Generally, the grading range is 25% ~ 35%, but the intermediate grading in practical application is mostly 28% ~ 32%. LM vertical roller mill steel ball grade ratio under common economic operation: steel ball diameter mm Φ one hundred Φ eighty Φ sixty Φ forty Φ 20 mass / total filling quantity 7.5% 6.9% 33.5% 30.1% 22 note: when the grindability of materials is...