First time inquarting Karat gold

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resabed01,
The acid's when heated becomes stronger as gases are released in the aqua regia, and will normally dissolve much more metal into solution.

When I do the evaporation process after concentrating the solution down, I do not let solution cool to crystals, I will keep the solution heated as I add a little HCl, many times with this addition of HCl you will see some red fumes of NO2 gas, showing some nitric acid is formed with the HCl acid addition, with this small addition of hydrochloric acid, which is 32% HCl and 68% water, we concentrate the solution again, which drives off water vapor and then more nitric acid, with only a small amount of added HCl it does not take long to re-concentrate, before we make another addition of HCl and concentrate the third time to try and remove the last traces of nitric from the solution of gold chloride. the goal is to concentrate but not form crystals.

Did you eliminate all of the nitric when you evaporated your solution down and let it cool to crystals, I do not know, but I would not be surprised if you may not have, as salts of metals, like copper for instance can be evaporated down forming a crystal of copper nitrate, if we added an acid (hydrogen) to the nitrate salts we would reform nitric acid in the solution of copper nitrate, with this in mind, then I think it is possible to crystallize a solution containing nitrates, whether your crystals of gold chlorides have any remaining nitrate salts that could reform nitric in solution, I do not know.
 
Butcher, I get what your saying. I'm new to AR so still learning this. I'll re-heat the crystals back to solution and try the small additions of Hcl like you suggested.
I don't want to be adding SMB to drop gold until I'm sure it's properly denoxxed.

I'm surprised it took so little nitric acid in the AR to dissolve about 25g of gold.

Thanks for your help.
 
I would add a little HCl to bring the salts back into solution with some heat, and then proceed with the second evaporation, heating before adding acid you could vapor off a little of the value, a few drops of sulfuric acid is also helpful to keep the gold from forming salts as you evaporate.

Another option if you brought these salts back into solution you could add a little sulfamic acid to rid any remaining nitric (which also will form a little sulfuric in solution).
 
I heated the salts back to solution and added a small amount of HCL. There were no red fumes emitted. Went through a second evaporation just to be sure. Moving on to dropping gold I added another 50ml or so of HCL and brought the volume up to 600ml with water. A cloudy precipate formed which slowly settled after which I filtered twice.

I weighed out 26g of powdered SMB and mixed it with a small amount of water, just enough to dissolve the salt. That I added to gold chloride solution and mixed in.

At first (about 2 seconds) nothing happened. Then it suddenly erupted with gas and instantly changed the solution from bright orange to a dark muddy brown, almost black. It happened so fast, like someone flipped a switch. Never seen gold drop so fast as I'm used to dropping gold from HCL/bleach solutions. I wish I could have caught the reaction on video. Good thing I had it in a large enough vessel or I could have lost considerable values when it erupted.

After about an hour it was mostly settled. The solution turned clear but there was a small amount of very fine gold still settling so I let it sit overnight. I tested with stannous after the drop but I think I was getting a bit of false positive. I'll test it again tonight.
 
resabed01 said:
I heated the salts back to solution and added a small amount of HCL. There were no red fumes emitted. Went through a second evaporation just to be sure. Moving on to dropping gold I added another 50ml or so of HCL and brought the volume up to 600ml with water. A cloudy precipate formed which slowly settled after which I filtered twice.

I weighed out 26g of powdered SMB and mixed it with a small amount of water, just enough to dissolve the salt. That I added to gold chloride solution and mixed in.

At first (about 2 seconds) nothing happened. Then it suddenly erupted with gas and instantly changed the solution from bright orange to a dark muddy brown, almost black. It happened so fast, like someone flipped a switch. Never seen gold drop so fast as I'm used to dropping gold from HCL/bleach solutions. I wish I could have caught the reaction on video. Good thing I had it in a large enough vessel or I could have lost considerable values when it erupted.

After about an hour it was mostly settled. The solution turned clear but there was a small amount of very fine gold still settling so I let it sit overnight. I tested with stannous after the drop but I think I was getting a bit of false positive. I'll test it again tonight.
Click to expand...

I've only ever used HCL/bleach to dissolve gold and when I add my SMB, I don't get any eruptions (unless i've just heated it and there is lots of chlorine on the top), but usually after 2-3 seconds I do get the immediate color change to brown. Was it the eruption that was different or the color change then what you are used to?
 
I've had drops where I'd add the SMB and it would fizz a bit then the color would slowly shift to a muddy brown. Sometimes the reaction would take some time to complete like several minutes. Then usually I'd have to wait a day for it to settle. But this one was quite fast and violent. I'm guessing my gold solution was too concentrated, I had about 25g of gold in a 600ml solution. That and maybe I mixed in the SMB too fast.
 
Was you stirring while you was adding the smb at the same time or was you just adding it and then stirring?
 
Palladium said:
Was you stirring while you was adding the smb at the same time or was you just adding it and then stirring?
Click to expand...


I think I was stirring it or had just stirred it so it was still in motion when I added the SMB. Also, I was working out in the heat of the sun, the solution was warmed by that somewhat.
 
Well, I've been itching to see a button out of all this for far too long. Managed to get the washes done and fired up the torch tonight.




I was waiting for it to cool enough so I could pluck it out of the dish and I watched as the entire top of the button caved in.
Thanks for all your help guys, inquarting and working with AR was all new ground for me.... I appreciate your help

Also, hats off to you guys that do this on a regular basis and can complete a lot in a day or two. There's lots of steps from start to finish, I don't know how you do it in so little time :shock:
 

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