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Purification of silicon is by conversion to trichlorosilane, followed by distillation. No fluorine is involved.

The side by products of this process are very quickly hydrolyzed to silica and hydrochloric acid, neither of which is something to worry about as a persistent pollutant.

The volumes are also small. Just a few hundred thousand tons of silicon are used every year for all electronics (PV and ICs combined).

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HF is used in boatloads for silicon wafer manufacturing. Not sure about solar. This might be what they're referring to?

But...(at least in the US), wafer manufacturing is highly regulated and focused on safe waste handling...

I'm not sure how much that is, though. On the other hand, manufacture of aluminum from ore requires several kilograms of HF per ton of aluminum. So perhaps the HF usage in PV manufacture is dominated by the production of the aluminum frames for the modules.

I think the dominant consumer of HF, industrially, is in petroleum refineries, where HF is used in alkylation units.

As you wish.

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