Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C11/00—Regeneration of pulp liquors or effluent waste waters
  • D21C11/0021—Introduction of various effluents, e.g. waste waters, into the pulping, recovery and regeneration cycle (closed-cycle)
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
  • D21C3/06—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides sulfur dioxide; sulfurous acid; bisulfites sulfites

Definitions

• the proposed invention deals with pulp and paper production, in particular, with the process for preparing pulp cooking liquors to manufacture a fibrous semifabricate.
• a method for preparing a pulp cooking liquor by adding a sulfate into a water medium is known (1).
• the closest to the proposed invention is a well known method for preparing a cooking liquor to manufacture a fibrous semifabricate.
• the method in question requires waste water that has been treated biologically be used as a water medium.
• This waste water that normally contains an excessed activated sludge in the range of 0,5 - 17,0 g/l is to be withdrawn from a secondary thickener to dissolve sulfates.
• sulfite or bisulfite cooking methods are used the abovementioned water medium is to be saturated with sulfurous anhydride until the required pH value is reached (4).
• This method may offer cost advantages resulting from replacement fresh water with waste one after biological treatment thereof.
• this method leads to a comparatively low pulp yield and doesn't secure that the required level of its quality parameters needed now will be reached.
• waste water at low activated sludge concentration is used as a water medium here.
• the proposed invention is aimed at creating a method for preparing a pulp cooking liquor to manufacture a fibrous semifabricate in a way that makes it possible to increase the yield of the final product, improve its quality as well as to extend a stock of row materials needed for preparing sulfite cooking liquors.
• soda ash (1,5 - 2,50 % by weight based on Na 2 O) in form of a solution in biologically treated effluents of pulp and paper manufacture which in turn run between 18 and 40 g/l suspended solids or alkaline hydrolizate generated at the treatment of the same effluents by a mixture of basic salts (both Na 2 CO 3 - 50 - 90 % by weight and CaO - 1,5 - 2,5 % by weight based on Na 2 O) at the temperature of 25 - 40°C accompanied by removal of resulting precipitate are used as water medium while saturating thereof with sulfurous anhydride at 35-40°C until its content in the cooking liquor is 2,2-5,5 % by weight based on the total mass of the solution.
• basic salts both Na 2 CO 3 - 50 - 90 % by weight and CaO - 1,5 - 2,5 % by weight based on Na 2 O
• the proposed method differs from the well known one by the following features: soda ash (1,5 - 2,50 % by weight based on Na 2 O) in form of a solution in biologically treated effluents of pulp and paper manufacture running between 18 and 40 g/l suspended solids or alkaline hydrolizate generated at the treatment of the same effluents by a mixture of basic salts (Na 2 CO 3 - 50 - 90% by weight and CaO - 1,5 - 2,5 % by weight based on Na 2 O) at 25 - 40°C accompanied by removal of resulting precipitate are used as a water medium.
• the proposed method means the use of industrial waste water after biological treatment with concentration of activated sludge biomass in the range of 18 - 40g/l.
• concentration of activated sludge biomass in the range of 18 - 40g/l.
• concentration obtained by preliminary consolidation of activated sludge biomass in special settlers is optimal since it mantains higher than usual content of acid and alkali hydrolysis products in a cooking liquor that are formed during its preparation and thus, as it has been mentioned, making cooking more effective.
• the usage of industrial waste water with high concentration of activated sludge (18-40g/l) allows to utilize activated sludge biomass.
• alkali hydrolyzate as a water medium allows to get rid effectively (by means of co-precipitation with calcium carbonate) from a non-hydrolized part of activated sludge biomass, which makes up to 17% by weight based on absolutely dry substance thus improving the quality characteristics required for a fibrous semi-fabricate.
• the proposed conditions for alkali hydrolizate production (treatment by mixed base salts containing 50-90% of sodium carbonate by weight and 10-15% of calcium oxide by weght in amount of 1,55-2,50% by weight based on Na 2 O at the temperature 25-40°C followed up with removal of sediment) makes it possible to reach a complete alkali hydrolysis of bio-organic part of activated sludge and to remove an insoluble slime. All this in turn, increases the efficiency of cooking process and makes the quality of the fibrous semi-fabricate better.
• the method is carried out in the following way:
• Sodium carbonate (in amount that makes its concentration in solution equal to 1,55-2,50% by weight based on Na 2 O) is added to biologically treated waste water of a pulp and paper mill after settling thereof in a radial or vertical thickener until the activated sludge concentration in it has reached the level of 18-40g/l.
• the resultant soda ash solution is sent to an absorber for saturation with sulfurous anhidride at the temperature 35-45°C until its concentration is of 2,5-5,5% by weight and organic part of the sludge is dissolved.
• a pulp and paper mill waste water that has been treated biologically and then stored in a thickener until the excessed activated sludge concentration in it has reached the level of 18-40g/l is delivered to a mixer to be treated with a mixed base salts in amount of 1,55-2,50% by weight based on Na 2 O at the temperature of 25-40°C provided that it is accompanied by thorough mixing until the activated sludge biomass is dissolved completely.
• the resulting mixture containing alkali hydrolizate, undissolved slime and calcium carbonate is to be dewatered by filtration or precipitation.
• the resultant clarified alkali hydrolyzate is sent to an absorber for saturation with sulfurous anhydride at the temperature of 35-45°C until the concentration thereof is 2,5-5,5% by weight is reached.
• the metod is illustrated by the following examples:
• the cooking process was carried out during 2 hours 15 minutes while the temperature being raised from 25°C to 100°C; then during 45 minutes the temperature was kept at 120°C and during another 1 hour and a half it had been raising from 120°C to 160°C. Then the process proceeded at that temperature (160°C) for another 1 hour.
• the cooking is over a 75g/l sample of the resultant semifabricate was used to determine both its whiteness and mechanical characteristics. The results obtained are given in the Table.
• the cooking liquor was prepared in the following way: The waste water from a pulp and paper mill with activated sludge making up 30g/l in it was treated by a mixed base containing the equal parts of sodium carbonate and calcium oxide in amount of 2,5% by weight based on Na 2 O at the temperatute 35°C. After the sediment had been removed the alkali hydrolyzate was saturated with sulfurous anhydride at the temperature 40°C until the concentration thereof was reached 5,5% by weight. The resultant cooking liquor with products yielded by the alkali hydrolysis of activated sludge had 1,9 pH value. The cooking process was carried out under the same conditions as it was in the Example 1. The results are given in the Table.
• the cooking process is held in conditions of Example 1.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)
• Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=20173977

Family Applications (1)

Country Status (10)

Families Citing this family (1)

Family Cites Families (13)

• 1995
  • 1995-11-21 RU RU9595119640A patent/RU2091529C1/ru active
• 1996
  • 1996-11-13 BR BR9611644A patent/BR9611644A/pt not_active Application Discontinuation
  • 1996-11-13 KR KR1019980703770A patent/KR19990071498A/ko not_active Withdrawn
  • 1996-11-13 CA CA002238100A patent/CA2238100A1/fr not_active Abandoned
  • 1996-11-13 JP JP9519633A patent/JP2000500538A/ja not_active Abandoned
  • 1996-11-13 AU AU77137/96A patent/AU7713796A/en not_active Abandoned
  • 1996-11-13 WO PCT/RU1996/000323 patent/WO1997019220A2/fr not_active Ceased
  • 1996-11-13 EP EP96940192A patent/EP0863250A4/fr not_active Withdrawn
  • 1996-11-13 CN CN96199607A patent/CN1207782A/zh active Pending
• 1998
  • 1998-05-20 NO NO982293A patent/NO982293L/no unknown

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