Purification of Wet Process Phosphoric Acid by a Solvent Extraction Process

Solvent extraction for purification of wet process phosphoric acid (WPPA) has been commercially practiced in Europe and several other countries for more than two decades. But the first commercial solvent extraction WPPA purification plant did not begin operating in the U.S. until the late 1980s. This plant, with a capacity of 108,860 t/yr of P₂O₅ equivalent purified acid, is located in Aurora, NC, and is a joint venture of Albright & Wilson (A&W), Olin, and Texasgulf Corporations. The plant employs A&W's proprietary technology that uses methyl isobutyl ketone (MIBK) as a solvent. Shortly thereafter, a second solvent extraction WPPA purification plant in the United States was completed by Rhone-Poulenc Basic Chemicals in Geismar, LA, which uses Rhone-Poulenc's own technology.

SRI's cost estimates show that the A&W solvent extraction technology for high purity phosphoric acid production has substantial cost advantage over the costs of producing high purity acid via the electric furnace thermal acid process.