The ultra-fine low-grade calcite-containing apatite concentrate that comes from Hebei Province cannot meet the grade requirement and is difficult to be utilized. For solving this problem, an experimental research was carried out to improve the concentrate grade. A depressant of CD-8 was adopted for calcite, the dominate gangue mineral affecting the grade of apatite concentrate, and a collector of CK-P with high selectivity was adopted for apatite. A closed-circuit experiment was performed with a direct flotation flowsheet, consisting of one roughing, one scavenging and three cleaning, with middlings sequentially returned. As a result, a phosphate concentrate with P₂O₅ grade of 32.02% was finally obtained with a recovery of 70.92%. This flowsheet was applied to industrial production with normal operation and stable flotation indicators, indicating that efficient utilization of such ultra-fine and refractory phosphorus resource was actualized.

As for the leaching solution of gold with copper(II)-ethylenediamine-thiosulfate, an adsorbent (TTAB@Sch) was prepared by modifying schwertmannite (Sch) with tetradecyltrimethylammonium bromide (TTAB), and applied to adsorb arsenic therein. The effects of Cu²⁺ concentration, ethylenediamine concentration, S₂O₃^2- concentration, solution pH and initial arsenic mass concentration on the adsorption of arsenic by TTAB@Sch were explored. The results show that with the addition of FeSO₄·7H₂O, KMnO₄ and TTAB at amounts of 10, 1 and 2 g/L respectively, the prepared TTAB@Sch exhibits optimal adsorption behavior. As for the leaching solution with Cu²⁺ concentration of 5 mmol/L, ethylenediamine concentration of 12.5 mmol/L, initial arsenic mass concentration of 12.29 mg/L, and pH of 10, the adsorption rate of arsenic therein by TTAB@Sch can reach 87.2%. Furthermore, FT-IR and XPS analyses indicated that arsenic was likely adsorbed on TTAB@Sch by forming Fe—O—As.

By means of computational fluid dynamics simulation technology, the particle flow behavior in a XFD flotation machine was simulated with Euler's method, and the effects of impeller speed and particle size on the distribution characteristics in a solid-liquid two-phase flow field were explored to reveal fluid motion behavior in the flotation machine. The flotation kinetics of the flotation machine was also explored in terms of velocity field and turbulence intensity. The simulation results show that with a rotating speed at 1 800 r/min, the liquid-phase flow moves at a maximum speed of 5.32 m/s, and the fluid motion velocity and kinetic energy of turbulent are higher in the rotor zone and the lower circulation zone. The flow field is relatively stable, which is suitable for mineral flotation separation. The particle size of fine-grained minerals has a minor influence on the solid-liquid two-phase flow characteristics in the flotation machine, and the pressure distribution of the rotor surface is closely related to the particle size. It is found that the kinetic energy of turbulent is significantly enhanced in the region between the stator and rotor, which can effectively promote the dispersion of hematite particles. In a hematite flotation test, the variation in concentrate grade and recovery obtained with different rotation speed of impellers was studied. It is shown that with impeller rotating at a speed of 1 800 r/min, an iron concentrate with Fe grade of 66.35% and recovery of 85.34% can be produced. Based on the simulation of flow field of flotation machine, it is concluded that an impeller with a rotating speed of 1 800 r/m is suitable for flotation operation.

Wavelet analysis was performed for the collected pressure signals of gas-liquid two-phase flow in a vertical pipe in an air lift test. The optimal wavelet basis functions were determined by improving the signal-to-noise ratio (SNR). The range of decomposition levels was determined based on changes in energy of detail coefficients, and optimal decomposition levels were determined by the entropy weight method together with SNR, root mean square error and smoothness. After denoise with wavelet thresholding, three-level decomposition of signal was performed with the wavelet packet method, and then flow patterns were identified for gas-liquid two-phase flow with the energy ratio in the 1st and 2nd frequency bands and entropy values as feature vectors. The flow pattern recognition based on 389 sets of pressure signals shows that the extraction feature vector combined with random subspace decision tree can efficiently identify and classify gas-liquid two-phase flow patterns, and the overall mean recognition rate is up to 98.08% by adopting the improved wavelet thresholding.

The effect of vacuum hot-pressing sintering time on phase composition, microstructure, and densification of Al-30%Sc aluminum alloy were investigated using X-ray diffraction, scanning electron microscopy and electron backscatter diffraction. Results show that after a sintering process at 630 ℃ under 30 MPa, the prepared alloy samples exhibit good uniformity. As sintering time prolongs, the content of Al₃Sc phase in the alloy decreases but the content of Al₂Sc phase increases, and the density and grain size remain virtually unchanged.

