Installation for refining silicon comprises a protective shield of refractory material with low thermal conductivity disposed between a crucible and the silicon charge

摘要

#CMT# #/CMT# Installation for refining silicon comprises a crucible with a base made of a refractory material with high thermal conductivity, a device for cooling the base, a protective shield of refractory material with low thermal conductivity disposed between the crucible and the silicon charge, and an induction coil disposed in or beneath the base for heating the charge. #CMT# : #/CMT# An independent claim is also included for refining a silicon charge in an installation as above by placing the charge on the protective shield, cooling the base and heating the charge with the induction coil. #CMT#USE : #/CMT# Installation for refining silicon, especially for use in solar cells. #CMT#ADVANTAGE : #/CMT# The difficulties and high costs involved in constructing a sectorized cold crucible are avoided (compare ). #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a silicon refining installation as above. 10 : Crucible side wall 12 : Side wall cavity 20 : Crucible base 23 : Induction coil(26) Cooling tube 30 : Protective shield 35 : Plasma torch. #CMT#CHEMICAL ENGINEERING : #/CMT# Preferred Installation: The base (20) is cooled by circulating a coolant through a coiled tube (26) running through the base. The windings of the induction coil (23) correspond to those of the coiled tube. The protective shield (30) comprises a concave bed of refractory powder. The bed can also contain carbon. The installation includes a plasma torch (35) directed towards the free surface of the silicon charge. The crucible has a metal side wall (10) with an internal cavity (12) through which coolant is passed.