However, there is increased recognition that ISL field leach trials provide more reliable, large scale tests of recovery.
In addition, these trials also provide important data on the hydrology and permeability of the sands which host mineralisation. These are important parameters for mineral resource estimates.
For most ISL operations, overall uranium recovery factors are commonly of the order of 60-70%. Higher recovery factors have been reported for ISL operations in Kazakhstan. The reporting of these recoveries in Ore Reserve reports is necessary to provide all the material information required by interested parties to understand the public report and ensure that the estimate is presented in a transparent manner.
The reporting of recovery factors in mineral resource reports is encouraged as in these deposits, “information on estimated mineral processing recovery factors is very important” and improves the understanding of the basis for the Competent Person’s assessment that the deposit has reasonable prospects for eventual economic extraction.
The Competent Person is required to classify the estimates according to the resource categories defined in the JORC Code. This process is equally applicable to estimates of ISL uranium resources as for any other type of deposit.
The categories are assigned after considering a range of geological and hydrogeological aspects, drillhole spacing, method and accuracy by which the grades were determined (eg assays, gamma ray probes and/or PFN tools), and other factors.
The following general guidelines have been applied in classifying ISL uranium resource estimates in recent years:
1. Where grades are based solely on poorly calibrated historical gamma data, with no corrections for disequilibrium, the estimates, at best, may be classified as Inferred Resources. For the use of historical poorly calibrated gamma data alone there needs to be some control of the gamma data with some core holes (or at least chips) to confirm the mineralogy that is the source of the gamma signature.
2. Where historical data is supported by properly calibrated grade data (gamma and PFN), the estimates may be classified as Indicated Resources, subject to holespacing, geological continuity and disequilibrium considerations for gamma ray probe measurements.
3. Where the grade data are well calibrated PFN data, subject to demonstrated continuity, hydrological aspects of the sediments are adequately understood, estimates could in principle be classified as Measured Resources*.
However in practice, for the only Australian deposit that has been completely drilled by *PFN tool,* the Competent Person classified the estimated resources as Indicated Mineral Resources (refer Honeymoon estimate August 2006 as previously described).
*PFN tool:* Prompt Fission Neutron.
This from the "The Activist's Guide To Uranium Mining."
The density of drill hole spacing determines the level of confidence for the size of the deposit and the category, under which the deposit is reported (measured, indicated, or inferred). The exploration companies usually define resources conforming to one or more of these standards:
Not sure what others are thinking, but it might be safe to assume that Section 2 is where we are currently at (how far in I don't know), attempting to drill the holes (now possibly slowing) more closely to each other. On top of that there's the gamma ray probing. Unless someone knows the answer, the time this all takes is open to conjecture. But I suppose it all depends on what we discover and how many more holes need drilling.
http://www.jorc.org/pdf/uraniuminsitu.pdf
PEN Price at posting:
4.2¢ Sentiment: Hold Disclosure: Held
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