# Small Scale Treatment of PM Sulfide Ores



## Reno Chris

There is no one universal way of treating sulfide rich precious metal ores - in the mineral kingdom there are all sorts of complex minerals which contain, in addition to gold or silver, complex combinations of lead, zinc, copper, iron, nickel, manganese, palladium, mercury, antimony, arsenic and others. In addition to sulfur, one may also have ores with selenium, tellurium, and others. Gangue minerals are not just quartz and calcite, but may include a whole host of fluorides, oxides, sulfates, chlorides, silicates, etc. The point is that sulfide ores can be highly variable.
You can see that with sulfide ores, there are a million and one possibilities and while some types can be treated similarly, there are many different categories or types. There can never be a one size fits all approach. We can all wish for rich free gold ore! With that stuff, you just crush it up, pan it out and melt to make a button (or refine it if you like). But sulfides are another story. You need to convert whatever metals you have from mineral to metal, and do it without making a big mess, and without a big stink of sulfur dioxide and smoke to offend your neighbors, either. This is not necessarily easy. Then once converted to a metallic state, you must still separate the precious metals from the base metals. This is why the old timers had such difficulty with these ores and in many places simply gave up when the mines worked their way down to the sulfides. Rebellious or refractory ores they were called. 
I have about 200+ pounds (roughly 100kg) of rich silver gold ore that runs roughly 3 ounces per ton of gold and 70 ounces of silver. On that basis, my 200 pounds should contain about 0.3 ounces of gold and 7 ounces of silver - but I know that I won't get 100% recovery. There is also considerable iron, zinc and lead present, with some minor copper and very small amounts Antimony and Arsenic. All these elements are in the form of sulfides and complex sulfides (except the gold which is mostly free in tiny particles). I am not kidding myself that this is some money making scheme. It's a demonstration project to prove I can do this - though I will make a few bucks, just not much when you consider the time invested. The output of PMs will far exceed the cost of reagents and fuel, but I figure I will be getting less than 50 cents an hour for my time and one can hardly consider that as a way to make good money. I will have expensive equipment in use from crushers to furnaces to lab ware and acids. If I could buy a shaker table I could run the cost up by a few thousand, but I just can't justify that expenditure at this point. 
This is going to take some months to accomplish, as I will only be working on it off and on. I will take photos as things as they progress and share them here. My goal is to recover 10 to 15 grams of gold, 7 to 10 ounces of silver, minor copper (perhaps a few ounces) and a number of pounds of lead (the lead will be used to cast bullets). I may also attempt to recycle the zinc and copper I consume in the Parkes and silver cementation steps. Disclaimer - this is not intended as a full "how to" type of lesson with all the process details and necessary safety precautions clearly spelled out. I am sharing my efforts with the forum so you can see what is involved. If you attempt something like this yourself, you will need to possess the necessary mineral processing expertise on your own and understand all the dangers involved and know enough on your own to take all the necessary safety precautions. I am not offering to serve as anyone's consultant. A good description of the steps I will use are as follows:
*1. Crush the Rock.*
The rock cannot be processed as large chunks and cobbles - the form it is in now. It must be crushed to a powder to process. I have 2 crushers and will take the ore down to minus 20 mesh. Yet even before it can even be run through my crushers, I will need to break down the larger pieces by hand with a 2 pound hammer. I will have a dust collection system for the crusher operation which I will show (it will use a shop vac unit I have).
*2. Reduce the bulk of the ore. *
