SureShot72 said:
Thank you So Much Again Harold! This was my first and very exciting! I think I may of used a bit to much borax. There is a small piece stuck on top and the bottom has a thin coat.
If you don't mind dealing with borax after the button has solidified, you can sprinkle a trace on top of the button AFTER it has melted. If you have an adequate heat source, you can superheat the gold slightly, so it stays molten long enough for the borax to melt. Alternately, you can allow the button to freeze, then sprinkle a trace on the surface while it's still red hot. That will generally clean the surface of traces of discoloration. It does precious little in the way of improving quality of the gold---but it does look a little nicer. You can remove borax from a button by boiling the button in dilute sulfuric. If you have a heavy deposit, you can tap it lightly, using a small spoon, fracturing the deposit. The wash will remove traces without altering the surface.
I started with a propane torch. I had to finish with Map gas cause I could not get it hot enough to melt.
One of the harsh realities you'll come to understand is that you are wasting time with ANY torch that does not use oxygen. Even if you can achieve the melting point required, the time it takes wastes a huge amount of fuel, and you're drastically limited as to the volume you can melt. If you go beyond gold and silver, you won't achieve your goal at all---so you'd be well served to consider adding oxygen to your melting system.
A small discoloration on the top. I hope it is just from the Map gas.
Nope! Not from fuel. That's an indication of a minor amount of impurity in the gold. Probably a trace of copper (oxide). You will come to understand that it's not easy achieving 9995, although certainly possible. When you get down to high purity, you must use extreme care and practice very good hygiene in processing. Even the torch tip should be cleaned before melting pure.
I am very happy anyway. I think I will hold on to this one for a while, and maybe re-refine as I get better at this.
You should be happy! We all start somewhere. My first button was terrible as compared to yours---but it was very encouraging to get that far. I kept reading Hoke and finally conceded that her instructions were good---that I should stop trying to re-invent the wheel and go with what is known to work.
I am now still steaming down the rest of the liquid from this batch that would not drop. Do I need to add anything before SMB to help it precipitate?
The only reasons I can think of that would have prevented precipitation were to have used too little SMB, or that you had not eliminated all the free nitric. Evaporating isn't likely to achieve anything beneficial unless you evaporate to near dryness, then add HCl. That will help expel nitric.
Here's something I'd like you to try. Put your new gold button in with the solution you're evaporating, and add a little HCl. If you have an abundance of nitric present, it will be consumed by digesting some of the button. That's the way I dealt with nitric in all cases, for it was my choice to use slightly more than was required in many instances, to ensure that I had dissolved all of the values. That's particularly important when processing filings and polishing wastes.
The only thing you should do to a solution you are preparing to precipitate is to filter before precipitation. Beyond that, there's nothing required.
Harold
