Fluxing E-waste with sulphur

[Ayham Hafez]

I started this discussion in another thread but I think it worth to be discussed in separate thread.

I will start from Jason videos links





In above videos we will see that sulphur added as a flux for E-waste smelting to sulphurize base metals, and he did different experiments with different fluxes recipe, as a conclusion it shows that sulphur very easy controls the base metals content in the E-waste expect tin!

Friend of mine advised me to use sulphur before I Know about those videos but maybe he got the idea from them, anyway I did an experiment with coax gold plated connectors that most of their weight is copper, I added 10% from their weight sulphur and at the end I got about 50% of the copper weight into the matt, sulphide matt, which I Know that I can recover the copper from it very easy by milling and roasting it or as Jason mentioned to smelt them with adding some iron.

@Yggdrasil wondered how sulphur not burned or evaporated before it combined with base metals since sulphur burned and evaporated in very low temperature? Really I don't know, what I know from my experience increases the wondering about this point, cause from my experience we roast gold ore to evaporate and reduce sulphur content, in the other hand, when I make tests in the past on recycling acid batteries, I tried to decrease the needed iron to reduce the smelting cost by heating the acid batteries paste that has lead sulphate PbSO4 in the rotary furnace before increase the temperature and start melt the lead but I failed, I noticed that there is no way to reduce lead sulphate into lead element without iron, so sulphur not evaporated by heating or roasting. (I didn't roast galena ore which has PbS not PbSO4 to see if sulphur evaporated from it by roasting)


If really sulphur do its magic as I noticed from my small experiment and from Jason videos, i think it will be the best way for recovering precious metals from E-waste, much more faster and affordable than even use copper electrolysis refining cell.

Hope someone in the forum have experience with it, I always be afraid from easy methods, sulphur makes precious metals recovering from e-waste really easy , so I'm trying to know if there any issues with using sulphur, and why tin not sulphurized as shown in the videos.

 

[Martijn]

@Yggdrasil wondered how sulphur not burned or evaporated before it combined with base metals since sulphur burned and evaporated in very low temperature?

Because it's mixed with or dissolved in the flux, so kind of trapped and reacting with iron.
I think he is using sulpur to oxidize base metals that are carried off in the slag, like with e-waste, and he uses iron when he's smelting sulfides, aka black sands from the number 2 and 3 concentrates, to have something for the released sulfur to react to, preventing to much sulfur going up in smoke.

 

[Ayham Hafez]

Because it's mixed with or dissolved in the flux, so kind of trapped and reacting with iron.
I think he is using sulpur to oxidize base metals that are carried off in the slag, like with e-waste, and he uses iron when he's smelting sulfides, aka black sands from the number 2 and 3 concentrates, to have something for the released sulfur to react to, preventing to much sulfur going up in smoke.

I think you alright, sulphur trapping with other fluxes prevent it from evaporating, with my 10% sulphur experiment I didn't smell too much sulphur, I added 430 grams of sulphur to 4300 grams of caox plated connectors, and I got same amount of gold that usually I get using same material with hydrometallurgy process.

So till now there is no cons with using sulphur.

 

[Ayham Hafez]

@4metals @kurtak

Could you advise please?

 

[4metals]

The sulfur will stink like rotten eggs for sure plus I have found in smelting forming a matt or speiss layer traps precious metals mechanically. If you found you can only get 50% of the copper out that means you left 50% behind along with the tin.

Oxygen sparging will leave all of the copper in the melt and will oxidize base metals and tin leaving a high percentage of copper containing all of your precious metals. This copper is perfect anode material for a copper sulfate cell and as a side benefit produces high purity copper.

The electrolytic copper cell has been around for many years and all of the kinks are worked out of it. I would embrace the proven until you grow to the size where switching over, if it is even worth it, pays for itself. While adding sulfur to a dirty melt may be useful under the right circumstances I cannot imagine it unless it is at very large scale where the exhaust is scrubbed efficiently. And it will be easy for the authorities to find you, all they have to do is follow the rotten egg smell trail to your door.

 

[Ayham Hafez]

The sulfur will stink like rotten eggs for sure plus I have found in smelting forming a matt or speiss layer traps precious metals mechanically. If you found you can only get 50% of the copper out that means you left 50% behind along with the tin.

Oxygen sparging will leave all of the copper in the melt and will oxidize base metals and tin leaving a high percentage of copper containing all of your precious metals. This copper is perfect anode material for a copper sulfate cell and as a side benefit produces high purity copper.

The electrolytic copper cell has been around for many years and all of the kinks are worked out of it. I would embrace the proven until you grow to the size where switching over, if it is even worth it, pays for itself. While adding sulfur to a dirty melt may be useful under the right circumstances I cannot imagine it unless it is at very large scale where the exhaust is scrubbed efficiently. And it will be easy for the authorities to find you, all they have to do is follow the rotten egg smell trail to your door.

Really appreciated, since I didn't find degassing tube in the market and potassium nitrate as well as sodium nitrate are forbidden in my country , I tried to find another way to push base metals into slags so I thought about sulphur.

Base metals even make issues with nitric acid parting not only copper cell so I must find solution, recently I found calcium nitrate fertilizer but didn't find any information about it in internet if it can work as a flux and oxidize base metals or not.

 

[4metals]

The nitrates will add Oxygen to your smelt and help put base metals in the slag but I have also seen a simple borax and soda ash flux with oxygen bubbled through the melt do the same thing.
It all comes down to how much copper is in the melt and how high the concentrations of what you want to remove are.

 

[Ayham Hafez]

The nitrates will add Oxygen to your smelt and help put base metals in the slag but I have also seen a simple borax and soda ash flux with oxygen bubbled through the melt do the same thing.
It all comes down to how much copper is in the melt and how high the concentrations of what you want to remove are.

So does calcium nitrate add oxygen to the molten similar to potassium nitrate?

 

[4metals]

My concern will be the effect of the calcium. Yes it will release its oxygen but my concern is the calcium reacting with the high carbonate content in soda ash.

My concern, and maybe it is nothing, but calcium carbonate may trap values in the slag.
You may be making the slags into ore. Some testing may be needed.

 

[Ayham Hafez]

My concern will be the effect of the calcium. Yes it will release its oxygen but my concern is the calcium reacting with the high carbonate content in soda ash.

My concern, and maybe it is nothing, but calcium carbonate may trap values in the slag.
You may be making the slags into ore. Some testing may be needed.

Oh, I was willing to add calcium carbonate as a source of calcium oxide to get silicon in slag, Kurtak advised to add calcium oxide with silica to make silicon in the slag as a lime-glass, when I make some search I noticed that in glass industry they add calcium carbonate in the furnace then with some heat it will convert to calcium oxide, so their goal is to get calcium oxide from calcium carbonate.

 

[4metals]

Are you trying to remove silica or base metals from your feedstock? Making a glass slag is desirable in any melt as long as it is a thin fluid slag so as not to hold up values.

 

[Ayham Hafez]

Are you trying to remove silica or base metals from your feedstock? Making a glass slag is desirable in any melt as long as it is a thin fluid slag so as not to hold up values.

Regard adding calcium carbonate is for removing silicon from ic chips. Silica with calcium oxide will remove silicon from molten to avoid alloying silicon with copper and PM's as Kurtak advised in thread:

https://goldrefiningforum.com/threads/slagging-off-silicon.34511/




But the main discussion of this thread is about removing base metals from molten.