Why is it blue green? Pgm recovery from cat converter/mlccs.

[adam mizer]

I used zinc powder, works great. Second choice is thin zinc metal, but powder reacts like "now".
Got used to this zinc and how it reacts many years ago.
EDIT: You have to use it in additions as the reaction can be too much and foam over. It still took time and stirring but works well.
Copper is slow to dissolve. But I am thinking it will work. Slow.
EDIT: It is HCL Bleach. Don't know reaction of copper. But HCL needs bubbling air like AP solution.
The chlorine made from the bleach gets used up thats why you have to keep adding it. Also when heated even by the sun drives out the chlorine from the liquid.

 

[Yggdrasil]

Now would I be able to use copper instead of zinc powder to drop the pgms? Or would it be best to just stick to zinc

Zinc will drop most all metals while Copper will only drop precious metals and Mercury.
In this setting the Zinc will drop the ,metals from the Catalyst matrix as well.

 

[Zemalo]

Zinc will drop most all metals while Copper will only drop precious metals and Mercury.
In this setting the Zinc will drop the ,metals from the Catalyst matrix as well.

So in this case it would be more wise for me to use copper powder

 

[Yggdrasil]

So in this case it would be more wise for me to use copper powder

Yes.
Unless you are doing Cyanide leaching it is almost always better to use Copper powder. KEEP AWAY FROM ACIDS if Cyanide.
There is one drawback on Copper though and that is that proper stirring is vital so the PGMs don't plate out (passify) the Copper.
The use of fine powder will be beneficial, but still needs hard stirring.
With Zinc that is not that critical.
If you have a HCl based leach Aluminum may also be used.
Here it is important to not use too much and let it sit in the HCl as it sometimes gels up and becomes hard to filter.