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As the economy recovered from the COVID-19 epidemic, the price of Li 2 CO 3 skyrocketed to the highest. Recovery of lithium from spent lithium-ion batteries (LIBs) is significant for addressing lithium shortage and environmental issues. Sulfation roasting is often accused of being unsustainable and not environmentally friendly due to the consumption of expensive sulfation reagents and emission of SO 2. Herein, a novel and green recycling process for selective separation of lithium from spent LiMn 2 O 4 (LMO) batteries was proposed based on a SO 2 emission free sulfation roasting with waste copperas. Lithium in the cathode power were selectively sulfated into soluble Li 2 SO 4 with a conversion of 99.50%, while manganese was riched as insoluble oxides. At low temperature (e.g. 400 °C), LMO were difficult to be sulfated due to the limited sulfation ability of SO 4 2- and mass transfer. When the roasting temperature reached 700 °C, SO 2 was produced and the generated SO 2 reacted in situ with the LMO to form Li 2 SO 4 and MnSO 4 , preventing SO 2 emissions into the atmosphere. As temperature continued to increase, the MnSO 4 acted as a sulfation reagent and sulfated the unreacted LMO. All the sulfur was immigrated in Li 2 SO 4 , rather than being emitted as SO 2. [Display omitted] [ABSTRACT FROM AUTHOR]

A low-cost and eco-friendly recycling method is crucial for recovering valuable elements from end-of-life lithium-ion batteries (LIBs), which plays a vital role in addressing resource scarcity and reducing the environmental impact. This study aims to develop a low-temperature pyro-metallurgical combined process to recycle spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523). Unlike traditional pyrometallurgy methods that generate liquid alloys and slags at temperatures exceeding 1000 °C, the (NH 4) 2 S 2 O 8 roasting approach operates at 350 °C and converts NCM523 to water-soluble sulfates, exhibiting remarkable leaching efficiencies of Li, Ni, Co, and Mn, with values of 99.43 %, 99.87 %, 98.88 %, and 99.19 %, respectively. Systematic studies were conducted to investigate the influence of roasting temperature, (NH 4) 2 S 2 O 8 -to-NCM mass ratio, and roasting time on the sulfation process. Furthermore, the mechanism of sulfation reaction was identified by combining experiments with thermodynamic calculation. At temperatures above 160 °C, (NH 4) 2 S 2 O 8 decomposes into (NH 4) 2 S 2 O 7 , which reacts with NCM. Lithium in a layered structure forms Li 2 SO 4 , while transition elements form MnSO 4 , Li 2 Co (SO 4) 2 , and NiSO 4. At around 350 °C, (NH 4) 2 S 2 O 8 further decomposes into NH 4 HSO 4 , releasing SO 2 and NH 3. SO 2 reacts with remaining NCM or unsulfated transition metal oxides, converting them into MnSO 4 , Li 2 Co (SO 4) 2 , and NiSO 4. Above 800 °C, the metal sulfates decompose into stable oxides. This study presents a low-temperature sulfation method that effectively disintegrates the crystal structure of lithium metal oxides without the need for acids or reducing agents. [Display omitted] • A low-temperature and acid-free leaching process for spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 was proposed. • The sulfation mechanism of LiNi 0.5 Co 0.2 Mn 0.3 O 2 was revealed. • More than 98 % of the Li, Ni, Co, and Mn were leached from spent LiNi 0.5 Co 0.2 Mn 0.3 O 2. [ABSTRACT FROM AUTHOR]

The recovery of valuable metals from spent lithium-ion batteries (LIBs) is of utmost significance for environmental protection and alleviating resource shortages. Traditional sulfation roasting techniques were accused of their unsustainability and negative environmental impact, such as the consumption of expensive sulfation reagents and the emission of SO 2. This study compared the performance of cobalt-lithium co-sulfation and selective sulfation processes under high and low sulfur input conditions with waste ferrous sulfate as sulfation reagent. The results revealed that selective roasting can efficiently achieve lithium separation without SO 2 emission. Additionally, a sulfation roasting mechanism for SO 2 emission-free conditions under low sulfur input was proposed. At 650 °C, spent lithium cobaltate (LCO) was sulfated via ion exchange with FeSO 4 and gas-solid reactions with SO 2 , and the lithium in the outer layer was selectively sulfated. Partially sulfated CoSO 4 was then served as a sulfation agent to sulfate the unreacted LCO at 800 °C, allowing the sulfur element to be fully recovered and recycled in the form of Li 2 SO 4. By comparing the co-sulfation and selective sulfation processes, an efficient and eco-friendly method for recovering metals from spent lithium-ion batteries was established. [Display omitted] • This study employed the concept of "waste + waste → resources". • Waste copperas as the only additive is used for sulfation roasting of LiCoO 2. • A sulfation roasting mechanism for SO 2 emission-free under low sulfur input was proposed. • Cobalt-lithium co-sulfation and selective sulfation processes were compared. [ABSTRACT FROM AUTHOR]

