Cauldron Energy (ASX: CXU) has highlighted preliminary testwork results of over 96% uranium extraction using acid and carbonate/bicarbonate leaching methods on samples from its Bennet Well deposit in Western Australia.
Notably, the east recovery of uranium with low acid consumption indicates the potential for lower operating costs.
Site ground water analysis has also shown no deleterious elements present that may interfere with downstream processing.
In addition, XRF results show an increase in core assay grade of about 6% from the original ICP assay results while deconvolved gamma probe grade and assay grade differences have increased from 20% to approximately 25% with the latest XRF results suggesting an increase in the gamma results used to calculate the existing JORC resource.
QEMSCAN analysis has also identified coffinite, sodium zippeite and uraniferous zircons in the two samples submitted. The high uranium recovery rates suggests that all three uranium species appear to be soluble and easily recoverable.
"The uranium recovery percentages of up to 98.6% shows that the uranium in the Bennet Well Project is soluble and appears to be extractable using the in-situ recovery (NYSEMKT:ISR) type production method," Cauldron head of operations Simon Youds said.
"The high uranium recoveries show that the ISR method would be extremely effective and be a relatively cheap production method where uranium oxide will be economic at even the current low commodity prices.
"The fact that both the acid and alkaline leaching methods both worked on the two samples submitted to ANSTO, as well as potentially low acid consumption, is even more encouraging since Cauldron will then have options as to what the preferred method will be."
Cauldron noted the high extraction values obtained in both chemical environments, combined with anticipated low reagent consumption, encouraged it to continue developing the project.
Bennet Well Testwork
The leach testing on composited samples from drill holes YNDD018 and YNDD022 was undertaken at the ANSTO facility in New South Wales.
YNDD018 had a grade of 5.1 metres at 1,209ppm U3O8 34 core assay samples composited together for the leaching sample while YNDD022 had a grade of 1.1 metres at 473ppm U3O8 and a total of 10 core assay samples.
These were selected to complete the leach testing since YNDD018 represented the most sand dominated core hole drilled while YNDD022 was the most clay rich core hole drilled.
Analysis was completed on the total composition of each composite sample as well as water samples collected from the Bennet Well region to determine whether there are any elements present that would likely cause problems for ISR type mining.
Analysis showed calcium and magnesium were low, indicating that carbonate content should be low and hence acid consumption should also be low.
Of the other minor elements, none were at a concentration that would be expected to cause downstream processing problems.
Salt content in the site water analysis averaged 1270 mg/L and is therefore not expected to impact any ion exchange or solvent extraction processes in the solution purification and product precipitation plant.
Selected core pulp samples that had ICP (Inductively Couple Plasma) assays completed were re-tested by ALS using the XRF (X-ray Fractionation) method to determine whether the uranium had been completely digested in the ICP assays.
This resulted in an overall 6% increase in uranium oxide values when compared to the ICP assays, indicating that the ICP method is underestimating the true uranium oxide grade since not all of the contained uranium oxide is being completely digested.
The previously reported difference between the deconvolved gamma probe grades and ICP grades of 20% is now up to approximately 25% based on the XRF results.
Cauldron is continuing to work with Uranium Specialist Mr David Wilson to determine why the deconvolved uranium oxide values are significantly lower than the assay grades.
Preliminary assessment by Mr Wilson has shown that a moisture correction factor may need to be applied. A moisture correction factor is sometimes needed when there is a porosity >30% and is common in sandstone uranium deposits.
Cauldron is awaiting further porosity, density and permeability data from CoreLabs which are completing testing of the Bennet Well core samples.
Once this data has been compiled then an assessment can be made as to whether any further corrections are needed to bring the deconvolved gamma probe grades in line with the assay grades.
"The current Bennet Well Resource of 15.7 million pounds of U308 is based primarily on deconvolved gamma probe grades," exploration manager Mark Couzens said.
"With the recent findings that the gamma probe data is significantly underestimating the uranium oxide grades as seen in assay values then there is likely to be a considerable correction applied in the near future which could increase the current resource size and average uranium oxide grade."
Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) analysis was completed on one high grade core sample from both core holes submitted to ANSTO to determine the types of uranium present in the core samples.
The results showed that there were three types of uranium present in the two samples including coffinite, sodium zippeite and uraniferous zircons. The high uranium recovery rates suggest that all three uranium species appear to be soluble and easily recoverable using an ISR production method.
In late January 2014, comparisons of assay results from Bennett Well saw a 68.3% increase in uranium grade width in the main mineralised zone from the gamma probe data.
An upgraded Resource estimate is likely to be received in the second quarter 2014 from the current JORC Inferred and Indicated Resource of 15.7 million pounds of eU308 at 270ppm.
Bennet Well is part of the 1,930 square kilometre Yanrey Project located about 85 kilometres south of Onslow that is adjacent to Paladin Resources' (ASX: PDN) Manyingee deposit that has an Indicated Resource of 17.8 million pounds of U308.
Like Manyingee, Bennet Well is expected to be amenable to ISR mining.
Studies indicate that average grades of above 250ppm eU308 over 1 metre are potentially economic for an ISR mining operation.
Exploration has identified 11 major palaeochannels, most with evidence of uranium mineralisation. Yanrey has an Exploration Target of between 30 million and 115 million pounds of U308 at grades of 250ppm to 900ppm.
There is potential for regional annual production of 5 million pounds uranium using ISR at low costs, high margins and low environmental impact.
Access is granted via the Great Northern highway and along the Twitchen road to Onslow.
Today's results are value accretive for Cauldron and we expect that the $0.08 share price and circa $13 million market cap to get a leg up.
The high uranium recoveries and use of in-situ recovery (ISR) production method is a significant differentiator for Bennet Wells and Cauldron, providing a low cost production option that could produce a uranium oxide that would be economic at even the current low commodity prices.
With high uranium recoveries and low acid consumption, the testwork carried out by ANSTO on samples from Cauldron's Bennet Well uranium deposit highlights the potential for lower operating costs.
An upgraded resource from the current Inferred and Indicated Resource of 15.7 million pounds of eU308 at 270ppm is also looking likely with recent findings that the gamma probe data is significantly underestimating the uranium oxide grades.
Investors now have the Resource update in the second quarter to look forward too.
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