# Comminution

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Reduction of solid materials to a smaller average particle size

Mineral [crusher](/source/Crusher) *(left)* used in 19th century [Cornwall](/source/Cornwall) for comminution of tin ore; driven by [water mill](/source/Water_mill) *(right)*

**Comminution** is the reduction of [solid](/source/Solid) [materials](/source/Material) from one average [particle size](/source/Particle_size) to a smaller average particle size, by [crushing](/source/Crusher), [grinding](/source/Mill_(grinding)), [cutting](/source/Cutting), [vibrating](/source/Vibrator_(mechanical)), or other processes.[1] Comminution is related to **pulverization** and **grinding**. All use mechanical devices, and many types of [mills](/source/Mill_(grinding)) have been invented. Concomitant with size reduction, comminution increases the surface area of the solid.

For example, a pulverizer mill is used to [pulverize coal](/source/Pulverized_coal-fired_boiler) for [combustion](/source/Combustion) in the steam-generating furnaces of [coal power plants](/source/Coal-fired_power_station). A [cement mill](/source/Cement_mill) produces finely ground ingredients for [portland cement](/source/Portland_cement).[2] A hammer mill is used on farms for grinding grain and chaff for animal feed. A demolition pulverizer is an attachment for an excavator to break up large pieces of concrete. Comminution is important in [mineral processing](/source/Mineral_processing), where rocks are broken into small particles to help liberate the ore from [gangue](/source/Gangue).[3] Comminution or grinding is also important in [ceramics](/source/Ceramic), [electronics](/source/Electronics), and battery research.[4] [Mechanical pulping](/source/Mechanical_pulping) is a traditional way for [paper making](/source/Paper_making) from [wood](/source/Wood). The [mastication](/source/Mastication) of food involves comminution. From the perspective of [chemical engineering](/source/Chemical_engineering), comminution is a [unit operation](/source/Unit_operation).

In [geology](/source/Geology), comminution refers to a natural process during [faulting](/source/Fault_(geology)) in the upper part of the [Earth's crust](/source/Crust_(geology)#Earth's_crust).[5]

## Energy requirements

The comminution of solid materials consumes energy.[6] Approximately 65% of the power for the production of cement is consumed in comminution.[7]

The comminution energy can be estimated by:

- [Rittinger's law](/source/Peter_von_Rittinger), which assumes that the energy consumed is proportional to the newly generated surface area;[8]

- [Kick's law](https://en.wikipedia.org/w/index.php?title=Kick%27s_law&action=edit&redlink=1), which related the energy to the sizes of the feed particles and the product particles;[9]

- [Bond's law](/source/Fred_Chester_Bond), which assumes that the total work useful in breakage is inversely proportional to the square root of the diameter of the product particles, [implying] theoretically that the work input varies as the length of the new cracks made in breakage.[10][11]

- [Holmes's law](https://en.wikipedia.org/w/index.php?title=Holmes%27s_law&action=edit&redlink=1), which modifies Bond's law by substituting the square root with an exponent that depends on the material.[6]

Three forces are typically used to effect the comminution of particles: [impact](/source/Impact_(mechanics)), [shear](/source/Shear_stress), and [compression](/source/Compression_(physical)).

## Methods

Diagram of [froth flotation](/source/Froth_flotation) cell used to process ores after communition. A mixture of ore and water called pulp [1] enters the cell from a conditioner, and flows to the bottom of the cell. Air [2] or nitrogen is passed down a vertical impeller where shearing forces break the air stream into small bubbles. The mineral concentrate froth is collected from the top of the cell [3], while the pulp [4] flows to another cell.

Idealized image of [chemical mechanical polishing](/source/Chemical_mechanical_polishing), a kind of grinding.[12]

There are several methods of comminution. Comminution of solid materials requires various types of [crushers](/source/Crusher) and [mills](/source/Mill_(grinding)) depending on the feed properties such as hardness at various size ranges and application requirements such as throughput and maintenance. The most common machines for the comminution of coarse feed material (primary crushers) are the [jaw crusher](/source/Jaw_crusher) (1m > P80 > 100 mm), [cone crusher](/source/Crusher#Cone_crusher) (P80 > 20 mm) and [hammer crusher](/source/Hammer_crusher). Primary crusher products in intermediate feed particle size ranges (100mm > P80 > 20mm) can be ground in [autogenous](/source/Mill_(grinding)#Autogenous_mill) (AG) or [semi-autogenous](/source/Mill_(grinding)#SAG_mill) (SAG) mills depending on feed properties and application requirements. For comminution of finer particle size ranges (20mm > P80 > 30 μm) machines like the ball mill, vertical roller mill, hammer mill, roller press or high compression roller mill, vibration mill, [jet mill](/source/Jet_mill) and others are used. For yet finer grind sizes (sometimes referred to as "ultrafine grinding"), specialist mills such as the [IsaMill](/source/IsaMill) are used.

