Nonlinear constrained multivariable spatiotemporal collaborative optimization model for coal and gas co-mining

The realization of coal and gas co-extraction is an inevitable way to exploit deep coal resources.The engineering application of coal and gas co-extraction technology in China has already taken rudiment, but currently the basic theoretical system of coal and gas co-extraction has not yet been established, which should have validity, scientificity and pertinence to the co-extraction technology.Because of the poor time-effect, poor synergy, low efficiency of gas extraction and the tense production succession relationship in the co-extraction of coal and gas, it leads to coal mining before the gas extraction meeting the standard, causing a greater potential safety hazards to coal mining.At present, it is not clear how much the reasonable value of gas extraction and coal extraction should be, how long the gas extraction should take, and how the coal mining and gas extraction work should be connected.In the coal and gas co-extraction, while pursuing the maximization of the total financial returns from the two resources, the maximum recovery rate of coal and gas resources should be satisfied, and the optimal coal and gas extraction quantity should be sought, which makes the coal mining system and gas extraction system interact from disorder to orderly coordination.Based on the synergy and theory of system optimization, the model of coal mining and gas drainage is established.Under the premise of meeting safety regulations and gas extraction standards, the mutual promotion and restriction relationship between coal mining at key time points and space points of gas pre-extraction, production gas extraction, and extraction of gas in goaf during coal and gas co-mining and gas extraction is a constraint.The optimization objective function is coal recovery rate, gas recovery efficiency and economic benefit maximization.The factors such as mining cost, coal price, safety factors and macro policy are taken into account, taking coal production amount, pre-mining gas drainage quantity and gas drainage quantity in mining, gas drainage quantity in goaf, gas discharge quantity by air, extraction time in goaf, pre-drainage time of gas in working face, average daily yield as optimization variables, a nonlinear constrained multi-variable spatiotemporal cooperative optimization model of coal and gas mining is established, and a program for solving co-mining optimization is developed.In a case study, the 24207 co-mining working face of Shaqu Coal Mine is optimized, and the results show that the resource recovery efficiency and benefits are improved, and the validity of the model is verified.The study achieves a spatiotemporal co-mining of coal and gas with a theoretical basis.