MINERALS ENGINEERING
·
2018
·
IF 2.707
Dandan Gong,Kanggen Zhou,Changhong Peng,Junjie Li,Wei Chen
Extraction of tungsten from scheelite is important for the processing of tungsten resources for tungsten metallurgical companies. However, there are many difficulties to leach scheelite compared to wolframite. Compared with calcium tungstate (CaWO 4 ), magnesium tungstate (MgWO 4 ) is a readily soluble substance in NaOH solution. In this paper, conversion of CaWO 4 to MgWO 4 through roasting a mixture of scheelite and MgCl 2 was investigated systematically. The leaching performance of the roasted products in NaOH solution was also studied. Thermodynamic analyses and experimental results showed that MgWO 4 could be prepared through reaction of CaWO 4 with MgCl 2 . Increasing roasting temperature and MgCl 2 dosage could increase the extent of conversion of CaWO 4 to MgWO 4 . Additionally, leaching experiments showed a good leachability of the roasted products with a tungsten leaching efficiency of 98.79% in 4 M NaOH solution at 90 °C. This work may provide an alternative approach for the extraction of tungsten from scheelite.
研究领域:
冶金工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2022
·Vol. 53
·期 4
·2634-2646
·
IF 2.872
Huang Jingdong,Sohn Il,Kang Youngjo,Yang Xiao
Earth’s commercial and affordable zinc reserves are expected to be depleted in less than 50 years. Since electric arc furnace (EAF) dust contains a certain amount of Zn, recovery of Zn from EAF dust has become an important issue to assure a sustainable resource supply in the future. The key technical challenge is that Zn mainly occurs in EAF dust as ZnFe 2 O 4 , a very stable crystal which is difficult to reduce or leach. MgCl 2 is believed to be effective in breaking the structure of ZnFe 2 O 4 . This work investigates the fundamentals of the reaction between MgCl 2 and ZnFe 2 O 4 . Experiments show that Zn in ZnFe 2 O 4 is chlorinated to ZnCl 2 quickly with priority over Fe, implying the efficacy of MgCl 2 in separating Zn and Fe in ZnFe 2 O 4 by selective chlorination. Effects of MgCl 2 /ZnFe 2 O 4 molar ratio and temperature on the reaction are clarified. Overuse of MgCl 2 slows down the reaction and is detrimental to the selective chlorination of Zn. Temperature can effectively increase the reaction rate as well as the priority of chlorinating Zn. Utilization of MgCl 2 could be high, because evaporation of MgCl 2 is not as fast as the reaction with ZnFe 2 O 4 . According to these results, a new technology to recover Zn from EAF dust by using MgCl 2 is proposed.
研究领域:
冶金工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
RESOURCES CONSERVATION AND RECYCLING
·
2024
·
IF 11.2
Jingdong Huang,Xiao Yang
Natural Zn reserves may be exhausted in the coming decades. Electric arc furnace (EAF) dust is an essential secondary Zn resource. However, the traditional methods for separating Zn from EAF dust are plagued by high energy consumption, large carbon emissions, and severe environmental pollution, which hinder sustainable development. To address these challenges, a novel technology using molten MgCl 2 has been proposed. Under an air atmosphere at 1000°C, the chlorination percentage of Zn can exceed 97%. The ZnCl 2 content in the volatile products can reach up to 85 mass%, with minor impurities consisting mainly of PbCl 2 , KCl, and NaCl. Molten salt electrolysis experiments indicate that removing Pb 2+ and Fe 3+ ions and subsequently preparing metallic Zn is feasible. With its streamlined process, characterized by high efficiency and low energy consumption, this technology offers a clean and sustainable solution for metal recovery from EAF dust.
研究领域:
冶金工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOM
·
2019
·Vol. 71
·期 8
·2827-2833
·
IF 2.305
Gong Dandan,Zhou Kanggen,Li Junjie,Peng Changhong,Chen Wei
Conversion of CaWO 4 to MgWO 4 by roasting scheelite with MgCl 2 is the key step for the subsequent alkaline extraction of tungsten from scheelite. In this study, the factors influencing the conversion efficiency of MgWO 4 during the roasting of synthetic scheelite and MgCl 2 were evaluated, and the reaction kinetics were explored by model fitting. The results indicate that the conversion efficiency increases with an increase in roasting temperature and magnesium chloride dosage, and that a decrease in mineral particle size also increases the conversion efficiency. Moreover, the roasting reaction between synthetic scheelite and MgCl 2 at 773–923 K fits well to the Avrami–Erofeev kinetic model, and the roasting reaction is controlled by both diffusion and chemical reaction. This study contributes to a better understanding of the roasting process of scheelite with MgCl 2 and the development of a new route for extracting tungsten from scheelite.
