Dry grinding system and dry grinding method

A dry grinding method comprising:

• a grinding step of dry-grinding a material to be ground;
• a first classification step of classifying a ground product obtained through the grinding step, into fine powder having a relatively small average particle size and coarse powder having a relatively large average particle size;
• a second classification step of further classifying the coarse powder obtained through the first classification step, into fine powder having a relatively small average particle size and coarse powder having a relatively large average particle size;
• a returning step of returning to the grinding step the coarse powder obtained through the second classification step;
• a third classification step of further classifying the fine powder obtained through the second classification step, into fine powder having a relatively small average particle size and coarse powder having a relatively large average particle size;
• and
• a returning step of returning to the grinding step the coarse powder obtained through the third classification step;
• wherein the third classification step includes:
• a classification step of further classifying the resultant fine powder into ultrafine powder having a relatively small average particle size and fine powder having a relatively large average particle size;
• and
• a returning step of returning to the grinding step the ultrafine powder obtained through this classification step.