CA1172808A - Kraft overload recovery process - Google Patents
Kraft overload recovery processInfo
- Publication number
- CA1172808A CA1172808A CA000382387A CA382387A CA1172808A CA 1172808 A CA1172808 A CA 1172808A CA 000382387 A CA000382387 A CA 000382387A CA 382387 A CA382387 A CA 382387A CA 1172808 A CA1172808 A CA 1172808A
- Authority
- CA
- Canada
- Prior art keywords
- kraft
- acidified
- lignin
- rest
- recovery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- D21C11/04—Regeneration of pulp liquors or effluent waste waters of alkali lye
Landscapes
- Paper (AREA)
- Compounds Of Unknown Constitution (AREA)
Abstract
KRAFT OVERLOAD RECOVERY PROCESS
ABSTRACT
The present invention relates to a kraft overload recovery process for the treatment of kraft black liquor (b.l.) which comprises acidifying the b.1.
with an acid comprising sulfuric acid, separating the lignin therefrom, and further treating the residual b.1.
tor recovery of inorganics contained therein for use as a source of cooking chemical in kraft cooks.
ABSTRACT
The present invention relates to a kraft overload recovery process for the treatment of kraft black liquor (b.l.) which comprises acidifying the b.1.
with an acid comprising sulfuric acid, separating the lignin therefrom, and further treating the residual b.1.
tor recovery of inorganics contained therein for use as a source of cooking chemical in kraft cooks.
Description
~ Z~
Field of the Invention The present invention relates to a process for the treatment o~ kraft black liquor. More particularly the present invention relates to a process for the treat-ment of black liquor which can augment the saltcake recovery capacity of a recovery installation.
B~ k~r~nd of the Invention/Prior Art The kraft pulping of lignocellulosic material in the form of wood chips usually entails the reaction and dissolution by an alkaline li~uor (white liquor) of lignin which serves as a binder for the cellulosic mate-rial. The dissolution of this binder serves to liberate the fibres, which are separated from the residual cooking liquor, which is known in the art as blask liquor. The black liquor, which contains inorganic compounds result-ing from the cooking chemical along with the dissolved wood components i5 first concentrated by evaporation and is then fed to a recovery furnace where organic wood components are burnt with the evolution of heat, while the inorganic components are subjected to a reduction stage in ~he furnace~ q'he i~organic residue ~rom the furnace is called smelt. The smelt derived from a kraft pulping process contains soda ash (sodium carbonatej and sodium sulfideO
Rraft recovery furnaces usually represent a substantial capital investment with fixed capacity.
Accordingly, few viable options exist for pulping chemi-cals recovery for a kraft mill wishing to increase its volume of production where the recovery furnace is running at capacity.
It is therefore an ob]ect of the present inven-tion to provide a process which permits an increase in the capacity for inorganics recovery for kraft furnaces
Field of the Invention The present invention relates to a process for the treatment o~ kraft black liquor. More particularly the present invention relates to a process for the treat-ment of black liquor which can augment the saltcake recovery capacity of a recovery installation.
B~ k~r~nd of the Invention/Prior Art The kraft pulping of lignocellulosic material in the form of wood chips usually entails the reaction and dissolution by an alkaline li~uor (white liquor) of lignin which serves as a binder for the cellulosic mate-rial. The dissolution of this binder serves to liberate the fibres, which are separated from the residual cooking liquor, which is known in the art as blask liquor. The black liquor, which contains inorganic compounds result-ing from the cooking chemical along with the dissolved wood components i5 first concentrated by evaporation and is then fed to a recovery furnace where organic wood components are burnt with the evolution of heat, while the inorganic components are subjected to a reduction stage in ~he furnace~ q'he i~organic residue ~rom the furnace is called smelt. The smelt derived from a kraft pulping process contains soda ash (sodium carbonatej and sodium sulfideO
Rraft recovery furnaces usually represent a substantial capital investment with fixed capacity.
Accordingly, few viable options exist for pulping chemi-cals recovery for a kraft mill wishing to increase its volume of production where the recovery furnace is running at capacity.
It is therefore an ob]ect of the present inven-tion to provide a process which permits an increase in the capacity for inorganics recovery for kraft furnaces
- 2 -1~7'~
which are already running at capacity.
