Can treatment stop a heavy powder from settling?

It helps, but it cannot change the physics. Settling is a density and particle-size problem; treatment only changes surface compatibility.

What treatment does: better compatibility with the continuous phase means fewer agglomerates, and smaller effective particles settle more slowly. The layer can also add a little steric hindrance, which slows flocculation.

What it cannot do: if the powder is much denser than the phase — TiO2 in a light oil — the density difference is unchanged, and a long undisturbed shelf life will still produce sediment.

So the practical answer is a combination: a treated grade to slow it, a suspending agent such as an organically modified clay or fumed silica to give the system a yield value, and particle-size control to keep the coarse tail out.

Test with a centrifuge for a fast read, then sit a sample at ambient for one to three months and watch sediment height and how easily it redisperses. Redispersibility matters more than height: a visible sediment that shakes back in is fine, while a small hard cake is the worse outcome.