With the rapid development of new energy devices, a large amount of spent lithium-ion batteries (LIBs) are produced every year. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. In this study, a novel approach by in situ thermal reduction technology with waste copperas is developed to recycle valuable metals from spent LiCoO 2 (LCO) batteries. The mechanism study through in situ x-ray diffractometer and thermal analysis reveal that the sulfation of LCO underwent two pathways i.e., ion exchange and gas-solid reactions. In the ion exchange pathway, the layered structure of LCO collapse due to the reduction by divalent iron in copperas, and the detachment of lithium ions result in a larger lattice spacing of transition metal layer and formation of a stable spinel structure. Furthermore, the SO 2 generated from the decomposition of iron sulfates reduces the unreacted LCO through gas-solid interactions, realizing the sulfation of lithium and cobalt completely. Economic analysis indicates the potential benefit of this process is approximately 8266$/t spent LCO. This study provides an alternative technological route and a new approach to green recovery of the spent LCO batteries, exhibiting great potential for wide applications. [Display omitted] • This study employed the concept of "waste to wealth". • The conversion efficiency of Li and Co reached 100% after sulfation reaction. • An environmentally friendly approach for recycling spent LiCoO 2 battery is proposed. • The mechanism of the sulfation reaction of LiCoO 2 was obtained. [ABSTRACT FROM AUTHOR]

Spent lithium-ion batteries (LIBs) are essential secondary resource, containing valuable metal elements including lithium, cobalt, nickel, manganese. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. Herein, a sustainable and facile process for Li 2 CO 3 and Mn 2 O 3 recovery from spent LiMn 2 O 4 batteries (LMO) was proposed via sulfation roasting with waste copperas. The leaching efficiencies of Li and Mn reached approximately 100 % and 82 % under the optimal conditions, and the final recovered products were Li 2 CO 3 and Mn 2 O 3 with high purities. The sulfation reaction between LMO and copperas was the transition from solid-solid to gas-solid reaction. During the sulfation reaction, LMO spinel structure was decomposed into MnO 2 and Mn 2 O 3 crystal structures, and the anti-fluorite structure Li 2 O embedded in the spinel structure was released. The Li 2 O was easily to be sulfated, while MnO 2 was partly reduced by Fe2+ to more stable spinel structure Mn 2 O 3. Furthermore, FeSO 4 decomposed into SO 2 gas, which greatly improved the sulfation reaction through permeating into the unreacted core of LMO. As a result, the spinel structure of Mn 2 O 3 was broken, and Mn was escaped to combine with SO 4 2- to form MnSO 4. This research provided an alternative technological route for green recovery of spent LMO batteries, demonstrating high potential for broad application. [Display omitted] • An environmentally friendly approach for recycling LiMn 2 O 4 battery was proposed. • This study employed the concept of "waste + waste → resources". • Waste copperas as the only additive is used for sulfation reaction of LiMn 2 O 4. • The mechanism of the sulfation reaction of LiMn 2 O 4 was investigated. [ABSTRACT FROM AUTHOR]

