With cathode powder of spent lithium iron phosphate batteries as raw materials, selective lithium leaching was conducted in a tartaric acid - hydrogen peroxide system. The results indicate that stirring speed and liquid-solid ratio bring slight impact to the leaching rates of lithium and iron, while mass concentration of tartaric acid, leaching temperature and leaching time present remarkable influences. And hydrogen peroxide concentration mainly governs the iron leaching rate. Under the following optimal conditions, including mass concentration of tartaric acid of 150 g/L, stirring speed of 500 r/min, liquid-solid ratio of 6, leaching duration of 3 h, hydrogen peroxide concentration of 3 mol/L and leaching temperature of 70 ℃, the leaching rates of lithium and iron are 98.7% and 4.5% respectively. After the processes of evaporation, concentration and purification, the lithium leachate is subjected to carbonate lithium precipitation, yielding a lithium carbonate product with favorable crystallinity.

The copper extraction isotherm of 15% LIX984N-C organic phase system was plotted via the phase ratio variation method. The number of extraction stages was determined by the McCabe-Thiele graphical method, and the key factors affecting copper extraction were investigated. The results show that the maximum saturated copper loading capacity of 15% LIX984N-C organic phase is 10.65 g/L, which is basically consistent with the reference value of product specifications. With feed copper mass concentration of 8.4 g/L and phase ratio of 2∶1, a two-stage continuous extraction in the 15% LIX984N-C organic phase can meet the production requirements, with the copper concentration in raffinate controlled below 0.2 g/L and the copper extraction efficiency exceeding 97.86%. Under the following conditions, including both the extraction flow ratio and stripping flow ratio at 2∶1, stripping acidity of 180 g/L, feed copper mass concentration of 8 g/L and feed acidity of 7 g/L, the copper extraction efficiency reaches 98.51% and an average net organic loading is 2.72 g/L. It is verified that LIX984N-C extractant possesses excellent comprehensive extraction performance, which can provide technical references for the practical production with copper hydrometallurgical process.

A two-stage sulfuric acid leaching coupled with iron salt arsenic precipitation process was proposed to recovery valuable metals from copper smelting dust. The effects of initial mass concentration of sulfuric acid, liquid-solid ratio, reaction temperature and leaching system on the leaching rates of various metals in the first-stage leaching were systematically investigated; the effects of initial sulfuric acid concentration in the second-stage leaching on the total leaching rates of each metals were also studied under atmospheric pressure and oxygen pressure conditions, respectively. Meanwhile, the effects of different oxidants on the precipitation rates of arsenic and iron were explored for arsenic removal from leachate. It is found that the first-stage leaching at 70 ℃ for 2 h, with a single sulfuric acid system at an initial mass concentration of 50 g/L and a liquid-solid ratio of 4 mL/g, can bring the leaching rates of arsenic, copper, zinc and indium at 82.11%, 75.77%, 60.23% and 5.76%, respectively. And the second-stage leaching, performed at atmospheric pressure at 95 ℃ for 2 h with sulfuric acid at an initial mass concentration of 150 g/L and a liquid-solid ratio of 4 mL/g, results in the total leaching rates of zinc, copper, indium and arsenic up to 98.84%, 93.31%, 95.55% and 82.14%, respectively. With an oxygen flowrate of 250 mL/min, pH value of 1.5, Fe and As in a molar ratio of 1, the precipitation rates of arsenic and iron can reach 84.00% and 78.00%, respectively after 2 h reaction at 90 ℃. It is concluded that the proposed process can achieve efficient leaching of valuable metals and arsenic stabilization, providing technical support for clean treatment of flue dust.

An experimental study was conducted on preparation of metallized pellets by agglomeration and pre-reduction of titanium concentrate, for investigating the effects of carbon particle size, carbon dosage, roasting temperature and roasting time on the compressive strength and metallization rate of the pellets. The results show that the raw material is mainly composed of ilmenite with a small amount of magnetite, in which the size fraction of -69 μm accounts for approximately 91.39%, indicating that the material is fine-grained, and has favorable pelletizing performance. It is found that with carbon particle size of-1 mm (unclassified) and addition of carbon at 10%, both the green and fired pellets meet the process requirements in terms of compressive strength. On this basis, after roasting and reduction at 1 200 ℃ in a vacuum furnace for 30 min, qualified pellets with compressive strength of 1 224.60 N/P and a metallization rate of 50.48% can be obtained, which can meet the raw material requirements of electric furnace smelting and separation process. Within the experimental range, appropriately increasing the roasting temperature, prolonging the roasting time, and increasing the carbon addition are all beneficial to improving the metallization rate of pellets.

