White Sodium Silicate Fluoride Powder For Inorganic Material 2.68 Density

Sodium Fluorosilicate powder commonly used in the inorganic material binding with the water glass

►Description 

Sodium fluorosilicate appears as white crystal, crystalline powder or colorless

hexagonal crystals. It is odorless and tasteless. Its relative density is 2.68; it has

moisture absorption capability. It can be dissolved in a solvent such as ethyl ether

but insoluble in alcohol. The solubility in acid is greater than that in water. It can be

decomposed in alkaline solution, generating sodium fluoride and silica. After

searing (300 ℃), it is decomposed into sodium fluoride and silicon tetrafluoride. It is

poisonous!In 25 degrees, the sodium fluorosilicate has its water solubility being

0.78%. Upon production, addition of an excess amount of sodium sulfate or sodium

chloride can increase the concentration of sodium ions in the system, thereby

increasing the solubility product of fluorine silicate and sodium ions, so that sodium

fluoride can be subject to more complete precipitation. Sodium fluorosilicate is the

byproduct in the production of calcium phosphate or the production of fluoride salt

in aluminum factory. It generally appears as a white crystalline powder with low

solubility in water (being 1% or less at room temperature), and the water solubility

increases slightly with increasing temperature. The aqueous solution of sodium

fluorosilicate is acidic (pH3). This is due to that its hydrolysis product contains

hydrofluoric acid. Reduction of the acidicity of the solution facilitates the hydrolysis

of sodium fluorosilicate. When pH is lower than 3.5-3.55, the hydrolysis reaction is

stabilized. When the pH is equal to 4, the hydrolysis reaction rate is significant.

When the pH value is equal to 8-8.5, the sodium fluorosilicate can be completely

hydrolyzed to exhibit as silica gel and precipitated out. Therefore, when sodium

fluorosilicate is added to the water glass, in addition to hardening effect of

precipitation of silicon dioxide gel caused by the neutralization of the sodium

hydroxide in the solution of water glass, the sodium fluorosilicate itself is also a

source of silica gel.

►Specification 

►Toxicity

      This product is toxic with stimulation effect on the respiratory organ. People of

mistakenly oral poisoning will get severe symptoms of damage to the

gastrointestinal tract with the lethal dose being 0.4~4g. During the working of the

operator, they should wear the necessary protective equipment to prevent

poisoning. Production equipment should be sealed and the workshop should be

well ventilated.

►Production method

     Calcium superphosphate byproduct method: use sulfuric acid and ground

phosphate rock for production of superphosphate or fluorine-containing waste gas

during extraction of phosphate with water absorbing silicon tetrafluoride to make it

into fluorosilicate. When the concentration of fluorine acid solution reaches 8% to

10%, stand static for clarification and remove the impurities with the clarified

fluorine silicate solution being added of sodium chloride (being excess of about

25%) for reaction of sodium fluorosilicate. Further go through centrifugation

isolation, washing, air drying at a temperature below 300 ℃ and then pulverize to

obtain the finished product of sodium fluorosilicate.
 

H2SiF6 + 2NaCl → Na2SiF6 + 2HCl

►Storage characteristics

Treasury: ventilation, low-temperature and drying; store it separately from food and

acid

►Application 

It is most commonly used in the inorganic material binding with the water glass.