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Silicon for the Chemical and Solar Industry XIII
Kristiansand, Norway, June 13 – 16, 2016
High purity silicon sizing by high voltage pulse power
technology
Johannes Kaeppeler, Marion Morach
SELFRAG AG, Switzerland
Abstract
Size reduction of solid high purity silicon by pneumatic hammer or by jaw crusher
requires manual operation steps which are costly and difficult to reproduce, it leads to
unwanted losses and contamination, and particles shapes which are not suitable for an
efficient and dense filling of crucibles. The presented method aims to improve the
crushing process by using High Voltage Pulse Power technology. Pulses with energy
of up to 750 Joule/pulse at 170-200kV are introduced into the silicon to achieve a
controlled size reduction of the silicon. The energy is introduced by 2 electrodes and
reaching the Si rod or pieces through de-ionized water. Beside the good control of
particle shape and size, the lowest contamination levels are reached due to no physical
contact of the crushing unit with the silicon. This supports a more efficient silicon
sizing process and decreases the volume of potentially environmentally-hazardous
chemicals required as less etching is required. The controllable and accurate size
distribution reduces waste and off-spec material.
Purpose of the work
Key purpose of the work is to introduce and develop a state of the art process to the
Si- industry to increase production yield, save costs and produce higher quality final
products. To develop an environmental friendly process is taken into consideration
with the recycling possibility of off-spec material as well as the required low energy
consumption of the overall process. The technological implementation of the achieved
specifications are used for the design of continuous operating plants at customer sites.
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