研究领域:
冶金化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Sustainable Metallurgy
·
2023
·Vol. 9
·期 3
·1253-1266
·
IF 2.4
Huang Jingdong,Li Guangqiang,Yang Xiao
Natural Zn reserves might be exhausted in the following decades. Electric arc furnace (EAF) dust is an essential secondary Zn resource. The recovery of Zn from EAF dust is a critical factor in the sustainable development of the Zn industry and steelmaking industry. Efficient destruction of the ZnFe 2 O 4 crystal structure and separation of Zn and Fe are the key issues to recycle EAF dust. Molten metal chlorides are believed to be effective in breaking the structure of ZnFe 2 O 4 . This work clarifies the distinct reaction behavior between ZnFe 2 O 4 and MgCl 2 or CaCl 2 . Experiments show that although MgCl 2 is a more powerful chlorinating agent, the capability of separating Zn and Fe is not as good as that of CaCl 2 . Fast and selective chlorination of Zn from ZnFe 2 O 4 happens by reacting ZnFe 2 O 4 and MgCl 2 –CaCl 2 mixture. CaCl 2 facilitates the formation of stable Fe-bearing phases, such as MgFe 2 O 4 and Ca 2 Fe 2 O 5 , thereby inhibiting the chlorination of Fe. Moreover, it becomes more effective in promoting the selectivity of chlorinating Zn by increasing temperature after adding CaCl 2 in MgCl 2 . When ZnFe 2 O 4 is subjected to chlorination using a MgCl 2 –CaCl 2 mixture (MgCl 2 –CaCl 2 –ZnFe 2 O 4 molar ratio = 1.5:1.5:1) at 950 °C for 120 min, the process results in a chlorination percentage of over 90% for Zn, with Fe chlorination percentage lower than 5%. These results demonstrate the prospect of efficient separation of Zn from ZnFe 2 O 4 by reaction with molten MgCl 2 –CaCl 2 mixture. Graphical Abstract
研究领域:
冶金工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Ying Li,Peng Liu,Cong Ma,Na Zhang,Xiaoqin Shang,Liming Wang,Fengwei Xie
As high-amylose starch (HAS) has a higher content of linearly structured chains than other types of starch, it is more scientifically interesting to realize enhanced properties or new functions for food and materials applications. However, the full dissolution of the compact granule structure of HAS is challenging under moderate conditions, which limits its applications. Here, we have revealed that the granule structure of HAS can be easily destructed by certain concentrations of acidic ZnCl2, neutral MgCl2, and alkaline CaCl2 solutions (43, 34, and 31 wt %, respectively) at a moderate temperature (under 50 °C). The ZnCl2 and CaCl2 solutions resulted in complete dissolution of HAS granules, whereas small amounts of HAS granule remnants still existed in the MgCl2 solution. The regenerated starch from the CaCl2 solution was completely amorphous, that from the ZnCl2 solution only presented a weak peak at 17°, and that from the MgCl2 solution contained V-type crystallites. No new reflections were found on the FTIR spectra indicating that all these three chloride solutions can be considered as a nonderivatizing solvent for starch. In all the three cases, nanoparticles were formed in the regenerated starch, which could be due to the aggregation of starch chains or their complexation with the metal cation. In addition, their water absorption ratio was 1.5 to 3 times that of the control (treated in water).
