angela_li - 24-12-2007 at 17:23
Hi
I was told H2S04 will not dissolve silver, but in my test. I did an XRF test on the ore and found traces of Ag. I milled my mixed oxide and sulphide
ores together to 50 micron then used dilute sulphuric acid. After leaching for 3 days the XRF showed no Ag in the ore. Could it be true the Ag is
in the leached solution?
Thanks
Angela
not_important - 24-12-2007 at 17:43
Do you know what chemical form the silver is in? While sulfuric acid does not attack silver in the cold, it can react with silver sulfide. Check
tables of chemical properties, and mineralogy books for the common forms silver is found in.
Xenoid - 24-12-2007 at 18:24
It depends a bit on quantities and concentrations, Ag2SO4 is slightly soluble even in H2O (0.8g/100g) and Ag2S slightly so. How much Ag was there to
start with (XRF will easily detect <10ppm)? As a ?geochemistry student you must be aware that many of the earths ore deposits were formed by simple
transport of elements from a huge volume of rock, in the form of dilute solution in super heated H2O and deposited in veins at points where there was
a sudden drop in pressure(eg. even gold is quite soluble under these conditions). I wouldn't at all be surprised if a relatively large quantity of
sulphuric acid was able to remove a small quantity of Ag from material ground to 50 microns.
angela_li - 27-12-2007 at 19:50
Thanks "not_importand" and "Xenoid" for answering.
I am only using between 1 - 1.5% dilute H2S04, it's not very high. I believed the silver came from the sulphide ore, but I have no proof. From all
my searches it cannot come from the oxide ore. Am I correct on that?
Thanks again.
Angela