snoman701 said:
I don’t especially like mixing my batches...mostly because without icp to know what’s there, I can’t track what I’m making.
snoman
first I want to say that when it comes to refining nothing could be more true then the old saying - "there's more then one way to skin a cat" --- in other words it comes down to personal preferred methods based on things like chems available, experience, types of material, etc.
Generally speaking we tell (new) members not to mix batches of material - as in don't go throwing a bunch of "different" material in a bucket full of acid & that is because a lot of different metal can be involved in the different material & different acids react differently with the different metals so you can end up making a "real mess" --- then also we tell (new) member to separate material by material "type" so they can get a handle on the process of that material type & as well get an idea of yield from that material type
After that - in my opinion (if I am working with
my own material) why would I not mix material if those mixed materials are all compatible with the same process
Example; - I have a batch of fingers (gold plate on copper) a batch of pins (gold plate on brass) & a batch of gold filled on copper & I intend to recover the foils from each of those batches using nitric to dissolve away the copper/brass
Why in the world would I run 3 different batches - wash the acid out of the foils (3 times) AR the foils (3 times) drop the gold (3 times) wash the gold (3 times) & melt the gold (3 times) --- when - because all that material is compatible to the same process I can run it all as one batch
In other words - after years of doing this I already have a reasonable expectation of "foil recovery" from each type so I can already calculate a reasonable total expected yield whether I run it as 3 batches - or as one batch
Now per the underlined in the above quote; - the only reason I would need an ICP (or AA) is if I am mixing a costumers material with mine so that I can account to the customer
Another words I would then need to keep the foil recovery separate - then AR the costumers foils - ICP it to give the customer an accounting --- then do mine - then mix the two so I only have to do 1 drop, 1 wash, 1 dry & 1 melt --- if I had an ICP - I don't so I do a costumers separate from mine
Now concerning using acids - why would I use fresh acid in a second process if I have usable acid left from a previous process - that makes no sense to me
Example; - I just got done with a batch of foil recovery from some fingers - then I also did an AR leach on some chip ash
Because I used an "excess" of nitric in my AR leach to "insure" all the gold was leached from the ash
Therefore - because I "know" the AR leach still had plenty of free nitric in it I then poured the filtered AR leach in a beaker with the foils to dissolve the foils
The point being - its all my gold - if I put all the gold in solution I am going to get all the gold back when I go to drop it - the question being --- why in the world would I use "fresh" acid to dissolve the foils when the AR leach still as plenty of acid in it to dissolve more gold --- seems like a waste of acid to me
I also worry about precipitation of gold with copper. Stannous becomes harder to read with that much copper in solution,
Why are you "worried" about precipitating gold with copper - using copper to "recover" gold from very dirty solutions has been a standard practice in large refineries forever - it was one of the first things I learned from people like Harold, 4metals, nickvc, & GSP when I first stated learning all of this something like 11 - 12 years ago & copper has been my "recovery" go to tool ever since
Copper (if its the primary metal in solution) is not going to mask your stannous test in fact it is far less likely to mask you stannous test then other metals (say like the metals in solution from doing a batch of ceramic CPUs)
and less reliable with excess oxidizer present.
Thats just not true - in fact that is one of the points to using copper "when there is an excess of oxidizer"
The copper uses up ALL of the oxidizer - which in turn then allows the copper to cement out ALL of the gold
if there is an excess of oxidizer - when you first put the copper in - it starts out as a redox reaction (reduction & oxidation taking part at the same time)
in other words - at first it starts to cement out the gold (reduction) but then because there is still free oxidizer it also re-dissolves the gold (oxidation) so both are happening at the same time --- but then - once the oxidizer is used up by the copper it then starts cementing the gold out as a "reduction" only process
That reaction will then take place until there is no acid left to dissolve copper - so when that reaction stops ALL of the gold has precipitated - pull the copper out - rinse it off & let your gold settle (along with stannous testing of course)
The only question is (remember we are talking a recovery process not a refining process) is how much copper contamination you end up with
In all my years of doing this (& well over 1,000 times) the very worst I have ever had my gold come back was 97 plus & I have had "a lot" of it come back as high a 99 - 995
When I was over in England & met with Jon, Goran, Nick, Pat & Deano - I did a batch of ceramic chips (pic) which gave me a VERY dirty solution with lots of free nitric (to insure all metals were dissolved)
I cemented that solution with copper - we hit the expected yield "on the nose" & XRF read out on the gold was 995
Kurt
:shock: :roll: 
