Coal kev lag luam peb theem ruaj khov hlau nplaum synchronous lub cev muaj zog ncaj tsav siv conveyor

Cov khoom no yog cov cuab yeej txhawb nqa rau lub thee mine siv conveyor thiab tau xa mus rau cov neeg siv khoom siv, nrog cov lus pom zoo ntawm qhov chaw.