5 year old buckets of ferric chloride and gold solution...

[crip53]

Ok...need a little assist here....and thanks in advance for any ideas

Back 5 years ago, I went into a bit of a craze trying out various methods to strip fingers and chips with various methods.
During one of my frenzies, I did about 5 gallons of ferric chloride over a bunch of finger and chips - the idea of course to remover the copper and leave the gold.

Well, things changed in my life and I never got around to doing anything with that liquid. I do remember that I tried to filter a little of it, but is was way to thick and it clogged up the filters.
So, I just popped the tops on the buckets and they have been sitting ever since.

Well, now I have a little time on my hands and decided to see what I can do with this stuff.

In one of the extra buckets I had for some left over ... about 3 inches or so in the bucket... I dipped a piece of aluminum heat-sink in it, and it started to get hot and foaming. It also created a black residue to the heat-sink.

Needless to say, I did a little checking on the net, and read that it was reaction that should drop the copper...and the vapor/fumes were just water vapor since there was no such thing as aluminum hydrogen gas.

Anyway, reading a little on here, I seems that doing a PH raise my just drop everything out.

Here are my questions: When I have swirled out the bottom of a shallow bucket of this mixture, there is a golden bit of swirl in it...no signs of any flakes. So, over time, has the ferric chloride dissolved the gold?

Is raising the PH the best way to drop both the copper and gold, and then smelt the two together in my furnace...which, to me, would make the gold settle to the bottom of the mold when poured...and then I could cut that section out and re-melt, drop into water into bb's and then cyanide the gold away from the copper.

I do have a bunch of aluminum heat-sinks from a bunch of computer scrap...but it would seem like the aluminum would just become an additional contaminate.

Does any of this make any sense? Or do you have any suggestions.

 

[kronix]

it seems the iron in your solution is plating out onto the aluminum, as aluminum reacts quite easily with HCL.

i think it would have been better to dilute the solution, until it was more free flowing, and syphon/pour off the top bit of liquid, saving all the sediment in the bottom to process. at this point you have remarkably less liquid to filter, and you can dilute again, each time making it easier to filter foils from solution as well as making most of the fine gold settle if you give it 10 mins to sit after each dilution.

adding aluminum to the mix is probably going to make things worse. if your worried about there being dissolved gold in solution you could save all washes and cement with iron, then dispose of wastes properly.

- Ian

 

[butcher]

The aluminum will cement gold copper iron and other metals from solution, the aluminum will also form a gel in solution that can trap values, I would not add any more aluminum.

Also it looks like you were adding the aluminum to solution indoors, I would not do that you may get a high concentration of hydrogen gas which could be dangerous.

The iron chloride solution will dissolve copper (copper etch solution), using copper in the solution will saturate solution and if any gold was dissolved it would cement out of solution.

(Iron if used, would cement copper, this solution can hold a lot of copper and you would have to re-dissolve large volumes of copper again to get to your gold).

After cementing out values using large pieces of copper, and no more copper will dissolve, and the solution has been given plenty of time for fine powders to settle, carefully decant liquid from settled powders to another bucket, do not disturb powders, I would probably decant down fairly close to powders, taking a sample of the decanted solution dilute it some testing with stannous chloride (it is highly unlikely you would get a positive test at this point but it is good practice using your test solution).


Rinsing the powders from bucket corning casserole dish the water will help to dissolve some salts and allow you to see powders better, allow this to settle well and decant solution to second bucket, outdoors on a hot plate add HCl to the powders and bring heat up to just under boiling. Add a little water (not too much) and low heat, keeping the solution as hot as possible but also letting powders settle well, decant this solution to a collection (settling jar after any fine powders settle that may have been picked up in this jar, decant solution to the bucket, rinse powder from this jar back into your main powders).

Now give the powders boiling hot water washes till the wash solution clears, again lowering heat and letting anything not dissolved to settle well, decanting into your settling jar, on a double burner hot plate I sometimes use a Pyrex coffee pot kept warm to decant my solutions into first the heat keeps the lead crystals from forming and any gold that may have been picked up to settle, after settling the liquid is then poured to my selling jar so solution cools and forms lead chloride crystals. Before decanting the water to the waste bucket.

