Properly botched job

[Topher_osAUrus]

8)

Copperas (ferrous sulphate) is actually a pretty good precipitant for dirty solutions. But, I would still say if its a really dirty solution just cement with copper... That way you arent increasing the bulk of the waste solution (copperas requires dissolving in water, then adding hcl to it, er'go adding to waste) but if you feel you need to ppt instead of cement from dirty solutions its good to use copperas for the first precipitation, then smb for the second. As each has their own unique contaminant possibilities. Using each one for each of the purification steps helps cut down the contaminants and end up with pure gold.

You want to go the extra mile and be a try hard, do the third precipitation with oxalic acid and get it really beautiful!

 

[jeneje]

There are a few things one needs before starting to refine. Let's take a look at them.

• 1). Your standardized test solutions.
  (Gold standard, Platinum standard and of course Palladium standard).
  2). Then, you need your test solution, Stannous Chloride and DMG at a bare minimum.
  3). Then, one must have the never fail go to - A Copper bus bar for all those i had gold days and can't find it. :lol:
  4). And then, as been mentioned, the almighty stockpot for your retirement :shock: .
  5). When you are still lost and are scratching your head, saying where is my gold? Break out the old Hoke's book and start at chapter-one.

I am sure I missed a few finer points but, hell it's late and time for bed. :wink:

Good luck,
Ken

 

[Geo]

I agree with Ken. Obtain some 18K scrap and dissolve a gram in 30mls of solution. This will be your test standard. You use it to test your stannous chloride against it to make sure your stannous chloride is still good. Stannous chloride is very sensitive to precious metals in solution. It can detect minute amounts of gold in solution. When you do it enough, you can even gauge the amount of gold in the solution according to the test results. To acquaint your self with it, use your test standard and dilute small one drop samples with fresh HCl to test. That way you can see how much of a stain is left by a very diluted samples.

Your test looks like a negative. If you are sure that all metal dissolved, look at what's left of the material to make sure, there is still too much solution to get a good, positive test. You may have to evaporate what you have again by half. And again and again until the gold shows with stannous chloride. Also, dissolve some known gold metal to test your stannous chloride against.

 

[aga]

Thanks for the tips Topher, jeneje and Geo.

A Stock pot sounds like a good plan.

Currently i'm 'processing' just this one old PC, so there will be no further wastes to be handled in the immediate future (sounds like everyone's famous last words !).

For precipitation there is SMB and iron (II) sulphate on hand, but no oxalic acid. There is some pure vitamin C which i understand can be used in some situations, but do not know which. Ditto fructose.

I guess having a Standardised test solution is the best/only way to test the stannous chloride.

If/when any metal gets coaxed out of this Mess, making a chart of the appearance of the SC test with increasing dilutions of some AR-dissolved bought/authenticated gold will be a good exercise.

DMG does not seem to be easily available as crystals (ebay).

I think everyone will agree that Hoke's refining book should be swapped from #5 to #1 :wink:

 

[g_axelsson]

Since you like experimenting, doing the acquaintance tests in Hoke could be a good exercise. There also is a lot of similar experiments in her second book, Testing precious metals.

My acids are technical grade concentrated, HCl at 30-35% and nitric at 70% but I usually dilute the acids to save on them and cut down fumes. It means that reactions can take a longer time, but I'm seldom in a hurry.

Göran

 

[anachronism]

As Goran said. FYI "not being in a hurry" really really works in this game.....

 

[aga]

Thanks for the information guys - calculating the amount of nitric needed right now.

It's already been 2 full days of solid work to get to a position where all of the original metals (hopefully) are in 1 pot. Turned out that the pot is too small so had to go for 2 pots

It's almost at the stage where the base metals can be removed and the gold extraction begins.

Should be able to get there sometime tomorrow morning.

If so, i'll proceed all the way to the melt - if there is anything to melt !

Full details tomorrow with any luck, including whether it ends a success or a failure, also photos of the whole sorry tale.

Oh ! Even if any gold happens, there's the refining to do, twice, if there's enough gold for that ...

 

[upcyclist]

Speaking of patience, nitric, and stockpots/cementing: Be sure to use lots of agitation (an aquarium bubbler will work) and time when you're cementing. Cementing will be harder with metastannic acid and silver chloride mucking everything up.

