The New Zealand Institute of Chemistry gives an impartial description of where the fluoridation chemicals come from and how they are manufactured.
|Step 1 – Production of SiF4
The superphosphate production process results in the evolution of carbon dioxide, steam
and SiF4. This SiF4 is an environmental pollutant and so is removed from the gas stream
and used to produce fluorosilicic acid.
|Step 2 – Hydrolysis of SiF4
The SiF4 is removed from the gas stream by contacting the gas with water droplets. This
water hydrolyses the SiF4 as follows:
3SiF4 + 2H2O → 2H2SiF6 + SiO2
The resultant hydrofluorosilicic acid (H2SiF6) is used for fluoridating drinking water