@Nodferatu
You make an interesting observation in your post.
I also get alarm bells ringing when I see the results from metres 18-20 and 20-22 in hole TERC-007 side by side.
Both results come from material that is described as “fresh dolerite” but one sample indicates a first pass recovery of gold of 49.3%, whilst the other only gives a first pass recovery of 7.8%. Considering the premise is that the gold is very very finely locked up in the rock in some weird homogeneous ionic form, this result seems to show that the extraction process contains a large degree of unreliability when it comes to extractable gold.
Secondly can anyone answer me this.
Why do the second pass “slag” results seem to yield the gold in much greater proportion? From what I understand the slag extraction/assay process arrives at the slag gold results by using a second melt and going through the same processes. Why would the process be any better on the slag melt than on the original fresh rock melt. Surely all that would be involved in maximising the fresh rock melt would be the addition of more flux. Why is the slag different? Why does the slag melt yield the vast amount of the gold when the fresh rock melt doesn’t?
Going by
@plough ‘s calculations on the energy cost surely a double melt wouldn’t make much difference to a single melt. Job done.
My concern is also with the use of silver as a flux. The results in which they get good first pass gold recoveries rely on adding an unspecified amount of silver to the melt, which they say in most cases is not recovered in the process. There seems to be a clear relationship between the amount of gold won on the first pass melt and silver being lost.
From what I can see of the assay process, the grade of gold is back calculated from the weight of the “gold” button recovered and the original weight of the sample. Where have they proven to us that the silver that is lost in the process is not partially finding its way into the “gold” button. From the start I was always curious as to why the extracted metal buttons didn’t have a rich gold colour. Gold pales to a whitish-yellow with the addition of silver. I would feel a lot more comfortable with the results if these buttons where sent to an independent laboratory to have their metallic contents determined and also if they could give more explanation about the second stage recoveries on the slag and why and how the gold is being recovered in much greater proportions from the slag but not the first melt. Esh
