On 28 Oct, 13:01, The Natural Philosopher
wrote:
Coke was initially developed to cast iron making - cf Abraham Darby and
the BLAST furnace.

And your point is?

By Trevithick's day, coke had a hundred years of use in ironfounding.
It was easily available to the early locomotive builders, and they
chose to use it.


BTW - It wasn't developed for cast iron making either, but for use in
the blast furnace, the smelter for converting iron ore to pig iron.
This iron was later re-heated and manufactured as wrought iron
(hammered whilst hot and pasty rather than melted and poured). Cast
iron came a little later, as it required a less viscous melt if it was
to be pourable into moulds.