Grinding media for ball mills
Grinding media are necessary in many industries currently. Their main function is grinding, of course. They are used in different coal, lime and construction material production processes, in metallurgy for processing gold, uranium, copper, zinc, nickel, titanium ores, etc. In addition, grinding media are used to extract concentrates of various substances. A major role in manufacture of such comminutors is played by the production process itself and the quality of the raw material in use. For example, is steel balls are used as grinding media and compared with other types, then strength, durability and efficiency of steel items will be much higher than the those of balls made of any other materials.
There are two main grinding media types:
- steel and cast iron grinding balls and cylinders (cylpebs)
- high-aluminous (porcelain, corundum, uralite, albite) ceramic grinding balls and cylinders (cylpebs)
Steel and cast iron balls
Steel balls are used mostly as grinding media for coarse grinding in ball mills for mining, coal and other industries. The grinding balls are manufactured according to GOST 7524-89, their diameter is 22 to 125 mm.
Hardness group I, II balls are made of low-carbon steels.
Hardness group III, IV balls are made of high-quality steels with subsequent quenching.
One of the most high-demand and common types of grinding bodies today is porcelain balls. Such ceramic balls are acid-resistant (99.6%) and have very low water absorption level (0.01%), which makes them an excellent means used for filling different chemical, biotechnological and reaction vessels where they are used as a heat carrier and a reagent distributor. In addition, they can be used for ball mills to produce fine-ground material in pharmaceutical, chemical, mining and chemical and mining industries. The porcelain balls are a perfect choice for both liquid and colloidal, and for dry grinding types.
They are made of high-quality ceramics and contain aluminium oxide (Al2O3), silicon oxide (SiO2), iron oxide (Fe2O3), sodium oxide (Na2O), calcium oxide (CaO), potassium (K2O) and other substances. In addition, density of such balls is rather high and amounts 2.45 to 3.4 g/cm3, depending on the particular composition. The porcelain grinding media can be used in temperature range from 700 °C to 1200 °C, their actual mechanical compression strength is 150 to 1250 kgf/ball, and hourly abrasion capacity coefficient is no more than 1%, which is fairly good for ceramics.
Also we produce grinding media made of different silicates (oxide ceramics):
- aluminium oxide;
- zirconium oxide;
- zirconium silicate;
- titanium oxide;
- silicon nitride;
- silicon carbide.
When selecting a specific grinding medium type, one should take into consideration their important technical properties and influence of these properties on grinding process:
- specific gravity;
- chemical stability.