Brief Description of the Invention The presen~ invention relates to a kra~toverload recovery process for the recovery of black liquor (b.l.) resulting from a kraft pulping process in a kraft recovery system having a kraft recovery ~urnace comprising the steps of:
(a) feeding a first portion of the b.l. to said furnace, (b) acidifyin~ a second portion of said b.l.
with an acid comprising sulfuric acid so as to insolubilize substantially all the lignin contained in the second portion and form sodium sulfate, (c) separating the insoluble lignin from the rest of the acidi~ied second portion, the rest of the acidified second portion comprising organic and inorganic components, ~ d) feeding at least ~aid inorganic component, comprising the sodium sulfate to the kraft recovery system op~r~ting at capacity.
Brief Description of the ~rawings ., The single figure ~Figure 1) provides a sche-matic flow diagram of the preferred embodiment of the present invention.
Detailed Description of the Present Invention Accordingly, the present invention provides a process for treating black liquor which is a product of a kraft process for pulping lignocellulosic material. The process permits the recovery of lignin (and possibly sugar acids) and the recovery of inorganic values Erom the black liquor in excess of those recoverable by a fixed capacity kraft recovery system.
Broadly then, this process for augmenting the recovery capacity of a kraft recovery system already operating at capacity will comprise feeding a first por-tion of the b.l. to the kraft recovery system wbich is thus operating at capacity, acidifying a second portion of the b.l. with an acid containing sulfuric acid so as to insolubilize substantially all the lignin contained in the second portion and convert substantially all the sodium values therein to sodium sulfate. This insoluble lignin is then separated from the acidified second por-tion and at least the inorganic component of the secondportion is fed to the kraft recovery system.
The black liquor (b.l~) resulting from a kraft pulping process usually has a pH in the range of about 11 to 13 (typically about 12) and contains sodium carbonate and sodium sulfate, sodium sulfide and sodium organic salts. Before further treatment of the b.l.l the sulfide should be oxidized by blowing air through the liquor.
~ n a first embodiment, the concentrated b.l.
which is usually at a solids concentration of at least about 40%/ more typically about 50~ solids ls cooled to a temperature below about 50UC, preferably between about 5 and 40C. This can be done by a conventional heat exchange means. The cooled and concentrated b.l. is mixed with a steam containing sulfuric acid, where the pH
of the mixture is maintained at most about 5, preferably below about 4.5. The,sulfuric acid-containing bath use~
in this step can be the effluent from a chlorine dioxide generator associated with the bleaching facility of the kraft mill (which comprises sodium sulfate and sulfuric acid) or it can be conventional industrial grade sulfuric acid. This reduction of the pH results in the insolubilization of the lignin, as well as the conversion of the sugar acid salts in the b.l. to the corresponding ~L17;~
sugar acids as well as the substantial conversion of the sodium values to sodium sulfate. Similar conversions, such as sodium acetate to acetic acid, also occur during the acidification. The carbon dioxide and possi~ly some hydrogen sulfide which are formed during the acidifica-tion are removed during a degasification step, eg. by the reduction of pressure above the b.l. The gases evolved during the degasification can be passed through a scrub-ber, fed to a furnace or the like.
The acidified and degassed liquor is then heat-ed to temperature in excess of 60C, preferably to about 90C, possibly by the passage of steam or more preferably by the use of steam coils immersed ln the b.l~ The heat-ing serves to coagulate (or fuse) the lignin which tends to float to the surface because of the gas entrapped therein during its fusion and the high density of the concentrated b.l. The coagulated lignin is easily sepa-rated from the rest of the b.l. by skimming the surface, or decantation of the b.1. The lignin so ob~ained can be subjected to Eurther ahemical treatment if so desired, or used as a fuel eg. in a conventional boiler~ fluidized beds and ~he like.
