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 Na2SiO3 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 CaCl2:Na2SiO3 is 1:1.5 at 1173 K and N2 atmosphere.
Highlights
Published: 28 December 2021Titanium is known as a strategic metal and as the “third metal” [1,2]
They contain a high-impurities contents of Ca and Mg [6,7], which is usually processed by the molten salt chlorination process in many titanium production enterprises in China [8,9,10]
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
Summary
Titanium is known as a strategic metal and as the “third metal” [1,2]. Titanium sponge and titanium dioxide chloride are key strategic materials that support the development of modern society [3,4,5]. There is a large amount of titanium resources in Panxi reign, China They contain a high-impurities contents of Ca and Mg [6,7], which is usually processed by the molten salt chlorination process in many titanium production enterprises in China [8,9,10]. The treatment of molten salt chlorination waste slag has become a serious problems in the molten salt chlorination process. The water-soluble method is the main method of treatment for molten salt chloride slag, but currently, research cannot radically solve the problem of molten salt chlorination slag, resulting in lower recycling efficiency, complex processes, and massive secondary waste generation [13]. The conversion of calcium-containing phases and their separation of NaCl are the key parts of this work, and they are systematically studied in this paper; thermodynamic analysis, phase transformation behavior, and calcium removal behavior are all investigated
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