Iron(II)-chloride for precipitation

[Alkymida]

Hi all

I´ve used Iron(II)chloride for precipitation of gold many years ago with good result and wonder why i can´t find anything about that?
To me it was very easy to make and work with and it precipitated instantly after evaporation and dilution of goldchloride with water.

Best regards
Peter

 

[ericrm]

that is very interesting ,please tell us more

 

[Alkymida]

Hi Eric

When all metal is dissolved in AR (3:HCl, 1:HNO3) and you have evaporated excess acids by heating whithout boiling you end up with a syrup-like substance which is taken off the heat to cool.
You now have ruby-red crystal-mass of AuCl3/AuHCl4.
Then you dilute in water to a citrus-yellow liquid.
While evaporating you can prepare a fresh portion of Iron(II)-Chloride by dropping some iron in konc. HCl. I used some small nails in excess and got a saturated blue liquid.
I then added this to the goldsolution drop by drop with a pipette. When a drop hit the liquid it instantly made a dark/black "cloud" in the liquid which quickly sank to the bottom of the beaker. I kept adding drops till no more dark turned up.
Then i filtered, rinsed and dried the gold.
After that i sintered the powder to form metal. :0)
I think it was very easy to work with and funny to see the gold form in that way.

The procedure i read in a chemistrybook from 1972 (i got for Christmas that year):
Paul Bergsøe: "Kemi på en anden måde" (Til selvstudie af uorganisk kemi) ~ "Chemistry in Another Way" (A tutorial in inorganic chemistry)

EDIT: Spellings and i might add it was 32% HCl and 67% HNO3.

Peter

 

[maynman1751]

I have made and used ferrous sulphate to precipitate but never the chloride. How long does it take to prepare this solution? Interesting, Thanks!

 

[Alkymida]

Hi maynman

The iron nails dissolves quickly - a little slower than zink.
You don´t need much.

If you take the nails out the Iron(II)chloride will turn into Iron(III)chloride. Yellow stuff for dissolving copper on PCB-boards.

EDIT: PBC-boards to PCB-boards

Peter

 

[hfywc]

very interesting but wouldn't this contaminate the gold you are trying to refine?i would say this is useful for initial recovery or in cases where there are no other precipitant available.

 

[Geo]

ferric chloride would indeed contaminate the gold. its best to keep other metals out of your solution if you can.

if it was feasible or a viable alternative, one of our more learned members would have suggested such a simple and common precipitant a long time ago.

 

[Alkymida]

Hi again

I thought about that too. But on the other hand you only use what is needed to precipitate.
It was because that was the one i learned to use years ago i asked why it wasn´t mentioned.

Best regards
Peter

 

[ericrm]

what happen to the ferrous chloride after it has drop the gold ? what does it become?

 

[Geo]

Peter, that is what this forum is all about. learning a better way. there are many compounds that will precipitate gold from solution, but just because they drop gold from solution doesnt mean its better than the next. as a matter of fact, there are many that are far worse to use than others because they will contaminate your refined PM's. here on the forum, we try to weed out misinformation. any new member reading this thread may be thinking "if this guy says this will work and its cheaper and easier to get than what everyone else says to use, im going to try it". the next thing you know, we will have a rash of questions of people wanting to know "why is there iron in my gold?" and "i followed directions from the forum and i still cant get my gold pure".

im not busting your chops about this and i understand your just wondering why you were taught to use it a long time ago and no one here seems to know anything about it. i promise you, if it drops gold, a large percentage of members here know about it but would rather do it the right way.

 

[Barren Realms 007]

It will also drop your copper and other contaminants during the precipitation and leave you with a dirtier gold to deal with.

 

[Alkymida]

Hi again

Eric: It will turn fron Iron(II)chloride to Iron(III)chloride.

Geo: I see what you mean. Maybe it was because the textbook only was dealing with how to dissolve and recover gold, not when other impurities are mixed in.

Barren Realms 007: Yes and no. If i just put a lot in it will as you say precipitate the other metals. If i use it dropwise i will stop as soon as the precipitate doesn´t fall very quickly to the bottom. It´s in a very diluted liquid it´s done.

Best regards
Peter

 

[hfywc]

peter,

thanks for sharing your little secret!

regards,
alan

 

[Geo]

Peter, if you dont mind me asking. how long did it take you to get to where you knew when to quit adding the iron chloride? i guess what im saying is, did it work as expected the first time you did it without any issues. and second, did you have any problems with contamination of the final product or did you check for quality?

