Aiming at the ecological degradation and damage mechanism of open-pit limestone mines in Jinan, the evaluation index system of ecological vulnerability of open-pit limestone mines in Jinan was constructed based on the "pressure-state-response" (PSR) model framework, including the ecological and environmental elements of the mining area. The engineering application analysis was carried out in Lijiawo abandoned open-pit mine in Jinan. The research shows that the four indicators of landslide prone degree, degree of surface subsidence in the mining area, vegetation coverage and soil erosion can be restored in a short time, which can be used for the acceptance of ecological restoration projects and the evaluation of short-term restoration effects in mine. The measures taken to achieve the short-term restoration effect of ecological system in mines can be regarded as the starting point of the artificial promotion of natural restoration mode. The inverse method based on the limit value of EVI can be used to quantify the degree of artificial interference, and it is considered that the vegetation coverage can achieve ideal natural restoration effect when EVI=3.75. The research puts forward the ecological restoration strategy of "ecological remodeling, regional renovation, landscape reconstruction", which can provide theoretical basis and practical guidance for the ecological restoration work in similar mining areas.

In explosive hazardous environments, transient energy still transfers to the load when the semiconductor switching element of the current-intercepting intrinsically safe power supply cuts off the overcurrent main circuit. In view of this problem, a scheme was proposed to add transient suppression components in the overcurrent protection circuit to reduce the rising rate of short-circuit current and thereby suppress transient energy. Through the analysis of the short-circuit discharge process, a mathematical model of short-circuit discharge was established. Multisim was used to simulate and analyze protection circuits with different inductance values, and the nonlinear relationship between inductance parameters and transient energy was obtained. Increasing inductance can suppress the amplitude of transient current, but excessive inductance will prolong the protection response time, leading to energy accumulation. Based on the short-circuit discharge model, an intrinsically safe power supply was designed and fabricated. The test results show that increasing inductance can effectively suppress short-circuit current and transient energy. A 47 μH inductance can reduce the short-circuit current to 0.988 A and the transient energy to 1.17 μJ, which are 87.3% and 33.9% lower than those of the inductance-free circuit, respectively. Combined with the parallel freewheeling diode, the peak transient voltage has been limited within the safe threshold, which provides a theoretical and test basis for the transient suppression design of intrinsically safe power supplies.

As an auxiliary collector, tributyl phosphate has lots of shortcomings, such as high sensitivity to process conditions, unstable foam, low recovery rate and high reagent consumption in cassiterite flotation of a concentrator in Yunnan. In order to solve these problems, a new type of auxiliary collector SN-F was developed. The adaptability of two auxiliary collectors under different slurry pH, flotation concentration, grinding fineness and aeration rate was compared and investigated through conditional and industrial experiments. The results show that SN-F performs the best when the slurry pH is 6–8 and the slurry mass concentration is 45%. The recovery effect of cassiterite adding SN-F under the condition of grinding fineness of －37 μm accounting for 72.11% is significantly better than that adding tributyl phosphate. The industrial test results show that SN-F can increase the cassiterite recovery rate by 10.69 percentage points, improve the concentrate grade by 0.63 percentage points, and reduce the reagent cost by 34.31%. The auxiliary collection capacity and foam stability are good, and the adaptability to complex slurry is stronger, providing an economical and feasible solution for the efficient separation of fine-grained cassiterite.

The main valuable elements of a copper-molybdenum ore in Pakistan are copper, molybdenum, gold and silver, with copper content of 0.55% and molybdenum content of 0.01% in the raw ore. The contents of associated gold and silver are 0.1 g/t and1.15 g/t respectively. The content of easily mudding gangue minerals such as sericite and chlorite in the ore is high, resulting in a low grade of copper concentrate. In order to solve the above problems, a new-type inhibitor CD-B was developed to inhibit mudding gangue minerals. The process flow of “rough grinding, three-stage roughing with tailings discharge, rough concentrate regrinding and recleaning” was adopted. A copper-molybdenum mixed concentrate with a copper grade of 26.76% and a molybdenum grade of 0.451% can be obtained. The copper recovery rate is 94.49% and the molybdenum recovery rate is 77.48%. The copper-molybdenum mixed concentrate contains 2.06 g/t gold and 32.66 g/t silver, with gold recovery at 40.17% and silver recovery at 55.38%, demonstrating good beneficiation indicators. The new-type inhibitor CD-B is a small-molecule organic compound, featuring zero toxicity, zero pollution, low reagent consumption, and belongs to a high-efficiency green environmental protection reagent. Compared with the conventional reagent of sodium silicate, CD-B can significantly improve the grade of copper concentrate. The consumption of CD-B is only 1/15 of that of sodium silicate, making it convenient for procurement, storage and use.

