Any input welcome on how to recover AuCl after spillage

Wiehan

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I have spilt gold chloride onto a concrete floor and would welcome any inputs on how to go about recovering it. My thoughts are to break up the concrete, pulverize it into a fine powder form and then run it through aqua regia. Any other thoughts or ideas will be appreciated
 

nickvc

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Welcome to the forum.
This really depends on how much gold you think you lost and is it worth the effort to recover it and the cost of replacing your surface.
If you do think it’s worth it why use AR when HCl is sold as cement cleaner , it should dissolve the cement and allow you to filter the remaining solution to recover your gold.
 

4metals

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I am not of a mind that you will recover the values from pulverized concrete. As Nick mentions it depends on the quantity of gold you lost.

True story, I had a client about 10 years back who set up an acid refining setup for aqua regia work. In the design I included a berm in the room to contain spills and the floor was to be coated with a Novolac epoxy resin to resist attack from the acids and essentially seal the porous concrete. They built a beautiful berm but never coated the concrete. All was fine for a year or so until a loaded 72 liter flask with a working volume of 40 liters broke and spilled on the concrete. The vessel was loaded with acid from a large 14 karat digestion. The concrete did a wonderful job of sopping up the spill and a spot about 6 feet in diameter clearly defined where the acid had been absorbed. They were freaking out because the were looking for about 175 ounces of fine gold from the lot or north of a quarter of a million dollars. The concrete was chipped out and it was easy to see where the values were contained by the color of the concrete. When the entire crater of cement was cleared, it was crushed and made into prepared sweeps. They constantly shipped prepared sweeps anyway so the dust was sampled and shipped. It wasn't an easy assay because the flux had to be adjusted to accommodate the concrete but eventually we got a fusion without any lingering beads and got a reproducible assay. End result was they were paid for all of the expected gold less the fees for processing sweeps, which are higher than processing karat.

So if there is enough gold to justify it, crush and sift it and ship it as a powder. Based solely on the issues with the assay of the crushed concrete I encountered with the clients spill, I think an acid digestion would be a problem.
 

Wiehan

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Hello guys,

Thank you for your inputs, highly appreciated! We've lost 75 ounces in the incident and managed to recover about 10 ounces immediately. Although I do not foresee a full recovery, I do deem it worth the effort to at least give it a good try.

@nickvc - your comment about HCL noted. Thanks for that.

@4metals - the floor in the area where the incident happened is mostly ceramic tiles. Unfortunately, the spot where the spillage occurred was on a bare piece of concrete. About a month ago we initiated discussions to redo the entire area floor with exactly what you've mentioned, Novolac epoxy. So I also thank you for confirming this as a good choice. Unfortunately though, we haven't had that done before the incident, but now gives so much more reason why it should be done. Also in contemplation is the design of berms in critical areas, so it is comforting to know that we are on the right track after reading your comment.
 

nickvc

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I wish you luck in the recovery as that’s a big hit in your pocket.
In the one refinery I worked in we had channels in the floor running to a below floor level catch tank so we could wash any spills into the tank for later recovery, much easier than trying to mop up any spills, simply spray the spills with water into the channels and then into the tank, dry the floor with paper towels and throw them into the sweeps.
 
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