Process for purifying water containing fluoride ion
AssigneeAndco Industries, Inc.
InventorStanley Bruckenstein
Life of this patent
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Abstract
A process for purifying water containing fluoride which comprises precipitating fluoride from the water as fluorapatite in the presence of a bed of seeding composition. Fluoride is removed as fluorapatite by having sufficient available calcium for each mole of fluoride present in the water and sufficient available phosphate for each mole of fluoride in the water to form a precipitate which is or converts to sufficient fluorapatite to remove essentially all fluoride from the water.
Claims25
A continuous process for purifying water containing fluoride which comprises:
- (a) continuously adding sufficient calcium composition to a stream of water to provide at least five moles of available calcium in said water for each mole of fluoride in said water;
- (b) continuously adding sufficient phosphate composition to said stream;
- and
- (c) making any adjustment in the pH of said water which is required to provide a desired pH in the water of from 6.0 to about 11.5;
- and
- (d) causing said stream to pass through a bed of a particulate seeding composition selected from the group consisting of fluorapatite, calcium fluoride and mixtures thereof, the residence time of said stream through said bed being sufficient to permit a precipitate to form which contains essentially all fluoride which was present in the water.
A continuous process for purifying water containing fluoride and at least five moles of available calcium for each mole of fluoride to be removed which comprises:
- (a) continuously adding sufficient phosphate composition to a stream of said water to provide sufficient available phosphate in said water;
- (b) adding from 0 to about 5 weight percent of an acid or base to said water to obtain a desired pH of from about 6.0 to about 11.5;
- and
- (c) causing said stream to pass through a bed of a particulate seeding composition selected from the group consisting of fluorapatite, calcium fluoride and mixtures thereof, the residence time of said stream through said bed being sufficient to permit a precipitate to form which contains essentially all fluoride which was present in the water.
Dependencies are inferred from the claim text.