high gold grade in clay oxidation zone..

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Quwannar

Active member
Joined
May 26, 2017
Messages
35
Dear Friends;
Some friends brought the clay sample to search the gold presences. The yellow clay is very impure like a soap. No visible gold in the sample.... İ prepared 250 ml of full strength aqua regia (AR) for 20 gram of clay. All sample easily disolved in AR without clogging. And Stannous chloride test appeared very dense purple color. No brown fume observed in AR reaction stage. Can some kind of clay be leached via ferro/ferric cyanide or saline /hypoclorite vat leaching method. İf yes, Could someone please advise the begining reagent recipe and their ideal reaction conditions. İ think that gold grade of clay sample is about 0.8 %. İ virtually concluded this outcome from color comparisons of stannous chloride tests beetwen standart Au test solution and clay sample.
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Best regards
ErdemIMG-20181107-WA0004.jpgIMG-20181105-WA0003.jpgView attachment 1View attachment 2
 
Before you get too excited about your ore sample you need definitive proof that you both actually have gold in your sample and at what level it is at if it is actually present.

Run your aqua regia digest as previously but simmer the pulp until the fumes change from brown to white.

Allow to cool and filter through a Whatman No1 or equivalent filter paper.

Water wash the solids in the filter paper to get all of the gold values into the clean liquor.

Make your filtrate up to volume, usually 200 or 250ml depending on rinse volume.

Take a sample of this liquor to someone who has an AAS unit with gold standards and background correction, even better is someone experienced in organic extraction, usually DIBK/Aliquat 336.

This might be done at a commercial lab, through someone you know at a university or similar or a private company's lab.

I say to run the sample through AAS only because it is cheaper than using ICP, for what you want to know there is no difference between the two methods.

When you have gotten the assay results and done the maths to get your gold grade you will be in a position to look forward for processing options.

Processing options will start to cost real money, lay out the small amount of assay cash now to see if you really can justify the larger expense.

Deano
 
Dear Deano;
İ would to thank you for your great effort to inform all of us. İ sent the clay sample for just AAS assay.
İf you have more time, Would you please tell about method and procedures of solvent extraction by DİBK of AR digestion to identfy the gold presence. İf you have time. And another things in which can be an evidence of more gold in clay sample is attached photos of smelting of 50 gram yellow clay in tourch flame with just 50 gram of anhydrous borax. Can accumulation of yellowish metallic stuff on the slag be gold alloy?
İf i look at it with a 1x22 magnifier, i can see the brillant and dense segregated but small globes on yellowish part of slag.
Best regards
Erdem
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Flame AAS is subject to interferences from several metals even with background correction on.

The major interference in assay of ores is iron.

The reading gotten from iron in solution is not additive to any actual gold reading.

For example, if the iron in solution gives a false gold reading of 0.020 then this reading will mask any true gold reading lower than 0.020.

Once a true gold reading is greater than 0.020 the false gold reading does not affect the true gold reading.

If the gold level in an ore is low then there is a good chance that any false gold reading will be higher than the true gold reading and thus lead the operator to assume a higher gold level in the ore than is actually present.

In order to minimise any errors from these interferents, techniques were developed to separate the gold in solution into an organic phase, this organic phase being one which had minimal adsorption of the interferents.

The organic phase was then read on the AAS using the relevant gold standards for that particular organic phase.

The gold industry standardised on an organic extractant comprising DIBK as the water insoluble carrier phase with 1% Aliquat 336 as the gold extractant.

The usual reference term is just DIBK extraction.

The DIBK is added to the digest liquor in exact fixed ratios and is shaken in extraction tubes for fixed times, many labs have their own preferred ratios and times.

After shaking, the DIBK is allowed to phase separate from the leach liquor, this is often let happen overnight.

The DIBK is then read on the AAS against standards prepared using the same DIBK formulation.

Basic maths then allows the gold grade of the original more to be calculated.

It would be a much braver person than me who would pass judgement on a photo of an unknown material produced by an unknown method.

I would always perform proper assays if there is more than idle curiosity involved.


Deano
 
If that particles can be extracted with a little cyanide + NaOH + H2O2 there is an additional proof for gold
 

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Dear Friends;
Thank you very much for your practical information.
İf İ dissolve some ore sample on hot Aqua Regia for gold presence, how many thours or day can be kept gold complex within AR solution without redissolving for AAS reading. Because İ have no AAS equipment. İt is required at least two days to sent AR solution to the commercial lab.
As for cyanidation pocess to test the gold, i ordered potassium ferrocyanide and 400 nm of UV lamb as well as zinc rod to see the gold presences in our sample. So how long does it take to complete cyanidation reaction to see the gold on zinc rod.
Best regards
Erdem
 
If you filter the pulp straight after cooling of your aqua regia digest, the filtrate will be stable for at least two days providing it is not subject to extreme conditions such as sitting in an enclosed container on a very hot day.

Cyanide assays are usually run as bottle rolls, 100g ore in 300 - 400 ml water with 1g sodium or potassium cyanide rolled in a 2 litre bottle for 24 hours.

Weights and volumes must be exact, ore samples must be dry before weighing.

After 24 hours the pulp is filtered and the liquor analysed by AAS.

Deano
 
Dear Sir Deano;
As you told us that thiocyanate leach is carried out with 5 % of sulphuric acid in acidic conditions. Can thiocyanate leaching be run for ore concentrates in which have high gold grade in laboratory conditions? Without AAS reading, Can we visually observe the gold precences in thiocyanate leaching with known precipitating reagent like Copperas, SnCl2. If not, Could you offer another stuff in which can result in colour differences in thiocyanate leaching liquour?
thank your very much again and again for all of your valuable contributions to me.
with my great respects,
Erdem.
 
All methods of dissolving gold will require an AAS assay of the filtrate to give you reliable numbers.

Aqua regia assay as described above can give you very rough indicative results if the nitrates are removed by simmering and then filtering before stannous chloride is added to a drop of the clean solution.

I say rough numbers because when you digest an ore sample there will be many metals put into solution, many of these metals will interfere with a stannous test.

Unless you have the unlikely circumstance of an incredibly rich ore sample then displacing the dissolved gold onto a bar of another lower EMF series metal will have so little gold present that visual inspection is worthless.

There is always a reason why certain assay methods are used in the mining industry, for gold there is always an instrumental finish for aqua regia or cyanide leaches.

This has proven to be a robust method with absolute certainty around the results.

All other methods are not reliable, you can get false positives and false negatives visually.

Deano
 
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