Following the separation of the fused lignin, before feeding the residual b.l. to the kraft recovery furnace, sodium hydroxide should be added to the remain-ing b.1. in order to neutralise the excess acid therein if the residual alkali in the b~l. to which it is added is insufficient for this purpose. Alternatively, this residual liquor containing the sodium sulfate (anhydrous) and organics (including sugar acid salts) is then cooled to about 0C employing forced cooling means, whereby the anhydrous sodium sulfate hydrates, absorbing substantial quantities of water of crystallization from the surround-_ 5 _ ~ ~t7~ing solution, with one mole of the anhydrous sodlum sul-fate absorbing ten moles of water. This process of hydration of the sodium sulfate to glaubers salt reduces the ~ree water ~rom the residual b.1., leaving behind the sugar acids which are liquid and can consequently, be separated eg. by filtration, centrifugation etc. from the crystalline glaubers salt. The concentration of black liquor following the passage khrough the multiple effect evaporator, and the strength of the sulfuric acid should preferably be adjusted so as to ensure that the conc~n-tration of the anhydrous sodium sulfate in the residual liquor is such that the formation of glaubers salt will leave the organic acids and sugar acids substantially free of water.
The hydrated sodium sulfate can then be mixed with a conventional concentra~ed black liquor, eg. in a turbulent mixer before this concentrated black liquor is fed to the recovery furnace. This e~iminates the salt-cake makeup re~uired resulting from the loss of b.1. due to an overloaded recovery process. Since the inorc3anics added to the concentrated b.l. comprise essentially sodium sulfate, their reduction to a useable pulping chemical is easily accomplished in a kraft recovery furnace.
In a second embodiment of the present embodi ment, the temperature of an unconcentrated black liquor from a kraft pulping process is first adjusted to about 57-65~C, then it is acidified with an acid comprising sulfuric acid to a p~ of below about 5, but preferably below about 4O5~ so as to render insoluble the lignin contained therein and convert the sodium values therein to sodium sulfate. The acidified b.l. i8 maintained at a temperature in the range of about 57 - 65C in order to agglomerate the lignin particles to a size that facili-tates separation, eg. without blinding, clogging or gum-ming up the filter~ The agglomerated lignln is then separated ~rom the rest of the b.l. e.g. by filtration, centrifugation, etc. Following the removal of the lignin, the rest of the b.l. can be neutralized to pre-vent loss of organic acid volatiles in the following concentration step. It is then concentrated reacidified and cooled so as to form crystals of glaubers salt which can be sep~rated from the sugar acids, and/or the sugar acid salts before the salt cake is fed to the furnace as was described in the preceding embodiment. Alternative-ly, following the removal of the lignin the rest of the b.l. can be neutralized with sodium hydroxide or possibly by mixing with b.l. ~ontaining sufficient residual alkali before being fed to the recovery system~
Referring now to the single figure (Figure 1), which illustrates the ~irst embodiment of the present invention, we note tha~ the b.l. is first concentrated in a multiple effect evaporator (10) to at least about 40%
solids concentration (preferably about 50~ solids). The concentrated b.l. is then cooled eg. via heat exchange means (14) to a temperature at or below about 40C. The cooled black liquor is added to an acid bath (18) where its pH reduced to below about 3.5. The sulfuric acid containing bath in this case is preferably obtained from the liquid effluent of a chlorine dioxide generator (which includes sodium sulfate therein). The carbon dioxide, and possibly some hydrogen sulfide which are evolved, are separated from the acidified liquid in the degassing stage (22) possibly sent to the scrubbers and then the degassed liguid is heated (24) to a temperature in excess of about 60C, preferably by steam coils im~
mersed in the liquid. The gas evolved here can be passed through a scrubber, sent to a furnace, etc. The insolu-ble lignin which i~ fused by this heating is sep~rated in the following step (28) by decantation and the like. The decanted liquid is cooled to about 0C (by forced cooling means 30), the sodium sulfate permitted to hydrate sca-venge substantially all the water, and the hydrated sodi-um sulfate (glauber salt) separated eg. by filtration (36) from the residual organic and sugar acids. The sugar acids thus obtained can be used in any suitable mannerl possibly bein~ burnt in a conventional furnace.
