CAN I REFINE SLUICE CONCENTRATES WITH AQUA REGIA

[INDY864]

My first post. I am a self- employed industrial engineer. I have blended detergents for 30 years - BUT I am not a chemist. I have prospected my property in N.GA. for 40 years - BUT I have found only small amounts of color. Can I use Aqua Regia on my sluice concentrates to recover any unseen gold?
Thanks, Indy864

 

[Anonymous]

Yes but make sure you remove as much magnetite as you possibly can before proceeding.

 

[INDY864]

Thanks Mic,
Gonna find Hoke's book also.
Indy864

 

[Anonymous]

You are welcome,Heres a copy of hokes book.
http://goldrefiningforum.com/phpBB3/download/file.php?id=2480

 

[Harold_V]

My first post. I am a self- employed industrial engineer. I have blended detergents for 30 years - BUT I am not a chemist. I have prospected my property in N.GA. for 40 years - BUT I have found only small amounts of color. Can I use Aqua Regia on my sluice concentrates to recover any unseen gold?
Thanks, Indy864

I'm going to give you a rather more guarded reply than did mic.
It is safe to say, extracting values from ores isn't done well with acids. If your concentrates are primarily gangue, with very little value, you will most likely chase your tail endlessly. A great deal depends on the nature of your concentrates, so it may pay you to make determinations before jumping in with both feet, only to discover that you can't extract values due to circumstances that may be difficult to control.

You may achieve success by pretreatment with other acids, but you'll come to understand that it will be cost prohibitive, plus you'll most likely generate a huge amount of waste material that will be difficult to eliminate safely (and legally).

Cyanide is used for gold extraction for a very good reason. It works, unlike acids.

Harold

 

[Anonymous]

Tis so true,my point was to simply answer your question,however.....harold has addressed something that we need to make sure you understand.
Over 90% of all of the worlds gold that is recovered from ores, is recovered from a cyanide leach.Even a thio or iodine leach would be more beneficial than an acid digestion.It will take longer,but easily more efficient in the long run.

 

[butcher]

In my mind leaching concentrates implies free gold and black sands, free gold can be panned, or separated by other means, fine sluice, blue bowl, spiral wheel, shaker tables and so on.
This free gold can be refined (minimum gangue, but I would roast as precaution before dissolving) it is usually not pure gold and I would treat it as Karat gold, in quarter, and part silver with nitric then dissolve the gold.

Black sands, depending on your area Russia, some parts of Canada, southern Oregon they may contain the platinum group metals, but remember this is rare.
They may also contain some gold also rare.
Most black sands may be barren of value my thinking much more common.

black sands are Iron ore, usually sulfide ore, magnetite hematite and a half dozen other combinations, sulfide lock up values easily in any ore, this sulfide bond will need to be broken, in mining they roast the ore to drive off the SO2 gas heat treatments are an art as much as refining in the mining of ore.

Gold can be invisible in rock, or can also be visible depending on conditions it was formed or deposited.

As with refining and recovery Testing are your eyes, I agree with Harold, do not waste time and resource, without knowing it is worth it.
Testing may be done with roasting leaching and chemicals, or roasting and assaying

Go after the free gold you can pan and get with other means.

I do save my black sands but only the heaviest portions, most of them I just pan off and discard, the heaviest are panned again several times after grinding, to get some fine gold,
Then I save heaviest of black sand to process.

But I am in an area that is known for its gold and PGM, if I was in another part of the country or world I would do different.

A lot of talk about how rich a man can get from black sands, or by mining, but that is what most of it is a lot of talk, truth is I believe more men starved from mining than made money,
now people who sold supply's to miners, or who sold claims, or supplied women and song, they made money, also the big money men with lots of money to invest in manpower and equipment made money, but even of those also many many lost money, yes a lot of gold has been mined and to look at the numbers makes a man think of rich’s but miners are dreamers, some win some loose and some just have nightmares.
I think of Gold I think working very hard for very little but I just love it. Can not help it, it is just something about that metal.

 

[INDY864]

Thanks Mic, Harold, and Butcher,
I was hoping I could get some different info. But I had been resolved to hunt for serious color and give up the chemical extraction. Not too excited about cynaide.I still may try getting rid of magnatite then trying the aqua regia. The one good thing is N.GA. has some of the purist gold in the USA and world. Just gotta find it.
Nothing like focused trials to learn this stuff.
INDY

 

[butcher]

dig deep to bedrock :lol:

 

[Harold_V]

The most prudent thing you could do is to process a series of small samples to see how well it works. You may try various approaches, perhaps landing on one that works well. I have my doubts, but stranger things have happened.

The reason I have tried to caution you is that I have experience processing concentrates by acid. In my case, it was primarily a sulfide, mostly pyrite, but with a generous amount of gold included. Black sand would be different, no doubt, but to give you an idea of how I achieved success, all of the material (already crushed fine and classified---no large pieces) was roasted to redness on a stainless steel sheet, heated from below by a melting furnace. It was well rabbled.

After roasting, the material was digested in HCl. A great deal of the material was eliminated, but it also exposed yet more of the sulfides, which had gone through the roast without giving up sulfur. The material was roasted a second time.

The second roasted material was then digested in HCl once again, and, just as before, reduced in volume, but exposing yet more sulfide. It was then roasted once again, for the last time. After digestion, all that remained was bits of rock and gold. What started out as almost ten gallons of material was reduced to slightly less than a quart, which yielded something greater than six ounces, at least as I recall. This was MANY years ago.

Bear in mind, I was buying HCl for $57 for a 55 gallon drum.

Harold

 

[Shecker]

It is also important to remember than when wet magnetite carries a very high ionic charge that can hold fine gold in a tight bond.
But this charge is destroyed by thorough and complete drying. Then very carefully separate the magnetite by lifting it from a widely spread out sample of black sand. Drop it, spread it out, and lift it three times. That should render the magnetite clean of non-magnetic material.

Second extremely fine gold can have a black coating on it because of minerals such as manganese, rubidium, and few other rare earth oxides. Sometimes a dilute nitric acid wash can clean up these oxide coatings and sometimes it doesn't. Good luck with your project.

Randy in Gunnison

 

[INDY864]

Great info, Harold.

 

[INDY864]

Thanks, Shecker