Oh yeah, since you applied AR to everything, your silver is likely in the muck, too, as silver chloride. Edit to add: and silver chloride is essentially insoluble in nitric and hydrochloric acids.

--Eric

 

[aga]

After many days of fruitless effort, i could not recover the gold.

Right now, all the liquids are in a 'stock pot' with some copper pipe and a bubbler.

Well, when all else fails. Stock pot it.

Change that to "Before pointless efforts fail, Stock pot it."

The notes are long, tedious and depressing. A full write-up would be more so.

In brief, here's what i tried, and how i failed :-

1. Yellow liquid only :-
Evaporate down to 15%. Metastanic goop. Add water, heat/stir to re-dissolve. Drop gold with SMB.
Fizzed too much due to xs acid. Added sulphamic. Pot fizzed over. Lost 50% of volume.

2. Blue/green liquids :-
Neutralise acids with sodium bicarbonate. Filter, saving filtrate. Put all papers/solids in a stainless steel pot and pyrolyse, then incinerate.
Pot contents ended up a solid block. Break up, wash out, dry, weigh, add calculated 650g nitric to remove more copper. More fizzing, overspill (again).
Days of just filtering/drying/evaporating 3 litres of liquid.
Resulting solids dried, weighed, calculated volume AR added, HNO3 in portions, left overnight/all next day, stirring/warming.
Filtrate very dark green.
Accept failure, rig up a stock pot and dump the lot in there.


The Lesson is basically to do what more experienced people tell you do.
Saves a lot of wasted time and effort.

 

[jeneje]

It is always better to deal with Metastannic acid (goop) as you call it early on in the process. Once you have created it, the best way I have found is to incinerate the Metastannic acid using red heat and then dissolve in HCl to remove it, leaving your gold foils or ? ever.

Hope this helps you next time you run into it.

Ken

 

[g_axelsson]

Told you so! :mrgreen:

Göran

 

[aga]

Told you so! :mrgreen:

Yep, and you were Right because you Knew !

Having wasted so much time & effort, i'll never ever go down a random path to try to recover/refine any PMs.

It hasn't be a lot of fun, but it has been a Lesson well and truly learned :
No messing about, just follow a tried and trusted procedure if a good result is required.

Next up is to recover any gold from the stock pot as-per Hoke's instructions in chapter XIII.

I was thinking a week should be enough time to leave it bubbling.

If anyone recommends longer, then it will be left for a longer time.

 

[aga]

Some photos of the whole sorry business :-

 

[Topher_osAUrus]

A
Evaporate down to 15%. Metastanic goop. Add water, heat/stir to re-dissolve. Drop gold with SMB.
Fizzed too much due to xs acid. Added sulphamic. Pot fizzed over. Lost 50% of volume.

Was the solution still hot when you added the smb? I rarely have the solution effervesce so violently...but, I always have my solution cold when adding smb...and I always try to have the nitric out of solution. Either by killing it with heat, sulfamic, or evaporating

2. Blue/green liquids :-
Neutralise acids with sodium bicarbonate. Filter, saving filtrate. Put all papers/solids in a stainless steel pot and pyrolyse, then incinerate.
Pot contents ended up a solid block. Break up, wash out, dry, weigh, add calculated 650g nitric to remove more copper. More fizzing, overspill (again).
Days of just filtering/drying/evaporating 3 litres of liquid.
Resulting solids dried, weighed, calculated volume AR added, HNO3 in portions, left overnight/all next day, stirring/warming.
Filtrate very dark green.

Did this filtrate test positive with stannous? Were there more undissolved solids still?..The amount of gold from this may be next to none, but still, it should be *somewhere*
Accept failure, rig up a stock pot and dump the lot in there.

Did you neutralize to 7? or..? the stock pot needs to be acidic..Hoke says to just add a bit of HCl

The Lesson is basically to do what more experienced people tell you do.
Saves a lot of wasted time and effort.

Don't feel too bad, I think everyone here has tried to cut a corner or two at one point in time. I was cutting corners left and right when I started "refining"...but the school of youtube wasn't the best place to find out the best practices ....eventually I found the GRF and was dumbfounded by how much I didn't know...

edit to add: disregard that neutralize to 7 question. I realize now, that you were speaking of the material that you pyrolized and incinerated not the solution you threw in the stockpot.

