Metal finishing Q&As since 1989

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Is GPC an air pollutant? What chemicals react or neutralize it?

I want to know if the GPC is airborne and if so how can it be neutralized using a wet scrubber.

Kalaimani s/o Samyvelu
plastic scrubber - Kuala Lumpur, Federal Territory, Malaysia
2003

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Unfortunately, I don't know what 'GPC' stands for. Gold potassium cyanide? Thanks.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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Hi Kalaimani

Ted doesn't know what GPC stands for ! He's l00% right. Just WHAT does it stand for? Galium Potassium Chromate?

I'm very interested to know ... especially as you mention a plastic scrubber ... and my background (see Australian finishing magazine) happens to be in plastic scrubbers albeit LOW MICRON design and not mass transfer!

So if you can give us a better description, maybe someone can give an answer.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2003

That's right GPC stands for Gold potassium cyanide. It's used in semiconductor company doing plating.

Kalaimani s/o Samyvelu
Plastics and pollution control system - Kuala Lumpur, FT. Malaysia
2003

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Yes, the gold plating tank can be exhausted and the fumes removed via a packed bed liquid scrubber. If you are implying a strict chemical interpretation to the term 'neutralized', as opposed to the more generic meaning of the toxic effects being neutralized, it should be possible to run a solution of alkalinized sodium hypochlorite as the scrubbing liquor.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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2003

Well, Ted mentioned a packed bed scrubber ... mainly because that's what, I assume, he had been used to in the past.

But I think your GPC is innocuous, fairly innocuous anyhow, and an ordinary l2 micron blade type horizontal flow eliminator should work well. Heck, I've got these in use from Papua, New Guinea to Alaska FOR ALL ASSAY FUME EMISSIONS, which, I hope you know, often consist of aqua regia, HCl (boiled off at ll0 °C) nitric, HF, HCl, sulfuric (boiled off at 320 °C) and, my favourite, Perchloric. Sometimes, particularly for the USA, I've gone to a 3 micron design, again inertial capture ... and some are over 22 years old and still working A.OK ... ask Placer Research in Vancouver! But they do need, like a so-called wet scrubber, to be constantly washed down. Compact, horizontal flow and often replacing mass transfer scrubbers.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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Thanks Ted/Freeman,

Actually I think the generic meaning of neutralization is more appropriate for this situation. What would be the chemicals required to neutralize the toxicity of Gold potassium cyanide that will not cause harm to environment if discharged. Will neutralizing it with alkalinized sodium hypochlorite cause the formation of new toxic chemical?

Kalaimani s/o Samyvelu
Plastics and pollution control system - Kuala Lumpur, FT. Malaysia
2003

What I meant in drawing the distinction is that a packed-bed fume-scrubber will remove the potassium gold cyanide in the exhaust, thus "neutralizing" the bad effects, without actually having to chemically neutralize the solution.

Alkaline chlorination will destroy the potassium gold cyanide (in theory), thus allowing discharge of the treated wastewater. Wastewater treatment is however a complicated issue and this is probably not even the direction you should be going in :-)

Most shops would pass any water that contains potassium gold cyanide through an ion exchanger to capture the gold value.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003