Abstract:
The invention comprises a multi-vessel reaction apparatus useful for reacting phosphate rock and sulfuric acid in which the reaction slurry undergoes intra- and inter- vessel circulation (preferably through a draft tube). The solution portion of the slurry in a first vessel or set of vessels (the "dissolver") is preferably maintained at at lower sulfate ion concentration and the solution portion of the slurry in the second vessel or system of vessels (the "crystallizer") is preferably maintained at a positive sulfate ion concentration. Also preferred are means for maintaining the second vessel or set of vessels at a reduced pressure. Most preferred is that means be included in at least one said vessel for incorporating a crystal modifier (e.g. a sulfonic acid, a sulfonic acid salt, tall oil fatty acids or alkoxylated or esterified tall oil fatty acids) in the crystallizer. The system can be used in the anhydrite, hemihydrate or gypsum types of processes.
Abstract:
Phosphate rock and sulfuric acid are reacted to produce phosphoric acid and calcium sulfate by means of the hemihydrate wet process. In this improved process, the calcium sulfate hemihydrate is crystallized from solution in the presence of an organic sulfonic acid or a derivative thereof. The organic sulfonic acid or its derivative improves the growth of the calcium sulfate hemihydrate crystals and thus improves the filtration rate of the slurry produced in this improved process.
Abstract:
P.sub.2 O.sub.5 values occluded in the crystals which are precipitated during the hemihydrate process for manufacturing phosphoric acid are recovered by dissolving and recrystallizing the hemihydrate crystals as dihydrate crystals in an acidic environment having a P.sub.2 O.sub.5 concentration of from about 0.1% to about 10% and a free sulfate concentration in the range of about 0.1% to about 10%. Water is used to wash the dihydrate filter cake, and the filtrate from this wash is used to redissolve the hemihydrate crystals. The free sulfate values are preferably supplied to the dihydrate crystallizer as sulfuric acid.
Abstract:
High quality phosphoric acid is produced from phosphate rock and high alumina pebble which is a byproduct of phosphate rock mining operations. The rock or pebble with or without comminution is digested in phosphoric and sulfuric acid and the resultant phosphoric acid contains the metallic ions normally present in the treated rock and pebble. The metallic ions are then extracted from the acid by ion exchange with a water-immiscible organic sulphonic acid compound (preferably in the presence of an organophosphate or phosphonate). After phase separation the organic phase containing the extracted metallic ions can be regenerated. The process is especially useful when the digestion is done at a P.sub.2 O.sub.5 concentration and temperature which produces calcium sulfate hemihydrate.
Abstract:
Phosphate rock and sulfuric acid are reacted under conditions which result in the formation calcium sulfate hemihydrate and phosphoric acid of about 30% to about 55% P.sub.2 O.sub.5. A two vessel reaction system is used in which the reaction slurry undergoes inter- and intra- vessel circulation. This results in excellent dispersion of reactants and minimization of temperature and concentration gradients throughout the slurry.
Abstract translation:磷酸盐岩和硫酸在导致形成约30%至约55%的P2 O 5的硫酸钙半水合物和磷酸的条件下反应。 使用反应浆料经受血管内和血管内循环的二血管反应系统。 这导致反应物的优异分散和整个浆料中温度和浓度梯度的最小化。
Abstract:
A process for the extraction of metallic impurities from an unpurified aqueous phosphoric acid phase by solvent extraction employing an organic extractant phase containing an organic sulfonic acid in its H.sup.+ form. After the extraction step and separation of the organic extractant phase from the aqueous phosphoric acid phase, residual P.sub.2 O.sub.5 values are recovered from the organic extractant phase by washing the organic extractant phase with a wash phase consisting of water or dilute phosphoric acid. The sulfonic acid in the organic extractant phase can be regenerated to its H.sup.+ form with a mineral acid and recycled.
Abstract:
Water immiscible organic acid phosphates used in conjunction with water immiscible organic sulfonic acids results in an improved process for the purification of phosphoric acid. An increase in the extraction of ionic metallic impurities and a decrease in the extraction of P.sub.2 O.sub.5 values from the aqueous phosphoric acid phase .[.is.]. .Iadd.are .Iaddend.observed in the improved solvent extraction process.
Abstract:
Phosphoric acid is prepared from phosphate rock and sulfuric acid by using a reaction train comprising a dissolving slurry and a crystallization slurry maintained at different sulfate levels. Both inter and intra vessel circulation are used at high rates to minimize reagent concentration gradients and temperature gradients and provide a suitable crystallization environment. Preferably, the intra vessel circulation is substantially in plug flow, as through a draft tube.
Abstract:
Impure phosphoric acid containing uranium values is pretreated with a water immiscible organic sulfonic acid, preferably in conjunction with a water immiscible organic acid phosphate compound, for extraction of ionic metallic impurities and organic impurities to produce pretreated phosphoric acid containing uranium values. Pretreated phosphoric acid is contacted with a water immiscible extractant comprising an organic uranium-extracting agent, preferably an organophosphorus compound, dissolved in a water immiscible organic diluent to produce uranium-depleted phosphoric acid and uranium-enriched extractant. Uranium is recovered from the uranium-enriched extractant.