Apparatus for obtaining silicon from fluosilicic acid
AssigneeSRI International
InventorAngel Sanjurjo
Life of this patent
Estimating the term…
Abstract
Apparatus for producing low cost, high purity solar grade silicon ingots in single crystal or quasi single crystal ingot form in a substantially continuous operation in a two stage reactor starting with sodium fluosilicate and a metal more electropositive than silicon (preferably sodium) in separate compartments having easy vapor transport therebetween and thermally decomposing the sodium fluosilicate to cause formation of substantially pure silicon and a metal fluoride which may be continuously separated in the melt and silicon may be directly and continuously cast from the melt.
Claims13
A system for producing low cost, high purity, solar grade silicon by reaction of gaseous silicon tetrafluoride with sodium in substantially stoichiometric quantities to produce a reaction product from which silicon is recovered and wherein said fluoride gas used in the reaction is obtained by thermal decomposition of sodium fluosilicate which is precipitated from aqueous fluosilicic acid generated from phosphate rock conversion to fertilizer, said system including:
- a chemical reactant feed section and a reactor section;
- said reactor section including first and second reactant receiving compartments having a common wall with passages therethrough of a size to allow easy vapor transport;
- said chemical feed section having first reactant delivery means to introduce a first reactant into said first reactant receiving compartment and a second reactant delivery means to deliver a second reactant into said second reactant receiving compartment;
- and means to decompose reactant delivered to said second reactant receiving compartment thereby to generate a vapor phase reactant and cause vapor transport between said second and first reactant receiving compartments whereby reaction between said vapor phase reactant and reactant delivered to said first reactant receiving compartment reacts to produce reaction products including silicon, said reaction products being directed into a reaction product receiving and melt separation compartment having heating means surrounding said reaction product receiving and melt separation compartment so as to maintain said reaction products in the melt and facilitate separation of said reaction products.
A system for producing low cost, high purity, solar grade silicon by reaction of gaseous silicon tetrafluoride with sodium in substantially stoichiometric quantities to produce a reaction product from which silicon is recovered and wherein said fluoride gas used in the reaction is obtained by thermal decomposition of sodium fluosilicate which is precipitated from aqueous fluosilicic acid generated from phosphate rock conversion to fertilizer, said system including:
- a chemical reactant feed section and a reactor section;
- said reactor section including first and second reactant receiving compartments and third and fourth reaction product receiving compartments;
- said first and second reactant receiving compartments having a common wall with passages therethrough of a size to allow easy vapor transport therethrough;
- said chemical feed section having first reactant delivery means to introduce a first reactant into said first reactant receiving compartment and a second reactant delivery means to deliver a second reactant into said second reactant receiving compartment;
- means to decompose reactant delivered to said second reactant receiving compartment thereby to generate a vapor phase reactant and cause vapor transport between said second and first reactant receiving compartments whereby reaction between said vapor phase reactant and reactant delivered to said first reactant receiving compartment takes place to produce reaction products;
- said third reaction product receiving compartment disposed to receive reaction products from said first and said second reactant receiving compartments and having walls formed with passages therethrough, said passages being of a size such that essentially all molten reaction products other than silicon freely pass through and molten silicon is preferentially retained;
- said third compartment having heating means surrounding said reaction product receiving and melt separation compartment so as to maintain said reaction products in the melt and facilitate separation of said reaction products;
- said fourth reaction product receiving compartment substantially surrounding said third reactant receiving compartment and separated therefrom by said wall of said third reactant receiving chamber having passages therethrough thereby to collect said reaction product passing through said passages;
- said fourth reactant receiving compartment having an outlet thereby to constitute a reaction product collection and dispensing means;
- and said third reaction product compartment having an outlet for removing the reaction product remaining therein by free flow.
Dependencies are inferred from the claim text.