Key Techniques Of Multi-coal Seams Mining Under Condition Of Adopting Blast Casting

The development modes of Surface coal mines present large-scale operations and intensive management. They are more important in strengthening scientific, and technological innovations and progresses to reduce the production costs and improve the resources recovery ratio, to enhance the coordinated and sustainable development of resources, society and the environment. Although blast casting is applied in surface coal mines as an inexpensive stripping technique, it is associated with restrictive factors resulting in major effects in following the resource mining approaches. Several subjects and theories such as surface mining, blasting engineering, modern mathematics methods and systems engineering were synthetically applied to study the applicable conditions of blast casting and resource recovery issues under its influence.According to the trajectory theory process of rock casting, the main factors influencing the effect of blast casting such as the ratio of bench height to width, hole inclination, explosive consumption, the time interval of delay, pre-split blasting and hole pattern parameters were determined. The analysis model of the correlation degree between the factors influencing blast casting was established on the basis of the Factor Analysis Method. Blast casting effect evaluation model was established by adopting fuzzy mathematics principle and set-valued statistical theories.Major features of blast casting technique and muck pile morphological characteristics were analyzed in accordance with the surface mining principles. The bench slope surface form was determined as the basic factor influencing the design of optimum charge resistance line. The basic methods of bench slope data vectorization, data processing and coordinate transformation were also described while the influence mechanism of vibration of coal stripping to open pit slope stability was analyzed. Combining the reliability of equipment with the statistical characteristics of blasting pile, the relationships influencing the degree to which the mining parameters affects the production capacities were determined after analyzing the sensitivities of parameters. Blast casting bench height is the key factor influencing the production capacity, followed by dragline steady availability and effective casting ratio, and lastly is the working face length and working line length. The key factor in choosing the way of blast casting in Multi-seam mining was determined and the major factors influencing process matching, type, adaptability and application were analyzed. The decision index of blast casting process matching was determined from three aspects, which are the minimum advance degree for capacity, the effect of downstream production links and the equipment investment and production cost. Then the production cost mathematical models for the former-design and later-design were established. Taking mine capacity as a constraint and combining it with the operation mode and production capacity of equipment, the production capacity model was established for choosing mining schemes of multi-seams under blast casting conditions in accordance with the cast blasting muck pile morphological characteristics and influence on the subsequent mining and dumping. A comprehensive optimization model for choosing mining schemes was established based on TOPSIS principle. The relationship of blast casting relative position height to casting distance was analyzed. It is determined that under the condition of multi coal seams, blast casting position height could increase the casting distance of rock block significantly, thereby improving the casting ratio. Blast casting bench parameters were analyzed under the condition of multi-coal seams, nonlinear programming models for mining panel width and bench height were established, as well as multi-objective optimization model for working line length. Mining sequence and development transport system were analyzed under the condition of blast casting. The advancing distance optimization model of the different development transport system was established. Factors affecting the mining advancing rate and the variation of the slope stability with the mining advance were analyzed, the results which shows that the slope stability factors decreases with increased end-wall area.