The ore is crushed and ground mining comes to feed particle size, particle size of ore to reduce the relative to the original, or even tens of thousands of, the whole process consists of crushing and grinding of two stages, roughly divided by 5mm particle size as the reference standard, crushing to crush, product size greater than 5mm, the grinding feed particle size below 5mm, crushing force to impact and grinding. Crushing and crushing, crushing and fine crushing; Vertical roller mill used in the grinding process and grinding is divided into coarse grinding and fine grinding.

In order to improve the grinding machine's working efficiency, and high power consumption and high material consumption of grinding to avoid "breaking" unnecessary work, try to use process of "more crushing and less grinding", reducing mill loss. The crusher is often associated with a joint working, vertical roller mill must work jointly with the classifier. Set the prescreening for crushing section, the materials can be without this broken material pre screening, can reduce the amount of ore into the crusher crushing and reduce unnecessary. And check the screening set in crushing the material can be not qualified grade returned to the crusher and crushing, check screening settings can strictly control the crushed product size.

Set the check screening not only increases the screen and return mine equipment, also increase the site and construction costs, so usually only in the size of the strict requirements of the fine work that uses. Crushed and broken usually only pre screening, if the coarse crusher and crusher production capacity is rich, can not set up the pre screening, because of pre screening equipment to increase equipment costs and loss of spatial height.

Particle size of ore milling than ore crushing stricter requirements, and the mill itself has no ability to control the particle size of the product (rod mill has a certain granularity control ability, can open circuit grinding), because the classifier, set to control the grinding in the mill must be outside, namely the closed-circuit grinding.