Guest flintgreasewood

"flour Gold" Recovery

44 posts in this topic

I have a miner friend who has come into an extensive placer deposit containing a very significant amount of flour gold...determined by fire assay.  So far he has been unable to come up with any method of recovery.   Amalgamation would probably do the trick but he won't use mercury and he is apparently unwilling to ship his cons to Texas to have cyanidation done.  Any ideas?

Coeur_D_Alene likes this

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What can I say? If you are not willing to do what is necessary to get the gold out, what are your other options? Acid leaching is worse than cyanide.

 

Hire 20 guys to hand pan the material a cupful at a time?

starvin likes this

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Environmentally speaking, acid leaching is worse and nastier than cyanide. When you add aqua regia to placer cons, lots of stuff goes into solution with the gold. Often the other stuff interferres with the recovery of the gold. Even if you do get the gold out, you end up with a nasty witches brew of acids and heavy metal toxic waste that is very expensive to get rid of.

Coeur_D_Alene likes this

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Steve,

    I am not privy to that information..at least not at this point in time.  My friend has grown accustomed to big gold finds all his mining career and this find makes him excited.

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Part of it depends on what is meant by "flour" which is not really a scientific term. Stuff a lot smaller than 100 mesh starts getting hard to recover using gravity methods.

 

The other thing is that fire assay is not a good way to test placer deposits, it commonly yields numbers that cannot be achieved in any gravity circuit as it recovers gold not recovered in any placer process.

 

Options also take into consideration how much he has - 10 pounds a day or 10000 pounds a day or whatever.

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The reason I asked is I always wondered what values cons would have to make it worth shipping them to a smelter. And if anyone can actually smelt normal magnetite infested cons economically. I never hear about it being done so I assume it is not economically feasible.

If any huge bucketline mine in California had put the cons in a pile for 100 years the pile would be the size of a small mountain and worth a fortune now I would think. If I had ever mined at Moore Creek I was going to stockpile the cons. I mean, why not? You already have them. Yet in most cases I think fortunes have been discarded over the years.

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There are dozrns of proper leaches for just about any ore BUT sulfides/sulfites do complex the process. Electrowhinng,bromides amalgamation,cyanide safest and easiest or nasty ol' mercury too. Volume,worth per cu.yd.and deep pockets are the predication factor to any recovery op. John

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There are some important answers that I would want to know when asking questions about recovery to refining methods; that are available, practicle and economical:

Where is the Gold? Placer - depth, overburden type & size. Hardrock - type

What size is the gold - mesh range. Don't use descriptive terms that are not well defined.

What is the shape of the gold? - flat, round, balled, tubular, flake (descriptive terms ok here)

What is the color of the gold?

Is the Gold free gold or is it tied up in or with other minerals or metals?

Ore: Size of the ore body? acessability?

How many oz. of gold per head ore ton (2,000 lbs.). Is this uniform throught the ore body?

Has the ore been weathered? water only, air only, moisture with freezing, underground?

Are there other precious metals in the ore

Methods: How has a/the concentrate been made? dry? wet? Equipment used?

Has the rock/ore been crushed, ground, hammered, pulverized, smeared, floated, etc.

And finally: Who is the owner?

How much will the owner share of the gold recovered if they contracted out for any, to all mining processes or operations from the start to dore bars or gold buttons.

Most all gold is recoverable from nature. The question is: how much are you willing to pay to get it?

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So ya wanna float--just build a good ol'school floatation cell,get some eucalyptus oil and a blower and your in biz-sink,swim or float it can be done-John

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Small gold does float under certain conditions, but it does not float well - not like sulfides. Floating gold using flotation methods has been studied and tested by people who understand flotation, bubble angles and the whole 9 yards of the science of flotation and no one does this commercially because it works very poorly.  The gold does not stay attached to the bubble in the froth of a flotation cell.

