Similarly to the disc driver case, there does not appear to be much cohesive information published on the topic of coal and coal quality as it pertains to American railroads.
Drury included a short section on steam locomotive fuel, including a summary comment to the effect that railroads generally burned what was nearby. On that basis, and within reason, one might deduce that it was more a case of fitting locomotives to the available fuel than choosing an optimum fuel for a given locomotive.
Drury did though mention that the CNJ coal dock at Jersey City apparently had separate bins and chutes for bituminous coal, for the B&O, and anthracite for its own and Reading locomotives.
In respect of locomotive coal heating values, one can find some information here and there.
Already noted is that late UP steam locomotives were predicated on the use of soft (bituminous) coal of 11 800 BTU/lb.
The SP Lima-built 2-8-8-4s that operated between El Paso and Tucumcari were designed “to burn a low grade bituminous coal from the Dawson field in New Mexico.” It had a heating value of approximately 12 000 BTU/lb.
On the other hand the DM&IR Baldwin-built 2-8-8-4s were designed to burn “high-quality” eastern coal with a heating value of 13 500 BTU/lb. I understand that during the closed season, some of these locomotives operated on both the D&RGW and the NP. Presumably they burned whatever coal those roads were using at the time, although in the NP case, probably not the Rosebud lignite/sub-bituminous.
One source quoted the NP Rosebud coal as having a heating value of 9000 BTU/lb. Another did not quote numbers, but stated that it had half the heating value of high quality eastern coal and 65% of the heating value of NP’s Red Lodge coal. These two statements do not reconcile easily. If we take eastern coal at 13 500 BTU/lb, that gives a 6750 BTU/lb number for Rosebud, and roundly 10 400 BTU/lb for Red Lodge, the last number looking to be on the low side for western soft coal.
Some numbers from the U.K. from an authoritative source are 14 050 BTU/lb for Welsh coal and 12 560 BTU/lb for Yorkshire coal. The Welsh variety was generally regarded as being excellent steam coal.
And an oddity; apparently the Reading T-1 4-8-4 was designed to burn a mixture of 10% anthracite and 90% bituminous coal. Perhaps that was the maximum proportion of anthracite that could be handled in a conventionally-sized firebox.
Cheers,