My 200 pounds of ore is a lot of rock to deal with. I will concentrate it down to the heavy components. Sulfides are generally dense minerals and gold is as well, so I will concentrate using a specially made sluice system. I wish I could use a shaker table, but these are several thousand dollars to purchase, an amount much more than I want to spend on this project. Yep, I will lose some, but I do not have infinite monetary resources. The ore has a 5 to 10 percent sulfide content, so I expect about 10 to 20 pounds of sulfide concentrate. Dealing with 10 to 20 pounds is a lot easier than 200 pounds. There will be some loss of values in this operation - but I accept this because although the method is less than optimal, it's the best I can put together. 
*3. Perform a series of giant fire assay fusions. *
The sulfides contain some galena (lead sulfide) but not enough lead to serve as collector for a full fire assay on that material alone, so I will add some other galena from another source (which also contains some good silver, but very little gold) and some Litharge (plus a bit of charcoal to help reduce the litharge). I will add a good amount of sodium carbonate and borax to form a flux. I will perhaps, also add some crushed glass as well to make sure there is enough silica to form a decent slag cover on the molten sulfide matte and maybe even a little crushed fluorite as well. The old assay trick of using scrap iron (normally nails) to reduce the molten galena will be used. THe formula is: PbS + Fe = FeS + Pb The reaction is driven because Fe is a more chemically active metal than lead (silver and copper are also displaced as they are less active than iron). I will carefully stir the whole molten mass with an iron rod (while the crucible is still secure within the furnace to be safe). The lead should capture the PMs, and when I pour the whole mass into a cone mold, I should get three products - a slag glass, a sulfide matte of mostly iron sulfides, and a lead button. I will use a large crucible and hope to process around 3+ kg of total material (flux + scrap iron + extra galena + sulfide ore concentrates) in each charge, with resulting a lead button of roughly around 1 to 1.25 Kg in size each time. 
The assay fusion will be done with a propane furnace out in the desert, in a fire safe location where odors and smoke not will harm or offend anyone. I also will use a mask with a HEPA filter to make sure I do not breathe any hazardous smoke. It may take 4 to 6 or so charges and pours to process all the concentrates from step 2. The lead will be retained and saved for step 4. 
*4. Perform a Parkes Process capture of the copper, gold and silver. *
On completion of the assay like fusion reduction process, I should have 5 to 8 Kg of gold, silver and copper bearing lead, which I will melt and mix with a couple pounds of zinc and stir. I will not take the mix up to a high temperature to try to dross out the copper, I will just collect the copper with the zinc and separate it later (there should not be much copper anyway). I read a thread on this forum where a member used a motor to create stirring for the necessary surface contact for the migration of the PMs and copper into the zinc. I will just stir for a time by hand with an iron rod. At the conclusion, I will pour off the material into a cone mold and after separation, I should have a low PM lead metal suitable for bullets and a few pounds of PM bearing zinc alloy. 
*5. Part the zinc from the gold, silver and copper with Hydrochloric Acid*
It may be that for use of Hydrochloric, inquarting may be necessary, but I will try without doing so first. When complete, I should have zinc in solution and the copper, gold and silver as an insoluble black powder. I will wash the powder well with warm water. I may attempt recovering the zinc by electrolytic methods - I should be able to get most of the zinc out.
*6. Part the gold and silver with nitric acid *
The silver and any small amounts of copper present will be soluble in plain nitric, and I will cement out the silver with metallic copper, then recover all the copper electrolyticly. I will then pour the silver into a fairly pure button and the gold and final nitric insoluble materials into their own button and at that point the final extraction process will be complete. The gold will not be .999, but it should be maybe 90+ which will be good enough for my purposes.


