Sciencemadness Discussion Board

Recovering HCl from waste aqua regia

danieldavies - 18-10-2021 at 07:52

I have been dissolving copper in aqua regia and was wondering if there was a way to recover the HCl from the solution? I want to keep the nitric out of it.

itsallgoodjames - 18-10-2021 at 12:20

Why? I mean, there's ways to recover the chloride ions from solution, but unless it's some weird isotopically enriched chlorine or something, I don't see the point. Might as well just use new HCl, or if that's not available for you, react sodium chloride (If you're somewhere that gets ice on the roads in winter, you should be able to get salt meant for removing it for less than a dollar per kilogram) with an acid that is more available, and dissolve the resulting hydrogen chloride in water.

danieldavies - 18-10-2021 at 23:19

I recover and refine gold in my spare time. I am looking to get the most out of my chemicals before i discard them. Where i live, the acids ain't the cheapest. Thanks for your reply.

SHADYCHASE54 - 19-10-2021 at 08:01

I have to agree with itsallgoodjames, with a big fat why? I refine P.G.M's as well, for smithing purposes, and the cheapest acid for purchase is HCl. What part of the world is it so expensive? As I have found buying muriatic acid a gallon or 20 gallons at a time is reasonably cost effective however, you would have to be processing 0.2-2ozt Au per run to be storing such large amounts of acids. It doesn't sound to me like you are refining large amounts otherwise HCL wouldnt be where you would be trying to save money. Optimizing HCl waste might be worthwhile at the industrial scale, I don't know? I doubt it though in that HCl is dirt cheap the more you buy, also it's redally available at least in the Americas, both north and south.

If you want to go cheaper try for other methods like cyanide leaching, just kidding!
I mean it I'm kidding! Please don't do that, I make the joke only to highlight cheaper isn't always better.

danieldavies - 19-10-2021 at 09:02

I am in the uk. There is a lot of laws in place when it comes to buying chemicals. I was just looking to get the most out of my chemicals. Most of my material has a lot of copper, so i use a lot of acid for very little gold.

I have actually used cyanide leaching in the past, its just hard work to make.