 

[aga]

Was the solution still hot when you added the smb?

Umm, yes

Lots of fizzing when adding SMB, plus some NOx fumes. Adding less than a pea-sized amount of sulphamic acid fizzed it out of the pot. Shame, as that pot was the only one concentrated enough to give a result with SC.

Did you neutralize to 7? or..? the stock pot needs to be acidic..Hoke says to just add a bit of HCl

I will check the pH today, also re-read the 'Stock Pot' chapter and make notes before touching anything !

 

[upcyclist]

It is always better to deal with Metastannic acid (goop) as you call it early on in the process. Once you have created it, the best way I have found is to incinerate the Metastannic acid using red heat and then dissolve in HCl to remove it, leaving your gold foils or ? ever.

Hope this helps you next time you run into it.

I caught early on that I don't need to run HCl-only solutions through my stockpot, but I got some metastannic acid in my stockpot even earlier than that. I also realized a little too late that I should run a separate stockpot for silver nitrate.--now I have both metastannic acid (some) and silver chloride (lots) in my stockpot.

Should I try to convert the AgCl before I incinerate for metastannic? There's still a fair amount of copper solids in there, but we're talking about a liter of solids at the bottom of the stockpot. It's mostly silver, and I don't want to find out that incineration is a good way to lose all the silver. Thoughts?

 

[Topher_osAUrus]

I caught early on that I don't need to run HCl-only solutions through my stockpot, but I got some metastannic acid in my stockpot even earlier than that. I also realized a little too late that I should run a separate stockpot for silver nitrate.--now I have both metastannic acid (some) and silver chloride (lots) in my stockpot.

Should I try to convert the AgCl before I incinerate for metastannic? There's still a fair amount of copper solids in there, but we're talking about a liter of solids at the bottom of the stockpot. It's mostly silver, and I don't want to find out that incineration is a good way to lose all the silver. Thoughts?

I stockpot my HCl solutions that i rinse powder gold with, or if they arent "dirty" after that, I use it for the recovery AR dissolution of gold, then fresh HCl for the refining stages.
It is suggested to keep AgCl wet since it becomes difficult to get a full conversion when its dry -especially if its chunky.
If its just a wee bit of tin sludge, you may just want to go ahead and convert the AgCl. Accepting the small amount of impurity the tin will add, removing it at a later refining stage.
...i think that would be better than drying out and crusting up your AgCl
Hoke says that metastannic is soluble in sulfuric, and of course AgCl is not... But, my experiments with that have shown the tin sludge isnt *truly* soluble in it, it just becomes colloidal almost, and will settle out if given ample time.

So maybe it's just best to convert it with dilute sulfuric and iron and go from there..

Or maybe convert with NaOH then rinse and dissolve in nitric. Leaving the tin sludge behind. Of course your copper bits would go in solution with it, but the tin would be able to be filtered off.(slowly!)

 

[upcyclist]

Thanks--I needed a sanity check on that. I didn't mention it earlier, but yeah, I'd pull out the copper first as well as re-refine the silver (depending on how clean it looks, save it for a cell or run through nitric again). I'll incinerate whatever's left after the conversion (I too prefer sulfuric & iron), since there should also be gold in there.

I didn't mean gold-rinsing HCl, btw--I was referring to HCl soaks & polluted CuCl₂/__Cl_x used for removing base metals.

 

[Topher_osAUrus]

Thanks--I needed a sanity check on that. I didn't mention it earlier, but yeah, I'd pull out the copper first as well as re-refine the silver (depending on how clean it looks, save it for a cell or run through nitric again). I'll incinerate whatever's left after the conversion (I too prefer sulfuric & iron), since there should also be gold in there.

I didn't mean gold-rinsing HCl, btw--I was referring to HCl soaks & polluted CuCl₂/__Cl_x used for removing base metals.

Im with you now, and agree. Sulfuric/iron is quick and easy... But, i like hcl/zinc for agcl crust on goldfilled material.. I had very good luck recovering silver and gold with that method. (I had it caught in filter papers, so i didn't want the sulfuric to make a mess of them)