Process and apparatus for obtaining silicon from fluosilicic acid

Patent · 16 July 1985

OSTI ID:865515

Sancier, Kenneth M ^[1]

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1. Menlo Park, CA

Process for producing low cost, high purity solar grade Si wherein a reduction reaction, preferably the reduction of SiF.sub.4, by an alkali metal (liquid Na preferred) is carried out essentialy continuously by injecting of reactants in substantially stoichiometric proportions into a reaction chamber having a controlled temperature thereby to form a mist or dispersion of reactants. The reactants being supplied at such a rate and temperature that the reaction takes place far enough away from the entry region to avoid plugging of reactants at the entry region, the reaction is completed and whereby essentially all reaction product solidifies and forms a free flowing powder before reaction product hits a reaction chamber wall. Thus, the reaction product does not adhere to the reaction chamber wall or pick up impurities therefrom. Separation of reaction products is easily carried out by either a leach or melt separation process.

• Assignee: SRI International (Menlo Park, CA)
• Patent Number(s): US 4529576
• Application Number: 06/453,457
• OSTI ID: 865515
• Country of Publication: United States
• Language: English

Related Subjects

/423/136/422/
acid
adhere
alkali
alkali metal
apparatus
avoid
avoid plugging
carried
chamber
chamber wall
completed
continuously
controlled
controlled temperature
cost
dispersion
easily
entry
entry region
essentially
essentialy
flowing
fluosilicic
fluosilicic acid
form
forms
free
free flow
free flowing
grade
hits
impurities
impurities therefrom
injecting
leach
liquid
liquid na
melt
melt separation
metal
mist
na
na preferred
obtaining
obtaining silicon
pick
plugging
powder
preferably
preferred
process
producing
product
products
proportions
purity
purity solar
rate
reactants
reaction
reaction chamber
reaction product
reaction products
reaction takes
reduction
reduction reaction
region
separation
separation process
sif
silicic acid
silicon
solar
solar grade
solidifies
stoichiometric
substantially
supplied
takes
temperature
therefrom
wall
whereby