# Help needed



## CBS (Jun 3, 2011)

I am fairly new to the gold recovery processes. The test I am currently using was referred to me as a "hot leach". The process is for testing purposes. Using a mixture of 500ml of distilled water, 50ml of Hydrochloric acid and 150g of the ore I am testing. I am heating this mixture (but not boiling) for 2 hours with constant agitation. After which I am filtering to seperate the ore from the solution of water and acid. I the take the water/acid solution and add in 20ml more acid and 10g of zinc powder. The gives me a black "sponge" material. I filter the material and then wrap the filter containing the sponge in lead wool. and cupel it. I have had decent results but the process of adding acid and zinc to recover sponge can be done several times. I there a way I can improve my formula to recovery all the "sponge" by processing it once instead of repeating the process?


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## Harold_V (Jun 3, 2011)

The process you're using doesn't make a lot of sense. HCl does not dissolve gold, nor silver. What is your objective?

Harold


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## Richard36 (Jun 3, 2011)

Hello CBS,

Welcome to the forum.
You will need to use Aqua-Regia to do what you are trying to do.

Harold, 

CBS is trying to use AR to take all metals into solution, then zinc them out as a precipitate, then melt the precipitate with lead in a cupel, thus using the cupel to blotter off the zinc along with the lead to leave a dore bead.

What he's trying to do is pretty close to what is done if doing a Scorification Assay, combined with Industrial Cupelation.

He is attempting the expensive, dissolve everything, and then precipitate all metals from AR type of recovery method.
Then use a modified scorification assay/industrial cupelation method to recover a dore bead, though I don't think it's working out for CBS being that he's only using Muriatic. 

It would work with AR, but would be expensive, and impractical.

Just my thoughts on the subject.

Sincerely, Rick. "The Rock Man".


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## CBS (Jun 3, 2011)

Thanks for your responses. I will give the aqua regia a try. Although I wouldn't say that the method I am using is completely ineffective. I am able to recover PM beads from my cupels. Will the aqau regia allow me to recover all the PMs with one reaction rather than repeating the process?


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## Richard36 (Jun 3, 2011)

Aqua Regia will allow you to put all metals within solution, and with powdered zinc, 
you drive them all out of solution as the precipitate you produced. 
In effect, that makes part of what you're doing similar to an Aqua Regia assay on an ore.

Sincerely, Rick. "The Rock Man".


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## glondor (Jun 3, 2011)

Hey CBS Welcome. I am no ore expert, I have learned what I know from this forum. So>>>> what I know is, There are many many methods of recovering values from ore. The methods are fairly ore specific. The key for answers would be to post some photos of the ore, an assay if available, and let the rock experts kick it around some. Be prepared to answer specific questions and follow some test procedures to determine the best method. 

If you look for ORE in the search box you will find many threads and you will see the many methods required for the different types of ore. 

My basic understanding is that Aqua Regia is NOT a viable method for ore, although it may be used in the specific process somewhere, IE after perhaps crushing, milling, roasting. 

There is a method for your ore i am sure, The idea here is to attack it with knowledge and a plan, in order to minimize cost and waste and maximize return. 

What I am saying is you may end up with milling and panning and a shaker table rather than chemicals. Good luck. Enjoy the challenge.


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## Reno Chris (Jun 3, 2011)

I recognize what you are doing - its kind a bizarre version of what is known as a chitty assay. Usually these types of assays are done on water solutions which already contain dissolved precious metals. They are commonly done on pregnant cyanide solutions - we used them regularly at a heap leach project I ran to test how much gold and silver was in our cyanide solutions. (Special Note: *NEVER, NEVER add acids like HCl to cyanide solutions* - the gas it gives off will kill you immediately - its what they use in most gas chambers to kill convicts). Thin lead sheet can be used in place of the lead wool you are using. 

As the other posters have said, HCl will not take up precious metals into solution. So the first part of what you are doing is just wrong. Even oxidized silver minerals like Cerargyrite will not go into solution with HCl as silver chloride is insoluble. Gold would only be taken up if you were to add something that would generate free chlorine. Cyanide or aqua regia would bring gold and silver into solution, but only depending on how fine you crush the material, how coarse the gold is, how long you allow it to digest, etc. 

Long story short: you need to study a book on assay methods and chemistry. The assay recipe you made up or were given simply wont work. Assaying is an art and some understanding of the chemistry of ores and what you are doing is necessary.


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