Thiosulphate Dropped--Testing for PM?

Sorry, I wasn't sure what subject line to use with this. I'll post pics so you can see what I'm talking about.

First, we know we have gold and silver in our ore, as it's been tested by 3 different labs (one only tested for gold), but no one tested for the platinum group. We also know it's pretty much all (probably 95%) microscopic and must be collected using chemicals, as it's not free gold and can't be panned. The gold tested (depending on the ore sample) from 5 to 9 oz per ton, the silver approx 3-4.

My husband & I have been running test samples on 2 1/2 -3 lbs of ore, using 2 /12 to 3 gal of thiosulphate leach, then dropping with ferrous sulfate. Our understanding is, that if done correctly, thio leach will only capture gold, silver, and platinum groups. We've kept our ph between 9 and 9.2 until time to drop, so we know we're not losing or prematurely dropping any gold. Once we do the drop, we're getting about 150-180 ml of bright orange precipitant (measured prior to washing, right out of the separatory funnel, so a small amt of leach comes with it).

It's almost impossible to catch this stuff on a filter (even a very tight, good quality one) as the precipitant is incredibly fine and goes right through until the filter eventually clogs. So we've been draining it off into a heavy glass container, hitting it with 10% hcl to clean, then following up with water to wash again. We let it settle, pour as much fluid off as possible, then slowly cook to dry.

Here's our questions;
Does anyone have a better way of cleaning this product without losing it through a filter? Yes, we can repour the precipitant back through the filter once it clogs, but it's also so fine that it's almost impossible (once it totally dries) to scrape much off the filter. I suppose if we had 4 times the quantity at a time (and we will have once we start doing larger runs) we'll have a lot more on the filter, but that brings up another problem. The filter clogs somewhat fast and by the time there's a thin layer of precipitant on it, it's difficult to get more wash fluid to drain off. So, suggestions on washing, or is what we're doing good enough?

Now, once it's washed, what do we do with it? Just evaporate off the fluid over low heat, scrape it out of the container into a container? We did put some of the dried precipitant onto a spoon and heated it to about 700 degrees or so last night, (the spoon was turning red on the tip, but we have a heat gun & it was reading around 700--up to 800 a couple of times). The powder turned a deep red-brown. Pics attached.

Next question, and this is the one we're really hoping to get an answer to:

Is there any way of testing the precipitant at home to see what metals we're pulling, or do we have to spend big bucks and send a variety of samples to a lab? We're working on a limited income for now, and while we'd love to be able to send them in (and eventually will) we're hoping there might be some poor man's tests we can do. Any ideas?

Thanks so much.... here are the pics I promised. The really deep orange precip on a filter was from an experiment we did putting some gold coated industrial pins in thio solution for 30 min., then dropping the same way we have our ore samples. Is it possible we picked up some copper that lay under the surface of the gold, as well, based on the deep orange hue?

The lighter orange color filter was from our ore, after washing, prior to heating.

The closeup of the beaker showing the precip on the bottom was a very small sample, less than 800 ml, and it was still dropping when I took the pic. The pic of the flask shows the golden color we're getting right after adding the ferrous. There were tiny particles dropping but it doesn't show up on camera.

I have never done leaching with thiosulfate, so I am not sure what colors to look for. but that looks like iron to me rust red. what color powder does one gert with gold in thiosulfate?

The powder I get looks identical in color and texture,to the powder I get from AuCl.

mic said:

The powder I get looks identical in color and texture,to the powder I get from AuCl.

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Mic...are you saying you also use Thiosulphate as a leach? I'm not clear what you're saying here, can you clarify, please? Does the powder you get from your ore using thio leach look like this, or entirely different?

If you use zinc as your precipitant,for a thio-based solution,then the powder should look similar to the powder dropped from an AuCl solution.If you are using ferric chloride,or sodium metabisulphite as your precipitant,then I do not know what to tell you.It should be noted that I do not process "ore" from the ground,so there may be a difference ,you will need to ask Rick about that.
Added One simple way to test for PM's in your powder is to boil it in water,to remove any excess thio,and sodium hydroxide,then add Hcl.Wait to see if everything dissolves.If it does,then you know you probably have no values.If it does not,then add chlorine and test with stannous,then compare colors.

