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 (e.g., via a hand crank), working animal (e.g., horse mill), wind ( windmill) or water ( watermill). In modern era, they are usually powered by electricity.

In materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces at the grain size level. See also crusher for mechanisms producing larger particles. In general, grinding processes require a relatively large amount of energy; for this reason, an experimental method to measure the energy used locally during milling with different machines was recently proposed. [5] Autogenous mill [ edit ] O'Sullivan, Muiris; Downey, Liam (2006). "Quern Stones". Archaeology Ireland. 20 (2): 22–25. JSTOR 20559139. A high pressure grinding roll, often referred to as HPGRs or roller press, consists out of two rollers with the same dimensions, which are rotating against each other with the same circumferential speed. The special feeding of bulk material through a hopper leads to a material bed between the two rollers. The bearing units of one roller can move linearly and are pressed against the material bed by springs or hydraulic cylinders. The pressures in the material bed are greater than 50 MPa (7,000 PSI). In general they achieve 100 to 300 MPa. By this the material bed is compacted to a solid volume portion of more than 80%. You also want to avoid heating the flour. Milling is a violent business, and some amount of friction is inevitable, regardless what type of mill you’re using. But overheating your flour isn’t. Heat not only destroys the nutrients and flavorful molecules in flour, but it can also degrade gluten-forming proteins, potentially leaving the flour useless for breadmaking. (There is some dispute as to how hot is too hot for flour—some sources say to avoid temperatures over 115˚F, others say the flour can hit 140˚F before much damage occurs.)McLaren D, Hunter F (2008). "New aspects of rotary querns in Scotland". Proc Soc Antiq Scot. 138: 122–125. ISSN 0081-1564.

a b c Freese, Stanley (27 May 2011). Windmills and millwrighting. Cambridge University Press. p.14. ISBN 9781107600133. Anna Revedin et al. (2010). "Thirty thousand-year-old evidence of plant food processing". Proceedings of the National Academy of Sciences, vol. 107, no. 44, pp. 18815–18819 (18815) Wills, B.A. (2006). Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery. Vol.7th ed. Amsterdam, Boston, MA. p.157. ISBN 0750644508.fr) Jean-Pierre Brun. Archéologie du vin et de l'huile dans l'Empire romain. Éditions errance, 2004 (ISBN 2-87772-293-7) We don't really know how the Greeks processed their cereals between the 1st and 4th centuries. The "blood" mill was undoubtedly widespread, as attested by the legend of Lucius' donkey, borrowed by Lucian of Samosata and Apuleius. The coexistence of several types of milling seems to be the rule in the Aegean world, and the codification of Diocletian's edict in the 2nd century, which established three types of mills (hand, blood, and water), can still be found in the Byzantine rural code in the 6th century, and even in travellers' accounts in the 17th century. [30]