Processing parameters were optimized to improve the quality of a vanadium-titanium iron concentrate from Panzhihua-Xichang region. A process flowsheet of staged grinding followed by mineral separation was adopted, consisting of demagnetization, pre-classification with 0.074 mm fine screen, regrinding of +0.074 mm range particles to a fineness of -0.074 mm 92.85% followed by magnetic separation, and direct magnetic separation of -0.074 mm range particles. It is shown that the obtained iron concentrate can have its TFe grade upgraded by 3.19 percentage points, and the total content of SiO₂, Al₂O₃ and MgO therein reduced by 3.91 percentage points.

Interrupted quenching experiments were conducted to investigate the hardness (HV) and unit initiation energy (UIE) of 7N65 alloy samples at various temperatures with different hold time, and the relative TTP-HV and TTP-UIE contour diagrams were also plotted. The precipitation behavior of second phases at various temperatures was characterized by adopting scanning electron microscope and transmission electron microscope. The findings reveal that S-phase (Al₂CuMg) is the dominant grain boundary precipitate after the alloy is held at a temperature between 390 ℃and 450 ℃, and increases in grain size and numbers as hold time is prolonged. Thus the alloy has less fracture toughness and is prone to fragile fracture along with the broken grains. When the alloy sample is held at a temperature between 250 ℃and 390 ℃, precipitates at grain boundaries are predominated by η-phase (MgZn₂), which increases in the numbers and grain size as hold time is prolonged, leading to lower strength of inner grain, smaller difference in strength between inner grains and grain boundaries. Thus, the alloy has higher fracture toughness and is more prone to ductile fracture with more transgranular dimples.

A new directional core acoustic emission technique was used to measure in-situ stress of the gas storage reservoir construction area of the Zhangbei Comprehensive Energy Project in Hebei Province. Results show that three boreholes buried at depth of 90 m have the corresponding in-situ stress dominated by horizontal structural stress, with the maximum principal stress approximately in the same north-south direction. In addition, the circumferential wave velocity anisotropy analysis method was conducted for verification, and the results show that the maximum principal stress is in a direction consistent with the result obtained from the acoustic emission testing of borehole core, which further verifies the correctness of the measurement by acoustic emission technique for the borehole cores.

Calculation was made for four typical pipelines by adopting typical critical flow rate and frictional pressure drop calculation model. The precision of the model was analyzed by comparing the calculated value with the measured value of four pipelines. The results show that as for flow rate and pipe diameter, the calculated values from Wasp model, HAN Wenliang model, FEI Xiangjun model and LIU Dezhong model are in good agreement with the measured value, presenting the maximum deviation within the range of ± 15%. FEI Junxiang model presents higher precision in the calculation of frictional pressure drop, with the maximum deviation within the range of ± 10%, but also has certain margin in calculation. It is concluded that FEI Xiangjun model can provide an important basis and reference for the design of long-distance transportation.

The effects of different heat treatment regimes on the microstructure and properties of as-cast Mg-5Sn-1.5Al-1Zn-1Si alloy were investigated. The results indicate that during the dissolution of solid, as the dissolution time is prolongsed, the alloy dendrites gradually dissolve and the grains gradually spheroidize. It is shown that the appropriate dissolution parameter is 510 ℃ × 8 h, and the alloy after such treatment has an evenly distributed microstructure, with a trace of precipitation of fine second-phase particles from the matrix, and thus possesses a high elongation rate. The appropriate aging parameter for the alloy is 200 ℃ × 16 h, and due to precipitation and migration of the phases segregating at the grain boundary, the alloy after aging treatment possesses clear grain boundaries and a microstructure with high uniformity, and also has the yield strength up to 136.3 MPa, which is higher than that of the as-cast alloy by 16.5%. After a treatment including 8 hours of solid dissolution at 510 ℃ and 16 hours of aging at 200 ℃, the alloy has its uniformity and dispersion of the microstructure further improved, and its tensile strength and hardness reach to 178.2 MPa and 59.6HB, respectively, up by 21.6% and 23.4% compared to the as-cast alloy.

