Extraction process for reactive metal oxides

摘要

The present invention relates to a zero-waste process for extraction of alumina from different types of bauxite ores and red mud residues and of titanium dioxide from ilmenite. Iron oxide is first reduced to metallic iron above the melting point of C-saturated cast iron alloy which yields a high-C iron alloy and an Al and Ti metal oxide rich slag which is then treated with alkali carbonate to form alkali aluminates and titanates. The alkali aluminates are separated by water leaching from which the hydroxide of alumina is precipitated by bubbling C02. The residue from water leaching is treated with sulphuric acid and Ti02 is precipitated via a hydrolysis route. The process recovers most of the metal values and generates only small quantities of silicious residues at pH 4-5 which can be used for soil conditioning. The present also relates to a method for selective separation of Ti02-rich oxides from titaniferrous ore/residue materials via oxidative roasting in the presence of alkali carbonate or carbonates followed by aqueous leaching of the roasted material and selective precipitation of Ti02 under controlled condition below pH=4.

主权项

1. A process for recovering at least one metal oxide from a titaniferrous or aluminaferrous mixture comprising:
(A) preparing a molten slag, said molten slag is prepared by
(A1) melting iron with a composition of cast iron into a molten cast iron bath;(A2) adding said titaniferrous or aluminaferrous mixture to the molten cast iron bath;(A3) smelting the titaniferrous or aluminaferrous mixture in the molten cast iron bath to produce a molten slag,
whereby the iron present in the titaniferrous or aluminaferrous mixture is reduced to molten steel in the molten slag; (B) adding to the molten slag an alkali metal carbonate; (C) isolating molten iron from the molten slag to produce a residual slag; and (D) recovering the at least one metal oxide from the residual slag, wherein the at least one metal oxide is one or more of Al2O3, TiO2, Fe2O3, and SiO2.