Calcium ammonium nitrate manufacturing

This subsection discusses the production of ammonia, urea, ammonium sulfate, ammonium nitrate (AN), calcium ammonium nitrate (CAN), and ammonium sulfate nitrate (ASN). The manufacture of nitric acid used to produce nitrogenous fertilizers typically occurs on site and is therefore included here. 

The resulting AN solution may be handled in various ways103. It can be stored as a solution, used in down-stream plants or sold as a solution it can be formed into solid AN by prilling or granulation, or it can be mixed with a solid filler. The most common filler is calcium carbonate in the form of ground limestone, dolomite or by-product calcium carbonate. This product is known as Calcium Ammonium Nitrate (CAN) and can be prilled or granulated. Granular products that contain AN and either ammonium or calcium sulphate are also manufactured. 

Depending on manufacturing method, NPK fertilizers of identical chemical composition differ in water content, sieve analysis, grain shape, and surface. This accounts for the different amounts required to produce optimal effects. On the basis of results obtained so far, this method is not recommended for conditioning calcium ammonium nitrate. 

The calcium nitrate solution is treated with a calculated quantity of ammonium sulphate to precipitate calcium sulphate and ammonium nitrate is recovered from the resulting solution by evaporation, for use in the manufacture of explosives. 

This is an endothermic reaction of non-explosive character. It is evident from reaction (6a) why ammonium nitrate becomes acid during storage. Owing to the presence of free nitric acid in ammonium nitrate, its admixture with nitroglycerine may cause the latter to decompose in the course of time. Hence a little calcium carbonate, e.g. 0.3%, is very often added to ammonium nitrate destined for the manufacture of explosives including nitroglycerine. 

Most of the nitric acid is utilized in the form of 50 to 70% acid for the manufacture of nitrogen-containing fertilizer, particularly ammonium nitrate. Ammonium nitrate is also used as an explosive e.g. in mining, due to its low explosion temperature (safety explosive). Other industrially important nitrates are sodium nitrate, a speciality fertilizer and oxidizing agent in the glass and enamel industries, and calcium and potassium nitrates, which are also used as fertilizers. Nitric acid is also utilized in the digestion of raw phosphate (Odda process, which is not operated in the USA, see Section 2.1.2.4) ... 

For the manufacture of ammonium nitrate from calcium nitrate see Section 2.1.2.4). 

In analogy with the manufacture of potassium sulfate, potassium nitrate can also be manufactured by metathesis with other nitrates, e.g. with sodium, calcium or ammonium nitrate, as follows ... 

Regarding the manufacture of ammonium nitrate from calcium nitrate the reader should consult the parents —Dyes, English Patent, 15,391, 1908 Nydegger and Wedekend, English Patent, 20,907, 1909. 

The growth medium includes defined salts, complex nutrients, surfactants, and inducer. The salts are the typical fermentation salts, including potassium phosphate, ammonium nitrate, ammonium sulfate, calcium chloride, and magnesium sulfate [33]. The complex nutrients are most often 5 to 25 g L of corn steep liquor but can also include yeast extract. The surfactants are added to control or suppress foam formation. The surfactants used include commercial antifoams as well as soybean oil or palm oil. The inducers are proprietary to each manufacturer but will contain an inexpensive mixture of soluble and/or insoluble sugars. Some inducers used include milk whey, which contains lactose Solka floe cellulose or, sugar or paper mill waste streams. 

A suspected water gel is examined on a microscope slide to identify the microspheres used in slurry and emulsion explosives. The gel is directly extracted with methanol, which dissolves the amine salt, and a small amount of NH4NO3. TLC on a cellulose plate using a chloroform-methanol-water system separates the sensitizers. The plate is sprayed with ni-nhydrin and heated to visualize the amine salt. A second spray with diphenylamine in ethanol followed by long-wave UV irradiation visualizes the NFi4N03 if desired. Alternatively, the methanol extract may be evaporated to near dryness, redissolved in water, and analyzed by IC to identify the sensitizer. An intact sample can also be extracted with water using either a small homogenizer or ultrasonic agitation to disrupt the gel structure. Microspheres float on the surface and are removed for examination by SEM-EDX to characterize the manufacturer. Spot tests and IC identify ammonium, calcium, and nitrate ions in the water extract. Flake aluminum, if present, is identified as described above. 

Another major manufacturer was the Eastern Dynamite Corporation, at Wilmington, Delaware, which developed the patents of Holmes [26]. The starch was nitrated by means of mixed nitric-sulphuric acid and then stabilized by prolonged boiling with water in the presence of calcium carbonate, for 75-100 hr. In later patents the addition of ammonium salts to the water was recommended. 

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