The influence of magnetite on bioleaching of chalcopyrite by Acidithiobacillus ferrooxidans was systematically explored by electrochemical tests such as open-circuit potential and cyclic voltammetry. Results show that the leaching rate of chalcopyrite can be increased by increasing the addtion of magnetite in the leaching system by undomesticated bacteria. The bacteria after domestication presents enhanced activity. With the addition of magnetite at an amount of 0.5 g, the copper leaching rate can be increased by around 8%. With the addtion of magnetite at an amout over 0.5 g, jarosite is generated during the leaching process, which can worsen the leaching environment, leading to the copper leaching rate just up by about 2%. The open circuit potential of chalcopyrite is always higher than that of magnetite in the system with different concentrations of Fe³⁺. During the galvanic reaction between chalcopyrite and magnetite, chalcopyrite acts as the cathode, which is not conducive to oxidation and dissolution of chalcopyrite. However, Fe³⁺in the solution can increase the corrosion rate of chalcopyrite, leading to an increased leaching rate of chalcopyrite.

A low-grade manganese carbonate ore in Tongren of Guizhou Province has complicated mineral compositions, with a higher content of clay mineral illite (19.30%). In order to improve the mineral dressing index of this type of manganese ore resources, magnetic separation experiments was performed for it by using a high gradient magnetic separator. In the experiment, the mineral after pre-desliming was ground by a ball mill to a grinding fineness of -75 μm 69.62%. Then, it was subjected to a magnetic separation process consisting of one roughing and two scavenging, resulting in the final manganese carbonate concentrate grading 19.39% Mn at 83.66% recovery, with yield of 52.81%. The experiment results are of great significance for reducing the discharge of electrolytic manganese slag in Tongren.

The composition structure and operation process of mini seafloor crawler drill are briefly introduced. A multi-body dynamic model of mini seafloor crawler drill was established by using Recurdyn software. And then, a mechanical model was established for seafloor sediment based on an experimental study on mechanical properties of sediment soil. Dynamic simulation was also performed for the motion of mini crawler drill on seafloor. Results show that mini seafloor crawler drill runs on seafloor sediment with slight slippage and an elevation angle due to a certain sinking of seafloor sediment. It is found that the dynamic characteristics of mini seafloor crawler drill is significantly influenced by the mechanical properties of sediment (especially thin and soft sediment), and mini seafloor crawler drill running at a lower speed will bring greater influence to its dynamic characteristics.

In an experiment for Cu/Mo separation of a copper-molybdenum bulk concentrate, ozone oxidation technique was applied to enhance floatability difference between chalcopyrite and molybdenite. Under adequate ozone oxidation conditions, a molybdenum concentrate grading 47.46% Mo at 94.96% recovery, with Cu content of 0.10% can be obtained from a closed-circuit flotation test adopting a flowsheet consisting of one stage of roughing and three stages of cleaning. It is shown that the flotation indicators obtained by applying ozone oxidation technique is superior to that by using Na₂S as the depressant, which indicates that the ozone oxidation technique can be used to substitute Na₂S depression approach for Mo flotation whilst depressing Cu.

In order to explore the reliability of type selection in the design of lift pipe for underwater transport system in deep sea mining, hydrodynamic parameters were checked with transport indices as input for design. Based on the settling velocity of polymetallic nodules, anti-fatigue threaded sleeve of P110 steel, with outer diameter of 244.48 mm and wall thickness of 20.24 mm, was selected for lift pipe. And a towing test performed in a pool shows that the resistance drag coefficient is 1.4 for the lift pipe at the upper end of the pump and 1.3 at the lower end of the pump. Hydrodynamic parameters were calculated and analyzed for the underwater transport system according to working conditions and launching conditions, showing that the safety factor of lift pipe can meet the requirements of API RP 2RD Standard. In the deep-sea polymetallic nodules mining test project, lift pipe in the at-sea acceptance test, with reliable joint connection, could meet the requirement for each transporting parameter, which has verified that the type selection of lift pipe in the design is acceptable.