ahmadbayoumi
I posted
Per the underlined - IMO (In My Opinion) - you really need to look into cyanide leaching
It will solve "all" the problems in red
Edit to add; - it will also reduce your waste by "A LOT" over that of using acid methods - plus in the end you will have the bonus of your copper/brass as a by product
You replyed
Actually, I didn't have the chance to work with cyanide before.
May be due to the danger associated with it .. don't know
So I don't know anything about the cyanide leaching process so seems it's not one of my options yet .. maybe later
You seem to have your heart set on dissolving LARGE amounts of pins with nitric (10s of Kg) --- but - because the LARGE volume of pins you are talking about also has the problem of producing LARGE amounts of NOx which need to be dealt with - which you can certainly do --- BUT --- setting up to deal with the NOx on such a scale is in it's self going to require a "fair" size investment & work
AND it's not just the NOx you have to deal with--- you are also going to produce a HUGE amount of chemical waste (copper nitrate waste) in this process --- it takes "about" 1 gallon of 70% nitric & 1 gallon of distilled water to dissolve a Kg of pins - that is (about) 2 gallons (or about 8 liters) of waste per Kg just to dissolve the pins - then you still need to wash the copper nitrate out of the gold foils - that is going to add another gallon (plus/minus) to your waste so "about" 3 gallons (11 - 12 liters) waste per Kg --- AND - you are talking about doing this on a scale of 10's of Kg's at a time - so we are talking about producing a HUGE amount of waste - on top of a "system" to deal with the NOx on a large scale
How do you intend to deal with this HUGE scale of (copper nitrate) waste :shock: :?: :?: :?:
I am not saying that you can't do it this way - I just don't think it is the best choice in setting up for working on the scale you are talking about --- in fact I think it is about the worst choice you can make for the scale you are talking about --- of course that is just my opinion
As Nick said
While working with cyanide can be dangerous so long as you understand it’s dangers it’s one of the best tools in recovery out there, I believe if done correctly it will be the best choice for this material
Per the underlined - I agree with Nick here & I will say it again --- "you really need to
look into cyanide leaching "
All the info you need to set up for cyanide leach is right here on the forum - I did a search using the simple word "cyanide" & got over 3,700 results
:arrow: http://goldrefiningforum.com/phpBB3/search.php?keywords=cyanide
Look for post by Deano, 4metals, GSP, Nick & Jon in particular & you will find all the info you need to set up &/or the info you need to ask questions &/or for advice
On the scale you are talking about - cyanide leaching would be my first choice
If I could not do cyanide leaching ( because I could not get the cyanide &/or regulations prevented me from setting up to do cyanide) my next choice would be to "
look into" melting the pins into anodes & then running them in a copper (refining) cell & then processing the anode slimes for the gold
For what it is worth - I spent a couple years doing some large batches of pins (30 - 50 pounds) with nitric
a little over a year ago I made a move from Wisconsin to Oregon - that resulted in shutting down my operation
The last year (before my move) I went to cyanide leaching
If I ever set up another operation - I will NEVER go back to using nitric - cyanide will be my first choice - or melting & running anodes in a copper cell as my second choice
IMO - other methods (nitric, Cu2Cl, sulfuric cell) may work fine on the hobby level - but on a "larger scale" - cyanide or electro refining cell are the better options
Kurt