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| Study on Phase Equilibrium of Nb2O5-Al2O3-MgO-Na2O-CaO-SiO2 System |
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Received:April 24, 2023
Revised:May 06, 2023
Accepted:May 08, 2023
Published Online:September 04, 2023
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| DOI：doi：10.3969/j.issn.1007-7545.2023.10.008 |
| KeyWord:niobium resource; phase balance; mineral phase transformation; Nb2O5-Al2O3-MgO-Na2O-CaO-SiO2 |
| Author | Institution |
| CHEN Chang |
长沙矿冶研究院有限责任公司 |
| REN Guoxing |
长沙矿冶研究院有限责任公司 |
| HAN Wensheng |
长沙矿冶研究院有限责任公司 |
| RAN Mengjie |
长沙矿冶研究院有限责任公司 |
| CHEN Wen |
长沙矿冶研究院有限责任公司 |
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| Abstract: |
| In order to reveal directional crystallization rules of niobium minerals in Nb2O5-Al2O3-MgO-Na2O-CaO-SiO2 multi-component slag system, the influence of calcium-silicon ratio (CaO/SiO2), Nb2O5 content and temperature on phase balance of slag was investigated by the high temperature equilibrium, cold quenching, SEM-EDS/XRD/EMPA method. A dominant phase diagram for the crystallization of niobium-containing minerals was constructed. The results show that three niobium phases are found in the system, it is Ca2Nb2O7, Ca(14-x)Nb(2+x)Si8O(35+1.5x) and 3CaO?MgO?Nb2O5 respectively; Niobium is enriched in the liquid phase first, and compared with the gangue components, the niobium-containing solid phase is the later precipitated phase; With the increase of CaO/SiO2, the dominant interval of the niobium-containing solid phase changes from Ca2Nb2O7 phase to Ca(14-x)Nb(2+x)Si8O(35+1.5x) phase, and then to 4CaO?MgO?Nb2O5 phase. The dominant crystallization range of Ca2Nb2O7 phase is temperature at 1 050—1 200 ℃ and CaO/SiO2=0.8—1.2. The intercalation mass concentration of Nb2O5 in the Ca(14-x)Nb(2+x)Si8O(35+1.5x) phase is between 18.5% and 19.5%. |
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