P Fertilizer Production and Technology.

Phosphorus (P) fertilizer input is critical for the production of an adequate food supply for a rapidly increasing world population.  This presentation- an abbreviated version of a new IPNI presentation on the P fertilizer industry- will cover the major considerations in phosphate fertilizer production and technology.  Early sources of P used in agricultural production were primarily organic materials.  Among the most important of these sources were bones and guano (seabird droppings).  By the beginning of the nineteenth century the value of calcium phosphates in bones was recognized, and the acidulation of bones to improve the solubility of phosphates began sometime in the early to mid 1800s.  This was the beginning of the superphosphate industry.  Superphosphate production eventually became based on phosphate rock (PR), as discovery and development of PR deposits advanced.  The majority of P fertilizer used today is the result of the acidification of PR.  Phosphate rock deposits occur in several countries.  According to the latest USGS estimates, Morocco has the largest deposits, followed by China, Jordan, South Africa, and the USA.  Phosphate rock must be beneficiated to remove impurities before reacting with acid.  Once impurities are removed PR is reacted with acid (e.g., sulfuric or nitric acid) to produce phosphoric acid.  This “wet process” phosphoric acid is the foundation of the modern P fertilizer industry.  Several major P fertilizer sources including ammoniated orthophosphate and polyphosphate fertilizers are produced from wet process phosphoric acid.