In order to solve the incompatibility between the green development capability indicators of non-ferrous metal enterprises and the lack of full consideration of subjectivity and objectivity in the process of index weighting, an evaluation model of green development capability of non-ferrous metal enterprises based on game theory combined weighting-improved matter-element extension model was proposed. Firstly, through literature analysis and consulting experts, the evaluation index system of green development capability of non-ferrous metal enterprises was constructed. Secondly, the subjective weight and objective weight of the evaluation index were calculated by the genetic algorithm-analytic hierarchy process and the CRITIC method respectively, and the comprehensive weight was calculated according to the game theory. Finally, the asymmetric closeness degree criterion was used to replace the maximum correlation degree criterion, and the evaluation model of green development capability of non-ferrous metal enterprises based on the improved matter-element extension model was established, and the model was studied by an example. The research results show that the evaluation grade is consistent with the bias degree of the previous year, which verifies that the green development capability evaluation of non-ferrous metal enterprises based on the improved matter-element extension model has certain reliability and accuracy.

In order to solve the problems of significant reduction of rock mass mechanical strength, poor integrity and extremely complex mining technical conditions in the 28-48 line ore body area of the deep −625 m middle section of Lilou Iron Mine due to the influence of weathering zone and fault cutting. The rock mass quality evaluation of four kinds of ore rocks in the upper and lower plates of the ore body area was carried out. It is found that the surrounding rock of the roof is poor, and the outer roadway of the vein should be arranged as much as possible in the stable marble of the lower plate. Based on the rock mass quality evaluation and the roadway failure mechanism analysis, four schemes of no support, bolt+steel arch support, bolt-shotcreting support and bolt-shotcreting+steel arch combined support were selected. FLAC3D software was used to simulate and analyze the stability of surrounding rock of deep −625 m middle roadway under four support schemes. The results show that compared with the no support, the minimum principal stress under the scheme of bolt+steel arch support, bolt-shotcreting support and bolt-shotcreting+steel arch combined support is reduced by 4.05%, 14.02% and 11.59% respectively, and the maximum subsidence of vertical displacement of roof is reduced by 10.33%, 42.46% and 43.35% respectively. The support effect of roadway surrounding rock from weak to strong is no support<bolt+steel arch support<bolt-shotcreting support≈bolt-shotcreting+steel arch combined support, and the support effect of bolt-shotcreting+steel arch combined support scheme is the best. After comprehensive consideration, it is considered that the selection of bolt-shotcreting support scheme can meet the support requirements of most mine weathering zone areas. Only in the extremely broken area, the bolt-shotcreting+steel arch combined support scheme is recommended. The research results can provide a basis for the subsequent operation and production of deep middle roadway and stope mining.

In order to solve the problem of difficult roadway support in deep crushed surrounding rocks, the range of plastic zone was studied. Taking the roadway in the crushed section of a mine as the engineering background, the current situation of roadway damage was investigated, and from the physical properties of the roadway surrounding rock itself, the influences of cohesion and internal friction angle on plastic zone were analyzed by theoretical analysis and numerical simulation system. The results show that the reason for the failure of the roadway under the original support is the poor nature of the surrounding rocks and the neglect of the plastic zone by the support parameters. The cohesion and internal friction angle of surrounding rocks have a significant influences on the range of plastic zone. When the cohesion and internal friction angle are large, the range of plastic zone is small and the surrounding rocks of roadway tend to be stable. When the internal friction angle is 35° and the cohesion is 3 MPa, the change curve of the plastic zone radius turns, which indicates that the combined parameters are the key threshold of the bearing capacity of the surrounding rocks. According to the theoretical analysis and numerical simulation results, the combined support scheme of "anchor (rod), net, spray + full-section anchor cable" was proposed. The field displacement monitoring shows that the maximum deformation of the two sides is about 40 mm, and the maximum deformation of the surrounding rocks of the roof and floor is about 61 mm, which effectively guarantees the stability of the surrounding rocks. The research results provide a theoretical basis for the support technology of deep crushed surrounding rocks in roadway.

