To explore feasibility of replacing steel ball with porcelain ball in the second-stage grinding of a magnetite ore from Anhui, the feed ore to the second-stage grinding process in the magnetite ore processing plant was taken for study, and single-factor tests were conducted for gradation of porcelain ball in diameter, grinding concentration and filling rate of grinding media. On this basis, researches on grinding kinetics and commercial application were also conducted. The results show that porcelain ball can substitute steel ball as the medium in the second-stage grinding, which can bring in optimized particle size distribution of the milled product. For the feed in a particle size greater than 0.092 mm, the grinding rate of porcelain ball milling is greater than that of steel ball milling；while with the feed in a particle size less than 0.092 mm, the grinding rate of porcelain ball milling is less than that of steel ball milling. The best conditions for porcelain ball milling are finally determined as follows: porcelain balls with diameter of 30 mm, 25 mm and 20 mm in a mass ratio of 1∶3∶1, grinding concentration of 74% and grinding media with filling rate of 40%. The industrial applications with porcelain ball in mill shows the particle size distribution of overflow products can be effectively improved, both unit power consumption and ball consumption reduced by 51.89% and 50%, respectively.

An experimental study was performed on efficient separation of talc and molybdenite by adopting flash flotation. With grain fineness of 0.043-0.074 mm, 20 g/t of frother MIBC, and flotation time of 60 seconds, the talc recovery attains 76.64%, while the recovery of molybdenite is only 19.72%, resulting in an efficient separation between talc and molybdenite. According to the nonlinear fitting of flotation kinetic equation by MATLAB, talc flotation process conforms to the classic first-order flotation kinetic model, while molybdenite flotation conforms to the modified classic first-order flotation kinetic model. The following test on the influence of flotation time on adsorption of MIBC on talc and molybdenite shows that talc is more likely to interact with the agent than molybdenite at the early stage of flotation, and much more MIBC is adsorbed on talc than on molybdenite at that stage.

In order to address the problem of slope stability for a valley dumpsite in one mountain area, numerical simulation was conducted with FLAC^3D for the stability of slope under three working conditions, including natural state, rainstorm case and earthquake occurrence. The stability and reliability of the dump under conditions of rainstorm plus seismic was evaluated with introduced Monte Carlo algorithm. Results show that the overall and part of dumpsite slope, under all three working conditions of natural state, rainstorm and earthquake, can be in a stable state, and the overall safety factors present a normal distribution and are mainly within the range of 2.0-2.1, consistent with the numerical simulation results (2.08); under conditions of rainstorm plus seismic, the probability for the overall dumpsite to be unstable is 0, while some parts of dumpsite have a 35.99% probability to be unstable. It is shown that the numerical simulation value and on-site monitoring result present a deviation from 9.8% to 15.4% based on the comparison.

Copper ore sorting by dual-energy X-ray technique basded on traditional algorithms by curve fitting of T-value always results in great deviation. In view of this problem, a curve fitting of T-value by segmented straight lines was proposed. This method divides thickness into several segments, and performs a T-value curve fitting in each segment for copper ore sorting, which can more accurately reflect the changing trend of T-value with different thicknesses and also reduce impact of thickness on sorting. High-energy and low-energy rays are adopted to fit the T-value curve, and then the residual between the T-value and the curve-fitting mapping value is calculated in each segment, showing different residuals for different substances, which can be used to achieve copper ore sorting. In a verification experiment, two types of copper ores with different grades were sorted by this method. The ore images fitted with T-value curves by segmented straight lines were put into ResNet18 neural network for training, and the trained model was then used for testing. The test results show that an accuracy rate can reach 88.67%.

According to the mineral properties of a kind of flake graphite ore in Heilongjiang Province, a new efficient flotation reagent was developed and then adopted in a flotation experiment. Results show that with the new reagent of CYM-11 as a collector, CYQ-01 as a foaming agent, an experiment with a closed-circuit flowsheet consisting of eight-stage regrinding and nine-stage cleaning can yield an graphite concentrate with fixed carbon content of 96.63% at 95.69% recovery, among which the graphite concentrate at a size of +0.15 mm can be produced with a yield of 11.38% and fixed carbon content of 96.04% in mass fraction. It is shown that the large flake graphite can be well protected during the course of mineral processing.

