Converting gold sponge to free gold

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kiwigold

New member
Joined
Jan 2, 2021
Messages
2
Hi Folks

Just joined as I am hoping one of you knowledgeable folks can help me. I am wanting to know how to turn gold sponge back into free gold. That is fine micro gold that has been amalgamated in mercury, then put in the retort, resulting in a ball of gold sponge. Usually I melt this and then sell to a gold buyer. However I have received a request from a gold collector. Who desires, that the micro gold be free running. The gold is acquired from a blacksand beach claim and the only way to treat it is with mercury to recover it. I seem to recall that I read, years back that putting the sponge in either lemon juice or vinegar will do the trick. But thought I would check here first. Would be grateful if anybody can help. I am based in New Zealand on the west coast of the south island.

Cheers Trev.
 
Give a picture of the sponge. Also I wonder if the black sand is finely ground, and no gold remains after mercury
 
I have no experience with this problem, however I would imagine that whatever black sand you could not retrieve with a magnet, you could dissolve in a weak HcL bath. But that is just my opinion.
 
Hi Again

No black sand involved in the amalgamation process, although the gold was obtained from running beach sand over plush tables with water. The gold concentrate obtained being a mixture of micro fine alluvial gold and black sand (Magnetite and ilmenite). This is then placed on a revolving amalgamator in a glass jar with mercury and water and tumbled for several hours. It is then removed, the blacksand discarded, leaving only the liquid mercury which contains the gold. The mercury is then squeezed through a fine cotton cloth, resulting in a gritty ball of mercury amalgam. This is then placed in a retort and the mercury burnt off(it is recovered). After this process you are left with what is termed gold sponge. Which is a ball of the original gold all stuck together and slightly dull. The usual process is to then melt this. But as explained I have a customer who would like it to be put back into its original composition, ie. Loose alluvial gold. Beach gold is smaller than a full stop . (or period}. I have attached a pic of a small piece of gold sponge.

Cheers Trev
 

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What you ask is not possible. Once you made an amalgam out of your placer concentrates, you changed the nature of your gold from fine, natural particles to a partially fused single piece. If you want to have only fine placer gold, you will have to learn to recover without the use of mercury, or any other chemicals.

Johnny5 suggested a weak HCl bath. That has its limits, and I would not use it if your goal is indeed keeping the natural nature of your gold. Placer gold is impure, typically with small amounts of silver and copper. An HCl bath would change that.

Having mined the beaches of southern Oregon and southern Washington, I know it is difficult to learn, but I still deal with several people who make a very good living doing so. The device used by most beach miners I know, to clean concentrates, is a Miller Table. No matter how you get your beach concentrates, the Miller Table will help you obtain clean gold.

May I ask what the current legal issues are in your country regarding use of mercury in recovery of gold?

Time for more coffee.
 
Looks as flotation may help, if the need is continuous. This includes conditioning and floating the fine gold particles
 
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