The powders after washed well, I would mix up a solution of caustic soda and water, the sodium hydroxide will help to neutralize the powders, this will form a salt water solution as metals give up the chlorides to the sodium, the powders can also begin to form hydroxides and oxides, several boiling water washes to wash out all of the salt water till water comes over clear (same thing decant warm after powders settle).

On low heat dry powders, after dry raise heat keeping powders crushed and stirred bring them to high heat on the burner and then use a propane torch to bring these powders red hot, keep them red hot until no more fumes are emitted usually about 30 minutes, let them cool, these powders are your values, they can be saved or left in the dish for further processing.

If you haven’t studied enough yet to know what to do next, I would just put the powder in a jar and save them till you read a little more on the forum and in Hokes book.

Add old scrap iron or steel to the waste bucket, to cement out copper, and read dealing with waste in the safety section to get a good understanding of how to process your waste solutions.

 

[crip53]

First of all thanks for the replies..

I have this stuff in my shop...4000 sq ft with 24 ft ceilings with 3 - 10 ft long ceiling vents....and 14 ft sliding doors on each end and fans. So, a little gas is not a big problem. But understand, I ONLY put that piece of aluminum in the bucket for a minute or so....not intending to leave it there. Just wanted to see what the reaction would be since I had read that aluminum would drop copper.It was just a short test.

Plus, I do have fume hoods when it is time to get serious about this. It is NOT a high priority in my life...but would like to get rid of this stuff instead of storing it collecting dust. But, there is money in those buckets, so will piddle around to get it out.

Ok...let's see if I've got this.

I need to dissolve lots of copper to saturate the solutions to drop out any dissolved gold until no more of the solid copper will dissolve in the solution.

Then decant off the liquid to leave the powders to settle out...etc. And work towards getting the gold.

I am going to copy and keep your comments for reference.

The only other question I would like to ask, what can I use to drop all the copper out of the decanted out solution? I could smelt that down and sell it for scrap too.

Would using something like soda ash, etc., to raise PH precip the copper out into a powder?

Thanks again....

 

[martyn111]

The only other question I would like to ask, what can I use to drop all the copper out of the decanted out solution?

If you use the search function, top right of your screen and search for the reactivity series, you will have a list of metals in the order of reactivity.
On that list find copper, then choose a metal which is higher in the reactivity series (is more willing to go into solution than copper) and cement the copper out of solution using the higher metal, much the same as you used copper to cement out the values from your previous solution.

 

[maynman1751]

by Butcher
Add old scrap iron or steel to the waste bucket, to cement out copper, and read dealing with waste in the safety section to get a good understanding of how to process your waste solutions.

Butcher already told you! Listen to this man. He is one of our brightest.

 

[butcher]

The washed copper metal powder (keep covered with water so it does not oxidize when dry in air or form copper carbonates) copper would oxidize easily when trying to melt it, this would burn up most of the copper, a flux with a lot of carbon (charcoal, or flour) can help take the oxides from the copper and air around the melt, a reducing flame on the burner or torch can also help when melting copper.

I do not know but with the price of fuel it may cost more to melt the copper than you could sell it for.

 

[g_axelsson]

Is raising the PH the best way to drop both the copper and gold, and then smelt the two together in my furnace...which, to me, would make the gold settle to the bottom of the mold when poured...and then I could cut that section out and re-melt, drop into water into bb's and then cyanide the gold away from the copper.

No, you can't melt copper and gold together and have it separate by gravity. It doesn't work.
The gold would form a solution in the copper, an alloy, with basically the same composition through the whole melt.

If you suspect that you have gold dissolved in ferric chloride I suggest that you test your solution with stannous chloride. It will tell you if you have any gold in it.
I always test every solutions before pouring it off, just in case I missed something.

Göran