Starting Over... Slowly

[Palladium]

Hoke says 1lb (453.59 g) per 50 penny weight of gold.
50 penny= 2.74 oz
2.74 oz = 86.31 g
453.59/86.31= 5.25 g copperas per gram of gold.

You had 1/4 oz of gold= 7.875 g
7.875 X 5.25= 41.3 g copperas needed

Did you add the whole copperas you mixed (113.4 g ) to your solution? That's almost 3 times what you need.

 

[megaplow]

Thanks for catching that. I forgot, I didn't add the full amount.
I only added about 1/3rd. As I was pouring and never saw a cloud form I assumed I was doing something wrong. Thats when I pulled a little aside and did a test.My test even with too much copperas never formed a cloud.

Joe

 

[megaplow]

One more problem with my current solution. I believe I should have used 100ml of HCL. I wound up using 8oz. Since I used too much HCL and CL will I see issues from that?

Joe

 

[Palladium]

You can over shoot the hcl and it shouldn't cause problems. It's the oxidizers that cause problems with your solutions (nitric, cl, H2O2 ). These will also cause problems with you reading your stannous test for gold in solution. Cl and H2O2 is faily easy to break down with heat where as nitric is not. You may still have some free cl in your solution is why it won't drop. When this happens to me i cover the beaker with a watch glass so nothing can escape but the gas and i put it on a slow boil for about an hour to remove the free Cl. This is different from evaporation where you don't boil. Then i sit it to the side for about an hour or two to cool and then try your drop again.

 

[megaplow]

Previously when I was using HCL + Nitric acid, I used the non boil method to get rid of the nitric acid. This time I will boil the solution in order to remove the cl. Is there any way I can tell how long to boil it or when the cl is gone? I am relieved that there is still hope for this batch.

 

[Palladium]

I didn't say their was hope. Well i guess their is always hope. lol
If nothing else you can use a piece of copper wire and make a recovery effort so all is not lost. Cl and H2O2 beak down with heat pretty fast when the temp of the solution rises. The hotter the solution the less it will hold when it comes to a gas. Different gas will have different percentages of gas it will hold per volume of solution. Cl will gas off pretty quick when the temperature rises so about an hour should do the volume you have, probably less but i say an hour for good measure. When i said boil earlier i meat just the point where you see bubbles starting to form and hold it right about there. Not a roaring boil!

 

[butcher]

megaplow,
I believe your still on track, and Palladium, is giving good advice keep following his advice, I just thought I may add something to consider, your solution looked good in the picture above, this sounds like a minor problem, that you can overcome easily, I would give it a good heating, cover and let it sit overnight, check it next day to see if you have a brown powder in the bottom, take a sample of solution and test with stannous chloride, also take a sample in a white spoon or spot plate add a few crystals of the ferrous sulfate (copperas), if violet in stannous chloride test, or brown precipitate in spot plate you will know what to do next.

Those copperas crystals in the link you posted look good, keep them from air.

 

[megaplow]

Hold the press! I think I got it!

A little background. Previously I mentioned that I added copperas and nothing happened. I measured out .2oz instead of 2oz of copperas. Regardless of what I added, the cl left in the solution was causing problems. Once I added the copperas, the solution was no longer testing positive for gold. After a good simmer, the solution once again tested positive. This is also the 1st time I have heated any of my solutions. I was trying to avoid it, but its a necessary process.

Last night I made up a new batch of copperas and added it to my solution. You can see the video here.
http://youtu.be/LkLRpigA5EI

Today I woke up to find this:

Tonight I will test the solution to see if there is still more gold in it. Then add enough copperas to drop that. Then hopefully be rinsing and making a tiny tiny button.

Thank you all for your help, you guys are amazing!
One thing I would like to change next time would be to use H2O2 instead of CL. I feel its less toxic. I am ready to process the rest of my boards using my current technique. Nitric acid to remove base metals, then HCL and H2O2 to dissolve the gold, then copperas to get it back.

