Smelting

[Nountaineer]

You don't buy Fluorspar at Walmart.

You would be surprised when you go to walmart.com and see what is available
They have smelting refining supplies but mostly refining.

 

[Nountaineer]

Legend Mining - 5 pounds fluorspar for $17.50 - or 50 pounds for $76.88

https://www.lmine.com/index.php?mai...ult&search_in_description=1&keyword=fluorspar
they have most everything related to mining smelting assaying

it's the first place (but not the only place) I look when I need things

Kurt

 

[Nountaineer]

Thanks I ordered it from Legend Mining. I tried to order a smelting book, assay crucibles etc but ended with about $360 shipping so cancelled and just ordered the calcium fluoride and a spiral bound smelting book.

 

[4metals]

Chapmans book about smelting is an excellent book full of flux formulations and practical advice. Written for a non chemist. Legend has that book as well.

If you click on the link in Kurtaks post above the book is shown. Well worth the money.

 

[Nountaineer]

I ordered the one that is spiral bound and is called a Field Guide. It was on clearance for $.49 which is budget compatible.

 

[ChopperGreg]

Ok, I’m going to toss a weird one out for a flux idea…

While normally considered as a flux for aluminum, has anyone considered cryolite?

 

[goldshark]

I have never used it, mainly because I get good results from using Silica, Soda Ash, Litharge, Iron nails, Flour, and Fluorspar, if needed. But I am usually fluxing a Quartz sulphide combo for Au/Ag only. Cryolite should work fine for thinning, as it fires /fuses at a lower temperature, and is a neutral flux. Never tried it as an only flux, plus collector metal only. If that is what you mean. I haven't looked into purchasing it, any sources?

 

[kurtak]

Ok, I’m going to toss a weird one out for a flux idea…

While normally considered as a flux for aluminum, has anyone considered cryolite?

Cryolite is not a flux for aluminum - it is a flux for alumina - alumina is an oxide of aluminum - it is VERY hard (just under the hardness of diamonds) & VERY chemical & heat resistant

it occurs in nature as mineral corundum & is a man made ceramic - due to it's hardness & chemical/heat resistant properties is why it is used for abrasives (sandpaper, cut off/grinding wheels etc.) as well as armor (bullet proof) plating as well as the linings in chemical reaction vessels & MANY other applications where the hardness & chemical/heat resistant properties of ceramic are needed

Though it (ceramic/alumina) is VERY chemically resistant - both hydrofluoric (not hydrochloric) acid & sodium hydroxide will react with it so will etch large pieces of ceramic &/or dissolve it if it is ceramic powder --- in other words hydrofluoric acid & sodium hydroxide are both solvents for alumina/ceramic

In smelting - cryolite is used as flux to slag off (finely ground) ceramic because at the HIGH temps of smelting cyolite is also a solvent for alumina/ceramic thereby allowing the ceramic to be dissolved & slagged off in the HIGH temps of smelting --- which is why the BIG BOYS use cryolite for smelting CATs

I use it for smelting ceramic capacitors (after milling to fine powder) - BUT - because cryolite is a flux/solvent for ceramics in smelting it is also hard on (shortens life) of crucibles - so you want to use "good" quality crucibles & not cheap "budget" crucibles

to clarify - cryolite is a flux ingredient added to other fluxes - starting with the basic fluxes of borax & soda ash - plus other fluxes - based on what else is needed for the smelt (such as fluorspar, silica, carbon etc. etc.)

Like it doesn't take much fluorspar in you flux to thin slag - it doesn't take much cryolite in your flux to dissolve/slag off the ceramic --- as with all things smelting - it's a bit of a learning curve to figuring out how much &/or what flux ingredients are needed in the particular material you are smelting

Cryolite is also used as a glaze for making pottery so that is a source for where it get it

I have not tried this yet - but because cryolite works as a flux for ceramics I have thought about trying to use it as a flux for smelting black sands as it may (or not) also work for slagging off the iron oxides that make up black sands ???

Kurt

 

[Yggdrasil]

Ok, I’m going to toss a weird one out for a flux idea…

While normally considered as a flux for aluminum, has anyone considered cryolite?

I believe Cryolite and Flourspar are more or less interchangable.
Flourspar are easier to find I think.

