Vanadis Battery Metals, page-7

This is a post from Dave85 on LSE. Another investor who is pro Aura Energy so thought I would share...

Just read and wanted to point out this article. Found it very interesting and likely apt for Haggan, its well worth a full read but I’ve included a few excerpts.

Article link

https://www.researchgate.net/publication/322321004_Vanadium_Extraction_from_Shale_via_Sulfuric_Acid_Baking_and_Leaching/download

Excerpts from A (linked article) & RNS (RNS 25/10/18 link below)

http://www.lse.co.uk/share-regulatory-news.asp?shareprice=AURA&ArticleCode=t070fy89&ArticleHeadline=Haggan_Vanadium_Project_scoping_study_update

The numbers in the article excerpts are references at the end of the article.

A 'shale is another important vanadium-bearing primary resource in China.1,5 Vanadium exists primarily as trivalent vanadium (V(III)) in shale'

A 'V(III) is the most difficult to extract as it readily replaces Al(III) from the dioctahedral structure as an isomorphism of muscovite or illite.'

This is what we have at Haggan. The V(III) has partially replaced the Al in muscovite to give roscoelite (K(V3+, Al, Mg)2AlSi3O10(OH)2). To my limited understanding anyway.

Just compare the chemical symbol with that given in the linked article for pure muscovite (KAl2(AlSi3O10)(OH)2) its very similar but with V(III) and maybe some magnesium. To me this suggests the results discussed in the article are potentially and likely relevant to the material at Haggan.

RNS ‘Vanadium deportment was characterised and shown to be present in the V(III) valence state, hosted in the mica mineral roscoelite (K(V3+, Al, Mg)2AlSi3O10(OH)2)’

A 'Following the now obsolete technique of salt roasting-water leaching, acid leaching technologies, including roasting- acid leaching (RAL), direct acid leaching (DAL), and pressure acid leaching (PAL) have been adopted to extract vanadium from shale in the past decade.7–11 RAL and DAL are inefficient for vanadium extraction from the crystal lattice of the aluminosilicate minerals unless high amounts of acid are used, and, in most cases, fluorides (CaF2 and HF) are added to enhance vanadium extraction from shale'.

This creates lots of contaminated water which is expensive to clean.

RNS ‘Oxalate salt roast with acid leach tests showed up to 59% vanadium recovery. Calcination with acid leach showed up to 32% vanadium recovery. Acid pressure leach showed up to 61% vanadium recovery on fresh ore material that had not been subjected to any beneficiation.’

Aura have expressed in the past PAL was the preferred technique.

AIMO ATB

A 'PAL process requires large capital investment, which limits its industrial applications. Therefore, the sulfuric acid baking– leaching (SABL) process was proposed to extract vanadium from shale,14 which has advantages of high extraction efficiency, short processing times and no fluoride addition.’

A ‘The shale used here was obtained from Teng-da Mining’ ‘China. The chemical composition of the shale as determined’ ‘from the x-ray diffraction’ ‘were quartz, muscovite, pyrite, and calcite. The chemical phases of the vanadium in the shale were analyzed’ ‘The results showed that 88.11%, 10.03% and 1.86% of the total vanadium existed in silicate minerals, organic matter, and free oxide, respectively.’

This shows that the vast majority of the Vanadium in the mica in the sample used in the article was successfully extracted. Aura have said about 40% of the Haggan samples investigated were mica minerals (https://www.vanadisbm.com/project) and that the mica is where the vanadium is contained. 

A ‘Anhydrite peaks were observed in Fig. 2a after baking with a sulfuric acid dosage of 15 wt.% while the calcite peaks completely disappeared, indicating that calcite can be easily converted into anhydrite in the presence of a small amount of sulfuric acid. In this case, only 13.6% vanadium leaching efficiency was obtained as the sulfuric acid reacted primarily with calcite in the shale and very little vanadium occurred in calcite phase’

RNS ‘ Evaluation of beneficiation by flotation of mica minerals and rejection of calcite at ALS Laboratories, Burnie Tasmania. This work demonstrated best preliminary results of 83% of vanadium could be recovered to 64% of total mass, resulting in a beneficiation factor of 1.3 times (sample: DDH022). Additionally, rejection of 80% of calcite was achieved in this preliminary work (sample: DDH022). This calcite rejection will reduce acid consumption and operating costs.’

AIMO ATB

 

The article concludes….
A ‘In the studied shale, 88.11% of the vanadium was contained in aluminosilicate minerals, which are difficult to extract. However, vanadium recovery can be enhanced using the SABL process. The sulfuric acid diffused into the shale and was then concentrated by water evaporation at 200C. The dehydroxylation of muscovite was accelerated in the anhydrous system; meanwhile, K, Al and V in the muscovite were sulfated by reaction with active [SO4 2], releasing the vanadium. Hence, the vanadium was efficiently extracted from shale using the SABL process, which does not require the use of fluorides, minimizing fluoride pollution and wastewater. On the basis of the phase transformations, a reaction scheme for muscovite decomposition, which is closely related to vanadium extraction, was proposed. Furthermore, the thermodynamic analysis showed that the muscovite can be more easily destroyed in the SABL process than in the sulfuric acid leaching process in aqueous solutions.’

A ‘Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale’

I know doing it in the lab is completely different to doing it at a mine or even at a lab at scale but reading this it certainly came over as positive and shows the potential of very good recoveries of vanadium in low grade shale deposits. SS will be a good read, I wonder if some consideration of this SABL technique will come in at some level of study/feasibility. Capex reduction seems a possibility as compared to PAL and my reading I mentioned in my 01/06/18 post here with very similar and high recovery rates.

New website looks great btw only had a quick look so far.

AIMO ATB