Non-Chemical Help.. SMB Precipt melt/smelt problem..brown glass goo

[rhwhite67]

Harold, Steve, Butcher, Irons, Noxx, anyone, please help.

I used the standard 4 parts (muratic)HCL / 1 part Cl leach with an added NACL solution mix and H2O to leach the gold out of a known gold ore of 6 oz to the ton.

The solution was a beautiful golden slightly reddish yellow and tested dark purple with stannous.

I filtered the solution, adjusted the ph to 3-4 and then used SMB/sodium bisulfate to drop the AU which came down/precipitated as a light to dark milk chocolate brown colored precipitant which clumped up nicely upon drying just as shown in the tutorials and Steve's videos.

I place the precipitant in a clay crucible and soaked it with an alcohol/borax mix to make sure that the precipitant had a good mix of borax in it when the alcohol evaporated. I then topped this mix with 1/4 inch of borax and fired it in my assay oven to 2150 degrees F for several hours until the melt swirled cleanly.

I then poured the melt which should have been a gold button on the bottom and a borax cap.

Here is the part i need help with as i have not had this happen before.

What poured was a borax cap and a brown goo/glass mix that looked just like/was the same color as the brown mud/precipitant bound up in the glass and no gold which should have been there. Not sure what went wrong as the gold precipitant did not seem to collect/fire down into a button as it should have.

I realize I will have to remelt this batch.

What is the best way to recover the gold in this melt.

Should I use a standard smelting flux of borax, soda ash, silica and flour or other reducer flux in a graphite crucible.

A long time friend who has done a lot of assay and metallurgy work over the years has suggested remelting with as silver oxide , borax, soda ash mix using the silver as a collector for the gold. However this would then require using nitric to separate the Silver from the AU.

Also what would you suggest doing to avoid this problem in the future.

This is frustrating because I currently have 10 lbs of this precipitant ready to fire and do not wish to lose this metal.

Please forgive me if I posted this in the wrong area. Any help will be greatly appreciated.

Thanks
Ron

 

[shyknee]

did you say sulfate or sulfite :?:
if sulfate then i hope you did not throw out the leach after trying to precipitate :?:

 

[rhwhite67]

shyknee

it is sodium bisulfate that is used and no i did not discard the solution. I always neutralize the solutions by adding sodium hydroxide until i get a neutral ph of 7 and i also collect all of that precipitate that drops out of solution as well. Is that what you were getting at , that there may still be more AU in the solution. I check everything with stannus chloride before discarding anything.

Thanks
Ron

 

[Barren Realms 007]

shyknee

it is sodium bisulfate that is used and no i did not discard the solution. I always neutralize the solutions by adding sodium hydroxide until i get a neutral ph of 7 and i also collect all of that precipitate that drops out of solution as well. Is that what you were getting at , that there may still be more AU in the solution. I check everything with stannus chloride before discarding anything.

Thanks
Ron

You are supposed to be using sulfite not sulfate.

 

[rhwhite67]

Thank you I realize this now what can i do in this situtaion? Ron

 

[lazersteve]

Precipitate everything with Al, Cu, or Fe and start over on the residues.

Treat the solid residue with HCl, water wash, and then AR to dissolve the gold.

Steve

 

[Harold_V]

I have long maintained that gold that is pure needs no flux. There is no question that the use of too much can prove troublesome.
I'm puzzled by your results, however. I would have expected that in a worse case scenario, you'd have some prills, along with a substantial amount of gold in the resulting slag. That doesn't appear to be the case. Can you describe the slag when it was poured? Was it thin, or viscous?

Are you certain you are achieving the desired temperature? I know it's a long shot, but if you aren't achieving the melting point, I can see how the miniscule particles of gold might be absorbed by the flux. I'm having more than a small problem with the idea that none of it agglomerated to form prills, although not getting hot enough might address that issue.

Did you overlook a washing procedure before melting the precipitated gold? I'm not suggesting that is the problem, but it may have contributed to the end result. A picture of the slag might serve some useful purpose.

Before you do anything else with the slag, you might consider melting it with an equal amount of soda ash to see what results. Make sure you're achieving the desired temperature. That can, amazingly, create metal when none is present, at least that can be identified. That's the process I used to use in cleaning very dirty melting dishes (using a torch). Always ended up with a button.

Harold