Recovery of silicon value from kerf silicon waste
AssigneeSemlux Technologies, Inc.
InventorsAlleppey V. HARIHARAN, Jagannathan RAVI
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Abstract
The present invention is for the recovery of maximum silicon value of kerf silicon waste, produced during the manufacture of silicon wafers by wire saw, diamond saw and chemical mechanical polishing, as high purity metallurgical silicon. This recovery is achieved by a process scheme that effects an initial removal of minor extrinsic metallic impurities but not the major silicon compound impurities, and followed, preferentially, by a direct metallurgical process to form elemental silicon. The recovered silicon is for use as feedstock for polysilicon manufacturing, as high purity polysilicon for PV application, and in metallurgical alloy manufacture.
Claims13
A process methodology to recover silicon values of kerf silicon waste that converts kerf silicon waste originating from wire saw process to high purity silicon by a sequential process comprising:
- a. providing a kerf silicon waste;
- b. providing a pretreatment to the kerf silicon waste;
- c. providing a composition adjustment to the pretreated kerf silicon waste to produce a kerf material mixture;
- d. converting the kerf material mixture to silicon product and
- e. refining the silicon product to a higher purity level.
The method according to claim 1, wherein the conversion of kerf material mixture to silicon is carried out through a process that comprises to melt the silicon and to cause chemical reduction of the silicon oxide by the wire saw abrasive material to form silicon and thereby efficiently consume the wire saw abrasive material in the kerf material mixture and recover the full and complete silicon value present in the kerf silicon waste and introduced silicon oxide. The method according to claim 6, wherein the conversion process is performed in an electric arc furnace.
Dependencies are inferred from the claim text.