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US 6,554,958 B1Granted
Process for the delignification and bleaching of chemical paper pulps with hydrogen peroxide and at least one polymer
AssigneeAtofina
InventorMichel Devic
Life of this patent
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Abstract
A process for the delignification and bleaching of chemical paper pulps comprising one or more stage(s) of treatment with hydrogen peroxide, at a temperature greater than 100° C. and under high pressure, in the presence of a polymer and of a compound A chosen from potassium hydroxide, sodium hydroxide and alkali metal or alkaline-earth metal carbonates.
Claims22
A process for the delignification and bleaching of a chemical pulp consisting of a plurality of stages, comprising:
- (1) contacting the pulp with a complexing or sequestering agent for transition metals in a pretreatment stage;
- and (2) treating the pulp with hydrogen peroxide in at least one stage at a temperature T greater than 100° C., at a pressure greater than 1.5 times the saturated vapor pressure of water at the temperature T, in the presence of (a) at least one polymer comprising units selected from the group consisting of formula (I), formula (II) and mixtures of formula (I) and formula(II):
- in which R1 and R2, which are identical or different, each independently represent a hydrogen atom or an alkyl group comprising from 1 to 3 carbon atoms and in which M is selected from the group consisting of a hydrogen atom, an ammonium group, an alkali metal, an alkaline-earth metal, and mixtures thereof, and in the presence of (b) a compound A chosen from the group consisting of potassium hydroxide, sodium hydroxide, an alkali metal carbonate, alkaline-earth metal carbonate and mixtures thereof.
A process for the delignification and bleaching of a chemical pulp consisting of a plurality of stages, comprising:
- (1) bringing the pulp into contact with a complexing or sequestering agent for transition metals in a pretreatment stage;
- and (2) subjecting the pulp to treatment with hydrogen peroxide in at least one stage at a temperature T greater than 100° C., at a pressure greater than 1.5 times the saturated vapor pressure of water at the temperature T, in the presence of (a) at least one polymer comprising units selected from the group consisting of formula (I), formula (II) and mixtures of formula (I) and formula (II):
- in which R1 and R2, which are identical or different, each independently represent a hydrogen atom or an alkyl group comprising from 1 to 3 carbon atoms and in which M is selected from the group consisting of a hydrogen atom, an ammonium group, an alkali metal, an alkaline-earth metal, and mixtures thereof, and in the presence of (b) a compound A chosen from the group consisting of potassium hydroxide, sodium hydroxide, an alkali metal carbonate, an alkaline-earth metal-carbonate and mixtures thereof;
- (3) washing the pulp with water on completion of the final treatment with hydrogen peroxide;
- and (4) incinerating the wash water.
2 more elements
Dependencies are inferred from the claim text.