Jul 11, 2013 · GRADING OF COKING COAL Grades Ash content Steel I <15% Steel II 1518% Washery grade I 1821% Washery grade II 2124% Washery grade III 2428% Washery grade IV 2835% Semi coking I <19%(A+M) Semi coking II 1924%(A+M) Hard coke by product premium <25% Ordinary 2530% Beehive premium <27% Beehive superior 2731% Beehive .