Ammonium nitrate-urea

The urea produced is normally either prilled or granulated. In some countries there is a market for Hquid urea—ammonium nitrate solutions (32% N). In this case, a partial-recycle stripping process is the best and cheapest system. The unconverted NH coming from the stripped urea solution and the reactor off-gas is neutralized with nitric acid. The ammonium nitrate solution formed and the urea solution from the stripper bottom are mixed, resulting in a 32—35 wt % solution. This system drastically reduces investment costs as evaporation, finishing (priQ or granulation), and wastewater treatment are not required. 

Urea processes provide an aqueous solution containing 70—87% urea. This solution can be used directiy for nitrogen-fertilizer suspensions or solutions such as urea—ammonium nitrate solution, which has grown ia popularity recentiy (18). Urea solution can be concentrated by evaporation or crystallization for the preparation of granular compound fertilizers and other products. Concentrated urea is sohdified ia essentially pure form as prills, granules, flakes, or crystals. SoHd urea can be shipped, stored, distributed, and used mote economically than ia solution. Furthermore, ia the soHd form, urea is more stable and biuret formation less likely. 

Table 4. Properties of Urea Ammonium Nitrate Nonpressure Solutions...

Several zinc and copper micronuttient compounds are soluble in a variety of nitrogen solutions. Ammonia—ammonium nitrate solutions containing 2.5% Zn and 1% Cu can be prepared (100). Micronutrients are not very soluble in urea—ammonium nitrate solution unless the pH is raised to 7 or 8 by adding ammonia, whereupon zinc and copper become much more soluble. 

Markets. Industrial use of ammonia varies according to region. Eor example, industrial usage represents 20% of the ammonia production in the United States and Western Europe, 10% in the USSR, 1—10% in Asia, and 5% in Latin America and North Africa (79). Fertiliser ammonia consumed domestically in most countries is converted to straight or compound fertilisers such as urea, ammonium nitrate, diammonium phosphate, and various grades of mixed fertilisers. However, almost 29% of ammonia nitrogen in the United States is consumed as direct appHcation material. The use of nitrogen solution such as urea and ammonium nitrate (UAN) has also become popular in the United States and the USSR. 

Nitrogen solutions consist of fertilizer product combinations, eg, ammonium nitrate —ammonia, urea—ammonium nitrate—ammonia, urea—ammonium nitrate, and urea—ammonia solutions. Mixed fertilizers cover a broad range and can be loosely defined as fertilizers which contain chemically mixed nitrogen, phosphoms, and potassium (N—P—K). Examples are ammonium phosphate—potash mixtures and ammonium phosphate nitrates. 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

Prilling Pressure compaction 0.7 to 2 Moderate High to very high vary widely Very narrow size Urea, ammonium nitrate pharmaceuticals, catalysts. 

Synthesis gas is a major source of hydrogen, which is used for producing ammonia. Ammonia is the host of many chemicals such as urea, ammonium nitrate, and hydrazine. Carbon dioxide, a by-product from synthesis gas, reacts with ammonia to produce urea. 

The major end use of ammonia is the fertilizer field for the production of urea, ammonium nitrate and ammonium phosphate, and sulfate. Anhydrous ammonia could be directly applied to the soil as a fertilizer. Urea is gaining wide acceptance as a slow-acting fertilizer. 

Table 4.1 gives the use profile for ammonia. It can be applied directly for fertilizer or made into other nitrogen-containing compounds used for fertilizer such as urea, ammonium nitrate, ammonium phosphate, ammonium sulfate, and nitric acid. Overall approximately 80% of ammonia has an end use as fertilizer. Explosives, a second important end use, made from ammonia are ammonium nitrate and, via nitric acid, the nitroglycerin used in dynamite. Chemical intermediates include acrylonitrile and caprolactam, which eventually go into fibers. 

Oxamide, This diamide is sparingly soluble in water and insoluble 111 various organic solvents. It melts at about 350°C, with accompanying decomposition. Because of the low solubility in water, the compound is granulated and used as a slow-release nitrogen fertilizer. Conventional nitrogen ferdlizers such as ammonium sulfate, urea, ammonium nitrate, and ammonium phosphate, are soluble in water, and thus are easily lost as... 

Unusual flux precursors like urea, ammonium nitrate, boric acid, or ammonium boron-hydride have also been studied [173], In all these cases derivatives of amino borate form the liquid phase. 

Urea is used as a solid fertilizer, a liquid fertilizer and miscellaneous applications such as animal feed, urea, formaldehyde resins, melamine, and adhesives. Presently, the most popular nitrogen fertilizer is a urea-ammonium nitrate solution. Urea-formaldehyde resins have large use as a plywood adhesive. Melamine-formaldehyde resins are used as dinnerware and for extra-hard surfaces (Formica ). The melamine is synthesized by condensation of urea molecules. 

Year Ammonia Urea Ammonium Nitrate Ammonium Phosphates (as P2O5)... 

Production of fertilizer grade AN is concentrated mainly in Europe and North America. Apparent demand in the United States was 18% below the 1998 level of 10 billion tons. This was mainly due to weakness in the fertilizer sector. US production of urea-ammonium nitrate (UAN) solutions also dropped significantly (from 3.8 million tons in 1998 to 2.9 million tons in 2001) from 1999 to 2001. In 2001 US ammonium nitrate capacity remains well in excess of domestic requirements as the industry operated at less than 70% of nameplate US capacity. Table 10.1 summarizes US supply and demand240. 

One of the most important uses of hydrogen today is for the fixation of atmospheric nitrogen into the form of ammonia. Ammonia then carries, either directly or in combination with other compounds, such as urea, ammonium nitrate and various NPK materials, the supplemental nitrogen nutrient to the soil for plant growth. 

Trade is an important component of the world nitrogen industry, and trade in each of the nitrogen products analyzed (ammonia, urea, ammonium nitrate, ammonium sulfate, and ammonium phosphates) increased substantially between 1986 and 1998. The percentage of production that is traded internationally varies from 10 percent for ammonia up to 40 percent for ammonium phosphates.35... 

Mention was made earlier of the significant quantity of nitrogen applied to farmlands in the form of urea-ammonium nitrate solution and aqua ammonia. Since the late 1950s, there has also been a growing practice of applying mixed fertilizers (NP and NPK) in fluid form. In fact, the growth of the fluids market paralleled bulk-blended products. In 2002/03 about 25 million mt of fluids was produced and corresponded to 7 percent of the world production. North America, and Europe are major markets for fluids. Fluids are also used in high-value crops in some countries of the Middle East and Latin America. 

Urea-ammonium nitrate solution (28-32% N) Solution grade KCI... 

Urea-ammonium nitrate solutions -Urea prills -... 

The consumption of ureaform in the United States is approximately 75,000 tons/year, not including that formed in compound fertilizers from solutions. Most of the production goes into compound fertilizer for specialty uses, such as for lawns, flower gardens, and golf courses. The wholesale price of ureaform per unit of nitrogen is about three times that of urea, ammonium nitrate, or ammonium sulfate. 

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