A core of uranium deposit was taken in an experiment of column leaching with alkaline solution (NaHCO₃+H₂O₂), and then the surface characteristics and pore distribution of sandstone-type uranium deposit were analyzed by using scanning electron microscope images. The variation in the microscopic pore structure of uranium-bearing sandstone in alkaline in situ leaching process was characterized by using T₂ spectrum of nuclear magnetic resonance (NMR). The results show that the matrix in the core firstly becomes connected pores due to chemical dissolution of leaching solution, resulting in more pore throats among large and small pores. The Al(OH)₃ mineral colloid and CaCO₃ generated by the reaction are deposited intensively in the pores and microcracks, which reduces the effective reaction area between leaching solution and matrix, thus reducing the uranium leaching efficiency. During the period of 97-158 h, dissolution is predominant, leading to the amount of chemical dissolution much higher than the amount of precipitation and accumulation, thus forming a large number of connected pores. Further reaction and dissolution of uranium minerals in the leaching solution can increase the recovery of uranium mineral to the peak.

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%.

In order to study the energy distribution of blast wave propagation, the EEMD and Hilbert transform techniques were adopted to analyze the blast vibration signals at the same measuring point in different directions, on the same line with different distance away from explosion center, as well as with the same distance away from explosion center but with different maximum charges. It is found that vertical signal energy is mainly concentrated in the midbands, while the radial signal energy in horizontal direction is distributed in both the mid- and low-bands, and tangential signal energy in the horizontal direction is mainly concentrated in the high-bands. Under the same monitoring, a greater attenuation is found in high frequency energy and the proportion of signal energy distribution shifts from high-bands to low-bands as the distance is farther away from the explosion center. However, with the same distance away from the explosion center, increasing the maximum charge in a single stage can lead to higher proportion of low frequency energy, and significantly increased charge can bring more obvious effect.

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.

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.

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.

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.

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.

The effect of rolling reduction on the microstructure, damping properties and mechanical properties of ZK60 magnesium alloy were studied. The results show that the damping properties of ZK60 magnesium alloy is improved with the increase of rolling reduction. When the strain amplitude is 0.01%, the Q^-1 value increases from 0.012 7 in as-cast state to 0.015 9 on rolling surface (RD-TD) with the rolling reduction of 50%, 0.020 4 on side section (RD-ND) and 0.018 3 on cross section (TD-ND). With the increase of rolling reduction, the (0002) basal texture strength of the alloy increases from 6.547 with the rolling reduction of 10% to 10.690 with the rolling reduction of 50%, which brings a certain impact to the damping properties of the alloy. The increased recrystallization volume fraction in the microstructure is the main influencing factor for the damping properties.

Aiming at the commercial production problems in the usage of high-temperature reagents for the reverse flotation in Qidashan Concentrator, a new laboratory-prepared combined collector (AG-1) was adopted in the reverse flotation of mixed magnetic concentrate at room temperature (20 ℃). The results show that a reverse flotation flowsheet consisting of one stage of roughing, one stage of cleaning and three stages of scavenging, with pulp pH of 11.5, the dosages for depressant (corn starch), activator (CaO) and collector (AG-1) at amount of 950 g/t.100 g/t and 750 g/t, respectively, can yield an iron concentrate grading 68.13% TFe at 88.43% recovery. XRD patterns and optical microscopy visualization of flotation concentrate and tailings show that AG-1 has good selectivity, and can effectively separate valuable minerals from gangue mineral of quartz. Compared with the single collector of sodium oleate or dodecylamine, AG-1 possesses a lower surface tension and a stronger ability in reducing the surface tension of gas-liquid interface, which can better improve mineral hydrophobicity.