Polishing dust melting help

[Bigmangold]

Hey guys,

Really appreciate some help.

I have a big bag of polishing “dust” which I have burnt and incinerated into a fine powder. (Mainly consists of high grade 18kt gold.)

Looking to melt this into a bar which then I can XRF and.

How should I do it. What’s the composition of the “flux” I’ve done allot of reading into mixing with borax and melting it? What temperature do I do it at and how and in what. I’ve got a 1kg electric furnace for melting normally jewellery.



Any advice or help is much appreciated. (I don’t want to chemically refine it yet)

Also want to do it myself as I’m not sure how much gold is in there over time - so don’t want to drop it to a refiner.



I tried melting a small bit of it directly in the furnace but it turned to a glassy piece of lava rock.

 

[4metals]

With a 1 kg electric furnace you will literally be there forever. Also consider that when you flux it the volume will double. A 1 kg furnace has a crucible that is about 1” diameter and 4”
Deep.

 

[Bigmangold]

With a 1 kg electric furnace you will literally be there forever. Also consider that when you flux it the volume will double. A 1 kg furnace has a crucible that is about 1” diameter and 4”
Deep.

What shall I use instead and what flux?

 

[4metals]

You will need a larger furnace for sure. A gas fired crucible furnace with at least a #10 crucible capacity. You will need to experiment with fluxes depending on what type of rouge was used to polish the jewelry and create the sweeps you burnt.

 

[snoman701]

Any advice or help is much appreciated. (I don’t want to chemically refine it yet)

Also want to do it myself as I’m not sure how much gold is in there over time - so don’t want to drop it to a refiner.



I tried melting a small bit of it directly in the furnace but it turned to a glassy piece of lava rock.

You'll be better off finding a good refiner. Polishings aren't good learning material, and trying to smelt them isn't straightforward.

I've done a fair amount of polishings by chemical leaching. I don't smelt them as it's considerably more work to get the same result you get from acid refining, and without the ability to do an assay on the tailings, you are still shooting blind.

 

[kurtak]

I’ve got a 1kg electric furnace for melting normally jewellery.

If it is this type electric furnace ------------

https://www.ebay.com/itm/2962012078...1291&msclkid=e073f301352115aa59ef96f93a01ba46

Then do not even try to use it for smelting or you will destroy the furnace in very short order

1) if you have a boil over of the flux (flux foams up over top of crucible) it will then run down the outside of the crucible & get on the heating elements inside the furnace & destroy the heating elements

2) the graphite crucibles made for those furnaces do not stand up to flux - the flux eats away at the graphite making the crucible very porous - the flux then bleeds through the crucible & gets on the heating elements inside the furnace & destroys them so the flux destroys both the crucible & heating elements

You will be lucky if the flux doesn't bleed through the crucible on the first smelt & it will for sure bleed through the crucible on a second smelt

Those furnaces are made for melting & NOT for smelting --- & IMO they are not all that good for melting

Kurt

 

[Rchrygy]

Hey guys,

Really appreciate some help.

I have a big bag of polishing “dust” which I have burnt and incinerated into a fine powder. (Mainly consists of high grade 18kt gold.)

Looking to melt this into a bar which then I can XRF and.

How should I do it. What’s the composition of the “flux” I’ve done allot of reading into mixing with borax and melting it? What temperature do I do it at and how and in what. I’ve got a 1kg electric furnace for melting normally jewellery.



Any advice or help is much appreciated. (I don’t want to chemically refine it yet)

Also want to do it myself as I’m not sure how much gold is in there over time - so don’t want to drop it to a refiner.



I tried melting a small bit of it directly in the furnace but it turned to a glassy piece of lava rock.

I just refined about 10 lbs of buffing debris.....and I'm new at this. I incinerated it and ground and sifted it (I don't own a ball mill). Then I incrementally added Nitric acid substitute to the quantity of ash I was refining, stirring frequently, and strained off the solids after boiling off the brown gas. I even reboiled the solids once more until I detected no more precious metal . I recovered the gold from the liquids with SMB and am fairly certain that I got all the gold I could.
Chemical refining is not a bad way to go if you are prudent about your processes, l.e. masks, adequate ventilation, rubber gloves, proper procedures.

 

[Yggdrasil]

I just refined about 10 lbs of buffing debris.....and I'm new at this. I incinerated it and ground and sifted it (I don't own a ball mill). Then I incrementally added Nitric acid substitute to the quantity of ash I was refining, stirring frequently, and strained off the solids after boiling off the brown gas. I even reboiled the solids once more until I detected no more precious metal . I recovered the gold from the liquids with SMB and am fairly certain that I got all the gold I could.
Chemical refining is not a bad way to go if you are prudent about your processes, l.e. masks, adequate ventilation, rubber gloves, proper procedures.

Nitric acid substitute or Nitric will not dissolve Gold alone.

 

[Rchrygy]

Nitric acid substitute or Nitric will not dissolve Gold alone.

You are absolutely correct! I neglected to insert that I used the nitric acid substitute with HCL. My omission and apologies!

 

[Yggdrasil]

You are absolutely correct! I neglected to insert that I used the nitric acid substitute with HCL. My omission and apologies!

Then we have poor mans AR