# Gold Extraction - help needed



## ezhil2146 (May 21, 2011)

Hello,

I am new to this forum. 
I have been working with a gold bearing material for past 6 months. It is said to contain gold in it. But could not identify the source of the material. I have about 3 tons of this material. 

I am posting details of my works done so far. 

The material is slightly wet and contains lot of fine sand/silica, carbon, some red colored particles (which do not react with any acids), some yellow colored shining particles(which is very brittle).

1. Qualitative analysis was done by EDAX and reported presence of Au, Ag, Pt, Fe, Ni, Zn,Mn, Si.
2. Quantitative analysis was done in external lab and by fire assay which reported 461mg/kg of said material.
3. After separating magnetic particles(10% was magnetic), fire assay result was 300mg/kg. and the lab technician told me that gold distribution within the sample is not uniform.
4. Finely grounded ore was concentrated using sluice box and it reported 40mg/kg. (failed)
5. I tried reacting material with Conc. HCL for removing base metals and residue was assayed which contains no gold.
6. No gold was found in Aqua regia process too. (done by gold scrap recyclers)
7. 100mg/kg of gold was extracted by a recycler( who uses molten lead for recovering gold, but not clear with what exactly he is doing) This recycler failed to extract on a larger scale(100kg processing)

I have been trying all these for past six months only with a hope that I will extract gold from the material. I don't want to leave it.

I wish anyone could suggest me the methodology to carry out.

Thanks in advance.

Regards,
kumar

Please limit your posts to one per subject. Multiple posts in various forums are not acceptable and will be deleted. 

Harold


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## Harold_V (May 22, 2011)

ezhil2146 said:


> 5. I tried reacting material with Conc. HCL for removing base metals and residue was assayed which contains no gold.


I have processed gold bearing ore concentrate by that precise method, including roasting for elimination of sulfides. 
Assuming you really had HCl, and did not manage to dissolve any gold that may be present, that should be sending up a red flag for you. In my opinion, you're not detecting any gold because _there is no gold to detect_. 

At this point, you'd be very well served to pay for a reliable fire assay. No process known to man will extract gold that isn't there. 

Harold


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## ezhil2146 (May 23, 2011)

Hi Harold,

What I meant to say with HCL treatment was this.
By washing with HCL, all gold was washed away in the solution. Two samples form same lot was taken for fire assay. One was raw which reported 300mg/kg. Another sample was washed with HCL, (only the residue was fire assayed) which reported no gold. I think that gold was washed away in HCL. 

Kumar


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## Reno Chris (May 23, 2011)

I think Harold is skeptical because gold does not react with HCl alone. If you treat an ore with just HCl, the gold that was there to begin with should still be there. 

The possible exception that could occur in some geologic materials is with ones that contain significant manganese dioxide. (MnO2 + HCl yields free chlorine, which is capable of dissolving gold). If that reaction did occur you would smell the unique odor of free chlorine gas. Since this is a "mystery material" we don't have any idea what it actually contains. 

When I first read your post, my thought was the same as Harold's - to question the assays which said the material is rich. I would agree with him that re-testing is in order before you put lots of effort into this material to extract gold that very possibly isn't really there. I would also recommend using an assayer different from the one which gave you the rich assays. 

Chris


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## goldsilverpro (May 23, 2011)

Sampling is everything. 

Describe your material in better detail. Is it all ground (or, not?) and, if so, what is the approximate particle size percentage spread? What was the source of the material?

How many samples were assayed to determine your results? How were the samples taken and prepared - the more detail, the better? If multiple samples were assayed to get the final result, what were the individual sample results?

An assay only tells you what is in that sample that you selected from the sample bag full that you selected from the pile. With uneven gold distribution, the sample next to the one you grabbed might assay zero. An assay is only as good as the sample. A poor sample gives a worthless and misleading assay. Sadly, though, sampling is not intuitive and it requires some math.


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## Traveller11 (May 23, 2011)

Hello Reno Chris
I'm glad I read your post. It may explain what happened with the experiment I described in the thread "Neutralizing Hydrochloric Acid".
As I described in that thread, I discovered a cemented sand and gravel deposit that appears to have been put down during glacial melt following the last Ice Age. It is just now being exposed at the high tide mark as the ocean erodes the shoreline where it is situated. 
There is no shortage of manganese in the groundwater in the vicinity of this deposit. This deposit is mostly black and looks like a two foot thick layer of black pavement protruding from the bank; although in places it is red as well. There is no shortage of iron in the groundwater, either.
I wanted to see if this deposit contained any PM's. I tried several ways to break it up and remove the oxides but found most not that effective. Frustrated, I put a lump of this material in a jar and covered it with hydrochloric acid. Black foam immediately filled the jar and, as you stated, there was a definite whiff of chlorine gas. I left it overnight and then neutralized the acid with baking soda and dilution with water. The sand I was left with, after washing, was the cleanest blonde sand I had ever seen. I screened it to 50 mesh and tried panning it. Although there were some fine flakes of what appeared to be mica (or pyrites) there was no gold to be seen.
Is it possible that my material contained a lot of manganese dioxide and that the PM's went into solution?
Regards
Bob


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## Oz (May 23, 2011)

Traveller11 said:


> Is it possible that my material contained a lot of manganese dioxide and that the PM's went into solution?


A stannous chloride test would answer that.


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## Reno Chris (May 23, 2011)

Traveller11 -

As Oz noted, a stannous chloride test would give you a definitive answer. However here is what I'd expect: no gold. There is lots of discussion on this forum about taking gold into solution and in many processes, that's exactly what you want to do. However with gold placers, its better to recover the gold mechanically - panning, etc. That's because coarse sized gold dissolves only slowly (remember these are surface reactions). My guess is that any placer gold that was in your sample would have survived the brief (overnight) exposure to free chlorine and shown up in your pan. In commercial gold extraction with cyanide, when larger gold particles are present in the ore, there are always separate circuits to catch the coarse gold before the cyanide circuit because the coarse gold dissolves so slowly. The cyanide can then work on only the smallest gold which will dissolve fairly quickly. 

A stannous chloride test would give you a definitive answer - but I'd expect a negative result for gold. 

Chris


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## Traveller11 (May 23, 2011)

That's just the thing, there is only ultra fine gold in this particular area. I believe these glacial deposits contribute to the beach placers we have here and all of the gold in them starts at about 120 mesh and gets much smaller. And, like most glacial gold, it is thin and flaky. 
The stannous chloride would tell a person for sure but I've already disposed of the solution once it was neutralized. I suppose I could go through all of it again but God what a mess it was. Oh well.
The important thing, I think, is learning that manganese dioxide and hydrochloric acid will have the potential to leach fine gold from an ore.
Bob


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## mikesmadness (Sep 30, 2011)

I am quite new here and am impressed with the wealth of knowledge that is inherent within this forum. It will take me months to digest what is available. To the point, I have several thousand pounds of pre-Nixon costume gold jewelry I wish to harvest the gold from. If someone could just give me a shove in the right direction I could start learning what is necessary and pick up the supplemental information along the way It would be appreciated!
Thanking you all in advance! Mike in NM


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## Palladium (Oct 1, 2011)

Gold stripping cell

http://goldrefiningforum.com/phpBB3/search.php?st=0&sk=t&sd=d&sr=posts&keywords=+%2Bgold++%2Bstripping++%2Bcell


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## Harold_V (Oct 1, 2011)

Yep, what palladium said. Gold plated jewelry typically has very little gold applied, so stripping is probably the only economical method to process. 

Harold


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