Originally posted by Krum
Hi All,
The Table of results upon which this entire ASX Release is based (and this resulting thread) makes no sense to me. Worse, because it makes no sense it reflects poorly on the competence of the company, its Board, its geologist etc. And then to proceed to more bulk samples makes no sense?
The only things we have to go on are the Table itself, plus the 4th bullet in Key Points ("Results...........returning encouraging (Gekko Plant) 2,04 g/ton of Au average") - what does this mean? Head grade, tail grade, con grade? Statement above the Table: "An average grade of 2,04 g/ton of gold was obtained........in a total of a bit more than 89 tons." both seem to say that 2.04g/t gold was recovered, but from where.
JORC Code Table 1 attached should provide sufficient detail to understand the details, it speaks to this under "sub-sampling techniques and sample prep", and "Quality of assay data and lab tests" which basically say that they took roughly 14t bulk samples, sub-sampled 50kg, crushed and sub-sampled 1kg for lab analysis. These 1kg samples were sent for (what looks like BLEG - bulk leach of economic gold). The remainder of the bulk sample went through the Gekko plant to make Dore.
The table apparently compares two (really poorly defined) gold grades, and as it also includes two (again poorly defined) weights it is normal to assume they relate to each other. But then there should be two different lab analyses explanations but no.
But the main thing is that I would expect from either cyanide leach or gravity that the grade recovered in the con wold be circa 10 times higher (one order of mag) higher than the bulk feed grade??
So how to understand this protocol and the Table? Well first thing is that the gold is obviously nuggety (whole area is hence no JORC and cant drill accurately) so a nuggety approach to sampling and analysis should be taken.
We already know this and they say as much in the JORC Table. Also the grade of BS09 is 2 orders of magnitude higher than the other bulk samples and the picture of the panned gold shows visible gold.
I'm not even going into trying to discuss how the table should be setup (what other columns it should contain is basically the entire mass balance) because its too full of errors. For instance, did the plant only recover the same grade as was fed to it (2.04 Vs 2.48 g/t) if so that is terrible, or is this somehow a back calculated head grade from the bleg test? But if you look at the individual results 4 of the 6 went up by 1 order of magnitude (which I would expect from a gravity plant) suggesting its actually a comparison of Head grade to concentrate grade but then its comparing a leached con grade to (and where is this) the grams of dore recovered. But then one of the results BS05 has the same grades and one BS09 has 10.4 Vs 2.87g/t.
Two of the results are completely overwhelming the other 4 so the averages cannot be compared due to either poor sampling or analysis (basically poor approach and poor data provision). So the Table is meaningless, as certainly the headline statement of the 2.04 and 2.48 are meaningless as their definitions and context make no sense.
So, whats wrong? Well for one the taking of representative samples is incredibly difficult in nuggety ore - 50kg from where in the 14t?
And then sample prep (crush/grind), with soft visible gold its very easy to lose it in the crusher and grinder as it smears on the metal surfaces - did they sand clean the equip befoe and after to ensure no contamination and full recovery?
And the analysis, it only tells us they did a cyanide leach and how the result of that was returned (Atomic Adsorbtion) but how was the head grade of the bulk sample analysed. This is normally analyses by pulverising and leaching say 3grams. Sometimes a screen fire assay and a fire assay is used??
It all makes no sense to me so doing more sampling seems silly?
KRUM
I'm replying to my own post because I can't stop thinking about this ASX Release (thinking I must have misread it) and I've reread it to try to understand it. I now feel its worse than I thought because I studied it a bit more and found more info and made more logical connections:
Firstly, I missed this last time, but Figure 4 actually shows some grades and tonnages annotated to each Bulk Sample location (I just can't bring myself to use BS). (Would have been nice to have these annotations visible). So these annotations should logically represent the grades of the Bulk sample generated from sub sampling and lab analysis, but they are the grades from the Table titled Plant Recovered.
This merely confirms what I thought in last post that the ASX Release is suggesting that because the averages at the bottom of the two grade columns in the Table are similar that somehow that's good? Aka somehow that they got some correlation between what the actual lab analyses (from leaching of 1kg from 50kg taken somehow from the 15kg bulk samples) returned, to what gold Dore they recovered from the plant then divided back into the weights fed into the plant.
So, noting no discussion of how this (back calculation to derive the Plant Recovered grades) was done in JORC Table 1, I can only assume that they poured Dore from each Bulk Sample and then figured out that as a g/t contained in the 15tons from where it came through the plant.
Well I posted in my earlier post how tricky it is to get good results for sampling and analysing just the Bulk sample, especially the dual issues of first getting a representative 1kg sample from the 15tons, and then the possible losses and contamination in the crushing of that sample even in the lab and I also didn't discuss the amount of gold left behind after the leaching was completed?
Imagine how difficult it is to get that level of QC/QA for a bulk sample going through the plant: Look again at JORC Table 1 "Sub-sampling" last bullet which discusses the plant components it goes through and ask yourself could each separate bulk sample be put through that without cross-contamination and losses - noting you would literally have to pull apart and clean out the entire circuit before every bulk sample to be accurate.
What about the tails - what grades etc. There is just no way these poured Dore weights divided into the 15ton sample weights can return anywhere near accurate head grades that could be compared with lab analyses of poorly representative grab samples from the same bulk samples.
But even after all that, those are still just basic operational process and sampling issues a technician should understand, but I lose my mind with the basic underlying rationale behind this test and the conclusions drawn from the Table generated. This is the real issue here - competency - the fact that this nuggety issue is not recognised, that then the averages of the two grade columns can some how be compared when there is obviously such divergent individual results, and finally that because this comparison is somehow good.
It even amazes me some of the minor things, like for instance using a comma in the 2,04 g/ton, and the mixing of metric and imperial (grams and tons and g/t) and even in the Table the number of decimal points (one is an exact 10ton and the others all to 2 decimals, same with other columns - JORC actually defines (well certaimly for resources and reserves) the number of decimals according to the number of significant figures) and even though OGX don't operate with official JORC Resources, they are still legally obliged to release their numbers according to the JORC Code.
Sorry - I just can't get over this ASX Release - because somehow it trys to say that because 2.48 from the lab is close to 2.04 from the Plant Recovered and I just cant understand how that could be at all accurate? And wouldn't it be better to focus on plant recovery etc and say the plant recovered 80% of the gold or some such statement. I think you can understand why a process plant isn't used to sample and analyse head grade.
The plant should be used to see how well each component works on bulk samples, so sub samples from before and after each piece of equipment, and their rates of throughput are measured and a mass balance developed. Thats what should be releases and discussed. Isn't there a specialty plant manager onsite?
Who writes the ASX Releases and checks the statements? Note specifically the Competent Person statement says that the Information in the announcement is based on information provided by the CP - doesnt mean the CP actually made the statements and conclusions? Is the CP reviewing the statements and does he have the power to revise them?
In all honesty I hope I haven't missed something or got something wrong, and this is all only in my opinion so please make your own conclusions based on your own review.
KRUM
