CN1175294A - Method to reduce silicon, phosphor and aluminium contents in green liquor - Google Patents
Method to reduce silicon, phosphor and aluminium contents in green liquor Download PDFInfo
- Publication number
- CN1175294A CN1175294A CN95197648A CN95197648A CN1175294A CN 1175294 A CN1175294 A CN 1175294A CN 95197648 A CN95197648 A CN 95197648A CN 95197648 A CN95197648 A CN 95197648A CN 1175294 A CN1175294 A CN 1175294A
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- China
- Prior art keywords
- sodium carbonate
- sodium
- solution
- silicon
- melt
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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
-
- 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
- D21C11/12—Combustion of pulp liquors
- D21C11/122—Treatment, e.g. dissolution, of the smelt
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/40—Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills
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- Paper (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Removal Of Specific Substances (AREA)
- Silicon Compounds (AREA)
Abstract
The present invention relates to a method of decreasing the silicon, phosphor and/or aluminium contents of the cooking chemicals in the recovery of chemicals in an alkali delignification process of cellulose-containing material. Melt containing sodium carbonate, obtained from combustion of black liquor is treated so that the sodium carbonate is recovered in solid form, whereas the silicon, the phosphor and/or the aluminium is separated as a solution containing dissolved sodium silicates, sodium phosphates, and/or sodium aluminates. The melt may either be dissolved and this solution may be evaporated so as to crystallize the sodium carbonate, or the silicon, phosphor, and/or aluminium compounds may be dissolved by leaching melt, whereby the sodium carbonate is obtained in solid form. The solid sodium carbonate is further dissolved to form a solution having a low silicon, phosphor, and/or aluminium content.
Description
The present invention relates to the method for silicon, phosphorus and/or aluminium content in a kind of cooking liquor that in the alkali delignification method of cellulose-containing material, reduces in the chemicals recovery.
In the country that lacks the trees resource, annual plant is used as the raw material of manufacturing chemistry paper pulp as bamboo, sugarcane, rice and wheat.The producer of this class paper pulp runs into and is different from the problem of making wood pulp fully.Generally speaking, these problems are owing to the small-scale of raw-material character and pulp mill.A basic problem is the recovery of boiling chemicals, and some character of waste liquid makes it more serious.Usually, recovery method is uneconomical, and little pulp mill does not reclaim chemicals usually.Because economic the variation and environmental factor finds that recently the development of chemicals recovery is more and more important.
The meristem of annual plant contains a large amount of silica (SiO
2).When with the branches and leaves slurrying of this class plant, the silicic acid that exists with particle form is dissolved as silicate ion in alkaline cooking liquor.Just because of lysed silica, from this cooking waste liquor, reclaim chemicals and be proved to be unusual difficulty.In alkaline cooking process, as sulfate and soda process, be that water in the black liquor reclaims chemicals by the evaporation waste liquid, burning is contained in organic substance in this liquid with the discharging chemicals in recovery furnace then.Chemicals discharges from recovery furnace with the form of melt, this melt formation green liquor soluble in water.Contain sodium carbonate in this green liquor, the oxidized calcium causticization of this sodium carbonate becomes NaOH required in the pulp product.The white liquid that obtains thus is recycled in the pulp product system, and the calcium carbonate of formation (lime mud) is regenerated in the limekiln.
The silica that is dissolved in the alkaline black liquor all causes trouble in all chemicals cyclic processes.At liquor evaporating plant, the silicate in the black liquor reaches its solubility limit, is deposited on the heat-transfer area of evaporimeter with the form of different compounds, hinders the operation of equipment thus.In recovery furnace, silicate also forms precipitation and increases chemical melt viscosity on heat-transfer area.In the causticization process, silicate form with the hydrogenation calcium silicates in lime mud precipitates.The lime mud infiltration of being rich in silicate is poor, stays moisture in lime mud.A large amount of alkali are brought in the limekiln with moisture, and this hinders the running in limekiln.Usually, this lime mud is unworthy burning, but has to be transported to buried regions.And the white liquid measure that obtains has thus reduced, and valuable boiling chemicals also comes to an end at buried regions with lime mud.
