chlorine

[Moo]

Hi
as far as I know if you auric chloride soultion has been sitting for 24 hours u can heat it a little to remove excess chlorine. can this be done immediatly after filtering to speed things up?

 

[Palladium]

Yes. But let it cool after that.

 

[Moo]

Ok Palladium thanks mate

 

[tek4g63]

You may already know this, but I would like to share a recent experience I had that shows you exactly why cooling your auric chloride is important before precipitating.

3 days ago I dissolved some foils in HCL/CL, I let the solution sit out in my metal shed uncovered in front of a box fan that was blowing out the window ( drawing fumes through it and out the window ). It sat out there in this 100+ degree weather for over 24 hours.

This is my normal practice for HCL/CL, but it is normally not over 100 degrees. I filtered, added water, then SMB per the usual routine. The solution went clear, then brown cloudy, and then stayed brown cloudy for a very long time, very long. Usually the gold settles for me in about 2 hours tops and I can decant. This time it took over 24 hours! Then when I would try and decant the super fine powder would stir up and take forever to settle again. I just finally got to do my first hot water wash and it is still settling very slowly. I know it had to do with the heat because I made a second auric chloride and this time I used ice to dilute it after filtering and it acted normally.

My point is, follow the advice given and let your solution cool, or force it to cool before you precipitate our else you will be puling your hair out!

I'm not going any further with the wash cycles on the troublesome powder, I'm just going to dissolve in HCL/CL again, but this time chill the solution before dropping the gold. It will be much easier to wash after that.

 

[Moo]

Thankyou tek yes I had much a similiar experience as you beforehand not allowing my soulution to cool properly and im starting to run out of hair :mrgreen:

 

[Harold_V]

I routinely iced my solution prior to precipitation. It does no harm, and is a requirement if you have a highly concentrated solution, as mine were (up to five ounces/liter).

One major difference, however, is that I used SO2 gas for precipitation, not SMB.

Harold

 

[tek4g63]

I routinely iced my solution prior to precipitation. It does no harm, and is a requirement if you have a highly concentrated solution, as mine were (up to five ounces/liter).

One major difference, however, is that I used SO2 gas for precipitation, not SMB.

Harold

I have read that the reaction builds much more heat using SO2 gas.

Out of curiosity after positing my comment above I wanted to try something. I dissolved some SMB in water per the usual way I do it, but this time I poured it into an ice cube tray and made a couple SMB ice cubes. I had some auric chloride ready for precipitation. ( no where near the concentration you spoke of Harold.) I dropped in one of the cubes and what happened was pretty cool looking. The solution around the cube went clear, then a brown cloud formed just around the cube at first. You could see the gold rain down through the still yellow solution below the ice cube. Wasn't long before all the solution was brown like usual, but that first reaction was pretty cool.

 

[Palladium]

One of my favorite things is when you sprinkle dry smb on top and it forms little gold looking snow flakes, or when the whole top of the solution in the beaker turns like a gold oil slick.

 

[Moo]

some kool tips there
I ended up getting my gold from the solution but stannous is now giving a slight positive for platinum, worth worrying about?

 

[Geo]

evaporate it down and put it in your stock pot.