Bead mill is a cylindrical vessel equipped with a stirrer or a stirring rotor having a number of support functions and providing different modes of mixing and circulation of beads. The mill is filled with beads at 70-80% capacity. When grinding, the chamber is filled with grinded powder suspension, which fills all the free space. Mill rotor operation makes beads move, thus grinding material particles. At the end of the operation the material suspension is drained from the mill. The industrial bead mill operates in continuous or circulation mode i.e. grinds pumped suspension. All modern mills can operate in this mode and have a sieve cartridge or a slot to separate beads from the suspension.

Bead mills are divided into two types - horizontal and vertical. The most popular type is the horizontal mill with a cylindrical chamber and a rotor arranged horizontally. Vertical mills are used primarily in the ceramics manufacture and grinding of durable materials. If the mill chamber is placed vertically, the bottom is experiencing high abrasive loading caused by weight of filled beads. This effect is useful in the processing of ceramic materials as it allows for a greater power density of grinding.

The bead mill rotor can have various configurations. Low energy input mills have rotors with eccentric elements, for example, rotors with 5-10 eccentric disks. To obtain a greater power density pin rotors having 4-6 circular pins and 4-10 lengthwise pins are used. The rotor may have a system for the circulation of the coolant and output of the material. Sensors and a product - beads separation system may also be embedded in the rotor. The outer part of the rotor is most loaded, the circumferential speed of the outer part is ~20 m/s. The rotation center is experiencing a minor load, a sieve cartridge can be placed there to output the product.

The bead mill chamber is a cylinder of 3-5 diameters length. The inner wall of the chamber is exposed to the greatest wear and typically has a removable lining. Chambers of industrial bead mills have a cooling jacket, which is used to maintain the desired temperature.

The end walls of the chamber have product input and output holes, a shaft sealing system and others.

The bead mill chamber can be steel or have a ceramic or polyurethane liner, depending on the task. Mill rotors are made of the same materials.

Beads are balls of 0.05-5 mm diameter. Beads are made of glass, zirconium silicate glass, zirconium silicate, zirconium oxide, aluminum oxide, porcelain, steel, stainless steel, tungsten carbide, silicon carbide, etc.

The mill operation causes a slight wear of all major structural components. Beads are added into the mill depending on the volume, other parts are replaced depending on the wear of working surfaces. The material is milled and comes out of the mill together with the product, which must be considered, for example, in the food and chemical industries. It is advisable to use steel balls to grind ferrites, aluminum oxide or zirconium silicate balls - for ceramics, and glass or ceramics - in the paint industry.

Proper selection of operating modes and materials plays a crucial role in the economic efficiency of the process and provides the desired purity of the product, if required by the technology. Bead mills operate in aqueous medium or in organic solvents. The suspension of material particles must be sufficiently flowable and resistant to precipitation in order to ensure stable operation.

The use of highly abrasion-resistant and highly hard ceramic beads allows to obtain an average particle size of less than 10 nm. The process of obtaining ultrafine powders by grinding is characterized by high energy costs. When performing submicron-scale grinding of crystals, the strength of grinded material reaches the theoretical limit due to the fracture of all agglomerates and defective crystals. As particles decrease the energy consumption grows quadratically, that is, the grinding rate decreases strongly, the amount of milled products and the share of secondary energy consumption increase, for example, for viscous friction. Nevertheless, modern technologies of bead milling allow to obtain nanoparticles. Units of the mill are made of zirconium dioxide, bead size is 50 microns. The highest abrasion resistance of the latter, the circulation system and cooling of the rotor and the body allow to obtain high specific energy parameters and low-contaminated samples. A distinctive feature of this technology is good reproducibility and process controllability.

To grind ore concentrates and other minerals a mill charged with graded sand or pebbles can be used prior to flotation. Reagents for the flotation process can be added before or after the mill. The same mill can be used to activate the ore and even for ore interaction with chemicals in the process of milling, for example, in gold recovery. In this process highly abrasion-resistant rounded natural materials are used as grinding bodies. Large particles of the ore concentrate can be used as grinding bodies. In this case a coarse fraction of ore is added into the mill from time to time, the feed is produced by a fine-fraction pulp.

The paint produced is supplied to steel plants, where it is directly applied to metal surfaces by means of a continuous dyeing of metal sheets. Coating is performed in several stages. A more detailed description of the entire coating process can be found below, but before that read some information on the types of coatings.