Ammonium phosphates storage

Orthophosphate Hquid mixtures are ineffective as micronuttient carriers because of the formation of metal ammonium phosphates such as ZnNH PO. However, micronutrients are much more soluble in ammonium phosphate solutions in which a substantial proportion of the phosphoms is polyphosphate. The greater solubiHty results from the sequestering action of the polyphosphate. The amounts of Zn, Mn, Cu, and Fe soluble in base solution with 70% of its P as polyphosphate are 10 to 60 times their solubiHties in ammonium orthophosphate solution. When a mixture of several micronutrients is added to the same solution, the solubiHty of the individual metals is lowered significantly. In such mixtures the total micronuttient content should not exceed 3% and the storage time before precipitates appear may be much shorter than when only one micronuttient is present. 

It is unusual for the suspended matter to separate completely in the storage tank and some form of filtration will be desirable. The filtrate will contain the soluble organic matter which can be converted into carbon dioxide, water and nitrates by the action of micro-organisms. To sustain the life of the micro-organisms the presence of nitrogen and phosphorous is necessary and many effluents are deficient in these elements, making the addition of some ammonium phosphate necessary. 

The settled slurry containing about 17 to 20% solids is then heated to 90° C. to convert the magnesium ammonium phosphate hexahydrate to the monohydrate. After dehydration, the slurry is filtered. The filter cake is washed, mixed with recycled fines, and granulated. The granules are dried, screened, and then conveyed to product storage. It is necessary to wash the filter cake only if the chloride content of the dried product must be less than 1%—for the few crops that are sensitive to chloride, such as tobacco. 

As described previously, phosphate rock dust, fluorides, acids, ammonia, and radioactive elements are the main health hazards in fertilizer production. Fertilizer products are of low hazard however, ammonium nitrate storage areas must be kept free of organic materials, Coating materials such as crystalline silica are hazardous if inhaled. 

Ammonium phosphate fertilisers have assumed a greatly increased importance in recent years and have now become the leading commercial product. Mixtures of the mono- and di-salt are obtained from direct reaction of ammonia with wet process phosphoric acid. Commercial production by this method started in the United States in 1917, and about half of the current world production of phosphoric acid is converted to ammonium salts. The tri-ammonium salt is not favoured in fertilisers because of the loss of ammonia on storage. 

The popularity of ammonium phosphate fertilisers arises from their high nutrient content of both P and N, high solubility and good storage and handling characteristics. They are easy to produce and compete economically with the longer-established calcium salts. Commercial products are available as solutions, solids or suspensions. 

A diesel fuel stabilizer containing a blend of amines, polyamines, and alkyl ammonium alkyl phosphate as specified under MIL-S-53021 is recommended for federal diesel fuel oil. This stabilizer is to be used at a treat rate of 25 lb/1,000 barrels. It is not intended for use in routine applications, but for situations where increased stability protection is required. Typical applications include fueled equipment undergoing long-term storage in a warehouse or depot, prepositioned equipment or equipment maintained in a high-temperature environment. 

It is also used for the manufacture of soluble phosphate fertilizers (Chap. 21), of ammonium sulfate for use as a fertilizer, of other sulfates, and in the manufacture of many chemicals and drugs. Steel is usually cleaned of iron rust (is pickled ) by immersion in a bath of sulfuric acid before it is coated with zinc, tin, or enamel. The use of sulfuric acid as the electrolyte in ordinary storage cells has been mentioned (Chap. 14). 

Analyzing compounds that are sensitive to microbial action (phosphate, ammonium, nitrate, nitrite, silica) should always be completed approximately within one day, if the samples were not preserved by the addition of TTE (trifluorotrichloroethane). Even in its preserved state, it is not recommended to store the sample for longer than four weeks. Storage is best in the dark at about 4°C freezing the samples is not recommended. 

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