The hydrated sodium sulfate can be mixed with concentrat-ed b.l. in a mixer (40) before being fed to the kraft recovery furnace (44). Alternatively, should the concen-trated b.l. which is being fed to the kraft recovery furnace contain residual alkali su~ficient to neutralize the decanted liquid, the acidic, decanted liquid can be directly neutralized in the mixer 40 ~as shown by the dotted line in figure 1), by the concentrated b.1., bypassing the intermediate cooling and separation stqps 32 and 36. Sodium sulfate will be obtained in a reduced ~orm ~rom the kraft furnace and is useable in further pulping of lignocellulosic material.
As will be evident from the foregoing this pro-cess effectively increases the inorganic recovery capaci-ty of a kraft recovery furnace without capital costs of the magnitude that would be conventionally incurred. The capacity for recovery of the organics contained in the b.l. is also augmented, by the recovery of liynin for its chemical or fuel value; and/or by the possible recovery of the sugar acid components. The lignin and/or sugars may be burned in the normally available bark burning equipment or the like.
Modifications can be made to the foregoing without departing ~rom the spirit of the invention as defined in the appended claims.
which are already running at capacity.
Brief Description of the Invention The presen~ invention relates to a kra~toverload recovery process for the recovery of black liquor (b.l.) resulting from a kraft pulping process in a kraft recovery system having a kraft recovery ~urnace comprising the steps of:
(a) feeding a first portion of the b.l. to said furnace, (b) acidifyin~ a second portion of said b.l.
with an acid comprising sulfuric acid so as to insolubilize substantially all the lignin contained in the second portion and form sodium sulfate, (c) separating the insoluble lignin from the rest of the acidi~ied second portion, the rest of the acidified second portion comprising organic and inorganic components, ~ d) feeding at least ~aid inorganic component, comprising the sodium sulfate to the kraft recovery system op~r~ting at capacity.
Brief Description of the ~rawings ., The single figure ~Figure 1) provides a sche-matic flow diagram of the preferred embodiment of the present invention.
Detailed Description of the Present Invention Accordingly, the present invention provides a process for treating black liquor which is a product of a kraft process for pulping lignocellulosic material. The process permits the recovery of lignin (and possibly sugar acids) and the recovery of inorganic values Erom the black liquor in excess of those recoverable by a fixed capacity kraft recovery system.
Broadly then, this process for augmenting the recovery capacity of a kraft recovery system already operating at capacity will comprise feeding a first por-tion of the b.l. to the kraft recovery system wbich is thus operating at capacity, acidifying a second portion of the b.l. with an acid containing sulfuric acid so as to insolubilize substantially all the lignin contained in the second portion and convert substantially all the sodium values therein to sodium sulfate. This insoluble lignin is then separated from the acidified second por-tion and at least the inorganic component of the secondportion is fed to the kraft recovery system.
The black liquor (b.l~) resulting from a kraft pulping process usually has a pH in the range of about 11 to 13 (typically about 12) and contains sodium carbonate and sodium sulfate, sodium sulfide and sodium organic salts. Before further treatment of the b.l.l the sulfide should be oxidized by blowing air through the liquor.
~ n a first embodiment, the concentrated b.l.
which is usually at a solids concentration of at least about 40%/ more typically about 50~ solids ls cooled to a temperature below about 50UC, preferably between about 5 and 40C. This can be done by a conventional heat exchange means. The cooled and concentrated b.l. is mixed with a steam containing sulfuric acid, where the pH
of the mixture is maintained at most about 5, preferably below about 4.5. The,sulfuric acid-containing bath use~
in this step can be the effluent from a chlorine dioxide generator associated with the bleaching facility of the kraft mill (which comprises sodium sulfate and sulfuric acid) or it can be conventional industrial grade sulfuric acid. This reduction of the pH results in the insolubilization of the lignin, as well as the conversion of the sugar acid salts in the b.l. to the corresponding ~L17;~
sugar acids as well as the substantial conversion of the sodium values to sodium sulfate. Similar conversions, such as sodium acetate to acetic acid, also occur during the acidification. The carbon dioxide and possi~ly some hydrogen sulfide which are formed during the acidifica-tion are removed during a degasification step, eg. by the reduction of pressure above the b.l. The gases evolved during the degasification can be passed through a scrub-ber, fed to a furnace or the like.
