Wacker Chemie Ag

Krauss-maffei Wegmann Gmbh & Co. Kg

Knds Deutschland Gmbh & Co. Kg

Wolfgang Stoiber

Hanns Wochner

Walter Haeckl

Barbara Mueller

Christian Gossmann

Elmar Bandmann

Manfred Schuhmann

Walter Häckl

Barbara MÜLLER

Installation of a shield around a Siemens reactor prior to harvesting polysilicon rods produced therein allows the upper, bell jar-like shell to be removed for cleaning, while protecting the polysilicon rods from contamination and increasing safety of nearby personnel. The polysilicon rods are harvested while the shield is present.

Process for producing polycrystalline silicon

In a method for recovering acid from an aqueous etching mixture containing HF, HNO, HSiFand HNOwhich has been used for purifying polycrystalline silicon, the used etching mixture is distilled progressively so that approximately from 20 to 50 wt. % of the mixture is distilled off as dilute acid containing more than 90 wt. % of the silicon dissolved as hexafluorosilicic acid in a first fraction, and the water contained in the used etching mixture having been reduced by approximately 10-30 wt. %, this water-depleted mixture is then concentrated by evaporation to a residue of about 1 to 5 wt. % of the initial amount of used etching mixture during which a second fraction is distilled off, and the residue is disposed of.

Method for processing an etching mixture which is formed during the production of highly pure silicon

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Eggenfelden, Germany

Wolfgang Stoiber