Method of treating silica fumes for whitening purposes
AssigneeElectricite de France (Service National)
InventorFrancois Baudequin
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Abstract
The black powder to be treated is injected into the bottom portion of a heated dense fluidized bed, said bed having effective depth enabling the carbon the particles of silica to be oxidized into carbon dioxide as the particles go through the dense fluidized bed while being entrained by the fluidization air. The whitened powder is then recovered by filtering the gases leaving said dense fluidized bed. The invention is particularly applicable to the cosmetics industry for producing make-up that uses silica powder.
Claims13
A method for treating blackened silica fumes for whitening purposes, where said blackened silica fumes comprise a plurality of silica particles coated with carbon, said method comprising the steps of:
- injecting said blackened silica fumes having a diameter less than one micrometer into a heated dense fluidized bed including a plurality of sand particles, said dense bed having a depth determines by a means grain size of said plurality of silica particles;
- oxidizing the carbon with fluidization air while the silica fumes pass through the dense fluidized bed;
- and
- recovering said plurality of silica particles having said diameter less than one micrometer which have passed through said dense fluidized bed.
A method for treating blackened silica fumes for whitening purposes, where said blackened silica fumes comprise a plurality of silica particles coated with carbon, said method comprising the steps of:
- injecting said blackened silica fumes having a diameter less than one micrometer into a dense fluidized bed, said fluidized bed including a plurality of sand particles, wherein each of said plurality of sand particles having a diameter greater than 30 micrometers;
- oxidizing the carbon with fluidization air while the silica fumes pass through the dense fluidized bed having a depth determinable by a mean grain size of said plurality of silica particles;
- recovering said plurality of silica particles having said diameter less than one micrometer which have passed through said fluidized bed.
A method for treating blackened silica fumes for whitening purposes, where said blackened silica fumes comprise a plurality of silica particles coated with carbon, said method comprising the steps of:
- injecting said blackened silica fumes having a diameter less than one micrometer into a dense fluidized bed, said fluidized bed including a plurality of sand particles, wherein each of said plurality of sand particles having a means grain size of approximately 400 micrometers;
- oxidizing the carbon with fluidization air while the silica fumes pass through the dense fluidized bed having a depth of 1.5 meters, said depth being a function of said means grain size of said plurality of sand particles;
- and
- recovering said plurality of silica particles having such a diameter less than one micrometer which said dense fluidized bed through filtration.
Dependencies are inferred from the claim text.