lazersteve said:
Ammonium Chloride will drop Pt as an orange powder.
Ammonium Chloride followed by Sodium Chlorate will drop Pd as a red powder.
Steve
Please pay attention to this:
The platinum group rarely precipitates from dilute solutions by that procedure, and won't always precipitate completely from a concentrated one. You can recover those trace values by following instructions, below.
Steve. I know you bought a copy of Hoke's book. In it, she talks about a stock pot. It's nothing more than a container in which you dump solutions that contain traces of values. To keep expenses down, you can use scrap steel (angle iron, etc.). It precipitates everything, but it's the easiest way to recover these values. Just keep adding solutions to the pot, decanting the solution after everything has precipitated. You'll know by the absence of color in the solution. Decant it and allow it to settle a second time, saving anything that settles out. You can expect the values to look similar to that which comes from your stripping cell---black, and eager to rust when it dries. When you have enough of the crud to filter, do so, then dry it and store it, filter paper and all. You'll incinerate the entire lot before attempting recovery at some time in the future. You can do that chemically, or by furnace reduction. The whole idea here is to concentrate the traces until you have enough to recover successfully. I've done it countless times in my years.
Steel in your stock pot is consumed slowly, so you must add occasionally. You can also use scrap aluminum, but it reacts quite rapidly and can be the source of considerable gas and heated solutions. Steel was always my choice. Don't throw away anything that comes out of the stock pot, regardless of how useless it may appear. If it isn't consumed by the chemicals, it should be incinerated along with the values you've saved. You'll notice that they stick to everything, which is the reason to recycle what ever comes out of the pot.
If, by chance, your solution is extremely high in copper and you prefer to not precipitate it with the values, you can recover them by using copper instead of steel or aluminum. Again, you'll be looking for a black precipitate, but it will be sparse, as you might imagine.
Harold
