The remaining coins from the pre mine are absolutely Safe, it cannot be sent to a burn address as there is currently no burn address Generator for hefty1.
Here is a burn address for hefty: SMJ12qn9jNCCXJnTYRz5Yu9ZenERpdErkh
basae58 decode, and you get this: 3f0000000000000000000000000000000000000000492d7df2
Elbandi