It seems someone would have thought of generating the HSiCl3, purifying it, and decomposing it in the same plant, so the HCl could be recycled. 
I suspect the HSiCl3 is first made in a crude form, then shipped to a separate location where the purification is done. Crude, dirty, bulk scale in one location, refinement in the other, but it would seem that could be changed with a reasonable effort.
Since we're producing megatons of Cl2 by the chloralkali process, why not investigate using HCl as the electrolyte instead ? No alkali would be produced, but the valuable products H2 and Cl2 would find plenty of uses. (OTOH, one should avoid electrolytic processes as energy sinks, especially for FFs.) Perhaps the Deacon process could be modernized ?
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