Wait, how does that make sense?

What kind of energy if not electrical is coal being used to produce?

I think the Wikipedia image (at the top of the page [1]) is simply wrong. If you follow the link to the source, [2, page 43], you get 396.3/2280.6 = 17.4% for coal in the US, "Primary energy: Consumption by fuel."

[1] 1https://en.wikipedia.org/wiki/Energy_in_the_United_States

[2] https://www.bp.com/content/dam/bp/pdf/energy-economics/stati...

I looked at the citation, someone put the wrong numbers in the pie chart: https://en.wikipedia.org/w/index.php?title=Energy_in_the_Uni...

Blast furnaces, heating, other chemical processes.

Coal isn't used for heating much in the US, if at all. It is sometimes used for metal production, especially on the east coast, but oddly, not on the west, where hydro is used.