Flotation as a method of recovering metallic gold is a poor way to go. Flotation works great as way to recover sulfides, including sulfides that have microscopic gold encased in them, but it does not work for recovering fine, free gold.

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Does anyone have any knowledge of using nascent chlorine to separate free gold into gold chloride?

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Hense the eucalyptis oils usage in floatation is essential. Millions of ounces recovered on American flats just below Virginia city.John

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Don't take my word for it.

 

Geo - I can find you web pages that believe the world is flat, cold fusion is real and space aliens are running our government. Just because a web page mentions it, that does not mean flotation of free gold is a commercially viable process There are loads of gold mines all across the world. Many use flotation to recover sulfides. I doubt there is a single one that uses floatation to recover free gold as their normal ore processing method. Many tests have been done, and yes gold can be floated under certain special conditions, but there are loads of difficulties that render it impractical on a production basis. I will do up something explaining why flotation of free gold is impractical with more details about the why of things for the ICMJ in the next few months.

 

John - I am quite familiar with the mill in American Canyon and no, they did not float free gold. Yes, they did float sulfides, but that's a different thing. Did you know that the BLM just made a formal decision to tear down the old concrete structure of that mill?

 

Flintgreasewood - Chlorine was used in a number of mines before the use of cyanide was perfected in the 1890s. It is used in a few rare cases still. It is an acidic process and most often results in a lot of toxic waste which is why its little used today. Free chlorine is nasty stuff, but It does work.

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Setting aside the Chemical Technicalities for a moment, isn't this supposedly a Placer Deposit ? And how many people generally use Fire Assay to sample a Placer Deposit ? In fact, hasn't it been said by many an experienced Geologist NOT to rely on Fire Assay to sample Placer Gold ? In which case, why not just run it through a WashPlant and get as much as possible ? If there is concern that you are losing significant amounts of fine or flour Gold, then run the Sluice Cons through a Concentrator as suggested by Robert above - either a Knelson or an Icon. If you decide to go to the trouble / expense of setting up a more Technical " Circuit " and can get control of your Water through a Re-Circulating System, Floculants can be added to the water itself which apparently encourages the " Floating " Gold to sink and subsequently be captured / recovered. 

 

Any of these non-standard Recovery methods require a lot of testing to achieve the ideal balance of Chemical vs Metal to reach the desired result of recovering more Gold. There would have to be a significant amount of Gold being lost in those Tails though to justify setting up anything more complicated than a standard Gravity system, particularly if it involves Chemical extraction. I don't think any of us ever expect to recover much more than 90 + % anyway. 

 

Flint - If it's an extensive Deposit that justifies the expense and your friend has been unable to come up with any method of recovery, then it looks like he has no choice other than to do some serious Bulk Sampling through a purpose-built Pilot Plant under the guidance of a good Metallurgist. Best of luck with it and let us know the outcome in the event one of us experiences a similar problem.                 

gmeyer likes this

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the popandson sluice developed a few years back was supposed to catch up to ... or down to 350 mesh, there is a complete treatise on this concept over at the Alaska gold forum. i use a form of this for oregon beach gold which typically runs 80 mesh in size

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Chris- Modern technology has improved the process of using chlorine as a method to dissolve gold. Resin technologies have virtually eliminated the early problems associated with using chlorine as a lixiviant and the problems of waste bi-products. There is a company that has developed a proprietary method to extract gold which starts with salt, water and muriatic acid, all available at your local home depot. The process reuses the solution over and over again, the gold and PGM's are precipitated from the solution with that proprietary resin I mentioned. Any heavy metals dissolved in the solution ie: lead, etc. are removed via resins and the resulting solution is either reused or discarded as reclaimed water....

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Chris-  Maybe in the old days chlorine production resulted in a lot of toxic waste, but modern electrochemical technologies produce chlorine with little toxic byproduct. True, free chlorine is nasty but modern instrumentation can eliminate free chlorine by proper feed ratio's.

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