Do not discharge non-carbonate-free lime, and suggestion separates silica by using carbon dioxide that black liquor pH value is reduced in about 9.1～10.2 scopes from black liquor.In the black liquor of ionic species, promptly major part is HSO
3 4-And SiO
2 3-, lysed silica solubility reduces, and silica is with the form precipitation of santocedl.It is reported that in the method for the United Nations Industrial Development Organization (UNIDO) and the international development office of Sweden (SIDA) exploitation, even 90% silicate can be by rare black liquor (6 gram SiO
2/ successfully separate in l).In this case, carbon dioxide causes bubble and enters in the black liquor in a boiling reactor, and precipitated silica passes through isolated by filtration then.CPPRI and Lurgi have developed same equipment.Ubiquitous in these equipment is that in practice, they move unsatisfactory.Problem obviously is because the poor filterability of gelatinous precipitate, be contained in the black liquor lignin simultaneously with the precipitation of silica, chemicals follows organic substance to lose and the decline of black liquor calorific value.
Identical with the method for from black liquor, separating, use carbon dioxide that silica is separated from green liquor.Based on employed raw material, the silicate content in the green liquor is about 10～20 gram SiO
2/ l, sometimes even higher, the content that this is much higher than in corresponding rare black liquor is hopeful to obtain productive rate preferably like this.The separation of precipitation of silica from green liquor do not resemble from black liquor is a problem the separation, because lack organic substance in the green liquor.
Because the action pH of carbon dioxide reduces, but the free alkali that is contained in the green liquor disappears, and is replaced by carbonate and bicarbonate simultaneously, and they must be removed from green liquor in the causticization process.This has increased the needs of causticization greatly, and has increased the consumption of calcium oxide.
Other objectionable impurities that contain in the green liquor are phosphorus and aluminium.The same with silicon, their accumulation in the lime circulation, and form internal load therein.Therefore, for example, use new lime to replace to remove phosphorus by removing in the circulation a part of lime.Phosphorus tends to accumulate in the thin dirt in limekiln, and as possible, it is removed with this form usually just.In some place, thin dirt is sold as the phosphorated material that is used for the soil improvement purpose.
An object of the present invention is to provide a kind of method than silicon, phosphorus and aluminium content in simpler, the more effective basic reduction cooking liquor of art methods.Be focussed in particular on that above-mentioned impurity is changed into can segregative form.
In order to realize above-mentioned specific purposes, the present invention is characterised in that-black-liquor combustion melt that obtain and that contain sodium carbonate makes sodium carbonate reclaim with solid-state form through handling, and silicon, phosphorus and/or aluminium come out with the solution isolated in form of the sodium metasilicate, sodium phosphate and/or the sodium aluminate that contain dissolving; And-the dissolving solid sodium carbonate, to form the solution of low silicon, phosphorus and/or aluminium content.
Sodium metasilicate, sodium phosphate and sodium aluminate be almost ad infinitum dissolving in water, and the solubility of sodium carbonate in water is limited.According to the present invention, along with sodium carbonate becomes crystalline state, it may be separated from the mother liquor that is rich in sodium metasilicate, sodium phosphate and/or sodium aluminate with the form of pure sodium carbonate.After the separation, with crystal sodium carbonate dissolving, the solution that obtains like this through conventional processing, can output be used for the sodium hydroxide solution of slurrying and other demand in the causticization workshop.
In the chemical regeneration method of routine, contain the melt of sodium carbonate can be water-soluble or the rare white liquid from the lime mud washing in.As long as crystallization takes place, this sodium carbonate can be separated from this solution by evaporating liquid.Evaporation is a kind of multiple-effect method of routine.After the evaporation, crystal itself will be separated from the mother liquor that contains soluble sodium metasilicate, sodium phosphate and sodium aluminate with known method as filtering.
Sodium carbonate can be separated from easily molten silicate, phosphate and aluminate, also makes easily to dissolve compound and leach into small amount of liquid from the recovery furnace melt, and like this, the sodium carbonate of dissolving does not mainly remain solid-state so easily.Leaching can be passed through, and for example, uses the melt dissolving method by the Ebara exploitation, in conjunction with neutral sulphite semichemical pulp absorption method (United States Patent (USP) 4,212,702 and 4,141,785; Teder, A., Nordisck Cellulosa, 1984, No.2 pp.12-14) realizes.According to another kind of method, cooling caustic soda melt if necessary, is ground into it desirable particle size then and carries out leaching.
As previously mentioned, silicate uses the pulp mill of annual plant slurrying to make a special difficult problem to those.In this case, the delignification method generally is to use the soda process of NaOH as the boiling chemicals.But, the invention is not restricted to soda process, it also can correspondingly be applicable to the method for the cooking liquor that uses sulfur-bearing, as sulfate process.Yet, under the sort of situation, finally be in the mother liquor that contains sodium metasilicate than the more diffluent vulcanized sodium of sodium carbonate.And silicate, phosphate and/or aluminate can be for example, utilize lime or carbon dioxide precipitation and separate from mother liquor, thereby obtain a kind of solution of Containing Sulfur sodium, and return in the chemicals circulation of factory and go.
