The adsorption of phosphate ions and oleate ions onto CO₃^2- defects on dolomite (104) surface was studied by using density functional theory (DFT) calculation. The results showed that the CO₃^2- defects that were generated due to dolomite dissolution led to the enhancement of the activity of metal atoms on the surface, which was beneficial to the interaction between anions and mineral surface. The adsorption energies of H₂PO₄^- onto calcium atoms on the ideal dolomite surface and the defective dolomite surface were calculated to be -183.30 kJ/mol and -561.24 kJ/mol, respectively. Based on the calculation of density of states, it was found that after adsorption of H₂PO₄^- onto the calcium atoms on the surface of defective dolomite, the adjacent magnesium atoms still had strong activity, and the adsorption energies of oleate ions onto the magnesium atoms on the surfaces of the ideal dolomite and defective dolomite were -52.29 kJ/mol and -489.43 kJ/mol, respectively. Phosphoric acid ions and oleic acid ions were adsorbed together on the surface of dolomite, resulting in the floating of dolomite.

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 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.

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.

For solving the problems of coarse feed size for grinding and high energy consumption in processing Daye Iron Ore, an experiment was carried out with high pressure roller grinding (HPRG) to mill the fine crushing products. The parameters of pressure between rollers, the water content of feed and the rotational speed at roller surface were optimized correspondingly as 10 MPa, 2% and 0.26 m/s. A closed-circuit test shows that HPRG can obviously reduce grinding energy consumption and improve mineral liberation degree. Jaw crushing and HPRG products were then taken as the feed for grinding-flotation test and it is shown that HPRG can improve flotation recovery, with recoveries of Cu, Fe and S all up by 2.56, 1.93 and 1.44 percentage points, respectively.

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.

In order to investigate the influence of additive on iron recovery from red mud by using a process consisting of magnetizing roasting and low intensity magnetic separation, a kind of red mud containing high content of iron and aluminum was taken for experiments. It is found that addition of dolomite and phosphogypsum won't bring any effect to iron recovery, but sodium sulfate can bring an obvious activation effect. In the experiment, the roasting process ran at 650 ℃ for 90 min, with the addition of sodium sulfate at an amount of 10%, with total gas flow at a rate of 500 mL/min and CO at a volume fraction of 30%. And then, the obtained calcine, after being ground to a fineness of -0.045 mm 65%, was subjected to a magnetic separation with magnetic intensity of 68.8 kA/m, yielding an iron concentrate with 60.65% TFe grade at 94.01% recovery. The subsequent thermodynamic analysis showed that at the temperature within the tested range, both dolomite and phosphogypsum were conducive to the decomposition of iron olivine rather than iron spinel, while sodium sulfate could work for both.

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%.

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.

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.