The acidified and degassed liquor is then heat-ed to temperature in excess of 60C, preferably to about 90C, possibly by the passage of steam or more preferably by the use of steam coils immersed ln the b.l~ The heat-ing serves to coagulate (or fuse) the lignin which tends to float to the surface because of the gas entrapped therein during its fusion and the high density of the concentrated b.l. The coagulated lignin is easily sepa-rated from the rest of the b.l. by skimming the surface, or decantation of the b.1. The lignin so ob~ained can be subjected to Eurther ahemical treatment if so desired, or used as a fuel eg. in a conventional boiler~ fluidized beds and ~he like.
Following the separation of the fused lignin, before feeding the residual b.l. to the kraft recovery furnace, sodium hydroxide should be added to the remain-ing b.1. in order to neutralise the excess acid therein if the residual alkali in the b~l. to which it is added is insufficient for this purpose. Alternatively, this residual liquor containing the sodium sulfate (anhydrous) and organics (including sugar acid salts) is then cooled to about 0C employing forced cooling means, whereby the anhydrous sodium sulfate hydrates, absorbing substantial quantities of water of crystallization from the surround-_ 5 _ ~ ~t7~ing solution, with one mole of the anhydrous sodlum sul-fate absorbing ten moles of water. This process of hydration of the sodium sulfate to glaubers salt reduces the ~ree water ~rom the residual b.1., leaving behind the sugar acids which are liquid and can consequently, be separated eg. by filtration, centrifugation etc. from the crystalline glaubers salt. The concentration of black liquor following the passage khrough the multiple effect evaporator, and the strength of the sulfuric acid should preferably be adjusted so as to ensure that the conc~n-tration of the anhydrous sodium sulfate in the residual liquor is such that the formation of glaubers salt will leave the organic acids and sugar acids substantially free of water.
The hydrated sodium sulfate can then be mixed with a conventional concentra~ed black liquor, eg. in a turbulent mixer before this concentrated black liquor is fed to the recovery furnace. This e~iminates the salt-cake makeup re~uired resulting from the loss of b.1. due to an overloaded recovery process. Since the inorc3anics added to the concentrated b.l. comprise essentially sodium sulfate, their reduction to a useable pulping chemical is easily accomplished in a kraft recovery furnace.
In a second embodiment of the present embodi ment, the temperature of an unconcentrated black liquor from a kraft pulping process is first adjusted to about 57-65~C, then it is acidified with an acid comprising sulfuric acid to a p~ of below about 5, but preferably below about 4O5~ so as to render insoluble the lignin contained therein and convert the sodium values therein to sodium sulfate. The acidified b.l. i8 maintained at a temperature in the range of about 57 - 65C in order to agglomerate the lignin particles to a size that facili-tates separation, eg. without blinding, clogging or gum-ming up the filter~ The agglomerated lignln is then separated ~rom the rest of the b.l. e.g. by filtration, centrifugation, etc. Following the removal of the lignin, the rest of the b.l. can be neutralized to pre-vent loss of organic acid volatiles in the following concentration step. It is then concentrated reacidified and cooled so as to form crystals of glaubers salt which can be sep~rated from the sugar acids, and/or the sugar acid salts before the salt cake is fed to the furnace as was described in the preceding embodiment. Alternative-ly, following the removal of the lignin the rest of the b.l. can be neutralized with sodium hydroxide or possibly by mixing with b.l. ~ontaining sufficient residual alkali before being fed to the recovery system~
Referring now to the single figure (Figure 1), which illustrates the ~irst embodiment of the present invention, we note tha~ the b.l. is first concentrated in a multiple effect evaporator (10) to at least about 40%
solids concentration (preferably about 50~ solids). The concentrated b.l. is then cooled eg. via heat exchange means (14) to a temperature at or below about 40C. The cooled black liquor is added to an acid bath (18) where its pH reduced to below about 3.5. The sulfuric acid containing bath in this case is preferably obtained from the liquid effluent of a chlorine dioxide generator (which includes sodium sulfate therein). The carbon dioxide, and possibly some hydrogen sulfide which are evolved, are separated from the acidified liquid in the degassing stage (22) possibly sent to the scrubbers and then the degassed liguid is heated (24) to a temperature in excess of about 60C, preferably by steam coils im~
mersed in the liquid. The gas evolved here can be passed through a scrubber, sent to a furnace, etc. The insolu-ble lignin which i~ fused by this heating is sep~rated in the following step (28) by decantation and the like. The decanted liquid is cooled to about 0C (by forced cooling means 30), the sodium sulfate permitted to hydrate sca-venge substantially all the water, and the hydrated sodi-um sulfate (glauber salt) separated eg. by filtration (36) from the residual organic and sugar acids. The sugar acids thus obtained can be used in any suitable mannerl possibly bein~ burnt in a conventional furnace.
