Northland Fuels and Energy is the retailer in Healy from Usibelli Coal Mine.
Usibelli sizes thier coal to about 8" minus, and then sells it to Northland Fuels and Energy
Northland Coal has a two deck screen,
Product from top screen is about 8" down to about 1 5/8", good for hand fed.
Below the top deck and above the bottom deck they get Chestnut coal 1 5/8" to 11/16" Thank you Coal Berner for the size link, works good in my auger.
From the bottom deck 11/16" down to dust with alot of dust, and in the rain, the dust is coal mud, this becomes basically "Waste".
The outside diameter of my auger pipe is about 3.5" this is called 3" pipe in the trade, trade sizes are based on the original inside diameter of pipe.
So my auger pipe inside diameter is just over 3", 3.086" actual.
When operating it sounds like a small rock crusher, poping and crunching along.
Years ago my father was told we would need a 4" trade size pipe auger to feed Usibelli coal, that would have about a 4" inside diameter, this delayed our conversion to coal for ten years.
I have fed about 35 tons of coal and never broke a shear pin.
Usibelli coal is soft, it is actually Sub-Bituminous grade C.
Soft is a relative term, some Usibelli coal can be driven over with your pick up and only break some crumbs from the piece, other pieces would become dust.
This time of year Northland fuels probably only comes to Healy to load trucks once per month, in the winter they come Friday and Saturday each week.
You can come up to Healy and drive to the Northland Fuel Plant and walk the piles, Raw form Usibelli, Hand fed, Chestnut, "Waste".
The "Waste" is reportedly hauled to the local power plant and burned.