A surfacing layer of Babbitt alloy was prepared on the surface of steel 20 by cold metal transfer (CMT) welding. And the metallographic morphology, phase composition, microstructure, element distribution, hardness and friction coefficient of the surfacing layer were analyzed by using metallographic microscope, X-ray diffractometer, scanning electron microscope, energy dispersive spectrometer, Vickers hardness tester, as well as friction and wear tester. The results show that the phase structure of surfacing layer of Babbitt alloy does not change and is composed of hard point SnSb phase, Cu₆Sn₅ phase and soft matrix α-Sn phase. A lower heat input leads to a rapid cooling rate for the surfacing layer of Babbitt alloy, and the surfacing layer with a finer grain size has hardness around 40HV_0.1, much higher than that of cast Babbitt alloy. As the microhardness increases, the friction coefficient and specific wear rate of Babbitt alloy fall down to 0.31 and 1.38 × 10^-5 mm³/(N·m), respectively. Based on the study of the wear mechanism, it is found that the surfacing layer of Babbitt alloy principally experiences abrasive wear. CMT welding can effectively improve the hardness and wear resistance of Babbitt alloy.

The cap specimens of Al_0.4 CoCrFeNi high-entropy alloy were dynamically loaded with a split Hopkinson pressure bar at room temperature, for studying the adiabatic shear sensitivity of Al_0.4CoCrFeNi high-entropy alloy at different strain rates. The results show that the grain size of Al_0.4CoCrFeNi high entropy alloy before and after dynamic loading is about 100 μm and 100 nm, respectively, with about three orders of magnitude difference. The Al_0.4CoCrFeNi high entropy alloy, with a finer grain size after dynamic loading, has lower adiabatic shear sensitivity, which will increase with the increase of strain rate. Within the range in the experiment, the adiabatic shear sensitivity reaches the highest when the strain rate is 3 360 s^-1, forming an adiabatic shear band that is about 2 μm wide and has an angle of 45° with the dynamic loading direction. At this moment, both the critical strain value and the formation energy per unit volume of adiabatic shear are the smallest. The Al_0.4CoCrFeNi high-entropy alloy undergoes significant grain refinement during high strain rate deformation. And the adiabatic shear of Al_0.4CoCrFeNi high-entropy alloy under dynamic loading is attributed to the thermal-viscoplastic constitutive instability of the material.

A mineral liberation analysis (MLA) automatic measurement technology was used to not only analyze the composition and dissemination of minerals in a skarn copper ore, but also investigate the characteristics like particle size distribution and mineral liberation degree of raw ore and bulk concentrate samples ground to different fineness. After a preliminarily study on beneficiation technique for such ore based on the obtained results, a processing flowsheet comprised sequentially of grinding, Cu-Pb bulk flotation, regrinding of roughing concentrate and Cu/Pb flotation separation. It is shown that such flowsheet with the primary grinding fineness of -74 μm 70% and the regrinding fineness of -20 μm 75% can produce a copper concentrate grading 20.88% Cu at 70.42% recovery, and 183.9 g/t Ag at 76.78% recovery, as well as a product of sulfur concentrate grading 32.65% S at 91.47% recovery.

Experiments were performed in a tube furnace for reduction roasting of high-iron manganese oxide ore, respectively with gas-based (CO) and pulverized coal as reducing agents. The effects of roasting temperature and roasting time on the simultaneous reduction of manganese and iron oxides therein were investigated. The results show that during the gas-based reduction roasting, the reduction process of Mn₂O₃ is controlled by chemical reaction, with apparent activation energy of 42.64 kJ/mol. However, the magnetization process of Fe₂O₃ is controlled by internal diffusion, with apparent activation energy of 21.30 kJ/mol. Compared to coal-based roasting process, Mn₂O₃ and Fe₂O₃ are easier to be reduced during the process of gas-based reduction roasting, and the manganese oxides can be directly reduced from Mn₂O₃ to MnO without the step of being reduced to intermediate product Mn₃O₄.

A process consisting of pre-discarding with heavy medium separation and ambient-temperature flotation was adopted for a scheelite ore sampled from the middle-layer mining zone of a tungsten mine in Hunan Province. A heavy medium separation test with the ore size of -15+0.5 mm as the feeding show that in the heavy medium with the density of 2.37 g/cm³, 31.37% of yielded tailings can be discarded, while the obtained heavy product has WO₃ grade and recovery increased to 0.34% and 96.62% respectively. A test by using a process of desulfurization flotation plus ambient temperature flotation for scheelite demonstrates that the process of pre-discarding with heavy medium has little effect on the operation loss rate of WO₃ in sulfur-containing products. However, the raw ore is directly taken into the flotation without a pre-discarding will lead to more tungsten minerals left in the middlings. The closed-circuit test shows that after a pre-discarding by heavy medium separation, the tungsten concentrate from ambient-temperature flotation has its WO₃ grade and recovery reaching 5.50% and 84.15% respectively. It is concluded that pre-discarding by using heavy medium cyclone is conducive to improvement of tungsten product index and comprehensive utilization of tailings.

After 6061-T4 aluminum alloy sheet for automobile was welded by laser welding, the microstructure, microhardness, strength and plasticity of welded joint, as well as fracture surface morphology of tensile specimen were studied by using metallographic microscope, transmission electron microscope, scanning electron microscope, Vickers hardness test and tensile test. The results show that the laser welded joint of 6061-T4 aluminum alloy has a coarse strip of grain structure in its base metal area, the weld seam has a structure of very fine as-cast dendrite in the center, acicular β″ precipitates segregate at grain boundary, and dislocation density decreases. It is found that both the strength (hardness) and plasticity of laser welded joint are lower than those of base metal.