Flotation tests were conducted for a low-grade copper-nickel sulfide ore with high content of mud and magnesium oxide from Xinjiang. Using sodium carboxymethyl cellulose and sodium silicate as a combined inhibitor, butyl xanthoxanthate and butyl ammonium black as a combined collector, a closed-circuit test with a flowsheet consisting of a Cu-Ni bulk flotation and a Cu/Ni separation produced a copper concentrate grading 25.11% Cu at 79.90% recovery, with MgO content of 2.02%, as well as a nickel concentrate grading 6.98% Ni at 75.01% recovery, with MgO content of 5.32%. It is concluded that effective recovery and separation of copper and nickel can be actualized.

In view of interference of the existence of selenium in determination of gold and silver in crude selenium sample, the sample with an addition of concentrated sulfuric acid was firstly heated to remove selenium. Then, sodium chloride solution was added to precipitate silver therein, and the obtained residue after filtration was taken for gold and silver determination using fire assay by gravimetry. Thus, a process of heating with sulfuric acid to remove selenium followed by fire assay gravimetry was established for continuous determination of gold and silver in crude selenium, and the effects of residual selenium, sulfuric acid dosage and heating time on the determination results were also discussed. Furthermore, such continuous determination process was also compared to the industrial standard method in terms of the analysis of gold and silver in crude selenium. By using the proposed continuous method, the relative standard deviations (RSD₇) of gold was within a range of 0.54%-1.30%, and the RSD₇ of silver was within a range of 0.28%-0.39%. The spike recovery of gold was 94.6%-101.3%, and the spike recovery of silver was 96.3%-100.1%. It is shown that the analysis results are consistent with those by industrial standard method. It is concluded that the proposed determination method, being fast and accurate, is suitable for determination of gold and silver in crude selenium.

In order to comprehensively utilize iron-containing dust and consume alkaline residue from petrochemical industry, a sintering pot test was conducted by adding iron-containing dust and the alkaline residue from petrochemical industry into raw materials for sintering. The results show that an addition of iron-containing dust and the alkaline residue from petrochemical industry can not only improve vertical sintering speed, utilization coefficient, yield rate and tumbler index, but also lead to increased content of alkali metals and Zn, as well as falling in the TFe content in the sintered ores. Thus, the sintered ore presents poor reduction performance, and poor low-temperature reduction pulverization indices. It is found that the raw material with the addition of iron-containing dust at an amount of 0.5% and the addition of alkaline residue from petrochemical industry at an amount of 0.05% can meet the requirement for feed to furnace, and also make it possible for the comprehensive utilization of iron-containing dust and consumption of alkaline residue from petrochemical industry.

Experiments on tempering at different cooling rates were conducted for annealed 30CrMnSiA steel to investigate the effect of cooling rate during tempering on the properties of tempered 30CrMnSiA steel and its microstructure evolution. The results show that the cooling rate during tempering has brought slight effect to the hardness, and a certain influence to impact properties of 30CrMnSiA steel. After tempering at 510 ℃, the 30CrMnSiA steel has its surface mainly subjected to compressive stress and the center subjected to tensile stress. A faster cooling rate during tempering will result in a higher residual stress on the surface of the sample. During the tempering process, C element mainly combines with Fe element to form Fe-C compounds, while a trace of C element, together with Cr and Si elements, forms Cr-C compounds and Si-C compounds. It is found that the rapid cooling rate has slight effect on the content and size of carbides.

A typical metal mine with a smelter in Hunan Province was taken as an example, and 22 key factors affecting the environmental risk diffusion path of heavy metal pollution area were chosen based on data crawling and on-site case investigation, as well as systematical sorting. Nemerow integrated pollution index (NIPI) of soil was calculated using Nemerow pollution index method, and then was used to aid the identification of key factors. Results show that atmospheric deposition and soil permeability are selected as the environmental risk diffusion path for heavy metal pollution of soil based on the analytic hierarchy process, and the key factors for environmental risk diffusion include distance from pollution source, PM₁₀ content in air, hard cover on ground surface, anti-seepage measures, soil pH value and soil organic matter (SOM) content. It is found that the NIPI of the soil is positively correlated to soil pH value, SOM, PM₁₀, but negatively correlated to the distance from pollution source, hard cover on soil surface and anti-seepage measures. The correlation coefficient fits well with the factor weight (R²=0.63).

V₂O₅ thin films were prepared on FTO conductive glass substrates by electrodeposition-assisted sol-gel technique, and effects of precursor concentration on the structure, morphology and optical properties of V₂O₅ thin films were investigated. The results of XRD and XPS show that the prepared films are all V₂O₅ films, and the diffraction peaks in the XRD pattern are sharp, indicating that the films have good crystallinity. No other impurity peaks appeared in the XRD and XPS spectra, which indicated that the prepared V₂O₅ film had high purity. The results of SEM show that the surface of V₂O₅ film is uniform and compact, and mainly consists of spaced small particles. UV/VIS/NIR test results indicate that the transmittance of V₂O₅ thin film is greatly affected by the concentration of precursor, and reaches the highest of 80.18% when the concentration of precursor is 1∶100. The infrared spectrum test result shows that the infrared transmittance of V₂O₅ thin film decreases from 89.5% to 20.5%, as its semiconductor state at low temperature changes to metal state at high temperature.

