement method to detect the development process of the overlying strata mining-induced fractures and their contained water quality in underground coal mining, which not only innovates a more simple-fast-reliable detection method, but also further expands the applications of radon gas detection technology in mining field. A 3D simulation design of comprehensive testing system for detecting strata mining-induced fractures on surface with radon gas (CTSR) was carried out by using a large-scale 3D solid model design software Pro/Engineer (Pro/E), which overcame three main disadvantages of ''static design thought, 2D planar design and heavy workload for remodification design'' on exiting design for mining engineering test systems. Meanwhile, based on the simulation design results of Pro/E software, the sta- bility of the jack-screw pressure bar for the key component in CTSR was checked with a material mechan- ics theory, which provided a reliable basis for materials selection during the latter machining process.

Key Technology Research on the Efficient Exploitation and Comprehensive Utilization of Resources in the Deep Jinchuan Nickel Deposit

To understand the resource features and geology in the deep Jinchuan nickel deposit, difficult geological conditions were systematically analyzed, including high stress, fragmentized ore rock, prevalent deformation, difficult tunnel support, complicated rock mechanics, and low mining recovery. An integrated technology package was built for safe, efficient, and continuous mining in a deep, massive, and complex nickel and cobalt mine. This was done by the invention of a large-area continuous mining method with honeycomb drives; the establishment of ground control theory and a technology package for high-stress and fragmented ore rock： and the development of a new type of backfilling cement material, along with a deep backfilling technology that comprises the pipeline transport of high-density slurry with coarse aggregates. In this way, good solutions to existing problems were found to permit the efficient exploitation and comprehensive utilization of the resources in the deep Jinchuan nickel mine. In addition, a technological demonstration in an underground mine was performed using the cemented undercut-and-fill mining method for stressful, frag- mented, and rheological rock.

Applicable conditions for a classification system of aquifer-protective mining in hallow coal seams

Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at the Shendong Mine. We have selected the height of the water-conducting fracture zone in overlying strata as a composite index and established the applicable conditions of aquifer-protective mining in shallow coal seams with a multi-factor synthetic-index classification method. From our calculations and analyses of variance, we used factors such as the overlying strata strength, mining disturbing factors and rock integrity as related factors of the composite index. We have classified the applicable conditions of aquifer-protective mining in shallow coal seams into seven types by comparing the result of the height of water-conducting fractured zones of long-wall and short-wall working faces with the thickness of the bedrock, the thickness of the weathered zone and the size of safety coal-rock pillars. As a result, we propose the preliminary classification system of aquifer-protective mining in shallow coal seams. It can provide a theoretical guidance for safe applications of aquifer-protective mining technology in shallow coal seams under similar conditions.