Hello bushman, welcome,
The problem with the large size bitum coal is that it is really large, usually softball size and larger... It's hard to shovel and work with... and I was feeding a big firebox, it held 120+# of coal. Maybe your coal source has different sizes??
If you are able to, sift the really fine pieces out of the coal... I used a fine-toothed pitchfork... Then I put the fines in paper grocery bags, rolled them up to make ~3" diameter 'logs' and added these to the fire on the sides, keeping the loose, larger pieces in the center...
You will have soot with bitum coal, unless you have a stove designed to burn off the soot,, and these are not common. You can try giving the fire a little above the fire air, instead of only below the fire air, but this only helps a little..
I'm not familiar with your stove, can you post some photos?