Acidification of sodium fluosilicate with concentrated sulfuric acid to produce silicon tetrafluoride and anhydrous hydrogen fluoride

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Sodium fluosilicate is acidified with concentrated sulfuric acid to produce silicon tetrafluoride and anhydrous hydrogen fluoride. I’ve found numerous patents and publications on this topic; I think it’s a good manufacturing process. Solid sodium fluosilicate is much easier to transport than fluosilicic acid, and its cost is also lower. The sodium sulfate produced as a by-product can be returned to phosphate fertilizer factories, where it reacts with fluosilicic acid to regenerate sodium fluosilicate. There are no wastewater or waste residues generated. After silicon tetrafluoride and hydrogen fluoride are separated and purified, silicon tetrafluoride can be used to produce silica gel or silanes, while hydrogen fluoride can be sold directly. Compared to manufacturers who use concentrated sulfuric acid and fluorosilicic acid to produce anhydrous hydrogen fluoride, as they need to recover fluorine to make hydrogen fluoride, the method involving concentrated sulfuric acid and sodium fluorosilicate, which results in the production of silicon tetrafluoride and thus the loss of a large amount of fluorine, appears less advantageous. However, for manufacturers who want to produce silanes or silica gel, this method offers significant advantages; its cost is surely much lower than that of the pyrolysis of sodium fluorosilicate. Then why do some people not use this method and instead opt for the pyrolysis route to produce silicon tetrafluoride? It seems that there are no mature devices for the process using concentrated sulfuric acid and sodium fluosilicate, nor are there any mature devices for pyrolysis. Is it because silicon tetrafluoride and hydrogen fluoride are difficult to separate and purify, or is there some other reason? Why has no one developed equipment for this process?