No coal is graded according to its energy content (CV) as well as its size. An A grade coal has a CV higher than 27,5 MJ/kg, a B grade between 26,5 -27,5 MJ/kg, a C grade between 25,5 – 26,5 MJ/kg etc.
A common misconception occurs when people discuss “export quality coal”.
Richards Bay Coal Terminal typically exports 2 different grades measured at 6500 kcal/kg and 5500 kcal/kg. This equates to 27.21 MJ/kg (a B grade) and 23,03 MJ/kg (an F grade). To convert kcal/jg to MJ/kg multiply by 0.004187.