As for the slope collapse at bench merging section in an open-pit mine, engineering geological analysis, analysis with stereographic projection and mechanical analysis were employed to comprehensively explore the main factors inducing slope collapse. Based on the causes and instability characteristics of slope collapse, a management scheme was proposed and thoroughly demonstrated. The results show that the collapse of bench slope occurs under the combined effects of rainfall infiltration and excavation at bench merging section, and induced effects of rock mass properties and weathering fracture surfaces. A management scheme of “gravity retaining wall foot pressure + gravel soil backfilling + shotcrete and rock bolt support” was proposed. The overall stability coefficient of the slope after management is 1.39, meeting the safety standard requirements.

To address issues such as land occupation and environmental hazards caused by stockpiling residues that are left after vanadium extraction from stone-like coal in the Western Hunan, a resource utilization scheme involving deep separation of carbon and ash was proposed. Firstly, coarse-grained minerals with ash content more than 94% were obtained by sieving, and the fine-grained undersize minerals were then subjected to flotation. A closed-circuit flotation test produced a concentrate with fixed carbon content of 32.86% and a higher heating value of 9 832 kJ/kg, which could meet the calorific requirement for the coal added in boilers. The recovery of combustible matter was 73.50%, while the obtained tailings had an ash content of 96.14%, with a yield of 78.42%, and the loss on ignition was 4.98%. The toxicity test confirmed that hazardous components in the high-ash tailings did not exceed limits. Based on preliminary economic estimates, it is concluded that this technical approach is economically feasible.

As for backfill slurry transported through reducing bends, the effect of bend angle, inlet flow velocity, mass fraction and average particle size of slurry, mass flow rate, particle shape factor and particle impact angle on the erosive wear of reducing bends were analyzed with Fluent software. The results show that the inlet flow velocity of slurry exerts the most significant impact on the erosion-prone areas of pipeline. With the inlet flow velocity up from 0.8 m/s to 2.0 m/s, the erosion rate in the erosion-prone areas of the pipeline surges approximately 43 times. The average particle size of the slurry ranks second in terms of its impact on the pipeline's erosion-prone areas, while the bend angle and particle impact angle have relatively minor effects. It is found that the erosion rate in pipeline is related to the kinetic energy of slurry；the greater the kinetic energy of the slurry, the more severe the erosion. The erosive wear locations of pipeline are primarily distributed at the inlet, the inner and outer wall surfaces of the bend, and reducing section and the straight section to the elbow, with the connection between the reducing section and the outlet section worn most severely.

A processing technique consisting of flotation, low-intensity magnetic separation (LIMS) and high-intensity magnetic separation (HIMS) was proposed for recycling blast furnace dust. With kerosene as a collector and zinc sulfate as a depressant, a flotation process consisting of one roughing and two cleaning was adopted firstly for decarbonization. Then, the obtained tailings were processed by LIMS followed by HIMS to obtain an iron concentrate, and the zinc concentrate was produced as the magnetic separation tailings. The full flowsheet test produced a carbon concentrate grading 86.16% C at 88.74% recovery, an iron concentrate (LIMS concentrate) grading 55.75% Fe at 67.01% recovery, and a zinc concentrate grading 16.79% Zn at 75.74% recovery. The migration patterns of main elements during the whole separation process were analyzed by using XRD and SEM-EDS. It is found that iron concentrate is mainly magnetite, and zinc concentrate is mainly zinc oxide. The lost zinc minerals left in the iron concentrate are mostly ZnFe₂O₄ in dispersed distribution. Besides, some processing technique and product schemes are also proposed for the obtained difficult-to-treat HIMS concentrate.

A novel low-temperature collector was adopted in the reverse flotation of Qidashan iron ore. Based on a reverse flotation condition test at low temperature, closed-circuit reverse flotation tests at room temperature and low temperature, as well as the study on the mineral adsorption mechanism, it is found that under conditions including pulp temperature at 10 ℃, pH of 11.0, caustic starch as a depressor at an amount of 600 g/t, CaO as an activator at an amount of 750 g/t, CH collector at an amount of 1 050 g/t, and pulp density of 30%, the reverse flotation consisting of one stage of roughing and one stage of cleaning can produce an iron concentrate grading 68.32% Fe at 70.76% recovery；the closed-circuit tests by adopting a process consisting of one stage of roughing, one stage of cleaning and three stages of scavenging at 10 ℃ can yield an iron concentrate grading 66.32% Fe at 85.14% recovery；while the close-circuit test at room temperature (25 ℃) results in 85.45% Fe recovery into an iron concentrate grading 67.31% Fe. It has proven that CH collector can bring good flotation effect at low temperatures. Infrared spectroscopy analysis, quartz contact angle testing and surface tension measurements indicate that CH collector has a stronger adsorption on quartz surfaces compared to traditional anionic collector sodium oleate.