研究领域:
食品科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2025
·
IF 3.5
Kexin Li,Huifang Zhang,Mingzhe Dong,Zhongmei Song,Mingzhen Li,Chunyan Wang,Haining Liu,Xiushen Ye,Guosheng Shi,Zhijian Wu
Anhydrous magnesium chloride is a conventional raw material for the electrolytic production of magnesium metal. Its preparation contributes about 50 % of the overall cost of the electrolytic production of magnesium metal. The search for a new process for the preparation of anhydrous magnesium chloride at a low cost has attracted much attention. In this study, the effects of graphene on the pyrolysis of MgCl 2 ⋅6H 2 O were investigated by comparing the thermal decomposition processes of MgCl 2 ·6H 2 O and MgCl 2 ·6H 2 O-graphene, using TG, DTG, DSC, XRD, FTIR techniques and theoretical calculations. It was found that the addition of graphene can reduce the energy barrier for the pyrolysis of MgCl 2 ⋅6H 2 O, accelerate the pyrolysis reactions, reduce the reaction temperature and energy consumption. The cation-π interactions between graphene and Mg 2+ , and the good thermal conductivity of graphene accelerate the thermal decomposition. The results obtained would be helpful for understanding the decomposition processes and mechanisms of MgCl 2 ·6H 2 O under the assistance of graphene, and for exploring new techniques for MgCl 2 ·6H 2 O dehydration.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Kexin Li,Mingzhe Dong,Li Han,Mingzhen Li,Huifang Zhang,Xiushen Ye,Haining Liu,Siyuan Zhang,Quan Li,Honghui Liu,Guosheng Shi,Zhijian Wu
The electrolytic production of magnesium metal requires anhydrous MgCl 2 with a high-purity, which is usually prepared through the dehydration of MgCl 2 ·6H 2 O at a relatively high temperature. The Mg 2+ cations in MgCl 2 ·6H 2 O have a high affinity for water and the complete dehydration of MgCl 2 ·6H 2 O is difficult due to the hydrolysis of the hydrated Mg 2+ cations. The hydrolysis usually results in the formation of unwanted oxycompounds of magnesium. In this study, the effects of the addition of AlCl 3 and NH 4 Cl on the dehydration of MgCl 2 ·6H 2 O were investigated by comparing the thermal decomposition processes of MgCl 2 ·6H 2 O, MgCl 2 ·6H 2 O/AlCl 3 , and MgCl 2 ·6H 2 O/NH 4 Cl, using Raman, FT-IR, TG-DSC, XRD techniques and theoretical calculations. It was found that the addition of AlCl 3 or NH 4 Cl significantly reduces the dehydration energy barrier of MgCl 2 ⋅6H 2 O, decreases the dehydration temperature, and suppresses the hydrolysis of MgCl 2 ·6H 2 O. Anhydrous AlCl 3 can extract water from MgCl 2 ·6H 2 O at room temperature. The interactions between Al 3+ or NH 4 + and H 2 O, together with the substitution of Cl - for H 2 O, result in the easier production of anhydrous MgCl 2 . During the dehydration of MgCl 2 ·6H 2 O, several impurities including MgO are generated, indicating that the environment remains to be an important controlling factor for the dehydration of MgCl 2 ⋅6H 2 O. The results obtained would be helpful for understanding the dehydration processes and mechanisms of MgCl 2 ·6H 2 O under the assistance of AlCl 3 and NH 4 Cl, and for exploring new techniques for MgCl 2 ·6H 2 O dehydration.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2015
·
IF 3.942
Cen Tang,Yanxia Jin,Jiqing Lu,Xiaonian Li,Guanqun Xie,Mengfei Luo
A series of Mg catalysts supported on SiO 2 were prepared by an incipient wetness impregnation method and tested for gas phase dehydrochlorination of 1,1,2-trichloroethane. It was found that these catalysts were very active and selective for the reaction. The catalytic performance depended on the Mg loading rather than the Mg precursors as the catalysts using Mg(NO 3 ) 2 ·6H 2 O and MgCl 2 ·6H 2 O as the precursors showed the similar performance. A catalyst containing 10 wt.% of Mg showed the best performance with a steady state TCE conversion of 92% and cis -dichloroethene selectivity of 91%. Moreover, characterizations of the catalysts revealed the formation of Cl-containing Mg species on the surface during the reaction. The analyses of the compositions of the stable catalysts under working conditions indicated a Cl/Mg ratio of 1, suggesting that Mg(OH)Cl could be the active sites for the reaction.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
Journal of Magnesium and Alloys
·
2022
·
IF 11.813
Yongyang Zhu,Mili Liu,liming Zeng,Yin Wang,Daifeng Wu,Rui Li,Qing Zhou,Renheng Tang,Fangming Xiao