To investigate the current situation of heavy metal pollution in a stone coal mine in Hunan Province, the content of Cd, Hg, As, Pb, Cr, Cr (Ⅵ), Zn, Fe, and Mn in water and soil samples was determined by using ICP, and the risk of heavy metal pollution was evaluated by using the Nemerow pollution index and potential ecological hazard index respectively. The results show that concentrations of Cd, Cr (Ⅵ), Zn, Fe and Mn in water are 1.935 5, 0.025 3, 6.024 9, 16.222 0 and 4.214 9 mg/L on average, with pollution indices of 387.10, 5.06, 3.01, 54.07 and 42.15, presenting the pollution degree in the following descending order: Cd>Fe>Mn>Cr (Ⅵ)>Zn; while content of Pb、Zn、Cr、As、Hg and Cd in the soil is 8.51, 38.59, 18.65, 10.01, 0.18 and 3.41 mg/kg on average, with ecological risk coefficient of 2.13, 0.98, 0.85, 18.00, 28.55 and 339.80 on average, presenting pollution degree in the following descending order: Cd>Hg>As>Pb>Zn>Cr. It is shown that the comprehensive potential ecological risk indices of the whole mine is 390.31, indicating a higher ecological pollution risk. The mine area is polluted by several kinds of heavy metals, especially in the downstream areas of waste dump and sedimentation tank.

The furnace slag generated from smelting of South African vanadium-titanium magnetite was taken in an experimental study by adopting direct reduction followed by melting, and then analyzed by XRD to investigate the effect of basicity on the metallurgical properties of the slag, as well as on the separation of iron from slag. Furthermore, the effect of basicity on the melting characteristics and viscosity of the slag were also explored. Results show that melting at 1 450 ℃ with the addition of carbon at an amount of 5%, the slag has its corresponding softening temperature, hemisphere temperature and flow temperature rising gradually with the increase in basicity. With the basicity ranging from 0.9 to 1.2, the melting temperature of slag increases rapidly, and the measured and calculated viscosity of slag presents a trend of an initial decrease followed by increase. When the basicity rising from 0.9 to 1.4, the diffraction peaks of pyroxene and feldspar in the slag climb to the high value and then start to fall, and the relative contents of perovskite and calcium-aluminum spinel gradually increase after an initial decrease. It is shown that the slag with basicity of 1.2 and viscosity of 0.130 Pa·s can present better performance.

Experimental studies were carried out for iron recovery from the leaching residue of lateritic nickel ore containing 51.38% TFe and 2.01% S, by adopting processing techniques of centrifugal separation, magnetic separation and magnetic roasting. It is found that the process of magnetic roasting followed by magnetic separation is an efficient technique to recover iron from such leaching slag. It is shown that the process of coal-based reduction followed by low-intensity magnetic separation (LIMS) can produce the concentrate grading 62.77% TFe at 94.04% recovery, and the process of gas-based reduction followed by LIMS leads to the concentrate grading 68.77% TFe at 95.15% recovery, with sulfur content of 0.12% in the impurity, which can meet the quality standard for iron concentrate. Although the process of direct reduction followed by LIMS can produce the concentrate grading 90.89% TFe at 88.90% recovery, it is shown that there is higher content of sulfur in the concentrate.

316L stainless steel coatings were prepared on the surface of 304 stainless steel by using laser cladding at different scanning speed, and then metallographic microscopy, X-ray diffractometer, scanning electron microscopy and microhardness tester were adopted respectively to investigate the macroscopic morphology, phase composition, microscopic structure and microhardness for the coatings. The results showed that the 316L coating had a single-phase austenitic structure, and as the scanning speed increased, the grain size of the coating became smaller due to the reduction in the laser power density and heat input, and an increase in the cooling speed. It is found that the microhardness of the coatings is positively correlated with scanning speed, and the 316L coatings prepared by laser cladding at a scanning speed of 1 400 mm/min presents the highest microhardness of about 275HV_0.3. The improvement of the microhardness of the coating is ascribed to the effect of solid solution strengthening caused by lattice distortion combined with the effect of fine crystal strengthening. The wear test showed that the average friction coefficient of 316L coatings was significantly lower than that of 304 stainless steel substrate. And the 316L coating prepared by laser cladding at 1 400 mm/min has a friction coefficient of 0.424 and wear rate of 2.29 × 10^-6 mm³/(N·m), and is prone to abrasive wear.