In an experiment, with hydrochloric acid as leaching agent and NaClO₃ as oxidizing agent, lithium was selectively leached from cathode material of spent lithium iron phosphate battery, and the effects of factors, including dosage of hydrochloric acid, solid-liquid ratio and reaction time, on the lithium leaching rate were investigated. It is shown that with an addition of hydrochloric acid at an amount of 1.0 time theoretical value, solid-liquid ratio of 1∶3 and reaction time of 3 h, the average lithium leaching rate can reach 99.33% by using this process. After that, magnesium hydroxide and sodium hydroxide were added into the raffinate in turn to remove impurities of P, Al and Fe. And then, the obtained solution was used to prepare Li₂CO₃ at 95 ℃ by adding anhydrous sodium carbonate. After water washing to remove NaCl, a high purity Li₂CO₃ (99.62%) can be obtained, which meets the industrial standard for industrial-grade lithium carbonate.

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.

Limonite-type and serpentine-type nickel laterite ores were taken for experiment. A coupled process for extracting nickel and cobalt was adopted, consisting of chloridizing leaching with HCl as the initial leaching medium for limonite-type nickel laterite ore, and selective hydrolysis for serpentine-type nickel laterite ore. The leaching rates of Ni, Co, and Fe from limonite-type laterite ore were 99.6%, 100%, and 96.9% respectively, under the conditions including acid-to-ore ratio of 5∶4, liquid-to-solid ratio of 4∶1, reaction temperature of 100 ℃, and reaction time of 30 min. After that, the obtained lixivium of limonite-type nickel laterite ore, being mixed with concentrated HCl in a volume ratio of 1∶4, was used to leach serpentine-type nickel laterite at 150 ℃ for 90 min with a liquid-to-solid ratio of 1∶1, resulting in the leaching rates of Ni and Co up to 84.9% and 100%.

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.

Experiments of roasting and leaching of some sulfur concentrate were performed, and the effects of two schemes with fixed bed roasting and fluidized bed roasting on gold extraction were analyzed. The results showed that with the sulfur concentrate at a sizing of 80% -0.074 mm, the proper conditions for a fixed bed roasting included a roasting temperature of 650 ℃ and roasting time of 4 h; while the proper conditions for a fluidized bed roasting included a roasting temperature of 650 ℃ and roasting time of 3 h, roasting gas and material in a ratio of 2.1 m³/kg. The calcines obtained by these two roasting methods were then separately leached for 24 h with the slurry concentration of 33% and pH of 11.5, 2 h alkali treatment and CG505 dosage of 10 kg/t, resulting in the leaching rate of gold reaching 69.45% and 69.92% respectively. It is shown that the fluidized bed roasting can bring in a better gold extraction result. This research results can provide a technical basis for recovery of valuable elements from sulfur concentrate.

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%.

As for a cobalt-containing raffinate in Africa, several neutralizing agents, including limestone, lime, limestone-lime, as well as a combination of flotation tailings and lime, were separately used for impurity removal in the study, and a preliminary economic evaluation was also conducted. It is found that a combination of flotation tailings and lime is a good choice for impurity removal by neutralization, which can not only save the usage of limestone, but also recover part of the copper and cobalt in flotation tailings. Using this process, the leaching rates of copper and cobalt from flotation tailings can reach 81.69% and 41.10%, respectively. After an addition of lime, the precipitation rates of copper and cobalt can reach 95.43% and 13.64% respectively, and the iron removal rate is up to 99.86%.

The spent cathode carbon block after aluminum electrolysis was treated by acid leaching with a mixed solution of sulfuric acid and ammonium sulfate, and the effects of factors, such as molar ratio of sulfuric acid to ammonium sulfate, liquid-solid ratio, leaching temperature and time, on the leaching rate of cryolite from this spent cathode carbon sulfate were investigated. The results show that at a leaching temperature of 70 ℃, with liquid-solid ratio of 8 mL/g, sulfuric acid and ammonium sulfate in a molar ratio of 4, a 120-min leaching process can lead to the leaching rate of cryolite up to 99.48%. The leaching residue, being composed of carbon and calcium fluoride and free of leaching toxicity, can be treated as a general solid waste.

The effects of different cooling rates in retrogression and re-aging on the microstructure and properties of Al-Zn-Mg-Cu alloy profiles were investigated by performing tests on hardness, electrical conductivity, room temperature tensile, local corrosion and stress corrosion, combined with microstructure characterization by using metallographic microscopy and transmission electron microscopy. The results show that retrogression with cooling rates of 660.0, 12.7 and 0.5 ℃/min, the alloy has a tensile strength of 663.1, 653.4 and 636.9 MPa, an electrical conductivity of 35.1% IACS、35.2% IACS and 36.8% IACS, an exfoliation corrosion in the form of EC, EB-and EB, and a stress corrosion sensitivity of 4.7%, 4.0% and 3.2%, respectively. The precipitates at grain boundaries along the direction of length, with an average size of 48.7, 54.7 and 68.7 nm, are distributed with a spacing of 28.9, 33.6 and 40.3 nm, respectively. The variation in size and distribution is the main reason for variation of the above-mentioned properties. With both mechanical properties and corrosion resistance taken into consideration, it is appropriate to select cooling rates ranging from 0.5 ℃/min to 12.7 ℃/min for retrogression.

The problems of oxidation and corrosion of LIBs copper foil in its production and application have restricted its service life and battery safety. Based on the research status of anti-oxidation technologies for LIBs copper foil in recent years, the mechanism of different passivation methods is summarized. After an introduction of the corrosion mechanism of copper foil fluid in Li-ion battery electrolyte, the research progress in improving corrosion resistance by modification of copper foil surface is reviewed. On this basis, the prospects of chromium-free passivation technology and surface modification technologies for copper foil are presented. At last, a clean, eco-friendly and efficient anti-oxidation and anti-corrosion concept is proposed.