Recycling Excessive Alkali from Reductive Soda Ash Roasted Ludwigite Ore: Toward a Zero-Waste Approach
2020
Zhu, Zhongping | You, Jingxiang | Zhang, Xin | Li, Guanghui | Wang, Jian | Luo, Jun | Rao, Mingjun | Peng, Zhiwei | Jiang, Tao
During the soda ash calcining of ludwigite ore, sodium magnesium silicates are generated accompanying the activation of boron. This leads to the excessive consumption of soda ash and in turn environmental pollution of an alkali-rich residue. Aiming to reveal the mechanism of alkali recovery, Na₂MgSiO₄ was synthesized, characterized, and its water leaching behavior was investigated. Thus, a route for the value-added utilization of ludwigite ore was established and verified. For water leaching followed by magnetic separation of reductively soda ash roasted ludwigite ore, 96.97% Na₂O and 96.86% B₂O₃ were extracted into the leach liquor at a leaching temperature of 200 °C and a liquid-to-solid mass ratio of 8:1. Subsequently, 95.15% iron was recovered as powdery metallic iron by magnetic separation from the leached residue, while nonmagnetic material consisting of MgO, Mg(OH)₂, and Mg₂SiO₄ can be used to prepare magnesia-based refractories.
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