Iron(II)-chloride for precipitation

[butcher]

For some types of ore roasting with salt can be beneficial, (depending on the ore type and the leach you planned to use), it can help to convert the gold to chloride in the high heat, a down side to this is that it can also fume off some of your gold as gold chlorides are volatile at these red hot temperatures.

Roasting sulfides in air can help to break down the sulfide bond, driving off sulfur oxide gases, sometimes these bonds are hard to break, and an iron powder can help to break the bond, gold giving up its bond with sulfide to the iron, then iron releasing them easier with the heat as sulfur dioxide gases, But of course we are adding more ore to be leached latter.

Grinding fine and roasting red hot in air or oxygen is important to break the chemical bonds, the exposure to oxygen or air is just as important as the heat needed to oxidize the ore.

Sometimes it is best to heat the ore for a while before bringing it up to red hot in the roasting procedure, to help drive of volatile gases, before oxidization in the red heat.

Oxidation can help also with iron in solution, as iron oxides (hydroxides) are not as soluble in many leaches, this can help some to lower the amount of iron your leach pulls into solution before or with your gold. it can help other to oxidize the base metals in the ore, be leached into solutions if you are pre-leaching the ore for base metals before going after the gold.

Like double edged swords, it may work but it may be easier to cut yourself.

Ore as you know is complicated and it can complicate getting gold out, not every leach will work with every ore, and in mining many times they have to do a lot of experimenting to find a way that will work to get the gold.

Be careful with the fumes of roasting and acidifying the ore, some of these can produce extremely deadly gases, arsenic is one you would not want a lung full of.

The SSN leach would be a weak leach in my opinion, even if mixed up fresh, basically how it works is a portion of the nitric acid converts some of the salt in solution to HCl acid, this along with nitric acid forms an aqua regia, in a high brine solution, aqua regia forms gases that oxidize the gold (along with the nitric acid) the oxidized gold is picked up by chlorides in solution, when aqua regia is freshly made these gases are in solution to do work, if the aqua regia was prepared a long time before we used it it would not be as effective as we would not have these volatile gases in solution to attack the gold, this is why you always prepare your aqua regia fresh, and not make it and store it for use later. I suspect the SSN would be the same, sitting on the shelf it would not be as effective, but the salt solution could be regenerated with fresh HNO3.

The SSN leach may or may not work with your ore, or you may be leaching base metals and the leach is so loaded with base metal and there is no room for gold, or you can be getting gold into solution with your base metals from the ore...

Well sounds like you are having fun and are on the right track keep us posted, I would like to know what you get out of this ore.

 

[FrugalRefiner]

As butcher has pointed out, roasting ores is a complicated issue. Different ores have to be treated in different ways. What works with one ore may increase your problems with a different type. There is some good information in T.K. Rose's book, The Mettalurgy of Gold. It's a very old book, so it is out of copyright. It is available as a free download from Google books as well as other sources.

Dave

 

[bmgold2]

Well, I finally got a positive test for gold from the bought ore. It's not a very dark stain but it is a light purple. I ended up using my own stannous chloride instead of the kit's indicator. The kit's indicator is still showing an orange color.

Reading through Hoke's book, it looks like stannous chloride does NOT give any color from iron, copper, zinc, nickel, or cadmium so I don't know what the kit's indicator is but that seems to have been my problem. I wonder how many of my original tests actually had a little gold in them?

I'm going to let the ore leach for another day in case it dissolves a little more gold but at least now I know there is gold in the bought ore. This ore (at least an ounce per ton) might not be the best ore for a small scale miner to deal with but I'd hate to pass it up if I had actually found it instead of bought it. I'm sure a big company would be interested in it considering they deal with much lower grade ore. I'm going to continue experimenting with it and hopefully get a little stronger indication of gold from it but considering the small amount of ore I'm dealing with in my tests, I'm happy that I got any indication of gold out of it at all.

Next step will probably be trying out some homemade leaches. My main reason for buying the kit instead of making my own in the first place was the difficulty and expense of getting nitric acid. I'm just playing around and trying to learn a little bit along the way so I can't really justify buying nitric acid since I don't have my own ore (that I know of).

bmgold2

P.S. another book I found online that has some information about roasting ore is:
Leaching Gold and Silver Ores: The Plattner and Kiss Processes. A Practical Treatise
which can be downloaded HERE:
http://www.google.com/url?sa=t&rct=...HerGSTiV8WHhfnR0XlWto8w&bvm=bv.58187178,d.cWc

 

[butcher]

Thanks for the link to the book.
If you have too much trouble getting nitric acid you could just make your own.

I just read a little of the book you linked, what is obvious to me is they were using salt in their roasting process mainly because of the way they were going to be leaching the gold, also later in the book He speaks of where they were losing much of the gold in the ore, He traced it to the roasting process they were using, vaporizing off considerable amounts of their gold (roasting the ore with salt).
I would like to spend some time reading that book.


The stannous chloride test is extremely sensitive, it will detect very minute amounts of gold in solution.
The hard part may be to get those gold ions into solution.

