# leaching techniques



## Strikeitrich (Nov 29, 2011)

Hi all,
Is there anyone who can give me some helpful techniques for leaching gold out of ore?


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## jeneje (Nov 29, 2011)

You have already asked this once please do not post in different threads, there are many different techniques for different types of materials. You will want to first download hokes books to start and continue buy researching the type of material you want to process here with the search function at the top right corner on this page. To help you - you need to first learn the basices. This is all in the hokes book. Hope this points you in the right direction. Welcome to the board.

Ken


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## Reno Chris (Nov 29, 2011)

Hoke's book, while full of great information and very practical ways of doing things, really does not address itself to the leaching of ores. Still its well worth reading for any new comer. 

There is no single monolithic way of leaching all ores. Ores differ considerably and what might work for one, may not work for another. That is why there are many different treatments. Get your ore assayed to find out what you really have and then you can think about potential treatments - not all of which are leach related. 

Its almost like asking what kind of tires should I buy for my car when none of us has any idea what type of vehicle we are talking about.


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## Geo (Nov 30, 2011)

Reno Chris said:


> Its almost like asking what kind of tires should I buy for my car when none of us has any idea what type of vehicle we are talking about.



ou,ou i know.
round ones.

im sorry.i just couldnt help myself. :lol:


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## Richard36 (Jan 13, 2012)

T6 and CLS are relatively simple to use. 
I would recommend reading up on how to use those chemicals.

I've done my homework, and know how to use both.
After you've read up on how to use T6 and CLS, if you still have questions, I'll answer them.

T6 works on most ores, Oxide and Sulfide.
CLS was designed primarily for use on Sulfides, and will work on almost all ores, Oxide and Sulfide.

Sincerely, Rick. "The Rock Man".


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## solarsmith (Jan 13, 2012)

the many assays iv had done on my ore all show that Iv got 8 to 9 percent iron
so before I will leach for pms I will removing any thing that might be a problem later. fortunatly iron responds to magnets and I can magneticly remove the iron with a home made magnetic sluce box. I will ad a picture soon. An assay is the most important thing some one with ore can have done, not just a gold and silver assey, but a 30 or more element XRF test too.
I hope to see more here about this topic (ore leaching)
Bryan In Denver Colorado 303 503 4799


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## Traveller11 (May 7, 2012)

I have a placer ore with micron gold in it that seems to defy any gravity method I attempt to use on it, although I have not tried a centrifuge on it, yet. I am interested in using the acid/clorox leach on it but, there is just enough iron, in the form of magnetite and hematite, to interfere with this leach.

Is there any way to remove the iron chemically? Or, outside of cyanide, is there a leach that will dissolve only the gold and not touch the iron?


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## Geo (May 7, 2012)

Traveller11 said:


> I have a placer ore with micron gold in it that seems to defy any gravity method I attempt to use on it, although I have not tried a centrifuge on it, yet. I am interested in using the acid/clorox leach on it but, there is just enough iron, in the form of magnetite and hematite, to interfere with this leach.
> 
> Is there any way to remove the iron chemically? Or, outside of cyanide, is there a leach that will dissolve only the gold and not touch the iron?



did you roast the ore and try the magnet again? roasting will remove the sulfates and you should be able to remove the iron with hcl. try boiling a sample in hcl and see if you dont get a color change to the red side.


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## Traveller11 (May 7, 2012)

I thought roasting removed the sulphides.


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## Geo (May 7, 2012)

yes, i dont know the exact chemistry involved, but i believe it is emitted as sulfur dioxide. sulfur, sulfides, sulfates all react the same way when heated beyond the boiling point of sulfur. this could be faulty as it is what i was told by people who did it regularly. that doesnt make it right and im sure that if its wrong, someone will correct it.


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## butcher (May 8, 2012)

Iron sulfate is soluble (ferrous sulfate), sulfides are not, roasting can break down sulfides, sometimes free iron (powder from filing iron) in the roast can actually help to break down the sulfides in the roast, the gases can be toxic from ore arsenic and other deadly gases are possible, the finer you grind the ore the better, the ore should be roasted red hot and held there for about an hour, plenty of air exposure, the iron in ore can be magnetic and non magnetic, roasting can sometimes help to convert some of the non magnetic iron to magnetic iron, some ore may need lime and carbon from the fire to convert. it is not always as easy as it sounds, iron forms many compounds some like the hydroxides are almost impossible to dissolve in acids (if you can dissolve the gold from these no problem, but if they lock up the gold they would need to be converted to Iron for acid to attack).

Sulfide can be froth floated to concentrate.

