Fertilizer granular

Coated Fertilizer - Granular fertilizer that is covered with a thin layer of a different material in order to improve the behawor and/or modify the characteristics of the fertilizer (ISO). 

Although the deliberate productfon of ammonium chloride for fertilizer use is rare in regions other than east Asia, it is a very common constituent of compound fertilizers (granular or liquid) in Europe and North America. It is formed in NPK fertilizers by reaction of ammonium nitrate and/or ammonium sulfate with potassium chloride ... 

Figure 15.2. Comparison of Sizes of Fertilizer Granular Material With "Coarse and Granular Potash.

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. 

Fig. 2. Fertilizers in the prilled or granular form (a), prilled ammonium nitrate (b), prilled urea (c), granular urea (d), granular diammonium phosphate ...

Essentially all the ammonium sulfate fertilizer used in the United States is by-product material. By-product from the acid scmbbing of coke oven gas is one source. A larger source is as by-product ammonium sulfate solution from the production of caprolactam (qv) and acrylonitrile, (qv) which are synthetic fiber intermediates. A third but lesser source is from the ammoniation of spent sulfuric acid from other processes. In the recovery of by-product crystals from each of these sources, the crystallization usually is carried out in steam-heated sa turator—crystallizers. Characteristically, crystallizer product is of a particle size about 90% finer than 16 mesh (ca 1 mm dia), which is too small for satisfactory dry blending with granular fertilizer materials. Crystals of this size are suitable, however, as a feed material to mixed fertilizer granulation plants, and this is the main fertilizer outlet for by-product ammonium sulfate. 

The routes by which mineral phosphates are processed into finished fertilizers are outlined in Eigure 7. World and U.S. trends in the types of products produced are shown in Eigures 8 and 9, respectively. Most notable in both instances is the large, steady increase in the importance of monoammonium and diammonium phosphates as finished phosphate fertilizers at the expense of ordinary superphosphate, and to some extent at the expense of triple superphosphate. In the United States, about 65% of the total phosphate appHed is now in the form of granular ammonium phosphates, and additional amounts of ammonium phosphates are appHed as integral parts of granulated mixtures and fluid fertilizers. 

Granular TSP (—6 + 16 mesh (1.19 to 3.35 mm dia)) is preferred for direct appHcation and is used in bulk blend fertilizers. A widely used slurry granulation process, the Dorr-OHver process, is illustrated in Figure 11. The ground rock is mixed with 38—49% P2 5 series of reaction vessels. 

Table 8. Specifications of Fertilizer-Grade Granular Diammonium Phosphate ...

When 20% of the phosphoms was polyphosphate, the compounds ia the product were ia the ratio of 3.5 mole MAP per mole of the pyrophosphate. The principal use of the material was ia the production of suspension fertilizers. In this appHcation the polyphosphate content imparted improved storage properties to the suspensions. The granular soHd APP, however, also had excellent storage properties and was a good material for use ia bulk blends and for direct appHcation. 

Fig. 16. Steam granulation process for production of granular mixed fertilizers from dry, pulverized feed materials (7). A granulator producing 12 t/h would...

Fig. 18. TVA-type cogranulation process with preneutralizer, as used for production of granular mixed fertilizers. Feed materials such as ammonium sulfate, ammonium nitrate, urea, superphosphates, sulfuric acid, and potash are used.

Compaction—Alternative Approach for Granular Eertili yers, lEDC Technical Bulletin T-25, International Fertilizer Development Center, Muscle Shoals, Ala., 1983. 

Granulation processes offer a number of important advantages. The most significant are decreased pollution problems and the abiUty to produce granules of almost any reasonable size allowing close size matching with granular ammonium phosphates and potassium chloride in the preparation of NPK fertilizers (26). 

Products are granular, free-flowing, and dust-free by nature, since no flow conditioner dust is used as with sulfur-coated fertilizers. They possess excellent abrasion resistance and handling integrity. Since the outer coating is a hard polymer, the products do not leave waxy residues on material handling and apphcation equipment. 

Phosphate Fertilizer Industry Granular Triple Superphosphate Storage Facilities Goal Preparation Plants Ferroalloy Production Facilities Steel Plants Electric Arc Furnaces Constructed after October 21, 1974, and on or before August 17,1983... 

The mono salt tends to produce needles while the di-basic salt results in crystals that are more granular. Ammonium phosphate finds application as a fertilizer. 

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