Process for recovering organic acids from bleaching liquors
First Claim
1. A process for treating bleaching liquors from pulping processes based on organic acids, the process comprising cooking with organic acids and bleaching of pulp, and further comprising(a) adding inorganic acid selected from nitric acid, phosphoric acid and/or sulphuric acid to bleaching liquor obtained as a result of bleaching or a stage closely associated with bleaching;
- (b) separating the organic acids from the bleaching liquor and recycling the same to cooking to be used as cooking chemicals; and
(c) recovering the nitrogen-, phosphor- and/or sulphur-containing product thus obtained, from which organic acids have been separated, to be used as a fertilizer or as raw material for a fertilizer.
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Abstract
The invention relates to a process for treating bleaching liquors from pulping processes based on organic acids. The process is characterized in that inorganic acid, such as nitric acid, phosphoric acid and/or sulphuric acid, is added into a bleaching liquor obtained from the bleaching or a stage closely associated with bleaching, whereby organic acids contained in the bleaching liquor are released into the bleaching liquor. The organic acids are then separated from the bleaching liquor and recycled to the cooking stage to be used as cooking chemicals. The nitrogen-, phosphor- and/or sulphur-containing product thereby produced, from which organic acids have been separated, is recovered to be used as a fertilizer or as raw material for a fertilizer.
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Citations
20 Claims
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1. A process for treating bleaching liquors from pulping processes based on organic acids, the process comprising cooking with organic acids and bleaching of pulp, and further comprising
(a) adding inorganic acid selected from nitric acid, phosphoric acid and/or sulphuric acid to bleaching liquor obtained as a result of bleaching or a stage closely associated with bleaching; -
(b) separating the organic acids from the bleaching liquor and recycling the same to cooking to be used as cooking chemicals; and
(c) recovering the nitrogen-, phosphor- and/or sulphur-containing product thus obtained, from which organic acids have been separated, to be used as a fertilizer or as raw material for a fertilizer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification