Gold Extraction - possible small mining claim in Qld

[Phoenix76]

G'day all, Just thought I'd try and pick some brains out there. Must be a lot of experience amongst the forum members so maybe you can give me some thoughts.

Mate and I are sussing out a possible small mining claim here in Qld. It will be alluvial mining with perhaps shafts to 40ft. Attached picture is a sample I picked off the top of a mullock heap, a little blurry but you get the idea. Only a small piece but I cracked it open after seeing a little colour on the outside. I am going to dolly up the pieces and pan off the results to get an idea of what we could be looking at.

Given the history of the area, this sample will probably have some silver in it. My question is - what methods would you blokes advise for extracting the gold from the final wash? Obviously we have the usual practice today of cyanide leaching, and there are other chemical methods of achieving our aim. I don't have a personal problem with using chemicals because I already do so in recovery of gold from e-waste. They are not very nice substances but handled properly, they give excellent results and are really quite safe to use if you follow all the correct procedures including safety.

This is all a little way down the track as yet, but forward planning is an essential part any future business enterprise.

 

[AtomRat]

It looks like a high content of sulfides or chalcopyrite. Host rock looks interesting like a serpentine or granite?
You can use the same chemical process to extract the au but you need to be careful of the reactions and fumes emitted from the rocks you are getting the color from. For example.. you've gotta watch out for arsenopyrite as it will fume arsenic.. other have a high amount of chlorine and other nasties. You need to look up your rocks and what's going to happen in the process or if you need to alter anything.

Your still on a mission to make chloroauric solutions. If your dealing just with sulfides, they need to be roasted..again emitting nasties. Extracting the au and then testing the solutions with stannous chloride to test if there's gold in the solution etc just like refining ewaste process.

I havnt tryed the smelting and 'dore' method yet in a crucible with borax

 

[mbasko]

I see CSIRO have developed a way of replacing cyanide with thiosulphate which is a non toxic chemical. One of the big companies is set to start using it or may have already?
http://www.csiro.au/en/Research/MRF...Australian-ores/Gold-recovery-without-cyanide
They may even be open to assisting a small scale operation set up & trial?

Theres also some interesting methods here even though it is to do with removing the use of mercury in small scale/artisan mining. On page 56 on there is a method of crushing, milling & shaker table that gets about 70% of the gold from hard rock. You keep the tailing for later chemical leaching to get the remainder but this could be a method of getting some extraction yourself then possibly having a minimally ran cyanide leaching set up or remove your risk altogether to a processing outfit?
https://docs.google.com/a/artisanal...sZ29sZC5vcmd8YWdjMXxneDoxZjQ0YWYzMjIyMWQ3NjA1

 

[Phoenix76]

AtomRat - In this case the host rock is granite or decaying granite. In the area in question there is little quartz which we would normally associate with gold. It is quite variable but decaying granite and ironstone are regular hosts as well as occasional quartz. And yes, if I can end up with a solution of auricchloride I would be quite at home. Very similar to the aqua regia process with e-waste. Guess my concern is with the reaction of AR with the host rocks against say gold plated steel pins or the like. And mate, no matter what chemical process you use, you will have to deal with certain nasties. But I'm well equipped with the appropriate respirators and etc. The borax method you mention is interesting. This method has been taken up by some island populations and seems to have some support. Perhaps I need to read more on the subject. I know it's not the thing one should be saying, but the nasties you mention, arsenic, chlorine, sulphides etc, can be removed through boiling processes. Don't mention that to the EPA .

mbasko - I have downloaded both the links you have supplied for later reading. At first glance they appear to be interesting. I'm able to get most chemicals needed for most processes. Needless to say, I prefer to use the less toxic (dangerous) methods, but sometimes this is not possible. Mercury is not a chemical that I would want to get involved with, although I have handled it, but Nitric, HCl, Sulphuric and the likes are no strangers to me. As I have said, if you handle these chemicals in a proper manner, they are not as dangerous as often believed.

Crushing your ores as finely as possible is the best approach. But at the end of that you need to be able to extract the gold in as pure a form as possible. As mentioned, in our case, silver is normally included in your gold, and the separation is no great problem. The problem may occur when you also have the likes of arsenic and various sulphides to deal with as well.

Thanks to you both for your input. I'll go and do some reading.