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A disc mill is a type of crusher that can be used to grind, cut, shear, shred, fiberize, pulverize, granulate, crack, rub, curl, fluff, twist, hull, blend, or refine. It works in a similar manner to the ancient Buhrstone mill in that the feedstock is fed between opposing discs or plates. The discs may be grooved, serrated, or spiked.
The first disc mill was invented by Kingsland in 1856. The mill consisted of a rotating disc positioned between two stationary discs. [1] [2] The grinding was adjusted by axial movement of the fixed discs. The mass with a concentration of 3-4% entered under pressure through an opening located in the center of one of the fixed discs, flowed through the grinding zone between the first pair of discs in the direction from the center to the periphery, squeezed into the subsequent 30HV of grinding formed by the second pair of discs, and, moving in the direction from the periphery to the center, flowed out through an opening located at the shaft. The rotating disc was 750 mm in diameter and operated at 250 rpm, hence at a circumferential velocity of about 10 m/sec. The grinding knives were made of bronze. With a power of 22-27 kW, the mill grinds 5-8 tons per day. с. fibers.
A more advanced grinding apparatus is the Bertram disc mill. [3] [4] This mill is essentially similar to the previous one, but the movement of the fixed discs was accomplished in it by means of four screws driven through a worm gear. [5] [6] Grinding knives were made of bronze or acid-resistant steel. The inside of the mill was lined with copper or acid-resistant steel. The capacity of the mill was 24-50 tons per day.
Over the course of more than a century of evolution, a number of very different types of disc mills have been developed. Over time, grinding discs became predominantly made of sandstone and some other rocks. It was not until after World War II that they returned to making grinding discs out of metal again.
Typical applications for a single-disc mill are all three stages of the wet milling of field corn, manufacture of peanut butter, processing nut shells, ammonium nitrate, urea, producing chemical slurries and recycled paper slurries, and grinding chromium metal.
Double-disc mills are typically used for alloy powders, aluminum chips, bark, barley, borax, brake lining scrap, brass chips, sodium hydroxide, chemical salts, coconut shells, copper powder, cork, cottonseed hulls, pharmaceuticals, feathers, hops, leather, oilseed cakes, phosphates, rice, rosin, sawdust, and seeds.
Disc mills are relatively expensive to run and maintain and they consume much more power than other shredding machines, and are not used where ball mills or hammermills produce the desired results at a lower cost.
Substances are crushed between the edge of a thick, spinning disk and something else. Some mills cover the edge of the disk in blades to chop up incoming matter rather than crush it.
Millstones or mill stones are stones used in gristmills, used for triturating, crushing or, more specifically, grinding wheat or other grains. They are sometimes referred to as grindstones or grinding stones.
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, sand or rock dust.
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.
A paper machine is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.
A ball mill is a type of grinder filled with grinding balls, used to grind or blend materials for use in mineral dressing processes, paints, pyrotechnics, ceramics, and selective laser sintering. It works on the principle of impact and attrition: size reduction is done by impact as the balls drop from near the top of the shell.
A mill is a device, often a structure, machine or kitchen appliance, that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand or by animals, working animal, wind (windmill) or water (watermill). In modern era, they are usually powered by electricity.
A hammer mill is a mill whose purpose is to shred or crush aggregate material into smaller pieces by the repeated blows of small hammers. These machines have numerous industrial applications, including:
Olive oil extraction is the process of extracting the olive oil present in olive drupes. Olive oil is produced in the mesocarp cells, and stored in a particular type of vacuole called a lipo vacuole, i.e., every cell contains a tiny olive oil droplet. Olive oil extraction is the process of separating the oil from the other fruit contents. It is possible to attain this separation by physical means alone, i.e., oil and water do not mix, so they are relatively easy to separate. This contrasts with other oils that are extracted with chemical solvents, generally hexane. The first operation when extracting olive oil is washing the olives, to reduce the presence of contaminants, especially soil which can create a particular flavor effect called "soil taste".
Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine.
A brush or carbon brush is an electrical contact, often made from specially prepared carbon, which conducts current between stationary and rotating parts of an electrical machine. Typical applications include electric motors, alternators and electric generators. The lifespan of a carbon brush depends on how much the motor is used, and how much power is put through the motor.
A pulverizer or grinder is a mechanical device for the grinding of many different types of materials. For example, a pulverizer mill is used to pulverize coal for combustion in the steam-generating furnaces of coal power plants.
A stump grinder is a machine designed to remove tree stumps by using a rotating cutting disc that chips away the wood. The machine typically features a cutter wheel with fixed carbide teeth. The cutter wheel's movements are controlled by hydraulic cylinders, which allow it to move laterally and vertically to grind through the stump.
A Hollander beater is a machine developed by the Dutch in 1680 to produce paper pulp from cellulose containing plant fibers. It replaced stamp mills for preparing pulp because the Hollander could produce in one day the same quantity of pulp it would take a stamp mill eight days to prepare.
Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool.
Surface grinding is done on flat surfaces to produce a smooth finish.
A vacuum ceramic filter is designed to separate liquids from solids for dewatering of ore concentrates purposes. The device consists of a rotator, slurry tank, ceramic filter plate, distributor, discharge scraper, cleaning device, frame, agitating device, pipe system, vacuum system, automatic acid dosing system, automatic lubricating system, valve and discharge chute. The operation and construction principle of vacuum ceramic filter resemble those of a conventional disc filter, but the filter medium is replaced by a finely porous ceramic disc. The disc material is inert, has a long operational life and is resistant to almost all chemicals. Performance can be optimized by taking into account all those factors which affect the overall efficiency of the separation process. Some of the variables affecting the performance of a vacuum ceramic filter include the solid concentration, speed rotation of the disc, slurry level in the feed basin, temperature of the feed slurry, and the pressure during dewatering stages and filter cake formation.
Roller mills are mills that use cylindrical rollers, either in opposing pairs or against flat plates, to crush or grind various materials, such as grain, ore, gravel, plastic, and others. Roller grain mills are an alternative to traditional millstone arrangements in gristmills. Roller mills for rock complement other types of mills, such as ball mills and hammermills, in such industries as the mining and processing of ore and construction aggregate; cement milling; and recycling.
Vertical roller mill is a type of grinder used to grind materials into extremely fine powder for use in mineral dressing processes, paints, pyrotechnics, cements and ceramics. It is an energy efficient alternative for a ball mill.
The IsaMill is an energy-efficient mineral industry grinding mill that was jointly developed in the 1990s by Mount Isa Mines Limited and Netzsch Feinmahltechnik ("Netzsch"), a German manufacturer of bead mills. The IsaMill is primarily known for its ultrafine grinding applications in the mining industry, but is also being used as a more efficient means of coarse grinding. By the end of 2008, over 70% of the IsaMill's installed capacity was for conventional regrinding or mainstream grinding applications, with target product sizes ranging from 25 to 60 μm.
Mechanical pulping is the process in which wood is separated or defibrated mechanically into pulp for the paper industry.