Patent ID: 8920761
Filing Date: 2014-12-30
Classification: C01B,C01P

Abstract:
1. A method for producing high purity silicon comprising: providing molten silicon containing 1-10% by weight of calcium; casting the molten silicon; crushing the cast silicon to form silicon particles; subjecting the silicon particles to a first leaching step in an aqueous solution of HCl and/or HCl+FeCl subjecting the first leached silicon particles to a second leaching step in an aqueous solution of HF and HNO subjecting the second leached silicon particles to heat treatment at a temperature of between 1250° C. and 1420° C. for a period of at least 20 minutes, wherein the second leached silicon particles are in particulate form during the heat treatment; and subjecting the heat treated silicon particles to a third leaching step in an aqueous solution of HF and HNO