Iron Impurity Removal from Bauxite Ore:A Comprehensive Review of Pyrometallurgical, Hydrometallurgical, and Physical Separation Methods

Bauxite is the world's principal ore for aluminium production. However, its prevalent iron oxide impurities hematite, goethite, and magnetite-pose critical challenges to the efficiency of the Bayer process, the quality of alumina and high-grade refractory products, and the environmental management of red mud. With global bauxite grades declining and demand for high-purity alumina rising, the development of efficient iron-removal strategies has become a paramount research priority. This paper presents a comprehensive, critically evaluated review of all major iron-removal methodologies: pyrometallurgical routes (classic magnetic roasting, hydrogen-suspension roasting, microwave-assisted roasting, reductive smelting via the Pedersen process, and pyrite-assisted reduction), hydrometallurgical routes (hydrochloric, sulfuric, and organic acid leaching; bioleaching with Paenibacillus polymyxa and Aspergillus niger; and combined reductive-complexing methods), and physical beneficiation techniques (high-gradient magnetic separation, gravity separation, and flotation). For each method, reaction mechanisms, thermodynamic and kinetic data, optimal parameters, and reported iron-removal efficiencies are discussed. A structured comparative analysis of technical performance, energy consumption, alumina recovery, and environmental footprint is provided, together with selection guidelines for different bauxite types. Particular attention is given to diasporitic karst bauxites of the type found in Iran's Jajarm deposit. The review identifies the hybrid hydrogen-roasting plus magnetic separation route as the most promising technology for low-carbon, high-efficiency iron removal, while organic-acid selective leaching offers a complementary route for moderate-grade ores.

کلیدواژه ها:

bauxite ، iron removal ، magnetic roasting ، Bayer process ، hydrometallurgy ، selective leaching ، red mud ، bioleaching ، refractory grade ، diasporitic bauxite