[Trituration](/source/Trituration), for instance, is comminution (or substance breakdown) by rubbing. Furthermore, methods of trituration include levigation, which is the trituration of a powder with a non-solvent liquid, and pulverization by intervention, which is trituration with a solvent that can be easily removed after the substance has been broken down.

## See also

- [Mill (grinding)](/source/Mill_(grinding)) – Device that breaks solid materials into smaller pieces by grinding, crushing, or cutting

- [Particle size distribution](/source/Particle_size_distribution) – Function representing relative sizes of particles in a systemPages displaying short descriptions of redirect targets

- [Crusher](/source/Crusher) – Machine designed to reduce large objects into smaller ones

- [Electromagnetic vortex intensifier with ferromagnetic particles](/source/Electromagnetic_vortex_intensifier_with_ferromagnetic_particles) - Special equipment for ultrafine grinding

- [Burr mill](/source/Burr_mill)

## External links

- [Roller Coal Mills](https://web.archive.org/web/20110421040839/http://www.rollermill.net/ore-mill/roller-coal-mills.html), via Internet Archive

- Gupty, Chiranjib Kumar (2003). [*Chemical Metallurgy*](https://books.google.com/books?id=2PAarkWieIQC&q=comminution&pg=PA130). Wiley-VCH Verlag. p. 130. [ISBN](/source/ISBN_(identifier)) [9783527605255](https://en.wikipedia.org/wiki/Special:BookSources/9783527605255). Retrieved August 22, 2010.

## References

1. **[^](#cite_ref-1)** Bernotat, Siegfried; Schönert, Klaus (2000). "Size Reduction". *Ullmann's Encyclopedia of Industrial Chemistry*. [doi](/source/Doi_(identifier)):[10.1002/14356007.b02_05](https://doi.org/10.1002%2F14356007.b02_05). [ISBN](/source/ISBN_(identifier)) [978-3-527-30385-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-30385-4).

1. **[^](#cite_ref-2)** Sprung, Siegbert (2008). "Cement". *Ullmann's Encyclopedia of Industrial Chemistry*. [doi](/source/Doi_(identifier)):[10.1002/14356007.a05_489.pub2](https://doi.org/10.1002%2F14356007.a05_489.pub2). [ISBN](/source/ISBN_(identifier)) [978-3-527-30385-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-30385-4).

1. **[^](#cite_ref-3)** Sadri, Farzaneh; Nazari, Amir Mohammad; Ghahreman, Ahmad (2017). "A Review on the Cracking, Baking and Leaching Processes of Rare Earth Element Concentrates". *Journal of Rare Earths*. **35** (8): 739–752. [Bibcode](/source/Bibcode_(identifier)):[2017JREar..35..739S](https://ui.adsabs.harvard.edu/abs/2017JREar..35..739S). [doi](/source/Doi_(identifier)):[10.1016/s1002-0721(17)60971-2](https://doi.org/10.1016%2Fs1002-0721%2817%2960971-2).

1. **[^](#cite_ref-4)** Yang, Yuan; Zheng, Guangyuan; Cui, Yi (2013). "Nanostructured Sulfur Cathodes". *Chemical Society Reviews*. **42** (7): 3018–3032. [doi](/source/Doi_(identifier)):[10.1039/c2cs35256g](https://doi.org/10.1039%2Fc2cs35256g). [PMID](/source/PMID_(identifier)) [23325336](https://pubmed.ncbi.nlm.nih.gov/23325336).

1. **[^](#cite_ref-Sibson_5-0)** Sibson, R.H. (1986). ["Earthquakes and rock deformation in crustal fault zones"](http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1986AREPS..14..149S&letter=0&classic=YES&defaultprint=YES&whole_paper=YES&page=149&epage=149&send=Send+PDF&filetype=.pdf) (PDF). *Annual Review of Earth and Planetary Sciences*. **14**: 156. [Bibcode](/source/Bibcode_(identifier)):[1986AREPS..14..149S](https://ui.adsabs.harvard.edu/abs/1986AREPS..14..149S). [doi](/source/Doi_(identifier)):[10.1146/annurev.ea.14.050186.001053](https://doi.org/10.1146%2Fannurev.ea.14.050186.001053). Retrieved 2 July 2011.

