Extraction of Lithium，Rubidium，Cesium from Zinnwaldite by Low Temperature Alkaline Roasting-Water Leaching AITranslate
Abstract AITranslate
At present，the resources that could be used for industrial lithium extraction mainly include salt lake brine and lithium ore，among which lithium containing ores include spodumene and lepidolite，etc. However，zinnwaldite，which was also pegmatite lithium ore，has not received sufficient attention due to its high iron and fluoride contents. Therefore，zinnwaldite was not used for industrial lithium extraction，the current laboratory treatment of zinnwaldite methods were direct carbonation，hydrochloric acid leaching，oxalic acid leaching，calcium carbonate digestion，however，these methods still existed some disadvantages such as high energy consumption，long reaction time and corrosive gas. In this experiment，a promising process of treating zinnwaldite by molten alkali roasting at low temperature was studied，molten sodium hydroxide could effectively decompose silicate minerals，while avoiding the formation of HF，the addition of CaO could adjust the iron lithium mica from acidic rocks to basic rock，so lithium could be more easily dissociated from the mineral，while avoiding fluoride and silicon ions into the liquid phase. The effects of different roasting conditions on the leaching rate of lithium，the reaction mechanism and the migration behavior of major elements in the roasting process were discussed. It was known from the chemical element analysis that the contents of lithium，iron and fluorine of zinnwaldite were 1.34%，2.83% and 5.38% respectively. The effects of roasting temperature，time and additive on the leaching efficiency were evaluated. X-ray diffraction (XRD) was employed to characterize the sinters. The results showed that when the additive amount of NaOH was low，partial zinnwaldite did not decompose，with the increase of the additive amount of NaOH，the overall extraction rates of lithium and cesium showed a rising trend，and the sinters were mainly NaAlO2 and Fe2O3；The extraction rates of lithium and cesium could be improved by adding proper amount of CaO. Different roasting temperature would lead to the change of reaction pathway，when roasting temperature was low，the main roasting products of zinnwaldite were Na4SiO4，ferrite and Ca（OH）2，and with the increase of temperature，the main roasting products of zinnwaldite changed into NaAlO2 and Fe3O4，the extraction rate of lithium had also increased. The results showed that leaching rates of Li，Rb，Cs，Al and Si were 86.8%，98.7%，31.0%，20.0% and 3.3% respectively under the optimum conditions including NaOH∶CaO∶Ore mass ratio of 2∶0.5∶1，roasting temperature of 650 ℃，roasting time of 1.5 h，liquid-solid ratio （L/S） = 2，leaching time of 60 min，and leaching temperature of 90 ℃. It could be inferred that after roasting，The alkali metals reacted with Al to form aluminates，Ca reacted with Si to form calcium silicate，in addition，Fe existed as oxide. The XRD analysis indicated that the main phases of the residues were NaAlO2，Na4SiO4，CaSiO3. Combined with XRD patterns of roasted products and thermal analysis of materials，it could be seen that the whole roasting process was in an endothermic state. When the temperature was lower than 200 ℃，the main reason for the endothermic phenomenon was dehydration of materials，accompanied by 6.30% weight loss. When the temperature was about 300 ℃，sodium hydroxide melting，dehydration，mineral decomposition and ferrous ion oxidation were the main causes of the endothermic reaction，accompanied by 8.22% weight loss. When the temperature reached 500 ℃，the main causes of the endothermic reaction were dehydration and mineral decomposition. Based on the above analyses，it was confirmed that chemical reactions occurred in the roasting process of zinnwaldite. Scanning electron microscopy (SEM) pictures of cross-section of the sinters showed that the sintering mixure experienced densification at 650 ℃，the distribution areas of Na，K and Al were consistent，and the distribution areas of Ca and Si were highly correlated，Fe had no correlation with other elements. The experimental analysis of leaching conditions showed that low liquid-solid ratio，long leaching time and high leaching temperature could effectively reduce Al leaching.