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## Irons

I took a tour of the Comstock many Years ago. One of the features was a pothole in the floor of the tunnel where an enormous amount of Gold and Silver had settled. The chunk of Ore that I took for a souvenir was a soft Talc with finely dispersed Pyrite. Never did process it, though.


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## blueduck

is -20 mesh small enough particles? I would think that even smaller particles would be easier to extract from, something closer to the -200 mesh size coming out of a ball mill or rod mill, both not as hard to build as one might think, and if you have enough ore, i wager you could talk someone who has a smaller ball mill sitting, to make a run or two for your testing.... 


William
Idaho


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## Reno Chris

Remember that -20 means that all of the ore is less than 20, but the majority of the ore will be maybe 100 mesh, with plenty being smaller. 

-200 mesh means all the ore is smaller than 200 mesh, with probably lots being around 400 mesh. There is such a thing as being too small, rendering the ore into a clay like state that is hard to treat - even if you are leaching with cyanide. One of the reasons stamp mills are no longer used to crush ore is that they made too much slime - that actually reduced recovery. 

So for what I am doing - recovery by gravity only - yes, 100% minus 20 mesh is about right.

Chris


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## solarsmith

your crushing milling goal should be 80% passing -200 I have made a ball mill that can do about 300 lbs an hr. since you have a sufide type ore you should be looking at processing via a floatation cell or column . I will not try to convince you as to method but id you look up someing caled the (75 ways of gold concentrating) your answer will almost certainly be there. Its the best info on methodes for finding grind size for each way od slucing or floating ore. good luck Bryan in denver [email protected]


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## DarkspARCS

Chris...

I reviewed some simple techniques small mining operators were using in poorer countries that may assist in your thinking on the sluice type you build.

It consists of a long wooden sluice placed at about a 10 degree angle that was fitted with tight nit wool shag carpeting. The miners would ground their ore to a fine powder then run a moderate flow of water down the sluice, mixed with the fine powder. the heavier metallic particulates would sink into the carpeting while the lighter minerals would was away. They'd let the silt flow out then take the carpeting up from the sluice and place it into a tub of water then basically wash the carpet in it, capturing all of the heavier metallic particles and then panning it. perhaps that may help...

Something I did awhile back that I've been recently pondering on is another possibility, IDK though perhaps you can try this and see if the results turn out like I suspect they did for me. I powdered my ore then set it to slow roast for about 2 hours at roughly 300 F. - mixing the contents every now and again then placing the contents into a warmed coffee pot then shocking it with muriatic. the greyish/ silverish material that began floating on the surface of the muriatic after it got through sputtering and steaming appeared to be a lead/ silver concentrate with gold flecks within it... as the image below shows in some small detail. I didn't have a chance to continue the experiment however...


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## torscot

Richard,

I tried a similar process to the muriatic bath you used, but on an arsinide type silver ore. I experimented with this to remove the calcite from the ore before treating it with nitric to remove the silver. It totally flopped and I have never bothered with this again. All I did was pollute this ore with chlorides making it difficult to treat with nitric acid. Win some lose some. Here's the similarity to yours. The frothing, boiling action of the muritac did float to the top the same silver "scum" . I collected just over gram of this from the surface of my bucket, washed and cleaned it. It dissolved in nitric, then immediately turned to silver chloride. So yes, you have floated some silver to the top. Totally inefficient for recovery. But, now you know it's there.

I am following this thread very carefully, as I have just brought home from Northern Quebec a few hundred pounds of sulphide type gold ore. So, this one's really got my attention. Hope this info on your silver froth helps.

Rob.


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## DarkspARCS

Thanks for the validation on your result torscot as it comparatively related to mine. I never thought to follow through with this though because at the time I was involved with a metallurgist who has a fairly equipped lab. He and I went our separate ways when i'd discovered he'd been fudging every ore test we'd done so that he could go back when i wasnt around to retrieve the lost PM/ PGM values from his firebrick walls and used cupels. he'd purposely overfire our tests with them for the most part failing to provide a result or if one appeared it was relatively minute compared to what the filtration promised... point in case look at the coloration on this cupel and understand that the reason why it's bright red surrounding the test reslt button is that a majority of the valued sank into the cupel material with the lead.




It really sucks when you're sitting on a substantially life changing property and all you want is for someone to actually be honest enough to help you develop it into that life changing result...

If you're truly into processing the gold sulphide ores that you say you are from what you've managed to collect from Northern Quebec i'd like to invite you to consider taking a trip down here to Las Vegas and We can spend some time putting our heads together on some rather high value ore types I'm absolutely positive you will become a giddy as the kid in a candy shop over...

Review this forum for a rather comprehensive look at exactly what it is I'm talking about... Cheers!

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=44&t=8709


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## 10wt_Percent

informative review of all things pyrometallurgical as relates to silver ores and the liberation of silver contained therein.

(there's a bit of corruption here and there .. machine translation artifacts)
well worth the read nevertheless 

http://archive.org/stream/roastingofgoldsi00ksrich/roastingofgoldsi00ksrich_djvu.txt 

and thanks to the OP for their insightful treatment on this topic (as well).


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## Richard NL

10wt_Percent said:


> (there's a bit of corruption here and there .. machine translation artifacts)


Maybe, this is better one to read. http://tinyurl.com/krloxbv

Best regards,
Richard.