The hydrated sodium sulfate can be mixed with concentrat-ed b.l. in a mixer (40) before being fed to the kraft recovery furnace (44). Alternatively, should the concen-trated b.l. which is being fed to the kraft recovery furnace contain residual alkali su~ficient to neutralize the decanted liquid, the acidic, decanted liquid can be directly neutralized in the mixer 40 ~as shown by the dotted line in figure 1), by the concentrated b.1., bypassing the intermediate cooling and separation stqps 32 and 36. Sodium sulfate will be obtained in a reduced ~orm ~rom the kraft furnace and is useable in further pulping of lignocellulosic material.
As will be evident from the foregoing this pro-cess effectively increases the inorganic recovery capaci-ty of a kraft recovery furnace without capital costs of the magnitude that would be conventionally incurred. The capacity for recovery of the organics contained in the b.l. is also augmented, by the recovery of liynin for its chemical or fuel value; and/or by the possible recovery of the sugar acid components. The lignin and/or sugars may be burned in the normally available bark burning equipment or the like.
Modifications can be made to the foregoing without departing ~rom the spirit of the invention as defined in the appended claims.
Claims (16)
1. A kraft overload recovery process for the re-covery of black liquor (b.1.) resulting from a kraft pulping process in a kraft recovery system having a kraft recovery furnace comprising the steps of:
(a) feeding a first portion of said b.1. to said furnace, (b) acidifying a second portion of said b.1.
with an acid comprising sulfuric acid so as to insolubilize substantially all the lignin contained in said second portion and form sodium sulfate, (c) separating said insoluble lignin from the rest of said acidified second portion, said rest of said acidified second portion comprising organic and inorganic components, (d) feeding at least said inorganic component comprising said sodium sulfate to said kraft recovery system operating at capacity.
(a) feeding a first portion of said b.1. to said furnace, (b) acidifying a second portion of said b.1.
with an acid comprising sulfuric acid so as to insolubilize substantially all the lignin contained in said second portion and form sodium sulfate, (c) separating said insoluble lignin from the rest of said acidified second portion, said rest of said acidified second portion comprising organic and inorganic components, (d) feeding at least said inorganic component comprising said sodium sulfate to said kraft recovery system operating at capacity.
2. A process as defined in Claim 1, wherein said second portion is concentrated to at least about 40%
solids and cooled to between about 5 and 50°C before said acidifying.
solids and cooled to between about 5 and 50°C before said acidifying.
3. A process as defined in Claim 2 wherein said acidifying reduces the pH of said portion to at most 4.5.
4. A process as defined in Claim 2, wherein the temperature of said acidified second portion is raised to at least about 60°C before said separating of said insol-uble lignin.
5. A process as defined in Claims 2 or 4 wherein said lignin in separated from said rest of said second portion by decantation.
6. Process as defined in Claims 2 or 4, wherein said rest of said second portion is cooled so as to hydrate and crystallize said sodium sulfate before said feeding of said inorganic component to said kraft recovery system.
7. Process as defined in Claim 1, wherein said rest of said acidified second portion is neutralized before feeding said inorganic component to said kraft recovery system.
8. Process as defined in Claim 7, wherein said neutralization of said acidified second portion is carried out by mixing said acidified, second portion with said first portion where said first portion contains sufficient alkali for said neutralization.
9. Process as defined in Claim 7, wherein addition of sodium hydroxide to said acidified second portion results in said neutralization.
10, Process as defined in Claim 1, where tempera-ture of said second portion is adjusted to the range of about 57 - 65°C before said separating of said lignin.