The effects of separate and combined usage of NaClO and KMnO₄ on the flotation separation of chalcopyrite and pyrite were investigated by performing flotation and adsorption tests, infrared spectroscopy (IR) and XPS analysis. The results show that selective separation of chalcopyrite and pyrite can be achieved with NaClO and KMnO₄ in a ratio of 10∶1, the total oxidant dosage of 70 mg/L, pulp pH of 10, and oxidation time of 3 min. It is shown that the recovery of chalcopyrite can exceed 92%, while the recovery of pyrite is less than 8%. The IR and XPS analyses show that a combined usage of NaClO and KMnO₄ obviously changes the surface property of pyrite, resulting in hydrophilic oxidized substances on the surface, such as iron oxide, iron hydroxide and iron sulfate, which impedes the adsorption of collectors, thus reducing floatability of pyrite. The chalcopyrite surface remains mildly inert to NaClO and KMnO₄ under certain conditions. Consequently, the adsorption of xanthate on chalcopyrite is remarkably higher than that on pyrite, which favors their flotation separation.

An experiment was carried out with a pelletizing and magnetization roasting process for fine-grained specularite to investigate the pelletizing process, as well as the roasting performance and effect of pellets in the process of magnetization roasting. The results show that by adopting a process of fine grinding and pelletizing followed by magnetization roasting with an additionally prepared reducing agent, under the condition of roasting at 810 ℃ for 60 min, and addition of charcoal at an amount of 2.5%, a concentrate grading 49.04% Fe at 76.99% recovery can be obtained. In comparison, with a process of direct pelletizing followed by 60 min magnetization roasting at 650 ℃ with additionally prepared reducing agent and addition of semi-coke at an amount of 3.0%, the concentrate grading 52.95% Fe at 85.07% recovery can be obtained. It is found that the processing technique consisting of direct pelletizing and magnetization roasting is simpler and can bring better processing indicators. It can provide a reference for on-site processing of fine-grained specularite by adopting magnetizing roasting.

A heap leaching test was carried out for the low-grade copper-cobalt oxide ores from Congo (DRC), and effects of spray intensity, spray acidity and ore particle size on the leaching rates of copper and cobalt were investigated. The results show that both acidity and intensity of spray bring significant impact to the speed and cumulative rates of copper and cobalt leaching, while the ore particle size has little effect on leaching process. And finally, the optimal conditions for heap leaching of low-grade copper-cobalt ore were determined, including spray acidity at 20 g/L, spray intensity of 15 L/(m²·h), and ore particle size of less than 40 mm. It is shown that the cumulative leaching rates of copper and cobalt can reach 90.89% and 82.27%, respectively, after 100 days of heap leaching.

The effect of water splat cooling assisted friction stir welding (WCaFSW) on the structure, texture and mechanical properties of aluminum alloy welding joints were investigated by means of optical microscopy, scanning electron microscopy and a tensile testing machine. The results show that compared to normal friction stir welding (FSW), WCaFSW can lead to grains in weld nugget zone (WNZ) with significantly reduced size and grains in all regions of WNZ with more uniform size, and a higher percentage of high-angle grain boundaries. The WNZ of FSW joints have and B shear texture, while the WNZ of WCaFSW joints have and C shear texture. Compared to FSW joints, WCaFSW joints have higher tensile strength and lower elongation rate. And ductile fracture is the main failure mode in both WCaFSW and FSW joints.

Based on the detailed process mineralogy study of a kind of refractory gold ore, an experimental research was carried out for gold extraction. It is found that the gold mineral in such ore are fine-grained and dispersed in gold-carrying minerals. It is proposed that such refractory gold ore be processed with the technique of enhanced flotation, and an addition of regulator XPT511 can effectively improve the index of gold flotation. It is shown that a close-circuit flotation test results in a gold concentrate grading 22.91 g/t Au at 62.85% recovery.