jan 01, 2016 a primary gyratory crusher was required to crush iron ore at the rate of 3000 t/h. the largest size of the run-of-mine ore was 1000 mm. the required product size was less than 162 mm. manufacturers data indicated that the nearest size of gyratory crusher would be 1370 mm 1880 mm with a cone angle of 18.,gyratory crushers reduction,the gyratory crushers crush to reduce the size by a maximum of about one-tenth its size. usually, metallurgical operations require greater size reduction hence, the products from the primary crushers are conveyed to secondary or cone crushers where further reduction in size takes place. here, the maximum reduction ratio is about.