 

[bmgold2]

Thanks again butcher,

I have everything I need to make "poorman's nitric" so I'll have to give that a try. I still have the leach from the kit that should last me for a while (unless it goes flat) since my tests are only using maybe 5-10 ml. each. Of course, I might try a larger leach once I figure out the pre-treatments needed to get the gold out of the bought ore or find some rocks that show signs of gold.

The only part of the book I read so far was the roasting part. Looks like I'll need to print out another huge book. I just printed out Hoke's book and have only just leafed through it so far although I did read some of it before.

bmgold2

 

[butcher]

One way to prove if the leach in your kit was a saturated salt solution, you could take a small sample of the leach, add a little silver nitrate solution, if you get a white milky solution of silver chloride, it would prove it a saturated salt (or chloride type leach).

If the leach is SSN, I do not see why you could not just add a bit of nitrate salt and a little H2SO4 to it.

Better yet just make up your own SSN Leach, with saturated NaCl and some of the poor mans HNO3 (after chilling) to remove most of the sulfate salts.

After reading Hoke's book, try the experiments in the book, these will teach you how many metals react in acids, these and the testing experiments, will be very valuable tools for you in this field of work.

 

[bmgold2]

Just a quick update on my experiments. I tried another test of some rocks I had. It was a piece of granite (I think) that a friend gave me that came from his hunting trip to Colorado or Wyoming (I don't remember which he said).

This rock was around a pound and a half and I am getting a light purple spot from my own stannous chloride and an orange spot from the kit's indicator. I guess I should have tried making my own indicator solution before buying the gold ore. Now I wonder if my black sands did contain gold. I already leached them once and thought they didn't contain gold due to the orange test results so I doubt I'll try again. I didn't throw any leach samples out but they are all mixed.

At least now I have enough proven ore to try making my own leach solution when the stuff I bought runs out (for testing purposes - not enough to bother recovery yet).

Thanks for the help here.

bmgold2

 

[bmgold2]

Here's my results of testing to give a better idea of what I was talking about.

My positive test is not showing a lot of gold but looks like (to me) that it is a positive test. The KD-3 turned orange and did not indicate gold at all. Perhaps my leach doesn't contain enough gold to be worth showing up but I did want to know if there was ANY gold at all. My leach temperature was probably not high enough or my tiny sample just doesn't contain enough gold to show up with the kit. More experiments should get me closer to figuring this out but I'm getting closer.

 

[butcher]

Stannous chloride is extremely sensitive for gold in solution, it does look like it reacted, but from the looks I would say you do not have much gold in solution, just enough to say there is something.

Leaching ore can be difficult, sometimes other metals in the ore would rather dissolve before the leach can attack gold, the chemistry of the ore can affect the leach, sometimes the gold can be in such a state the the acid cannot hardly reach it, or may not break the compound the gold can be locked up in. This is one reason with testing ore fire assay's normally work much better to determine if the ore contains gold.

 

[bmgold2]

I'll let this thread die soon but just wanted to post about one more experiment.

Last night I leached some black sands that still contained a lot of magnetic black sand. The tests started out the light pink and then got to a dark purple. This morning, the test showed NO GOLD at all.

I'm just guessing but I'm thinking the iron from the black sands got dissolved to the point where it dropped the gold back out of solution which would confirm my thoughts that the iron was keeping the gold from getting into the leach.

I'm happy that I got any indication of gold from my rocks and sand but, as seems to be the general opinion here, trying to get gold out of rocks on a small scale is just not going to pay out. It's still fun to check them out though and that was really the purpose of the test kit I bought. Recovering gold from electronic scrap might not be a whole lot better since you need a good quantity of scrap parts to get a recoverable amount of gold also. Of course, if you save the steel, aluminum, copper, etc. maybe you can make a little bit from the process.

I'm not quite ready to give up yet but I'm considering it more a hobby than a money making process. I'm not in an area where I can go pan material out of the river with any expectation of finding gold so smashing up rocks seemed like a good idea. I spent days working in the hot Arizona desert when I first got into gold prospecting over a decade ago for a few pieces of gold that required good light and maybe a magnifying glass to see and had fun doing it so I guess this hobby is more than just getting gold. It's the adventure of FINDING it.

Thanks again,
bmgold2

 

[butcher]

The best way to get that gold is with an education, knowing what to look for and where to find it, knowing if it is worth going after or not, knowing the value of scrap, and knowing how to recover and refine.
Basically it is the knowledge, education, and understanding that gets you gold, along with that hard work.
Gold will always be hard work to get, but without knowledge you are wasting your time trying to get it.

This is a good reason why study can be so valuable, without knowledge we can be working for nothing, or lose what gold we have, with knowledge we can determine if it is worth working for and know how to do the work.

It is about education which can be more valuable than gold, it is the knowledge that helps us to get that gold.

 

[NeMonstr]

Make a strong solution of tin chloride. Soak paper in the solution. Drying paper. Close the paper in a jar. Store in a dry place. To use the tear off a piece. Drip solution with gold on paper.
Stored for a long time.