That's Linotype!
Very much sought after by people who hardcast smokeless. I've found it to be a bit too much for .45acp velocities, but 9mm it's about right without having to use a gas check.
With .45acp I use it to "sweeten the pot" a bit as it's tough for most people to get. (I know a printer and can get more than I can handle - need to go back with cash in hand).
You can cast balls from it. I wouldn't expect these to expand, and may be tough to load depending upon how thick you patch it. I use .490" and about .012" patch give or take. This combo works very well for me, makes for easy-enough loading, and gives me wiggle room for a .015" patch when I run across some material for that.
There are a group of experienced muzzleloading folks over on another forum who are experimenting with 60:1 to 40:1. Been doing that myself and it's very acceptable, especially with regards to accuracy.
IIRC, Linotype contains something like 85% lead, 10% tin and 5% antimony. May have the tin and antimony contents mixed around, but it's high and makes for awesome smokeless bullets.
If you don't want to cast this hard, trade it off for pure lead. Smokeless casters will thank you.
If it's not much you have, you might just keep it as a souvenir from a bygone era.
Josh