A novel process for highly efficient separation of boron and iron from ludwigite ore based on low-temperature microwave roasting

A facile route for simultaneous activation and separation of boron and iron from ludwigite ore at low temper-ature under the synergistic effect of microwave heating and sodium carbonate (Na2CO3) was reported. It was shown that the composite system would absorb microwave energy well and promote the reduction of iron oxides and formation of water-soluble metaborate derived from szaibelyite, with restrained decomposition of lizardite which demanded less Na2CO3. After roasting at only 700 C, the metallized briquettes with iron metallization degree (eta Fe) of 90.5% were produced. By milling and leaching and subsequent magnetic separation of the metallized pellets, the boron-rich leachate with boron leaching percentage of 85.1% and direct reduced iron (DRI) powders with total iron content (TFe) of 90.6 wt%, eta Fe of 97.6%, and iron recovery (epsilon Fe) of 91.2% could be obtained. Boron and iron had much better separation performance than that achieved by the conventional route.

Automated summary

A facile route for simultaneous activation and separation of boron and iron from ludwigite ore at low temperature was developed using the synergistic effect of microwave heating and sodium carbonate. The composite system absorbed microwave energy well and promoted the reduction of iron oxides, resulting in the formation of water-soluble metaborate and the restrain of lizardite decomposition. The separated boron-rich leachate and direct reduced iron powders had superior performance compared to conventional methods.