The hydrolysis of MgH 2 delivers high hydrogen capacity (15.2 wt%), which is very attractive for real-time hydrogen supply. However, the formation of a surface passivation Mg(OH) 2 layer and the large excess of H 2 O required to ensure complete hydrolysis are two key challenges for the MgH 2 hydrolysis systems. Now, a low-cost method is reported to synthesize MgH 2 @Mg(BH 4 ) 2 composite via ball-milling MgH 2 with cheap and widely available B 2 O 3 (or B(OH) 3 ). By adding small amounts of B 2 O 3 , the in-situ formed Mg(BH 4 ) 2 could significantly promote the hydrolysis of MgH 2 . In particular, the MgH 2 –10 wt% B 2 O 3 composite releases 1330.7 mL·g −1 H 2 (close to 80% theoretical hydrogen generation H 2 ) in H 2 O and 1520.4 mL·g −1 H 2 (about 95%) in 0.5 M MgCl 2 in 60 min at 26 °C with hydrolysis rate of 736.9 mL·g −1 ·min −1 and 960.9 mL·g −1 ·min −1 H 2 during the first minute of the hydrolysis, respectively. In addition, the MgCl 2 solution allows repeated use by filtering and exhibits high cycle stability (20 cycles), therefore leading to much reduced capacity loss caused by the excess H 2 O. We show that by introducing B 2 O 3 and recycling the 0.5 M MgCl 2 solution, the system hydrogen capacity can approach 5.9 wt%, providing a promising hydrogen generation scheme to supply hydrogen to the fuel cells.
研究领域:
材料科学
·
能源化学
·
无机合成
·
氢能技术
·
表面工程
✓ 已验证
DOI
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Qiang Wang,Haiqing Hao,Zhengyang Wu,Meng Wang,Zongyu Feng,Yongqi Zhang,Xiangxin Xue,Xiaowei Huang
The MgCl 2 wastewater generated from rare earth extraction and separation process was treated by spray pyrolysis with H 2 O 2 as an additive for the first time, and achieving full recycling of MgCl 2 wastewater. The effect of H 2 O 2 on the spray pyrolysis process, the kinetic of the spray pyrolysis process, and the mechanism of the effect on the activity of MgO powder were investigated. The results showed that H 2 O 2 and the O 2 produced by its decomposition had strong oxidizing property, which contributed to the removal of Cl roots. The kinetic results indicated that the rate determining step of MgCl 2 spray pyrolysis was transformed from chemical reaction to diffusion process after the temperature exceeded 1023 K. The activity study indicated that the doping of Cl led to severe distortion of the MgO grains, and polycrystalline basic magnesium chloride had more defect sites too. Thus, the powder showed high activity. Moreover, the thermal decomposition rate of MgCl 2 reached 99.83 %, the alkalinity of the powder reached 0.044 mol/g, and the iodine absorption value reached 131.81 mg I 2 /g MgO at temperature of 1073 K and amount of H 2 O 2 addition of 1 %. Meanwhile, the high purity hydrochloric acid with concentration of 6.54 mol/L was obtained.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY
·
2020
·
IF 4.608
Yongyichuan Zhang,Xuelai Zhang
PV-PCM technology can not only achieve higher photoelectric conversion efficiency, but also has the advantages of energy saving, high efficiency, and economical applicability. In this paper, a new type of CaCl 2 ·6H 2 O-MgCl 2 ·6H 2 O composite PCM for PV-PCM was prepared by physical blending method using calcium chloride hexahydrate-magnesium chloride eutectic mixture as PCM and expanded graphite as carrier. The shape stability, thermal properties and thermal reliability of CaCl 2 ·6H 2 O-MgCl 2 ·6H 2 O eutectic materials under EG conditions were discussed. The change of temperature and output power of PV panel combined with PV-PCM was studied. The experimental results show that the CaCl 2 ·6H 2 O-MgCl 2 ·6H 2 O composite with 8 %EG has high phase change enthalpy (171.4 kJ/kg), suitable phase change temperature (27.1 °C), and negligible supercooling degree (0.11 °C) and excellent thermal conductivity (3.359 W/m·K). After 100 heating–cooling cycles, the modified composite phase change material still has excellent thermal reliability. Surface temperature of photovoltaic panels can be significantly reduced, and the average temperature of photovoltaic panels can be kept below 40 °C. The photovoltaic panel power can work for a long time (3.5–4 h) close to the rated power, keeping the photovoltaic panel power at a high and stable state, and producing 7.9% more power than using only photovoltaic panels to generate electricity.
研究领域:
能源材料
·
光伏技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）