Superphosphate fertilizers

Resources of Sulfur. In most of the technologies employed to convert phosphate rock to phosphate fertilizer, sulfur, in the form of sulfuric acid, is vital. Treatment of rock with sulfuric acid is the procedure for producing ordinary superphosphate fertilizer, and treatment of rock using a higher proportion of sulfuric acid is the first step in the production of phosphoric acid, a production intermediate for most other phosphate fertilizers. Over 1.8 tons of sulfur is consumed by the world fertilizer industry for each ton of fertilizer phosphoms produced, ie, 0.8 t of sulfur for each ton of total 13.7 X 10 t of sulfur consumed in the United States for all purposes in 1991, 60% was for the production of phosphate fertilizers (109). Worldwide the percentage was probably even higher. 

J. Murray patented his production of " superphosphate fertilizer (a name coined by him for the product of HiSOu on phosphate rock). 

Transparent polyethylene can be also applied to the protection of window glass against aggressive media, e.g., the effect of hydrogen fluoride on the plants producing superphosphate fertilizers. The use of transparent polyethylene film for window glass makes it possible to cut down on the heat losses due to the lower thermal conductance of polyethylene as compared to glass. 

The transfer of trace elements in phosphate rocks to P fertilizers is dependent upon the manufacturing processes. Triple superphosphate fertilizer contains 60-70% of the Cd present in phosphate rocks (Wakefield, 1980). The transfer coefficients may be similar for most other elements and heavy metals even though there are little data on the transfer of other elements from phosphate rocks to P fertilizers. In general, based on some long-term (> 50 years) soil fertility experiments in the U.S., annual Cd rates from the application of phosphate fertilizers are estimated to range from 0.3 to 1.2 g per ha. The addition of Cd to soils as a contaminant from P fertilizers... 

Reaction with calcium triphosphate fluoride yields calcium dihydrogen phosphate, a component of superphosphate fertilizer ... 

Sulfuric acid is universally used in the chemical industry in the production of numerous products. Its largest use, accounting for approximately two-thirds of its total use, is in the production of fertilizer. Adding acid to phosphate rock produces phosphate fertilizer. Superphosphate fertilizer is produced by adding sulfuric acid to the phosphate rock fluorapate, [Ca3(P04)2]3CaF2, according to the reaction ... 

H3P04) and calcium sulfate (CaS04 2H20, also known as gypsum). The phosphoric acid is then processed with the phosphate rock to produce triple superphosphate fertilizer. Triple superphosphate has three times the concentration of phosphorus as superphosphate. Another fertilizer produced from sulfuric acid is ammonium sulfate, (NH4)2S04. Ammonium sulfate is produced by reacting ammonia and sulfuric acid. 

Fluorine Probably essential element used as CaFj by some mob hisks. Moderately toxic, msy cause mottled teeth. Pollution by fluoride present in superphosphate fertilizers. Ca. 1 ppm In water provides cariostatic action, beneficial in the treatment of Osteoporosis. 

Fluorides do nol usually ntnve from the soil lo plants and on to livestock feedstuff s and human foodstuffs ill amounts that are toxic. Injury tu plants from fluoride in the soil has been noted on soils that are loo acid for the satisfactory growth of most plants. On limed soils or soils w ith sufficient calcium for optimum growth, any fluorine added lo the soil reacts with the calcium and other soil constituents to form insoluble compounds, which are not taken up by the plants. Rock phosphate and some kinds of superphosphate fertilizers contain large amounts of calcium fluoride, bul the fluorine content of the plants grown on soils that have been heavily fertilized with these phosphates is nut appreciably increased. Tea and some other members of the Theaeeae family are the only plants that take up very-much fluorine from the soil. 

Minerals of economic importance within sedimentary formations include, hut are not limited to fluorite, barite, phosphorite, and oolitic hematite. Fluorite is utili/ed us a flux in steelniakiitg and when of high quality as lenses and prisms in the optical industry. Barite is an essential mineral used m gas- and oil-well drilling. Phosphorite, a product of chemical precipitation from seawater, when ircaled with sulfuric acid, produces superphosphate fertilizer, (.killtic hematite deposits of extensive size are important sources of iron ore. 

A significant concern in all nitration plants using mixed acid centers on the disposal method or use for the waste acids. They arc sometimes employed for production of superphosphate fertilizers. Processes have also been developed to reconcentrate and recycle the acid. 

The resulting mixture of calcium dihydrogen phosphate and calcium sulfate is sold as superphosphate fertilizer. It is of interest to note that the production of calcium sulfate is avoided by using phosphoric acid rather than sulfuric ... 

Although superphosphate fertilizer provides available phosphorus, it is advantageous to provide other needed elements such as nitrogen and potassium at the same time. Thus, diammonium hydrogen phosphate [(NH4)2HP04] provides both nitrogen and phosphorus, while potassium ammonium phosphate [K(NH4)HP04] makes available the three elements most needed in the maintenance of soil fertility. 

Poorly crystalline or amorphous Phosphorite sediments made from the hard remains of marine organisms are the principal commercial source of phosphates, although Apatites are also mined. Treatment of phosphate minerals with sulfuric acid yields superphosphate fertilizer, a mixture of Ca(H2P04)2, H3PO4 and CaS04. Phosphoric acid treatment gives triple superphosphate , rich in Ca(H2P04)2. Other soluble fertilizers such as ammonium phosphates are obtained from these products. 

Although two Swedish chemists. Carle Scheele and Johann Galen, had shown in 1769 that calcium phosphate was the principal constituent of bones, the first commercial superphosphate fertilizer did not appear until 1843. John Bennet Lawes (1814—1900), an Oxford graduate, is credited with developing the process that consists of treating phosphate rock (PR)... 

Use Direct application to soil as fertilizer, neutralizing superphosphate fertilizers. 

Phosphate salts, applied to soils as fertilizers, may acidify over the long term. For example, superphosphate fertilizers contain Ca(H2P04)2, which dissolves readily in water ... 

Calcium dihydrogen phosphate, which is used in the production of triple superphosphate fertilizers, can be formed from the reaction of apatite, Ca5(P04)3F, with phosphoric acid. How many grams of calcium dihydrogen phosphate can be formed from 6.78 g of Ca5(P04)3F ... 

Sulfur, mainly in the form of sulfuric acid, is an enormously important industrial chemical. The amount of sulfuric acid consumed by a given nation is an indicator of that country s industrial development. Figure 15.3 illustrates applications of sulfur and sulfuric acid (see also Box 10.3). Sulfur is usually present in the form of an industrial reagent (e.g. in H2SO4 in the production of superphosphate fertilizers described in Section 14.2), and it is not necessarily present in the end product. 

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