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.

A kind of similar rock material was prepared with gypsum and quartz sand, and influence of seven factors on the strength index of the material was analyzed by performing laboratory tests. The results show that curing temperature and material density are in positive correlation with material strength index, while curing humidity, sand-to-binder ratio, ash-to-paste ratio, fine-grained quartz sand content, as well as water content are in negative correlation with material strength index. Based on the calculation of the sensitivity indices of different influencing factors, it is found that material strength has a sensitivity of only 4.5% to curing temperature, a sensitivity of 104.9% to sand-binder ratio. Factors of curing temperature, water content, material density, curing humidity, ash-to-paste ratio, fine-grained quartz sand content and sand-to-binder ratio are in an ascending order in terms of their sensitivity to uniaxial compressive strength; while factors of sand-to-binder ratio, ash-to-paste ratio, material density, curing humidity, water content, fine-grained quartz sand content and curing temperature are in a descending order in terms of their sensitivity to tensile strength.

The phase composition and morphology of a molten mixture of steel slag and furnace slag prepared at a high temperature was analyzed by X-ray diffraction and SEM-EDS scanning electron microscope to investigate the effect of MgO doping. The results show that MgO doping can effectively inhibit the formation of MgFe₂O₄ phase and non-gel Ca₂Al₂SiO₇ phase, and promote the formation of MgFeAlO₄ phase, thus increasing the melting point of the mixed slag. It is found that the mixed slag after doping 2% MgO presents a layered structure on its cross section. The inner layer has an increased proportion of MgFeAlO₄ phase, with uniform and fine pores; and the MgFeAlO₄ phase is wrapped by MgFe₂O₄ spinel with layered structure in the middle part; and the outer layer has Ca₂Al₂SiO₇ phase with uniform pores and moderate density. The mixed slag with such kind of structure is suitable to be used as the filter material for removing heavy metal ions.

By using CFD-DEM coupling approach and Archard wear model, a slurry pump with small flow was numerically simulated under the conditions including different flow rates and particle sizes. Based on the analysis of the movement law of particles in the pump, the distribution of particles in different regions of pump and the collision between particles and wetted parts of the pump, the wear characteristics of wetted parts in the slurry pump, especially the volute were studied. The results show that there is some blockage in the volute approaching the tongue region due to a slow flow rate of particles. It is found that wear of the volute is mainly concentrated on the upper part and near the tongue region. With the increase in the flow rate and velocity of particles, the kinetic energy of the particles collide with the pump wall increases, resulting in serious wear on the body of slurry pump. And the wear will become more serious by the particles with small grain size.

An experimental study was carried out for sulfur reduction and upgrading of a high-sulfur antimony-gold bulk concentrate from Russia with Sb grade of 24.58%, Au content of 76.92 g/t and S content of 14.46%. A closed-circuit flotation test was conducted using a new collector CJ-201 and a new depressant CJ-5S. The Sb and Au grades in the antimony concentrate attained respectively 42.26% and 92.36 g/t, with the corresponding recoveries of 88.04% and 62.18%. With this approach, a antimony-gold concentrate product with high content of antimony and low content of sulfur can be separated out from antimony-gold bulk concentrates collected in a Russian mine.

Aiming at complicated flow field of Y-shaped pipe in pump piping system and risk of ore leakage in conveying test for deep sea mining, numerical simulation was performed by using CFD-DEM method for ore particles with different velocities, different volume concentration and different particle sizes. Based on that, the movement features of particle groups and flow field distribution pattern in Y-shaped pipe were all analyzed. It is found that the flow field distribution in Y-shaped pipe is influenced by the curvature of pipe elbow and the flow distribution in the inlet of Y-shaped pipe. The particle groups flow against the inner wall of elbow, and deflect upward under the influence of upward flow. If upward flow with lower velocity, particles with large grain size and high volume concentration will hit the bottom of pipe, leading to some losses. As the upward velocity decreases and both particle volume concentration and grain size increase, more and more particles will be continuously lost on the bottom of pipe. Due to the existence of particle flow, both intensity and scale of the low-pressure vortex region in Y-shaped pipe become weaken.

With sodium bicarbonate as a precipitant, praseodymium neodymium oxide was prepared by feeding step by step in a positive sequence. The effects of pH value at the end of precipitation and precipitation temperature on particle size and impurity content of the precursor and product of praseodymium neodymium oxide were all investigated. The results show that precipitation at 50 ℃ with pH value of 5.10 at the end can prepare a praseodymium neodymium oxide powder with a median particle size D₅₀ of 21.45 μm and narrow particle size distribution. It is sphere-like powder formed by flake crystallization agglomeration, with the content of Cl^-and Na₂O at 0.017% and 0.012%, respectively, indicating higher than the national standards.

A Fe-based cladding layer was prepared on the surface of 27SiMn steel by using laser cladding technique, and effect of preheating on the microstructure and mechanical properties of the heat affected zone (HAZ) of 27SiMn steel was investigated. The results show that a large amount of martensite appears in the HAZ of 27SiMn steel after laser cladding process. The tensile fracture is composed of river-pattern cleavage plane, tear edge and dimple, representing a quasi-cleavage fracture; preheating treatment effectively reduces the amount of martensite and brings pearlite structure. When the preheating temperature is 100 ℃, the quenched layer has its hardness decreased by 25.4%, elongation increased by 11.5%, and tensile strength decreased by 14.3%. When the preheating temperature rises to 300 ℃, ductile fracture occurs in the material under tensile force. Appropriate preheating can effectively reduce the martensite in the HAZ of 27SiMn steel and alleviate the decline in the toughness of 27SiMn steel caused by quenching, thus improving the safety during the service of hydraulic cylinder made of laser cladded 27SiMn steel.

A technique combining mechanical force and heating effect was adopted to selectively disassociate cathode material from spent lithium-ion batteries and roll the aluminum foil by adjusting processing parameters. The results show that a better disassociation effect can be obtained with the frequency of electric motor, air circulation fan and dissociation device at 40 Hz, 40 Hz and 50 Hz, respectively. The aluminum foil with particle size of -1.7+0.075 mm is rolled to be spherical, and the cathode materials with particle size of -0.075+0.048 mm and -0.048 mm are rough on the surface and wrapped by organic binder. The final dissociation rate of cathode sheet can be up to 96.35%, and the cathode material can be recovered at a rate of 94.95% by single operation, with the content of Al impurity less than 0.15%. It is shown that this selective dissociation technique based on a combination of mechanic force and heating effect can actualize an efficient separation and sorting of cathode sheet, not only shortening the battery disposal process flow but also achieving efficient metal enrichment.