The concentration of plume caused by hydraulic collecting system during deep-sea polymetallic nodules mining under different working conditions were analyzed. Test results show that the concentration of discharged plume from conveying system is much higher than that of sediment plume caused by the disturbance of capture system, which is one of the main causes of turbidity current in the sea. In the test, the curve of slurry concentration presented a steep upward trend line followed by a steep downward line. Increasing oil pressure of the pump of capture system will lead to higher concentration of slurry. However, the oil pressure of the pump of conveying system won't result in obvious variation in slurry concentration.

The spent cathode carbon block after aluminum electrolysis was treated by acid leaching with a mixed solution of sulfuric acid and ammonium sulfate, and the effects of factors, such as molar ratio of sulfuric acid to ammonium sulfate, liquid-solid ratio, leaching temperature and time, on the leaching rate of cryolite from this spent cathode carbon sulfate were investigated. The results show that at a leaching temperature of 70 ℃, with liquid-solid ratio of 8 mL/g, sulfuric acid and ammonium sulfate in a molar ratio of 4, a 120-min leaching process can lead to the leaching rate of cryolite up to 99.48%. The leaching residue, being composed of carbon and calcium fluoride and free of leaching toxicity, can be treated as a general solid waste.

Experiments of roasting and leaching of some sulfur concentrate were performed, and the effects of two schemes with fixed bed roasting and fluidized bed roasting on gold extraction were analyzed. The results showed that with the sulfur concentrate at a sizing of 80% -0.074 mm, the proper conditions for a fixed bed roasting included a roasting temperature of 650 ℃ and roasting time of 4 h; while the proper conditions for a fluidized bed roasting included a roasting temperature of 650 ℃ and roasting time of 3 h, roasting gas and material in a ratio of 2.1 m³/kg. The calcines obtained by these two roasting methods were then separately leached for 24 h with the slurry concentration of 33% and pH of 11.5, 2 h alkali treatment and CG505 dosage of 10 kg/t, resulting in the leaching rate of gold reaching 69.45% and 69.92% respectively. It is shown that the fluidized bed roasting can bring in a better gold extraction result. This research results can provide a technical basis for recovery of valuable elements from sulfur concentrate.

The west slope of SCM copper cobalt mine in DRC was taken as an example for determining the shear strength parameters of rock mass by a laboratory triaxial compression test, back analysis of landslides, evaluation of rock mass quality and strength conversion with Hoek-Brown criterion, and then the obtained strength parameters were verified. The results show that due to the size effect of the samples, there may be deviation in the cohesion of rock mass shear strength obtained from the laboratory triaxial compression tests. It is found that with the obtained parameters used in slope stability analysis, more accurate evaluation results can be obtained from the slope model with higher sensitivity to friction angle, while lower accuracy from the slope model with higher sensitivity to cohesion. Under the same working condition, the parameters of slope rock mass obtained from the back analysis of shallow landslides can be used for analyzing local or single bench stability, and the parameters of slope rock mass from back analysis of deep-seated landslides or the landslides due to weak structural planes can be used for overall stability analysis. It is found that the shear strength parameters obtained based on Hoek-Brown failure criterion are close to the results from laboratory triaxial compression test, also easy to operate and more accurate, which can have a wide application.

An accumulative bauxite ore in Yunnan containing 42.13% Al₂O₃, 15.73% SiO₂ and 17.44% TFe, namely, with an Al/Si ratio of 2.68, was taken in a flotation for Al/Si separation, and the effects of pH regulator dosage, type and dosage of depressant, collector dosage and grinding fineness on desilication performance of flotation were all investigated. A closed-circuit flotation test performed with the optimized parameters produced an aluminum concentrate with Al₂O₃ grade and recovery of 52.16% and 70.30%, Al/Si ratio of 7.69, and TFe grade of 20.89%, respectively. Then, a flowsheet consisting of magnetic roasting and magnetic separation was introduced to treat this aluminum concentrate for Al/Fe separation, which produced a final aluminum concentrate containing 69.34% Al₂O₃ with Al/Si ratio of 8.70, and a rough iron concentrate grading 52.34% TFe with a process recovery of 76.03%.

In order to find a more accurate and efficient way to measure volume of explosion-produced craters, the traditional method by using a reference plane with a vertical section was improved. Taking the crater produced by single-hole blasting of the deep orebody in Gaofeng Mine as an example, the measurement result by using 3D laser scanning was compared to that by using a reference plane with a vertical section. It is found that 3D laser scanning measurement is superior in terms of accuracy, efficiency and measuring operability. This research can provide a new idea for accurately measuring the volume of explosion-produced craters.

With laser high-energy beam as heat source to initiate exothermic reaction, Cu-Al powder was compacted and sintered into Cu-Al alloy containing in-situ formed hard reinforcing phase Al₂O₃ by laser-induced self-propagating synthesis. The effect of Cu-Al ratio in the composition on the microstructure and properties of alloy system was explored. The results show that the microstructure of Cu-Al alloy is a multiphase structure composed of hard reinforcing phase Al₂O₃ and matrix of CuAl₂, AlCu₄, Al₄Cu₉ and other intermetallic compounds. The alloy has rich dendritic crystals in microstructure, and becomes more uniform and fine-grained with the increase of aluminum content. Increasing the content of aluminum to a certain range is helpful to improve the compactness of sintered products. With copper and aluminum in a mass ratio of 33.2∶66.8, the sintered product has the lowest porosity (10.57% ), the highest microhardness (373HV) and the best wear resistance (with wear rate of 0.137 g/mm²).

Microseismic signals collected during roadway construction in Jinfeng Gold Mine in the southwest Guizhou Province are non-stationary and also contaminated with background noise. For solving this problem, a noise reduction method based on the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) combined with blind source separation (BSS) was proposed. With this method, a microseismic signal can be preliminarily decomposed by ICEEMDAN algorithm, and then correlation coefficient and marginal spectrum of signal can be calculated with MATLAB. Components of noise-containing mode and main frequency of signal can be filtered, and FastICA algorithm is finally used for BSS to achieve noise reduction. The practical application in mine shows that compared to empirical mode decomposition (EMD) and traditional wavelet packet threshold method, the proposed method, with higher signal-to-noise ratio (24.142 5 dB), can bring better noise reduction effect with smaller standard error (0.012 18).

The interaction mechanism of kyanite group minerals and quartz in cationic flotation system was studied by using an extended DLVO (EDLVO) theory combined with microscopy analysis. The results show that, under conditions including pH value of 8, FeCl₃·6H₂O dosage of 30 mg/L and dodecylamine dosage of 80 mg/L, there is interaction between quartz and kyanite group minerals in various size fraction, and the adhesive coating among particles is one of the main reasons for the interaction between kyanite group minerals and quartz amidst flotation process. Besides, the adsorption force between kyanite group minerals and quartz is in the following descending order：andalusite/quartz ≥kyanite/quartz ≥ sillimanite/quartz, indicating that it is relatively difficult for andalusite to be separated from quartz by flotation.

In order to explore disturbance of seabed sediment during mining of polymetallic nodules, a pool experiment was carried out to scour sediment by a waterjet from polymetallic nodules collector. Variation of gully depth, and migration and diffusion regulation of sediments were investigated in the experiment by setting the waterjet at different speed, with nozzle at different height from sediment, and collector at different traveling speed. The results show that the collecting process of polymetallic nodules brings scour to both particles and blocks of sediment, leading to uneven surface of the gully. Then, disturbed sediment migrates and diffuses through upper plume flow and bottom gravity flow.