Electrochemistry Is there a way to use electrochemistry to process a slag ore

[amosfella]

I have an ore/slag that a friend is asking me to seperate for him. From what I can tell from the assay (it's total percentages are in chinese, not very helpful to me.... I'm trying to get a translation.) it's 65-75% of either lead or iron sulphate, and 10-15% of the metal not covered in the 65-75%. The rest is PGMs, AU, AG, and a few other rare earths and heavy metals.
Apparently, this stuff has an extremely high melting temp. I was told (have not seen) that a guy couldn't cut a piece off with an oxyacetaline torch. (that also being said, I don't know what kind of head or tip he had for that torch) I"m also told that the stuff is extremely resistant to shock, crushing, etc.
So, I was wondering, as acid could be prohibitively expensive, is there an electric parting cell that could be built to take the base metals away, and leave the more desirable metals?? I have spent a bunch of time on google, but I have not found a cell that will part iron from other metals. Now that could be because I don't know the correct terminology to call it. Does anyone have any ideas in this reguard??

 

[NobleMetalWorks]

I believe, and someone will come behind and correct me if I am wrong, the best way to process ore slag on a small scale is going to be to mill it, then roasting it (always roast ore before processing it further) then using whatever wet process is required for that type of ore (hydrometallurgy) to recover the values. Maybe an HCl/Cl leach???

Scott

 

[nickvc]

From the little I understand about ores PGMs are normaly associated with nickel just as gold and silver are with copper and silver with lead, I'm not saying that's written in stone, excuse the pun, but it's not usual to have them in an iron ore. The answer to your problem may be to look to recover and refine the iron and then the waste will be a more concentrated form of the values or a more treatable form of them. In honesty this does not seem a proposition for a hobby or home refiner but I could be wrong but it will come down to the economics of the setting up costs and running costs of the plant to achieve the desired results, the downside I believe will be the size and cost of the plant to recover the iron first and to cover the environmental hazards adequately to satisfy the laws covering the emissions.

 

[amosfella]

This slag is coming from a 1800's copper mine/refinery site. All the copper is gone. I don't know why iron is there, but it is... For some reason, I thought the major constituent was lead.
I guess I was looking at it as if I was processing 100-200 pounds of the raw slag a month, I would be making a nice penny. Are there ways to use cells to refine the PGM metals??

 

[Geraldo]

If this is a copper smelting slag, then it SHOULD be high in iron.

Old copper smelting would typically use a reverb furnace, fed with copper concentrate and flux (silica and lime). The furnace would typically be fired with gas burners or oil burners, directly into the smelting chamber. Depending on the ore, they might also add "poles", which are young trees stripped of bark.

The purposes of smelting are to:
1. partially oxidize the copper to produce Cu2S, copper sulfide, which would form a matte (a sticky but distinct layer in the furnace) and a bunch of SO2 gas
2. fully oxidize as much iron as possible to produce iron oxides, which would be absorbed into a slag layer (another distinct layer in the furnace). The fluxing agents would combine with the iron oxides to make the slag fluid and stable.

So, if this is smelting slag, it SHOULD have some copper (the smelting process isn't perfect), iron, silica and lime, and a bunch of other impurities.

The next stage would be converting, in which the copper is oxidized to produce copper metal, more SO2 gas, and a small slag layer. In older times, they would use rotary convertors - think of a cement mixer, except at 1200 degrees celsius. Air is blown in while the whole mess turns. At the end of conversion, we have impure copper metal which is tapped out and then purified further, and convertor slag, which contains residual iron and other impurities. I am skipping the various dusts that are produced that contain nasty things like arsenic, beryllium and such.

So - - if this is copper smelting slag, we would expect iron, silica, lime and minor amounts of other stuff (including copper). If this is convertor slag, we would again expect iron, silica, lime and again, a bunch of minor elements. Most of the gold would go with the copper metal, as will PGMs. Depending on their operating efficiency, they might lose silver, gold and a small fraction of PGMs to either smelting or convertor slags, or both.

You should get a proper assay done. XRF, AA or similar, to know what you are dealing with. Depending on mineralogy and smelting practice, this could contain a lot of undesirables like arsenic, antimony, tin, lead, zinc, beryllium, nickel and cobalt.

Best Regards, Geraldo

 

[Lino1406]

Although I am afraid it may be uneconomical
The technology would be in principle
pressing an anode from the material
put in an anode bag
electrolyse in acid bath containing FeSO4 with high current and low voltage
metals below the cut-off voltage go to the cathode
The more inert metals remain in the bag

 

[g_axelsson]

Although I am afraid it may be uneconomical
The technology would be in principle
pressing an anode from the material
put in an anode bag
electrolyse in acid bath containing FeSO4 with high current and low voltage
metals below the cut-off voltage go to the cathode
The more inert metals remain in the bag

That can only be done if the material is conducting electrical current. With slag I highly doubt it. You can't press an anode from silica (65-75% of the material).

Please, do a proper assay, either fire assay or XRF (X-Ray Fluorescence) on a crushed and well mixed sample. Then you will know if there is any values in the slag and how much.

XRD (X-Ray Diffraction) only gives matches against minerals and is really hard if not run at clean material. Slag is not clean material and largely amorphous which will make XRD even less reliable.

Göran

 

[Lino1406]

Of course! I forgot to mention checking
electronic conductivity and in case it is
not enough add metal or carbon before
pressing. Again, I speak in principle
the way is long enough before it becomes reality

 

[amosfella]

thanks for the advice. I'm trying to get a sample to get it sent for a xrf or fire assay.