When in 1896 all buffalo bones disappeared from the American plains due to the production of phosphorus, phosphoric acid and other phosphorous products, companies are thinking of replacing bone with a more reliable source, and so they are turning to phosphate mineral ores
The wet process is the most common method for industrial Phosphoric acid production. Phosphate rock, which is a naturally occurring mineral containing phosphorus, is mined and processed to remove impurities. The Rock is typically ground to a fine powder to increase its surface area. The powdered phosphate rock is mixed with sulfuric acid. The reaction between the rock and the acid results in the formation of phosphoric acid (H₃PO₄) and calcium sulfate (gypsum). The reaction typically takes place in large reaction vessels known as digesters.
The mixture of phosphoric acid and calcium sulfate is then filtered to separate the solid calcium sulfate from the liquid phosphoric acid. The calcium sulfate can be further processed for use in various applications such as construction materials. The filtered phosphoric acid is typically diluted, and the water content is reduced through evaporation or other concentration methods. This step increases the concentration of phosphoric acid in the final product.
Phosphate Rocks are generally available in the form of hydroxides and fluorides. Apatite is also the most important phosphate rock that is used to produce industrial and edible phosphoric acid. There are many impurities in this rock that can reduce the efficiency of phosphoric acid. These impurities also cause more corrosion of the materials. In 1812, the company Quigent in Lyon, France, discovered a way to produce pure phosphorus by adding hydrochloric acid to the bone, which was fully produced by the French government until 1872, from which phosphoric acid, along with other phosphorus products, was produced.
It was during these years (1840) that the importance of using phosphoric acid in the agricultural industry as fertilizer and its applications in agriculture and physiology was discussed by Justus van Liebig in the book named Organic Chemistry. In the same book, the scientist referred to the insoluble phosphate in bones and Minerals and said that by reacting this phosphate with sulfuric acid, a nutritious compound could be obtained for plants.
When in 1896 all buffalo bones disappeared from the American plains due to the production of phosphorus, phosphoric acid and other phosphorous products, companies are thinking of replacing bone with a more reliable source, and so they are turning to phosphate mineral ores. But before that, many of them went bankrupt due to rising bone prices. Today, phosphoric acid is prepared from phosphate rocks in two general and dry methods.
The thermal process, also known as the furnace process or dry process, is an alternative method for phosphoric acid production. Elemental phosphorus (P₄) is burned in the presence of excess air, which converts the phosphorus into phosphorus pentoxide (P₂O₅). This reaction typically occurs in a furnace or reactor. The resulting phosphorus pentoxide is dissolved in water to form phosphoric acid. The Chemical equation for this reaction is: P₂O₅ + 3H₂O → 2H₃PO₄. The phosphoric acid solution is typically filtered to remove any impurities. The filtered solution is then concentrated through evaporation or other methods to increase the phosphoric acid concentration.
Both the wet process and the thermal process have their advantages and disadvantages. The wet process is more commonly used due to its lower energy requirements and higher phosphoric acid purity. The thermal process, on the other hand, can be advantageous in regions with limited water resources as it does not require large quantities of water for acidulation. Environmental considerations and sustainability efforts are becoming increasingly important in phosphoric acid production, with efforts to minimize waste and reduce environmental impacts.
