learned 4 yrs late - Page 2

Lead, is dried and then treated using pyrometallurgy. The concentrate is sintered before being smelted in to produce a 97% Lead concentrate. The Lead is then cooled in stages which causes the lighter impurites (dross) to rise to the surface where they can be removed. The molten Lead bullion is then refined by additional smelting with air being passed over the Lead to form a slag layer containing any remaining impurities and producing 99.9% pure Lead.
this site could be of some use keep on learning
Secondary Lead Production, Secondary Smelting, Secondary Lead Refining

As a time line -
post #18 was my third attempt #19 in part was me noticing a issue of third attempt . A Sponge lead rock with weight sinking into the molten mix & absorbing some of the lead , not good
but #20 was my second attempt and I was not sure why it went well compared to third try. .
So if I use my time line I will now -
Clean the plates of what common sense tells you will not melt .
then put in a AL pot .
Walk away for a few weeks let nature work . When you consider lead was used in plumbing applications
& during demo work never seems aged from life . I now see the longer the better if you were to let the plates just weather out .Some of the Oxides naturally fade away back to the eliminates of earth via natural Hydrolysis

https://en.wikipedia.org/wiki/Oxide
I feel letting soak with Sodium bicarbonate at one point most likely will help also
this https://en.wikipedia.org/wiki/Baking_soda


https://en.wikipedia.org/wiki/Oxide

https://en.wikipedia.org/wiki/Lead
after reading these Wiki references
You realize Lead does tarnish a bit but is very stable , will not rust away if left to the normal events of life

" has a half-life that is so long (much longer than the age of the universe) that it can be considered stable "

What is Half Life ? https://en.wikipedia.org/wiki/Half-life

I see why lead is essential to batteries now
it resists decay so well in nature - that forcing a bond with oxidizers and immersion in the acids, allows us to take advantage of leads natural resistance to not decay
This must facilitate storage of electricity