A ball mill is a form of grinder that is used to blend or grind materials for use. It is a cylindrical device mainly for grinding material such as iron ores, ceramic raw materials, glass, steel, etc. The ball mill works on impact and attrition principle. Its impact is the size reduction given that the balls drop from almost the top of the shell. The balls are the grinding media which could be made of ceramic, rubber, steel, etc. ball mills operate by rotating around a horizontal axis almost filled with the material to be ground and the grinding media. The end result is the reduction of the material to a fine powder.
Ball mills are not only used for grinding, they can also be used for cold welding. One advantage of ball mill is that it is suitable for grinding materials of all degree and hardness because of its many options of grinding media. The grinding media options are discussed below:
Ceramic Grinding Media
This grinding media is made of ceramic as the name suggests. It is used occasionally in small-sized mills in the industries such as the chemical industry and food industry. Ceramic balls for ball mill could be in high or regular density. Regular ceramic balls are often porcelain balls and high-density ceramic balls are more abrasion resistant as they are made with high alumina oxide content.
Ceramic grinding media are well suited for procedures that involve mixing and dispersing because of its abrasion-resistant function. For example, in pharmaceutical processes, ceramic grinding media is used to prevent impurities.
Glass Grinding Media
Glass ball mills were developed mainly for grinding processes that do not involve sand particles. Glass ball mills are ideal for grinding of pigments in mills vertically and also horizontally. Glass ball mills are particularly suited for applications in mills because of their specific mass which can process low and medium viscosity mill bases. The glass beads, that is, the glass ball meals are thermally and chemically treated to maintain high polish and intense impact and wear resistance.
Steel Grinding Media
Steel grinding media is used in mining where they are used to extract precious metals in ore mineral processing. Since ore particles must go through the grinding process, steel grinding media are ideal for such a grinding process. Steel ball grinding media are made from alloys of iron and carbon. By increasing the carbon content to produce cast irons, both the hardness and wear resistance are improved significantly.
There are different types of steel ball mills, they are, cast nickel alloys, stainless steel. They are usually applied in the grinding process of copper, gold, iron ore and polymetallic. Steel ball grinding media are used in tower mills, Isa mill, rotary mills, semi-autogenous grinding (SAG) mill.
Plastic Grinding Media
Plastic ball mills are made from high quality and special resin. Plastic ball mills can be used as a substitute for metallic ball mill in low load bearings and they are cost effective. They can be used in various applications, they can serve as agitators in aerosol spray cans, medical diagnostics, etc.
