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| Removal of calcium and magnesium impurities from molten salt chlorination slag by high-temperature phase transformation and recovery of sodium chloride |
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Received:January 27, 2025
Revised:June 06, 2025
Accepted:June 09, 2025
Published Online:April 30, 2026
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| DOI：10.3969/j.issn.1005-7854.2025.06.017 |
| KeyWord:molten salt chlorination slag;calcium and magnesium removal;high-temperature phase transformation;high-temperature filtration;sodium aluminate;reaction mechanism;sodium chloride recovery |
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| 1.School of Materials Science and Engineering, Xinjiang University, Urumqi 830000, China;2.Xinjiang Xiangrun Technology New Materials Co. Ltd., Hami 839000, Xinjiang, China |
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| Abstract: |
| Molten salt chlorination is a key process for treating high-calcium-magnesium titanium resources in China and plays an irreplaceable role in the production of titanium tetrachloride. However, the large amount of molten salt chlorination slag generated during this process has a complex composition, primarily containing corrosive components such as CaCl2 and MgCl2. Its efficient treatment and resource utilization pose significant challenges and have become a technical bottleneck restricting the green and sustainable development of the titanium industry. This paper systematically analyzes the physicochemical characteristics and environmental risks of molten salt chlorination slag and reviews the advantages and limitations of existing water leaching treatment technologies. On this basis, a high-temperature phase transformation–high-temperature filtration technology is proposed, focusing on the behavior and mechanism of sodium aluminate as an additive for removing calcium and magnesium impurities. The optimal process conditions were determined as follows: reaction temperature of 1 223 K, raw material-to-additive molar ratio of 1∶2, and reaction time of 30 min. Under these conditions, the removal rates of calcium and magnesium reached 98.41% and 99.55%, respectively, and the recovery rate of sodium chloride reached 69.50%. Kinetic analysis indicated that the reaction process is controlled by product-layer diffusion, and the reaction activation energy of calcium ions (16.17 kJ·mol?1) is higher than that of magnesium ions (3.72 kJ·mol?1), revealing the fundamental reason for the more challenging removal of calcium. This study provides a theoretical basis and technical pathway for the clean treatment and resource recycling of molten salt chlorination slag, holding significant practical implications for promoting the low-carbon transition of the titanium industry. |
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