Abstract: A method for lowering the risk of contamination during comminution of solid silicon fragments produces in a first step a temperature gradient in the solid silicon fragments. This temperature gradient results from the action of heat applied from the outside. A second temperature gradient is then produced, whose direction is rapidly at least partly reversed in a second step. This treatment effects a decompacting which makes it possible to use, in a subsequent mechanical comminution step, tools whose contact surfaces are composed of silicon or of hard materials, for example, based on nitride or carbide. The product obtained is remarkable for its uniform grain size distribution and also for its high purity in fine grain size categories. In addition, the low forces required for the comminution makes possible a longer service life for the tools used.

Abstract: A process for the purification of silicon by the action of one or several acids, wherein silicon is established as a stationary phase and one or several acids are caused to form mobile phases for traversing the stationary phase under pressure and absorbing the impurities from the silicon during the passage, leaving behind the silicon with a higher degree of purity.