AR very slow, precipitation non selective

[Anonymous]

Hello,

It is my first time trying to refine gold. I wonder where I have made mistakes:

I took 1 oz og 16kt gold that originated from one of mines in South America. I have flaked it by pouring into water. I have put it in 30 ml of nitiric acid (50% concentration) for 30 minutes (no visible reaction). Then I added 120 ml of muratic acid (20-25% concentration) and the soludion turned yellowish but and again no visible reaction happened, no fuming, nothing. I left it overnight and in the morning everything remaigned unchanged. Tested the solution with precious metal detection liquid from Shor and no gold in solution.

I have taken out the gold flakes and melted it with 3 oz of copper I took from a copper cable. I have put it in 100 ml nitic acid and strong brown fumes come out. I left it overnight. In the morning the flakes of gold/copper were still sitting in on the bottom but plenty of white-silverish spongy material was floating around. I have added 400 ml of muratic acid. Strong brown fuming was present. I left it overnight. In the morning the solution was dark green with gold/copper flakes still sitting in on the bottom and plenty of white-silverish spongy material floating. No fizzling, no fumes at this point. I have taken out the solution leaving the materials on the bottom. The solution I have treated with a pound of urea diluted in hot water but no strong fizzling was present. Then I have added 1 oz of Storm Precipitant from Shor diluted in 1 liter of hot tap water. Immediately green solution turned dark and WHITE mud started to percipitate to the bottom. No brown mud appeared. The white mud I rinsed then treated with agua amonia that turned dark blue and tried to melt with a torch but it appeared to be burning with very bright light so it wasn't any metal.

I turned back to the gold/copper flakes and material left behind when I taken out the AR solution. Again I put 100 ml nitric acid waited 30 minutes (brown fumes) aded 400 ml muratic waited for 2 hours until stopped fizzling and fuming. The flakes have are still sitting and white-silverish spongy material still there. Solution was dark green. Taken out the solution, added urea and Storm percipitant as before and this time brown mud dropped to the bottom. By the amount of the mud I know this is not just the gold. I was expecting around 20 grams of pure gold to collect and the mud is about 50 grams. I still have plenty of undissolved gold/copper flakes that were left behind when I have taken the AR solution out. The mud I have rinsed with water couple of times, and then with agua amonia. It never really turned very blue, maybe just a little first rinse with agua amonia, than rinsed with destiled water.

It appears to me that I have precipitated both gold and other metals with Storm precipitant from Shor. Can anybody tell me what I have done wrong. Please don't tell me to read all the forum because I have done that already.

The first question is why flakes solve in AR so slowly ? Why when I precipitate with Storm I am getting more mud that I expect ?

I think there is plenty of Silver and Platinum group metals in the gold I am trying to refine. Can anybody advise on a process that would really work in this case ?

I wound be VERY, VERY grateful if someone could help me solve this problem...

Regards,
Peter

 

[lazersteve]

Inquart (melt with 3x it's weight in silver then cornflake) a sample of the material and process with hot 35% nitric acid. What dissolves is the silver, what remains gets treated with AR for precious metals like gold and platinum.

You can see an inquarting video on my website.

[deleted error- thanks Jim]

Steve

 

[jimdoc]

Jim

 

[Anonymous]

Inquart (melt with 3x it's weight in silver then cornflake) a sample of the material and process with hot 35% nitric acid. What dissolves is the silver, what remains gets treated with AR for precious metals like gold and platinum.

You can see an inquarting video on my website.

[deleted error- thanks Jim]

Steve

How would I be able to precipitate silver from solution ? I think I have heard I can do it with table salt but more precise instruction I would highly apreciate.

Thank you
Peter

 

[goldsilverpro]

I'll try to wade through at least the first part of this. Here's what I think happened.

I took 1 oz og 16kt gold that originated from one of mines in South America. I have flaked it by pouring into water. I have put it in 30 ml of nitiric acid (50% concentration) for 30 minutes (no visible reaction). Then I added 120 ml of muratic acid (20-25% concentration) and the soludion turned yellowish but and again no visible reaction happened, no fuming, nothing. I left it overnight and in the morning everything remaigned unchanged. Tested the solution with precious metal detection liquid from Shor and no gold in solution.

It sounds like there is a very high silver content. The nitric alone won't attack the Ag or Cu, at all, because is is blocked by the high gold content. If the Ag is much higher than about 10%, dissolution of the gold by the aqua regia is blocked by the formation of a thin layer of silver chloride that forms on the surface. Therefore, nothing much will happen with either nitric or aqua regia.

