To improve the copper flotation indices of a large copper-molybdenum mine, experimental studies on reagent regime and beneficiation process were carried out, and the influences of collector type and dosage, scrubbing and desliming parameters on flotation indices were investigated. The results of a closed-circuit test of copper flotation show that a copper concentrate with Cu grade of 23.22% can be obtained at 89.10% recovery under the optimal reagent system and renewed process conditions.

A process consisting of flocculation-sedimentation and chemical decalcification was adopted to treat mineral processing wastewater of a tungsten polymetallic ore with high suspended solid (SS) and Ca²⁺contents. The influence of flocculant dosage, stirring time, stirring speed, water temperature and pH value on flocculation-sedimentation performance was investigated, and the process was then optimized. A closed-circuit test of fluorite flotation with the recycled water shows that the flotation index obtained is similar to that using fresh water, indicating that the wastewater after treatment is applicable for fluorite flotation.

An experimental study was carried out to comprehensively recover lead and zinc resources from a refractory pyrrhotite lead-zinc sulfide ore grading 1.84% Pb and 4.53% Zn respectively. And a new ester collector of ZQ-11, in combination with 25^# dithiophosphate, was used to float lead minerals. After that, magnetic separation process was adopted to treat lead flotation tailings for desulfurization, and butyl xanthate was then used to collect zinc minerals from the desulfurized tailings. A closed-circuit test resulted in 89.49% Pb recovery into a lead concentrate grading 62.57% Pb and 3.30% Zn respectively, and 85.79% Zn recovery into a zinc concentrate grading 43.37% Zn and 1.01% Pb respectively. It is concluded that this process can actualize an effective recycle of refractory pyrrhotite-type lead-zinc sulfide ore.

The influence of Ce³⁺ in the sodium oleate system on the flotation of fluorite and calcite was investigated by flotation test, zeta potential measurement, solution chemistry study and X-ray photoelectron spectroscopy analysis. The results reveal that in the sodium oleate system, Ce³⁺ with a low concentration exists on fluorite surface in the form of CeF₃·0.5H₂O(s) under acidic and neutral conditions, therewith, fluorite can be activated to generate more active sites for the adsorption of sodium oleate. Meanwhile, Ce³⁺ can be adsorbed onto calcite in the form of Ce₂ (CO₃)₃·8H₂O(s). There are more active sites generated as well, but calcite may be depressed as the hydrophilic nature of Ce₂ (CO₃)₃·8H₂O(s) and the spatial site barrier effect of crystalline water hinder the adsorption of sodium oleate. In alkaline pulp, Ce³⁺ is mostly precipitated to form Ce(OH)₃(s) and depresses both fluorite and calcite as Ce(OH)₃ (s) can consume sodium oleate and reduce its adsorption on both minerals.

By establishing a particle flow model of geological profile with discrete element software PFC^2D, the formation and development process of overlying strata cracks during the mining of ore body were studied, and the mechanism for overlying strata gradually developing into collapse and caving was also revealed. It is found that with the mining of ore bodies, fractures grow upward and increase in numbers. The goaf after mining can cause the overlying strata with tensile-shear failure, and also the new cracks will constantly occur in the strata. Tensile fractures predominantly develop in the overlying strata, but tensile fractures occur at the both ends of fracture development region. Also, more and more concentrated fractures grow upward at both ends of goaf, presenting a potential of gradual collapse and caving of goaf roof. After the third and fourth stratified ore bodies are mined out, roof collapse will take place locally and then gradually develop into roof caving of the whole goaf, finally leading to roof collapse to the surface and forming a small sinkhole on the ground surface. Then, the development progress of sinkholes can be subdivided into stable stage, slow-progress stage, rapid-progress stage and end of progress in terms of the numbers of fractures, presenting the mechanism for overlying strata developing from tensile fracture and shear fractures at both ends of goaf to overall collapse.

For determining support parameters in an advancement project of the secondary shaft of Comica Mining's Kamoya copper-cobalt mine in the DRC, 25 sets of testing schemes were designed by using Box-Behnken based on the engineering geological conditions. After numerical analysis with FLAC^3D, the mechanical response characteristics under various support conditions were obtained. In combination with technical and economic requirement, analysis hierarchy process and principal component analysis were adopted for the combined weighting of nine selected indices, including advancement cost, maximum tensile stress among others, and then a comprehensive evaluating model was established for the parameters of shaft support. A multivariate second-order regression prediction equation was then obtained with the comprehensive scores as response indicators, and shaft support parameters as the variables. It is found that shaft is supported with 35 anchor bolts with thread length of 2.5 m arranged in horizontal direction, with spacing of 1 m in vertical direction, as well as the concrete lining with strength grade of C35, and the best comprehensive benefits can be obtained.

A database including 336 sets of engineering practical samples was established for rockburst prediction based on literature research. An improved salp swarm algorithm (ISSA) was adopted to optimize the support vector machine (SVM), and then an ISSA-SVM model was constructed for predicting the rockburst intensity grade and its effectiveness was also verified. Results show that this ISSA-SVA model for rockburst prediction can have accuracy up to 94.0%, much higher than other model, which can provide a certain scientific basis for rockburst prevention and control.

Based on the analysis of existence forms of molybdenum and iron ions in acidic solution with different pH, the solvent extraction processes available for separating molybdenum from iron were classified, for which the principles, effects, advantages and disadvantages were also discussed in detail. Moreover, the potential development trend of the solvent extraction for molybdenum and iron separation in the future is prospected, thus providing ideas for the research and development of a green and efficient process for separating molybdenum and iron from acidic solutions.

Pure quartz and pyrite minerals in the size range of 5-30 μm were taken in an experiment on viscosity under different pulp temperature and concentration conditions, for investigating the viscosity variation law of ultrafine particles. The results show that the viscosity for both minerals within the same size range increases along with the increase of pulp concentration, and the finer the particle, the greater the increasing rate. Furthermore, the viscosity variation of quartz is more remarkable．With the same pulp concentration, the viscosity of both minerals displays a declining-ascending trend as the temperature rises, which is more significant for finer minerals. The regression analysis shows that the correlation between viscosity and concentration of quartz and pyrite slurry are in line with the exponential fitting model. According to this analysis, the pulp concentration for ultrafine grinding should not exceed 40% and the optimum pulp temperature should be regulated at 50 ℃, which is beneficial for improving grinding efficiency.

The upper middle section in the West 2^#Mining Area of Jinchuan Longshou Mine, with the mining method changed from underhand cut-and-fill mining to sublevel caving without sill pillar, was taken as an example for studying extraction of the orebody in a confined space from sublevels of stope. A combined scheme was prepared with different ore-drawing method for each sublevel. As for the first and second sublevels, the total amount of mined ore in the ore drawing is controlled to ensure the safe caving of roof and forming of overburden. And ore drawing by controlling ore dilution is adopted for the third sublevel for avoiding ineffective dilution, so as to achieve high-quality ore recovery. For the fourth sublevel, a scheme of ore drawing by controlling ore dilution in the normal stope drift plus ore-drawing by controlling cutoff grade in an auxiliary extraction drift is designed to achieve a full and effective ore recovery. Experiments were then performed with three groups of different ore-drawing schemes, and results show that a combined ore-drawing scheme can achieve safe and effective mining of orebody in a confined space, but also has a significant advantage in controlling loss and dilution of ores, which can bring the mine good economic benefit from mining. It is concluded that this research can provide scientific theory and technical guidance for the following engineering practice.