PRODUCTS

CALCIUM CYANAMIDE

Calcium cyanamide, also known as Calcium carbondiamide, Calcium cyan-2°-amide or Calcium cyanonitride is the inorganic compound with the formula CaCN2.
Calcium cyanamide is the calcium salt of the cyanamide (CN2−2) anion.
Calcium cyanamide is used as fertilizer and is commercially known as nitrolime.
Calcium cyanamide also has herbicidal activity and in the 1950s was marketed as cyanamid.
Calcium cyanamide was first synthesized in 1898 by Adolph Frank and Nikodem Caro (Frank–Caro process).

CAS: 156-62-7
European Community (EC) Number: 205-861-8

Color / Form: Pure calcium cyanamide occurs as glistening, hexagonal crystals belonging to the rhombohedral system
Boiling Point: Sublimes >2102 °F
Melting Point: 2372 °F
Solubility: Decomposes
Density: 2.29 at 68 °F
Vapor Pressure: 0 mmHg

Calcium cyanamide is used as a fertilizer, defoliant, herbicide, fungicide, and pesticide; in the manufacture and refining of iron; and in the manufacture of calcium cyanide, melamine, and dicyandiamide.

The chemical formula for calcium cyanamide is CCaN2, and its molecular weight is 80.11 g/mol.
Commercial grades of calcium cyanamide occur as grayish-black lumps of powder.
Pure calcium cyanamide occurs as glistening hexagonal crystals that are insoluble in water.
The odor threshold for calcium cyanamide has not been established.

Limestone, coal and atmospheric nitrogen are the natural raw materials from which calcium cyanamide is manufactured.
Regular investment and constant improvement of the production process ensures a modern, efficient and environmentally friendly manufacture of the specialty fertilizer.

Calcium cyanamide is manufactured in three stages:

Stage one: Manufacture of burnt lime (also known as quick lime)
Limestone (CaCO3), mined from natural deposits, is crushed and then processed in coke or oil-fired furnaces to form burnt lime.

Stage two: Manufacture of carbide
The burnt lime obtained as a result of this process is fed into carbide furnaces together with coke and anthracite, which provide a supply of carbon.
Calcium carbide is produced in these ovens at temperatures above 2,000°C, with electrical energy generating the heat required.
The carbon monoxide generated during this manufacturing process is collected and used as a starting material for further chemical reactions.

Stage three: Manufacture of calcium cyanamide
In the last stage of the synthesis nitrogen gas is passed through finely-ground calcium carbide which has a temperature of approx. 1,100°C.
This chemically binds the nitrogen, resulting in calcium cyanamide.
The carbon released during this reaction gives the calcium cyanamide its black color.
The nitrogen gas necessary is recovered in a proprietary air separation plant using the Linde method.

The so-called technical calcium cyanamide coming from the rotary kilns is further processed for use in agriculture and horticulture.
The ground-calcium cyanamide is produced by finely grinding the product.
Pearled calcium cyanamide is produced from the ground product by granulation, and adjusted to the defined grain size by sieving.

Calcium cyanamide (CaCN2) has been used in agriculture for more than a century as a nitrogen fertilizer with nitrification inhibiting and pest-controlling characteristics.

Characteristics

- Less run off from soil.
- With slow release, the number and quantity of fertilizer applications can be reduced.
- Can be used to remedy soil acidity.
- The organic biodegradation process is promoted enabling soil to be loosened.

Uses
- As a fertilizer – an increase in the yield/quality of individual crops can be targeted.
- As an agricultural chemical - it is effective against a wide range of harmful insects (and weeds) as indicated on the bag.
- Promote biodegradation - it should be added to rice/wheat straw when these are put under the soil.
- Soil improvement – can remedy soil acidity.

The main use of calcium cyanamide is in agriculture as a fertilizer.
In contact with water, Calcium cyanamide hydrolyses into hydrogen cyanamide which decomposes and liberates ammonia:

CaCN2 + 3 H2O → 2 NH3 + CaCO3

It was used to produce sodium cyanide by fusing with sodium carbonate:

CaCN2 + Na2CO3 + 2 C → 2 NaCN + CaO + 2 CO

Sodium cyanide is used in cyanide process in gold mining.
It can also be used in the preparation of calcium cyanide and melamine.

Through hydrolysis in the presence of carbon dioxide, calcium cyanamide produces cyanamide:

CaCN2 + H2O + CO2 → CaCO3 + H2NCN

The conversion is conducted in slurries.
For this reason, most commercial calcium cyanamide is sold as an aqueous solution.

