the crucial question is…what type of heat source are you melting
with? Fact is that all silver has to be at the same temperature in
order to be fully liquid. Are you quiet sure that you’re dealing with
only silver items.
It might be worth it trying to melt a lower quantity of metal to see
if your heat source can deal with it.
My first quess is that your heat source can’t keep up with the
amount of metal you’re trying to melt.
BTW, a reducing flame with enough energy (flame with a yellowisch
tip) is used for melting silver. Silver can absorb about 20 times
it’s volume in oxygen caussing copperoxydul. A redundancy of oxygene
is a no go for melting silver!
Let us know.
Enjoy and have fun