Involved in coproporphyrin-dependent heme b biosynthesis (PubMed:25646457). Catalyzes the insertion of ferrous iron into coproporphyrin III to form Fe-coproporphyrin III (PubMed:25646457). Has weaker activity with coproporphyrin I, protoporphyrin IX, deuteroporphyrin, 2,4 hydroxyethyl and 2,4 disulfonate (PubMed:25646457, PubMed:11948160). Fe-coproporphyrin III + 2 H(+) = coproporphyrin III + Fe(2+) Binds 1 [2Fe-2S] cluster. kcat is 1.8 min(-1) with coproporphyrin III as substrate. kcat is 0.8 min(-1) with protoporphyrin IX as substrate. Porphyrin-containing compound metabolism; protoheme biosynthesis. Monomer. Was identified as a high-confidence drug target. Belongs to the ferrochelatase family.