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What was your source?
Was the solution heated during the AR step?
And again why Urea?
You had 111.64 what grams?? And a purity of 771?
How did you obtain these readings?
Have no experience with Hydrazine so no comment there.
Aluminum will drop everything , but if its left in solution it may turn into a difficult to filter gel.
Better use Copper, since it will drop PMs and Mercury only.
The gold can be many places.
As ultra fine particles in the filter cloth, as ultra fine particles in the liquids, and dissolved in liquids and particles inside the Silver Chloride.
Maybe some other too.
I'll wait for someone else to chime in too.
 
This is why people often copy and paste thread posts from new members, so it cannot be deleted.

Shame, the OP had contacted me with questions and he has a decent professionally made refining system and he is having problems. I suggested he post here because, although I can likely solve most of his issues, I feel it is better when the whole forum gets to see it and we get many varied answers. Then we sort through the responses and come up with a solution from a much broader base.

Maybe he had technical issues because when I suggested he post it in this section even I had troubles posting here, but Nugget fixed the issue and it was apparently fixed. Maybe (hopefully) he will try again.
 
4metals he was messaging me as well and I helped as much as I could and I pointed out that you will never get 100% return with wet refining in one process and highlighted where I would expect some possible areas of lose like melting area, filter and settling tank but without seeing the exact processes in operation I can’t think of any area to look at apart from those mentioned.
 
Nick,
From the photo's he shared with me of his system there are some pieces which inherently trap liquids. There is an in-line cartridge filter and they are very difficult to rinse free of any pregnant acid. The typical refining process always has small liquid losses and the best systems keep them to a minimum.
A few years back I made a spreadsheet to calculate the value of a single drop at today's prices. I was quite surprised to see that, for example, a single drop of pregnant acid which dissolved 14 karat gold at todays fix of $1,862, is worth $0.40 per drop. I remember when I first made the sheet I changed my ways of teaching stannous chloride testing. I used to cut filter paper into 1/2" wide strips and keep a beaker full of them near the hood. To test I would dip the end of the paper in the solution to let some acid absorb and test that with stannous. After knowing the drop value, I decided to see how much the paper absorbed. I pipetted 1ml onto a watch glass and soaked it with the paper and it easily absorbed it, and about as far up the paper as I would normally let the liquid rise. A milliliter is made of 20 drops as per the pharmacists of the world. That put the cost of a stannous test at 8 bucks!!!!!
I immediately began teaching clients to use a thin glass stir rod to retrieve a single drop for testing.
The reason for this long analogy is there are many drops that don't make it to the part of the process where the gold is dropped and we need to keep them to a minimum.
NOTE; We all know from experience that the test papers are saved for incineration and recovery so it is not lost, it just shows up down the line.
I hope the OP comes back here to post his process as there is much he can gain from this forum.
 
He also communicated with me, I also pointed out some places where the losses can appear. We interchanged few long messages. Original post, which is now apparently deleted, came from one of the replies he made, bit edited.

He described the process where he dissolved the feed in AR, then denoxed and diluted the solution to twice volume, filtered chilled solution and precipitated the gold with hydrazine. He has set up three precipitation tanks, and repeated precipitation once. And then cemented the rest of the solution on aluminium (or copper).

I pointed out that filtration could be part of the issue regarding statement "98% of the gold rest on the first filter, remaining 2% on the second filter". I recommended to leave the solution to settle for more than one day and observe sediment on the bottom.

Finally, he replied that he precipitated rest of the metals on aluminium. And he obtained violet sludge, which showed 30/1000 Au on XRF. In my opinion, some of the gold particles were so small they passed through the filter and didn´t settle well. Finally, after Al sludge came out of the solution, as HCl being spent, it locked the microparticles and allow them to be filtered.

But I assume this was only part of the issue. I do not obtained any pictures, but as 4metals said, every drop counts here. Final volume of his solution was 24 L after dilution. So 12 L of AR gold solution. So his roughly 12g loss in the process accounts for 60 mL of pregnant solution in all. Few mL there, testing, loss in filtration, incomplete sedimentation etc. and it will all came together :)
 
I always try to steer members who PM me about refining to post on the forum. A one off simple answer is different but in a case like this it can be an informative thread and many members can benefit. I don’t think it does the forum much good to have a private PM club as a lot of typing goes to benefit one individual. This forum was set up to be refiners helping refiners in a business where secrecy still reigns.
 
Years back I ran a refinery and we processed karat scrap (karat was king back then here in the US and I’m old) but we did 3 72 liter reactors of karat gold every day and produced over 100,000 oz a year as fine gold or about 3500 kg. All of the waste was passed through 3 connected gravity settling tanks and the retention time was maybe a week. Every year we drained the tanks and cleaned out the bottom and on average there was 3 kg of gold settled there. (Now before you get all excited it was $300 gold back then!).

So do the math. 3/3500 = 0.0000085%. That was what was lost as a percentage of the processing. Even when you filter well, something gets through. And even the filter papers which were collected and incinerated had gold trapped in them. Not as much as the tanks but the number escapes me.
 
I always try to steer members who PM me about refining to post on the forum. A one off simple answer is different but in a case like this it can be an informative thread and many members can benefit. I don’t think it does the forum much good to have a private PM club as a lot of typing goes to benefit one individual. This forum was set up to be refiners helping refiners in a business where secrecy still reigns.

