Calcination is the process of heating a substance to a high temperature, but below its melting or fusing point, to bring about thermal decomposition or a phase transition in its physical or chemical constitution. The process, which usually takes place in long cylindrical kilns, often has the effect of making a substance friable. The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The standard enthalpy change of fusion, also known as the heat of fusion, is the amount of thermal energy which must be absorbed or lost for 1 gram of a substance to change states from a solid to a liquid or vice versa. ... Thermal decomposition is a chemical reaction where a single compound breaks up into two or more simpler compounds or elements when heated. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... Charcoal Kilns, California Gold Kiln, Victoria, Australia Hop kiln. ... This page is a candidate to be copied to Wiktionary using the Transwiki process. ...

The objects of calcination are usually:

• to drive off water, present as absorbed moisture, as "water of crystallization", or as "water of constitution" (as in the conversion of ferric hydroxide to ferric oxide);
• to drive off carbon dioxide (as in the calcination of limestone into lime in a limekiln), sulfur dioxide, or other volatile constituent;
• to oxidize (oxidative calcination) a part or the whole of the substance (commonly used to convert metal sulfide ores to oxides in the first step of recovering such metals as zinc, lead, and copper);
• the reduction (reductive calcination) of metals from their ores (smelting).

There are a few other purposes for which calcination is employed in special cases (e.g. bone char). Water of crystallization is water that is tightly associated with crystalline metal salts, and remains after drying in a fixed proportion to the salt. ... Iron(III) oxide - also known as ferric oxide, red iron oxide, synthetic maghemite, rouge,or rust - is one of several oxide compounds of iron, and is most notable for its ferromagnetic properties. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Limey shale overlaid by limestone. ... Lime is a general term for various naturally occurring minerals and materials derived from them in which carbonates, oxides and hydroxides of calcium predominate. ... A 19th century limekiln A limekiln is a kiln used to produce quicklime by the calcination of limestone (calcium carbonate). ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... Volatile organic compounds (VOCs) are organic chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere. ... To oxidize an element or a compound is to increase its oxidation number. ... The term sulfide (sulphide in British) refers to several types of chemical compounds containing sulfur in its lowest oxidation number of -2. ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Atomic mass 65. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic brown Atomic mass 63. ... Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... Chemical reduction, or smelting, is a form of extractive metallurgy. ... Bone char, also known as bone black or animal charcoal, is a granular black material produced by calcinating animal bones: the bones are heated to high temperatures in the absence of air to drive off volatile substances. ...

Calcination reactions may include thermal dissociation, including the destructive distillation of organic compounds (i.e., heating a highly carbonaceous material in the absence of air or oxygen, to produce solids, liquids, and gases). Examples of other calcination reactions include the concentration of alumina by heating bauxite; polymorphic phase transitions such as the conversion of anatase to the rutile; and thermal recrystallizations such as the devitrification of glass. Materials that are commonly calcined include phosphate, aluminum oxide, manganese carbonate, petrol coke, and sea water magnesite. Dissociation in chemistry and biochemistry is a general process in which complexes, molecules, or salts separate or split into smaller molecules, ions, or radicals, usually in a reversible manner. ... Destructive Distillation means driving off (and collecting) gas from some matter by heating it in the absence of air, where pyrolysis occurs during heating. ... This article belongs in one or more categories. ... Aluminium oxide (or aluminum oxide) (Al2O3) is a chemical compound of aluminium and oxygen. ... Bauxite with penny Bauxite (pebbly) Bauxite is a naturally occurring, heterogeneous material composed primarily of one or more aluminium hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminium silicates, and other impurities in minor or trace amounts. ... In general, polymorphism describes multiple possible states for a single property (it is said to be polymorphic). ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... Anatase is one of the three mineral forms of titanium dioxide. ... Rutile in trellis texture characteristic of secondary rutile. ... Recrystallization is an essentially physical process that has meanings in chemistry and geology. ... In inorganic chemistry, a phosphate is a salt of phosphoric acid. ... Aluminium oxide (or aluminum oxide) (Al2O3) is a chemical compound of aluminium and oxygen. ... Manganese(II)Carbonate is a very slightly soluble carbonate. ... Petroleum coke is a carbonaceous solid derived from oil refinery cracking processes. ... Magnesite is magnesium carbonate, MgCO3. ...

Alchemy

In alchemy, calcination was believed to be one of the 12 vital processes required for the transformation of a substance. For other uses, see Alchemy (disambiguation). ...

Alchemists distinguished two kinds of calcination, actual and potential. Actual calcination is that brought about by actual fire, from wood, coals, or other fuel, raised to a certian temperature. Potential calcination is that brought about by potential fire, such as corrosive chemicals; for example, gold was calcined in a reverberatory furnace with mercury and sal ammoniac; silver with common salt and alkali salt; copper with salt and sulfur; iron with sal ammoniac and vinegar; tin with antimony; lead with sulfure; and mercury with aqua fortis. ^[1] A reverbatory furnace is a metallurgical or process furnace which characteristically isolates the material being processed from contact with the fuel, but not from contact with the combustion gases. ... Sal ammoniac is a rare mineral composed of ammonium chloride, NH4Cl. ... The chemical compound nitric acid (HNO3), otherwise known as aqua fortis, is a colorless, corrosive liquid, a toxic acid which can cause severe burns. ...

There was also philosophical calcination, which was said to occur when horns, hooves, etc, were hung over boiling water, or other liquor, till they had lost their mucilage, and were easily reducible into powder. ^[1]

Popular culture

In the Bethesda Softworks games Morrowind and Oblivion, an alchemical tool called a Calcinator was said to burn substances to ash, increasing the potency of mixtures. The end result of using a Calcinator would be increased potency of all alchemical potions, regardless of their positive or negative effects. Bethesda Softworks LLC, a ZeniMax Media Company, is a developer and publisher of computer and video games. ... The Elder Scrolls III: Morrowind (aka Morrowind) is a computer role-playing game by Bethesda Softworks, and the third in The Elder Scrolls series of games. ... Look up oblivion in Wiktionary, the free dictionary. ...

See also

• philosophical calcination

References

1. ^ ^a b This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.