After cementing with copper

[siddharta]

I cemented used AR leftovers with copper for the first time. I left copper plate in the solution for 4 days. Today I filtered the solution and in filter there was only whitish powder. The solution is still dark green. I put an iron bar into it to cement other metals.

When I rinsed copper plate with spray bottle some white-ish stuff started to peel off. I believe those are some salts? Silver maybe? And on the copper there is some brown powder. It was on the bottom of the vessel also. Could it be gold? The washing solution is blue green... And on the bottom there are some white sediments. Those I washed off the copper plate.

So what should I do now to successfully extract gold from sediments?

1. filter the solution
2. add boiling water and filter again?
3. add HCl and heat it up and filter again?
4. put the remainings into fresh AR batch?

I am not comfortable to use ammonia yet.

Here are some pics:

https://plus.google.com/u/0/photos/115858506204540699934/albums/5823388723510932097?tab=Xq

 

[Labman]

The whitish powder is copper monochloride. The golden brown is gold. Water spray the powder from the copper sheet. Since you don't want to use ammonia use concentrated muriatic acid to dissolve the white powder and collect the gold when it settles.

 

[siddharta]

Great. Thank you for help.

 

[butcher]

siddharta,

Since you had a lot of metals in the aqua regia solution with some possible gold, I will base my answer of most likely tin in solution also, the solution or what you have now may or may not contain gold, as gold could have plated out back onto undissolved metal this solution came from.

Wash powders in boiling water letting powders settle, but decanting hot, this will help to remove water soluble material like some copper, lead chloride, and sodium chlorides.

Put powders on low heat and dry, incinerate keeping powders crushed incinerate till powders are red hot, stir well to expose to air cool, ad boil in HCl take up liquid from settled powders with just a little added water, give the several more washes in boiling hot water giving powder time to settle but keeping washes hot when decanting, this will help to remove tin, lead and copper chlorides, note silver chloride is fluffy white and will not be soluble here but in will have to be given time to settle, also if solutions are highly colored give them another treatment in is showing you still have metals the solution will dissolve.

This should leave you with impure gold and silver chloride to deal with.

At this point I would save these in a jar covered with water and get back to reading my Hokes book, and reading dealing with waste in the safety section to be sure I understood how to deal with what other waste I had properly.

 

[Geo]

siddharta, as you are a beginner, i wont go into all the things that i think you could have done differently. i will say that you have put your self and the rest of us at a disadvantage by not starting your post like this, "i tested the solution with stannous chloride it was positive for gold". since this is spent solution, its highly unlikely that there is any gold there. you have ask a question (what should i do) when you did not give enough information to make an informed decision.

i would say to let all the solids settle and decant all the spent solution. dry and incinerate the powders. do a hard boil in hcl followed by a couple of water rinses until the water stays clear. any solids left at this point will be something good (or should be).redissolve and test with stannous chloride to find out what you have in solution.

 

[siddharta]

Geo and Butcher thank you for replying.

I will have to read Hokes again obviously. When I studied this forum and the book everything made sense to me but when dealing with actual stuff is far different. So many things that suprises me.

Geo, this is not AR solution. This is only the water that I rinsed copper sheet with. And the values that were on the copper sheet.
But it is interesting... When I tested spent AR solution it was negative (no color change at all). But on copper there is some brown sludge. And stannous works ok, have been testing AUCl from foils with it few days ago.

I was thinking to HCl boil and water rinses as you and Butcher sugested and then trow in with next AR what will be left from this...
Btw, this is from CPU batch that we talked about via PM's.

Boris.

 

[Geo]

i wouldnt put the powders in my next batch. it would be at the least another contaminant to deal with trying to get the gold. there will be more of the same from the next batch if you work it like the last one. i would wait until i had enough to to process separately. if it cemented from spent AR after SMB it could be any of the noble metals but i would put my money on Palladium. thats how i have been collecting the suspect powder i have. i treat all my left over and spent solution with copper. its never much, but it all adds up.