Method for preparing high-purity potassium fluoride by reaction of potash water glass and fluosilicic acid or potassium fluosilicate

The invention discloses a method for preparing high-purity potassium fluoride by reaction of potash water glass and fluosilicic acid or potassium fluosilicate. The preparation method comprises the following steps: adding water into a reaction kettle, adding part or all of fluosilicic acid or potassium fluosilicate while stirring, and preparing slurry from fluosilicic acid or potassium fluosilicateand water; raising the temperature to 40-70 DEG C, adding part of potash water glass into the slurry, and taking silicon dioxide particles separated out by reaction as seed crystals for separating out silicon dioxide by subsequent reaction; continuously heating the materials to 75-95 DEG C, and simultaneously adding the rest fluosilicic acid or potassium fluosilicate and potash water glass into the slurry at a constant speed to finish alkaline hydrolysis reaction; carrying out solid-liquid separation on the reaction liquid, and washing and drying the solid to obtain white carbon black; and carrying out concentration