Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Dissolving Gold and Precipitating Gold (22 replies and 5 comments)

JohnnyD
6 years ago
JohnnyD 6 years ago

Muriatic Acid + Clorox Bleach is dissolving my gold, but Sodium Metabisulfate (stump out) is not dropping the gold back out in pure form it's only changing colors of my solution. no precipitation.

Maya Rothman
6 years ago
Maya Rothman 6 years ago

You probably want sodium hydroxide, a base, not sodium metabisulfate, an acid.

(unknown)
6 years ago
(unknown) 6 years ago

If you leach with aqua regis (nitric and hydrochloric acids), you can precipitate the gold with sodium metabisulfite (a reducing agent).

Mixing muriatic acid (hydrochloric acid) with bleach (sodium hypochlorite), you are freeing chlorine to attack the gold. You are making gold chloride. Try exposing the solution to ultraviolet light, to break the bond between the gold and the chlorine molecules.

R
Rooster
4 years ago

What is that doesn't work

JohnnyD
6 years ago
JohnnyD 6 years ago

Ultraviolet light comes from the Sun right? So set it outside?

Ok. I added sodium and potassium hydroxide to muriatic and bleach solution and it coagulated with a white look.

JohnnyD
6 years ago
JohnnyD 6 years ago

I  stnowopped using Clorox. I used only hydrochloric acid and used sodium and potassium hydroxide and bingo. Solution turn clear with brown sediment in the bottom. As I understand it that's my gold. Hopefully.

JohnnyD
6 years ago
JohnnyD 6 years ago

It also worked on the hydrochlorite mix but no near as well.

(unknown)
6 years ago
(unknown) 6 years ago

You should try to get a PH of around 1 before using SMB to drop the gold, By using sodium and potassium hydroxide you raised the PH. That is why it worked then.

JohnnyD
6 years ago
JohnnyD 6 years ago

Good morning friends. As an update, I am consistently dropping gold from hydrochloric With sodium hydroxide. However, I have noticed some different colors showing aside from brown. I have black. Blue and green. Any idea what these other colors may be?

Maya Rothman
6 years ago
Maya Rothman 6 years ago

The solubility of gold, wether by strong acids, cyanide, bromines, etc is a pH dependent reaction. Changing the pH is one way to accelerate or reverse the reaction (others exist). The colors are probably due to other metal ions present.

look at: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=the+chemistry+of+gold+extraction

(unknown)
6 years ago
(unknown) 6 years ago

If you want to leach gold you need an oxidizing environment (add chlorine gas or clorox) until you reach an ORP of 1000mV, at a Ph of about 5, hopefully warm temperature and you will leach gold. Once in solution, separate liquid from solids, reduce the ORP to 100 -500 mV using NaHSO3 and your gold will precipitate. Read chemistry papers between 1850 to 1930's....the old folks knew what they were doing.

Victor Bergman
6 years ago
Victor Bergman 6 years ago

Lye is sodium hydroxide. But the real problem is that your precipitant will not work if chlorine or any other oxidizer is present in solution

JohnnyD
6 years ago
JohnnyD 6 years ago

Thanks and your absolutely right.

(unknown)
6 years ago
(unknown) 6 years ago

You are right of course. I forgot to mention that the solution has to be free from chlorine and oxidizers first.

But to my experience the chlorine evaporates very fast and in addition one should always use the minimal amount of chlorine/Clorox that is needed to dissolve the gold. Do not use too much or it will take longer to evaporate. Also a persistent myth is the premixing of HCl+Cl or Aqua regia. That is a bad thing to do. Always estimate the amount of HCl or chlorine needed do not premix the dissolving solution no matter if 1:3 or 1:4 or whatever you find on the internet.

JohnnyD
6 years ago
JohnnyD 6 years ago

The ore I'm processing with HCI is just packed with platinum group metals and turns either a bright yellow or carat orange. When I precipitate with SMB THE solution fizzez yellow bubbles and the precipitate is orange as orange can be and sponges. When I precipitate with sodium hydroxide it turns dark brown or light brown with black specs in it.

