Kevin,

Some people have used TBP (Tributylphosphate) to remove arsenic. Read the following paper for details:

 http://www.sciencedirect.com/science/article/pii/0008443395000445

http://onlinelibrary.wiley.com/doi/10.1002/jctb.843/abstract

I am not aware of any companies which directly extract arsenic from copper pregnant leach solutions during purification steps using SX

Regards,

Alex

Alex,  thanks for your help.

As far as you're concerned, commonly how did they remove arsenic in industrial production?

Thanks！

Sorry, its a little complicated but lets try.

Generally speaking a part of arsenic which is included in copper concentrate goes to dusts and slimes during a proces of off-gases cleaning in smelter. Next, those dusts and slimes are smelted (in order to produce Pb),  and arsenic is separated.

The other part of arsenic goes with copper to electrolite at electrorefining stage, where final copper cathodes are produced . After some time of electrorefining, concentrations of specific for a given smelter elements (e.g. Fe, Ni, As, Sb and Co  in KGHM Polish Copper smelter) in electrolite increase to a level, which causes unwanted increase of admixtures in final cathode copper (and other unwanted effects). When electrolite solution is dirty enough it is drawn from electrolite circuit and is directed to so called decopperizing proces. At first, dirty electrolite solution is neutralised  by reaction of sulfuric acid (which is contained in electrolite), metallic copper and oxygen). After neutralization, copper sulfate is cristallized and removed. Such purified solution is directed to electrowinning. A product of the electrowinning is dirty cathode copper, which must be returned to anode furnaces, because of high content of arsenic. Melted copper from flash smelting proces and dirty cathode copper in anode furnace is oxidized  in order to remove unwanted admixtures, During this period sodium carbonate and CaO are added to meltedcopper.

I did not "investigate" if arsenic is separated by EX, but I nevee hard about such proces also.

Regards,

Andrzej    

Noranda (now Glencore) developed an SX process (US Patent 4,115,512 - 1978) which was never implemented.  However, Copper refiners in Townsville did operate such a process (see paper referenced above), but only so long as they were able to sell copper arsenate as a wood preservative.  Noranda also developed the PCR (Periodic Current Reversal) process for their refinery, which they did implement, and which still operates today.  

You do have to know what valence state your arsenic is in to implement any successful strategy.  If you are doing electrowinning rather than refining, which implies a preceding leach circuit, then you should be able to adjust the leach circuit to precipitate most of the arsenic when you eliminate the iron.

Andrezej,

Yes, we barely hear that process.

But now Bryn Harris tell us some information. Maybe we can know more from his comments.

Kevin - I am afraid I cannot tell you more than is in the patent I cited, and in the paper referred to by Alex.  As always, you have to try it out in the lab.  But as I say, if this is a leach process, why is the arsenic not being separated with the iron?

Kevin,

May be I should explain that in our days nobody wants arsenic. Even Noranda closed As extraction because demand for As dramatically droppeed down and probably remove As as others. If you still need more information about As EX, the only way is to look at the US patent, reccomended by Bryn. 25 years have passed so you can use it.  I also would like to confirm Bryn`s opinion  that if you have leaching the best moment for deailing with arsenic is leaching. Additionally, PCR proces help you to produce better copper but you will still have problem with As management.

I suggest you precipitate it up front with Na2S solution and separate (e.g. filter)

Precipitation with Na2S would not work since copper would precipitate as CuS!

It does work, but as you say, copper also comes down - as Cu2S not CuS.  It is also a VERY messy process If there is ferric iron present, this will get reduced, thus greatly increasing reagent consumption.

The composition lies between CuS and Cu2S 

http://www.sciencedirect.com/science/article/pii/S0304386X10001775

Andrzej,

yes, I found that NaOH-Na2S leaching  process can pre-treat the copper ore containing arsenic, according to the papers I read, this process can effectively remove the arsenic. 

As management trully is a problem. Do you know any good way to manage them?

As preceipation and then buried? or recovery and produce arsenic products? 

Kevin,

As leaching is quite well known proces, used for Sb and As removal. But it was used in  a very limited number of plants (at least 1 concentrator! in USA and 1 smelter anywhere. I have no idea what`s situation is now.

Management. Of course the best way of As management is production of any market product. The problem is that demand for arsenic (and its compound) is very low. The current total production amounts to approx 45.000 ton As. Arsenic is used mainly for production of wood presevatives, herbicides, alloy component, electronics, and glass industry  Because of small market only in a limited number of cases you can sell your arsenic which you have to produce because of ennvironmental law. Arsenic is produced mailny in copper but also in gold and cobalt smelters or hydrometallurgical plants. If they are not able to sell final As product  they have to disposal it. The fundamentl requirement is to produce as stable As compound as possible. Usually it is scorodite (FeAsO4x2H2O), calcium arsenate or sulfide As.

Andrzej

Yes, I agree with you.

The best way is to recycle and produce As product. 

However, the As product market is small and limited. 

So that's incompatible with the high As production, because of As's wide existence.

For example, many mines in South America contain high arsenic.  

In the future, whether there will occur a good method to treat and use As is worth expecting.

Another more common trouble in copper L-SX-EW plant,  content of Si control.

Are you once involved in this trouble?

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