Per the bold print (above quote) - because they make two different types of MLCCs
PM/MLCCs - the PM stands for Precious Metal/MLCCs --- the precious metals used in making this type MLCCs is silver & palladium
BM/MLCCs - the BM stands for Base Metal/MLCCs --- the base metals used in making this type MLCCs is copper & nickel
Dissolved copper = a blue solution
Dissolved nickel = a green solution
Dissolved copper/nickel = blue/green solution
So the MLCCs that you tried to leach were NOT PM/MLCCs but instead were BM/MLCCs
And for what it is worth leaching MLCCs is just about the worst way you can go about processing MLCCs
I have posted much about processing MLCCs which you can read about here ---------
https://goldrefiningforum.com/search/104938/?q=MLCCs&c[users]=kurtak&o=relevance
But - if you do leach MLCCs (the PM ones) HCl/bleach is the WRONG way to do it
That is because the HCl turns the silver in them to silver chloride which then gets lost in the ceramic mud (talked about in things I posted in above link)
Therefore IF (the VERY BIG IF) you are going to leach MLCCs (which as I say is NOT the best way to process) they NEED to be done with a nitric leaching & NOT a HCl leaching
The same is true with leaching CATs - it is just about the worst way to go about trying to recover the PMs from them & that is because you will only get "about" 70 - 80 % of the palladium --- "about" (plus/minus) 50 % of the platinum --- & VERY LITTLE of the rhodium
You can read more about that here ------------
https://goldrefiningforum.com/threads/large-volume-vs-small-volume-cat-processing.20573/
Bottom line - if you want to recover all of the PMs out of ceramics (MLCCs &/or CATs) you are far better served to smelt them
Can you recover PMs from ceramics with leaching ?
Yes --- BUT - you just can not & will not get all the PMs by way of leaching
Kurt