By performing settling rate test, turbidity test, zeta potential measurements, solution chemistry study and extended DLVO theoretical analysis, the mechanism for sodium hexametaphosphate (SHMP) to disperse ultrafine potassium feldspar and hematite was investigated. It is shown that, Na_m (PO_3)n^m-n (m<n) anions derived from SHMP ionization can wrap around mineral grains in a form of spiral long-chain polymers, forming thick hydrophilic macromolecule protective films. Meanwhile, HPO₄^2-formed by hydrolysis can be adsorbed onto ore grains, leading to decrease of the surface potential and increase of the interparticle electrostatic and steric repulsions. In this case, mineral particles need to overcome a higher potential barrier to reach a stable condensed state. Therewith, the non-selective agglomeration of ore particles weakens, resulting in a significant improvement in dispersion stability.

The sulfur-containing cyanide leaching tails were taken for experimental research by using pyrolysis process in a rotary kiln for degradation to remove cyanide as well as sulfur fixation. The influence of temperature, atmosphere, shielding gas flow rate, and the time of constant temperature for pyrolysis process on the degradation effect were all investigated. After experiment, soil testing was performed to detest the toxicity of the leaching tails for determine the effect of the clean treatment. It is found that under the atmosphere of 95%N₂, after 2 hours pyrolysis at a constant temperature with the highest temperature at 500 ℃, the total cyanide content in the tails detected by soil testing is less than 0.04 mg/kg, showing the content of total cyanide, copper, lead and zinc after cyanide leaching all can meet the relevant requirements for class I general solid waste in GB 18599-2020. The sulfur fixation rate in the left slag is approaching 100% after pyrolysis, and there is no large amount of SO₂ in the flue gas during pyrolysis. It is concluded that clean treatment of cyanidation tails can be actualized by using this low-temperature pyrolysis process.

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.

In order to explore the current status of sustainable development of mining enterprises in China in recent years, static and dynamic analysis was performed for ecological efficiency of mining enterprises in 11 different sub-sectors in China from 2012 to 2020, in which SBM-DEA model with undesirable output taken into consideration was adopted in combination with GML index. And regression testing was also conducted in combination with Tobit model for the influencing factors for ecological efficiency. Results show that during the sampling period, the ecological efficiency of mining enterprises was generally trending up, but there was some difference in the efficient frontier, and great difference between each sub-sector. It is found that the technological advancement is the main driving factor for improving ecological efficiency, which is also positively correlated with high degree of interaction with outside world, but negatively correlated with environmental regulations. At last, as for improving ecological efficiency of mining enterprises, some recommendations are proposed for the state, mining sector and mining enterprises.

Arsenic-iron slag were treated by using magnetizing reduction for recovering arsenic and iron therein, and the experimental conditions were optimized as follows: roasting at 650 ℃ for 180 min, adding carbon at an amount of 25% and protecting with argon. Under such conditions, the arsenic volatilization rate reached 97.25% and arsenic content in the roasted slag decreased to 0.61%. It is found that arsenic can be recovered in the form of As₂O₃, with purity up to 99.13%, while iron therein is magnetized and can be recovered in the form of Fe₃O₄ by magnetic separation. Therefore, this process can actualize the resource utilization of arsenic-iron slag.

For the copper-containing acidic wastewater generated during underground mining process of a copper mine, a new processing technique consisting of copper recovery by replacement with iron filings, neutralization of alkaline tailings overflow, and treatment of coagulation and sedimentation was studied, and the effects of adding amount of iron filings, replacement reaction time and stirring speed on copper replacement rate were all investigated. And then, experiments on the proportion of required alkaline tailings overflow for neutralization of acidic wastewater and on toxicity characteristic leaching of neutralized sludge were performed, as well as the kinetics of replacement process was also studied. The results show that this new processing technique can produce sponge copper grading 35.6% Cu at 92.7% recovery, and the acidic wastewater after treatment can be up to the standard and directly discharged, with the cost of treatment agent at 0.95 yuan/t. Due to no hazardous waste generated, this processing technique can bring remarkable economic and environmental benefits.

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.

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.

A kind of spherical Mn₃O₄ was prepared in situ with manganese sulfate solution as raw material and air as oxidant, and the effects of factors, such as time and temperature of reaction process, the pH value of solution and air flow rate, on the properties of synthesized product were investigated. It is found that under the appropriated conditions, including reaction time of 6 h and reaction temperature of 80 ℃, pH of 9 for the solution and air flow rate at 20 L/min, the synthesized Mn₃O₄ has a micro-morphology of regular nano-spherical particles in a uniform size around 150 nm, showing a high crystallinity and a good dispersion. Its specific surface area is 9.85 m²/g and the tap density is 1.93 g/cm³.

A kind of refractory hematite-limonite ore containing 0.39% lead, 0.30% zinc and 47.04% TFe was taken to perform carbothermic reduction roasting experiment, and the reduction effect of hematite-limonite ore and the removal rate of lead and zinc in the reduction roasting process were all investigated. The reaction fraction, reaction rate and kinetic parameters of the reduction roasting process were studied by means of thermogravimetric analysis at a constant temperature, and the kinetics of carbothermic reduction roasting of refractory hematite-limonite ore was also discussed. After 60-min roasting at 1 200 ℃ with the reducing agents of carbon and oxygen at a ratio of 2.25, the obtained roasted ore was subjected to low intensity magnetic separation, resulting in the yielded iron concentrate grading 89.63% TFe at 86.09% recovery and the removal rates of lead and zinc up to 98.97% and 91.19%, respectively. The iron minerals are mainly transformed into spherical metallic iron particles with iron purity over 99.4% in micro-zone. The reduction roasting process of iron ore follows the shrinkage boundary control reaction mechanism and shrinkage core model. The apparent activation energy is calculated to be 91.37 kJ/mol, and the pre-exponential factor is calculated to be 18.09 min^-1, indicating that the rate-limiting reaction step is solid-state diffusion. This research can provide reference for removing harmful impurities from similar ores by reduction roasting process.