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## kurtak

Just wanted to say I found this to be an interesting thread though I don't work with any ores any more(& haven't for a long time) but I do hope to again in the future so have been keeping an eye on this thread & hope more will be added as time goes on

Kurt


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## nh6886

Chris,

I'm with Kurt on this. I found the idea very interesting and look forward to reading about your progress.

Thanks for sharing,
John


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## Richard36

DarkspARCS said:


> ... point in case look at the coloration on this cupel and understand that the reason why it's bright red surrounding the test reslt button is that a majority of the valued sank into the cupel material with the lead.




If the resulting lead prill from the preliminary assay fusion were scorified to remove the impurities as it should have been, then there wold not be any precious metal loss to the cupel, and neither would the cupel be that color, nor would it have a dark base metal contamination ring, which this cupel definitely does have.

As an assayer I know that much, and can definitely tell that the lead prill was not scorfied before cupeling it to recover the precious metal values contained within it that were recovered from the ore in the fusion process. 

The contamination is copper that caused the color impartation to the cupel, 
and being that you and I are familiar with your ore, we know that to be an absolute if it were not removed before the cupeling process.

Give me a call and I'll privately share some leaching knowledge with you.


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## nh6886

Chris,

I can't believe it's been 2 years since I read this. I just wanted to ask if you had made any progress on your project?

All the best,
John


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## SnowmanHimalaya

I'm having similar problem and thinking about making small shaker table with use of laboratory orbital shaker like this one https://www.thermofisher.com/order/catalog/product/SHKE3000

not sure about what kind of platform to put on top of it.
thanks


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## Reno Chris

I cant believe that its been that long - I've made more plans and done only a little. toward moving this to reality.

I really need to work on this, hopefully when the weather here improves.

Also, I now plan on doing a full Youtube video of the entire process.


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## nh6886

Thanks for the update Chris,

I very much look forward to seeing that. If I were closer I would love to offer some free labor to your project.  

All the best,
John


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## kurtak

Reno Chris said:


> I cant believe that its been that long - I've made more plans and done only a little. toward moving this to reality.
> 
> I really need to work on this, hopefully when the weather here improves.
> 
> Also, I now plan on doing a full Youtube video of the entire process.



Hi Chris

Per the underlined - VERY much looking forward to the video 8) :!: 

Kurt


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## Reno Chris

Well, the first video, hopefully to be completed in the next couple months will be a 3 part "Rock to button" video on taking gold bearing quartz, breaking it up, crushing it, concentrating the free gold using a recirculating sluice and then taking the free gold concentrate and pouring a gold button. 

I can do all of the above at home. Part of the problem with the sulfide project is the smelting the sulfides down to lead containing the silver and gold. That has to be done at a remote site. I cant do that in my backyard as I'd have a dozen neighbors calling to complain about the smoke and sulfur odors. I will be kicking pounds of sulfur dioxide up into the air. So I will pretty much need to make a trip out to the middle of nowhere just for the purpose of doing the smelting part of the process.

I'll try to do these videos this summer and post notice here on this forum.


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## Iggy-poo

I know the place. On Rt. 50 in Nevada there's a sign pointing North and South at an intersection that says "Middle of Nowhere."


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## rhwhite67

Reno Chris African mining "secret": Gold PGMs including their sulfide forms and Diamonds all stick to vaseline petrolium Jelly. Make a simple sluice box with a plastic sheet layer in the bottom and coat it with a layer of vaseline. low angle slow water run your crushed ore over it. Re- run ore to make sure you got most all of it and the remove the plastic sheet scrape off the vaseline with a plastic paint scraper and thin the vaseline with acetone till watery consistancy the metals will drop to the bottom of your comtainer. de cant the fluid. put in a fireproof metal container ... stainless steel bowl. light on fire to burn of vaseline / acetone residue and process from there as you wish. Sounds wierd but it works well. Best of success in your efforts. Ron
Works on Sapphires also.


