Process and apparatus for treating exhausted abrasive slurries for the recovery of their reusable components
AssigneeSic Processing AG
InventorGuido Fragiacomo
Life of this patent
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Abstract
Process and apparatus for completely recovering the reusable components of an abrasive slurry used in slicing crystalline materials of silicon, quartz or ceramics when it becomes exhausted and enriched with undesired waste matter. The process consists of an initial centrifuge separation of the exhausted slurry as such and of a wet size-sorting treatment of the fraction containing the abrasive grains obtained from the centrifuge, carried out in a battery of hydrocyclones or centrifuges connected in series. The section for the recovery and purification of the abrasive grains comprises a multifunctional apparatus that performs all the required operations within a single pressure vessel.
Claims26
An apparatus for treating exhausted abrasive slurries including a suspending liquid, reusable abrasive grains, fine abrasive grains, fine silicon particles and fine metal particles, including the following interconnected elements:
- a first centrifuge, comprising an underflow and an overflow,
- a battery of separators in series, wherein the battery of separators comprises at least two separators including a first separator and a second separator, wherein an underflow of the first separator is fed to the second separator and an overflow of the second separator in the series is fed to the first separator, and wherein the separators are either hydrocyclones or centrifuges each including an underflow, an overflow, and an inlet;
- a filter including a liquid outlet,
- a multifunctional apparatus adapted to perform the following steps A)-D) without any transfer of material:
- A) filtering a liquid suspension to obtain a solid fraction,
- B) washing the solid fraction to obtain a washed solid fraction,
- C) leaching from the washed solid fraction, by chemical etching, any fine silicon particles and fine metal particles to obtain a washed and leached solid fraction, and,
- D) drying the washed and leached solid fraction to obtain dry abrasive grains, wherein the multifunctional apparatus includes an inlet;
- a treatment section for recovering suspension liquid, the treatment section comprising means for solid-liquid separation treatments and means for liquid-solvent distillation;
- wherein the underflow of the first centrifuge is connected to the inlet of the first separator of the battery, the overflow of the first centrifuge is connected to the treatment section, the overflow of the first separator is connected to the filter, the liquid outlet of the filter is connected to the inlet of the final separator of the battery and to the treatment section, and the underflow of the final separator of the battery is connected to the inlet of the multifunctional apparatus.
A process for treating an exhausted abrasive slurry including a suspending liquid, reusable abrasive grains, fine abrasive grains, fine silicon particles and fine metal particles, comprising the following steps:
- separating the exhausted abrasive slurry by wet size-sorting treatment in a centrifuge into
- a first liquid suspension containing part of the suspending liquid and the reusable abrasive grains, and
- a second liquid suspension containing the remaining part of the suspending liquid and the fine abrasive grains as well as the fine silicon particles and fine metal particles;
- providing a battery of separators in series, wherein the battery of separators comprises at least two separators including a first separator and a second separator, wherein an underflow of the first separator is fed to the second separator and an overflow of the second separator in the series is fed to the first separator, and wherein the separators are either hydrocyclones or centrifuges,
- the first liquid suspension is fed to the first separator of the battery,
- a third liquid suspension is obtained from an overflow of the first separator of the battery,
- subjecting the third liquid suspension to filtration to obtain a fourth liquid suspension and joining a first portion of the fourth liquid suspension to the second liquid suspension to provide a fifth liquid suspension;
- adding a solvent to the remaining portion of the fourth liquid suspension to obtain a liquid and feeding the liquid to the final separator of the battery,
- obtaining a sixth liquid suspension from an underflow of the final separator of the battery, wherein the sixth liquid suspension contains the reusable abrasive grains and is substantially free from fine abrasive grains,
- further treating the sixth liquid suspension in a multifunctional apparatus implementing the following consecutive steps A)-D) without any transfer of material:
- A) filtering the sixth liquid suspension to obtain a solid fraction,
- B) washing the solid fraction to obtain a washed solid fraction,
- C) leaching from the washed solid fraction, by chemical etching, any fine silicon particles and fine metal particles to obtain a washed and leached solid fraction, and,
- D) drying the washed and leeched solid fraction to obtain dry abrasive grains,
- and recovering the suspending liquid from the fifth liquid suspension by means of solid-liquid separation treatments combined with liquid-solvent distillation.
Dependencies are inferred from the claim text.