# Precipitating gold problems



## Jeff (Feb 12, 2013)

Greetings everyone. I've been trying to precipitate gold out of aqua regia for several weeks now. I've tried just about everything. After I dissolve some gold plated pins in aqua regia, then kill the nitric acid with urea, the next step should be adding a precipitant of which I've been using sodium metabisulfite. It doesn't work for me for some reason, no matter how much smb is added. The aqua changes from dark green to brown when the smb is added. I get a small amount of precipitant after letting it sit even over night, but not very much at all. Testing it with stanous chloride, it shows a lot of gold still in the aqua solution. I've tried heating it, cooling it, you name it and it just won't drop the gold. I've tried several different smb suppliers also, even stump out. So the smb is what it's suppose to be. I called the maker of stump out, and they told me it is definately sodium metabisulfite 98%. I am using reagent grade nitric acid, 75% or something like that and regular pool muratic acid. Can anyone tell me what is possibly going wrong? I also just ordered some Subzero and Storm precipitant from Shor to give it a try. Does anyone know what chemical the Storm precipitant is ?


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## philddreamer (Feb 12, 2013)

How many pounds of pins did you processed? How much Hcl and nitric did you used? You might just have excess nitric in your solution. Maybe you still need to add more urea in order to neutralize the nitric, or just heat the solution until you get rid of the extra nitric. AR is not the best process for recovering gold from pins; the proper way of processing pins has been discussed many times; you need to do a search and some reading.

In my opinion, you're wasting money buying those chemicals from shor! You already have them! Storm prep is SMB...
Take care!
Phil


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## tek4g63 (Feb 12, 2013)

Storm is SMB just renamed and the price is higher.

What color stain do you get when you test with SC? Because the over use of SMB can give a false positive, brown to blackish stain, gold would be purple black. 

Download the free copy of Hoke's hook and give it a read. ( you will find a link to it in the books section ). You made many mistakes here. For example, AR is not a good way to recover gold from plated material, urea is not good for ridding your solution of nitric, and many more....

Cap your solution and put it away for a while. When you have studied more your gold will still be waiting for you.

Good luck, I hope it turns out well.


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## FrugalRefiner (Feb 12, 2013)

Jeff,

Welcome to the forum. There is a lot to learn if you want to recover and refine precious metals, but you've found the right place to do it.

The first rule is to be safe in everything you do. Before you jump into any of the processes you see discussed here, be sure you understand the potential hazards and do everything you can to minimize the risks. Read EVERYTHING in the Safety section of the forum, especially the Dealing with Waste topic. No amount of precious metal is worth jeopardizing your health or the health of those around you. 

I strongly encourage all new members to follow the Guided Tour created by LazerSteve. It will provide an introduction to the forum and numerous valuable links including the General Reactions List. Be sure to follow the link to his web site as he has many outstanding videos, a collection of great reference documents, and he sells a lot of the supplies needed to get started including detailed instructional DVDs. Samuel-a also has a lot of videos, guides and tutorials at his web site Gold-N-Scrap.

Download C.M. Hoke's book Refining Precious Metal Wastes. You'll see her book mentioned repeatedly here on the forum for good reason. It is probably the best book ever written for the beginner who wants to learn refining. It is written in layman's terms and will provide a solid foundation that will help you understand everything you read here on the forum. You'll also find a tremendous amount of information in the two Forum Handbooks compiled by aflacglobal, Forum Handbook Vol 1 and Forum Handbook Vol 2.

Good luck on your adventure.

Dave


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## mls26cwru (Feb 12, 2013)

how much material did you start with? from what i gather reading other posts, pins are notoriously low yielding items... you may not have that much gold to drop if you didn't start off with a large enough quantity. just a thought...


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## Jeff (Feb 12, 2013)

philddreamer 

Thanks for the reply. I've been doing small batchs so I don't waste it. To start, I put a couple ounces of the pins with only muratic, aprox 100ml, then added small amounts of nitric until they were completely stripped. Then I gently heated it to drive off the nitric. After it cooled I added urea until there was no more reaction, then added the smb. I added probably a couple ounces of urea, and about the same smb. I did several different batchs with each having more or less urea and smb. It didn't seem to make any difference that I could see of how much urea or smb was added. I also did a few batchs heating it until there was absolutely no nitric and only added the smb. So I've tried many different combinations, everything I could think of. The stanous chloride tests show the q-tip turning dark dark brown to black on every test. It's pretty much got me stooped. I do have a couple yrs of college chemistry but it was back in the late 70's. So I'm really rusty at chemistry but I am aware of the safety and basics when working with acids. I do hard chrome plating once in a while and have a lot of glassware and chemicals from all the years. Long story, but I do have a rusty background in chemistry. This is the first time I've attempted recovering gold from anything. A couple yrs ago I bought a few huge IC emulator machines that were stuffed with thousands of gold plated pins for wire wrap. Just one I pulled about 10 lbs of the pins so I decided to try recovering the gold. Here I am now


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## glondor (Feb 12, 2013)

Yield on a couple of ounces of pins would be hard to see. If there is any dark powder on the bottom of your beaker, that is your gold. From an ounce or two it would be a small fraction of a gram. Hard to see in other words.


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## Palladium (Feb 13, 2013)

You say stripped. Did you dissolve all the materials or just the plating?


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## jonn (Feb 14, 2013)

Hey Jeff, welcome to the forum. If you insist on using nitric and hcl, Ar, try dissolving the pins in nitric first. No hcl. You can remove the base metal and see what's left. Surely not enough from 2 ounces of pins to be noticeable. Once all the base metal is dissolved, let settle. Once settled you decant or siphon the liquid leaving gold flakes behind. Pour some clean water on those flakes and let settle again, decant. Move these foils to a small storage beaker. If you want to know the weight of these you can wash well and dry, put these foils on an accurate scale. I doubt your scale will even move any more than 0.1 gram. You could of course accumulate the foils by repeating the process multiple times with more pins. Add all your foils together and then proceed to AR, aqua regia. You will have much better success. Your nitric solution will contain all the base metal, copper, when you learn how to process that solution you can recover your copper and also reuse that solution to refine silver. Remember, always eliminate your base metal, or separate it from the gold first. Good luck. Have your read Hoke?


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