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US 7,029,554 B2Granted
Method for brightening pulp with hydrosulfite solution generated from borohydride and bisulfite
AssigneeRohm and Haas Company
InventorRangamannar Goda
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Abstract
A method for brightening pulp at a pH from 4.5 to 9. The method comprises the steps of: (a) combining an alkali metal borohydride, an alkali metal hydroxide, an alkali metal bisulfite and phosphoric acid to form a reducing solution; and (b) adding the reducing solution to a pulp slurry in an amount from 0.1% to 4% of hydrosulfite based on dry pulp fiber.
Claims11
A method for brightening pulp at a pH from 4.5 to 9;
- said method comprising steps of:
- (a) combining an alkali metal borohydride, an alkali metal hydroxide, an alkali metal bisulfite and phosphoric acid to form a reducing solution which comprises hydrosulfite;
- and
- (b) adding the reducing solution to a pulp slurry in an amount from 0.1% to 4% of hydrosulfite based on dry pulp fiber;
- wherein the alkali metal hydroxide is added in an amount from 1 kg to 10 kg, the alkali metal bisulfite is added in an amount from 10 kg to 30 kg, and phosphoric acid is added in an amount from 1 kg to 30 kg, all on a basis of 1 kg of alkali metal borohydride.
2 more elements
Dependencies are inferred from the claim text.