Various methods are used to Purification of phosphoric acid . Below are three examples of phosphoric acid purification. Phosphoric acid is a weak oxyacid that has many industrial applications depending on its purity. Phosphate ore contains many impurities including calcium, iron, aluminum, fluorine, uranium and …. Therefore, efficient treatment processes are required to produce pure phosphoric acid for various applications. Commercial grade phosphoric acid (MPA) is used in surface treatments and fertilizer production . Food grade phosphoric acid (FPA) is used in the production of salt for animal feed or in the acidity of food and beverages for human consumption. Pharmaceutical grade phosphoric acid (PPA) is produced for the pharmaceutical industry. Of the current production of phosphate ore, 137.6 tons per year, 1 is less than 4% for the food and pharmaceutical industries, but these two sectors require high-grade phosphoric acid. Phosphoric acid can be produced from phosphate ores using two main processes (A) Pyrometallurgical or thermal processes, which use phosphorus as an intermediate and release a pharmaceutical grade phosphoric acid. (B) Hydrometallurgical or wet processes include washing, solvent extraction, and precipitation steps in the thermal process. Phosphorus is produced first by reducing phosphate rock and then re-oxidation and hydration of phosphoric acid. Despite the production of very high levels of phosphoric acid, the thermal path has been gradually abandoned due to its expensive energy cost (only 5% of the total phosphoric acid was produced by thermal processes in 2007). 2 In the wet process, phosphate ores are usually washed with a mineral acid, usually sulfuric acid, and the resulting leachate is further purified to produce a higher degree of phosphoric acid. Currently, several hydrometallurgical methods, including precipitation, adsorption, ion exchange, reverse osmosis, nanofiltration are considered to achieve such purification, and the best practical results are obtained when combining chemical and solvent extraction methods. There are two main strategies for phosphoric acid purification: impurity removal or selective extraction. The oldest methods often belong to the first category and are based on the deposition of insoluble salts, even if the recovery of certain elements such as uranium attracts more attention. Today, most treatment methods belong to the second category, namely the selective extraction of H 3 PO 4 against impurities Unspoken Phosphoric Acid.
Solvent extraction is an economically efficient method that is widely used in the purification of wet phosphoric acid. In this method, microchannels are used to promote mixing and purification of phosphoric acid during continuous production. For this purpose, liquid extraction is performed for purification through a mixture of methyl isobutyl ketone / tri-butyl phosphate. In addition, the Box-Behnken experimental design method is used to investigate the liquid extraction process. The effect of various operating parameters such as solvent concentration (45-65 t by weight), temperature (18-28 ° C) and organic / aqueous phase ratio (2: 1-6: 1) with constant flow rate of 70 ml / l is investigated. To take. The microchannel can increase the sulfate extraction and removal percentage by more than 98% and 60% during a stay of 6.85 minutes. Purification of phosphoric acid by minimizing iron, copper, cadmium and fluoride Commercially produced phosphoric acid is purified using a wet process by minimizing iron, cadmium, copper and fluoride. Bentonite clay is known to remove humic acids and suspended solids from crude phosphoric acid. Efforts are made to minimize the amount of iron by adding potassium sulfate, calcium sulfate, and sodium sulfate separately. Silicon dioxide, sodium carbonate, potassium sulfate, in combination and amyl potassium xanthate are the main targets. The efficiency of potassium amyl xanthate in minimizing iron content is 79.19% with a slight decrease in P 2 O 5. Temperature, stirring time and amount of additives are studied. Minimization of fluoride from phosphoric acid is done using silicon dioxide followed by the addition of sodium carbonate. By adjusting the stoichiometric values, additives and heating temperature, the efficiency of fluoride minimization is 93.89%. Copper and cadmium are also removed.