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Geowizard

Gold Refining

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     It is in my own experience that if I hold the flame on the button until completely molten and it starts swirling round and round the impurities have time to coagulate and will rise up from the center of the button and settle on the surface as slag. It will be like a big black blister on top. Once cooled, it usually breaks off easily with a good tap with a small hammer, etc.. But trust me, I find that experiencing this visual is very addicting!----K Rose

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I am not speaking of the black material that is still showing, I'm asking about the intricate design on the gold itself. Lines and cross hatches all over the surface. Is that normal? I wondered if when cooling in the borax it crystallizes in this manner.

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Gold and most other metals will dissolve in aqua regia, and gold can be selectively precipitated with sodium meta-bisulfite.

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There are various methods of refining gold, and its a lot about chemistry.

There is a whole forum about refining gold that can be found with Google.

Dissolving gold with Aqua Regia and then precipitating it with sodium meta-bisulfite is a common method.

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 Lemon juice will neutralize acids.

 Wrong. Re-start from scratch and try again. Lemon juice is itself acidic and no, it does not neutralize acids. At best it can buffer some acidic solutions.

 

Additionally, some neutralized solutions are still chemically reactive - as an example if a solution is neutral but strongly oxidizing. 

 

Refining does require an understanding of chemistry.

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The basic concepts of pH -

 

Pure water has a pH of 7 and is neutral.

 

Acid solutions have a pH of numbers lower than 7.

A pH of 2 is a fairly strong acid. Saying a lemon juice solution has a pH of 2 and is less acidic means only that even stronger acids exist. Lemon juice is acidic, but stronger acids do exist. That does not mean stronger acids are neutralized by other strong acids.

 

Solutions of a pH of greater than 7 are considered basic. Really strong bases may give readings as high as pH of 14. Bases will neutralize acids. Things that give basic solutions include (among others) sodium Hydroxide, bicarbonate of soda, and trisodium phosphate. These will react to neutralize acids.

 

A basic concept of chemistry is that acids and bases neutralize each other to produce water and a salt.

As an example, Hydrochloric acid is a very strong acid. Sodium hydroxide is a strong base. Mixing the two (safely) produces sodium chloride (salt) and water.

 

Again, in chemical refining, one should have a genuine understanding of the chemical reactions involved.

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Digression of discussion;

 

The subject of gold refining is digressing into a debate over whether a less strong acid (lemon juice) will dilute a stronger acid.

 

There is no point in trying to discuss a subject when the administrator intervenes for the sole purpose of argument. 

 

- Geowizard

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No, I am just correcting the statement you made that acids can be neutralized with lemon juice which was just not true. You have now erased that from your post, but I am sure a number of readers saw it. Also providing additional information about the basic concepts of pH so you and others can better understand it.

 

As I have stated, in chemical refining, its important that one should have a genuine understanding of the chemical reactions involved.

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