The basic flow of Midrex and HYL/Energiron technologies for direct reduction in a shaft furnace and the direct reduced iron output by each processing technique in recent years are firstly introduced, and then the equipment, raw materials and process characteristics of those two technologies are analyzed based on comparison. Based on the expounding of technical R&D and investment of global steel companies in these two technologies, it is pointed out that the development of hydrogen-based direct reduction process in a shaft furnace is closely related to grade of pellet ore, heat adsorption during hydrogen-based reduction reaction process, technologies for large-scale green hydrogen production and production cost among others. It is important for sustainable development of Chinese iron and steel industry to adopt hydrogen-based direct reduction in a shaft furnace that conforms to the national conditions.

With manganese sulfate as raw material and hexadecyl trimethyl ammonium bromide as modifier, trimanganese tetroxide was synthesized by complex-precipitation method, with which lithium manganate cathode material was then synthesized by high-temperature solid-state reaction. The effects of modifier amount on the morphology and particle size of trimanganese tetroxide and the specific discharge capacity of lithium manganate cathode material were all discussed. Results show that serious particle agglomeration can occur in the trimanganese tetroxide synthesized without modifier. With 3.0 g/L hexadecyl trimethyl ammonium bromide as the modifier, the synthesized trimanganese tetroxide has uniform particle size, and is dispersed without any agglomeration. Spinel lithium manganate was synthesized with the self-made modified trimanganese tetroxide, and then compared with the spinel lithium manganate synthesized with three kinds of trimanganese tetroxide available on the market. The results show that the lithium manganate synthesized with the self-made modified trimanganese tetroxide can present better electrochemical performance, delivering an initial discharge capacity of 120.43 mAh/g, with a retention rate of 96.79% after 50 cycles at 1C.

Ball milling was adopted to assist leaching of valuable metals from the cathode powder of spent batteries in citric acid and hydrogen peroxide system. It is found that ball milling can exert mechanical energy on the reaction solution, leading to changes in its structure and physical and chemical properties. As a result, chemical reactions can occur, which not only increases reaction rate, but also shortens leaching time. It is shown that after 30 min leaching at 60 ℃, with citric acid concentration of 0.8 mol/L, H₂O₂ at a mass fraction of 20%, liquid-solid ratio of 6∶1, and rotation speed of 60 r/min for a ball mill, the leaching rates of lithium, nickel, cobalt and manganese can reach 99.6%, 99.5%, 99.3% and 98.5% respectively. It is concluded that this processing technique, being characterized by low cost and high efficiency, can provide a certain reference for recycling of spent batteries.

A single-factor experiment was conducted to explore the influence of rotation speed and lateral swing speed of polishing brush, and polishing current on the performance of copper foil and pinholes. Based on that, the polishing process was also optimized by applying response surface methodology, and thus the performance and apparent quality of copper foil was also improved. The results show that by using on-line polishing, with the rotation speed of the polishing brush at 450 r/min, the lateral swing speed of 350 r/min, and the polishing current of 0.50 A, the smooth surface (S surface) of the generated copper foil is uniform, and the pinhole defects are significantly reduced.

A mineral processing test was conducted to treat a low-grade rubidium-bearing lepidolite ore from Hunan Province with the grade of Li₂O and Rb₂O respectively at 0.27% and 0.17%. A flowsheet including a desulphurization and a lithium flotation was adopted, and an efficient collector CK was used in combination with dodecylamine to collect lithium minerals under weak alkaline conditions. In a closed-circuit test, a lithium concentrate was produced with Li₂O grade and recovery of 2.71% and 86.34%, Rb₂O grade and recovery of 1.02% and 51.24%, respectively. It is concluded that efficient utilization of low-grade lepidolite ore can be actualized.

Cathode and anode materials in spent lithium iron phosphate battery powder are difficult to be separated by flotation. In order to solve this problem, it was proposed that lithium iron phosphate battery powder was pretreated by oxidative roasting, and then subjected to a flotation process for seperation between the cathode and anode materials of lithium iron phosphate. The results show that after lithium iron phosphate battery powder is pretreated by oxidative roasting at 500 ℃ for 30 minutes, the subsequent flotation process can lead to the graphite-based anode material with carbon grade up from 47.63% to 97.70%, and the cathode material with carbon grade down from 24.00% to 1.01%, presenting a significant separation effect. In comparison, the battery powder without pretreatment has cobweb-like long carbon-chain organic matter on its surface, which causes adhesion between cathode and anode materials of batteries, resulting in poor separation effect by flotation. The pretreatment of oxidative roasting can effectively eliminate the long carbon-chain organic matter on those cathode and anode materials, thus enhancing the difference in surface properties between cathode and anode materials. As a result, the enhanced flotation separation effect makes graphite-based anode material recycled from spent lithium iron phosphate batteries.

