Unable to recover Gold from cyanide solution, Please advice!!

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ChienBui

Member
Joined
Mar 28, 2020
Messages
5
Hello everyone, I am a new member, but not new to this forum. I've this problem for quite sometime and have been searching for answers here and everywhere else but to no avail, thus I decided to post a new topic. I apologise before hand for my bad English.
I am manufacturing 24k hard gold and doing refinery of 24K gold for my market. The 24k hard gold first required to have potassium gold cyanide (PGC), that I also have to make rather than buying from the market. The liquor in hard gold production tank I have to buy from supplier, and what in there is a secret to me of course. Now the production process is to put the PGC in the liquor tank and run electrolysis. Initially I need minimum of 1.47kg PGC in the tank (1kg of 24k Gold), and I always keep that amount in there. My tank had become quite dark (reason will be posted below) and I have to make a new tank, thus the need to recover the gold. I poured all the liquor into the electrowining machine, but so far I've only able to collect 318g of 9999 Gold ( after AR refinery). I have put some more Potassium cyanide in the electrowining tank and keep running, but I didnt see any gold on the cathode, only some black powder on there. I have no idea what is that black powder. There was some black powder in my first attempt along with gold, after drying those I have 420g of gold and powder, then after AR refinery only 318g of pure gold collected as mentioned above. Now I have 40L of liquor and more than 600g of gold in solution that is unable to electrowin out.
The liquor was very clear when I first started, The few first batch of PGC were a bit yelow in color, but no effect on the production. Later when I made the PGC, the solution got "burn", my PGC is half black, but I still put it in the production tank. That happened a few times until I got it right, the PGC now is white as salt, but the production liquor had become really dark, and thats why I have to make a new tank.
How do i recover the gold out of the old liquor?
What is that black powder that I recover up until now? Given that I had only used distilled water, 24k Gold and Potassium Cyanide to make the PGC. That black powder can not be dissolve in nitric acid, not even in AR as I tried, because my first thought was it must be some kind of metal as it was the result of electrowining.
Thanks in advance!
 
Welcome to the forum.
As you say you keep the amount of gold in your tank level you must have assay capabilities, my advice is to assay your solution to see if it has gold still in there, if not then either you have a theft problem , from what I understand you are plating items, or you are plating too much gold onto the items.
If I didn’t understand your problem properly please give further details so that I or others can help.
 
nickvc said:
Welcome to the forum.
As you say you keep the amount of gold in your tank level you must have assay capabilities, my advice is to assay your solution to see if it has gold still in there, if not then either you have a theft problem , from what I understand you are plating items, or you are plating too much gold onto the items.
If I didn’t understand your problem properly please give further details so that I or others can help.
As I manufacture 24k hard gold, whatever quantity of gold I took out, I have to put equavalent amount of PGC back in, so the amount is more or less always at 1kg gold in the tank. Theft is unlikely the problem as every steps was done by myself.
 
If you put aluminum foil into the solution it should change color towards brown if there is none then it will just go lighter in color.
Are you plating items ? Or are you doing something else ?
 
nickvc said:
If you put aluminum foil into the solution it should change color towards brown if there is none then it will just go lighter in color.
Are you plating items ? Or are you doing something else ?

I'd say its similar to plating, but these products mold will go through acid to dissolve the base metal, which is copper mold, leaving pure 24k hollow gold products.
So the Al fold reaction is the same as zinc foil? I tested with zinc foil before, it turned light brown. But now zinc foil does not change at all
 
You will be using jigs then to hold your items so some gold will be on them, also you rinse the products so again some gold will be in your rinse water.
If the gold you expect to be there isn’t and there is no chance of theft then there must be another reason some of which I posted above but without knowing exactly what you are doing through all your processes you are going to have to play at detective to find the answer. It sounds as if you have no gold or very very little left in the solution so look at all your processes and check any maths to see if the answer is under your nose.
 
I appreciate your input, but frankly I know what I am doing in management. The Liquor had been assayed and gold is definitely in there, my problem remains the same. I really need to know how to get the gold out of the liquor, as zinc cementation and electrowining all failed
 
I didn’t mean to make you feel like you didn’t know what you are doing but sometimes we all miss the obvious. When you ran the solution through the electrowinning you may have killed the cyanide try adding some into a small test solution and then add some zinc or test with aluminum foil to see if you get any deposit, lye should also help you to cement the gold as it will dissolve the zinc and cement the gold from the solution, don’t add too much, it’s also worth heating your solution before trying the zinc.
 
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