# Why Dissolve the Gold?



## arthurcorbit (May 9, 2008)

I have wasted a lot of gold trying to dissolve it and then drop it out. Mostly it was with AR, SSN or Halox leaches. I finally decided I was going to find a better way to get my computer gold. About a week ago I took some pins and covered them with full strength Nitric Acid. In less than 10 minutes all the junk metals were completely dissolved and my gold was laying in the bottom of the jar looking good.

I sucked the gold out and washed it good and dried it. Now it is ready to do what ever I want to with it and I didn't loose one speck of it. I had one big problem with this. That's getting the Nitric to do it with. The nearest place where I can b uy Nitric is 300 miles round trip so I started looking for waya to make my own Nitric Acid.

I bought 1.5 gallons of Sulfuric Acid at my local auto parts store for a little over $10. I then bought 8 lbs of Nitrate of Soda for a little over $10. A lot of the formulas I had seen said to boil the Sulfuric Acid and a bunch of junk like that. 

I had tried to dissolve Nitrate of Soda before and in a cold liquid it is really hard to do. I set up my little crock pot and put about 2 inches of hot water in it. I had a glass quart jar about half full of the cold Sulfuric Acid. I let it warm a while. It was just good and warm and wasn't even close to boiling. 

I started stirring the Nitrate of Soda into the acid. It dissolved pretty slow but it would dissolve at least. I kept stirring it in untill it was saturates and wouldn't dissolve any more. I then took the jar of home made Nitric out of the crock pot and set a Pint glass jar in it that had some chipped up phone boards in it. I had removed all the green solder mask from the boards with a strong lye water.

I covered the boards with the home made Nitric. There was no boiling and only a small bubble now and then. As it warmed up a little it started to bubble a little more but there was still very little chemical reaction. I really didn't think it was going to work but I let it set and came back in about 30 minutes. All the junk metals were dissolved and the gold was completely loose from the boards. The next day I tried it cold and it worked jjust as good and just as quick. 

Art


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## lazersteve (May 9, 2008)

Art,

The reason you should dissolve your gold foils after you recover them is to remove any final traces of contamination from it. If you melt the foils directly out of the nitric mix, you will end up with impure gold. There are no shortcuts to fine gold. Dissolve the foils in HCl-Cl, filter until clear, and precipitate with SMB.

On a side note, you mentioned you bought the sulfuric acid from an auto parts store, but you didn't mention concentrating the sulfuric acid. The best nitric acid is made by using concentrated sulfuric acid and a minimal amount of water. The auto parts store battery acid is only 35% acid and 65% water. 

I've worked out a new nitric formula for using the 35% sulfuric without boiling it down. I still have to test the reaction, but I'll post it once I've tested.

Steve


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## Harold_V (May 10, 2008)

Nope! A guy that melts foils is no better off than a guy that dissolves everything in AR, expecting to recover pure gold. It ain't gonna happen!

As Steve suggested, it is a *requirement* that the gold be dissolved and filtered once separated from base metal. In spite of your very best efforts, you'll come to realize that there will still be ample base metals present, often those that harm the quality of gold. Even after dissolving, filtering and precipitating, gold is still not pure and requires a rigid washing procedure to remove base metal traces that are dragged down by the precipitated gold. 

There is no better time to dissolve gold than when it's finely divided, as it is after extracting from plated materials using either a stripping cell or one of the other processes for eliminating base metals. The gold dissolves almost instantly, and completely. Filtration and the addition of a trace of sulfuric acid allow for eliminating the vast majority of contaminants that will have escaped you in pre-processing, then the use of a selective precipitant will eliminate others that are in solution. The only problem you'll have then is drag-down, which is an ongoing problem, thus the need to eliminate as much of the base metal that is possible. 

Having stated the above, understand that I'm approaching this from the standpoint of pure gold. If your objective is to simply recover gold, with no regard to its purity, melting those foils directly, with no further processing, is certainly adequate. For the record, I wouldn't do it, not for any reason. 

You mentioned having lost gold in processing. Unless you've discarded filters and solutions, the gold is not lost, it's simply in a form that you may not identify. Make mention of what you have, and how you're treated the material, and I'll make some recommendations on recovering the values. 

Harold


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## arthurcorbit (May 10, 2008)

Evening Steve,

First I want to thank you for all the information you have posted on your web site. Those videos are really helpfull. I sure hope you continue to add more information. Especially on your method of getting the gold to the point where you dissolve it. Nitric is the only thing I have found that will do this.

I'm not planning on refining the gold I recover at this time. I am just keeping it in the foil state and sticking it back where it's safe. I probably will at some point but not now.

I'm looking forward to your new formuls on the cold Sulfuric. I just don't enjoy boiling acids of any kind. I found out something the other day about making the Nitric. It doesn't need to be very strong to dissolve the junk metals and free the foils. I just warmed the sulfuric in a crock pot of warm water and then saturated it with the Nitrate of Soda and it was plenty strong for what I use it for. 

I had some telephone boards that the traces and all were gold plated so I removed all the solder mask with strong lye water so the Nitric could get to the traces. About 30 minutes is all it took to free the gold. I don't plan on mixing any more AR or SSN so I really don't need the strong Nitric.

Thanks to your videos when I do get ready to dissolve my gold I'll sure as heck know how.

