Ann: TNG signs strategic HoA with BBI Group, page-247

The complete utilisation of titaniferous magnetites has been a pipe dream since people first started utilising vanadium in steelmaking. If we take the pyro route, such as the biggest players in PRC, ZA and former Soviet bloc countries have done, the iron is recovered via rotary kiln pre-reduction followed by electric furnace, or in the case of a few specialisesd producers, via a modified blast furnace process. The melt is then re-oxidised to evolve a vanadium slag. That slag contains 15-22% V2O5. It gets stockpiled for later roast-leach recovery of vanadium, or sometimes put in a thermite bomb to make crude master alloy, although the quality of the FeV by that route is poor. We refer to the slag route of production as co-production or secondary production. It’s how the major players can dominate supply at their whim. The titanium is discarded in the first steelmaking slag. It’s not economic to take the titanium from that slag. If the titanium in the feed is greater than 25%, then an incomplete reduction sorel process can be used, like Richards Bay. That makes iron and titanium slag that can be processed further. The paradox there is that if any vandium was present, it does get reduced into the melt and gets wasted to slag - generally the vanadium grades of such ores is poor to start with anyway. Pyro thus gets only two products, depending on the ore. Pig iron plus economic vanadium slag OR pig iron plus economic titanium slag.

The primary route requires exceptional ores. A concentrate of 1 to 2% V2O5 is produced via grinding and magnetic or gravity separation (the front end of the Mt Peake process has this in common with other primary producers). Grade and mass recovery are king as up to a third of the total energy costs occur here. If it’s low grade, enormous tonnages have to be mined, milled and processed to make concentrate. The most significant problem contaminant is silica. Some ores just can’t be easily processed to remove silica. Most of the yilgarm region deposits are also deeply oxidised, so magnetic recovery is poor and heaps of silica gets pulled through to the concentrate - that’’s why Windimurra fails time after time. The magnetic recovery was poor, low head grades and contaminated concentrate. Windomurra cant function at less than $5/lb pentoxide price (I suspect its break even point would be much higher at today’s energy and reagent costs)

The primary route passes the con through a roaster with any salt of sodium under slightly oxidative conditions. The vanadium solubilises into sodium vanadate which is very soluble. About 20% of the vanadium is not recovered during solubilisation. The roasted material, or calcine is passed though Hot water to make an aqueous vanadate liquor. Any silica gets taken out by addition of aluminium sulphate. The deailicated liquor is buffered and in the AMV route, under alkaline condition. Ammonium sulphate is added to precipitate ammonium metavanadate. The AMV is de amminated in a kiln to make pentoxide or trioxide. That product can be fused for sale or processed further into ferrovanadium in an aluminothermic process.

Roast-leach recovers only vanadium but it does it very well. The leached residues contain iron and titanium, but they are useless. Full of sodium and other crap, which steelmakers don’t want.

There are no free lunches in thermodynamics. Any process that tries to extract more, does so at a cost whether it’s the extra heat or reagents. The only thing that might be improved is unit efficiency. Conventional processes will always be more “bankable”