Thiourea can be produced by the reaction of hydrogen sulfide with calcium cyanamide in the presence of carbon dioxide.

Calcium cyanamide is also used as a wire-fed alloy in steelmaking to introduce nitrogen into the steel.

Calcium cyanamide, also known as nitrolime, has been used as slow release nitrogen / calcium fertiliser with liming effect for over 100 years.
Because of its negative effect on many soil borne diseases it is now often applied to prevent yield and quality losses during increasingly tight crop rotations.

Calcium cyanamide is a very special fertilizer.
Calcium cyanamide not only supplies the soil with nitrogen and lime but it also offers a range of other unique special effects.
Many farmers insist on calcium cyanamide in order to prevent yield and quality losses during increasingly tight crop rotations, or to be able to manage them properly once again.
Why? – because soil health is more important than ever to ensure sustainable production.

Discovered more than 100 years ago, calcium cyanamide was the first mineral fertilizer to enable atmospheric nitrogen to be used for plant nutrition.
Today the multipurpose fertilizer still plays an important role in crop cultivation, because calcium cyanamide is the only fertilizer that contains the nutrient element nitrogen in the so-called NCN binding form.
This helps ensure that plants are supplied with nitrogen over a longer time period as and when needed.
Fertilizing with calcium cyanamide also increases the biological activity of the soil.

The second nutrient element that calcium cyanamide contains is calcium.
This is mostly water-soluble and so is immediately available to the plants.
Whereas other nitrogen fertilizers tend to make the soil more acid, calcium cyanamide improves the lime balance of the soil.
In sum, on soils that are fertilized with calcium cyanamide plants receive the ideal amount of nitrogen, the structure of the soil is improved through the addition of valuable lime, and the soil health is improved at the same time.

Production
Calcium cyanamide is prepared from calcium carbide.
The carbide powder is heated at about 1000 °C in an electric furnace into which nitrogen is passed for several hours.
Calcium cyanamide is cooled to ambient temperatures and any unreacted carbide is leached out cautiously with water.

CaC2 + N2 → CaCN2 + C (ΔHf = –69.0 kcal/mol at 25 °C)

Calcium cyanamide crystallizes in hexagonal crystal system with space group R3m and lattice constants a = 3.67 Å, c = 14.85 Å.

History
In their search for a new process for producing cyanides for cyanide leaching of gold, Frank and Caro discovered the ability of alkaline earth carbides to absorb atmospheric nitrogen at high temperatures.
Fritz Rothe, a colleague of Frank and Caro, succeeded in 1898 in overcoming problems with the use of calcium carbide and clarified that at around 1,100 °C not calcium cyanide but calcium cyanamide is formed in the reaction.
In fact, the initial target product sodium cyanide can also be obtained from calcium cyanamide by melting it with sodium chloride in the presence of carbon:

CaCN2 + 2 NaCl + C → 2 NaCN + CaCl2

Frank and Caro developed this reaction for a large-scale, continuous production process.
It was particularly challenging to implement because it requires precise control of high temperatures during the initial igniter step; the melting point of calcium cyanamide is only about 120°C lower than the boiling point of sodium chloride.

In 1901, Ferdinand Eduard Polzeniusz patented a process that converts calcium carbide to calcium cyanamide in the presence of 10% calcium chloride at 700 °C.
The advantage of this reaction temperature (lower by about 400 °C), however, must be weighed against the large amount of calcium chloride required and the discontinuous process control. Nevertheless, both processes (the Rothe–Frank–Caro process and the Polzeniusz–Krauss process) played a role in the first half of the 20th century.
In the record year 1945, a total of approximately 1.5 million tonnes was produced worldwide using both processes.
Frank and Caro also noted the formation of ammonia from calcium cyanamide.

CaCN2 + 3 H2O → 2 NH3 + CaCO3

Albert Frank recognized the fundamental importance of this reaction as a breakthrough in the provision of ammonia from atmospheric nitrogen and in 1901 recommended calcium cyanamide as a nitrogen fertilizer.
Between 1908 and 1919, five calcium cyanamide plants with a total capacity of 500,000 tonnes per year were set up in Germany, and one in Switzerland.
Calcium cyanamide was at the time the cheapest nitrogen fertilizer with additional efficacy against weeds and plant pests, and had great advantages over the nitrogen fertilizers that were conventional at the time.
However, the large-scale implementation of ammonia synthesis via the Haber process became a serious competitor to the very energy-intensive Frank–Caro process.
As urea (formed via the Haber–Bosch process) was significantly more nitrogen-rich (46% nitrogen compared to ca. 20%), cheaper, and faster acting, the role of calcium cyanamide was gradually reduced to a multifunctional nitrogen fertilizer for niche applications.
Other reasons for its loss of popularity were its dirty-black color, dusty appearance and irritating properties, as well as its inhibition of an alcohol-degrading enzyme which causes temporary accumulation of acetaldehyde in the body leading to dizziness, nausea, and alcohol flush reaction when alcohol is consumed around the time of bodily exposure.

