Phosphoric acid is used widely in phosphate agricultural fertilizers. Due to its non-toxic and mildly acidic nature, phosphoric acid is also used in other applications including food flavoring, soft drinks, pharmaceuticals, dental products, cosmetics, and skin care products. The market is anticipated to grow steadily with about 2-5 % yearly reaching 17 million dollars in 2026, with increasing population and bio-fuels demand contributing to growth.
Phosphoric acid is produced by mining the naturally occurring phosphate rock. There are two ways to produce the acid; via wet process, which is most used as about 80 % or the acid is produced this way, or by thermal process. The wet process consists of 3 steps: reaction, filtration and concentration. Phosphate rock is treated with sulfuric acid H2SO4 for dissolution of the phosphate rock in so called acidulation reaction. By optimizing the sulfuric acid concentration, a higher decomposition and better quality of phosphates can be obtained.
The K-PATENTS® Process Refractometer PR-43-GP monitors the concentration of final product. As reaction step creates heat in the reactor, it is also necessary to monitor the sulfuric acid concentration to regulate the heat load. The refractometer’s Ethernet and mA output signals can be used for automatic control of the evaporator, ensuring the specified concentration is always obtained, while optimum energy consumption is maintained.
Application Note ref: 4.01.08 Wet Process Phosphoric Acid Production (PDF)