We have already described the primary processes of enrichment of minerals in mining and processing plants and equipment used in these processes. This article is about machines used in the process of grinding that called mills.
Types of grinding mills:
- Mechanical mills. Destruction of grains and particles of material comes in result of blows grinding media or their abrasive actions.
- Aerodynamic and pneumomechanical mills. The destruction of pieces is due to the acceleration of the air stream and the subsequent impacts on the fixed armor.
Mining and processing plants exclusively used mechanical mills as grinding machines. Mechanical mills classified by:
- Operating modes — continuous operation mills and batch operation mills;
- Grinding methods — wet grinding mills and dry grinding mills.
According to the principle of operation and construction mills divided into:
Drum mills classified into a rotating drum mills, vibratory mills and centrifugal mills. Mining and processing plants use rotating drum mills (pic. 1). Depending on the form of the grinding media there are ball mills, rod mills, pebble mills and autogenous grinding mills.
Grinding media — iron and steel balls with diameter of 15-120 mm, steel or cast iron cylpebs dimensions (diameter and length) of 16 to 25 and 30 and 40 mm, round steel bars with a diameter up to 130 mm and a length equal to the length of the drum.
The right choice of grinding media is very important. Researches with various forms of grinding media showed that grinding balls are superior in grinding efficiency. That’s why mining and processing plants use grinding balls as grinding media.