Ball Mill Grinding Media For Copper Mining . : 1) High Hardness: The surface hardness of forged and casting grinding media is to 6065 HRC and volume hardness is to 6063 HRC 2) High Impact Toughness: The impact toughness is more than 12 J/cm2; 3) Low Broken Rate: The actual broken rate is not higher than 1%; 4) Even Wearresistance ...