KeyWords AITranslate
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Basic Information:
DOI：10.13373/j.cnki.cjrm.XY21120025
Chinese Library Classification Number:TF826.3
Citation Information:
At present，the resources that could be used for industrial lithium extraction mainly include salt lake brine and lithium ore，among which lithium containing ores include spodumene and lepidolite，etc. However，zinnwaldite，which was also pegmatite lithium ore，has not received sufficient attention due to its high iron and fluoride contents. Therefore，zinnwaldite was not used for industrial lithium extraction，the current laboratory treatment of zinnwaldite methods were direct carbonation，hydrochloric acid leaching，oxalic acid leaching，calcium carbonate digestion，however，these methods still existed some disadvantages such as high energy consumption，long reaction time and corrosive gas. In this experiment，a promising process of treating zinnwaldite by molten alkali roasting at low temperature was studied，molten sodium hydroxide could effectively decompose silicate minerals，while avoiding the formation of HF，the addition of CaO could adjust the iron lithium mica from acidic rocks to basic rock，so lithium could be more easily dissociated from the mineral，while avoiding fluoride and silicon ions into the liquid phase. The effects of different roasting conditions on the leaching rate of lithium，the reaction mechanism and the migration behavior of major elements in the roasting process were discussed. It was known from the chemical element analysis that the contents of lithium，iron and fluorine of zinnwaldite were 1.34%，2.83% and 5.38% respectively. The effects of roasting temperature，time and additive on the leaching efficiency were evaluated. X-ray diffraction (XRD) was employed to characterize the sinters. The results showed that when the additive amount of NaOH was low，partial zinnwaldite did not decompose，with the increase of the additive amount of NaOH，the overall extraction rates of lithium and cesium showed a rising trend，and the sinters were mainly NaAlO2 and Fe2O3；The extraction rates of lithium and cesium could be improved by adding proper amount of CaO. Different roasting temperature would lead to the change of reaction pathway，when roasting temperature was low，the main roasting products of zinnwaldite were Na4SiO4，ferrite and Ca（OH）2，and with the increase of temperature，the main roasting products of zinnwaldite changed into NaAlO2 and Fe3O4，the extraction rate of lithium had also increased. The results showed that leaching rates of Li，Rb，Cs，Al and Si were 86.8%，98.7%，31.0%，20.0% and 3.3% respectively under the optimum conditions including NaOH∶CaO∶Ore mass ratio of 2∶0.5∶1，roasting temperature of 650 ℃，roasting time of 1.5 h，liquid-solid ratio （L/S） = 2，leaching time of 60 min，and leaching temperature of 90 ℃. It could be inferred that after roasting，The alkali metals reacted with Al to form aluminates，Ca reacted with Si to form calcium silicate，in addition，Fe existed as oxide. The XRD analysis indicated that the main phases of the residues were NaAlO2，Na4SiO4，CaSiO3. Combined with XRD patterns of roasted products and thermal analysis of materials，it could be seen that the whole roasting process was in an endothermic state. When the temperature was lower than 200 ℃，the main reason for the endothermic phenomenon was dehydration of materials，accompanied by 6.30% weight loss. When the temperature was about 300 ℃，sodium hydroxide melting，dehydration，mineral decomposition and ferrous ion oxidation were the main causes of the endothermic reaction，accompanied by 8.22% weight loss. When the temperature reached 500 ℃，the main causes of the endothermic reaction were dehydration and mineral decomposition. Based on the above analyses，it was confirmed that chemical reactions occurred in the roasting process of zinnwaldite. Scanning electron microscopy (SEM) pictures of cross-section of the sinters showed that the sintering mixure experienced densification at 650 ℃，the distribution areas of Na，K and Al were consistent，and the distribution areas of Ca and Si were highly correlated，Fe had no correlation with other elements. The experimental analysis of leaching conditions showed that low liquid-solid ratio，long leaching time and high leaching temperature could effectively reduce Al leaching.
quote
| GB/T 7714-2015 | [1] Ruoyu Wang, Zhenping Cai, Xijun Tian, et al. Extraction of Lithium，Rubidium，Cesium from Zinnwaldite by Low Temperature Alkaline Roasting-Water Leaching[J]. Chinese Journal of Rare Metals, 2024, 48(12): 1743-1754. DOI:10.13373/j.cnki.cjrm.XY21120025. |
| MLA | [1] Ruoyu Wang, et al., "Extraction of Lithium，Rubidium，Cesium from Zinnwaldite by Low Temperature Alkaline Roasting-Water Leaching." Chinese Journal of Rare Metals, vol. 48, no. 12, 2024, pp. 1743-1754, https://doi.org/10.13373/j.cnki.cjrm.XY21120025. |
| APA | [1] Ruoyu Wang, Zhenping Cai, Xijun Tian, Pengfei Luo, & Song Chen. (2024). Extraction of Lithium，Rubidium，Cesium from Zinnwaldite by Low Temperature Alkaline Roasting-Water Leaching. Chinese Journal of Rare Metals, 48(12), 1743-1754. https://doi.org/10.13373/j.cnki.cjrm.XY21120025 |
| IEEE | [1] Ruoyu Wang, Zhenping Cai, Xijun Tian, Pengfei Luo, and Song Chen, "Extraction of Lithium，Rubidium，Cesium from Zinnwaldite by Low Temperature Alkaline Roasting-Water Leaching," Chinese Journal of Rare Metals, vol. 48, no. 12, pp. 1743-1754, 2024, doi: 10.13373/j.cnki.cjrm.XY21120025. keywords: {zinnwaldite;lithium;low temperature;alkaline roasting} |