C
Christian1111
6 years ago
Christian1111 6 years ago

hi guys, can please tell me how to separate gold from copper and silver? And anyone knows if borax separate copper from silver please? Thanks.

David
6 years ago
David 6 years ago

Use the Social Share Bar on the Left. Tell everyone you can about https://www.911metallurgist.com/metallurgy/ It's FREE & GOOD.

C
Christian1111
6 years ago
Christian1111 6 years ago

Thanks a lot my friend I'm working on what you sent me and is working great, there is just some little things I need to work on, I really appreciate your help my friend this things that I'm doing is keeping me alive because finally I have a goal in my life and your helping me doing it. Thanks a lot from my heart.

C
Christian1111
6 years ago
Christian1111 6 years ago

hi friends hope your all well, friends I'm trying to my a living from this work and I refine from computer scrap, can someone help me to find some good suppliers because just scammers I'm finding. Please if someone can please me I need some good contacts thanks a lot. ?

David
6 years ago
David 6 years ago

Find some good suppliers of what?

Use the Social Share Bar on the Left. Tell everyone you can about https://www.911metallurgist.com/metallurgy/ It's FREE & GOOD.

C
Christian1111
6 years ago

Of scrap Rams,CPUs ect...

C
Christian1111
6 years ago

If anyone can please, much appreciated ?

C
Christian1111
6 years ago
Christian1111 6 years ago

hi dear friend ? first of all I would like to wish you happy Christmas and a happy new year.

I need to know how to melt the borax from the gold after I melted, can someone help me please?

Thanks a lot.

C
Christian1111
6 years ago

Sorry.....How to separate the borax from the gold after melting? Thanks

David
6 years ago
David 6 years ago

Use the Social Share Bar on the Left. Tell everyone you can about https://www.911metallurgist.com/metallurgy/ It's FREE & GOOD.

David
6 years ago
C
Saxe
2 years ago
Saxe 2 years ago

Even though these posts I am commenting on today are 3 years old, people still read and rely on them.

All of the comments related to Johnny D's question concerning inconsistent results are good - but it is of the utmost importance that we determine the chemical composition of the "ore" AND whether or not Johnny has properly pulverized and cleaned his ore of various natural elements and compounds such as base metals, K+, P+, Mg+ and especially the great interfering and often ignored element Ca+. Nitric Acid is the only agent that will dissolve salts and base metals without dissolving fairly pure gold. Unless we thoroughly wash our ore with nitric acid, we will not be eliminating anything ... Regardless of how much gold might be present in our ore, unless the aqua regia (recommended over HCL & Bleach when dealing with ore rather than jewelry scrap) can freely react with the gold present, we will spin your wheels and get “consistently inconsistent” results that will drive us crazy. Our lab works microscopic Au, Pt, Ir recovery from desert ore and our standard procedures follow at least two HNO3 washings through fritted glass micropore filters (so not to wash away microscopic Au particles). The HNO3-washed ore - while remaining in the fritted filter - is then cleansed with boiling H2O. Even though using G4 fritted filter, microscopic Au gets through with the boiling water and precipitates on its own in the filtered H2O below. Finally, the undisturbed washed-ore - while still remaining in the fritted filter - is then directly subjected to “very hot” AR soln. The recovered beautiful yellow AuCl solution is then evaporated to remove excess HNO3 and reconstituted with H2O, monitored with electronic PH /MV meter to ensure a PH of at least “above 1.9” - then finally subject to SMB ppt. This procedure consistently yields 65-80% Au with remainders of Pt and Ir. A comment about PH’s as related to strong acid solutions. Strong acid solutions have PH’s that go “below” the standard 1-10 scale, so by the time you neutralized a strongly acidic AuCl solution to a PH of 1.9, it is out of the strong acid range and thus practical for ppt with SMB.

r
randy N
2 months ago
randy N 2 months ago

so when cleaning the gold dirt with clean muriatic acid which is the gold and which is the other metals,,. i added fresh muriatic started turning dark with a light colored sedement in bottom this is muriatic/nitric dropped with lye and cleaned with fresh muriatic

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