The superiority of method of the present invention remains highly significant, because its " refuse ", promptly sodium silicate solution has commercial value.In some aspects, its value even be higher than the instead of chemical medicine of the alkali that discharges in the divided silicon process (sodium carbonate does not all obtain with solid-state form in the melt; And part has been wasted with the form of solute).This situation may be favourable to those producers that make high paper pulp or secondary stock except that alkaline boiling.The peroxide bleaching of secondary stock promptly, uses a large amount of sodium metasilicate to prevent peroxide breakdown as stabilizing agent.FI patent 84190 also discloses the method that reclaims alkali from the spend scrub stream body.Therefore, above-mentioned alkali loss can remedy with the alkali that recovery process reclaims.Silicon can be effectively from containing silicate but remove the carbonate containing solution seldom, for example, use calcium oxide, because if opposite the obstruction uses calcium oxide to remove silicon from green liquor, causticizing reaction just can not take place.So superiority of the present invention not only is confined to the further utilization of sodium metasilicate.
Preferred use calcium oxide carries out " causticization " and can also remove other inorganic impurity from mother liquor.As a result, obtain a spot of silicon, phosphorus and the very high lime mud of aluminium content.Like this, reduced the amount of lime of discharging in the circulation, and might make the more valuable lime mud of soil improvement.
The great advantage of the method for divided silicon, phosphorus and aluminium is cheap operating cost according to the present invention.Compare with crystallization and evaporation, aspect operating cost and amount of investment, may be more useful by the leaching divided silicon.
Below with reference to accompanying drawing, by means of embodiment, further describe the present invention, wherein
Fig. 1 shows experimental result, the dioxide-containing silica of the cleaning green liquor that expression changes with the evaporation degree.
Fig. 2 illustrates a preferred embodiment of implementing the inventive method,
Fig. 3 illustrates second preferred embodiment of implementing the inventive method, and
Fig. 4 illustrates the 3rd preferred embodiment of implementing the inventive method.
Embodiment:
According to laboratory test, contain 48 gram SiO according to Fig. 1
2The dioxide-containing silica of the synthetic green liquor of/l reduces in the crystallization and evaporation process, and Fig. 1 shows SiO in the gained solution
2The relation of evaporation and concentration degree in content and the solution that has separated at crystals of sodium carbonate.
By the sodium and the silicone content of the crystal that separates in the assay laboratory, and calculate dioxide-containing silica in the green liquor of purification on this basis, in addition,, then calculate corresponding to the dioxide-containing silica under the initial situation if all sodium carbonate is separated.This result shows, green liquor is evaporated at 1/7 o'clock that is about initial volume, obtains a kind of end product, and it is the green liquor that dioxide-containing silica is about 5g/l.This value still can further improve by more effective crystal washing.
In the laboratory, silica is leached in the water of a small amount of room temperature from the sodium metasilicate that grinds and sodium carbonate melt.Find the leaching temperature and the optimization in processing time, may reach with use the same low silicone content of crystallization and evaporation method.
Fig. 2 illustrates a kind of method of utilizing crystallization and evaporation that sodium carbonate is separated from green liquor.By nozzle 2 black liquor is added in the waste liquid stove 1, there with air 3 burnings.Like this, the contained inorganic substances of black liquor remain melt at furnace bottom, depend on boiling method, and these inorganic substances mainly are sodium carbonate, or sodium carbonate and vulcanized sodium.Thus, melt self adds a dissolver in known manner, and there, it forms green liquor by pipeline 5 in the water-soluble or weak lye.Because contain insoluble impurities in the green liquor, it will be clarified or filter to remove the green liquor slag usually.Filter 6 is preferably the filter that is disclosed among International Patent Application PCT/FI94/-00485.Be delivered to vaporising device 8 through the green liquor that filters by pipeline 7.
Evaporation is most preferably finished several functions and is used downward film evaporator, and portion's green liquor is that pipe or plate outer surface flow along vaporising device within it.When the evaporation green liquor, concentrate and make crystallize sodium carbonate.By regulating the water yield of removing in the evaporation, the crystallize sodium carbonate of required part is come out.
