Suggestions for getting sulfide-bound gold from iron ore?

Mlandri · Dec 26, 2014

I'm new to hard rock gold mining, so apologies if I'm asking a nube question.

Can I smelt out gold from ore if the gold is bound with sulfur and the ore has a cap load of iron?

First run in my first diy cupola furnace gave me a lot of pig iron and cool slag, but the gold content isn't obvious.

ConceptualizedNetherlandr · Dec 26, 2014

Are you sure there is gold there? If so at what concentration? Imagine how many tons you might need to smelt to recover an ounce.

Mlandri · Dec 26, 2014

As sure as I can be using basic field tests. Challenge is that it's only visible under magnification and only AFTER rock samples are roasted. Ironically, I wasn't expecting gold in this ore, since I didn't see it when I crushed and examined early samples. I had planned on smelting out iron and perhaps the smaller amounts of copper that I already knew about. I noticed the gold after I burned my ore to make it easier to crush.

My first assumption that the material was mica or pyrite. However, the ostensible gold is malleable and passes the streak test. Good signs but not a slam dunk. If gold, then the concentration is certainly high enough to warrant further investigation.

I could send the ore off to be assayed, but where is is the fun in that? Also, I'd want to know more about the gold content before sending it off to someone that I don't know. Hence my question!

azblackbird · Dec 27, 2014

Mlandri said:
I could send the ore off to be assayed, but where is is the fun in that? Also, I'd want to know more about the gold content before sending it off to someone that I don't know. Hence my question!

That's kinda the idea behind an assay. If the ore assays high enough, all you would need to do is worry about how to get it out of the ground and to a refiner.

Mlandri · Dec 27, 2014

Sure, eventually. Personally, I'd first want to have a rough understanding of the (ostensible) gold distribution differentiated by ore characteristics and location. This info would permit me to more smartly chose ore samples to send off to a professional and subsequently better interpret and make decisions based on the results. Additionally, a rough estimation allows me recognize if the results I receive back are likely reasonable or if perhaps I should send samples to a different assayer to double check.

More knowledge is more better!

Mlandri · Dec 27, 2014

I've found some resources describing cupellation. Also, had someone recommend that I read up on an old but useful approach that uses a blowpipe to carryout quick field assays. Seems like one or both of these approaches might meet the need.

prospect007 · Dec 31, 2014

roast, crush, table, smelt into bars.

Eu_citzen · Jan 5, 2015

Some thoughts about assays:

Send random pieces to assay, "choosing" pieces may lead to wrong assumptions. Just an idea.

Sending multiple pieces for assay may give an indication if something is wrong, although it isn't a bad idea to occasionally double check some assays, most of the times there'll be no problem.

Every piece should be about fist-sized or near 1 Kg for assay.

As for the testing at home, what minerals are you dealing with?
First thought is what prospect007 said.

jair · Jan 5, 2015

I do simple assay's .
If you are looking for as accurate as possible of an assay . You can not send selective ore .
That is most all the problems with assay's .

Mlandri · Jan 6, 2015

Appreciate all the comments. Sounds like I'm over-thinking this problem. Next question. How do I find a reputable assay company?

By way of an update, Chapman's flux has helped me better id how much gold is in this ore, a lot more than I anticipated. Unfortunatley, I still can't cleanly separate it from all the iron. I didn't realize how humbling this process can be!

Chapman's flux helps pull our the gold but still leaves it swirled in glass. In part, I need to make the melt less viscous. I'm sure there is more to the problem, however.

Regards,
Mark

snakejim · Jan 6, 2015

You are wasting your time trying to melt the gold out of the iron.
Roast the ore, crush it, pan it out (or run it on a table as prospect007 said). You have to get rid of the iron. Maybe try a magnetic separator. Then melt your gold.

Plbnyn · Jan 7, 2015

prospect007 said:
roast, crush, table, smelt into bars.

Prospector007 What do you mean by roast the ore is there a Temp to get to, a size of ore to roast and is there a time of roast. Any direction for research would be greatly appreciated

pczim · Jan 7, 2015

Simple, remove any unwanted minerals with acid. Would also recommend using merc however that could be controversial depending on your location and beliefs.

ConceptualizedNetherlandr · Jan 8, 2015

pczim said:
Simple, remove any unwanted minerals with acid. Would also recommend using merc however that could be controversial depending on your location and beliefs.

Please explain 'beliefs' as used. Thank you !

pczim · Jan 8, 2015

ConceptualizedNetherlandr said:
Please explain 'beliefs' as used. Thank you !

Some folks believe that mercury causes significant damage to health and environment and as such it is banned in some countries.

bobw53 · Jan 8, 2015

ConceptualizedNetherlandr said:
Please explain 'beliefs' as used. Thank you !

I believe that I'm not smart enough or responsible enough or knowledgeable enough to be playing around with mercury.

prospect007 · Jan 8, 2015

crush the rocks to thumb size and smaller, put in cast iron frying pan , build a good hot fire, place pan on fire for a couple of hours to drive off the sulfides, then crush to powder, table the powder, melt gold into bars. sounds easy, it's not. it's time and labor intensive.

Plbnyn · Jan 8, 2015

prospect007 said:
crush the rocks to thumb size and smaller, put in cast iron frying pan , build a good hot fire, place pan on fire for a couple of hours to drive off the sulfides, then crush to powder, table the powder, melt gold into bars. sounds easy, it's not. it's time and labor intensive.

Prospect007 thank you for the response been reading technical papers or a grand scale written by educated folks Plbnyn

dredgeman · Jan 9, 2015

We are using bio remediation to get rid of the iron and sulpher.
Treat with bugs and fire to metal.

Plbnyn · Jan 9, 2015

dredgeman said:
We are using bio remediation to get rid of the iron and sulpher.
Treat with bugs and fire to metal.

Where do I find more on bio remediation? And then a new guy question how do you know when there is a sulfide on the gold. I have read about the chemical makeup of sulfide. I know that I need to crush to thumb size roast in a pan and then crush and pan or table I understand cupellation and pressure vessels and heat I still don't know how to identify a sulfide.