I have taken out the gold flakes and melted it with 3 oz of copper I took from a copper cable. I have put it in 100 ml nitic acid and strong brown fumes come out. I left it overnight. In the morning the flakes of gold/copper were still sitting in on the bottom but plenty of white-silverish spongy material was floating around.

You did right to inquart, although silver is preferable to copper, since only 30% as much nitric is needed. I think your main problem was that you didn't use nearly enough nitric to leach out all the copper and silver. When all the nitric was used up, you still had a lot of undissolved copper remaining. The copper that remained cemented out the dissolved silver and this is the silverish spongy floating material.

Had you used enough nitric, all of the Cu, Ag, and Pd would have dissolved and you would have only Au/Pt sponge or powder remaining, of possibly 99% purity. After inquarting with the 3 oz of copper, you would have a total of about 104 grams of Cu and Ag in the alloy, including what was in the gold to start with. Since we don't know the Ag content, let's assume it's all Cu. It will take about 430 ml of 70% nitric, more or less, to dissolve 104 g of Cu. This is best done by diluting the 430 ml of 70% nitric with 430 ml of distilled water, for a total of 860 ml of 50/50 (35%) nitric.

I could go into much more detail, but this is the general idea.

After leaching out 100% of the Cu, Ag, etc. with nitric, it's a simple matter to collect the residue, dissolve it in aqua regia, and then precipitate the gold first and then the platinum. It's all on the forum, in great detail.

I won't comment on the use of the Shor pruducts, since I would never use them. If you have truly studied the material on the forum, you would know that there are cheaper and better alternatives.

I would suggest you read the Hoke book. It explains things better than I do.
http://goldrefiningforum.com/phpBB3/download/file.php?id=2480

Also, spend more time searching and reading on the forum. You really didn't spend that much time doing that, did you?

 

[nickvc]

Good advice from one of our leaders ,read Hoke , and the patience to try to explain what went wrong and why. I would add that after any dissolution done in nitric the solution should be set aside not used to make AR as this just adds contaminants back into what your trying to clean up causing problems at some stage. There really is no quick fix for refining keep it simple and follow well known and trusted methods , don't try new things until you really are competent and understand what's happening. For new members I would suggest Harold V s methods, they work if followed exactly every time.

 

[Oz]

I would add that after any dissolution done in nitric the solution should be set aside not used to make AR as this just adds contaminants back into what your trying to clean up causing problems at some stage.

It is worth noting that if there is silver present in your nitric and you add HCl to make it AR you will encapsulate some of your (gold and PGM) values within the silver chloride formed. It is a false economy trying to use the same nitric as it takes so little nitric to put reasonably clean gold into solution.

 

[4metals]

GSP is correct about the silver content of the gold. Years back I spent a considerable amount of time in Zaruma, Ecuador and the gold coming out of the mines there was 18% silver and 2% platinum.

Inquart with silver, digest in diluted nitric and process the insolubles in Aqua regia. After inquarting the high silver content will allow the platinum (if any was present) to be with the soluble portions. Cement on copper and it will all come down.

 

[Anonymous]

GSP is correct about the silver content of the gold. Years back I spent a considerable amount of time in Zaruma, Ecuador and the gold coming out of the mines there was 18% silver and 2% platinum.

Inquart with silver, digest in diluted nitric and process the insolubles in Aqua regia. After inquarting the high silver content will allow the platinum (if any was present) to be with the soluble portions. Cement on copper and it will all come down.

Finally after 4 treatements as I described above I manged to precipitate all expected gold (66% of the initial weight - before inquarting). Precipitation for Platinum produced dark powder that weights 3% of the initial material. I have a considerable amount of grey spongy material that solves colorless in agua amonia and turnes back to spongy material if table salt added so I believe it is silver cholride, but haven't yet managed to reduce to silver, so I don't know the weight of it.

What is left from Agua Regia treatement is a grey powder of a dry weight of 30% of the initial weight. I am confused because simple calculation shows that there is no room for silver weight, which I still don't know, but assume to be at least 10% of initial weight. Apparently some of the material unsolved by AR must come from the copper wire I have inquarted my gold with...

I attach a photo of the powder unsolved by AR. DOES ANYBODY HAVE ANY IDEA WHAT IT MIGHT BE ?

 

[Anonymous]

I would like to add that the powder does not solve in neither nitric acid nor Agua Regia.