Re: huge precipitation from cat

[steeranoff]

Hi, today I did 1 lb. of honda honeycomb using lasersteve's dvd verbatim except I used poor man's ar. When I precipitated I got 6 coffee filters full of black precipitate. is that normal? what came out with the pgm's? how do I fix it?
please help
thanks,
steve

 

[lazersteve]

Steve,

If your solution was indeed 100% transparent (properly filtered using fine filter technique) before you added the zinc, then you have a mixture of Rh, Pt, Pd, and Cab-O-Sil (SiO2) from your zinc powder. If you used solid zinc turnings you should not see any SO2.

The black powder should be redissolved in true AR, as per the video, and the individual PGMs precipitated separately.

Edit:

If you used too much zinc powder you will have excessive black powder as well. Diluted HCl will dissolve the excess zinc powder, but it may also extract some of your Pd so be sure to test the wash solution with stannous as per the video.

Steve

 

[steeranoff]

lasersteve, I didn't filter the white precipitate off before adding the zinc. the acid was red and totally seethrough before adding soda ash. There also was no visible contamination in the red acid. Is it possible to yield the amounts that I'm talking about?

 

[lazersteve]

Steve,

Never judge your yields until you have melted the buttons.

You do not filter between the soda ash and zinc additions.

The mixed black powder can be contaminated with Cab-O-Sil, excess Zinc, and wash solutions. These will all make the yield appear larger than it actually is.

Your barren solution should be a very light green color.

Complete the processes as described on the DVD then determine your yields after the PGMs are separated and melted.

My best yielding cats produced 3+ grams of material per honeycomb.

Steve

 

[steeranoff]

Hi Steve. I sent a thank you earlier today on my phone. guess it didn't go through. I want you to know that I could not have done this without you. thanks,
steve