| 摘要 |
Removing fine-grain silicon material comprises: selecting ground silicon material; supplying the ground silicon material to a reaction vessel; adding an aqueous or water-containing solution of a base to the ground silicon material; adding an acid or water to terminate etching and cause rapid sedimentation of a suspension in form of a relatively coarse-grain solid; and providing the sedimented relatively coarse-grain solid for further processing or withdrawing a solution formed above the relatively coarse-grain solid, or both. Removing fine-grain silicon material with grain sizes of less than 1 mu m from ground silicon material having grain sizes of less than 500 mu m comprises: selecting ground silicon material that exhibits a predominantly brown color in an aqueous suspension, indicating that a considerable fraction of the ground silicon material has a grain size of less than 0.25 mu m; supplying the ground silicon material to a reaction vessel; adding an aqueous or water-containing solution of a base to the ground silicon material, causing an etching process which produces a significant volume of foam and chemically removes a fine fraction with a grain size of less than approximately 1 mu m; adding an acid or water to terminate etching and cause rapid sedimentation of a suspension in form of a relatively coarse-grain solid; and providing the sedimented relatively coarse-grain solid for further processing or withdrawing a solution formed above the relatively coarse-grain solid, or both. An independent claim is an apparatus for removing fine-grain silicon material with grain sizes of less than 1 mu m from ground silicon material having grain sizes of less than 500 mu m comprising: a reaction vessel constructed by interconnecting a storage vessel for the ground silicon material, a storage vessel for a base or a aqueous or water-containing solution of a base, and a storage vessel for an acid; a controller for controllably supplying the ground silicon material, the base or the solution of the base and the acid to the reaction vessel; a device for agitating contents of the reaction vessel; a unit for interrupting supply of acid to the reaction vessel either at a time predetermined by a timer or at a time determined by a measuring device; a first withdrawal device installed on the reaction vessel for removing a sedimented fraction of a relatively coarse-grain solid; and a second withdrawal device installed on the reaction vessel for removing a liquid residing above the sedimented fraction. |
