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US 8,505,733 B2Granted
Methods to slice a silicon ingot
AssigneeMEMC Singapore Pte. Ltd.
InventorsAlexis Grabbe, Tracy M. Ragan
Life of this patent
Estimating the term…
Abstract
The present disclosure generally relates to methods for recovering silicon from saw kerf, or an exhausted abrasive slurry, resulting from the cutting of a silicon ingot, such as a single crystal or polycrystalline silicon ingot. More particularly, the present disclosure relates to methods for isolating and purifying silicon from saw kerf or the exhausted slurry, such that the resulting silicon may be used as a raw material, such as a solar grade silicon raw material.
Claims15
A method for slicing a silicon ingot, the method comprising
- contacting a surface of the silicon ingot with a reciprocating wire saw and a slurry comprising an organic lubricating fluid, an abrasive particulate, and a metal chelating agent soluble in the organic lubricating fluid,
- wherein said contact of the surface of the silicon ingot with the reciprocating wire saw cause silicon particles from the ingot to be removed and form part of the slurry, the method further comprising:
- mixing the slurry with an aqueous acid solution and allowing the mixture to separate into an aqueous phase and an organic phase, the aqueous phase comprising silicon particles and abrasive particulate and the organic phase comprising a complex formed between the chelating agent and metals;
- collecting the aqueous phase comprising the silicon particles and the abrasive particulate;
- and
- contacting aqueous phase comprising the silicon particles and the abrasive particulate with a source of iodine, in order to convert at least a portion of the silicon present therein to SiI4;
- and
- recovering at least a portion of the silicon particles from the aqueous phase by subjecting the aqueous phase to a density-dependent separation technique to separate the silicon particles and SiI4 from the abrasive particulate, wherein the density-dependent separation technique is selected from sedimentation centrifugation, filtration centrifugation, and hydro-cyclone separation.
5 more elements
A method for slicing a silicon ingot, the method comprising
- contacting a surface of the silicon ingot with a reciprocating wire saw and a slurry comprising an organic lubricating fluid, an abrasive particulate, and a metal chelating agent soluble in the organic lubricating fluid,
- wherein said contact of the surface of the silicon ingot with the reciprocating wire saw cause silicon particles from the ingot to be removed and form part of the slurry, the method further comprising:
- mixing the slurry with an aqueous acid solution and allowing the mixture to separate into an aqueous phase and an organic phase, the aqueous phase comprising silicon particles and abrasive particulate and the organic phase comprising a complex formed between the chelating agent and metals;
- collecting the aqueous phase comprising the silicon particles and the abrasive particulate;
- drying the collected aqueous phase to thereby form a dry mixture comprising the silicon particles and the abrasive particulate;
- separating at least a portion of the silicon particles from the abrasive particulate by subjecting the dried mixture to a non-uniform magnetic field.
3 more elements
Dependencies are inferred from the claim text.