The Frank–Caro process, also called cyanamide process, is the

nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

reaction of

calcium carbide Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of Ca C2. Its main use industrially is in the production of acetylene and calcium cyanamide. The pure material is colorless, while pieces of te ...

with

nitrogen gas Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh ...

in a reactor vessel at about 1,000 °C. The reaction is exothermic and self-sustaining once the reaction temperature is reached. Originally the reaction took place in large steel cylinders with an electrical resistance element providing initial heat to start the reaction. Modern production uses rotating ovens. The synthesis produces a solid mixture of

calcium cyanamide Calcium cyanamide is the inorganic compound with the formula CaCN2. It is the calcium salt of the cyanamide () anion. This chemical is used as fertilizer and is commercially known as nitrolime. It was first synthesized in 1898 by Adolph Frank and ...

(CaCN₂), also known as nitrolime, and

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

. :CaC₂ + N₂ → CaCN₂ + C

History

The Frank–Caro process was the first commercial process that was used worldwide to fix atmospheric nitrogen. The product was used as

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

and commercially known as ''Lime-Nitrogen''. ''Nitrolim'' or ''Kalkstickstoff'' in German. The method was developed by the German chemists Adolph Frank and Nikodem Caro between 1895 and 1899. In its first decades, the world market for inorganic fertilizer was dominated by factories utilizing the cyanamide process.

Production facilities

The first full-scale factories were established in 1905 in Piano d´Orta (Italy) and Westeregeln (Germany). From 1908 the Frank–Caro process was used at ''North Western Cyanamide Company'' at Odda, Norway. With an annual production capacity of 12,000 ton from 1909, the factory at Odda was by far the largest in the world. At this time, first phase factories were established in

Briançon Briançon (, ) is the sole subprefecture of the Hautes-Alpes department in the Provence-Alpes-Côte d'Azur region in Southeastern France. It is the highest city in France at an altitude of , based on the national definition as a community cont ...

(France),

Martigny Martigny (; german: Martinach, ; la, Octodurum) is the capital city of the district of Martigny, canton of Valais, Switzerland. It lies at an elevation of , and its population is approximately 15000 inhabitants (''Martignerains'' or "Octoduriens ...

(Switzerland), Bromberg (

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

) and

Knapsack A backpack—also called knapsack, schoolbag, rucksack, rucksac, pack, sackpack, booksack, bookbag or backsack—is, in its simplest frameless form, a fabric sack carried on one's back and secured with two straps that go over the shoulders ...

(Germany). The cyanamide factory at Odda ceased operation in 2002. It is still intact and is a Norwegian candidate to the

UNESCO World Heritage List A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

Haber process

In the 1920s the more energy-efficient

Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation process and is the main industrial procedure for the production of ammonia today. It is named after its inventors, the German chemists Fritz Haber and ...

gradually took over. In 1945 the production of calcium cyanamide reached a peak of an estimated 1.5 million tons a year.

Patent

German patent nr. DE 88363 (1895)

References

External links