With the depletion of shallow resources, deep mining has become the normal state of mineral resources development in China. Taking the approach stope at a buried depth of 1 000 min a mine in Yunnan as the research object, the borehole coring was carried out and the uniaxial compression test and Brazilian splitting test were carried out. Based on the Hoek-Brown criterion and Mohr-Coulomb criterion, the mechanical parameters of surrounding rock mass were obtained, and the numerical simulation study under different approach layout directions was carried out. The influence of principal stress direction on the stability of surrounding rock in approach stope was discussed, and the approach layout scheme was optimized. The test results show that the average uniaxial compressive strength, tensile strength and elastic modulus of the rock in the 1 000 m buried depth range are 96.48 MPa, 3.92 MPa and 33.87 GPa, respectively, and the rock has obvious brittle characteristics. The approach layout direction has a significant influence on the stability of the stope. The simulation results show that with the increase of the angle between the approach direction and the principal stress direction, the displacement and deformation range of the surrounding rock increases. When the approach direction is parallel to the principal stress direction, the displacement deformation of surrounding rock is the smallest and its stability is the best. Based on the numerical simulation results, the mechanical mining industrial test was carried out with the principal stress direction as the excavation direction, and the size of the stope approach was expanded to 4 m×4 m. It is found that the stability of the approach stope is good under the small operation disturbance of mechanical mining.

In view of the technical problems of safe and efficient mining faced by a large iron mine in Anhui province under the complex mining technology conditions, based on the comprehensive investigation and analysis of resource endowment characteristics, mining technology conditions and goaf status, a three-dimensional visualization model of the stope was constructed, and the collaborative mining scheme of upward horizontal layered filling method and sublevel open stoping with subsequent filling method was preliminarily determined. The MIDAS numerical simulation software was used to optimize the stope parameters. The results show that for the ore section at −470 m to −390 m, the upward horizontal layered filling method is suggested to be used, and the optimal stope span is 15 m, with a maximum tensile stress of 0.795 MPa on the roof. For the ore section at −390 m to −330 m, the sublevel open stoping with subsequent filling method is proposed, and the optimal stope span is 18 m, with a maximum tensile stress of 1.763 MPa on the roof. The engineering practice shows that the adoption of collaborative mining scheme has significantly improved the economic benefits of the mine, with a production capacity of 287−354 t/d, a recovery rate of 76.65%−90.82%, and a dilution rate of 3.95%−4.61%.

In order to reasonably determine the thickness of the Quaternary water-resistant roof pillar and the width of water-resistant pillar in the fault of an iron mine in Luanzhou, taking a mine using typical filling mining method in Luanzhou as the engineering background, through theoretical analysis, based on the size optimization of the mine water-resistant pillar, the stability of the optimized size was evaluated by the large-scale finite element numerical calculation model. The results show that after the excavation and filling of the designed ore body, the influence area height under the maximum displacement does not intrude the Quaternary lower weathered rock strata. The maximum and minimum principal stresses are compressive stress, and there is no tensile stress area, which does not exceed the compressive strength of surrounding rocks and is close to the compressive strength of weathered rock strata. Weathered rock does not produce plastic zone failure unit. The sensitive area of the overall displacement of the fault and the pillar is distributed in the range of 0−30 m. The maximum and minimum principal stresses of fault and pillar are compressive stress, and no tensile stress occurs. The compressive stress in the contact area between the fault and the surrounding rock reaches the plastic strength, and the principal stress in the pillar area does not exceed the strength of the pillar. The contact area between the fault and the pillar, the contact area between the fault and the surrounding rock locally produces plastic zone, and the penetrating area is not formed. The ore body above −110 m level is set as the roof pillar to meet the safety requirements of water-resistant mining in weathered rock strata. A 100 m water-resistant pillar is left on the north side of the fault and a 60 m water-resistant pillar is left on the south side to meet the safety requirements of water-resistant mining. The research results can provide a reference for the design and evaluation of water-resistant pillar in the process of underground mining in similar mines.