I am likely the worlds leading skeptic. A red flag goes up immediately when I read you have an ore the assays more than 5 ounces gold/ton. Not saying it isn't possible, but that's a hugely profitable deposit and not likely to be at anyone's disposal.

That being said, the material you heated reminds me a great deal of iron. Why don't you try dissolving some with HCl, to see what happens? In Hoke you can read of a test for iron, so the resulting solution can be tested.

If, after you've given the material a boil in HCl, there's still some solids present, add a few drops of HCL (at least four), then a drop of nitric. Allow it to work until action ceases (you should have consumed the nitric that way). You can then test the solution to determine if it contains gold. It may not. If it does, and you'd like to determine the presence of any platinum metals, place a drop of solution in a spot plate, to which you will add a crystal of ferrous sulfate. That will precipitate any gold that is present. You can then test the remaining solution with stannous chloride for platinum and palladium. If you get mixed results, you may wish to test another drop with DMG, to determine if there's palladium present.

I'm not optimistic.

How has the ore been assayed? Fire?

Harold

Harold_V said:

I am likely the worlds leading skeptic. A red flag goes up immediately when I read you have an ore the assays more than 5 ounces gold/ton. Not saying it isn't possible, but that's a hugely profitable deposit and not likely to be at anyone's disposal.

That being said, the material you heated reminds me a great deal of iron.

How has the ore been assayed? Fire?

Harold

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Harold, we appreciate your concern and questions, so I'll explain what we've learned so far. We sent two samples of 3 lbs of finely crushed ore to a lab in Idaho that runs extraction tests for large mining concerns around the U.S., as well as doing in-the-field work doing large extractions on tailings, and processes black sands at their facility, all using chemical extraction, and specifically only for gold. They won't take less than four tons of material at a time (and only take on a client via contract for ongoing material). This lab used SSN as their leach, followed with Butyl Diglyme, then oxalic acid. They washed, dried, and measured and gave us the results. One sample tested at 5-7 oz per ton, the other 8-9.

After that, we shipped a 10 lb sample of finely crushed ore to a company that's been in business over 25 yrs, mining, processing and extracting. We spent parts of three days with the man watching him process our ore. He's not a full lab that's able to test for individual pm's after the drop, but he first dropped out the junk metals, then dropped the pm's, and agreed with the Idaho lab that there's a good quantity of microscopic gold, as well as silver. He suggested we send some samples to a lab and have them tested for platinum group, as well as telling us the % of each pm contained.

We have also successfully ran small batches of ore using SSN, butyl, and oxalic. We've talked to the company that manfactures butyl dyglyme, and it will only capture gold, nothing else. We are not excited about continuing to work with nitric as our leaching agent, due to disposal concerns, and wanted to find another one, so we switched to thiosulphate.

Also, I put the wrong picture up of one of the filters....I put the one up twice that had the precip from the gold pins, so I removed it this morning and replaced with the correct 'golden' one that was from an ore run. Sorry about that.

We also know it's not iron, as it's not magnetic, and thio leach, if used properly and not allowed to drop below 9.0 during the leach time, will not pick up iron. We were very careful to check consistently on the ph, and it never dropped below 9.2.

You said: "If, after you've given the material a boil in HCl, there's still some solids present, add a few drops of HCL (at least four), then a drop of nitric. Allow it to work until action ceases (you should have consumed the nitric that way). You can then test the solution to determine if it contains gold."

We basically have done that by taking the precip from the thio leach, putting into solution with SSN, then capturing it with butyl and precipitating it with oxalic. Our question is, is there some other way of running a test on our precip to find out what specific pm's there may be in it?

Harold_V said:

If, after you've given the material a boil in HCl, there's still some solids present, add a few drops of HCL (at least four), then a drop of nitric. Allow it to work until action ceases (you should have consumed the nitric that way). You can then test the solution to determine if it contains gold. It may not. If it does, and you'd like to determine the presence of any platinum metals, place a drop of solution in a spot plate, to which you will add a crystal of ferrous sulfate. That will precipitate any gold that is present. You can then test the remaining solution with stannous chloride for platinum and palladium. If you get mixed results, you may wish to test another drop with DMG, to determine if there's palladium present.

