It can be done, but you need to figure out how to insulate the work so
you can get the work a little hotter.

You need to have every thing clean and use flux. With propane it will
take longer to get hot enough, this means more time for the work to
oxidize. To counter that you need more flux.

You are at the limit of doing it. If you have access to a ceramics
kiln, you might try that. If you have access to a welder, you might
try using a carbon arc to heat things.

Dan