With tetraethyl orthosilicate as silicon source and cetyltrimethylammonium bromide (CTAB) as a surfactant and pore-forming agent, a carbon-coated mesoporous hollow silicon oxide as anode material was synthesized by adopting the modified stöber method and carbonthermal reduction. The results show that different volume ratio of ethanol to water can bring important impact to the particle size, morphology and performance of SiO_x nanospheres. With ethanol and water in a low volume ratio, the obtained nanomaterial has a low sphericity and becomes oval; as the ratio increases, the nanomaterial becomes larger in size; with ethanol and water in a ratio of 0.45, the obtained SiO_x nanospheres are around 300 mm in size. The button batteries assembled with such nanospheres deliver a reversible specific capacity of 813 mAh/g after 200 cycles at a current density of 100 mA/g, and 704 mAh/g after 1 200 cycles at 500 mA/g, retaining 82% of this capacity, with a capacity attenuation rate of 0.015% after each cycle.

In order to identify the feasibility of preparing alkaline pellets with low-quality magnesium-containing flux, experiments on pelletizing, preheating and roasting were carried out. Three kinds of magnesium-containing flux from Wulongquan Mine of WISCO Resources Group Co., Ltd., including interbedded dolomite, light-burnt material and lightburnt dolomite, were taken for pelletizing, and then effects of different magnesia flux and the adding amount on pelleting, as well as following preheating and roasting processes of alkaline pellet were all explored. The results show that the green ball prepared with the flux of interbedded dolomite presents superior performance. It is found that with alkalinity of 0.8, the green ball prepared with two different blending schemes have drop number of 4.1 and 6.6 respectively from height of 0.5 m, and compressive strength of 20.3 N/pellet and 22.3 N/pellet respectively. By increasing the addition of magnesia flux in two blending schemes, both preheated balls and roasted balls have their strength decreased after an initial improvement. With alkalinity between 0.6 and 0.8, the prepared pellet can have compressive strength of 2 620 N/pellet and 2 963 N/pellet respectively after preheating and roasting process. It is recommended that with interbedded dolomite and light-burnt material as magnesia flux, the alkaline magnesium-containing pellet prepared with alkalinity of 0.6-0.8 can meet industrial requirements.

A review of comprehensive recycling technologies for graphite anodes in spent lithium-ion batteries is presented, including hydrometallurgical process, a combination of pyrometallurgical and hydrometallurgical process, as well as mechanical recycling. And then, an in-depth analysis of advantages and disadvantages of each technology is also presented. It is particularly pointed out that there are various recycling technologies, but the development of an efficient and environmentally-friendly closed-circuit recycling process still faces challenges. The recycling approaches of graphite anodes in spent lithium-ion batteries are discussed in details, such as usage as anodes of rechargeable batteries, or for preparation of graphene. The research direction in the future is also forecasted aiming to provide theoretical and technical support for reutilization of graphite anodes in spent lithium-ion batteries with high-value added. It is suggested that research should focus on developing a simple, efficient and clean closed-circuit recycling processes to improve the recovery rate and purity of graphite anode materials while reducing environmental pollution. The research hotspots in the future should include lattice reconstruction and repairing technologies for graphite anode materials, as well as exploration of new applications of graphite anode materials in the fields of energy storage materials, catalysts, adsorbents among others.

Based on comparison of cadmium immobilization with 4 types of minerals originated from 14 places in Hunan Province, four kinds of natural and efficient remediation materials (including limestone from Yujiaao of Ningxiang County, low-grade manganese ore from Nanmuchong of Xiangtan County, bentonite from Mazongling of Taoyuan County, and sepiolite from Xingang of Shimen County) were selected. The kinetic rate of cadmium immobilization by these four natural minerals is in the following descending order: bentonite > limestone > sepiolite > manganese ore. The cadmium adsorption by four kinds of minerals increases as the initial cadmium mass concentration increases. With cadmium mass concentration no higher than 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite; with cadmium mass concentration exceeding 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: bentonite > limestone > manganese ore > sepiolite. The adsorption behavior follows Langmuir adsorption model, and the maximum adsorption capacities of bentonite, limestone, manganese ore and sepiolite are 29.38 mg/g, 14.51 mg/g, 9.67 mg/g and 5.27 mg/g respectively. With pH of solution within the range of 6 to 9, the removal efficiency of cadmium by four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite. It is concluded that the cadmium immobilization with natural minerals is related to chemical composition of minerals, initial cadmium mass concentration, and pH value.