Possible impurities in AP dissolution

[Tauran]

Hi guys

I've been away for quite a while and I've just re-interested myself in refining. now here's the story.

A buddy of mine brought me some sand with suspected gold flakes and asked me to figure out if he was right. long story short I am pretty sure its gold (I didn't test with stannous as I don't have any solder, so I figured it out the long way)

after some pretty careful panning of flakes between 75 and 600um I ended up with around 46g of assorted sand powder (from 5kg of gravel).

now here's the annoying part... I was going to leach the whole thing and do a rough assay to determine potential yield and I mixed up the Chlorox method with the AP method. so I added peroxide (to a conc of 1.5% V/V) instead of bleach to my 32%HCL. (stupid mistake but there we go)

the result I didn't expect was the AP went a very dark red and fizzed for an hour or so.

now I live in Australia and the sand came from an inland creak bed. there has been no volcanic activity here for at least 300,000 years so I am almost certain there is no "black sand". however we do have a high concentration of iron oxide. (hence why Australia is red in the middle)

I am wondering if the colour change was iron oxide or some reaction between the Bunnings brand acid and the pharmacy brand peroxide.

If anyone has any experience with refining from prospecting in OZ I would really appreciate some input. even a link to a post I missed would be great. also if there is a better way to do this kind of assay?

thanks in advance

its good to be back

 

[butcher]

I normally do not use acids to judge if it is gold or pyrites (iron ore),
after panning for years I have no trouble telling the difference.
Gold is heavy much heavier than iron ore, iron will pan off fairly quickly with the gravel and sand, if in small flakes pyrite will most of the time pan off easier than the very light sand.
pyrite or iron ore will break to pieces when crushed, gold will flatten or smash flat under a hammer.

Here is a test you can use , to improve you panning skills and it will also help you determine if you have gold in your pan, I will use this as an example of learning how to pan gold.

Take a large tub filled full water to pan into using the water in the tub to pan with, anything you pan off is dumped into the tub and can be re-panned later if you mess up.
Now take your 5 gallon bucket of rocks gravel and sand from the river bed (if it has gold involved all the better). cut you up several pieces of lead say 6 pieces of the size you would expect gold (a very small nugget, and down to fine gold flake size) put these 6 pieces of lead in your pan mixed with a pan full of rocks sand and gravel (you can put the lead on top to begin if you wish.
Now pan this off (washing dirt or mud off of rock in the pan,removing large rocks by hand and panning out gravel and sand, as you remove material from your pan your left with the heavier material (normally sand and your lead and any gold, keep panning you will pan off the lighter sand leaving black sand and your lead and gold, now carefully pan this black sand off, you will be left with your six pieces of lead and any gold if involved (any pyrite or iron ore has been panned off long ago, if you cannot pan everything off leaving just those six pieces of lead (and any gold), you need more practice panning, to practice re-pan that tub full of rock gravel and sand to recover your lead and get the gold you dumped out of your pan.

From your description at this point it sounds like you have fools gold.

There are several chemical tests you can use to test both iron solutions or gold solutions you will find them here on the forum (I have made several posts on this topic as well have many other members, but you cannot improvise these test as it sounds like you have been trying to do.

You can also find how to test for gold or iron in solution by reading Hokes book.

 

[Tauran]

I normally do not use acids to judge if it is gold or pyrites (iron ore),
after panning for years I have no trouble telling the difference.
Gold is heavy much heavier than iron ore, iron will pan off fairly quickly with the gravel and sand, if in small flakes pyrite will most of the time pan off easier than the very light sand.
pyrite or iron ore will break to pieces when crushed, gold will flatten or smash flat under a hammer.

Here is a test you can use , to improve you panning skills and it will also help you determine if you have gold in your pan, I will use this as an example of learning how to pan gold.

Take a large tub filled full water to pan into using the water in the tub to pan with, anything you pan off is dumped into the tub and can be re-panned later if you mess up.
Now take your 5 gallon bucket of rocks gravel and sand from the river bed (if it has gold involved all the better). cut you up several pieces of lead say 6 pieces of the size you would expect gold (a very small nugget, and down to fine gold flake size) put these 6 pieces of lead in your pan mixed with a pan full of rocks sand and gravel (you can put the lead on top to begin if you wish.
Now pan this off (washing dirt or mud off of rock in the pan,removing large rocks by hand and panning out gravel and sand, as you remove material from your pan your left with the heavier material (normally sand and your lead and any gold, keep panning you will pan off the lighter sand leaving black sand and your lead and gold, now carefully pan this black sand off, you will be left with your six pieces of lead and any gold if involved (any pyrite or iron ore has been panned off long ago, if you cannot pan everything off leaving just those six pieces of lead (and any gold), you need more practice panning, to practice re-pan that tub full of rock gravel and sand to recover your lead and get the gold you dumped out of your pan.

From your description at this point it sounds like you have fools gold.

There are several chemical tests you can use to test both iron solutions or gold solutions you will find them here on the forum (I have made several posts on this topic as well have many other members, but you cannot improvise these test as it sounds like you have been trying to do.

You can also find how to test for gold or iron in solution by reading Hokes book.

ok... I don't think I explained myself properly.

the panning was only on sub 600um particles.

the flakes are only about 50-100um. they are flat not crystalline (therefore not pyrite) and they are still there sitting in the AP bath.

the acid reduction assay I did was testing for the presence of iron oxide with HCL (giving me iron chloride salt), pyrite and mica. according to my research the HCL will chemically reduce the rubbish and not touch the gold.

I did this and the shiny flakes remained in suspension.

I was only asking about the colour change in the AP as I am not familiar with this process outside of stripping copper pins.

my initial thought was that the HCL had dissolved the fine iron oxide dust and caused the red colour. if this is true then I have my answer.

in regards to Hokes' book, I have read it (although I probably don't remember everything) and the majority of the chemical assays require chemicals and equipment that I don't have at home. (my lab is perfectly stocked but its probably frowned upon if I bring this stuff to work).

the acid assay is just an initial step to let me know if I have fools gold and/or mica (at least until I learn to know the difference visually)

hopefully that cleared a few things up.

 

[butcher]

Iron pyrite comes in many shapes, colors, sizes,and even composition, pyrite even forms in flat flakes when you crush these flakes with your thumbnail do they smash like gold or flake apart like pyrite, are the heavy in the pan of float around easily.

Do they melt to a lump of gold , or do you smell a lot of sulfur gases coming from them, and get a brittle lump of iron slag (do not stick your nose in them some pyrite can evolve arsenic gases which can be deadly).

You may have a hard time breaking the sulfide bond of pyrite with HCl (especially without roasting off the sulfides, and if this is an arsenate sulfide iron ore the gases can get dangerous either roasting or in acids.

You state "according to my research the HCL will chemically reduce the rubbish and not touch the gold." this is not necessarily true. with pretreatments you may be able to put some iron in solution, but just treating it with HCl will most likely not chemically reduce all the rubbish and not touch gold.

Iron in solution can form several colors depending on the oxidation and state of the iron, colors can range from a yellow solution that look just like our gold chloride solutions, to a green or dark brown even a black, browns or red of oxides and hydroxides can also form, colors are not much help here, this is why I pointed you towards Hokes book, she will describe how to test for gold or iron in solution.
There are several tests you can try, but if you do not get the chemical needed or follow the process needed, it would be hard to determine what the color of the solution was from.