To explore the reduction process of antimony oxide (Sb₂O₃) in high-temperature molten lithium chloride, Sb₂O₃ was reduced to metallic antimony by electrolytic reduction and lithothermal reduction process respectively. The phase structure of products was analyzed by XRD, and electrochemical signals of Sb₂O₃ powder were accurately measured using molybdenum cavity electrode. Based on thermodynamic analysis and E-pO^2- diagrams, it is confirmed that Sb₂O₃ can be effectively reduced by electrolysis, yielding metallic Sb at potentials below 1.65 V (vs. Li/Li⁺). With a potential of 0.94 V (vs. Li/Li⁺) and electrolysis duration of 6 h, the antimony reduction rate can reach 82.0%. The conditions for lithium thermal reduction are as follows:metallic lithium is added at the theoretical dosage, reaction temperature of 923 K, and reaction time of 6 h. And the antimony reduction rate can reach 77.0% under these conditions.

An innovative technical route consisting of sintering and pyrometallurgical processing technique was proposed to extract iron from an iron concentrate of red mud. The results show that under the following optimal sintering conditions for high-alumina iron concentrate, including fuel ratio of 12%, moisture content of 18.5%-19.0%, and basicity (R₂) of approximately 4.85 (with quicklime as flux), the obtained sinter has its metallurgical properties meet the requirements of small-scale smelting equipment. To improve the fluidity of final high-alumina slag from blast furnace smelting, 17% calcium oxide is added for modification, leading to the viscosity of the slag down to 0.61 Pa·s at 1 450 ℃. As a result, an efficient slag-iron separation can be actualized. Such slag can be used to prepare premelted slag or synthetic slag. Compared with conventional technique for iron recovery from red mud, this process is characterized by a short flow, low cost and large processing capacity. This research provides a theoretical basis for resource utilization of red mud by using solid waste smelting furnaces and laboratory-scale blast furnaces.

A processing technique of gas-solid chlorination combined with water leaching was adopted for systematically investigating the phase evolution of spent lithium iron phosphate (LFP) cathode material during recycling, and the dynamic mechanism of lithium extraction via gas-solid chlorination of spent LFP cathode material was also clarified. It is found that the chlorination reaction of spent cathode material can proceed spontaneously in thermodynamics, and lithium can be converted into water-soluble phases through the gas-solid chlorination process. Under the optimized conditions of gas-solid chlorination, including reaction temperature of 150 ℃ and reaction time of 156 min, LiFePO₄ is almost completely transformed into FePO₄ and LiCl by water leaching, presenting a leaching rate of lithium at 99.09%, while the leaching rates of iron, phosphorus and aluminum just 0.089%, 0.078% and 0.339%, respectively. This process actualizes efficient and highly selective leaching of lithium. Meanwhile, the crystal structure and morphology of FePO₄ are well maintained during chlorination and water leaching, providing a stable precursor for the subsequent solid-phase synthesis and regeneration of lithium iron phosphate.

The effects of pre-oxidation and coating on the structure and sodium storage performance of resin-based hard carbon were investigated. The study reveals that the combined regulation of pre-oxidation and coating can effectively modify closed pores, graphite microcrystals and defect structures of hard carbon, thereby increasing available sodium ion storage and reversible deintercalation/intercalation sites. The as-synthesized hard carbon delivers a discharge capacity of 399 mAh/g at 0.1C rate, with an initial Coulombic efficiency of 87.3%, and retains 96.4% of this capacity after 50 cycles, which can satisfy the demand of sodium-ion batteries for hard carbon materials with high initial efficiency and long cycling life.

Conventional graphene reduction techniques feature high toxicity and energy consumption. To address those problems, a rapid reduction strategy for graphene oxide (GO) using pulsed discharge was proposed. A GO reduction is achieved at an instant high temperature induced by second-scale high-energy pulse at ambient temperature, yielding pulse reduced graphene oxide (PGO). It is confirmed that PGO has a high degree of reduction (C/O atomic ratio of 18.50), its specific surface area (506.46 m²/g) is 7.66 times that of GO; PGO has excellent hydrophobicity (water contact angle of 112.70°), and can efficiently separate diverse oils from water, which can be applied in continuous separation process.

Based on the existing removal routes of aluminum impurities during the recycling of spent lithium iron phosphate (LFP) batteries, the recycling process is divided into two major stages:removal of a large amount of aluminum via separation and sorting, and elimination of trace aluminum by hydrometallurgical process. This paper comprehensively reviews the advantages and disadvantages of various emerging technologies in terms of impurity removal efficiency, selectivity, residual aluminum content, economic performance and environmental impact. The future research trends are also prospected, for providing theoretical basis for the high-value utilization of spent LFP materials and green transformation of the industry.