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Techniques for CollectorsRemoving arsenic from native silver

3rd Feb 2015 22:34 UTCEd Clopton 🌟 Expert

How do people etch dendritic native silver out of native arsenic or stibarsen? Is there a safe, environmentally responsible way to do it, or is it one of those things we are happier not knowing?

4th Feb 2015 00:31 UTCReiner Mielke Expert

See this thread http://www.mindat.org/forum.php?read,62,330348,331249#msg-331249 Uwe Ludig's post.

4th Feb 2015 01:56 UTCDoug Daniels

Well, however you do it, a "safe, environmentally responsible way"...... You are dissolving the arsenic. What do you do with that solution (sounding like the late Carl Malden)....what do you do? And, I don't think that thread ever really defined what concentrations of the various compounds to use (I think that hydrogen peroxide is a max of 28%, but I am often wrong). Just don't let the EPA know you're doing it.

4th Feb 2015 09:53 UTCPaul De Bondt Manager

And do it in a " Bain-Marie " as reactions can be VERY strong.

I used to clean a rock with it and the generated heat melted my plastic recepient.

I hope this helps.

Paul.

4th Feb 2015 16:25 UTCReiner Mielke Expert

See: http://www.h2o2.com/industrial/applications.aspx?pid=108&name=Arsenic-Removal The scorodite that is produced as a precipitate can be safely disposed of in the garbage.

4th Feb 2015 21:19 UTCSteve Hardinger 🌟 Expert

Reiner, that may be true where you live. However here in California we give a damn about the environment, and don't just toss arsenates and related toxic waste into the trash.

The residue generated by hydrogen peroxide etching of arsenic is hazardous waste, and must be disposed of in a safe, legal, and ethical way.

It is because some people will dump anything down the drain that I don't discuss cleaning procedures that generate hazardous waste with most people. I refuse to arm them with the knowledge to pollute the world.

4th Feb 2015 22:04 UTCAlfredo Petrov Manager

True in some cases, but I wouldn't call scorodite "toxic waste"... There are mountains of it in nature, exposed to the elements, and it doesn't dissolve - very little mobility.

One could argue that by removing native arsenic from the natural environment and turning into scorodite, one has actually made the environment much less toxic than it was before.

5th Feb 2015 00:20 UTCReiner Mielke Expert

Changing dissolved arsenic to scorodite is the recommended way of disposing of arsenic waste and is approved by the Ministry of the environment here in Ontario and probably also in the US. In fact it is the only way to safely get rid of arsenic.

5th Feb 2015 17:15 UTCEd Clopton 🌟 Expert

The ultimate safety of this method of disposal may depend on how one's trash is disposed of. If it is landfilled, then locking up the arsenic in a relatively insoluble form such as scorodite would be o.k. If it is incinerated to generate electricity, as much of ours is here in southern Maine, then the scorodite probably would be converted to other compounds by the fire, releasing the arsenic into the atmosphere (not good) and/or contributing to the toxicity of the ash, which is a disposal problem in its own right but at least is already recognized and handled as such.

5th Feb 2015 17:34 UTCReiner Mielke Expert

Yes incinerating is not good however I would assume they have good scrubbers on them otherwise it is not good for anything period.

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