I really wish I knew all this before my 1st batch,
Joe

 

[Palladium]

Glad you got it joe!
Now if you can help me figure out this Adobe thing out we will both be happy. :twisted:

[youtube]http://www.youtube.com/watch?v=zu2XA7u4WTg&feature=relmfu[/youtube]

 

[megaplow]

Oh man... (facepalm)

 

[Palladium]

Oh man... (facepalm)

I think your pretty cool Joe. Keep up the good work.

 

[goldenchild]

Oh man... (facepalm)

So you're the one making the endless stream of updates! :lol: Joe, do you do any work on dreamweaver? That's our primary ide at my job using ColdFusion. Nice to see another tinkerer on the forum. Admittedly a much more sophisticated tinkerer.

 

[megaplow]

Two steps forward and...
Since I was seeing some success, I started another small batch. The boards were mostly stripped and there was a good collection of flakes on the bottom. There was still a lot of gold left on several of the boards. I figured I would try heating the solution in an effort to make the acid more agressive. The previously attached gold was free, but now all my flakes have disappeared. I was under the impression that nitric acid alone couldn't dissolve gold. I am assuming my solution is now base metals and gold.

Joe

 

[butcher]

It may just show up as brown powder, (you may have had some chloride contamination somewhere like water, dirty vessels?), just keep adding copper to the solution until no more copper reacts even with heat, any gold would be pushed out of solution.

If you have any tin you will also form gold colloids, circuit boards have solder, the tin and gold my be in the filter later as gold colloids and tin gelatin, incineration of the filters and a boiling wash in HCl, and hot water rinses, you can get the gold back, a big pain in the back side, keeping tin out of nitric to begin with is really the key.

I would choose acid peroxide to remove copper and foils from the boards, (removing as much solder before hand with HCl), the copper II chloride leach is much cheaper than nitric for me, and although a challenge (tin still big trouble),it seems somewhat easier to deal with in concentrated HCl solutions.

Tin as far as I am concerned is a collector of fine gold (forming colloids), so anytime I have tin and dissolved gold or gold powders, the filtered material is reprocessed for values.

Keeping tin out of solution should be the goal; it just makes things so much simpler.

 

[megaplow]

Very insightful,
The boards I am using are clean and have no components on them. Thus no solder. My through holes and all mounting points are gold. After some time in heated acid, the green portion of the board separated exposing the fiberglass and whole underside. I assume this is where the tin may have entered the mix. There is an orangish gell on everything now. I guess thats my tin colloid. I will push out the tin with copper and see how that goes. For my next small batch I will be using hcl /peroxide to dissolve my gold. What is the nitric acid substitute for getting rid of base metals?

Take care,
Joe

 

[Harold_V]

Previously when I was using HCL + Nitric acid, I used the non boil method to get rid of the nitric acid. This time I will boil the solution in order to remove the cl. Is there any way I can tell how long to boil it or when the cl is gone? I am relieved that there is still hope for this batch.

I would caution you against boiling so long as you have gold in solution. There's no real benefit in doing so, in that heating to near boiling will rapidly expel chlorine without risk of losing any values. In any case, make sure you have a watch glass covering the vessel, to prevent contamination, as well as to capture any traces of values that may be expelled by over heating (boiling).

Harold

 

[butcher]

"I will push out the tin with copper and see how that goes."

Copper would not cement tin; tin is higher in the reactivity series of metals than copper.
Filtering may capture most of the tin (it forms a gelatinous substance that clogs filter pores), but if much tin that may prove difficult, (Charmin-plug or fiberglass plugged funnel can help some), if tin content is high, if tin content is extremely high the only solution at times is to completely evaporate solution, dry powders and incinerate, and wash tin oxide in boiling HCl, (that does not sound like the case here).

"For my next small batch I will be using HCl /peroxide to dissolve my gold."

