Crusher hydraulic sys. failed & oil dripped onto the hot material & ignited. EE put out fire w/ fire extg. Fire would rekindle. Occurred several times, EE call fire dept, knocked heat out so oil not ignite again. Single fire did not burn for longer then 30 min. Report being filed becuase MSHA believes was a reportable fire. 7000-1 is not an admission that a reportable fire occurred