An orthogonal experiment was performed for laser welding of 5 mm ZL114A and 6061 aluminum alloys, and the influences of welding parameters on the microstructure and mechanical properties of welded joint were investigated. It is shown that the influences of three parameters of laser welding power, defocus and welding speed are in a descending order. With laser welding power of 3 kW, welding speed of 16 mm/s and the defocus of -3 mm, the welded joint has an average tensile strength of 208.03 MPa and the elongation of 5.16%. Compared to ZL114A and 6061 aluminum alloy, the tensile strength is reduced to 64.14% and 65.60%, respectively, while the elongation is reduced to 41.38% and 33.70%, respectively. The welded joint presents a mixed mode of brittle and ductile fracture when failing under tensile.

An experiment on non-quenched and tempered steel F45MnVS was carried out by adopting controlled cooling after hot rolling. The mechanical properties, decarburized layer and microstructure of rolled steel without cooling and after controlled cooling process were compared for analysis. The results show that controlled cooling after hot rolling can lead to the steel with yield strength, elongation, section shrinkage and impact energy improved all, and with the decarburized layer being effectively controlled or even "disappeared". With the surface temperature of the hot-rolled steel decreased to 650 ℃, granular bainite begins to occur on the steel surface; with the surface temperature down to 460 ℃, much granular bainite occurs on the steel surface. It is shown that by using controlled cooling after hot rolling, the ferrite and pearlite on the steel surface and near 1/2 radius on the cross section of the steel become fine-grained. The total ferrite net is reduced, and long strip ferrite is transformed to blocky ferrite. Due to larger size, the central part of steel shows little difference in the microstructure.

Guizhou Jinfeng Gold Mine was taken as an engineering example for investigating effect of geometric features of rock surface on the performance of shotcrete support in the roadway constructed by drilling and blasting. The rock surface of the roadway was scanned by using a 3D laser scanner, and a 3D geometric model was established for the roadway. The actual shape of cross-sections was created by slicing the geometric model with a 3D software for analyzing the geometric features. With numerical models respectively established for the designed and actual sections, the variation in internal forces of the shotcrete and its supporting effect for the surrounding rock were analyzed. The results show that uneven rock surface of a roadway can lead to significant increase in the shear force and bending moment of shotcrete, but relatively small effect on the axial force. It is found that concave part of surrounding rock in a roadway is subjected to maximum negative bending moment, while convex part is mostly subjected to maximum positive bending moment. Under the interaction of axial force and bending moment, the shotcrete on convex part has an obvious lower safety factor, leading to weakened support to the surrounding rock, thus tensile failure is prone to occur.

The motion of spherical, tetrahedral and hexahedral particles flowing in a vertical pipe under different working conditions was simulated by using computational fluid dynamics-discrete element method (CFD-DEM), and the motion of irregular particles flowing in a vertical pipe was obtained. Based on comparison of local concentration and local flow rate, it is found that with lower flow rate at the inlet, the shape of particles can bring a larger influence to local concentration; while with a higher feed concentration and lower inlet flow rate, the shape of particles can bring obvious influence to local flow rate.

A complex precipitation method was adopted to synthesize CuO nanoparticles, and its morphology and structure were characterized. Then, the CuO nanoparticles were taken as the activator in the degradation of ofloxacin with persulfate. Based on the advanced technology of activated persulfate oxidation, the influences of different parameters, including concentration of K₂S₂O₈ and an initial pH of the ofloxacin solution, on the degradation activity of ofloxacin in the wastewater were investigated. It is found that the degradation rate can reach 95.6% with 10 mg/L of ofloxacin in the wastewater with an initial pH of 3.5, by adding 0.003 0 g/L CuO and 1.0 mmol/L K₂S₂O₈. The experiments on capturing free radicals show that SO₄^-· and O₂^-· are active species for the catalytic degradation of ofloxacin, which is possibly the catalytic reaction mechanism.

The amphibolite-type magnetite ore in Yuanjiacun Iron Mine was processed adopting a processing technique consisting of high pressure grinding roll (HPGR) plus pre-concentration, followed by staged grinding and staged separation process. In order to reduce the grinding feed in the following concentration, HPGR was introduced for superfine crushing, and the obtained material in a size fraction of－3 mm was treated by a wet pre-concentration process, yielding 22% coarse tailings for discarding. And then a pre-concentration process resulted in the obtained concentrate with TFe grade up to around 36%. The work index for grinding before and after adopting HPGR was reduced from 11.91 kW·h/t to 11.11 kW·h/t. An experiment was performed with a flowsheet of HPGR plus pre-concentration followed by staged grinding and staged separation process, yielding 33.92% concentrate grading 67.13% TFe at 75.75% recovery, showing the ratio of concentration down to 2.27 from 2.95. It is concluded that the above-mentioned processing technique can provide an energy-conservation and consumption-reduction solution for large-scale and low-cost exploitation of similar low-grade magnetite mines.