Crystalliferous green liquor is discharged into the crystal separation operation by pipeline 9 from the evaporimeter fluid circulation system, in this case, finishes by filter 10.The filtrate that contains silicate, phosphate and/or aluminate is collected in order to further utilizing through piping 11.Crystals of sodium carbonate 12 is dissolved in the blending tank 14 becomes liquid, in this case concentrate 15 is collected from the condenser 16 of evaporimeter.Like this, obtain green liquor 17, about silicon, phosphorus and/or aluminium, it is recently purer from the initial green liquor that dissolves device 4.This purer green liquor carries out causticization with the method that became known in the delignification originally.
Alkali may be with filtrate 11 wastes.This alkali replenishes with adding alkali 13 adding blending tanks 14.
The method of second kind of separate solid sodium carbonate of figure .3 explanation.This method is based on the more diffluent compound of leaching, that is, sodium metasilicate, sodium phosphate and sodium aluminate make the most insoluble sodium carbonate keep solid-state to more a spot of water or to rare white liquid.
Melt is transported to the hopper 21 from recovery furnace 1 bottom, and the slurry with the sodium metasilicate that contains solid sodium carbonate, sodium phosphate and sodium aluminate solution contacts there.Like this, melt dissolving and be cured as granule.Minimum particle is through screen cloth 23 and enter dissolving tank 24, and wherein sodium metasilicate, sodium phosphate and sodium aluminate are by dissolving in the particle.The thickest particle is delivered to second dissolving tank 25, and their dissolvings and adding moisture 29 dissolve there.This solution is gone into first dissolving tank 24 from jar 25 overflows, and the lime mud that contains solid sodium carbonate therefrom is delivered into filter 28 by pipeline 27 separates solid crystals from mother liquor.
Crystals of sodium carbonate is dissolved in the water in jars 30, thus sodium carbonate liquor 31 is carried out causticization with known method self.The filtrate of processing from the pipeline 32 of filter 28 is to remove silicate, phosphate and aluminate.Adding calcium oxide or milk of lime through piping 33 makes be settled out silicate, phosphate and aluminate in clarifier 34.The silicon that purified, phosphorus and/or aluminium free base solution 35 are returned chemicals circulation by pipeline 31, and siliceous, the phosphorus in the conduit 36 and/or the slag of aluminium are used with products for further.
In Fig. 4, finish with a kind of other method from the leaching of the melt of recovery furnace.Melt dissolves and cools off in cooler 41 with air nozzle 40.Consequent hot-air is as the combustion air 42 of recovery furnace 1.
With the salt fragmentation of crushing machine 43 with curing.In dissolver 44,, make the dissolving of sodium metasilicate, sodium phosphate and sodium aluminate, and that sodium carbonate keeps mainly is solid-state with a certain amount of water leaching.With filter 45 this sodium carbonate is separated.Remove contain silicate, phosphate and aluminate in the pipeline 46 filtrate with further utilization, and sodium carbonate is dissolved in dissolver in the water from pipeline 48.Alkali with filtrate loss remedies with the alkali 49 that adds.As mentioned above, this sodium carbonate liquor is sent into the causticization operation through pipeline 50.
Details of the present invention may be different from and depart from the foregoing description details in the invention scope that claims limit.
Claims (11)
1. the method for silicon, phosphorus and/or the aluminium content in the cooking liquor that the reduction chemicals reclaims in the alkali delignification method of cellulose-containing material is characterized in that
-handle the melt that contains sodium carbonate obtain by black-liquor combustion sodium carbonate is reclaimed with solid-state form, and silicon, phosphorus and/or aluminium come out with the solution isolated in form of the sodium metasilicate, sodium phosphate and/or the sodium aluminate that contain dissolving; And
This solid sodium carbonate of-dissolving is to form the solution of low silicon, phosphorus and/or aluminium content.
2. the method for claim 1 is characterized in that dissolving the melt that is obtained by black-liquor combustion, and the solution that evaporation obtains thus makes crystallize sodium carbonate.
3. the method for claim 1 is characterized in that melt that water or aqueous solution leaching are obtained by black-liquor combustion obtains containing the solution of sodium metasilicate, sodium phosphate and/or sodium aluminate of dissolving and the solid particle that contains sodium carbonate.
4. the method for claim 1 is characterized in that being cooled off with air by the melt that black-liquor combustion obtains, and carries out leaching then.
5. method as claimed in claim 4, heated air is as the combustion air in the black-liquor combustion when it is characterized in that cooling off melt.