CO 2 mineral sequestration is a promising method for abating global warming. Mineral carbonation with titanium-bearing blast furnace slag (TBFS) can offer a sustainable option for simultaneous CO 2 emission reduction and comprehensive utilization of solid waste. In this study, a novel process combining CO 2 mineral sequestration and rutile beneficiation was proposed by using TBFS and copperas as feedstocks. TBFS and copperas were roasted at 550–750 °C to convert the calcium and magnesium into the corresponding sulfates, while titanium in the TBFS was beneficiated to rutile. The roasted slag was then subjected to carbonation followed by recovery of rutile and hematite through flotation and magnetic separation, respectively. The effects of process parameters were studied systematically. It was found that addition of Na 2 SO 4 significantly enhanced the conversion efficiency of Ti (from 53% to 98%). The mechanism revealed that the addition of Na 2 SO 4 promoted the formation of molten Na 3 Fe(SO 4) 3 , and gas-liquid-solid reactions proceeded much faster and efficiently. The carbonation of sulfated TBFS results indicated that the optimal CO 2 storage capacity can reach 187 kg t−1 TBFS. In this process, two solid wastes were utilized for CO 2 mineralization, realizing the multiple benefits of CO 2 emission reduction, solid waste disposal as well as valuable byproducts recovery. [Display omitted] • A novel process for co-disposal of Ti-bearing blast furnace slag and copperas was proposed. • Rutile beneficiation and CO 2 mineralization were realized simultaneously in the route. • The addition of Na 2 SO 4 significantly enhanced the conversion efficiency of Ti. • The maximum CO 2 storage capacity reached 187 kg t−1 TBFS. [ABSTRACT FROM AUTHOR]

Manganese-containing soil (M-S) is a solid waste generated from the mining and extraction of manganese ore. In this study, the low-temperature denitration performance of Mn-S was investigated via XRF, XRD, XPS, H 2 -TPR, NH 3 -TPD and DRIFTS, aiming at exploring its utilization approach as low-temperature NH 3 -SCR catalyst. The results showed that Mn-S exhibited a relatively high catalytic activity reaching over 75% NO conversion from 150 °C to 200 °C. The physical and chemical properties of Mn-S were studied, indicating that the manganese content of Mn-S reached 8.2% with mainly surface Mn atomic valence state of Mn3+. In situ DRIFTS results revealed the SCR reaction mechanism of Mn-S, suggesting that Mn-S obeyed the E-R reaction mechanism. The Ce/Mn-S catalyst was synthesized by impregnation method. The denitration activity improved and reached 92.4% at 200 °C. A series of characterizations were studied to investigate the strengthening mechanism after doping Ce. It's found that introducing of Ce could increase the content of Mn4+ and chemisorbed oxygen, NH 3 adsorption capacity and reducibility. It was found from in situ DRIFTS experiments that doping of Ce changed the reaction mechanism due to the conversion of inactive substance, which was mainly affected by E-R and L-H. [Display omitted] • The excellent low-temperature denitration performance of Mn-S was investigated. • Ce-dropped Ce/Mn-S catalyst exhibited high denitration performance and improved N 2 selectivity. • Doping Ce enhanced the content of Mn4+ and chemisorbed oxygen. • Supporting Ce changed the SCR reaction mechanism due to the conversion of inactive substance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A green process for recovering valuable metal from spent LIBs was proposed. • Waste copperas was used as reductant and sulfating agent. • The redox interaction mechanism was presented. • A preliminary economic evaluation of the whole process was carried out. A large amount of hazardous spent lithium-ion batteries (LIBs) is produced every year. Recovery of valuable metals from spent LIBs is significant to achieve environmental protection and alleviate resource shortages. In this study, a green and facile process for recovery of valuable metals from spent LIBs by waste copperas was proposed. The effects of heat treatment parameters on recovery efficiency of valuable metals and the redox mechanism were studied systematically through phase transformation behavior and valence transition. At low temperature (≤460 °C), copperas reacted with lithium on the outer layer of LIBs preferentially, but the reduction of transition metals was limited. As the temperature rose to 460–700 °C, the extraction efficiency of valuable metals was greatly enhanced due to the generation of SO 2 , and the gas–solid reaction proceeded much fast than the solid–solid reaction. In the final stage (≥700 °C), the main reactions were the thermal decomposition of soluble sulfates and the combination of decomposed oxides with Fe 2 O 3 to form insoluble spinel. Under the optimum roasting conditions, i.e., at a copperas/LIBs mass ratio of 4.5, and a roasting temperature of 650 °C and roasting time of 120 min, the leaching efficiencies of Li, Ni, Co and Mn were 99.94%, 99.2%, 99.5% and 99.65%, respectively. The results showed that valuable metals can be selectively and efficiently extracted from the complex cathode materials by water leaching. This study used waste copperas as an aid to recover metals and provided an alternative technical route for green recycling of spent LIBs. [ABSTRACT FROM AUTHOR]

