SE501877C2 - Procedure for precipitating magnesium with aluminum during green clearing - Google Patents
Procedure for precipitating magnesium with aluminum during green clearingInfo
- Publication number
- SE501877C2 SE501877C2 SE9401663A SE9401663A SE501877C2 SE 501877 C2 SE501877 C2 SE 501877C2 SE 9401663 A SE9401663 A SE 9401663A SE 9401663 A SE9401663 A SE 9401663A SE 501877 C2 SE501877 C2 SE 501877C2
- Authority
- SE
- Sweden
- Prior art keywords
- aluminum
- green liquor
- magnesium
- mill
- liquor
- Prior art date
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
- D21C11/0085—Introduction of auxiliary substances into the regenerating system in order to improve the performance of certain steps of the latter, the presence of these substances being confined to the regeneration 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
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor
- D21C11/0078—Treatment of green or white liquors with other means or other compounds than gases, e.g. in order to separate solid compounds such as sodium chloride and carbonate from these liquors; Further treatment of these compounds
-
- 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
Landscapes
- Paper (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Description
501 877 2 Det har även visat sig att finfördelade fällningar av vissa metallhydroxi- der, t.ex. magnesiumhydroxid, i grönluten får den att sedimentera långsamt. En hög halt av magnesium i grönlutsslammet kan resultera i dålig sedimentering av grönlutsslammet och följaktligen stor risk för att grönlutsslam förs vidare i processen till kausticeringssteget. Vid en mycket hög magnesiumhalt i kalk- cykeln kan kalkslammets filtrerbarhet allvarligt försämras (Per Ulmgren, "SCAN-FORSK REPORT", 535, juni 1989, sid. 21-23). 501 877 2 It has also been found that finely divided precipitates of certain metal hydroxides, e.g. magnesium hydroxide, in the green liquor it causes it to settle slowly. A high content of magnesium in the green liquor sludge can result in poor sedimentation of the green liquor sludge and consequently a high risk that green liquor sludge is passed on in the process to the causticisation step. At a very high magnesium content in the lime cycle, the filterability of the lime sludge can be seriously impaired (Per Ulmgren, "SCAN-FORSK REPORT", 535, June 1989, pp. 21-23).
Föreliggande uppfinning baserar sig på den insikten att utfällningen i grönlut av magneisum som ren magnesiumhydroxid, vilken är svårfiltrerbar, måste minskas och detta uppnås enligt föreliggande uppfinning genom att tillsätta aluminium till processen och fälla ut magnesium och aluminium i grönluten tillsammans som hydrotalcit, som är en relativt lättfiltrerad magne- sium-alurnixiiurrifällning. Magnesium och aluminium utfälles tillsammans som hydrotalcit i ett förhållande av ungefär 4 g Mg per 1 g Al.The present invention is based on the realization that the precipitation in green liquor of magnesium as pure magnesium hydroxide, which is difficult to digest, must be reduced and this is achieved according to the present invention by adding aluminum to the process and precipitating magnesium and aluminum in the green liquor together as hydrotalcite. relatively easily maglterated magnesium-alurnixiiurri precipitation. Magnesium and aluminum precipitate together as hydrotalcite in a ratio of about 4 g Mg per 1 g Al.
Aluminium betraktas ju som en besvärande föroreining i alla återvinnings- anläggningar inom sulfatmassaindustrin, då aluminium skapar beläggningar i återvinningsprocessens indunstningsavsnitt. I fabriker som har infört syrgas- delignifiering har emellertid aluminiumhalten, tack vare det till syrgasdelignifie- ringen tillförda magnesiumet, reducerats så mycket att aluminium upphört att skapa beläggningar. Det måste anses vara synnerligen överraskande att dessa fabriker istället drabbats av aluminiumbrist.Aluminum is considered a troublesome pollutant in all recycling plants in the sulphate pulp industry, as aluminum creates coatings in the evaporation section of the recycling process. However, in factories that have introduced oxygen delignification, the aluminum content, thanks to the magnesium added to the oxygen delignment, has been reduced so much that aluminum has ceased to form coatings. It must be considered particularly surprising that these factories have instead suffered from aluminum shortages.
