Black Sands & Iron

[ARMCO]

I have been working with black sands and aqua regia. I have had a great deal of trouble due to he high iron content. There is a great deal of dissolved iron (bright yellow solution). I know metallic iron will cement out gold. So I'm wondering, is there a good way to dissolve the iron first, dispose of it, then dissolve the precious metals (PMSs) afterwards with AR?

 

[FrugalRefiner]

Welcome to the forum ARMCO. Since your thread isn't a tutorial, and you're dealing with black sands, I'm moving your thread to the Prospecting, Mining, Ore Concentrates & Geochemical section.

As far as putting unknown black sands in AR, I wouldn't recommend it until you know what's in them. There can be some toxic nasties in there that don't play nice with acids.

It has been said many times here that wet processing (acids) is rarely the best way to treat ores. Take some time and read through the threads in this section and you'll see how others have learned to deal with black sands.

Dave

 

[ARMCO]

Thank you Dave.

Yes, I have come at it by a few different angles. I have smelted the black sands as well as pyrites. I have used a ball mill and mercury with a retort, and I have precipitated some out of aqua regia but have never felt like the yield was what it should be. I always work with a fume hood as well.

I will do some reading here. Thank you very much again.

 

[nickvc]

ARMCO welcome to the forum.
As Dave has stated acids are rarely the way to go with ores, this isn't a slight at you but miners rarely seem happy with the results of their processing or even assays believing there are more values than they have recovered, if you have assays done then perhaps you can quantify your results. Even large professional mines do not get all the values and in some cases even fairly rich ores are not commercially viable to mine.
I applaud your efforts and hope you can find some answers to your problems.

 

[rickbb]

I don't recommend this on any kind of large scale until/unless you know exactly what is in your sands/ore.

But you can dissolve the iron with common HCL or Muriatic Acid. But it will dissolve other metals in the sand/ore as well, so caution is required.

 

[anachronism]

Don't throw random unassayed material into acids. Not if you enjoy life.

 

[Reno Chris]

The first step is always to have your material analyzed. Heavy mineral concentrates can have toxic minerals as has been mentioned. Not all black sands have much in the way of gold values - in fact, most do not have significant precious metal values. Make up a good sample, then get it tested by AA analysis to see what is in the sample. Then you can sensibly decide what to do.
Second, treating black sands with acids is a poor idea that almost never works. You can research through back threads on this forum and find a number of examples of folks who did exactly as you have done and ended up with no gold and a big mess. Why dissolve things like iron oxides that are best left as is?
So to review, this is a recommended process for treating black sands:
1. Find out how much gold and what other elements you have from a reliable assay lab.
2. If you have significant gold treat by careful gravity methods (like panning or a shaker table) to remove all the free gold particles. Assay again to see what values you have left.
3. If you still have worthwhile amount of gold in the material, do a fine sized grind of the sands and treat them with chemicals in a basic solution that will dissolve the gold. I wont give you any hints as to what types of chemicals can dissolve gold in a basic solution, because you should only try this if you have enough chemical expertise to answer the question without any help. Besides, this last step is almost never necessary.

 

[Eu_citzen]

I agree with the above and Reno Chris. I use the same procedure of testing as Chris.

 

[ARMCO]

Thank you to ALL who have responded. A few more bits of information.

Over the last couple of years I have worked on learning fire assay, smelting of ores, refining silver from various sources, using cementing with copper, (working on electrolysis), silver chloride with lye reduction. I got about just over 1/2 ozt of pure silver from 40+ lbs of old xray film once. AR refining of placer gold that I inquarted, as well as karat gold by same method. I have built a shop with fume hood and significant ventilation. I have a 12x9 hammer mill, 4'x8' shaker table, home made ball mill, Kress oven, Skutt kiln, blah, blah, blah. And I've been working with some miners doing some mining as well as trying to see what could be got from their "left overs." I had a number of samples assayed for gold content (not a full chemical analysis of content) and I've seen results from less than 4ozt/ton to as high as 11 ozt/ton. I'll run material on the through the hammer mill, the ball mill, put it on the shaker table, smelt it, AND I have been trying to see if AR would be viable.

I don't say any of this to try to impress or brag. I'm just trying to give a little background on me. Some areas I've done well and many other areas have big knowledge gaps. I expect that this group knows much, much, more than I do which is why I joined the forum. I have needed to pick brains that are much more experienced than I. So again, thank you very much for your responses.

Reno Chris, the basic solution you're referring to is probably cyanide leaching. I could safely do that, and have considered it, with the shop, fume hood and ventilation system, and respirator mask I have but I just hadn't made the decision to go there yet. It may be that is worth a try. I've just been stubborn about trying to make the AR work and it probably just boils down to bull headedness, lol. It just seemed like it should work but all the iron (as well as other elements) is playing hell.

I know of someone who has a reactor system (they patented and don't wish to sell unless it's to a large company), that uses HCl and chlorine gas on black sands and pyrites as low as 4ozt Au / ton. The gold is recovered from the gold chloride by means of patented resin beads and specific alleutions (sp?).

Anyway, that's more than long enough.

Thank you for the welcome to the forum and again, thank you all for your responses.

Oh, and I live in Alaska. ;-)

 

[ARMCO]

I agree with the above and Reno Chris. I use the same procedure of testing as Chris.

Hello Eu citzen, thank you for your response.

I just wanted to say "hi". I have a daughter who lives in Interlaken Switzerland. I know that isn't Sweden, but you're closer to her than I am here in Alaska. Anyway, "hi!"

 

[Eu_citzen]

I agree with the above and Reno Chris. I use the same procedure of testing as Chris.

Hello Eu citzen, thank you for your response.

I just wanted to say "hi". I have a daughter who lives in Interlaken Switzerland. I know that isn't Sweden, but you're closer to her than I am here in Alaska. Anyway, "hi!"

Alaska, huh? I've also lived above the arctic circle a couple of years - but in Sweden. :mrgreen:
Yes, I suppose Switzerland is closer then Alaska. :lol:

 

[ARMCO]

[emoji1360]


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