Any time the values can be concentrated they should be.
Any time the gold or values can be removed by other means besides smelting or leaching it should be pursued.
Some ore would be better smelted than leached,

The ore can be a reducing or an oxidizing ore, this can be a clue to what chemical you may need to add to the ore to either oxidize or reduce the metals in the ore, you would also have to have an idea of what form these metals are, and what form you need them in for the acids to dissolve them, this way you may determine a chemical in the roast or in smelting is needed.

Some ore types they will add salt in the roast, to help dissolve the gold in the high heat, but adding salt to the wrong ore or too much can also make the gold volatile and it could also be found where it condensed a yellow liquid gold chloride on cooler surfaces around the roasting furnaces.

Leaching of ore with acids will not always work well or at all there are many different types of ore, some can actually neutralize the acid about as fast as it is added, also it can contain many types of metals besides iron, and these metals will need leached from the values, this is where leaches more specific for gold are a better choice like cyanide.

If the gold is free gold, and not invisible in the ore I would concentrate it with gravity or some other method, before trying a leach.

If you are going to leach the gold you should first get analysis of the ore, to determine the metals it contains and also the chemical makeup, then you have a better understanding of what may or may not work, or how to approach the problem.

I have only played with ore on a small scale, and have studied on it some, but the more I learn the more I find there is to all of this, and I also learn how much more I do not know about it, it is not that simple.

The black sands I say forget about trying to leach gold from them, pan the gold out of them, then if you wish make iron from the black sands (probably easier than getting the small amount of gold they may contain, the gold would be an impurity in the iron, so when the iron is forged check the slag in your blacksmith shop for value. this was kind of a joke but it is so close to the truth it is not funny.


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## Traveller11 (May 13, 2012)

butcher 
If I could pan the gold from this placer material, I would not be here asking questions about leaching. Did you not read the part about micron gold?


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## butcher (May 13, 2012)

Traveller11, I know you called it micron gold but from your discussion it sounded like this was free visible gold (placer gold), not invisible gold in ore, If I can see the gold with my eye's I can pan it no matter how small, if it is invisible in rock, and I had an assay to prove it was there then I would consider leaching the ore.


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## Traveller11 (May 14, 2012)

I'll put it this way. Almost everything from a deposit of black sand on the beach here will go through a 100 mesh screen and much of that will go through a 120 mesh screen. Yes, I could likely pan it, but then what? Pick it up with a snuffer bottle? At that rate, I would be a year putting together an ounce. Some of this gold is way smaller than 200 mesh.

There are no pickers in this material. We have tried sluices with all the fancy matting available. We could try a centrifuge, but those machines are ridiculously expensive, and you still end up with a concentrate of gold and black sand.

The best method I have devised is removing 90-95% of the magnetite and hematite with N52 neodymium magnets, leaving a concentrate of a low enough volume to make leaching economical.

The only thing standing in my way is removing the remaining iron prior to leaching with the acid/clorox leach.


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## Barren Realms 007 (May 14, 2012)

Traveller11 said:


> I'll put it this way. Almost everything from a deposit of black sand on the beach here will go through a 100 mesh screen and much of that will go through a 120 mesh screen. Yes, I could likely pan it, but then what? Pick it up with a snuffer bottle? At that rate, I would be a year putting together an ounce. Some of this gold is way smaller than 200 mesh.
> 
> There are no pickers in this material. We have tried sluices with all the fancy matting available. We could try a centrifuge, but those machines are ridiculously expensive, and you still end up with a concentrate of gold and black sand.
> 
> ...




This might help.

http://www.youtube.com/watch?v=bZaHmFsvnXE&feature=related


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## Traveller11 (May 14, 2012)

Do you know how much a Micron Mill Wave Table sells for?


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## butcher (May 15, 2012)

http://www.actionmining.com/Catalog.pdf
http://www.actionmining.com/


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## Traveller11 (May 15, 2012)

butcher said:


> http://www.actionmining.com/Catalog.pdf
> http://www.actionmining.com/



I don't think you caught the drift of my post. I already know the price of a Micron Mill Wave Table. I was asking the question rhetorically to emphasize the fact I am not prepared to shell out tens of thousands of dollars to process the low volumes of material I am speaking of.

That being said, is there no way to chemically remove iron, economically, from my concentrated placer material that I might leach the gold from it with the acid/clorox leach?


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## butcher (May 18, 2012)

Yes you can remove small amounts of iron, but to remove large amounts of black sand from a tiny amount of gold would cost in fuel, labor, chemicals and waste.

Smelting is also an option for concentrated gold with small amounts of black sand.

But the key word here is concentrating, basically separating the non gold materials and getting the gold materials as free from non gold as possible.

Miners usually can build what they need if they cannot afford to buy them, if you are handy you can build anything to may need to separate or to concentrate your gold.

