Phosphoric acid world production

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. 

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. 

In recent years, concentrated phosphoric acids, which may contain as much as 70% to 75% P2O5 content, have become of great importance to agriculture and farm production. World-wide demand for fertilizers has caused record phosphate production. Phosphates are used in the production of special glasses, such as those used for sodium lamps. 

The ores of most importance are fluorspar, CaF2 fluorapatite, Ca (P0 2Fj cryoHte [15096-52-3], Na AlF. Fluorspar is the primary commercial source of fluoiine. Twenty-six percent of the world s high quaHty deposits of fluorspar are ia North America. Most of that is ia Mexico. United States production ia 1987—1991 was 314,500 metric tons, most of which occurred ia the Illinois-Kentucky area. Imported fluorspar ia 1990—1991 represented about 82% of U.S. consumption 31% of U.S. fluorspar imports were from Mexico and 29% from China compared to 66% from Mexico ia the 1973—1978 period. The majority of the fluorine ia the earth s cmst is ia phosphate rock ia the form of fluorapatite which has an average fluorine concentration of 3.5%. Recovery of these fluorine values as by-product fluorosiHcic acid from phosphate production has grown steadily, partially because of environmental requirements (see Phosphoric acid and THE phosphates). 

The estimated world production of wet-process phosphoric acid was 24,001,000 metric tons of P20 in 1993. Capacity was 34,710,000 metric tons. Over 90% of phosphoric acid production is wet-process (agricultural-grade) acid the remainder is industrial-grades (technical, food, pharmaceutical, etc) made by the thermal route or by the purification of wet-process acid. Table 11 fists U.S. production of wet-process and industrial-grade acids. 

Chemists are not the only ones who make use of acid-base chemistry. In fact, most of the chemical manufacturing that goes on in the world is related to the production of four simple, but very useful, products—sulfuric acid, phosphoric acid, sodium hydroxide, and sodium chloride. 

Chlorination products of glyphosate, one of the most widely used herbicide in the world, and glycine, one of the intermediates in glyphosate chlorination, were investigated by Mehrsheikh et al. [111]. Both compounds followed a similar degradation route, with the final glyphosate chlorination products identified as methanediol and other small molecules, such as phosphoric acid, nitrate, CO2, and N2. 

Lewis and protic acids, usually AICI3 and H2SO4, are used in the liquid phase at temperatures of 40-70°C and at pressures of 5-15 atm. Phosphoric acid on kieselguhr promoted with BF3 (UOP process)309 319 is used in gas-phase alkylation (175-225°C, 30-40 atm). In addition to the large excess of benzene, propane as diluent is also used to ensure high (better than 94%) propylene conversion. This solid phosphoric acid technology accounts for 80-90% of the world s cumene production. 

The principal dihydrate processes in use as of 2000 are shown in Table 23.6. During the decade 1990-2000, many of the smaller plants and even some larger than 450 tons per day P205 plants have been shut down due to environmental or market conditions. This has resulted in more production in Morocco, Jordan, and India, and less in Europe. Most of the world s phosphoric acid is produced by the dihydrate method, but there is likely to be... 

Evaporation. Phosphoric acid is used for downstream products mostly at 28 percent P205, 40 percent P205, and 54 percent P205. Many plants also make clarified merchant grade acid (MGA), which, at 52-54 percent P205, is a world traded product. 

Available production figures for many of the large world producers of phosphoric acid are given in Table 10.8. This product does show a more generally increasing trend with time, since fertilizer demands on phosphoric acid output have generally climbed. 

More than 90 percent of commercial phosphorus production is in the form of calcium salts of phosphoric acid, H3PO4, used as fertilizers. Other significant uses of phosphorus compounds are in the manufacture of matches (phosphorus sulfides), food products and beverages (purified phosphoric acid and its salts), detergents (sodium polyphosphates), plasticizers for polymers (esters of phosphoric acid), and pesticides (derivatives of phosphoric acid). Related to the phosphorus pesticides are nerve gases, poisonons com-potmds that rapidly attack the central nervous system, initially developed during World War II. see also Deoxyribonucleic Acid (DNA) Fertilizer Pesticides. 

World phosphoric acid production has stabilized in the past few years with, however,- a slight decrease from 35.5 million tonnes P20s in 1990 to 33.6 million tonnes P2O5 in 1993. According to projections by the... 

Reaction System - There are so many types of reaction systems in use throughout the world that no attempt will be made to identify all of them, The objective in designing the reaction system is to carry out the reaction between phosphate rock and sulfuric acid so as to recover a maximum percentage of the P2O5 from the rock as product phosphoric acid in the simplest and least expensive manner. Since the filtration step is the most critical and expensive step in the process, a primary objective in the reaction step is to form gypsum crystals of such size and shape that the filtration and washing can be carried out rapidly and efficiently. 

The production of fertilizers derived from phosphoric acid has increased significantly in the last 50 years because, among other things, these are high-analysis products, thanks to the removal of calcium as byproduct calcium sulfate in phosphoric acid production. Moreover, technical breakthroughs in the field of phosphoric acid and ammonium phosphate manufacture, plus economies of scale, have resulted in high capacity world size" plants, which produce a limited range of products at very competitive prices. 

The diethyl derivative also serves as an insecticide total world production of these phosphoric acid esters is estimated to be around 20,000 tpa. 

About 90% of world phosphoric acid production is currently by the wet process . The success of the wet over the thermal process has been largely governed by the relative cheapness of sulphuric acid compared to that of electric power. However, viscosity and filtration problems arise in the wet process when too high a level of impurities is present, whereas the thermal process (Chapter 4.1) will cope with lower grades of ore. 

Mono- and dicalcium phosphates are added to farm animal foodstuffs to guard against dietary deficiency of P. Stock feed dicalcium phosphate, CaHP04 2H2O, can be made from calcium hydroxide and most wet process phosphoric acid. Apart from possible reduction of P absorption, the Fe, Al and Mg salt impurities do not seem to be harmful to animals. The current world usage of calcium phosphates in animal foodstuffs exceeds 4 x 10 tons per annum. Over 95% of this usage (generally at 1 2% addition in proprietary products not farm produced) is almost equally divided between cattle, pig and ponltry foods. 

Crystalline trisodium phosphate has a variable formula, (Na3P04- 12H20) Na0H, in which x ranges between 4 and 7. It is crystallized below 60°C from an aqueous solution of phosphoric acid that has been neutralized with a slight excess of sodium hydroxide. The crystals are isolated by centrifugation and dried at 40°C to minimize dehydration. World production of phosphoric acid in 1993 was 33 million tons, of which over 90% is used in agriculture. ... 

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