 

[qst42know]

Ferrous sulfate is known to be selective and easy to make. I'm not enough of a chemist to stray from the known paths. :mrgreen:

 

[bmgold2]

I've been looking for this information for a while. What I have been doing is trying to get The Gold Hunter's Test Kit that I purchased recently to leach gold from some bought gold ore that I got from Action Mining that is supposed to have at least one ounce of gold per ton in it. I have been trying lots of things to get it to show a positive test for gold and have had no luck at all. I do get and orange test from the stannous chloride (or whatever their test chemical is) and am pretty sure that is indicating iron.

If there is iron in the ore, will that keep the gold from going into the solution or precipitate it back out if it does leach?

bmgold2 - former bmgold but couldn't get my old password changed and can't remember it

 

[butcher]

I would not waste my money on the The Gold Hunter's Test Kit, My daughters bought me one for my birthday years ago, it did not work, I suspect the chemicals they use have a shelf life, and if you do not get a fresh kit it will be useless, I could not determine what the kit was for sure, its been so long ago, but I suspected it some type of thiosulfate or iodine leach, the chemicals of the leach I believe because of the dangers involved they chose fairly safe chemicals for their product, as shipping of more dangerous chemicals would become prohibitive, whatever the kit contains it is surely nothing that you could not make on your own with a few chemicals and a little know how.

Iron will leach form ore before gold will with most of the chemical leaches we use, iron in solution can look very much like copper (green) or gold (yellow) when dissolved into a solution.
other base metals will also leach from an ore of group of metals before the more noble metals will, so unless the leach is selective for a certain metal, we can expect the more reactive metals to dissolve out of solution first.

Try this test on your ore:
Powder the ore, a pinch of the ore, in a surplus mix of one part ammonium chloride, and 21/2 parts ammonium nitrate powders, mix well fuse these together with heat to a molten syrupy molten salt, cool some and add a few drops of HCl to dissolve the salts in solution, dip a Q-tip into this solution and test with fresh stannous chloride. this test can be done in the field with some simple tools in a kit, basically the NH4Cl and NH4NO3 salts in a molten fused state with the gold in the ore act similar to aqua regia, the fused gold chloride salt dissolved in aqua regia, can be tested with stannous chloride, a very sensitive test for gold ions.

With some ore it is better to flux out the base metals, and use a collector metal in the flux, then a cupel, and or use acids to see what you may have.

One ounce a ton? that sounds like a fairy tale. How much did they charge you for it, I know that store does not give anything away cheap, but nobody sells gold cheap or gives it away. Have you tried crushing roasting and panning the ore? with that much gold I would expect to see gold in the pan.

 

[bmgold2]

The Gold Hunter's Test Kit is a saturated salt and nitric acid leach according to their website. The indicator solution is NOT stannous chloride according to what I have read somewhere online. It is supposed to last longer than stannous chloride.

I am now thinking that something in their indicator solution is reacting with the iron and causing an orange color to the spot test. I added some known good gold containing solution to a small sample test of black sand which was giving me the orange color test. With the kit's indicator, I got the orange spot with a purple spider web around the outside of the spot (on paper towel). Then I tried a homemade stannous chloride test and ONLY got the purple spot.

At least that tells me that the iron containing solution didn't precipitate the gold. It might keep it from being dissolved in the first place (I didn't test it again yet).

As far as the Action Mining ore, it says it is guaranteed to contain at least one ounce of gold per ton. If I'm calculating right, $1200 oz divided by 2000 pounds equals 60 cents per pound. It cost me $7 plus shipping (over $10) for that pound of ore. It was sold as test ore for their assaying kits so I expect it really does contain that much gold.

I did try panning some and found no indication of free gold. I roasted some and panned it and still no visible gold. I'm pretty sure the kit would work if there was free gold in the sample (if your pinch of ore contained the free gold). Actually, if it contained free milling gold, crushing and careful panning would tell me if there was gold in it and the kit wouldn't really be needed. It is more a yes/no test and not really an assay to tell how much gold is in the ore. The color should give you an indication of how much gold by the darkness of the purple spot but not really a substitute for an assay. Might save you from sending in poor samples though.

I do plan to make my own leach and indicator but wanted to try an already made kit before trying it on my own. Not sure if that was a good idea but that's what I did. Now if I can just get it to find some gold, I'll be happy. It does dissolve gold. I used it along with a link from a gold chain to get my solution to test the indicator and my own stannous chloride tests.

