problem with Aqua regia

[bkb000]

Hello all, first time to this forum, I've searched the topics and couldn't find my problem. I placed gold plated cutlery in a tub of hydrochloric acid and nitric, I added the hydrochloric first and immediate reaction and bubbling took place, then I added the nitric at a ratio of 1:3 and the reaction took off, after it settled I was left with a brown sludge.
Any ideas on what can be done would be much appreciated.

 

[Geo]

You made a mess. The reaction with the HCl tells me that the base metal was most likely zinc or pewter. You could have used just HCl and recovered the gold flakes (if it was gold) after the zinc dissolved. When you added the nitric acid, The gold tried to dissolve but was continuously being cemented back out of solution by the zinc. It continued this way, dissolving gold and cementing it back out, until the nitric was depleted and then the HCl dissolved the zinc until it was depleted. The mud is most likely a mixture of zinc chloride and undissolved zinc metal and if there was gold there, cemented gold powder. I'm not great with zinc chloride, someone else will have to help you straighten that one out.

Before you start back dissolving stuff, why not download a free copy of C.M. Hoke's book "refining precious metal waste". the link can be found in many of our members signature line. You may want to check out the forums guided tour here http://goldrefiningforum.com/phpBB3/viewtopic.php?p=6873#6873

Good luck.

 

[bkb000]

I certainly have made a mess, I'll check the download you suggested, thank you very much for replying, hopefully I don't need to dispose of it, as it was a substantial amount of cutlery with thick 24k plating, now I've got cutlery with no plating and brown liquid sludge.

 

[bkb000]

 

[nickvc]

You may have been lucky here, was the cutlery stainless steel?
If so you may have removed the gold plating but not fully dissolved the gold.
If your cutlery has brown stains it may well still have cemented gold on it.
My advice is to rinse off any acid from the cutlery and keep the liquid and sludge together in a sealed container somewhere safe, keep the cutlery again covered and do some studying and reading here on the forum before continuing your recovery and refining.
Your gold is safe so long as you don't throw it away so do the right thing and read.