Art


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## arthurcorbit (May 10, 2008)

Evening to you too Harold,

Yes I understand about all the junk that can be in the recovered gold. I usually put my recovered gold back in fresh Nitric and leave it there a few hours. That usually cleanes it up pretty good.

You mentioned the methods to strip the gold. That's what I am trying to come up with now and the Nitric is the best I have found so far. I know there are better ways but I don't happen to know what they are. I have probably learned more on Steve's web site the past few days than I have in the past 20 years With this trial and ewrror I have been doing. I thank you very much for your input.

Art


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## goldsilverpro (May 10, 2008)

Very little of the gold plating is pure. Alloying ingredients, such as nickel, cobalt, or indium, are intentionally added to increase the hardness and wearability. The purity of most gold plating ranges from 99.0% to 99.9%. When you leach the foils with nitric, you are only removing the plating layers under the gold. You could leach for 100 years and still not remove these alloying metals. In other words, you'll never purify the foils by simply leaching them in nitric. You'll have to eventually dissolve and refine them. 

About the only time pure gold plating (9999) is used is on components that must subsequently be heated to melt brazes for such operations as lid or die (chip) attachment. Less pure gold would discolor when heated.


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## arthurcorbit (May 10, 2008)

Good Morning GoldSilverPro,

I'm not trying to refine the gold with the nitric. All I'm using it for is to separate the gold from the other metals it is plated on. I think my question "Why dissolve the gold" was missunderstood. I meant in the process of removing the gold from what ever it is plated to.

In the past I have tried to dissolve the gold off the copper and I would wind up with so much other junk in the leach I couldn't drop the gold. I know people that are still trying to do it. All I have ever used is the AR, SSN and Halox Leaches. I didn't know about the HCL and bleach or the HCL and peroxide untill someone seen it on Steve's web site and was telling us about it on another Yahoo Group. I also didn't know about the Sodium Metabisulfite.

Those two leaches and the SMB will make a big difference in my gold operation and I thank Steve very much for the information. I also thank you and some others for the information you post on this forum. At this point I'm not in the gtold recovery stage. Instead I am in the learning how to recover gold stage. Most of what I have done so far has been gtrial and error testing of different methods. No doubt you know how hard it can be to come up with good information on any subject on the net.

Art


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## Harold_V (May 10, 2008)

arthurcorbit said:


> No doubt you know how hard it can be to come up with good information on any subject on the net.
> Art



You can avoid the vast majority of the moronic notions you find on the net by following my advice. 

Get Hoke's book and read it until you understand what it says. The informaton contained within is timeless, and provides a basic understanding of refining. *No one *that refines should be without a copy. 

Harold


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## arthurcorbit (May 10, 2008)

Thanks Howard,

I'll see if I can locate a copy. I don't plan on doing that much refining right now but that could change and I would want to do it right. A man that really intends to do something can't have too much good information on the subject. Thanks for the tip.

Art


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## arthurcorbit (May 13, 2008)

Another good day gold mining. I made up a couple of batches of the home made Nitric this morning. It was only about 3/4 of a quart at a time. I poured about 3/4 of a quart of the cold sulfuric acid in a quart fruit jar and added 5 table spoons of the Nitrate of Soda. This was just a stainless Steel spoon, not a measuring spoon.

I poured boiling hot water in my little crock pot and set the Nitric in the hot water. All the Nitrate of Soda dissolved in about 15 minutes. I has several gold plated cable fittings Paul sent me. They were about 1/4" fittings and plated real heavy. As soon as the Nitrate disasolved I covered the fittings in the nitric. It started working real good in just a few minutes. There was plenty of chemical reaction to keep it good and hot and working. It took about 2 hours to completely strip the fittings. I poured off the copper loaded Nitric about 4 times and diluted it and filtered the gold out of it. It took a while but I finally wound up with 3 to 4 grams of nice gold foil.

I think it would be safe for me to say the home made Nitric will do everything I want it to. It's no problem to make it just as strong as the 35% stuff you buy. Just heat the sulfuric and dissolve more of the Nitrate into it.

Art


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## flankdrive04 (Jun 11, 2008)

goldsilverpro said:


> Very little of the gold plating is pure. Alloying ingredients, such as nickel, cobalt, or indium, are intentionally added to increase the hardness and wearability. The purity of most gold plating ranges from 99.0% to 99.9%. When you leach the foils with nitric, you are only removing the plating layers under the gold. You could leach for 100 years and still not remove these alloying metals. In other words, you'll never purify the foils by simply leaching them in nitric. You'll have to eventually dissolve and refine them.
> 
> About the only time pure gold plating (9999) is used is on components that must subsequently be heated to melt brazes for such operations as lid or die (chip) attachment. Less pure gold would discolor when heated.



Would I be right in assuming that as a first step, you could do the nitric thing, and as your qty builds up then dissolve filter etc?

I would preffer to have the gold stored for later dissolving, to give me time to acumulate enough....Just a thought!


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## OMG (Jun 11, 2008)

Thats what I'd do if I were refining scrap plating. Use the easy cheapo method on the pounds of scrap getting say 90% pure gold. Then when I had a couple kilos 8), i'd go into the whole drawn out process of getting it up to 999 or whatever. Makes complete sense to me.


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