Slagging iron and manganese from orecon

[plasmasmelter]

I've got a metal button...well actually a metal blob that was created
in a reduced environment arc furnace. It is high in elemental Manganese and Iron
with some tin and traces of other metals including AU and PGM's. There may
be small amounts of sulfur also.

The metal "blob" weighs 22.5 kg and I am formulating an oxidizing and fluxing
recipe in hopes of oxidizing the base metals and fusing them into the flux
materials I will be adding. I also plan to use forced air to hasten oxidation of the
base metals. We are using a carbon arc electric furnace and a graphite/clay crucible.
I am researching the heat-time-flux-oxidation relationships now and will report back
with a recipe formula and plan of attack.

Question: Anybody have a clue as to how I should approach it?

PS

 

[qst42know]

Your arc torch is quite a beast. As cool as it is, have you considered you may need to change tactics to get some jobs done?

Heated dilute sulfuric should dissolve the iron and manganese.

 

[4metals]

A good oxidizing flux I've used is;

1 part sodium carbonate
1 part anhydrous borax
2.5 parts potassium nitrate
1 part silica

of course an intimate contact with the oxidizable metals is required, a pool of this flux at temperature will out gas without much effect on your charge. Air alone is a powerful oxidizer if you can get the molten metal rocking to expose more to the air.

 

[HAuCl4]

A good oxidizing flux I've used is;

1 part sodium carbonate
1 part anhydrous borax
2.5 parts potassium nitrate
1 part silica

of course an intimate contact with the oxidizable metals is required, a pool of this flux at temperature will out gas without much effect on your charge. Air alone is a powerful oxidizer if you can get the molten metal rocking to expose more to the air.

After looking at his photos: That manganese/ferrum piece must be extremely brittle and should crush to bits quite easily. Mix the appropiate amount of your suggested flux, and good things may start to happen. :idea:

edit: IMHO reducing all that much manganese dioxide to manganese is a mistake to begin with. A mild melt of the concentrates and flux at 800 C should get rid of most manganese dioxide as a near-barren slag, leaving a much cleaner button (with all the values) to oxidize.

Yet plasmasmelter did what he did and now has to clean up that blob of metal somehow. He basically used manganese as a "collector". I guess there is a first time for everything, and pretty sure he got 100% all the values out (that did not volatilize!). :lol:

 

[plasmasmelter]

Thank guys for the constructive criticism and help,

Quest4know,

Yes I am interested in wet refining. When we get something rolling we may get 4metals
to lend a hand. The book i ordered should give me a guide to more knowledge and see
how we can use it to our benefit. Will research that more here as well.


4metals,

Thank you for the help.
I like the flux recipe you cited. I plan to feed the crushed charge and flux
together while forcing air at the same time. Any idea how hot and how long
to hold the melt to get full oxidation and fusion?

HAUCL4,

Yes, I know we screwed up and should have slagged the oxides with the first
run instead of running in reduced furnace. We know better now.
I just ordered the book "Chemistry of Gold Extraction" by John O Marsden.

Any thoughts on melt temp and hold time? How about sequencing the oxidizer vs flux.
That may seem obvious, but I would like to get your thoughts on that issue.

Again much thanks for the support,
PS

 

[HAuCl4]

I'd start heating slowly and certainly not with an arc torch. Manganese melts at about 1,250 C and iron at about 1,500 C , but that flux will react and bubble with the charge at much lower temperatures. If you heat too fast the charge will boil out of the crucible.

You probably need to mix with flux, slag, mix with new flux, slag, etc a few times (without melting) to get rid of that amount of base metals and oxides. By the time you get to 1,000 C the bubbling and the reacting with the flux are probably gone, and you can slag. You must take samples of the slags to make sure they are barren of precious metals (save the slags too for future treatment). When you get a much smaller and concentrated button you can proceed with acid treatments.

Really take it one step at a time and post pics. I'm sure we'll all learn and we will try to give you suggestions.