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## galenrog

rhwhite67 said:


> Reno Chris African mining "secret": Gold PGMs including their sulfide forms and Diamonds all stick to vaseline petrolium Jelly. Make a simple sluice box with a plastic sheet layer in the bottom and coat it with a layer of vaseline. low angle slow water run your crushed ore over it. Re- run ore to make sure you got most all of it and the remove the plastic sheet scrape off the vaseline with a plastic paint scraper and thin the vaseline with acetone till watery consistancy the metals will drop to the bottom of your comtainer. de cant the fluid. put in a fireproof metal container ... stainless steel bowl. light on fire to burn of vaseline / acetone residue and process from there as you wish. Sounds wierd but it works well. Best of success in your efforts. Ron
> Works on Sapphires also.



What purpose does this procedure have in treatment of sulfide ores? That is, after all, the purpose of this thread.


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## rhwhite67

The purpose of this vaseline sluice process set-up would be a way to simply and easily concentrate the sulfides from the crushed ore as after crushing it replacing the shaker table Chris said he would like to use here in @2 of he post with something just as effective and a whole lot less expensive and if he re-runs the material a couple of times he will capture virtually all of it. No matter what else you do to process sulfide ore the next step after crushing is concentration of the ore. Most large companies do this through flotation or as Chris mentioned a bank of tables. For us small guys on a budget this is a really good alternative that works well.
Ron


2. Reduce the bulk of the ore.
My 200 pounds of ore is a lot of rock to deal with. I will concentrate it down to the heavy components. Sulfides are generally dense minerals and gold is as well, so I will concentrate using a specially made sluice system. I wish I could use a shaker table, but these are several thousand dollars to purchase, an amount much more than I want to spend on this project. Yep, I will lose some, but I do not have infinite monetary resources. The ore has a 5 to 10 percent sulfide content, so I expect about 10 to 20 pounds of sulfide concentrate. Dealing with 10 to 20 pounds is a lot easier than 200 pounds. There will be some loss of values in this operation - but I accept this because although the method is less than optimal, it's the best I can put together.


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## ARMCO

Reno Chris said:


> I cant believe that its been that long - I've made more plans and done only a little. toward moving this to reality.
> 
> I really need to work on this, hopefully when the weather here improves.
> 
> Also, I now plan on doing a full Youtube video of the entire process.



I find this thread very interesting. Thank you. Also, what is your YouTube channel?

thanks again


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## Reno Chris

Here is a video I have done on Youtube on using a metal detector to find gold:
https://www.youtube.com/watch?v=sA2feW5XOFM

If you go there you can subscribe or sign up for my you tube channel. 

I have gathered now 166 pounds of free gold type gold ore, some of which has visible gold in the rock. This is 1/12th of a ton. In the next month or so, I am going to do a video on taking that gold ore rock all the way to a button of metallic gold.


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## ARMCO

Great, thanks. Wish you were in Alaska, I have a shaker table and hammer mill. Feel free to bring your ore up! ;-)


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## jcdog

Hello Chris,
One comment on your original plan to process a sulfide ore, don't use a HEPA filter for protection from fumes.
Fumes are vapors, which should go right through a HEPA filter. A canister type of filter with activated carbon would be best. 
JCDOG


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## FishmanTx

solarsmith said:


> your crushing milling goal should be 80% passing -200 I have made a ball mill that can do about 300 lbs an hr. since you have a sufide type ore you should be looking at processing via a floatation cell or column . I will not try to convince you as to method but id you look up someing caled the (75 ways of gold concentrating) your answer will almost certainly be there. Its the best info on methodes for finding grind size for each way od slucing or floating ore. good luck Bryan in denver [email protected]



Found that 75-Gold-Recovery-Methods book on Scribd:
https://www.scribd.com/document/281938063/75-Gold-Recovery-Methods

Also found a similar copy here with some of the same info "Fine Gold Recovery – Alternatives to Mercury and Cyanide Purpose of study":
https://www.researchgate.net/profil...urpose-of-study.pdf?origin=publication_detail


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## jobinyt

This is an old thread, but relevant to my situation. I've got perhaps 700-800 pounds of high grade sulfide ore, that I collected from abandoned silver prospect sites. More is available. Grinding a very small sample, acid, filter, and precipitation showed there is indeed a goodly amount of silver present - lead too - and likely small quantities of many of the other sulfides present (I expect manganese from one site), and perhaps a little gold.