6. the method for claim 1 is characterized in that the solution that contains sodium metasilicate that separates with sodium carbonate is used for the bleaching or the practical application in addition of paper pulp.
7. the method for claim 1 adds the material that makes precipitation of silica in the solution that contains sodium metasilicate that it is characterized in that separating with sodium carbonate, preferably comes divided silicon with calcium oxide.
8. the method for claim 1 is characterized in that silicon being precipitated out with the form of silicon dioxide colloid and it being separated with the solution that contains sodium metasilicate that the gas treatment that contains carbon dioxide is separated with sodium carbonate.
9. method as claimed in claim 2, the water that separates in it is characterized in that evaporating is used for dissolving crystals of sodium carbonate.
10. the method for claim 1 is characterized in that this alkali delignification finishes by a kind of caustic soda method.
11. the method for claim 1 is characterized in that this alkali delignification finishes by a kind of sulfate process.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI950692A FI98225C (en) | 1995-02-16 | 1995-02-16 | Procedure for Removing Harmful Impurities in Alkaline Delignification of Cellulosic Material |
| FI950692 | 1995-02-16 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1175294A true CN1175294A (en) | 1998-03-04 |
| CN1088130C CN1088130C (en) | 2002-07-24 |
Family
ID=8542868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN95197648A Expired - Fee Related CN1088130C (en) | 1995-02-16 | 1995-10-09 | Method to reduce silicon, phosphor and aluminium contents in green liquor |
Country Status (5)
| Country | Link |
|---|---|
| CN (1) | CN1088130C (en) |
| AU (1) | AU3655295A (en) |
| FI (1) | FI98225C (en) |
| WO (1) | WO1996025554A1 (en) |
| ZA (1) | ZA958530B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102041703A (en) * | 2010-12-02 | 2011-05-04 | 陕西科技大学 | Process for removing silicon in green liquor of papermaking alkali recovery section by seeding |
| CN102619123A (en) * | 2012-03-16 | 2012-08-01 | 陕西科技大学 | Method for removing silicon from green liquor through synergism of calcium oxide, carbon dioxide and aluminum-containing compound |
| CN105839173A (en) * | 2016-03-21 | 2016-08-10 | 中国制浆造纸研究院 | Preparation method of white mud calcium carbonate whisker |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103469664B (en) * | 2013-08-26 | 2015-09-16 | 陕西科技大学 | A kind of alkali collection workshop section green liquor flocculation silicon removing method |
| CN115652676B (en) * | 2022-11-17 | 2023-09-26 | 陕西科技大学 | Green liquid silicon removal process for pre-stage silicon removal process |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3945880A (en) * | 1974-08-05 | 1976-03-23 | Erco Envirotech Ltd. | Sodium chloride removal in pulp mill systems |
| SE7809167L (en) * | 1978-08-30 | 1980-03-01 | Rosenblads Patenter Ab | BALLAST REDUCTION |
-
1995
- 1995-02-16 FI FI950692A patent/FI98225C/en not_active IP Right Cessation
- 1995-10-09 CN CN95197648A patent/CN1088130C/en not_active Expired - Fee Related
- 1995-10-09 WO PCT/FI1995/000556 patent/WO1996025554A1/en active Application Filing
- 1995-10-09 AU AU36552/95A patent/AU3655295A/en not_active Abandoned
- 1995-10-10 ZA ZA958530A patent/ZA958530B/en unknown
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102041703A (en) * | 2010-12-02 | 2011-05-04 | 陕西科技大学 | Process for removing silicon in green liquor of papermaking alkali recovery section by seeding |
| CN102619123A (en) * | 2012-03-16 | 2012-08-01 | 陕西科技大学 | Method for removing silicon from green liquor through synergism of calcium oxide, carbon dioxide and aluminum-containing compound |
| CN105839173A (en) * | 2016-03-21 | 2016-08-10 | 中国制浆造纸研究院 | Preparation method of white mud calcium carbonate whisker |
Also Published As
| Publication number | Publication date |
|---|---|
| FI98225C (en) | 1997-05-12 |
| FI950692A0 (en) | 1995-02-16 |
| FI98225B (en) | 1997-01-31 |
| ZA958530B (en) | 1996-05-10 |
| FI950692A (en) | 1996-08-17 |
| AU3655295A (en) | 1996-09-04 |
| WO1996025554A1 (en) | 1996-08-22 |
| CN1088130C (en) | 2002-07-24 |
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Granted publication date: 20020724 Termination date: 20101009 |