The Conversion of Calcium-Containing Phases and Their Separation with NaCl in Molten Salt Chlorinated Slags at High Temperature

Feng Chen, Changlin Liu, Yuekai Wen, Fuxing Zhu, Hongguo Yao, Yufeng Guo, Shuai Wang and Lingzhi Yang
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Feng Chen: State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Sichuan 617000, China
Changlin Liu: State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Sichuan 617000, China
Yuekai Wen: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Fuxing Zhu: State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Sichuan 617000, China
Hongguo Yao: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Yufeng Guo: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Shuai Wang: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
Lingzhi Yang: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China

Sustainability, 2021, vol. 14, issue 1, 1-12

Abstract: The titanium resources in Panxi reign, China, have a high-impurities content of Ca and Mg, which is usually processed by the molten salt chlorination process. This process allows higher Ca and Mg content in its furnace burdens. However, there is a huge amount of molten salt chlorinated slag produced by this process, consisting of complex compounds and waste NaCl/KCl salts. These slags are always stockpiled without efficient utilization, causing serious environmental pollutions. To recycle the NaCl in the slag back to the molten salt chlorination process, a novel process to deal with those molten salt chlorinated slags with phase conversion at high temperature is presented in this paper. The calcium-containing solid phase was generated when Na 2 SiO 3 was added to the molten salt chlorinated slags at high temperature, while NaCl was kept as a liquid. Thus, liquid NaCl was easily separated from the calcium-containing solid phase, and it could be reused in the molten salt chlorination process. The conversion of calcium-containing phases and their separation of NaCl are the key parts of this work, and they have been systematically studied in this paper; thermodynamic analysis, phase transformation behavior, and calcium removal behavior have all been investigated. The calcium removal rate is 78.69% when the molar ratio of CaCl 2 :Na 2 SiO 3 is 1:1.5 at 1173 K and N 2 atmosphere.

Keywords: molten salt chlorinated slag; phases conversion at high temperature; calcium removal rate (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
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