# Spot test pictures of gold in an granular magnetite ore



## Quwannar (Sep 10, 2017)

Dear friends,
i found a massive and granulated magnetite ore in a river bed. its about 50 meter long and 20 mt wide. in a hole nearby river edge, i collected approx. 10 kg of black sand. İ screened all of the black sand and some free quartz particles minus 30 mesh. When i looked into samples with a 1x100 magnifier i saw that all black grain is encrusted and stained with micron gold and silver spot disseminated onto magnetite particles. There was also no liberated free gold and silver grain in my pan. İ decided to make a spot test with aqua regia and sncl2 in order to test of gold or not. 
Could you please tell me that if iron content was so high, would spot testing give the same purple color.?
Lets assume that micron gold was densely in magnetite ore then how could we sperate gold from magnetite?
Any helps would be appreciated.
Please note that particle size of gold and silver is below 75 micron.


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## eaglewings35 (Sep 10, 2017)

That could be a false positive result, because iron will cause that same yellow color.
But with a stannous test, if it is iron you won't get a color change.


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## Lightspeed (Sep 10, 2017)

For a primary recovery process, a heap leach will be the easiest and most economical, I doubt you will get approval for that if it's near a water course, in that case, the ore will necessitate removal for treatment, depending on your local laws doing that in a water course may not be approved either.

If you want to do testing/assay, I would do by bottle roll done on a sample grid, samples will need to be taken at different depths, covering the deposit to get an average of your total PM.


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## Quwannar (Sep 11, 2017)

eaglewings35 said:


> That could be a false positive result, because iron will cause that same yellow color.
> But with a stannous test, if it is iron you won't get a color change.


Dear Eaglewings35;
İn all circumtances, Does a stannous test determine just the gold content? Does it properly work for gold despite of high iron content.
There was a densely reddish color as well as yellow at the aqua regia solution after 5 minutes boiling. At the stage of filtering, Reddish dissappeared. And when i dropped two drop of sncl2 and slightly vibrated solution then i suddenly got cassius purple.


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## Quwannar (Sep 11, 2017)

Lightspeed said:


> For a primary recovery process, a heap leach will be the easiest and most economical, I doubt you will get approval for that if it's near a water course, in that case, the ore will necessitate removal for treatment, depending on your local laws doing that in a water course may not be approved either.
> 
> If you want to do testing/assay, I would do by bottle roll done on a sample grid, samples will need to be taken at different depths, covering the deposit to get an average of your total PM.


Dear Lightspeed;
The sample i collected is magnetite and weathered by forces of water. So all of them turned into granulated and fractured form. Also no muscovite and no pyrite whitin magnetite. After primary crushing with a impact crusher, they can be easily grounded in a ball mill and İn my previous experiments with a pan, we did not observed free gold particles but there were small silver flake. When we tested the mercury, mercury was attacking particles and trying to capturing the magnetite particles was suspending on the mercury. İf i reduces the particle size of grain in ball mill, amalgation may work better. 
What about centrifugal seperator for micron gold separation to make mass reduction? And then magnetic separator. 
As far as i read the post of goldrefiningforum family, chemical treatment of gold in magnetite was so tricky and problematique.


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## Lightspeed (Sep 11, 2017)

You are dead right, treating iron oxides can be difficult and an uneconomic recovery for a small operator. 

You could mill the material, the reason amalgam is difficult and not sticking is due to some staining of oxides on the gold, this may improve after milling, but still generally is painful after the effort, this same reason goes for cyanide leach, in fact it can be difficult either way.

As far as gravity concentration through a wet plant, this also may be a painful process, milling may or may not help with separation of values from gangue given the nature of the ore and particle size of the gold.

This is why I said heap leach, with sampling by bottle roll. Essentially the bottle roll will give an indication of how well the leach will do on the ore by testing its refractoriness, I would forward samples both in the state the ore is in without milling, and samples after milling. 
Ball milling/amalgam would be ideal and very easy with a minimum setup cost if you have the plant, the trouble is the oxides on the gold and whether or not this improves your recovery.

Saying which one of these process runs will achieve a better result is dependant on the ore itself, obviously considering environmental and economic factors for both recovery procedures, either way you still may only achieve a 30-40% recovery rate.

There is a bit of testing by the above methods to see what you can achieve economically. You could also have assay done and sell the ore or claim and then someone else can deal with it.

Edit to add: you have stated there is no free gold, magnetic separation will not work in tha case regardless of milling. Short of roasting your magnetite to convert to hematite then cyanide leaching, I think the already mentioned processes will be the only viable and economical choices pending assay for a small operation.


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