Weird AR Color????

[dmarth10]

I had a batch of converters in the AR and boiled it was just getting darker and darker. I was reading a lazersteve reply and he said add zinc to precipitate. The color should be clear with a gray suspension in it. I added zinc and there were no color changes. I dont know whats wrong. I kept adding zinc. There was absolutely no color change. Oh yea, I forgot to add that it was vacuum filtered 2 times. Second time there were no particles cought in the filter. Is something wrong that the solution is black and wont change color? His reply was in catalytic converter recover and refine in the help needed section.

 

[lazersteve]

The color of the pregnant AR will vary depending on the type(s) of converters, number processed, and duration of the AR treatment.

A minimum treatment time would be 2-4 hours.

The final color can vary from light yellow, red, brown, orange, or dark green.

Once the AR extraction is completed filter out the solids and Denox the pregnant AR solution. The final solution should be 100% free of particulate and sediment.

Neutralize the AR to a pH 3-5 with soda ash.

Treat the solution with zinc until the color of the solution changes to gray black and remains that color. The gray-black powder will settle to the bottom in 15-30 minutes. The solution should be a very clear with a slight tint of green or light yellow when the PGMs are all precipitated. Test with Stannous to confirm the PGMs are all removed. Hoke states approximately 1 pound of zinc per 3 gallons of solution as a baseline reference.

Filter out the mixed gray powder and then rinse the PGM powder into a small beaker.

Wash the PGM powder with HCl and rinse several times with water.

Separate and precipitate the PGMS as normal.

Steve