[astrodust]

Loading the cargo into close-packed hexagonal storage silos would prevent it from shifting too much during transport, and even if it did liquify, it wouldn't slide too far out of balance.

You can fill/empty these of granular cargo using large diameter hoses.

You could also create one or two special storage bins that can be rotated to an arbitrary degree to help right the ship if it gets into trouble. They're carrying ridiculous amounts of ballast, why not put some of it to use as a counter-weight?

[totalZero]

You dont need silos, just baffles. If the cargo doesn't slosh over to one side or another, then it cant solidify in such a position either.

[logfromblammo]

Lower a vertical baffle grid into the hold with a crane. Secure it to the hull. Fill the hold with bulk cargo. Ship it. Raise the baffle grid with a crane. Unload the bulk cargo. Repeat from start.

You just need open tops and open bottoms in the grid. Open at the top so the cargo can fill the cells between baffles, and open at the bottom so the grid can be raised out of the cargo.

[astrodust]

You'd probably have to vibrate the cargo and/or the baffle to get it to settle in, which could be tricky, but it's not impossible. Not a bad approach.

[mcguire]

The hatch would need to be the same size as the hold, as well.

[logfromblammo]

The baffle grid would need to be the same size as the deck opening. Those are rather large on bulkers, AFAIK. Permanent baffles with open sides can be installed in the sides of the holds. I think those parts probably have sloped sides to follow the bowl shaped cross-section of the ship anyway.

[tomatotomato37]

Because that's more expensive to implement/load/unload then dumping the whole heap in an open bay and insuring the hell out of it