Again if you’re not talking about a whole beach of sand a pan will work, if you are doing large quantity's then you will need to concentrate with other means.

You keep saying this gold is so fine you cannot pan it, are you sure it is not pyrite you’re seeing or trying to recover it is much lighter than the black sand and will float out easily, gold has a density much higher than the black sand and will stay in the pan when you pan out everything else, even minute pieces of gold weigh much more than the 2” and smaller rock, if fine gold try’s to float clean your pan, a drop or two of dish soap also helps.

This may give you some ideas:

http://www.google.com/search?hl=en&source=hp&q=gold+concentrator&gbv=2&oq=gold+concentrator&aq=f&aqi=g8g-m2&aql=&gs_l=hp.3..0l8j0i5l2.1437.8938.0.10047.19.14.1.4.4.0.79.985.14.14.0...0.0.GF7-6bgO_YI

Chinese were very good at panning gold, in this area Chinese miners sent billions of dollars in gold back to china, just from re-working the tailings the white miners let pass through their process. And these miners were capturing the very fine gold, maybe you need some Chinese to teach you to pan, or you can hire a few to pan for you. :lol:


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## Traveller11 (May 19, 2012)

butcher said:


> Yes you can remove small amounts of iron, but to remove large amounts of black sand from a tiny amount of gold would cost in fuel, labor, chemicals and waste.
> 
> Smelting is also an option for concentrated gold with small amounts of black sand.
> 
> ...




I'll try to explain this again. Yes, you can pan this material, if you have the patience. I don't. I know people that pan this material. One fellow has been out doing it every weekend for the last few months. It is a painstaking process, much of the ultrafine gold is lost and I think he is still working on his first ounce.

Concentrating this material is not difficult. The ocean has already done most of the work. Further concentration is done by screening. After that, a goodly portion of the magnetite and haematite can be removed with rare earth magnets BUT, this is tricky as, if one attempts to remove all of the black sand with magnets, gold particles will become "entrained" with the black sand and lost.

Do you see what I'm trying to say? I can reduce it to small, economically leachable volumes but, I must still deal with a small amount of black sand before the acid/clorox leach will work for me.


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## butcher (May 20, 2012)

Traveller11, 
I do understand, I have been working placer gold for years, I have also worked sand beds, it has always been a hobby for me, I make and use some mining equipment, nothing on a large scale, shaker tables, blue bowls, spiral wheels, classifiers, and dredges, and various other equipment, if your working large volumes of sand, and do not wish to pan, there is equipment you can make or buy, most all of this equipment comes down to the point i have been trying to get across to you, but in my view you are wanting some magic leach that works to remove gold without pretreatments like concentrating roasting and so on, there are some leaches that are specific to gold, but even these you would need to treat the ore, when gravity is your friend here, yes you can try to leach, but if the gold is free from the ore, I would use gravity to get the gold concentrated, if not totally separated from the sand and other materials, once concentrated very well smelting would be an option, leaching would be my last option and only then from a very concentrated gold material, with pretreatment, the leach first would focus on base metals, and then the values.

Mining supply houses have the equipment you need, I personally would not go out and buy equipment before I got gold, I get the gold then I add to my tools, for instance I would not go out and buy some big new dredge, I first would work my pan, (in fact many of my first pans were not store bought, I learned to pan gold using a hub cap from a truck, and even today I sometimes use a hub cap to pan gold, I would get some gold then take that money and build me a sluice box use that to get more gold then work up to building my dredge built from scrap metal, an old lawn mower and a scrap pump, later I upgraded the dredges I built, I have several now and still have no need to go buy a new dredge, Yes I would love to have one of those big Keene dredges, and a air compressor, but unless It would pay for itself better than my homemade tools do, I will just keep the gold I have now, and not trade it for a shiny new dredge, that may not pay for itself.

I have my ideas, of how to recover gold, you have yours, I have tried to share my ideas with you, you do not seem to like the way I see this, you seem want to hear what you want to hear. I will not change my views just to say what you wish to hear.

I could most likely work the sand you have with screens, a drain pipes, and a pan, and a few hand tools, if the gold was there I could, scale up the equipment, either made or bought from the gold recovered.

You can run a lot of sand through long toms, and with miners moss and good riffles, and side boxes you can collect almost all of the gold that went into it.
If you set up the equipment right you could capture more fine gold than the old miners did when they used mercury coated copper plate’s, and some of the modern separators can separate the sand from the gold (no matter what size better than some of the best hand gold panner’s).



Gravel companies in my area, sell tons of the black sand they ship it to china, this black sand has the majority of the gold removed, but still contains considerable values, if you are working large beaches, with good values maybe you can mine them in a similar fashion, with large equipment, selling the lighter sand for cement, collecting some gold and ship tons of black sand to china, personally I hate to see our valuable raw materials go to china.

