Ball drum mill. Design, structure diagram, operating principle, calculation basis
It is clear that an industrial mill is one of necessary components of a grinding and screening complex. Using the mills, different ore and non-ore mineral resources, average hardness construction materials, slags and production waste materials are ground.
The Samara Strommashina plant has been manufacturing different grinding equipment for 70 years. It is a widely known ball mill manufacturer with increased indices of production capacity and reliability. All ball mills for sale manufactured by the Strommashinacan be divided into several types. Depending on the mill design features and material grinding methods, mills are classified as drum mill, bowl mill, rod mill, hammer mill and tubular mill.
Let us consider the design of a drum ball mill – one of the most popular industrial equipment types.
The drum type ball mills are used for grinding hard-ground materials (in ceramic, tool-making and other industries). The mill is a cylindrical drum installed on bearings and driven by a motor through a gearbox.
The material is charged and discharged through a latch. Capacity of mills is determined by their volume (1 to 7 m3) and duration of grinding depending of the material type and grinding fineness. Specific charge of the mills is 0.35 to 0.45 t/m3 of the drum volume.
The continuous-action drum mills discharged through a meshy end diaphragm are used in silicate, ceramic and other industries. The material is charged into the mill by the feeder through an opening in the cover via which the material is fed into the mill drum. The latter is installed with journals integral with flanges, in bearings. The lower surface of the bearing housing is spherical, and it is supported by the block. Such a connection allows compensating inaccuracies of installation and other deformations of the mill housing. The mill drive is designed according to the diagram: motor – belt-and-pulley arrangement – unclosed gear set.
The finished product is discharged through the right hollow spigot. Small material particles pass through the slots in the end diaphragm the right-hand side of which is equipped with lifter blades. These blades lift and throw the material onto the conical hub and further through the spigot to the outlet. The use of the end diaphragm increases the mill capacity as the finished fractions are processed more intensively due to low position of the discharge zone. The internal surface of the drum is lined with armour plates made of wear-resistant steels.
Depending on the operation conditions and mill types, the following armour plate profiles are used: stepped, corrugated with bolted and boltless fastening, heel-type plates. The latter feature increased wear resistance but increased coherence with the material. The plate design shall ensure easy replacement of the armour plates. To decrease the noise, gaskets are installed between the housing and the plates.
The ball mill with peripheral discharge is used for grinding gypsum, clay, lime and other materials. The ground material passes through the holes in the plates fixed in the end walls and falls onto the sieve which passes less than 3 mm particles, while coarser particles are returned into the drum for remilling via gaps between the armour plates which are located stepwise in rotation direction. The mesh size shall be selected based on the grinding fineness. The particles which do not pass through it are returned for remilling. The finished product is collected in the bottom part of the housing. During open-cycle operation the material is ground to 0.5 mm. To produce a finer grinding, the mill shall operate in a closed-cycle mode with a separator.
The ball drum mills (BDM) are designed for grinding clay slates, anthracites, lignite and black coals. Such mill types are mostly used in thermal electric power plants as they are designed for continuous operation in dust production systems. The coal is ground by impact and abrasion action of the balls charged into the horizontally arranged and bearing-supported drum.
In ventilated drums the coal is ground simultaneously with its drying inside the drum. The coal with a drying agent are fed into the drum through a coal-feeding nozzle, and the coal dust is removed from the drum through the coal-feeding nozzle by the same agent. The size of a fuel piece fed for grinding shall not exceed 25 mm.
The Samara Strommashina plant is a supplier of a wide range of industrial mills, crushing and grinding equipment and other development which allow a new look at your enterprise's processes.
High-skilled personnel, research experience, modern technologies, cooperation with research and development institutes, a well-tuned industrial process allow manufacturing the competitive equipment demanded currently.
Based on the equipment we manufacture we are able to select a technology and configure the main and customised equipment for mineral and artificial raw material grinding process lines.