System and method for manufacturing high purity silicon

Abstract

A system and a method for producing silicon from a SiO2-containing material that includes solid SiO2. The method uses a reaction vessel including a first section and a second section in fluid communication with said first section. The method includes: heating the SiO2-containing material that includes the solid SiO2 to a SiO2-containing material that includes liquid SiO2, at a sufficient temperature to convert the solid SiO2 into the liquid SiO2; converting, in the first section, the liquid SiO2 into gaseous SiO2 that flows to the second section by reducing the pressure in the reaction vessel to a subatmospheric pressure; and reducing, in the second section, the gaseous SiO2 into liquid silicon using a reducing gas. The reducing of the pressure is performed over a continuous range of interim pressure(s) sufficient to evaporate contaminants from the SiO2-containing material, and removing by vacuum, the one or more evaporated gaseous contaminants.

1 .- 40 . (canceled) 
     
     
         41 . A system for producing silicon from a silicon dioxide (SiO 2 )-containing material that includes solid SiO 2 , the system comprising:
 a heat source for heating the SiO 2 -containing material that includes solid SiO 2  to a SiO 2 -containing material that includes liquid SiO 2 , at a sufficient temperature to convert the solid SiO 2  into the liquid SiO 2 ;   a reaction vessel comprising a first section and a second section in fluid communication with said first section, said first section for containing the SiO 2 -containing material that includes liquid SiO 2 ;   a vacuum source for reducing the pressure to a subatmospheric pressure for converting, in the first section, the liquid SiO 2  into gaseous SiO 2  that flows to the second section;   wherein the second section is for reducing of the gaseous SiO 2  into liquid silicon in the second section.   
     
     
         42 . The system of  claim 41  further comprising at least one gas inlet to facilitate the reducing of the gaseous SiO 2  into the liquid silicon in the second section by introducing an amount of a process gas. 
     
     
         43 . The system of  claim 42  wherein the amount of the process gas is about 7 times stoichiometric value or more. 
     
     
         44 . The system of  claim 42  wherein the at least one gas inlet is configured to introduce the process gas into a region where the gaseous SiO 2  enters the second section. 
     
     
         45 . The system of  claim 41  wherein the vacuum source is configured to reduce the pressure to the subatmospheric pressure over a continuous range of one or more interim pressures sufficient to evaporate one or more contaminants from the SiO 2 -containing material that contains the liquid SiO 2  to one or more gaseous contaminants, prior to the pressure reaching the subatmospheric pressure that converts the liquid SiO 2  into the gaseous SiO 2 . 
     
     
         46 . The system of  claim 45  further comprising at least one gas outlet to remove the one or more gaseous contaminants evaporated from the SiO 2 -containing material that includes the liquid SiO 2 . 
     
     
         47 . The system of  claim 46  wherein the at least one gas outlet is positioned above the first section. 
     
     
         48 . The system of  claim 46  wherein the at least one gas outlet comprises a pipe that stems from a tangential perimeter of the first section. 
     
     
         49 . The system of  claim 48  wherein the pipe penetrates through the second section. 
     
     
         50 . The system of  claim 41  wherein the second section further comprises at least one vane for inducing a circumferential flow of gases in the second section so as to allow for an amount of time to reduce the gaseous SiO 2  into liquid silicon. 
     
     
         51 . The system of  claim 50  wherein a plurality of vanes extend from the wall of the second section and are configured so as to form a helical pathway for directing flow of gases therein. 
     
     
         52 . The system of  claim 50  wherein a ratio of the vapor flow area for gases proximal the second section to the vapor flow area for gases proximal the first section is on or about 70:1. 
     
     
         53 . The system of  claim 41  wherein the first section and the second section are in a co-axial arrangement wherein the second section substantially surrounds the first section. 
     
     
         54 . The system of  claim 53  wherein the heat source comprises a heat recuperation chamber configured between the first section and the second section, wherein the heat recuperation chamber allows heat produced in the second section to be directed towards the first section. 
     
     
         55 . The system of  claim 54  wherein the heat recuperation chamber further comprises at least one vane for inducing a circumferential flow of gases in the heat recuperation chamber so as to allow for an amount of time to reduce the gaseous SiO 2  into liquid silicon. 
     
     
         56 . The system of  claim 55  wherein a plurality of vanes extend from the wall of the heat recuperation chamber and are configured so as to form a helical pathway for the movement of gases therein. 
     
     
         57 . The system of  claim 41  wherein the first section is positioned over a part of the second section. 
     
     
         58 . The system of  claim 57  further comprising one or more channels formed in a wall between the first section and the second section, the one or more channels dimensioned to allow the gaseous SiO 2  formed in the first section to move into the second section. 
     
     
         59 . The system of  claim 58  wherein the one or more channels have an interior diameter which increases in the direction moving towards the second section from the first section such that a vapor flow area for gases proximal the second section is greater than a vapor flow area for gas proximal the first section in order to accommodate expansion of the gases moving from the first section to the second section through the one or more channels. 
     
     
         60 . The system of  claim 57  further comprising a channel formed in a wall between the first section and the second section, the channel is dimensioned to allow the gaseous SiO 2  formed in the first section to move into the second section. 
     
     
         61 . The system of  claim 60  wherein the channel is an annular channel configured to allow unobstructed outward radial flow of gaseous SiO 2  from the first section to the second section. 
     
     
         62 . The system of  claim 61  wherein the wall comprises a first section facing side and a second section facing side, the second section facing side including a slope, wherein the annular channel has an interior diameter which increases in the direction moving from the first section facing side to the second section facing side such that a vapor flow area for gases proximal the second section is greater than a vapor flow area for gas proximal the first section in order to accommodate expansion of the gases moving from the first section to the second section through the annular channel. 
     
     
         63 . The system of  claim 57  wherein the at least one gas inlet comprises a gas chamber positioned above the second section, the gas chamber defining an array of holes configured to direct the process gas downwards and into the second section. 
     
     
         64 . The system of  claim 63  wherein the gas chamber is substantially circular. 
     
     
         65 . The system of  claim 57  wherein the heat source comprises a heating vessel configured to direct heat energy from a heated gas contained therein towards the first section to heat the SiO 2 -containing material in the first section. 
     
     
         66 . The system of  claim 65  wherein the heating vessel comprises:
 one or more inlets for receiving a fuel and an oxidant for a combustion reaction in the heating vessel; and 
 one or more outlets for removing combustion products from the heating vessel. 
 
     
     
         67 . The system of  claim 66  wherein the fuel is hydrogen (H 2 ) and the oxidant is air or oxygen (O 2 ). 
     
     
         68 . The system of  claim 57  further comprising an electrode for delivering an ionization current into a region where the process gas enters the second section. 
     
     
         69 . The system of  claim 41  further comprising an evaporation element to promote evaporation of contents in the first section and/or the second section. 
     
     
         70 . The system of  claim 69  wherein the evaporation element is one or more injection ports for introducing a gas directly into the contents of the first section and/or the second section. 
     
     
         71 . The system of  claim 70  wherein the gas is inert gas, carbon monoxide (CO) or hydrogen (H 2 ).