I see many miners in my area go out and buy High dollar equipment, you they do move more material and do get some gold, but it has not paid for their equipment, so in my mind they are gold in the whole, spending more gold than they have mined, I do not get as much gold, but my gold is all profit, my equipment is paid for, and now I can buy larger equipment if I wished.

If your stuck on the idea of leaching, I have never tried these but action mining sell some leaches, you could try them (they may or may not be something like sodium thiosulfate), I am not sure of the name but it seems to be CL6 or something like that, give the girl who works there a call she can help you better than I seem to be able to, she may have the equipment or the leach you need at a price you are willing to pay.


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## renatomerino (Jun 10, 2012)

butcher said:


> Traveller11,
> I do understand, I have been working placer gold for years, I have also worked sand beds, it has always been a hobby for me, I make and use some mining equipment, nothing on a large scale, shaker tables, blue bowls, spiral wheels, classifiers, and dredges, and various other equipment, if your working large volumes of sand, and do not wish to pan, there is equipment you can make or buy, most all of this equipment comes down to the point i have been trying to get across to you, but in my view you are wanting some magic leach that works to remove gold without pretreatments like concentrating roasting and so on, there are some leaches that are specific to gold, but even these you would need to treat the ore, when gravity is your friend here, yes you can try to leach, but if the gold is free from the ore, I would use gravity to get the gold concentrated, if not totally separated from the sand and other materials, once concentrated very well smelting would be an option, leaching would be my last option and only then from a very concentrated gold material, with pretreatment, the leach first would focus on base metals, and then the values.
> 
> Mining supply houses have the equipment you need, I personally would not go out and buy equipment before I got gold, I get the gold then I add to my tools, for instance I would not go out and buy some big new dredge, I first would work my pan, (in fact many of my first pans were not store bought, I learned to pan gold using a hub cap from a truck, and even today I sometimes use a hub cap to pan gold, I would get some gold then take that money and build me a sluice box use that to get more gold then work up to building my dredge built from scrap metal, an old lawn mower and a scrap pump, later I upgraded the dredges I built, I have several now and still have no need to go buy a new dredge, Yes I would love to have one of those big Keene dredges, and a air compressor, but unless It would pay for itself better than my homemade tools do, I will just keep the gold I have now, and not trade it for a shiny new dredge, that may not pay for itself.
> ...


butcher:
I think these exchanges of ideas enrich this forum.
Each post reflects, criteria, experience, knowledge and aspirations.
In the previous message, you must specify that the leaching is used to recover a golden type whose size can not be processed by gravimetric method and is not presented in washed material.


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## butcher (Jun 14, 2012)

renatomerino, 

You are correct, leaching of gold should be, or may be the only option to recover the values from some ore, where density separation is not an option, where the gold may be so fine or chemically combined in the ore that separation using gravity would not work.



I feel leaching would work best for Highly concentrated material, where the gold or precious metal has been separated from other material as much as possible, much also would depend on the source material, and if the leach can be done selectively, or the other metals or reactions with the ore (chemistry) will not interfere with the process, or would make it so expensive as to be unprofitable, much would also depend on the material or ore, and the pretreatments, and the leach solution chosen.

Leaching ore where you cannot separate the gold by density, the gold would still normally need pretreatment, and to be concentrated if possible (like in froth floatation of sulfide ore), usually the ore pretreated to improve leaching (like in roasting process and sometimes chemical are used in this process), and the leach is usually chosen for its selectivity or how it would act chemically with the ore, sometimes the leach can actually be a way to concentrate the values by leaching some other mineral or metals from the ore.

Placer gold is free gold, and can be separated by density, but to try and leach barrels of black sand for a few grains of gold does not make sense to me, if this is sands and it was gold and not pyrite, the sands can be classified and the gold separated using density and the proper tools and technique, at least this is my opinion as a hobby miner.


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## mechanikat (Dec 9, 2012)

I am getting some interesting results on small batchs using 
Iron Out. No real conclusions yet. 















u
ot


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## butcher (Dec 13, 2012)

mechanikat, 
keep us posted when you get real conclusion, on those interesting results.


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## Ali (Jan 15, 2013)

It makes sense Conducting leaching on micron gold particles as it is hard to collect them by gravity separation methods,if you have big quantity-low grade ore you better try heap leaching with Sodium cyanide(if it's permitted where you live),it could reach up to 85% recovery if conducted perfectly.if you got small quantity-high grade try CIP or CIL leaching (look for "agitation tanks leaching" on the web),you must also know that larger gold particles(+ 70 mesh)need much time to be totally leached,base metals consumes the cyanide,increasing the solution concentration can help.


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