The Preparation Of High Activity Of Potassium Fluoride By Fluoride Containing Wastewater Improvement Research

In phosphate fertilizer production process will produce a large number of sub-fluorinated gasses,which absorbed by the water and then generated fluoride acid,most companies use fluosilicic acid,the by-produce of phosphate fertilizer,to prepare sodium fluorosilicate,but the price of sodium fluorosilicate was cheap and it had no market.Even sodium fluorosilicate was discharged into rivers which not only result in a waste of fluorine and silicon resources,but also make a serious pollution to the environment.It can be seen,recycling low concentrations of fluoride acid and preparate high value potassium fluoride production is a subject of great value research.In this improve thesis,using phosphate fertilizer byproduct fluoride acid and potassium hydroxide and potassium chloride,adopting potassium chloride instead of part of potassium hydroxide,as raw material to generate highly active potassium fluoride by two-step method,using potassium chloride to replace parts of the potassium hydroxide react with fluosilicic acid to preparation of highly active potassium fluoride,and by-product the silicon dioxide.This paper discussed how the reaction temperature,the concentration of potassium hydroxide,the pH on the end of the reaction and ingredients than effect the purity and yield of the production of highly active potassium fluoride in the small-scale test phase.The optimun condition are reaction temperature of80 ℃,potassium hydroxide concentration of 50%,pH on the end of the reaction of 9.7.Potassium fluoride products which produced by the method of enrichment crystallization can meet the requirements of HG/T2829-2008.And Potassium fluoride products produced by the method of spray drying can conform to the quality index of the highly active potassium fluoride.In the experiment of cyclic multiple washing water circulation,the yield of highly active potassium fluoride products improved significantly,and the yield can up to 93%.The quality can also meet the standard requirements.The improving technology of preparation of potassium fluoride by fluoride silicate can make the raw material cost greatly reduced.At the same time,it greatly reduces theneed to evaporation of water,save the heat energy,has important economic and environmental significance.In the enlarge experiment,the potassium fluoride dried by spray drying method.Detected and characterized the potassium fluoride,the purity of it is 99.04%,the particle sizes are 40-50μm,BET specific surface area are 4.2m~2/g,and all of these indicators can meet the high activity potassium fluoride product requirements.Detected and Characterized the by-product silicon dioxide,the particle sizes are240-350 nm,with a purity of 95.64%,BET specific surface area are 30m~2/g,DBP oil absorption of 2.58cm3/g,the other indicators also meet the requirements HG/T3061-1999.In the enlarge experiment,the concentrations of potassium hydroxide is the concentrations of the industrial grade liquid potassium hydroxide.The optimum conditions for industrial production are reaction temperature of 80 ℃,concentration of potassium hydroxide of 48%,pH on the end of the reaction of 9.6.