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.

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.

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.

Hollow microsphere BiOBr photocatalyst was synthesized using hydrothermal method. BiOBr photocatalyst doped with different content of Fe were prepared by regulating Fe³⁺/Bi³⁺molar ratio. The crystal structure, morphology, optical and electrochemical properties of Fe-doped BiOBr photocatalyst were characterized respectively. With organic dye Congo red (CR) as the pollutant, its photocatalysis was evaluated by testing the degradation effect of the photocatalyst on the pollutant under visible light irradiation. The results showed that the photocatalytic material with 7% Fe doping exhibited the optimal photocatalytic performance. The degradation efficiency of CR within 180 min of irradiation with 5 W light-emitting diode (LED) was 89.66%, which was much higher than that of undoped BiOBr (62.82%). It is found that the enhanced photocatalytic performance of Fe-doped BiOBr is attributed to the enhanced light absorption and the efficient transfer and separation of photogenerated carriers.

In order to effectively separate acid, arsenic and copper/zinc from smelting waste acid, a kind of simulated waste acid was taken to be treated by using electrodialysis with bipolar membrane. The effects of running time, acidity, initial concentration of arsenic and copper/zinc on the separation rate of acid, copper/zinc, and arsenic were investigated, and the process was also applied in the treatment of waste acid from copper smelting for verification. Besides, the surfaces of anion exchange membrane, cation exchange membrane and bipolar membrane in electrodialysis after long-term usage were analyzed and characterized. The results show that with the running time more than 80 min, arsenic concentration less than 9 g/L, acidity less than 5% and copper/zinc concentration less than 5 g/L, three kinds of solution respectively containing arsenic, valence metallic salt and acid were obtained. It is shown that the arsenic separation rate is more than 93%, the recovery rate of copper/zinc is more than 96%, and the recovery rate of acid is more than 97%. More than 90% of other metallic ions (such as Na, K, Mg, Ca) in waste acid are trapped in the bipolar membrane salt chamber, thus making inorganic salt ions effectively recovered from waste acid by an open circuit. After nearly two years of application, electrodialysis membrane and bipolar membrane are observed to have no obvious change in the apparent morphology, and no obvious precipitant attached on them.

The effects of different heat treatment processes on the microstructure and mechanical properties of RM80 steel were studied by means of scanning electron microscopy, Rockwell hardness tester and universal testing machine. As quenching temperature increases, carbides in RM80 steel gradually dissolve and the original austenite grains continue to grow. During tempering process, the structure of RM80 steel changes from tempered troostite to tempered sorbite, and martensite can still be observed in the structure of RM80 that is tempered after quenching at a higher temperature. After quenching at 1 150 ℃ and then three times of tempering at 550 ℃, RM80 steel finally has a good match between strength and plasticity, with a yield strength of 1 244 MPa, a tensile strength of 1 590 MPa, and an elongation of 12.0%.

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 process consisting of direct reduction roasting and magnetic separation was adopted to separate and recover iron and titanium from ilmenite rough concentrate. A single factor experiment was conducted to explore effects of several factors, including reduction temperature, reduction time, coal powder dosage, borax dosage, bentonite dosage, grinding fineness, and magnetic field intensity, on the grades and recovery of iron concentrate and titanium concentrate. Then, the optimal processing parameters were finally determined. A reduction roasting runs at 1 200 ℃ for 2 h by adding coal powder at an amount of 40%, borax at 2% and bentonite at 2%, with a grinding fineness of 84% -38 μm, followed by a magnetic separation with field intensity of 79.62 kA/m, resulting in an iron concentrate grading 82.57% Fe at 83.59% recovery, and a titanium concentrate approaching 49.23% Ti grade at 85.18% recovery. It is shown that good beneficiation and smelting indicators are obtained.

Based on the calculation theory of solid-liquid two-phase flow and consideration of collision effect, a hydrodynamic model was established by using VOF model, and reamer operation under different working conditions was also analyzed by numerical simulation. It is shown that a reamer working with an inclination angle of 45° can have a good effect, resulting in percentage of disturbed area at 68.32%. As the rotating speed of reamer increases, disturbance of the waters above a reamer gradually becomes violent, and the scope of waters being disturbed also gradually becomes wider first and then narrows down. It is concluded that a reamer should work with an inclination angle of 45°, rotate at a speed of 45 r/min and move laterally at a speed of 0.2 m/s, which can reduce disturbance to the waters brought by its operation, thus minimize the secondary pollution to the waters to a certain extent.

With Ca (NO₃)₂·4H₂O and Al (NO₃)₃·9H₂O as raw materials and urea as precipitant, a precursor Ca-Al-LDHs was prepared by microwave heating and hydrothermal synthesis. A product of Ca-Al hydrotalcite (Ca-Al-LDOs) was obtained after roasting, and it was used to adsorb fluorine in wastewater. It is found that Ca-Al-LDOs are of typical layered structure similar to hydrotalcite. With pH of 2, initial concentration of F^- ion at 500 mg/g, adsorbent dosage of 2.5 g/L and reaction time of 180 min, the adsorption capacity reaches 173.9 mg/g and the removal rate of fluorine reaches 92.01%. It is found that the process of adsorption conforms to the Freundlich adsorption isotherm mode, and its kinetics conforms to the quasi-second-order kinetic model. The adsorbent Ca-Al-LDOs can be reused after desorption, with defluorination rate keeping at 68.92% after 8 cycles of regeneration.