We don't have synonyms for caking coal yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are coking coal.
(n) :
(obsolete) A bituminous coal which softens and becomes pasty or semiviscid when heated. On increasing the heat, the volatile products are driven off, and a coherent, grayish-black, cellular mass of coke is left.
(n) :
(obsolete) A bituminous coal which softens and becomes pasty or semiviscid when heated. On increasing the heat, the volatile products are driven off, and a coherent, grayish-black, cellular mass of coke is left.