Pyrolusite tailings (PTs) is a solid waste discharged from the mining of high grade pyrolusite, and is also regraded as an important secondary resource of manganese. However, its extraction requires an expensive reductant used for the reduction of Mn(IV) to low valence. In this paper, an innovative process using in situ redox interaction of PTs with waste copperas (as reductant and sulfating agent) followed by water leaching for efficient manganese extraction was proposed. The in situ redox interaction mechanism was investigated systematically. At lower temperatures (＜500 °C), Fe(II) was the main reductant by direct solid-to-solid reaction. In the temperature range of 500–650 °C, the Mn(IV) in PTs was reduced to Mn(II) due to the synergistic effect of Fe(II) and SO 2 , and then Mn(II) was sulfated into water-soluble MnSO 4. The reduction of Fe(III) into Fe(II) by SO 2 occurred i.e. the Fe(II)⇌Fe(III) redox cycle. And the generated FeSO 4 continued to react with PTs, indicating that the Fe(II)⇌Fe(III) redox cycle facilitated the extraction of manganese. Furthermore, high roasting temperatures caused MnSO 4 to decompose into insoluble Mn 2 O 3 , inhibiting the extraction. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel indirect carbonation process by using solid waste as reagent was proposed. • Nickel was co-extracted in this process, enhancing the economy. • Process intensification mechanism by Na 2 SO 4 was presented. • The maximum CO 2 storage capacity reached 291 kg·t−1 laterite ore. CO 2 mineral sequestration is one of the most promising strategies for combating global warming, which is composed of direct and indirect pathways. However, the high cost and heat consumption for recycling reagents used in the indirect carbonation process is the biggest obstacle for its widespread applications. In this study, a novel process by using a solid waste, copperas, as reagent to extract magnesium and nickel from laterite ore was proposed for simultaneous CO 2 mineralization and recovery of nickel. In this process, the copperas was decomposed into SO 2 , which sulfated the laterite ore by in situ gas–solid reaction. The addition of Na 2 SO 4 facilitated the formation of low melting point substances, converting the gas–solid reactions into a multiphase gas–liquid-solid reaction, thus the extraction was enhanced. Meanwhile, the heat of sulfation of laterite ore can compensate the heat of copperas decomposition, reducing the overall energy consumption. The maximum extraction efficiency of 94 % for Mg and 87 % for Ni was achieved at Na 2 SO 4 dosage larger than 10 wt%. The carbonation of MgSO 4 -riched leachate experiments revealed the optimal CO 2 storage capacity was approximately 291 kg·t−1 laterite ore. Compared with the conventional acid-based Mg extracted process for CO 2 mineralization, the cheap copperas avoided the recycle of reagent and obtained weak acidic leachate, reducing the amount of alkali used in the subsequent carbonation process. [ABSTRACT FROM AUTHOR]

Lepidolite is an important mineral resource containing lithium, rubidium, cesium and potassium. Most researches focused on the extraction of lithium from lepidolite, while the co-extraction of rubidium, cesium and potassium was ignored. In this study, the extraction of lepidolite at lower temperature was investigated by using iron(II) sulfates feedstock, aiming at enhancing the extraction of lepidolite, especially for rubidium and cesium. Thermodynamic predictions indicated that the co-extraction of lithium, rubidium, cesium and potassium from lepidolite by roasting with iron(II) sulfate was feasible, but high temperature worked against the extraction. The effects of process parameters on the extraction were investigated systematically. It was found that the optimal roasting conditions were as follows: 50% lepidolite particles <74 μm, temperature of 675 °C, iron(II) sulfate to lepidolite mass ratio of 2:1, and holding time of 90 min. The extraction efficiencies of Li, Rb, Cs and K were 92.7%, 87.1%, 82.6% and 86.2%, respectively. The reaction between lepidolite concentrate and iron(II) sulfate followed two pathways, i.e. gas-solid and liquid-solid reaction. The formation of pyrosulfates with low smelting point promoted the reaction by reacting with lepidolite through a circular transformation between sulfates and pyrosulfates. Compared with the conventional extraction of lepidolite, the proposed process operates at a lower temperature and co-extracts various metals, exhibiting great potential in industrial application. [Display omitted] • Co-extraction of alkali metals from lepidolite at low temperature was achieved. • The formation of pyrosulfates promoted the reaction. • The extraction followed by two pathways, i.e. gas-solid and liquid-solid reaction. [ABSTRACT FROM AUTHOR]