Abstract
Titaniferous magnetite deposits are a significant source of vanadium for use in high strength steel alloying and other chemical applications as well as producing titanium slag for the chloride production of titanium pigment. The mineralogy of the deposits varies markedly and the ore characteristics strongly influencing the process route selected and the metallurgical outcomes. Characterisation of the ores reveals the presence of magnetite, ilmenite and other unique vanadium minerals such as spinel hematite and goethite with variable degrees of weathering along with weathered products of host rock. The standard processing route was to crush, grind and magnetically recover a concentrate for salt roasting to produce a soluble vanadate.
Beneficiation options are restricted, and generally focused on producing a combined iron and titanium rich concentrate containing vanadium due to the fact that ilmenite and magnetite and their products of weathering are magnetic and have similar specific gravities making their separation difficult. The ilmenite usually contains low levels of vanadium making its separation highly desirable from the iron mineralisation containing higher levels of vanadium. Magnetic separation is the standard route to produce concentrates.
Salt roasting to extract vanadium followed by water leaching has been the standard processing route for many years and this locks up the titanium in a glass phase. The cost of suitable sodium salts, availability of capital and increasing energy costs and energy availability are critical factors in determining the viability of aspiring vanadium producers. Alternatively smelting of concentrate to produce pig iron and titanium slag is also used where the vanadium can be recovered in a slag from the pig iron.
In this paper, factors influencing the recovery of vanadium are reviewed and emerging processing trends explored. The work done to produce titanium rich concentrates exploiting differences in magnetic susceptibility and new hydrometallurgical routes to produce separate vanadium, titanium and iron oxide products are discussed. The growing demand for vanadium electrolyte in Redox Flow Batteries now adds another value added product which can assist vanadium project economics. The important aspects of the processing of titaniferous magnetites have been condensed from the literature, published works, company websites, our own testwork and personal communication covering a range of titaniferous magnetites.
Reference is made to a number of historical projects and future projects covering traditional process flowsheets and new technology process flowsheets such as TIVAN where titanium pigment, iron oxide and vanadium pentoxide are recovered.