Harold

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Harold, just one more question. What strength of HCL are you using when you bring the material to a boil? We'd like to go through this process so we can test for platinum metals. We have 38% HCL, should we use that full strength, or dilute first? After we've put a crystal of ferrous sulphate in (which is what we're using on the thio leach to drop the metals), and we're ready to test the remaining solution, how much stannous chloride and should the solution still be hot/warm/room temp, or does it matter? And I'm sorry, but I'm not familiar with what the designation is (DMG)?

We don't have any stannous chloride on hand, is that easy to find/purchase?

Thank you again

Dimethylglyoxime = DMG.

A yellow precipitate from an acidic solution is positive for palladium.

qst42know said:

Dimethylglyoxime = DMG.

A yellow precipitate from an acidic solution is positive for palladium.

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qst42...did you take a look at my picture of the golden colored precip on the filter? Do you mean more yellow than that? Not sure....
Thanks!

I have no idea how it would appear in a thiosulfate leach.

But dissolved in AR or nitric, stannous will detect it and with DMG a bright canary yellow.

qst42know said:

I have no idea how it would appear in a thiosulfate leach.

But dissolved in AR or nitric, stannous will detect it and with DMG a bright canary yellow.

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Forgive my ignorance, but I'm not familiar with what DMG is? Can you tell me the procedure for testing with stannous and DMG when using a nitric leach? We often use nitric with saturated salt, and still have left over solution that we'd love to test for any platinum group.

Thanks!

The book by Hoke available as a free download from several members signature line covers these tests and solution preparation better than I can.

qst42know said:

The book by Hoke available as a free download from several members signature line covers these tests and solution preparation better than I can.

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Thank you, we'll check that out.

Ferrell,
The red powder (in your picture above) looks like Iron hydroxide Fe(OH)3 (to me), once this iron compound forms it is hard to dissolve in acids (even aqua regia), this Iron powder, in my experience can also contain gold, which the aqua regia will put into solution easily, leaving the Iron pretty much un-dissolved ,

(But I do not believe this can remove all of gold from iron with this method (aqua regia) as I believe the iron will lock up gold into it, preventing you from leaching it out with this acid solution), (this I do not know for sure), (I believe you would need to convert the Iron hydroxide into elemental Iron to be able to get the Iron to dissolve into solution to effectively separate the gold from it.

(This is a problem I have been working on also).

Iron can also be yellow Fe (OH) 2 insoluble powder.

Not all iron compounds are magnetic (just look at hemitite and magnetite in ore).
Sometimes a non-magnetic Iron compound can be made magnetic by high heating, but also a magnetic Iron can be made nonmagnetic in using heat or chemical process.

Iron in solution can have green color, but can also look yellow or brown, to this rust red rouge color, it can look similar to gold powders,

Iron in solution can be tested using potassium thiocyanate, or ammonium thiocyanate, in spot plate will give a dark blood red color if positive for iron, this is a sensitive test.
(Very similar to stannous chloride test for gold, in that it will test for presence of metal in solution and being so sensitive of a test that will detect traces, and will not tell you how much {although it can indicate clues}).

Do not use this test if much nitric is in solution, because nitric will also give a red color with thiocyanate, mercury, oxalic acid can also interfere with this test, copper can give brown color, which may or may not obscure, the red color of iron.

(Potassium Ferro cyanide will also test for Iron in solution giving a blue color if iron is in solution).

You can read all about this and more in Hoke's book (see page 100 for the iron test).

I do not know for sure the powder in your picture is Iron but I looks like what I cook out of a strongly heated iron solution, it could possibly Iron and gold in those powders together, as I stated I have no experience with the thiosulfate leach, and do not now how it would react with iron compounds in your ore.

Ore almost always has a very high Iron content, many times this iron can have many forms (chemistry involved in ore), and some may leach easily, (magnetic and nonmagnetic), some may cause problems, here is another area that pre-treating the ore can be very important to convert the troublesome compound into none troublesome compounds, roasting these Iron compounds to improve them (sometimes a chemical will be added in the roast, to help change the ore’s chemistry) (like lime, salt, salt peter, and so on). With out pre-treating the ore your leaching process may fail miserably.
Pretreatment of ore in my opinion may have more to do with success than the leach itself does, (many I think overlook this step as unimportant and wonder why they cannot get gold with this leaching processes

With the high gold content in your ore (you stated) I would think you should be able to remove much of this gold by roasting, powdering, classifying, and gravity separating, then leaching concentrates.