I ovan nämnda "SCAN-FORSK"-rapport, sid. 28, står det att intaget av aluminium till sulfatmassaprocessen bör minimeras och ett antal metoder för att minska aluminiumintaget föreslås.In the above-mentioned "SCAN-RESEARCH" report, p. 28, it states that the intake of aluminum for the sulphate pulp process should be minimized and a number of methods to reduce the aluminum intake are proposed.
US 4.218.284 avser ett förfarande för inhibition av bildningen av inkruster vid massatillverkning genom tillsats av föreningar av flervärda metaller, vilka har förmåga att bilda komplex med inkrustbildande anjoner, varigenom de inkrustbildande anjonema hålles i form av ett lutlösligt komplex. Enligt patent- kravet 2 kan därvid den flervärda metallen vara aluminium. Emellertid berör denna patentskrift icke alls problemet med grönlutens filtrerbarhet utan förfaran- det utnyttjar aluminiumets förmåga att bilda lutlösliga komplex av inkrustbil- dande anjoner och ej dess förmåga att bilda en lättfiltrerbar fällning med magnesium i form av hydrotalcit.US 4,218,284 relates to a process for inhibiting the formation of incrustations in pulping by the addition of compounds of polyvalent metals which are capable of forming complexes with crust-forming anions, whereby the crust-forming anions are kept in the form of a lye-soluble complex. According to claim 2, the polyvalent metal can then be aluminum. However, this patent does not at all address the problem of the filtrability of green liquor, but the process utilizes the ability of aluminum to form alkali-soluble complexes of crust-forming anions and not its ability to form an easily filterable precipitate with magnesium in the form of hydrotalcite.
US 4.049.489 har till syfte att minska mängden svavel och klor i kokluten, vilka mängder kan uppnå icke önskvärda nivåer på grund av miljörestriktioner.US 4,049,489 aims to reduce the amount of sulfur and chlorine in the cooking liquor, which amounts can reach undesirable levels due to environmental restrictions.
Enligt denna patentskrift bränner man därför vissa metaller, exempelvis alumi- s o 1 87 7 - 3 nium, tillsammans med avluten, och dessa metaller bildar därvid föreningar med svavlet och kloren, vilka lätt kan separeras från de kemikalier som deltar i den normala processcykeln. Icke heller denna patentskrift behandlar problemet med grönlutens filtrerbarhet.According to this patent, therefore, certain metals, for example aluminum, are burned together with the liquor, and these metals thereby form compounds with the sulfur and chlorine, which can be easily separated from the chemicals participating in the normal process cycle. Nor does this patent address the problem of green liquor digestibility.
JP 60.045.692 avser rening av grönlut genom tillsats av aluminium eller magnesium. Syftet med uppfinningen enligt denna patentpublikation är att utfälla kiseldioxid och därefter separera denna från grönluten genom tillsats av ett magnesium- eller aluminiumsalt. Nämnda patentpublikation berör emellertid icke samutfällning av magnesium och alurninium.JP 60,045,692 relates to the purification of green liquor by the addition of aluminum or magnesium. The object of the invention according to this patent publication is to precipitate silica and then separate it from the green liquor by adding a magnesium or aluminum salt. However, said patent publication does not concern co-precipitation of magnesium and alurninium.
Den SCAN-FORSK-rapport vartill hänvisas ovan föreslår satsning av magnesium som medel för att minska aluminium i grönlut. Syftet med denna tillsats är att minska aluminiuminkruster vid indunstningen. Det föreliggande uppfinning föreslår är emellertid raka motsatsen, dvs. att satsa aluminium för att minska utfällning av magnesium som ren magnesiumhydroxid.The SCAN-FORSK report referred to above proposes investing magnesium as a means of reducing aluminum in green liquor. The purpose of this additive is to reduce aluminum increments during evaporation. However, the present invention proposes is the exact opposite, i.e. to invest in aluminum to reduce precipitation of magnesium as pure magnesium hydroxide.
