Preparation Method Of Ammonium Fluoride

Liquid phase method

① Neutralization method: In lead or plastic containers, put quantitative hydrofluoric acid. Cool with water outside the container, and slowly pass ammonia gas under stirring until the Ph value of the reaction liquid reaches about 4. The reaction liquid was cooled and crystallized, centrifuged and dried by air flow to prepare ammonium fluoride product. The reaction principle is as follows:

NH3+HF→NH4F

(2) Ammonia ammonia preparation of ammonium fluoride: using fluosilicic acid or ammonium fluosilicic acid and water as raw materials, the ammonia and fluosilicic acid are quickly reacted to produce silica white seed, water, fluosilicic acid and ammonia water are added for reaction, by controlling the reaction pH and temperature to produce silica white and ammonium fluoride, and then through a series of follow-up treatment to get product silica white and ammonium fluoride;

③ Preparation of ammonium fluoride by ammoniating ammonium carbide: The preparation of ammonium fluoride by ammoniating fluorosilicic acid with ammonium carbide was mainly reported in the literature by Lu Aijun, Liu Xiaohong, Wang Heyun, etc. It is characterized as follows: the raw material ammonium carbide is purified by recrystallization, the fluosilicic acid is purified by auxiliaries, and the purified ammonium carbide is ammoniated fluosilicic acid to produce high-purity ammonium fluoride and silica.

Gas phase method: Take 75g 40% hydrofluoric acid in a platinum dish or teflon container, cool it, and then slowly pass in excess ammonia gas. The NH4F precipitated is filtered out by suction filtration. [2 The reaction principle is as follows:

NH3+HF→NH4F

Sublimation method: The mixture of 1 part ammonium chloride and 2.3 parts ammonium hydrogen fluoride is placed in a platinum dish, the platinum dish is covered with a concave cover, and cold water is placed on the cover to cool it. The platinum dish is slightly heated, and the sublimed ammonium fluoride condenses on the dish lid to obtain small prismatic crystals. The reaction principle is as follows:

NH4Cl+NaF→NH4F+NaCl