Study On Dry Synthesis Of Potassium Fluoride By Ammonium

Potassium fluoride, a kind of high valued inorganic fluoride salt, usually produced by hydrogen fluoride and potassium hydroxide in the industy,, costs too much at present. However, the reaction temperature is too high when potassium fluoride is produced by fluorosilicic acid or potassium fluosilicate in drying process, so industrialized production can’t be achieved, either.Ammonium fluoride can be made of fluosilicic acid, one of the byproducts of wet-process phosphatic fertilizer production. It not only reduces the production cost, but also variegates high value-added products in phosphate fertilizer factory. As ammonia and a small amount of water escaped from the reaction of ammonium fluoride and potassium hydroxide, they can be absorbed by fluosilicic acid and then converted into raw material ammonium fluoride, resource recycling become realized. And problems of large energy consumption, critical equipment demand of thermo stability and corrosion resistance through traditional drying process was solved.Single factor experiment and orthogonal experiment was combined as research method, with the purity and yield of potassium fluoride products as indicators. Dry process for producing potassium fluoride, with ammonium fluoride and potassium hydroxide as raw materials was systematically studied. The optimum process conditions was determined. In addition, because the specific surface area of potassium fluoride reduces by moisture absorption and caking, to maintain its good properties, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate was chosen to be the desiccating agent. After adding the desiccating agent, the purity and moisture absorption rate of anhydrous potassium fluoride was studied. The results showed that:(1) Optimum process conditions for dry-process production of potassium fluoride by ammonium fluoride and potassium hydroxide.Mole ratio of raw material n(NH4F):n(KOH)= 1.03:1, reaction temperature is 100 ℃, reaction time is 40 min, the propeller agitatorspeed is 100 r/min, the drying temperature is 210℃, the drying time is 2.5 h.Under optimum process conditions, the purity of potassium fluoride products reached 98.87%, the yield of fluorine(according to fluorine) reached 96.15%, the product quality meets the requirement of HG/T 2829-2008.(2) based on the research in the content of additive, we know that the best addition is m(additive)/m(anhydrous potassium fluoride)=0.09% of the two kinds of additive. Anhydrous potassium fluoride of moisture absorption rate was studied in different environment temperature, environment humidity and storage time, the results showed that moisture absorption rate of anhydrous potassium fluoride was obviously reduced when either of the desiccating agents was added, and sodium dodecyl sulfate is better than dodecyl benzene sulfonic acid sodium. At the same time, the anhydrous potassium fluoride should be stored in a cool, dry place, and the storage time should be shortened as much as possible.