Föreliggande uppfinning avser närmare bestämt ett förfarande för att förbättra grönlutens filtrerbarhet vid sulfatmassaprocessen, vilket förfarande utmärkas av att till processen sättes aluminium i form av elementärt aluminium eller en aluminiumhaltig kemisk förening i en sådan mängd att huvuddelen av grönlutens magneisuminnehåll utfälles tillsammans med aluminium i form av hydrotalcit och att optimal halt av aluminium uppnås i den klarnade grönluten.More particularly, the present invention relates to a process for improving the filterability of green liquor in the sulphate pulp process, which process is characterized in that aluminum is added to the process in the form of elemental aluminum or an aluminum-containing chemical compound in such an amount that the bulk of the green liquor hydrotalcite and that optimal content of aluminum is achieved in the clarified green liquor.
Företrädesvis satsas aluminiumet före sodapannan, vilket gör det möjligt att fritt välja i vilken form aluminiumet skall satsas. Aluminiumet kan även t.ex. sättas till grönluten före klarningssteget eller direkt in i sodapannan.Preferably, the aluminum is charged before the recovery boiler, which makes it possible to freely choose in which form the aluminum is to be charged. The aluminum can also e.g. add to the green liquor before the clarification step or directly into the recovery boiler.
Mängden satsat aluminium är sådan att man uppnår en halt av 5-50 mg/1, företrädesvis 5-15 mg/l i den klamade grönluten.The amount of aluminum charged is such that a content of 5-50 mg / l, preferably 5-15 mg / l in the clammy green liquor is achieved.
Vi har närmare studerat magnesium- och aluminiumhalternas variation med filterkapaciteten vid filtrering av* grönlutsslam i tre olika anläggningar (bruk I, bruk II, och bruk III) och resultaten redovisas i tabellen nedan. 501 877 4 Tabell: Kapacitet i m°"/tim. och halter i mg/l Bruk Mg i Mg i Al i Al i Mg/Al i Filter- Slam- ofiltre- filtre- ofiltre- filtre- ofiltre- kapaci- halt rad rad rad rad rad tet grönlut grönlut grönlut grönlut grönlut Bruk 90,4 ' o 10,4 2 8,7 1 sso III Bruk I 108 0 23,1 9,6 4,7 2,3 1520 Bruk 125 0 16,2 2,3 7,8 1,9 ca HI 21) ÖÛÛÛ Bruk II 47 0 37 26 1,3 1,9 900 1) Korsnäs-metoden Utgående från ovan angivna KORSNÄS-metod (SE 456.254), som innebär att man förbättrar filtreringsegenskaperna genom inblandning av en mindre mängd kalk i grönluten, kan man anta att filterkapaciteten skulle öka med slamhalten. I Bruk III gjordes- försök med förkalkning och på så sätt kunde filterkapaciteten ökas. Förkalkningsförsöken redovisas som "Bruk III, 2" i tabellen ovan.We have studied in more detail the variation of magnesium and aluminum contents with the filter capacity when filtering * green liquor sludge in three different plants (mill I, mill II, and mill III) and the results are reported in the table below. 501 877 4 Table: Capacity in ° / / and concentrations in mg / l Use Mg in Mg in Al in Al in Mg / Al in Filter- Slam- o oltre- filtre- o filtre- filtre- o filtre- capacity row row row row row tet green liquor green liquor green liquor green liquor green liquor Mill 90,4 'o 10,4 2 8,7 1 sso III Mill I 108 0 23,1 9,6 4,7 2,3 1520 Mill 125 0 16,2 2, 3 7.8 1.9 approx. HI 21) ÖÛÛÛ Mill II 47 0 37 26 1.3 1.9 900 1) The Korsnäs method Based on the above-mentioned KORSNÄS method (SE 456.254), which means that the filtration properties are improved by mixing of a small amount of lime in the green liquor, it can be assumed that the kap lter capacity would increase with the sludge content.