Applications:

Waiting period:
If calcium cyanamide is to be spread before sowing or before planting the crops then the sowing or planting must wait until the fertilizer nitrogen in the soil is present in the form of urea or ammonium.
Conversion will only happen when conditions are moist.
Incorporating the calcium cyanamide to a shallow depth in the topsoil can speed up conversion.

Rule of thumb for the waiting period: 2 - 3 days per 100 kg/ha
If you are not sure please do a cress test(germination of cress seeds in a soil sample)!

Applying:
To ensure good plant compatibility and optimal use of the positive side effects the fertilizer should be spread evenly.
Working widths of up to 32 meters can be used, depending on the fertilizer spreader.
Please contact the manufacturer to enquire about the appropriate settings on the fertilizer spreader.

Top dressing:
With certain crops top dressing is also an option.
Exactly when this should be done depends on the growth and development stage of the plants, and differs from crop to crop.
For more precise details please refer to the recommendations for use with particular crops.

Water Protection:
Calcium cyanamide may be used in water protection areas.
Of course, in this case the amount of N should be adapted to the requirements of the crop and in compliance with existing regulations on nitrogen fertilization.
The amount of N has to be adapted to the requirement of the crop.
When calculating the demand for fertilization please take into account the soil’s contents of mineral nitrogen (Nmin).
All applications of calcium cyanamide Perlka have to be in compliance with the existing regulations on nitrogen fertilization.

What effect does calcium cyanamide have?

Effect on soil borne diseases
Calcium cyanamide when used as a fertiliser, offers good control of clubroot and some species of Phytophthora.
Other organisms causing soil borne diseases may also be affected.
Recent trials in carrots have shown a decline in levels of Pythium sulcatum.
Research has shown large differences in sensitivity of soil borne pathogens to
calcium cyanamide, therefore it cannot be considered a soil fumigant.
A soil fumigant is a product that has a broad spectrum, destructive effect on soil life, including pathogens and on germinating seeds, including weeds.

Effect on weeds
The herbicide action of calcium cyanamide acts only in the top 3–4 cm of the soil.
This means it mainly affects newly germinated weed seedlings and small weeds up to the 4-leaf stage.
Weed seeds deeper in the soil, or weeds propagated by rhizomes, are not adequately controlled.

Breakdown of crop residues
Calcium cyanamide can be used to accelerate the breakdown of crop residues because it supplies nitrogen and has a liming effect.
The sanitising effect helps by supressing weeds and diseases.
In Europe, calcium cyanamide is used in the manufacture of compost.

How calcium cyanamide works
A few hours after being applied to the soil, the soil water reacts with calcium cyanamide to form calcium dihydroxide and hydrogen cyanamide (not cyanide).
Hydrogen cyanamide is toxic to plants, and has strong fungicidal properties.
Calcium cyanamide can inhibit the growth and sporulation of pathogenic fungi, and unlike cyanide, it does not form poisonous gases in the presence of moisture.
Hydrogen cyanamide is completely converted to urea in 7–14 days and, to a certain extent, to dicyandiamide, which is a nitrification inhibitor. Urea in the soil is further converted to ammonium, however the dicyandiamide hinders further breakdown of ammonium to nitrate.
The calcium dihydroxide has a liming effect, and this leads to an accumulation of ammonium nitrogen in the soil before the ammonium can be adsorbed by clay minerals, temporarily immobilised by soil microflora or taken up by plants.
In other words, calcium cyanamide is also a slow release form of nitrogen for the crop, and is eventually converted to nitrate.

SYNONYMS:

Alzodef
calcium;cyanamide
156-62-7
Aero cyanamid granular
USAF CY-2
Aero cyanamid special grade
Cyanamid
Nitrolim
Calcium cyanamid
Cyanamid granular
NCI-C02937
CY-L 500
Cyanamid special grade
WLN: CA NCN
NSC7078