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Twobrothers

Member
Joined
Jun 20, 2017
Messages
12
Hi everyone. I've been lurking and learning here on gold refining forum for about a year now. I've been prospecting and developing a few gold deposits and I am at a point where I have a good source of quartz based material with visible gold and some locked in sulfides. The gold is very fine. I haven't had success with physical recovery methods. Some success on a small scale with amalgamation. I've investigated chlorination, and cyanidation thoroughly. Done some experimentation with chlorine. Experienced some trouble keeping the ORP (>1000) and Ph(>7.5) in the right ranges. Chlorine is really nasty stuff. Caught a couple strong wiffs once or twice and called it quits. Not really willing to deal with cyanide. I am curious on people thoughts about thiourea. I know it exists but not much about the practical side of the process. Are there other processes that can be practically executed by the layperson with the necessary research, understanding, experimentation and access to resources? Are there people in the western united states who will smelt/ leach/ purify/ work with raw ores? Average grade by fire assay is about 1oz/ ton more or less depending on wall rock/ gangue dilution.
I crush the material to 1/8" minus then grind to powder (around 40 mesh). Could grind finer. Finding the gold is only half the work. Getting it to a marketable form takes respectable effort. So far been the funnest hobby I've ever had. Would like to see some gold for the effort. Thanks for sharing your knowledge and experience.
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Still here with gold in rocks. Found pockets with abundant visible gold. No professional assays on that material yet. Beginning to learn how to do my own fire assays. Read Deanos posts. Man knows some stuff about chlorine leaching rocks.
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Sigue volando con tu hermanito "El Capitan". Dile que es mejor si compra una batea y empieza a caminar. Antes del siglo 23 seguro encuentran la mina que buscan. Mientras tanto, sigue nombrando ranas y vegetales... :G
 
Can you translate that, please.

I don't trust google translate is doing a good job on this...
"Keep flying with your little brother "El Capitan". Tell him it's better if he buys a punt and starts walking. Before the 23rd century they surely find the mine they are looking for. Meanwhile, he continues to name frogs and vegetables ..."

Göran
 
Oh and as to thiourea...works great very fine gold. Better than cyanide. Easily recovered with zinc or borohydride. Of course one can always work with base hydrolysis and redissolve the sulfide in aqua regia, kill nitric, dilute and chill, filter and precipitate the gold with hydrazine salt. Much more expensive

Pregnant solutions may crystallize and are very orange red.
 
Lou said:
Grind it up and leach it!
Easier said than done!
Here's what I've tried so far: Into a five gallon bucket with a lid I added one gallon of 10% sodium hypochlorite solution, 1 cup of NaCl and twenty pounds of crushed ore (minus 20). I slowly added diluted hydrochloric acid stirred tested with litmus paper and added more acid until reading a Ph about 6. I checked on it hourly for the first 8 hours stirring and adding water and acid if necessary to keep the Ph at around 6 and sprinkling in a little calcium hypochlorite (from shock treatment MSDS for which listed 48%calcium hypochlorite and the remaining % NaCl) from time to time to maintain some chlorine scent in solution. Enough to smell wafting off the leach. After two days of maintaining the Ph best I could and adding fresh hypochlorite I let it settle out and I siphoned the liquid through a pvc column (1.5"x 16") filled with washed activated carbon. I burned the carbon to ashes and smelted about 25 grams of ashes with sodium carbonate borax litharge. Cupeled the lead and got about 2 milligrams of a silvery colored bead.

The second time I basically did all of the above but when I filtered the liquid through the pvc column filled with activated carbon it started reacting strongly bubbling heating up and giving off chlorine gas.

I was very careful to exclude any sources of carbon in the leach. Probably be a lot better if I had an ORP/Ph meter but I didn't at the time (still don't).

I am at a stage where I am not at all committed to any one course of extraction method. It's all small scale experimental phase at this point. I've had some limited success with amalgamation. Whatever I decide to scale up to a production level I'm really wanting to keep it as simple as possible.

Cyanide-easy,simple,cheap, but if you get it wrong it's gonna break eggs. know what I'm saying?

Mercury- a little out dated this day in age. It has a place as long as the gold particle size isn't too large or too small. Potentially environmentally deleterious if it escapes its metallic phase and combines with something in the ore and goes water soluble organic compound mercury.

Chlorine- it works but it tough to tailor/ pretreat the ore to a condition where that chlorine doesn't get used up eating all the iron and base metals in sight, that and maintaining Ph for a hypochlorous state where its active but not off gassing.

Thiourea-short leach life. Don't know much about it really.

Iodine- not economically viable for treatment of raw ores

Bromine- like chlorine but more expensive and potentially more dangerous

That's where I am at. I feel kinda stuck. I don't know which direction to go on this.
 
Lou said:
Oh and as to thiourea...works great very fine gold. Better than cyanide. Easily recovered with zinc or borohydride. Of course one can always work with base hydrolysis and redissolve the sulfide in aqua regia, kill nitric, dilute and chill, filter and precipitate the gold with hydrazine salt. Much more expensive

Pregnant solutions may crystallize and are very orange red.

