Where Does the F Come From? by Robert Mann
Those of us who envisage the end of the monstrous blunder fluoridation have sometimes wondered what alternatives can be proposed for getting rid of the toxic industrial wastes which are the feed materials trickled into water supplies by this immoral practice. It is not strictly our task to solve this waste problem, but practically speaking it may help if we can point out possible new waste-disposal methods for use when fluoridation is stopped.
In a recent attack on fluoridation, the popular Dr Mercola said sodium fluoride was the first of the fluoride waste materials to be used for fluoridation, but now is rarely used”.
This will be news to many of those concerned about fluoridation. We have been accustomed for decades to the aluminium (N. Amer. ‘aluminum’) smelting industry getting rid of its concentrated toxic byproduct by sale as sodium fluoride, main source of F for fluoridation of water supplies. This lucrative route for disposal of concentrated toxic waste by declaring it shall be dispersed in water supplies has now been largely taken over by the superphosphate industry.
In New Zealand, however, sodium fluoride is still used by one or two of the smallest Fation plants. Whether it comes from the smelter at Tiwai Pt or from China has yet to be researched.
But a third source of F is also used – sodium fluorosilicate Na2SiF6 derived from the superphosphate wastes.
In New Zealand, however, sodium fluoride is still used by most of the smaller Fation plants. Whether it comes from the smelter at Tiwai Pt or from China has yet to be researched.
Let us sketch the involvement of the element fluorine in these two industries, and then glimpse the changes in relative importance.
Cryolite Na3AlF6 is a main chemical form of the element fluorine in the earth’s crust (though not as abundant as fluorite CaF2). This mineral turns out to be useful as a flux in smelting alumina Al2O3 (after it has been refined from the ore bauxite) to the metal aluminium. This high-current electrolytic smelting proceeds in a solution of alumina in cryolite which acts as a flux, at a mere 1000 °C (compare the melting point of alumina which is just over 2000 °C). Among several byproducts containing the element fluorine, the salt sodium fluoride NaF is the most notorious. This material has been the quintessential example of a toxic waste transmogrified into a public asset.
The other classic example arises in superphosphate factories. Concentrated sulfuric acid converts rock phosphate into the inorganic fertiliser known as superphosphate (a propagandistic, as distinct from chemical, name). Trapped in precipitators to decrease air pollution from these factories’ flues are volatile byproducts, a mixture sold as H2SiF6 hexafluorosilicic acid (best name), or fluosilicic acid (older name), or a half-dozen other names. The city of Hamilton has been paying $40,000/y for this waste material. Minor components in this waste have been pointed out as minor objections to fluoridation when this waste mixture is used for fluoridation, but the main component H2SiF6 is the chief concern, hydrolysing when dissolved at waterworks to create fluoride F-.
We gather that the aluminium smelting industry has been increasingly recycling sodium fluoride as natural cryolite becomes rarer. The most abundant natural F-containing mineral, fluorspar CaF2, is used for this newer chemistry.
The trend mentioned by Dr Mercola may offer us some encouragement, to the extent we believe the superphosphate industry is less politically powerful than the aluminium-smelting industry. Wouldn’t it be nice if instead of mining new fluorspar to make cryolite, the hexafluorosilicic acid waste could go into new chemistry at the aluminium smelters?
I hasten to add that I am in a sense joking – not aware of any such specific chemical prospects. But if we can point helpfully to any disposal method for hexafluorosilicic acid, that would be a practical help towards cessation of fluoridation. The economic & political pressure from the aluminium industry for fluoridation may be decreasing, and we should therefore focus more on the current main offender, and encourage research on disposal methods.
Dr Mann was Senior Lecturer in Biochemistry and in Environmental Studies, U of Auckland, during which period he advised successive Ministers of Health on the Toxic Substances Board. He was instrumental, with the late Dr John Colquhoun, in exposing the Hastings swindle.