1. ^ [***a***](#cite_ref-Kanda_and_Kotake_2007_6-0) [***b***](#cite_ref-Kanda_and_Kotake_2007_6-1) Kanda, Yoshiteru; Kotake, Naoya (2007). "Chapter 12: Comminution Energy and Evaluation in Fine Grinding". In Salman, Agba D.; Hounslow, Michael J. (eds.). [*Handbook of Powder Technology, Volume 12: Particle breakage*](https://books.google.com/books?id=sPk0OhP_brIC&q=comminution&pg=PA530). Elsevier. pp. 529–551. [ISBN](/source/ISBN_(identifier)) [9780080553467](https://en.wikipedia.org/wiki/Special:BookSources/9780080553467). Retrieved August 20, 2010.

1. **[^](#cite_ref-7)** Sohoni, S.; Sridhar, R.; Mandal, G. (1991). "The effect of grinding aids on the fine grinding of limestone, quartz and Portland cement clinker". *Powder Technology*. **67** (3): 277–286. [doi](/source/Doi_(identifier)):[10.1016/0032-5910(91)80109-V](https://doi.org/10.1016%2F0032-5910%2891%2980109-V).

1. **[^](#cite_ref-Jankovic_et_al_2010_8-0)** Jankovic, A.; Dundar, H.; Mehta, R. (March 2010), ["Relationships between comminution energy and product size for a magnetite ore"](https://web.archive.org/web/20130306164447/http://metso.com/miningandconstruction/mct_service.nsf/WebWID/WTB-120106-22576-209D0/$File/021.pdf) (PDF), *Journal of the Southern African Institute of Mining and Metallurgy*, **110**: 141–146, archived from [the original](http://www.metso.com/miningandconstruction/mct_service.nsf/WebWID/WTB-120106-22576-209D0/$File/021.pdf) (PDF) on 2013-03-06, retrieved 2015-06-16.

1. **[^](#cite_ref-9)** Kick, F.M. Das Gesetz der proportionalen Widerstände und seine anwendung felix. Leipzig, Germany. 1885.

1. **[^](#cite_ref-10)** Bond, Fred C. (1975) *It Happened to Me*, Ch. 130. Amazon.com. Retrieved May 29, 2011.

1. **[^](#cite_ref-11)** Bond, F.C. The third theory of comminution.Trans. AIME, vol. 193, 1952. pp. 484–494.

1. **[^](#cite_ref-12)** Mahadevaiyer Krishnan, Jakub W. Nalaskowsk, and Lee M. Cook, "Chemical Mechanical Planarization: Slurry Chemistry, Materials, and Mechanisms" Chem. Rev., 2010, vol. 110, pp 178–204. [doi](/source/Doi_(identifier)):[10.1021/cr900170z](https://doi.org/10.1021%2Fcr900170z)

v t e Extractive metallurgy Metallurgical assay Non-ferrous extractive metallurgy Mineral processing (by physical means) Extraction Geological survey Natural resources Ore Economic geology Mineral Base metal Precious metal Mining Surface Underground in hard rock Underground in soft rock Recycling Scrap Comminution Stamp mill Arrastra Crusher AG mill SAG mill Pebble mill Ball mill Rod mill IsaMill Sizing Ore sorting Vanning Hydrocyclone Trommel Cyclonic separation Gyratory equipment Mechanical screening Concentration Froth flotation Jameson cell Panning Jig concentrators Gravity Concentration Magnetic separation (Magnetation) Rocker box Dry washing Buddle pit Pyrometallurgy (by heat) Smelting Iron smelting Lead smelting Zinc smelting Flash smelting ISASMELT furnace Refractory linings Refining Cupellation Parkes process Bottom-blown oxygen converter Poling IsaKidd process Other Calcination Roasting Liquation Hydrometallurgy (by aqueous solution) Leaching Lixiviant Heap leaching Dump leaching Tank leaching In situ leaching Gold chlorination Gold cyanidation Bayer process Amalgamation Patio process Pan amalgamation Electrometallurgy (by electricity) Electrolysis Electrowinning Hall–Héroult process Castner process Downs cell Co-products Tailings Gangue Slag Clinker Chat Red mud Stamp sand

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Adapted from the Wikipedia article [Comminution](https://en.wikipedia.org/wiki/Comminution) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Comminution?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.