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Abstract <p>As the main method of alumina production in the world, Bayer process emits a large amount of high alkaline red mud, which poses a very serious threat to the ecological environment. In this study, the high-temperature calcification transformation method based on source blocking was used to treat the Guinea gibbsite from the perspective of mineral phase reconstruction. A new type of structural red mud with almost no alkali was obtained while achieving efficient dissolution of alumina at high temperature. Single-factor tests (180–280°C, C/S = 1.25–2.5, 60 min, 240 g L<sup>–1</sup> Na<sub>2</sub>O) showed that temperature and CaO/SiO<sub>2</sub> ratio jointly control extraction yield and Na<sub>2</sub>O content of the residue. Characterization revealed that rising temperature converts boehmite to well-crystallized hydrogarnet while suppressing sodium aluminosilicate. Al<sub>2</sub>O<sub>3</sub> dissolution increases from ~76% at 180°C to ~88% at 260–280°C; excess CaO drops yield. Na<sub>2</sub>O in slag falls continuously with higher C/S, reaching 0.41 wt % at 280°C and C/S = 2.5. The optimum compromise among yield, energy and equipment pressure is 240°C, C/S = 2.0, 60 min, giving 85% Al<sub>2</sub>O<sub>3</sub> extraction and &lt;0.8&#xa0;wt % Na<sub>2</sub>O in residue.</p>

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Phase Transformation and Process Optimization for High-Temperature Calcification Dissolution of Gibbsitic Bauxite

  • 期刊论文

  • 发表日期：

    2025年12月1日

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  • Zhiguo Li,
  • Wang Song,
  • Tingan Zhang,
  • Lv Guozhi,
  • Xin He,
  • Zhuangzhuang Yun

摘要

Abstract

As the main method of alumina production in the world, Bayer process emits a large amount of high alkaline red mud, which poses a very serious threat to the ecological environment. In this study, the high-temperature calcification transformation method based on source blocking was used to treat the Guinea gibbsite from the perspective of mineral phase reconstruction. A new type of structural red mud with almost no alkali was obtained while achieving efficient dissolution of alumina at high temperature. Single-factor tests (180–280°C, C/S = 1.25–2.5, 60 min, 240 g L–1 Na2O) showed that temperature and CaO/SiO2 ratio jointly control extraction yield and Na2O content of the residue. Characterization revealed that rising temperature converts boehmite to well-crystallized hydrogarnet while suppressing sodium aluminosilicate. Al2O3 dissolution increases from ~76% at 180°C to ~88% at 260–280°C; excess CaO drops yield. Na2O in slag falls continuously with higher C/S, reaching 0.41 wt % at 280°C and C/S = 2.5. The optimum compromise among yield, energy and equipment pressure is 240°C, C/S = 2.0, 60 min, giving 85% Al2O3 extraction and <0.8 wt % Na2O in residue.