Grinding operations, the mineral material to the mill after a grinding run out, known as open grinding. Crushing equipment Since the Ore Milling Equipment itself has no ability to control the particle size, so the grinder in the mine both qualified grain, but also unqualified coarse or even coarse. Therefore, the ball mill is not suitable for open grinding. The rod mill is different, and the coarse pieces present between the rods will be preferentially broken, and the upward movement of the rods is like a number of grid sieves. , Bar mill with a certain ability to control the size, so the grinding machine can open grinding. Closed-circuit grinding: As the ball mill itself does not control the granularity of the ability, crushing equipment circular vibrating screen only by the mill outside the grading machine to control the particle size, mill ore drain into the grading machine. Qualified fine-grained removal of the grinding grading cycle, unqualified coarse or coarse pieces returned to the mill again grinding, known as closed-circuit grinding. Therefore, closed-circuit grinding unqualified coarse particles not only through the mill once, must always be ground until the qualified group was discharged. Almost all of the grinding machine must be closed-circuit grinding, rod mill can open grinding, can also be closed-circuit grinding. Open grinding and closed-circuit grinding comparison: The work of the mill is divided into open and closed two. The closed-circuit work, but also divided into closed and semi-closed (or partial closed circuit). Open grinding, at this time by the grinding material only through the mill once. Fully closed grinding. At this time the mill is discharged by the grading machine is divided into fine Xinjiang and coarse to the sand, broken equipment back to the sand all the Ore Milling Equipment and then grinding. Grading machine back to the sand only part of the original mill to re-grinding, the other part of the next paragraph to the mill, it is a partial closed circuit. There are three types of grading machines in the grinding cycle. Jaw crusher is a pre-grading role; grading machine in the grading machine 1 and open-circuit grinding grading machine 1 and 2, are check grading; closed-circuit grinding grading machine, both pre-grading, and check The role of grading. The classifier 2 plays a role in the classification of the flow control, which reclassifies the feed streamer of the classifier 1, separates the chargers therein, and breaks the equipment to obtain finer and more finished products.