| To improve the process of potassium sulphate prepared from phosphogypsum (under study, no product, only method) in ammonia solution, the addition of some organic solvents can improve the state of reaction system, thereby different organic solvents (methanol, ethanol and other 11 kinds of organic solvents) were investigated to add into the reaction system on the yield of potassium hydroxide. Depending on the solvent and the concentration of potassium results yield, we preliminary selected methanol, ethanol, propanol, isopropanol and acetone yield of the five greater impact in improving the solvent potassium.Ammonia-methanol, ammonia-ethanol, ammonia-isopropyl alcohol, ammonia-propanol and ammonia-acetone composition of mixed solvents were added to reaction system, and then five major factors on the yield of potassium were researched, which were as follows, solvent concentration, reaction time, initial concentration of ammonia, liquid to solid ratio and the charge ratio. The results showed that the ammonia-ethanol was the best. Ammonia-ethanol system was conducive to the improvement of conditions, which can effectively improve the yield of potassium hydroxide.The direct preparation process of ammonia-ethanol solution of potassium sulfate from phosphogypsum was further studied. The optimum process conditions were obtained:8% ethanol concentration,25% ammonia solution concentration,reaction temperature was 25℃,reaction time was 1.0 h,liquid to solid ratio was 5.5:l,charge ratio was 1.20:1.Under these experimental conditions, the product of Potassium hydroxide mass fraction was 40%, the potassium hydroxide yields was about 75%, the Chloride content was 1.74～1.85%.The quality of potassium sulfate achieved to the National Agricultural qualified product, by-product calcium chloride achieved to industrial quality products. Ethanol and ammonia can be recovered by simple distillation. The operating temperature were about 50℃and 90℃,85% ethanol was reclaimed. |
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