This discussion goes back to a statement by luckymjohnson which...

This discussion goes back to a statement by luckymjohnson which stated "I am no chemist, but fail to understand how the ore coming in can be 1600ppm, but the waste coming out only 500ppm"

The dispute is whether luckymjohson is correct in doing this comparison of ppms. That is all. I suggested that you cannot compare these two numbers based on the information in the article.

As I have said before, you cannot simply convert the 0.16% of thorium in the ore into 1600ppm by moving decimal places and say that this is an equivalent method to that used to obtain 500ppm of thorium in the waste solution.

We do not know how the 0.16% and 500ppm where estimated.

If you just used Mass/Mass then they should be different simply because one is referenced to the mass of the ore, while the other is referenced to the mass of the waste solution.