Sodium fluoride I believe everyone should have heard that sodium fluoride is most commonly used in toothpaste, fluoride can effectively prevent dental caries, especially suitable for children and the elderly who are prone to caries. Here is a brief introduction to the basic knowledge of sodium fluoride.
Sodium fluoride formula
Sodium fluoride is a colorless shiny crystal or white powder with the chemical formula NaF, soluble in water (solubility 10°C 3.66, 20°C 4.06, 30°C 4.22, 40°C 4.4, 60°C 4.68, 80°C 4.89, 100°C5.08), hydrofluoric acid, slightly soluble in alcohol. The aqueous solution is weakly alkaline and dissolves in hydrofluoric acid to form sodium hydrogen fluoride, which can corrode glass.
Sodium fluoride production technology
A method for preparing sodium fluoride comprises the following steps: albite decomposition: albite, fluorite, 98% sulfuric acid in accordance with 1: (1.55 ~ 2.57) : The mass ratio of (3.28 ~ 4.62) was mixed, and the solid residue containing calcium sulfate, sodium sulfate and aluminum sulfate and the gas product containing silicon fluoride were obtained at 100℃ ~ 200℃ and autogenous pressure. Hydrolysis of silicofluoride: hydrolysis of silicofluoride in the gas product to obtain a hydrolyzed product containing silicofluoride solution; Preparation of slurry containing sodium fluoride and silica: The hydrolysis product is placed in the reactor, the temperature of 85℃ ~ 100℃, the mass percentage concentration of 25% ~ 55% sodium hydroxide solution is added to the reactor, and stir the solution in the reactor to reduce the pH value of the solution to 8 ~ 9 within 10 minutes to 20 minutes, to obtain a slurry containing sodium fluoride and silicon dioxide; Separation of sodium fluoride: continue to add the sodium hydroxide solution to the reactor so that the pH value in the reactor is ≥10, and at 95 ° C ~ 100 ° C constant temperature for 25 minutes to 35 minutes to precipitate sodium fluoride crystals, filter and dry the precipitated sodium fluoride crystals to obtain sodium fluoride finished products.
The role of sodium fluoride
In the coating industry, it is used as a phosphating accelerator to stabilize the phosphating liquid, refine the phosphating, and improve the performance of the phosphating film. Al3+, which has a harmful negative catalytic effect, is blocked in the phosphating of aluminum and its alloys, which makes the phosphating smooth for wood preservatives, agricultural insecticides, brewing industry fungicides, medical preservatives, welding flux, basic zincate galvanizing additives and enamel, paper and so on.
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