Involved in coproporphyrin-dependent heme b biosynthesis (PubMed:31794133). Catalyzes the insertion of ferrous iron into coproporphyrin III to form Fe-coproporphyrin III (PubMed:31794133). Fe-coproporphyrin III + 2 H(+) = coproporphyrin III + Fe(2+) kcat is 7.9 min(-1). Porphyrin-containing compound metabolism; protoheme biosynthesis. Monomer. Belongs to the ferrochelatase family.