Leaching Chemistry Of Alkali Roasted Ilmenite For The Extraction Of TiO2 And Rare-earth Oxides

Abstract:

The extraction and beneficiation of synthetic rutile has traditionally been carried out by using either via sulphuric acid leaching after slag smelting of titaniferous concentrates or, via slag smelting to better than 80% TiO2. Besides acid leaching, the lesser grades of TiO2 are also used for direct chlorination for the synthesis of high grade of titanium tetrachloride. These two conventional processing techniques for titaniferous materials have relied on the supply of high grades of heavy mineral concentrates.In the past we have reported the processing of ilmenite for the extraction synthetic rutile using alkali roasting and leaching, and we have shown that the extraction of synthetic rutile of purity more than 90 weight % TiO2. In this paper we aim to demonstrate the improvement in extraction chemistry leading to recovery of whiter grades of titanium dioxide with better than 95 weight percent purity. We propose a new methodology, which utilizes the low-grade titaniferous minerals for the extraction of synthetic rutile and also significant quantities of rare-earth elements. We demonstrate the alkali roasting of lower grades of mineral concentrates and subsequent leaching in an aqueous medium for preferential separation of white grades of TiO2 during controlled atmosphere leaching of alkali titanate. The paper specially examines the leaching chemistry, changes in the crystal structure, and the influence of temperature and pH on the composition of titanium-rich mineral phases formed. The analyses of phases were carried out using the X-ray diffraction, scanning electron microscopy, and XRF. The separation and concentration techniques for the rare-earth elements in the magnetic and non-magnetic fractions of ilmenite are also examined for reclaiming rare-earth elements at the front end of unit process.

Keywords:

Full Text:

Cite this article as: