After an introduction of the current status of gallium resources and analysis of the occurrence state of gallium in sodium aluminate solution, zinc smelting slag, tailings from vanadium extraction and coal-based solid waste, progress in the research of gallium extraction processes is elaborated and the adaptability, advantages and disadvantages of each technique are also summarized. Finally, based on the discussion of problems faced by the gallium industry and the development direction in the future, it is suggested that iteration and upgrading of gallium extraction processes should be vigorously promoted based on China's scale advantage in alumina industry.

In combination with experiments and multi-step finite element simulation, the residual stress distribution in components manufactured by laser powder bed fusion (LPBF) and the influence of the initial residual stress field on the laser shock peening (LSP)-induced compressive residual stress field. The validity of the simulation results was verified by the residual stress values measured with X-ray diffraction. The results show that the thermal stress of the lower and middle layer materials in the component fabricated by LPBF undergoes a transition from zero stress, compressive stress, tensile stress to compressive stress, while the top layer material shows a transition from zero stress, compressive stress to tensile stress, thus leading to tensile residual stress occurred on the surface layer of LPBF fabricated component, while compressive residual stress in the lower part. The action of initial residual stress field results in the reduced peak value but increased depth of LSP-induced compressive residual stress. The initial residual tensile stress field of LPBF components can exert a suppressive and dragging effect on the reverse plastic deformation caused by surface waves, leading to reduced intensity and changed position of the “residual stress hole”, which can improve the uniformity of LSP-induced residual stress distribution.

Based on flotation tests of a low-grade copper sulfide ore, a processing technique was developed, composed of flash flotation of Cu, Cu-S bulk flotation, and Cu-S separation after regrinding of roughing concentrate from bulk flotation. Effects of factors on flotation were also explored, including grinding fineness, flotation reagent, regrinding fineness of roughing concentrate from bulk flotation. Ammonium dibutyl dithiophosphate was used as the collector for Cu in the flash flotation, a combination of ammonium dibutyl dithiophosphate and butyl xanthate as the collector for Cu-S bulk flotation, lime as a sulfur depressant, and terpineol oil as a frother. With grinding fineness of -0.074 mm 60% and regrinding fineness of -0.045 mm 70%, a closed-circuit test for the raw ore assaying 0.40% Cu and 2.45% S produced a bulk copper concentrate grading 19.49% Cu at 87.68% recovery, and a sulfur concentrate grading 48.65% S at 35.11% recovery. It is concluded that efficient separation and enrichment of copper and comprehensive recovery of sulfur from this low-grade copper ore can be actualized by this technique.

Heavy metal pollution in Dalong River was assessed by field sampling and detection analysis. Hg(II) and Pb(II) in the water and sediment were adsorbed with sludge-derived biochar for ecosystem restoration in Dalong River, and the restoration effect was then compared with that by using activated carbon. The results indicate that heavy metal pollution in Dalong River is relatively slight, and the contents of heavy metals in the surface water at all sampling points are within a safe range, only the sediment at some sampling points has the heavy metal pollution at a light pollution level. It is shown that sludge-derived biochar has a good adsorption for Hg(II) and Pb(II), with the adsorption process conforming to the Langmuir isotherm (with R² of 0.932 2 and 0.998 9). Compared with activated carbon, the sludge-derived biochar can bring better restoration effect, and its desorption of Hg(II) and Pb(II) also shows that it can have a significantly better fixation effect of heavy metals.

Based on an overview of progress in the research on iron recovery from high-iron red mud by alkaline electrolysis, the research findings at home and abroad are introduced in terms of principle and advantages of electrolysis, influencing factors for the process, and the obtained iron products. The advantages of red mud in the process for preparing metallic iron by electrolytic reduction of red mud in alkaline media at low temperatures are elaborated, and some problems to be solved in the future are proposed, which can provide references for innovation and development of this process.

The tailings from gravity separation of cassiterite in a polymetallic ore from Guangxi Zhuang Autonomous Region were taken for experimental research. Due to its low grade, fine particle size of target minerals therein and similar floatability of tourmaline and cassiterite, a multiple ligand metal-group collector, CSC-BHA-Pb, and a high-efficiency depressant, XY1, were adopted to selectively inhibit gangue minerals dominated by tourmaline while efficiently enrich fine-grained cassiterite. On the basis of iron removal and desulfurization, an open-circuit flotation test of cassiterite, consisting of one roughing, one scavenging and seven cleaning, finally produced a tin concentrate with a Sn grade of 14.05% and a recovery of 28.79%, achieving efficient tin enrichment.

Homogenization of backfill slurry cannot be automatically evaluated during stirring process. To solve this problem, the Yolo-v7 algorithm was improved by using the CBAM and the SPD-Conv, and the improved Yolo-v7 algorithm was then employed to automatically evaluate the homogenization of backfill slurry. The research results show that the improved Yolo-v7 algorithm demonstrates a significantly improved performance, with the accuracy, recall rate and mean average precision (mAP) all increased by 17.5, 28.8, and 32.4 percentage points respectively. Analysis of slurry parameter sensitivity indicates that slurry concentration is the principal factor affecting evaluation of slurry inhomogeneity, followed by the cement-tailings ratio. Moreover, the homogeneity of backfill slurry with high concentration can be significantly improved by prolonging stirring time.

An experiment was carried out on treating high-salinity wastewater by air gap membrane distillation (AGMD). Effects of different operating conditions on the performance of AGMD were investigated, and membrane fouling and its control measures were also analyzed. It is shown that the permeation flux increases with the increase of temperature and flow rate of feed, and decreases with the increase of cooling water temperature and salt concentration. The salt rejection rate can maintain above 99.8% with the salinity less than 60 g/L, and still exceed 90% with salinity within the range of 60－100 g/L. It is concluded that AGMD technology can be adopted to treat high salinity wastewater.

With bamboo as a raw material, different hard carbon materials were prepared by different impurity removal processes, and the effects of those processes on the impurity content, physical structure and sodium storage performance of hard carbon were explored. The results show that after impurity removal treatment, the bamboo-derived hard carbon has reduced impurity content and specific surface area, and increased interlayer spacing. With the preparation cost and the sodium storage performance of hard carbon comprehensively taken into consideration, acid leaching is chosen as the impurity removal process for hard carbon. It is shown that at a current density of 30 mA/g, the anode material with prepared hard carbon can have an initial Coulombic efficiency of 83.87% and a reversible specific capacity of 308.96 mAh/g；it demonstrates a capacity retention rate of 96.57% after 100 cycles at a current density of 300 mA/g, showing excellent sodium storage performance.

An experimental study was carried out for mineral processing of a Cu-S ore with grade of MgO at 11.86%, grade of S at 6.81%. In the experiment, a flotation process, consisting of preferential flotation of copper, Cu-S separation and reverse flotation of copper concentrate for removal of magnesium, was adopted, with SG-2 as a copper collector in combination with HD as a depressant for magnesium-containing gangue, producing a standard copper concentrate grading 23.47% Cu and 2.99% MgO, with copper recovery at 81.10%.