Nkà na ụzụ
A na-eme usoro carbon a na-arụ ọrụ site na coal kacha mma ahọpụtara nke ọma yana coal agwakọtara. Ịgwakọta ntụ ntụ coal na tar na mmiri, extrusion nke ihe agwakọta n'ime Columnar n'okpuru nrụgide mmanụ, na-esote carbonization, ịgbalite na oxidation.