Dissolving gold without heat

[RowanGroeneveld]

Hello guys, i'm new to this forum so excuse me if this isn't the right place for this topic. I have a large batch of crushed IC's (about 4 kg). As this would take a lot of acid to dissolve all of the base metals & gold, I decided to put all of the IC's (cotaining gold) in a container with AR. I knew it would take a long time before all of the gold would have been dissolved but; It has been 4 days now (the solution hasn't been on any heat) and I can not see any gold foils floating anymore, plus the bubbling has stopped. My question is; how long does it normally take to dissolve gold in a dirty solution, without any heat?

 

[nickvc]

Welcome to the forum.
The answer to your question is not easy to determine as there can be many variables to influence the time needed.
In honesty I would advise using heat to make sure the all the values get dissolved, failing that agitation of the solution would be useful to make sure all the pieces are exposed to the acid.
Is there any reason you have decided not to heat the solution?

 

[g_axelsson]

What type of IC:s?

... and where did the floating gold foils came from?

You first say that it would take a lot of acid to dissolve the base metals and gold, then put it all in AR. Are you expecting to just dissolve the gold but not the base metals? It doesn't work like that, gold is the last metal to go when any base metals are already dissolved.

As this would take a lot of acid to dissolve all of the base metals & gold, I decided to put all of the IC's (cotaining gold) in a container with AR.

Only way to be certain to when all gold is dissolved is to remove the acid and dissolved metals and do another AR treatment. If that comes up negatively then all the gold dissolved in the first run.

Have you tested the solution with stannous? If there is no gold in solution it have cemented back onto the base metals. Then it will not look like gold any longer, just as brown or black blobs, crusts or fine powder.

Don't do anything rash, put the container in a safe place (remember it might give off gases and acid vapors so probably outside with saran wrap over the opening to keep trash out while not building up pressure).
There's a lot to learn about storing acidic material so you don't destroy your car or tools if stored in the garage. Expect anything in the vicinity to rust.

Hardest thing for a newbie is to put down the scrap and start to read. The urge to experiment is high but so are the risk of making stupid mistakes and losing your gold or worse, hurting yourself and other people in your vicinity.

Göran

 

[Iggy-poo]

A good rule of thumb is to double the reaction rate with each 10 degrees Centigrade rise in temperature, everything else being equal. It doesn't take long to see that things start increasing rapidly. the downside is that species that contribute to the reaction begin to boil off with increasing temperature, so there is some advantage to keeping the temperature within limits.