 

[Yggdrasil]

Cryolite is not a flux for aluminum - it is a flux for alumina - alumina is an oxide of aluminum - it is VERY hard (just under the hardness of diamonds) & VERY chemical & heat resistant

it occurs in nature as mineral corundum & is a man made ceramic - due to it's hardness & chemical/heat resistant properties is why it is used for abrasives (sandpaper, cut off/grinding wheels etc.) as well as armor (bullet proof) plating as well as the linings in chemical reaction vessels & MANY other applications where the hardness & chemical/heat resistant properties of ceramic are needed

Though it (ceramic/alumina) is VERY chemically resistant - both hydrofluoric (not hydrochloric) acid & sodium hydroxide will react with it so will etch large pieces of ceramic &/or dissolve it if it is ceramic powder --- in other words hydrofluoric acid & sodium hydroxide are both solvents for alumina/ceramic

In smelting - cryolite is used as flux to slag off (finely ground) ceramic because at the HIGH temps of smelting cyolite is also a solvent for alumina/ceramic thereby allowing the ceramic to be dissolved & slagged off in the HIGH temps of smelting --- which is why the BIG BOYS use cryolite for smelting CATs

I use it for smelting ceramic capacitors (after milling to fine powder) - BUT - because cryolite is a flux/solvent for ceramics in smelting it is also hard on (shortens life) of crucibles - so you want to use "good" quality crucibles & not cheap "budget" crucibles

to clarify - cryolite is a flux ingredient added to other fluxes - starting with the basic fluxes of borax & soda ash - plus other fluxes - based on what else is needed for the smelt (such as fluorspar, silica, carbon etc. etc.)

Like it doesn't take much fluorspar in you flux to thin slag - it doesn't take much cryolite in your flux to dissolve/slag off the ceramic --- as with all things smelting - it's a bit of a learning curve to figuring out how much &/or what flux ingredients are needed in the particular material you are smelting

Cryolite is also used as a glaze for making pottery so that is a source for where it get it

I have not tried this yet - but because cryolite works as a flux for ceramics I have thought about trying to use it as a flux for smelting black sands as it may (or not) also work for slagging off the iron oxides that make up black sands ???

Kurt

If I’m not wrong the largest consumer of Crylite is the Aluminum producers.
They use it to melt the Alumina prior to the Electrolytic conversion to Aluminum.

 

[4metals]

Fluorspar is an easier to obtain version of cryolite. Both work similarly. Cryolite is a powdered form of a natural mineral, fluorspar is blended.

 

[kurtak]

Never tried it as an only flux,

Like it doesn't take much fluorspar in you flux to thin slag - it doesn't take much cryolite in your flux to dissolve/slag off the ceramic --- as with all things smelting - it's a bit of a learning curve to figuring out how much &/or what flux ingredients are needed in the particular material you are smelting

Now you know

any sources?

Cryolite is also used as a glaze for making pottery so that is a source for where it get it

Now you know

Kurt

 

[snoman701]

https://www.axner.com/cryolite.aspx

 

[snoman701]

Can anyone recommend a starter flux for use with electronic chip (plastic) ash, ground in a ball mill, to be melted with silver as a collector?

 

[kurtak]

Can anyone recommend a starter flux for use with electronic chip (plastic) ash, ground in a ball mill, to be melted with silver as a collector?

Soda ash (washing soda) borax & silica (& a bit of fluorspar if/as needed for thinning)

Start by mixing 50/50 borax & silica - then double that with soda ash

You need the silica because after milling the chips there will be a fair amount of fine silicon in the concentrates (from the milling of the silicon dies in the chips) --- silicon will alloy with gold - so the silica fuses with the silicon & allows the silicon to slag off

the reason for doubling the soda ash after mixing the 50/50 borax/silica is that with the extra soda ash you can mill the slag (to powder) & the slag will dissolve in HOT water allowing you recover any metal bead that get hung up in the slag

Kurt

 

[snoman701]

So 1 parts Borax:1 parts Silica: 4 part Soda Ash?

Equal parts of the above flux and the ash?

 

[kurtak]

Soda ash (washing soda) borax & silica (& a bit of fluorspar if/as needed for thinning)

Start by mixing 50/50 borax & silica - then double that with soda ash

You need the silica because after milling the chips there will be a fair amount of fine silicon in the concentrates (from the milling of the silicon dies in the chips) --- silicon will alloy with gold - so the silica fuses with the silicon & allows the silicon to slag off

the reason for doubling the soda ash after mixing the 50/50 borax/silica is that with the extra soda ash you can mill the slag (to powder) & the slag will dissolve in HOT water allowing you recover any metal bead that get hung up in the slag

Kurt

As an added note - if you are able to get your concentrates down to "at least" 30% gold bond wires (&/or more then 30%) you should not need a collector metal - especially if your slag runs nice & fluid/thin

Kurt

 

[snoman701]

See, when I've used that much carbonate, it just bubbles. I'm pretty sure it's eating the wall of the crucible.

 

[kurtak]

So 1 parts Borax:1 parts Silica: 4 part Soda Ash?

yes

Equal parts of the above flux and the ash?

Depends somewhat on how good you get your concentrates

If you get a good concentrate (at least 30% or more gold) equal parts flux to concentrate should be fine

more junk in the concentrate will mean more flux needed as the purpose of the flux is to slag off the junk

Kurt

 

[kurtak]

See, when I've used that much carbonate, it just bubbles. I'm pretty sure it's eating the wall of the crucible.

I will post a solution to that later - I need to get on to other things right now

Kurt