gone wrong somewhere

[geoffromoz]

Seasons greetings to all.

I stripped around a pound and a half of scrap jewellery in Nitric acid as per Hoke, filtered of the green solution leaving only a light brown sludge in my casserole dish then added more Nitric acid three times to burn of as much base metal as possible.
Removed Nitric acid solution down to brown sludge. (could I have rinsed, filtered and dried this sludge and had reasonably fine gold as stated in Hoke.) I continued on with Aqua Regia 1 to 3 mix Nitric to Hydrochloric. I then had a clear yellow solution after 2 day’s of settling with the residue of metals in the bottom of my casserole dish. I then syphoned of the gold bearing solution and filtered it. I spilt this into 2 equal parts not having a jar capable of holding it all. I diluted both containers with 3 parts water. Then I made my first mistake, I added SMB to one jar, there was no precipitation then I realised I had not neutralised the Nitric acid with urea first can this batch be saved!. I added urea to the second batch and as you can see from the pics. There seems to be something wrong. The floating pieces have the look of a disintegrating car washing sponge.
Have I added to much or to little urea I have no idea what I have done wrong.
Can anyone? help with powdered tin hard to find here. I have ‘Bernzomatic’ metal work solder the packet does not have it’s base make up on it I looked at there web site it’s not there either.
attachment=0]added urea.JPG[/attachment]

Geoffromoz

 

[lazersteve]

Are you using true nitric or the homemade stuff?

A stannous test would be very helpful.

Boiling down the AR solution prevents the need for Urea.

Steve

 

[geoffromoz]

Hi, Steve. I use chemistry grade nitric 70%. I'm having trouble getting powdered tin for the stannous test. Is there anything other metal or solder I can make it with. I tried my local hardware store and chemist no result I dont think tin cans are coated with tin these days or I could scrape some of. any ideas.
geoffromoz

 

[chemist]

You may be able to get tin from lead-free solder. I bought a roll of solder from a stained glass supply store and it is 95% tin and 5% something else (antimony, I think). So far, it seems to work for me.

 

[butcher]

do they have pewter beer mugs down under?

http://en.wikipedia.org/wiki/Pewter
http://en.wikipedia.org/wiki/Tin

 

[geoffromoz]

Thanks folks, I have poured the contents of the jar into the casserole dish and stirred it some more. The flakes look very cryistallin a little like snow flakes. I can get my hands on some pewter from were I work so I will give it a go.
geoffromoz

 

[geonorts]

i get a simmilar thing sometimes for me it is from too much urea I either add more water to dissolve it or I filter it out (the white stuff you mentioned) then i rinse the filter and it dissolves anyway, as for making stannus, lead free solder can be found at any hardware store, dissolve in hcl and filter

 

[goaldspektre]

Happened to me once as well.Too much urea crystallizes,i heated the neutralized acid lightly and the crystals dissolved.I found heating also brings down the gold faster when adding smb.Make stannous first though and test test test!!!

 

[Sodbuster]

I always made my stannous from the lead free fishing sinkers.
TK

 

[Palladium]

Welcome back sodbuster. Hadn't seen you in awhile. How's life been treating you ?

 

[Sodbuster]

Palladium:
Thanks, I try to read everything ever posted to the forum. Got alot of catching up to do. Had me an open hart surgery back in may of 09, set me back a little bit.
But that didn't keep me from my workbench. Been working on getting the base metals out of my 28 lb's of electrical points all last summer.
I'll have to get me some pictures of some of my silver buttons to show off.
I even got me my first little gold button (7.5g) can't wate to show off.
Could not have done it without the help of anybody and everybody who ever posted to the forum, it's all educational.
Thanks to everyone
Read Read and Read
TK

 

[aflacglobal]

Glad to see you back Sod.