In the actual production, not only the copper oxide ore has a high content of slime, but also the copper minerals therein are prone to be lost during the beneficiation. In consideration of these problems, a cyclone desliming system was added to process the tailings after the copper sulfide was preferentially floated. The industrial experiment results show that a copper oxide concentrate grading 19.20% Cu can be obtained with the process recovery of 76.24% by adopting a direct sulphidizing flotation process to reclaim copper oxide minerals from copper sulfide flotation tailings, and the copper grade of tailings can be reduced to 0.94%. After copper sulfide flotation tailings were deslimed by cyclone, a process consisting of flotation of copper oxide minerals from underflow and a wet leaching to recover copper resource from fine slime (overflow) was adopted, resulting in a comprehensive copper oxide concentrate with Cu grade of 24.63% and process recovery of 85.55%, and the final tailings with Cu grade reduced to 0.60%. The indices of the copper oxide concentrate from the flowsheet containing cyclone desliming process are obviously superior to those by direct sulphidizing flotation process. Besides, this flow is relatively simple with reduced unit consumption of reagent for copper oxide flotation.

With nickel removal solution after copper electrolysis taken to be a substitute for sulfuric acid as the leaching agent, a processing technique consisting of oxygen pressure acid leaching, evaporative crystallization and reduction by SO₂ was adopted to realize utilization of arsenic matte resource. The results show that with sulfuric acid concentration at 120 g/L, leaching temperature of 120 ℃, oxygen partial pressure of 0.8 MPa, liquid-solid ratio of 7∶1 and leaching time of 2 h, the leaching rates of copper, arsenic and antimony from arsenic matte can reach 97.99%, 94.68% and 17.28%, respectively, showing an efficient leaching of copper and arsenic from matte copper and selective separation of antimony can be actualized. The solution obtained from pressure acid leaching was then subjected to vacuum evaporation followed by natural cooling for crystallization, leading to the precipitation of copper sulfate. And then reduction by SO₂ was adopted to prepare arsenic trioxid using mother liquor, leading to the obtained copper sulfate with purity up to 98.12% and the obtained arsenic trioxide with purity up to 99.49%.

Natural chalcopyrite (CuFeS₂) was used as a catalyst to activate persulfate (PS) for butyl xanthate wastewater treatment. The influences of CuFeS₂ dosage, PS dosage and initial pH of solution on the removal rate of butyl xanthate in CuFeS₂/PS system were investigated, and the recyclability of CuFeS₂ was also evaluated. The results show that CuFeS₂ can significantly activate PS. After 10 min reaction with initial pH of 3, CuFeS₂ dosage of 4 g/L and PS dosage of 5 mmol/L, the removal rate of butyl xanthate reached 99.23%, while the removal rate of total organic carbon (TOC) was only 31.29%. After the reaction time was extended to 60 min, the TOC removal rate reached 68.31%, and CuFeS₂ still sustained good catalytic activity after being recycled for five times. The UV-Visible absorption spectra of butyl xanthate wastewater degradation showed that butyl xanthate was initially oxidized to alcohols, then decomposed and mineralized to carbon dioxide and water. X-ray diffraction and fourier transform infra-red spectroscopy analysis showed that CuFeS₂ reacted with PS without surface passivation, thus could be reused. A free radical quenching test and an electron spin resonance analysis showed that the removal mechanism of xanthate included free radical degradation and CuFeS₂ physisorption, in which sulfate radical (SO₄^-·) and hydroxyl radical (HO·) were the main active substances to promote xanthate degradation, and the SO₄^-· played a dominant role.

In order to solve problems including serious atmospheric pollution by sulfur-containing flue gas and utilization of red mud, sulfur-containing flue gas was treated by using a wet process with red mud. Under the following optimal process conditions, including liquid-solid ratio of 9∶1, flue gas at a temperature of 60 ℃, liquid-gas ratio of 8.0 L/m³, liquid with pH of 5.6 for desulfurization, the SO₂ concentration in flue gas can be reduced from 5 000 mg/m³ to less than 35 mg/m³, meeting a standard of ultra-low emissions. In an industrial experiment on desulfurization with red mud for the flue gas from a 75 t/h coal-fired boiler, the SO₂ concentration in the low-sulfur flue gas was reduced from 4 100 mg/m³ to less than 30 mg/m³, with removal efficiency up to 99.68%；while the SO₂ concentration in the high-sulfur flue gas was reduced from 10 600 mg/m³ to less than 35 mg/m³, with a removal efficiency up to 99.89%. Based on the comparison between this wet desulfurization with red mud and with limestone-gypsum flue gas desulfurization process, it is found that the wet flue gas desulfurization process with red mud as desulfurizer can have the operation cost reduced by 20.05% for the treatment of same volume of flue gas with the same SO₂ concentration.