Phosphate fertilizers production

Nitric Phosphate. About 15% of worldwide phosphate fertilizer production is by processes that are based on solubilization of phosphate rock with nitric acid iastead of sulfuric or phosphoric acids (64). These processes, known collectively as nitric phosphate or nitrophosphate processes are important, mainly because of the iadependence from sulfur as a raw material and because of the freedom from the environmental problem of gypsum disposal that accompanies phosphoric acid-based processes. These two characteristics are expected to promote eventual iacrease ia the use of nitric phosphate processes, as sulfur resources diminish and/or environmental restrictions are tightened. 

Although tetrafluorosilane can be readily produced by the action of hydrogen fluoride on sihca, its production is a by-product of HF production by the reaction of fluorospar and sulfuric acid and as a by-product from phosphate fertilizer production by the treatment of fluoroapatite with sulfuric acid (171). The most significant U.S. production is by IMC-Agrico at Uncle Sam, Louisiana. 

The wodd s largest sulfur iaveatories are stiH ia Canada. By the end of 1994, after significant vattiag, stocks iacreased by approximately 2.2 x 10 to 7.8 X 10 t. The United States, which had 4.2 million metric tons of sulfur inventories in 1982, reduced sulfur inventories to the lowest levels in a decade during 1992, a record year for phosphate fertilizer exports. This changed during 1993—1994, when phosphate fertilizer production eased and sulfur stocks increased to 1.1 million metric tons. Sulfur inventories in Poland and West Asia have also declined slightly (33). 

Because sulfuric acid has its greatest use in fertilizers, trends in that industry have a significant effect on the sulfuric acid business. Owing to a weak U.S. doUar in the early 1990s and high demand for fertilizer abroad, a considerable portion of U.S. phosphate fertilizer production was exported. High fertilizer exports are expected to continue until Thkd World countries can meet thek own demands. 

The oxoacids and oxoanions of phosphorus are among the most heavily manufactured chemicals. Phosphate fertilizer production consumes two-thirds of all the sulfuric acid produced in the United States. 

SARE, The sustainable agriculture research and education program. Website http //www.sare.org SAREP, University of California Sustainable Agriculture Research and Education Program (1997) What is sustainable agriculture Available at website http //www.sarep.ucdavis.edu/concept.htm Schultz JJ (1992) An examination of the environmental issues facing the phosphate fertilizer production sector - indicated cost of environmental compliance. In Schultz JJ (ed) Phosphate fertilizers and the environment... 

National Emission Standards for Hazardous Air Pollutants From Phosphate Fertilizers Production... 

Table 2.1-3. Phosphate Fertilizer Production in F.R. Germany in Period 1989 to 1992 in lO t/aPjOj.

KEY WORDS gypsum, phosphoric acid, radium, bypnxiuct gypsum, phosphogypsum, hazardous waste, phosphate fertilizer production... 

Stayner L, Meinhardt T, Lemen R, et al. 1985. A retrospective cohort mortality study of a phosphate fertilizer production facility. Arch Environ Health 40 133-138. 

Phosphate rock is only one of the materials needed in the production of phosphate fertilizers. Although the availability of low-cost phosphate rock is certainly advantageous in any phosphate fertilizer production situation, the total costs of providing other needed chemicals (sulfur, sulfuric acid, etc.) and power (electrical, fuels) may more than overshadow the advantage of a low-cost phosphate rock source in a developing country. When all the development costs and production costs are tabulated, the low cost of labor in a developing country may be a minor factor. 

Sulfuric acid is an important raw material for phosphate fertilizer production and to a much lesser extent for nitrogen and potassium fertilizers. World production of sulfuric acid was about 158 million tonnes of H2SO4 in 1991 [11, from which 58% was used in fertilizer production. 

In the last three decades, phosphoric acid has become the most significant source of phosphate fertilizer production, and this trend is expected to continue worldwide in the foreseeable future, Growth is particularly expected in southeast Asian countries, which are implementing national programs to become self-supporting in the production of fertilizers. 

U.S. consumption of sulfur is about 12 million t/yr. For a relative comparison, a 1,000 MW IGCC power plant would produce about 70,000 t/yr sulfur (assuming a 3 weight percent (wt%) sulfur feed coal, 65% annual capacity factor, and 99% sulfur recovery). About 80% of this sulfur is converted to sulfuric acid in the production of phosphate fertilizer. Fertilizer demands for sulfur are expected to increase with time as world food demand increases. U.S. phosphate fertilizer production centers in Florida, which has large supplies of phosphate rock. 

The first American superphosphate plant opened in 1850 by William Davison and T.S. Chapell of Baltimore. Other early producers in this decade were Potts Klett and Moro Phillips of Philadelphia. The introduction of the phosphate fertilizer industry created the first significant sulfuric acid market in the U.S. This country would eventually dominate phosphate fertilizer production, thanks mainly to massive phosphate deposits in Florida, which were first mined in 1888. Now, in the early 21 century, the U.S. market for sulfuric acid in the phosphate fertilizer industry is over 25 million tonnes, representing over 8.0 million tonnes per year of sulfur. The largest producer of phosphate fertilizer in the world is Mosaic, formed from the merger of IMC Global and Cargill Crop Nutrition in October 2004 (see Table 2.5). 

Ammonia in Multi-nutrient Fertilizers, The ammonia-based fertilizers discussed thus far all contain only one of the three major plant nutrients, namely, nitrogen. Referring again to Fig. 11.2, one may see that ammonia is the source of fertilizer nitrogen also, either directly or via nitrogen solids or solutions, in multinutrient fertilizers. These are fertilizers that contain two or three of the major plant nutrients-nitrogen, phosphorus, and potassium. Ammonium phosphates, both mono-and di-, are phosphate fertilizer products that also carry nitrogen. (These will be discussed... 

States during the 1980s are given in Table 14.5 for major acid-producing states. The South accounts for about 75 percent of new sulfuric acid production, most of which is captive consumption for phosphate fertilizer production. With its massive phosphate rock deposits, Florida leads the nation in sulfuric acid production, to feed its phosphoric acid plants. Sulfur mines and recovered sulfur from oil and gas operations in Texas and Louisiana provide brimstone feed to sulfuric acid plants. Many of these plants are sited near major waterways to provide cheap transportation for raw materials and fertilizer products. Southwestern sulfuric acid plants usually are associated with smelters that ship the acid by rail to fertilizer plants. 

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