HCl with small addition of 3% H2O2 peroxide will dissolve copper not gold;
This copper II chloride leach is reusable.
HCl and strong peroxide would dissolve gold, but this should only be used after base metals are removed, and here I would use the HCl and bleach method normally, if dissolving gold was my intent.

"What is the nitric acid substitute for getting rid of base metals?"

Copper II chloride leach also called Acid peroxide, or (AP leach), if I understand the question I think you are asking.

 

[megaplow]

In my 1st batch I wound up with a solution containing all metals, base and valuable. That batch is still in the corner waiting for my return. I dont feel ready for a relationship with her yet, so she is going to have to wait. In the mean time I have had some success with smaller batches and different acids. Things were going swimmingly until I added heat to nitric acid and wound up with an overly dissolved solution again.

Moving forward I am looking for a solution that will dissolve base metals without dissolving gold. Sounds like AP leach is going to be my new tool for doing that. I like that it is reusable too. What scares me is that if I get the mix wrong I will dissolve the gold too. The nitric acid doesn't make me all that comfortable, so any substitute for that is welcome. It was the 1st time I had to pay a hazardous shipping fee.

My last success with dissolving gold (post base metal removal) was with HCL and bleach. The fumes were super strong (I was wearing a respirator, but the back yard - from the vent - smelled) so I was thinking AP leach would be better. After all the advise, I think AP leach for base metals and HCL and bleach will be the combo moving forward.

Now for my current mess. I have taken the copper sheets out. I have about 800ml of solution that is still pretty active. I can fiter it at this point and put that aside for later incineration. Do you think I should keep dropping boards into it at room temperature until it stops reacting? Then go ahead with evaporating it and then incinerating it? I feel that evaporating and incinerating would be a waste of a lot of acid.

Thanks again

 

[butcher]

AP will not dissolve gold if you do not add too strong of peroxide, before working with it study it,

Just keep adding material to your leach you have now, just try and keep tin content to minimum if at all possible, a low heat will not hurt anything.no need to evaporate or incenerate at this point, after all of the nitric has reacted, you will need to filter, a large funnel and a ball of fiberglass may come in handy if there is tin on these boards.

Are you using city water with your nitric acid? Where these same boards treated with some type of HCl prior to this nitric leach, I am trying to figure out where you have chlorides and gold going into solution.

About 4.3 ml of 70% nitric acid and 4.3 ml water will dissolve a gram of copper,
Or
About 8.6 ml of this solution per gram of copper
At about 800 ml you have almost 100 times this amount of solution, I am not sure how much copper you have on those boards, but that is a lot of solution, 800ml/8.6ml = about 93grams of copper will dissolve.

megaplow, I thought you were going to do small experiments, with your studying, getting acquainted with processes before going large scale, small experiments you do not have big mistakes to deal with while you learn.

Also I would deal with the mistake I made before starting more projects to deal with.
Did you add a copper buss bar to the first solution tyou were working on?

 

[megaplow]

Current batch an Cl:
Looks like another oversight. I have been using 70% nitric acid with no water. All the water in my lab (I like the sound of that) has been distilled arrowhead. I don't see how any hcl could have contaminated my nitric solution. I assume the contamination is from the board itself when the green film lifted off exposing the glue or whatever was holding it on. Everything was fine till that happened. I have taken out the boards and set them aside, they were coated with slime. Is that slime tin or is it tin+gold?

Moving forward:
I fully plan on fixing this mistake before starting anything else. The reason I am using so much solution, is because I want it to completely cover my boards. My remaining boards have been broken into smaller pieces so I wont be using so much liquid. This is also the same solution I have been using for all my "going slow tests" it was not "fresh" when I started this batch.

Now:
Last night I put in a few more boards. This morning nothing was happening. It seems the copper from a few days ago plus these new boards may have exhausted the solution. I figure all the gold on my boards has a copper under layer. I am not sure where to go from here. If my solution is done reacting should I add a little water, filter it or dry it out and incinerate it? Is there a risk to filtering too early?

I just found this which is awesome:

Joe