Over heated silver

What I like about this craft is just when you think that you have one
part mastered something happens to humble you. In my case I needed
to find a way to recycle my silver scraps. My first problem was I
was using an acetylene torch which barley would get the silver hot
enough to be fluid but it would solidify at the mouth of the mold. I
used a whole “b” bottle of acetylene trying to get one ingot. This
led me to getting a oxy/acetylene torch which allowed many good pour.
Then came my idea to build my own mold so I could pore larger and
thinner sheets. I think there is too much surface exposed to the
ingot, or I’m not getting the mold hot enough. In trying to get a
good poor I must have got the silver to hot. After a while it got
very hard and even though I could melt small parts of the waste
silver it would solidify immediately. What has happened, and can it
be reversed?

Any ideas

Doug Darling
@DARLING