Abstract: Phosphoric acid is produced by a wet process in a homogeneous medium from calcium phosphate ore, sulphuric acid and a continuously added aqueous solution of recycled acid.Part of the phosphate is treated in a primary reaction medium, prepared separately and differing in composition from the final medium sought. By regulating the compositions of the various reaction media, the present process advantageously increases the concentration of the phosphoric acid produced and/or enhances the quality of filtration, along with other advantages.The process can advantageously be applied for the economic treatment of low-grade, poorly reactive or unground phosphates.

Abstract: The air cooling of exothermic reaction vessels is improved by providing a cooling air recirculation loop wherein substantial amounts of the cooling air are recycled through the system with but a small fraction thereof being discharged to ambient, and after the condensable/soluble off-gases are depleted therefrom and with addition thereto of but minor amounts of additional feed air. Such technique is well suited for controlling the temperature of the digestion of phosphate rock with sulfuric acid, in the known wet-process for the production of phosphoric acid.

Abstract: A continuous procedure is disclosed for the wet-process manufacture of phosphoric acid in a reaction zone and continuously cooled by means of evaporation into air circulating at the surface of the reaction zone. The evaporated gases are scrubbed by using part of the water needed for the methodic washing of the calcium sulfate, whereby the solution obtained is collected and passed into the reaction zone in such a way as to cause the soluble gaseous products to return to the reaction medium, from which they are collected with strong acid, which constitutes production. The procedure gives rise to no liquid pollutants, particularly fluorine, and does not increase the amount of water consumed.