may be practiced without one or more of these specific details or with other methods components materials etc in other instances well known structures associated with systems for making silicon including but not limited to vessel design and construction details metallurgical properties piping control system design mixer design separators vaporizers valves controllers or final control elements have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments unless the context requires otherwise throughout the specification and claims which follow the word u201c comprise u201d and variations thereof such as u201c comprises u201d and u201c comprising u201d are to be construed in an open inclusive sense that is as u201c including but not limited to u201d reference throughout this specification to u201c one embodiment u201d or u201c an embodiment u201d or u201c another embodiment u201d or u201c some embodiments u201d or u201c certain embodiments u201d means that a particular referent feature structure or characteristic described in connection with the embodiment is included in at least one embodiment thus the appearance of the phrases u201c in one embodiment u201d or u201c in an embodiment u201d or u201c in another embodiment u201d or u201c in some embodiments u201d or u201c in certain embodiments u201d in various places throughout this specification are not necessarily all referring to the same embodiment furthermore the particular features structures or characteristics may be combined in any suitable manner in one or more embodiments it should be noted that as used in this specification and the appended claims the singular forms u201c a u201d u201c an u201d and u201c the u201d include plural referents unless the content clearly dictates otherwise thus for example reference to a chlorosilane includes a single species of chlorosilane but may also include multiple.