No deserts where I live. I'm a bit nervous about working with sulfides - especially roasting. As an alternative to roasting, I've read, after a fine grind - say 200 minus - then, in a open air vat, if I add a small amount of fertilizer, keep damp, and stir occasionally, that naturally occurring bacteria will remove the sulfur - likely taking a few months to do so. Or perhaps, I'm overly concerned; roasting 800 pounds of 'galena' (not much rock in much of this stuff), in small batches, might not disturb my flora and neighbors?

I wonder though, if I've gone the bacteria route, should I proceed with concentration and refining, just as if the material has been roasted, or do I have something else - something that should be concentrated (no shaker table or flotation cell available) and refined in some specific fashion?


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## Deano

The easiest way to treat your ore is to see if you can find some one who will toll treat or purchase the ore based on assays.

If you cannot find such an outlet, reasons may be nothing such exists locally or your ore is too low a grade or too small a volume, then you are stuck with treating it yourself.

Roasting the ore will result in an amount of pollution that neither you or your neighbours will be able to believe. Totally forget this approach unless you enjoy being closely attended to by the EPA.

Sulfide ores suffer from sliming when milled, provided you are willing to suffer high sulphide losses then milling and concentration is feasible.

Keep in mind that your ore sources are likely very limited so you do not want to be putting a lot of money into concentration methods which will get little use.

Bacterial leaching is not quite as easy as you say, pH, bacteria starter type, moisture content and temperature are some of the conditions which are important.

The easiest way to treat sulfides is to jaw crush them to the tightest setting on the jaw crusher, usually around 10mm.

Pile the milled material on a thick sheet of black plastic with a drain pipe at the bottom to send any liquid to a holding pond.

A 20% NaOH solution is sprayed from the holding pond pump over the top of the heap for 6 hours and then the pump is stopped for 1 to 2 hours, then the cycle is repeated.

This sequence is continued until the sulfides have all been destroyed, depending on the temperature and the sulfide type this can take from weeks to months to achieve.

Deano


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## jobinyt

Thanks Deano,

First - you've confirmed all my worst fears - that's a good thing - keeps me out of trouble.

Second - Many reasons I'd like to do this myself - chief among them: 1) learning and curiosity 2) The material is from several general locations and quite a few veins. I haven't done a good job of keeping it separated. If I can learn how do this in small bulk samples in the remote area I'm working, I'll be able to determine what is worth more attention.

Third - a small crusher and leach system sounds good. I lack some critical knowledge though. I've done some acid extractions, and selectively precipitated lead and silver from them. I have no idea where to learn to selectively precipitate, individually, or in some group for later separation, the metals the pregnant caustic solution might contain. Where might I research this?


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## Deano

The base metals which are most likely to be dissolved in a caustic leach are lead and zinc, tin will also dissolve but it is likely that any tin levels will be low, any other metals will most likely be present at even lower levels. Keep in mind that cobalt will also dissolve in alkali solution and cobalt often accompanies copper rich ores.

There are many pH solubility charts for various metals on the internet but it is difficult to get a clean separation by precipitation.

If you are just wanting to drop out any dissolved metals then it is easiest to do so as a bulk lot, if you are only using small amounts of ore for testing then the value of these metals is low.

The above comments also apply to selective electrowinning of the various metals.

Deano


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## jobinyt

Perhaps I should plan 2 leaches:

A base leach to remove the base metals - much lead, plus who knows what else.

Then follow with some other leach to remove the silver - hopefully separated and reasonably pure from everything else. I've read a lab analysis summary of this stuff, but i don't know what the input the was; that is, pure vein material, some form of concentrate, or a more bulk sample. The acid/precipitation test I ran looked real good. I'm doing this for the fun and learning - a lot of the fun though will be seeing/producing/having hundreds of ounces of silver when I'm done.

You say though "difficult to get a clean separation by precipitation", so I wonder if I'm thinking entirely wrong about this. I'm looking/thinking I want a small scale, DIY, practical (meaning a safe and decent but not best recovery) means to refine my 700-800 pounds of ore - and perhaps double/triple that quantity later if it looks financially attractive.