11. A process as defined in Claims 1 or 10, wherein said acidifying of said second portion is to a pH of at most 4.5.
12. Process as defined in Claim 10, wherein said separating of said insoluble lignin is accomplished by one of decantation, filtration and centrifugation.
13. Process as defined in Claim 10, wherein said rest of said acidified second portion is concentrated, and cooled so as to hydrate and crystallize said sodium sulfate before said feeding of said inorganic component to said Kraft recovering system.
14. Process as defined in Claims 1, 2 or 10, where-in said separated lignin is fed to a conventional boiler for recovery of its calorific value.
15. Process as defined in Claims 1, 2 or 10, wherein said separated lignin is burnt in a fluidized bed,
16. Process as defined in Claim 1, wherein said rest of said acidified second portion is neutralized before said inorganic component of said second portion is fed to said Kraft recovery furnace.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000382387A CA1172808A (en) | 1981-07-23 | 1981-07-23 | Kraft overload recovery process |
| SE8204364A SE8204364L (en) | 1981-07-23 | 1982-07-16 | KIT FOR TREATMENT OF BLACK FLUID FROM THE POWER MASS PROCESS |
| FI822591A FI75614C (en) | 1981-07-23 | 1982-07-22 | Overload power recycling process. |
| JP12883082A JPS5836292A (en) | 1981-07-23 | 1982-07-23 | Kraft overload recovery method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000382387A CA1172808A (en) | 1981-07-23 | 1981-07-23 | Kraft overload recovery process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172808A true CA1172808A (en) | 1984-08-21 |
Family
ID=4120514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382387A Expired CA1172808A (en) | 1981-07-23 | 1981-07-23 | Kraft overload recovery process |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5836292A (en) |
| CA (1) | CA1172808A (en) |
| FI (1) | FI75614C (en) |
| SE (1) | SE8204364L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1109659C (en) * | 1999-04-29 | 2003-05-28 | 中国科学院化工冶金研究所 | Method for recovering alkali from paper-making black liquor by using ammonium hydrogen carbonate as solvent |
| WO2012005677A1 (en) * | 2010-07-07 | 2012-01-12 | Stora Enso Oyj | Process for production of precipitated lignin from black liquor and precipitated lignin produced by the process |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE0402437D0 (en) * | 2004-10-07 | 2004-10-07 | Stfi Packforsk Ab | Method for separating lignin from a lignin containing liquid / slurry |
| CL2010001609A1 (en) * | 2010-12-29 | 2011-03-18 | Univ De Concepcion 50% | Process for obtaining tall oil util that comprises the reaction between a solution of sodium sesquisulfate and tall oil soap. |
| CN104178777B (en) * | 2014-07-18 | 2017-05-17 | 广西大学 | Method for recovering sodium hydroxide by combining lignin extraction from pulping alkaline waste liquid with electrolysis |
-
1981
- 1981-07-23 CA CA000382387A patent/CA1172808A/en not_active Expired
-
1982
- 1982-07-16 SE SE8204364A patent/SE8204364L/en not_active Application Discontinuation
- 1982-07-22 FI FI822591A patent/FI75614C/en not_active IP Right Cessation
- 1982-07-23 JP JP12883082A patent/JPS5836292A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1109659C (en) * | 1999-04-29 | 2003-05-28 | 中国科学院化工冶金研究所 | Method for recovering alkali from paper-making black liquor by using ammonium hydrogen carbonate as solvent |
| WO2012005677A1 (en) * | 2010-07-07 | 2012-01-12 | Stora Enso Oyj | Process for production of precipitated lignin from black liquor and precipitated lignin produced by the process |
| US9567360B2 (en) | 2010-07-07 | 2017-02-14 | Stora Enso Oyj | Process for production of precipitated lignin from black liquor and precipitated lignin produced by the process |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5836292A (en) | 1983-03-03 |
| FI75614C (en) | 1988-07-11 |
| FI822591A0 (en) | 1982-07-22 |
| FI822591L (en) | 1983-01-24 |
| SE8204364L (en) | 1983-01-24 |
| SE8204364D0 (en) | 1982-07-16 |
| FI75614B (en) | 1988-03-31 |
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