A self-designed multi-functional rod was adopted to provide a real-time monitoring of surrounding rock stability during the excavation of a metal mine, and the variations of vertical stress of rock stratum and surrounding rock vibration occurrence within the monitoring range of the multi-functional rod during stoping were all recorded. It is found that the stress and peak ground velocity of the surrounding rock are all trending up as excavation area increases, which reflects that more fractures occur inside the surrounding rock, leading to lower degree of stability for the surrounding rock, and the excavation damage zone (EDZ) goes deeper. As for mines supported by top threaded anchor bolts, the EDZ evolution process and caving of rock mass can be more effectively controlled when the thread length of rod is greater than the depth of EDZ. After one month's mining of this stope, it is found that the vertical stress of the rock stratum within the monitoring length of the multifunctional rod increases by 3.9 MPa due to the subsidence of the stratum, and the frequency of vibration occurrence meets the blast vibration standard for safety permit in China. It is shown that the surrounding rock has a good stability based on the comprehensive evaluation.

A flotation experiment was performed with medium grade siliceous and calcareous collophanite from Guizhou Province for determining the optimum technical process and reagent system. With the process flow consisting of three roughing, one cleaning and one scavenging, a high quality phosphate concentrate grading 34.07% P₂O₅ at 75.38% recovery was finally obtained. The adsorption behavior of collector SGC-01 on the apatite surface during the direct flotation process was also investigated by using Zeta potential, infrared spectrum and QCM-D. The results show that SGC-01 can be chemically adsorbed onto apatite in various forms, and presents a better flotation performance compared with sodium oleate.

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.

A coating of 316L+x%NbC (x=0,5,10,15) was prepared on the surface of 304 stainless steel by laser cladding, and the effect of NbC content on the phase composition, microstructure, micro-hardness and wear behavior of the prepared coating was then investigated. The results show that with NbC content at 5%-15%, the phase composition of coating consists of NbC, Cr₇C₃ and γ-Fe; while the prepared 316L coating by adding NbC has its matric structure significantly refined, and traces of Nb element are dissolved in the phase of γ-Fe, forming a gap solid solution. By adding NbC, the micro-hardness and wear resistance of coating are substantially improved, but the friction coefficient and wear rate are remarkably decreased. It is shown that the coating of 316L+15%NbC has micro-hardness as high as 381HV_0.3, friction coefficient of 0.437 by average (41% lower than the coating 316L), and wear rate of 2.95×10⁶ μm³/ (N·m), (around 50% compared to 316L coating).

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.

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.

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.

The impurities of iron and cobalt in nickel sulfate mixture solution were removed by oxidation with chlorine, and the varying pattern for the potential of metal ions and pH value during the chlorine oxidation was investigated. Based on the thermodynamic analysis, the proper potential range for removing iron and cobalt was determined. Meanwhile, the effects of pH value, temperature among other factors on impurity removal were also investigated. Results show that the reaction temperature has little influence on the removal effect of iron and cobalt, but pH value can bring great impact. It is found that under the following optimal conditions, including reaction at 50 ℃ for 140 min, agitation at a rate of 400 r/min, pH value initially at 1.6 and maximally at 4.0-4.5, potential controlled within the range of 0.62-0.64 V for the stage of iron removal and at 1.08 V for the stage of cobalt removal, the content of iron and cobalt in the solution of nickel sulfate mixture can be reduced to less than 0.4 mg/L and 1 mg/L, respectively. It indicates that the removal rates of iron and cobalt approach 100%, meeting the requirement in the actual production of a domestic company (with iron content less than 1 mg/L and cobalt content less than 2 mg/L). Furthermore, the loss of nickel in this removal process is around 0.5%.

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.