So how does one go about using thiourea on a raw ore? Is it a matter of buying a chemical and sprinkle sprinkle a la a little lime a little cyanide a little water? Or do you have to generate it ad hoc for usage centrifuges, filter presses etc? I know very little about its practical application leaching ore only that it seems to be short lived thus lessening concerns for environmental impacts.

I don't even know where to begin formulating a follow up question to the whole base hydrolysis. Way over my head.

My impression is that raw ore treatment with AR is a no go. Especially for my application, too expensive and too messy with all the base metals present in my partially decomposed oxide/sulfide quartz ore
 
To negate fools' gold you need to do a sample with AR, at least once, even though the preferred process may be different
 
Cyanide is more short-lived than thiourea. Short-lived is concentration and environment dependent anyway.
Chlorine in acidic conditions will not just oxidize sulfides but all
I only use thiourea for concentrated products or a solvent extractant strip. I have done tests on Pd, Pt, Au powders and watched it out perform cyanide time and time again.


Sounds to me that you really need to comminute, float, and then go after the concentrates if it's 1 opt.

You could easily get an electric motor, gearbox or big big flywheel for momentum, some 1" steel, break it into half a hexagon hard face it with manganese and make a chain/hammer mill to get it to fine powder separate from oversize high grade gold and go after the froth concentrate.

I have a 15 HP electric motor chain mill in production that's being made from AR400 steel. Want me to toll grind it? I also have a good size ball mill (think 12' long x 5.5' wide) and rod mill.

You need to get it ground up.
 
Lou said:
Cyanide is more short-lived than thiourea. Short-lived is concentration and environment dependent anyway.
Chlorine in acidic conditions will not just oxidize sulfides but all
I only use thiourea for concentrated products or a solvent extractant strip. I have done tests on Pd, Pt, Au powders and watched it out perform cyanide time and time again.


Sounds to me that you really need to comminute, float, and then go after the concentrates if it's 1 opt.

You could easily get an electric motor, gearbox or big big flywheel for momentum, some 1" steel, break it into half a hexagon hard face it with manganese and make a chain/hammer mill to get it to fine powder separate from oversize high grade gold and go after the froth concentrate.

I have a 15 HP electric motor chain mill in production that's being made from AR400 steel. Want me to toll grind it? I also have a good size ball mill (think 12' long x 5.5' wide) and rod mill.

You need to get it ground up.

Are you in Arizona? PM me?

Preliminary plans are for a medium Jaw crusher (0.5 tons / hour) and a medium-small rod / ball mill (preferably rod) still working on raising the capital for that.

Currently I can mill about 50lbs/ day to minus 20 mesh. Not production scale for the grade I am working.

I've been developing a relationship with TCB Metals in Phoenix area http://tcbinter.com to see about some initial testing and processing. They do a thiourea leach with big filter presses, computer controlled feedback loop ORP-Ph, 1 ton per hour, able to take raw ores - They got it figured out. It's nice to have that option available. The cost of their service does come at a moderate expense. I would like to develop an in house recovery option. Like everything else figuring it out one piece at a time learning up on the options so when the time comes I can do it.
 
Lino1406 said:
To negate fools' gold you need to do a sample with AR, at least once, even though the preferred process may be different

I don't understand what you mean by to negate fools gold?
Won't an AR leach dissolve all gold contained? Both free gold and gold locked up in sulfide matrices?
 
Lou said:
Cyanide is more short-lived than thiourea. Short-lived is concentration and environment dependent anyway.
Chlorine in acidic conditions will not just oxidize sulfides but all
I only use thiourea for concentrated products or a solvent extractant strip. I have done tests on Pd, Pt, Au powders and watched it out perform cyanide time and time again.


Sounds to me that you really need to comminute, float, and then go after the concentrates if it's 1 opt

Understood on the Chlorine. At less than pH 5 or thereabouts it begins to exist as a predominantly gaseous product, not the hypochlorous state you want for precious metals leaching. Low pH conditions and it attacks base metals (most troublesome of which is iron).

Froth flotation. I know it from industry. I've heard a lot of hobbyists/ small scale-er's talk about it. Know anyone who's done/ doing it? Something reasonably efficient for a small scale operator? 300-500lbs of raw material an hour?
 
You need to get it finer than -20.

Once you've done that, probably send deano a PM.

There are various agents that can be tested out in a lab for frothing and I can even do so for you.
 
Sorry, I thought everyone knows what is fools' gold. Of course it does not contain gold, but glitters
 

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I know what pyrites are. AR will digest pyrites. And most everything else except silica. Pyrites in the material I have are all oxidized away to geothite and limonite. I don't understand where you're heading. AR is almost never any good for extractive metallurgy of raw ores.
 
RenoChris made the single best post ever about fools gold.

Hit it with a hammer and it shatters. Gold deforms.
 
If you don't want to take risks with chemicals, you could try the method used by the ancients .
Heat your rock in a barbecue to release any gold from sulfides, plunge it into bucket of cold water mixed with vinegar. The quartz will break up and can be turned to sand with your fingers. Then whizz it when dry in a food processor to separate the various metals by density. No harmful chemicals or intensive work involved.
 
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