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## fishaholic5

Deano said:


> The easiest way to treat sulfides is to jaw crush them to the tightest setting on the jaw crusher, usually around 10mm.
> 
> Pile the milled material on a thick sheet of black plastic with a drain pipe at the bottom to send any liquid to a holding pond.
> 
> A 20% NaOH solution is sprayed from the holding pond pump over the top of the heap for 6 hours and then the pump is stopped for 1 to 2 hours, then the cycle is repeated.
> 
> This sequence is continued until the sulfides have all been destroyed, depending on the temperature and the sulfide type this can take from weeks to months to achieve.
> 
> Deano



Thanks again, I have a growing quantity of massive Ruby Silver, Acanthite and PGM sulfides and Antimonides to find a processing method for. Would a flood and drain system on a relatively thin bed (>4") of finer milled material speed this up a little for a smaller operator? Heap leaching on site isn't an option. 
Breaking down the sulfides rather than roasting or trying to smelt directly sounds pretty good to me

Cheers Wal


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## Deano

If you are treating a small quantity of material then you most assuredly can do as you suggested with a thin bed system.

The crux of treatment is to subject the ore to alternating cycles of liquor and air, the method you use is limited only by your imagination.

Heating the leach solution will speed up the reaction with the sulfides, a small solar heating system will do a good job.

Note that all wetted components of the system must be stable in the presence of strong caustic solution.

Deano


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## fishaholic5

Thanks, I'll try a sample and test it at intervals. 
If I can remove the Antimony and Bismuth at the same time as converting the Sulfides would be good
Do the base metals drop as hydroxides/oxides in the leach reservoir as the Sodium Hydroxide becomes spent or is it necessary to add Sodium Hydroxide at regular intervals and maintain pH to keep them in solution?
I'm assuming any Silver Halides in the ore will be converted to Silver Oxide and I may put some of this into solution if the NaOH levels are too high.

Cheers Wal


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## Deano

Silver complexes are slightly soluble in caustic solution, you would need a vast amount of leach solution to have appreciable silver losses in solution.

If you are approaching saturation level for base metals in caustic solution then a drop in alkali level in that solution will cause the base metals to precipitate from solution.

Keep in mind that a drop in alkali level in the solution will also cause the solution to be less effective in sulfide breakdown, so you should keep a check on the alkali levels for this reason rather than for base metal saturation in the solution.

It would be an uncommon silver ore which has such high levels of alkali soluble base metals that they appreciably affected the breakdown of sulphides.

Deano


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## shrewdly

I have noticed several replies concerning thecorrect mesh sizes for extraction. The purpose of size reduction in ore processing is to reach a size range that gives you discrete particles of ore and of waste. Then a clean extraction can take place. Gravity separations are good down to anywhere from 60 to 100 mesh. Any smaller and hindered settling starts to take place or the slimes will just go with the flow (tables). Anything smaller than 100 esh is generally treated with froth flotation Sluice boxes can be highly effecient in recovering the heavy mineral being processed and can recover fine material but this is usually at the expense of larger sized material (nuggets).


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## Paul goldbugg

Has anybody heard of flexicone technology for sulfide ores. They have been around for a few years now. If what they claim is true it sure would seem to change some things for mining sulfide ores


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## Deano

Very few sellers of recovery systems actually show assays of ore from before and after processing.
Being able to show concentrate assays is meaningless unless a set of tailings assays shows that the process has high recovery rates.
I do not think that any gravity methodology will cause sleepless nights for the flotation designers.
Each technology has its area of best use, gravity whether natural or enhanced gives best results on coarser feeds.
Originally, straight gravity separation was the only option for concentration of sulfides.
Use of a table allowed cleaner separation of concentrates and treatment of finer sulfides.
Flotation meant that the entire mining industry changed to using this technology virtually overnight such was the improvement in recovery and selectivity.
If you really think that going back to any form of gravity method to replace flotation is a good idea then best of luck to you.
If I absolutely had to use a gravity method it would be wilfley or similar tables set up with sized feeds.
Very slow to process with but the recovery is good and the cons are clean.
Deano


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