I'm going to try leaching the bought ore again when I'm done playing with the last test. It is in a 1 dram glass sample bottle and it is the only one I have left. I broke the other one that came in the kit.

bmgold2

 

[butcher]

I do not know if the Gold Hunter's Test Kit has changed chemicals or not, mine could have been The SSN/HNO3 or brine and nitric leach, its been so long ago and my memory is bad, and that seems very likely it did, I know they would have shopping problems with many of the chemical needed, and their kits would be made around that.I do not know if it was the leach or the test solution that went bad with the shelf life of the kit I had, but I do remember It did not work.

Basically the brine and nitric leach (SSN) is an aqua regia (substitute) it is very similar to aqua regia, it would not be good long after mixing, just like aqua regia, it is gases formed that are in large part responsible for oxidation of the gold, these gases do not stay in solution long, can be driven out faster with heat, and would not have a long shelf life.

The two best known reagent to test gold in solution would be stannous chloride, and ferrous sulfate, the stannous chloride gives the violet color of colloidal gold purple of Cassius, the stannous chloride has s fairly short shelf life, especially depending on how it is made and stored, if stored in absence of air or oxygen, and with a piece of free in with a little free HCl it will have a bit longer shelf life, in the clear solution that came with the kit, I do not remember seeing any metal in solution, and the fact the solution was clear lead me to believe it was stannous chloride in the Gold Hunters test kit, ferrous sulfate or copperas would be a green solution (if not oxidized to some other salt of iron), and the test would give a brown reaction of precipitated gold, another reason I believe the kit contained SnCl2, and not FeSO4 in the kit.

I just knew I could make my own kits to do the tests.
I just soon viewed this kit like Shor's, taking common chemical and known tests and relabeling the chemical, to gain a dollar in the market.

If you cannot crush and pan visible gold, and if the ore is as high a gold content as advertized, this leads me to believe the gold is chemically bound microscopic gold in the ore, (I also assume you roasted the powdered ore before panning).

I would also roast the ore before leaching, if you do not your acid leach may not be able to pick up the gold bound up chemically like in a sulfide ore.

It does sound like Action mining is making good money on that rock, so I guess it could contain gold? Call me skeptical I do not believe rock has gold until I see it myself. :lol:

You could also test your Gold Hunters test kit, using their leach on a known gold, and trying the test with their test solution and your own homemade SnCl2 solution. Or making up your own leach solution and test the test their test solution against your homemade.
Also testing their leach and your leach on the ore, You could even try to recover some gold from the ore with a smelt to see how that worked as opposed to leaching, also not all leaches will be effective with all ores, sometimes the ore itself can counteract the leaches ability to dissolve gold, the ores have a chemistry of their own that can affect the chemistry of the leaching solution and the gold.
Basically using different tests to find out what is working and what is not, and experimenting to try and find something that will work.

 

[bmgold2]

Thanks butcher,

Their indicator is clear. Somewhere I read that it contains "something" to keep it from going bad. As for the leach itself, their site states that if it goes flat you can add a little nitric acid to it to restore it. Salt water is pretty cheap and available so ...IF... you had nitric acid to add, you could just make it yourself.

I did use their leach to dissolve some actual gold and it worked fine. Both their indicator as well as my homemade stannous chloride showed the purple or black color depending on how much gold was dissolved. What changed was when there was iron or another metal in the solution with the gold. Then their indicator gave an orange or almost brown color where my homemade stuff didn't do that. My only guess is that whatever else is in their solution is reacting with the iron.

I did roast the ground up ore but might not have done it right. What I did was to add the ore and some table salt to a stainless steel dog dish and put in in a wood furnace. I only left it in for a half hour or maybe 45 minutes. I kept checking it/stirring it and when it was hot (dish was glowing - not sure if the ore was glowing) and then cooled it down. I didn't think to dump the ore immediately into cold water so that could be part of the problem. After that, I panned (actually just fanned it around the pan since there wasn't that much in this test) and couldn't find any free gold showing up.

I have another pinch of the ore that I "roasted" in the vial along with some more leach solution and will check it out in a while to see if it caught any gold. I'll likely leave it at least overnight since it is not real warm. I'll let you know how it turns out. I need to find my propane torch and some propane to try heating up the ore quicker and easier. My oxygen tank is real low and my acetylene tank is empty or I'd have used that.

bmgold2