Caking is a powder's tendency to form lumps or masses. The formation of lumps interferes with packaging, transport, flowability, and consumption. Usually caking is undesirable, but it is useful when pressing powdered substances into pills or

briquette A briquette (; also spelled briquet) is a compressed block of coal dust or other combustible biomass material (e.g. charcoal, sawdust, wood chips, peat, or paper) used for fuel and kindling to start a combustion, fire. The term is a diminutive der ...

Granular material A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when granulation, grains collide). T ...

s can also be subject to caking, particularly those that are

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

such as salt, sugar, and many

chemical fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrition, plant nutrients. Fertilizers may be distinct from Liming (soil), liming materials or other non- ...

Anticaking agent An anticaking agent is an additive placed in powdered or granulated materials, such as table salt or confectioneries, to prevent the formation of lumps ( caking) and for easing packaging, transport, flowability, and consumption. Caking mechanism ...

s are commonly added to control caking. Caking properties must be considered when designing and constructing bulk material handling equipment. Powdered substances that need to be stored, and flow smoothly at some time in the future, are often pelletized or made into

pill Pill or The Pill may refer to: Drugs * Pill (pharmacy), referring to anything small for a specific dose of medicine * "The Pill", a general nickname for the combined oral contraceptive pill Film and television * ''The Pill'' (film), a 2011 fil ...

Mechanism

Caking mechanisms depend on the nature of the material. Caking is a consequence of chemical reactions of grain surfaces. Often these reactions involve adsorption of water vapor or other gases. Crystalline solids often cake by formation of liquid bridge between microcrystals and subsequent fusion of a solid bridge. Amorphous materials can cake by

glass transition The glass–liquid transition, or glass transition, is the gradual and Reversible reaction, reversible transition in amorphous solid, amorphous materials (or in amorphous regions within Crystallinity, semicrystalline materials) from a hard and rel ...

s and changes in viscosity. Polymorphic

phase transition In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta ...

s can also induce caking. The caking process can involve electrostatic attractions or the formation of weak

chemical bond A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons a ...

s between particles. Charcoal Briquette

Anticaking agents

Anticaking agents are chemical compounds that prevent caking. Some anticaking agents function by absorbing excess moisture or by coating particles and making them water-repellent.

Calcium silicate Calcium silicate can refer to several silicates of calcium including: *CaO·SiO2, wollastonite (CaSiO3) *2CaO·SiO2, larnite (Ca2SiO4) *3CaO·SiO2, alite or (Ca3SiO5) *3CaO·2SiO2, (Ca3Si2O7). This article focuses on Ca2SiO4, also known as calci ...

(CaSiO₃), a common anti-caking agent added to table salt, absorbs both water and oil. Anticaking agents are also used in non-food items such as

road salt Road salt (also known as de-icing salt, rock salt, or snow salt) is a salt used mainly as an anti-slip agent in winter road conditions, but also to prevent dust and snow build-up on roads. Various kinds of salts are used as road salt, but calciu ...

fertiliser A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrition, plant nutrients. Fertilizers may be distinct from Liming (soil), liming materials or other non- ...

cosmetics Cosmetics are substances that are intended for application to the body for cleansing, beautifying, promoting attractiveness, or altering appearance. They are mixtures of chemical compounds derived from either Natural product, natural source ...

, synthetic

detergent A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...

s, and in manufacturing applications. {{wikt

References

Chemical engineering Particle technology