Hey Vietnow, welcome to the shard.
I had the same query when i first came here, in the end i didn't bother chasing it up because it didn't impact hugely on my miner. But i know exactly what you mean, it is a pain in the ass to smelt three different types (And when you have 1 of the smallest ore you can't do anything with it...)
But as far as i see it, if its either this ore, or no extra ore. I'll go with this