Process and apparatus for obtaining silicon from fluosilicic acid

Patent · Tue May 31 00:00:00 EDT 1988

OSTI ID:6910629

Nanis, L; Sanjurjo, A

This patent describes a process for producing 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 by melt separation and wherein the 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. The process comprises: carrying out the reaction inside a graphite reaction chamber formed with at least one bottom drainage port therethrough, the port being of sufficient size so that essentially all reaction product other than silicon freely flow through and silicon is preferentially contained, the flow being due to the low surface tension of the other reaction products as compared to that of silicon.

• Assignee: SRI International, Menlo Park, CA
• Patent Number(s): US 4748014
• OSTI ID: 6910629
• Resource Relation: Patent File Date: Filed date 26 Nov 1985
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
09 BIOMASS FUELS
CHEMICAL REACTORS
FLUORINE COMPOUNDS
PROCESSING
SILICIC ACID
SILICON
PRODUCTION
AQUEOUS SOLUTIONS
CHEMICAL REACTION YIELD
GRAPHITE
MELTING
PHOSPHATE ROCKS
SILICON FLUORIDES
SILICON SOLAR CELLS
SODIUM
SODIUM SILICATES
STOICHIOMETRY
THERMAL DEGRADATION
ALKALI METAL COMPOUNDS
ALKALI METALS
CARBON
DIRECT ENERGY CONVERTERS
DISPERSIONS
ELEMENTAL MINERALS
ELEMENTS
EQUIPMENT
FLUORIDES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
METALS
MINERALS
MIXTURES
NONMETALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
ROCKS
SEDIMENTARY ROCKS
SEMIMETALS
SILICATES
SILICON COMPOUNDS
SODIUM COMPOUNDS
SOLAR CELLS
SOLAR EQUIPMENT
SOLUTIONS
YIELDS
360601* - Other Materials- Preparation & Manufacture
400201 - Chemical & Physicochemical Properties
140504 - Solar Energy Conversion- Biomass Production & Conversion- (-1989)