I often pick up bits of information that has been or may be very useful from many threads that were beyond my understanding. Some threads gave me ideas that aided me in areas that had nothing to do with the basis of the original thread. Filtering, precipitation, melting are just a few. Just because some of the newer people aren’t involved in the conversation it does not mean we aren’t learning. The type threads 4metals is describing are often the best teaching aids in more ways than many realize.
 
Hmmm - OK - I got a couple PMs asking for help from Gold.refinery as well

I basically told him he would best served posting here on the open forum

Gold.refinery - you need to keep all your questions in one thread - also the replies you are getting from member are some of our very best & highly respected members - So you need to keep your questions focused (in one thread) so that we can give you better/focused answers --- instead of questions/answers scattered all over

Original post, which is now apparently deleted
Here is one of the PMs I got which was ether a copy of his (now deleted) OP in this thread &/or very close so I am going to post that here in the hope we can get him back on track - it's a long post

Kurt

------------------------------------

Hello

I set up a refining system, but I have little experience. To know if I was on the right track, I wanted to report one of Refine operations.
Please help me about losing gold in this operation.


We performed refining operation using the AR method. Our input was 2610 grams; Analysis includes: 765 gold, 68 silver, 148 copper, 8 zinc, 4 nickel, 6 cadmium and some others.

We calculated the acid values to digest 7.5 ounces per liter of solution. Hydrochloric acid 32%, 9.3 liters and 2.3 liters of nitric acid 64%. We flaked the gold as much as possible. Then we poured it in Tumblr.

We added 7 liters of hydrochloric acid along with 1.3 liter of nitric acid.

We also added some hydrogen peroxide during the slow reaction. After one hour, the reaction was somewhat balanced, we added 3.5 liters of hydrochloric acid again and slowly we added 1.1 liters of nitric acid.

After four hours, the reaction was very low. I added about one kilogram of 46% white urea to neutralize nitric. About Urea , I have little experience with urea. I added until the bubbles on the surface of the solution diminished. I added a little water. Then I did not see a quick reaction by adding urea.



After a while, I added 12 liters of 4 C cold water. We waited for a while, then filtered the solution, left the silver chloride, and transferred the solution with water until the transfer path became clear. At the end of the Tumbler wash we had 111.38 gr unresolved gold.

In the case of solid gold residue, I did not notice washing it with ammonia. Because they were not covered with anything. I first tested them with XRF and then melted them, their assay was 771 Au.


I Approximately 1.8 liters of 55% hydrazine is dissolved in 2.2 liters of water and Slowly add to solution in half an hour.

Add the flocculate , leave the solution for 12 hours.



The liquid became green and clear, we filtered the liquid into a secondary tank(with Fabric polypropylene), took all the pure gold. Then we washed the gold powder with hot water. Then we dried the gold powder in a steel container.

We filtered the solution with two polypropylene cloth filters. We did not use a paper filter, of course I like the paper filter because it does not absorb. We took more than 98% of the solid particles from the first fabric filter and the rest from the second filter. We thoroughly washed the filters. Some gold precipitated, we took it and sent the remaining liquid to the second tank.



Stannous test, when the gold was sitting on the bottom of the solution, I tested the solution on top of that gold. The answer was negative.

Unfortunately, after filtering the solution, I did not try again.

Also, all the water has been added to them while washing, now it may be close to 200 liters.

I added some aluminum to the solution and mixed it and let people do it.



I need to learn more about Stannous testing, it's very important. I have never had a positive Stannous test.



After melting and XRF test, the purity of gold was 999.6 Au and it was shown in the analysis 0.4 cu cu and no silver Ag. (But it seems not enough washing) because the surface of gold bullion was not best quality, Their surface is star-shaped impurities.



We dried the gold powder in a steel container, then melted it in an induction furnace with a new plant.



After accounting, we do not have 12.6 grams of gold. I'm surprised, all the steps went well, no errors, and I'm sure of the scrap analysis. There may be some during the initial dubbing and gold powder, but we were careful and definitely not a lot. We have two places still left, silver chloride, the second bunker deposit.



I added two sheets of aluminum to the second bunker.



Then we mixed well every few hours. We added flocculate and left for another day.



we filtered the place, the amount of jelly powder had accumulated on the bottom of the bunker.



We took it and heated it in a steel pan and it was almost dry.



We tested with XRF. Showed 30/1000 gold.


We transferred the rest of the solution to the third bunker and added the aluminum again.

So far, 12.6 grams of that lost gold, 3.6 grams in the second bunker have been deposited in the sludge, so our lost gold is about 9 grams.



How to get the gold in this purple powder?



My friend told me ,that powder put in reactor for next part refining. Is it ok?



So far there is some gold in silver chloride and maybe in the third bunker solution.



Dried silver chloride is about 170 grams, but I know the silver get is much less, right?

XRF testing of silver chloride showed that 98/1000 of it contained gold.



In the third bunker, after filtering, sludge containing 2/1000 gold was taken.(Almost very little)



Here I want the best way to recover the silver chloride to get the gold trapped in it and recover the silver.



Where do you think gold has gone?



This is important for any refiner.



It will not be economical to continue with these calculations.



Can you help find the deficit and control the various steps for possible corrections?
 
From the photo's he shared with me of his system
It would certainly good for any of us willing to help Gold.refinery to see those pics

Pics are often times more helpful then words alone

As a side note; - I may not be able to help much here as I am quite busy with other things right now - but - I see some of our very best are already trying to help here ;):p:cool:

Kurt
 
Kurt,

Since what he has posted already is now out on the forum I will make a separate thread this evening when I am at my laptop and post what you posted here as well as any photo’s I have. Then we can systematically start at the beginning and work through the process.
 
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