Preparation of detergent grade sodium tripolyphosphate from wet process phosphoric acid and soda ash
AssigneeStauffer Chemical Company
InventorsMazin R. Irani, Kirk V. Darragh
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Abstract
A process for preparing detergent grade sodium tripolyphosphate from wet process phosphoric acid comprising neutralizing said acid to a pH at which the Na:P ratio is about 5:3, contacting the resultant mixture of mono- and disodium orthophosphates with an oxidizing agent selected from the group consisting of ozone, hydrogen peroxide and mixtures thereof, in amounts sufficient to oxidize color causing impurities, and drying and heating said orthophosphates to effect the change to sodium tripolyphosphate.
Claims6
A process for the preparation of sodium tripolyphosphate from wet process phosphoric acid containing color causing impurities which comprises sequentially performing the steps of:
- (a) neutralizing said wet process phosphoric acid within the pH range from about 6 to about 8 with an alkali selected from the group consisting of soda ash, sodium hydroxide, sodium bicarbonate, sodium sesquicarbonate, and mixtures thereof to form a solution of mixtures of mono- and disodium orthophosphates containing organic or inorganic precipitate;
- (b) contacting said solution containing organic or inorganic precipitate with an oxidizing agent selected from the group consisting of ozone, hydrogen peroxide, and mixtures thereof in an amount sufficient to oxidize and precipitate color causing impurities;
- (c) separating the precipitated color causing impurities of step (b) from said solution of mixtures of orthophosphates;
- and
- (d) drying and heating said solution of mixtures of orthophosphates to effect the change to sodium tripolyphosphate.
Dependencies are inferred from the claim text.