Reading Hoke's book will discuss testing values in solution, this is not a mining book but any miner wanting to be sucessful should read it and do her getting aquainted expieriments.

I am just a hobby miner and refiner learning this, so take what I say with a little salt.

butcher said:

I am just a hobby miner and refiner learning this, so take what I say with a little salt.

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Sorry, I don't agree. It is my suggestion that it be taken to the bank, no salt required. Everything you've stated is extremely useful and should be taken seriously. All too many have been mislead by their hopes instead of being properly lead by evidence. Following your advice should (and likely will) provide the needed evidence. It may not be what is desirable, but it will be the truth.

One of the most valuable assets a person can have when working with ores is to remain skeptical. Do not look for minor reasons to support your desire to have what you hope to have---look for reasons why you are achieving results that may be similar to results that you hope to discover. That, in and of itself, will often disclose what is really present, instead of what is hoped to be present.

Iron has tripped up many people that have stars in their eyes.

Harold

Looks like gold to me! I've seen pure gold this color thousands of times. Check out my posts about nano-gold colloids, I think that your gold drop was incomplete. 8) Dr. Poe

Dr. Poe said:

Looks like gold to me! I've seen pure gold this color thousands of times. Check out my posts about nano-gold colloids, I think that your gold drop was incomplete. 8) Dr. Poe

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Thank you! I'd love to check out your posts, could you give me the url to find them, or do I just do a search using those words here on the forum?

You said you think our gold drop was incomplete, can you please explain what you mean?

In reference to the posts by butcher and Harold, (thank you for all your input, we truly do appreciate it) I'd like to emphasize that the dark orange color on the one filter was from a few dozen computer pins. We checked the serial numbers against the manf web site which shows the composition of the pins. There was no iron in them at all, just copper, covered with a thin layer of gold. We assume we probably left them in the leach too long and it pulled some of the copper, along with the gold. I didn't take a picture, but we did half that number of pins a wk earlier, and left them in half as long. The result was a much lighter golden color almost identical to the other filter I posted showing the precip from our ore.

Also, the lab in Idaho told us that they had no problem whatsoever with iron interfering with their tests on leaching and dropping the gold from our ore. Same with the tests run in Arizona. Ore didn't cause any problems. Also, on the threads that deal with Thiosulphate leach, Sawmill stated (and was acknowledged as having the most experience with thio leach) that iron won't be collected or cause a problem with the leaching process as long as the ph is kept above 9.0. Ours was. That's not to say we might not be doing something wrong along the way, and we know we still have much to learn, just stating what was posted by someone else with a lot of experience with thio leach.

Not trying to argue with the experts on this thread, just wanting to point out that we have been researching to some degree already. And that the company in Idaho is reputable and did thorough testing for gold, as did the company in Arizona, so we're fairly comfortable that their results were accurate, if not exact.

I will download Hoke when I'm able. We're on dial-up here at home and it's a 2 MB file, way too big to handle on dial-up.

Looks as though no one has paid any attention to your first question.

"Here's our questions;
Does anyone have a better way of cleaning this product without losing it through a filter?"

If your assays show a minimum of 5ozt/ton, You need to take that to an investor and get enough to get a centrifuge. That should help with the filtering problem.

tlcarrig said:

"Here's our questions;
Does anyone have a better way of cleaning this product without losing it through a filter?"

If your assays show a minimum of 5ozt/ton, You need to take that to an investor and get enough to get a centrifuge. That should help with the filtering problem.

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Thanks for your excellent suggestion, Terry! We've talked briefly about this possibility in the past, but are a bit leery of doing it. The ore deposit is on our own home property. We want to do it to make an income, pay off our home, etc., if it all works out. If we involve an investor, our concern is they'll want to go deeper/faster/and take more out that we're comfortable with, potentially destroying the aesthetic value of the land. It would be great if we could find the right kind of person, but as investors typically want a sizable and somewhat fast (if possible) return on their money, it could lead to problems we'd rather not deal with, if that makes sense.