I tabellen syns relativt tydligt att KORSNÄS-metoden har en positiv effekt på filterkapaciteten. I bruk III nåddes dock ej lika hög kapacitet som i bruk II trots att grönluten förkalkats. Förklaringen menar vi står att finna i det faktum att bruk III har en mycket låg aluminiumhalt i den klamade grönluten vilket betyder att magnesium i grönlutslammet delvis föreligger i formen magnesium- hydroxid.The table shows relatively clearly that the KORSNÄS method has a positive effect on the fi lter capacity. In mill III, however, the capacity was not reached as high as in mill II, despite the green liquor being calcified. We believe that the explanation can be found in the fact that mill III has a very low aluminum content in the clammy green liquor, which means that magnesium in the green liquor sludge is partly present in the form magnesium hydroxide.
Som ses i tabellen förbrukas nästan allt aluminium i Bruk III för fällning av magnesium. Förklaringen härtill skulle vara att det finns svårfiltrerad magne- siumhydroxid i detta bruks grönlutsslam. Som framgår av tabellen är grön- lutarna i Bruk I och Bruk II betydligt lättare att filtrera än luten i Bruk III och, eftersom det fimis aluminium kvar i den filtrerade grönluten i Bruk I och Bruk II, är den troliga förklaringen att magnesiumet i grönlutsslammet här föreligger i hydrotalcitform. v Û 1 8 7 7 ^ 5 För Bruk III-anläggningen skulle således krävas cirka 50 g aluminium per ton massa i deras grönlut för att binda magnesium i grönluten. Bruk III produ- cerar cirka 40 ton/timme, vilket betyder att minst 2 kg aluminium per timme måste satsas.As can be seen in the table, almost all aluminum in Mill III is consumed for precipitating magnesium. The explanation for this would be that there is difficult filterated magnesium hydroxide in this mill's green liquor sludge. As can be seen from the table, the green liquors in Mill I and Mill II are much easier to filter than the liquor in Mill III and, since there is fi mis aluminum left in the filtered green liquor in Mill I and Mill II, the probable explanation is that the magnesium in the green liquor sludge here present in hydrotalcite form. v Û 1 8 7 7 ^ 5 For the Bruk III plant, approximately 50 g of aluminum per tonne of pulp in their green liquor would thus be required to bind magnesium in the green liquor. Mill III produces approximately 40 tonnes / hour, which means that at least 2 kg of aluminum per hour must be invested.
Claims (3)
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9401663A SE9401663L (en) | 1994-05-13 | 1994-05-13 | Procedure for precipitating magnesium with aluminum during green clearing |
CA002188941A CA2188941A1 (en) | 1994-05-13 | 1995-04-26 | Method for improving capacity when filtering green liquor |
AU25411/95A AU2541195A (en) | 1994-05-13 | 1995-04-26 | Method for improving capacity when filtering green liquor |
PCT/SE1995/000461 WO1995031600A1 (en) | 1994-05-13 | 1995-04-26 | Method for improving capacity when filtering green liquor |
JP7529551A JPH10500180A (en) | 1994-05-13 | 1995-04-26 | How to improve the ability when filtering green liquor |
FI964547A FI964547A0 (en) | 1994-05-13 | 1996-11-13 | Method for increasing the capacity in green liquor filtration |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9401663A SE9401663L (en) | 1994-05-13 | 1994-05-13 | Procedure for precipitating magnesium with aluminum during green clearing |
Publications (3)
Publication Number | Publication Date |
---|---|
SE9401663D0 SE9401663D0 (en) | 1994-05-13 |
SE501877C2 true SE501877C2 (en) | 1995-06-12 |
SE9401663L SE9401663L (en) | 1995-06-12 |
Family
ID=20394001
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
SE9401663A SE9401663L (en) | 1994-05-13 | 1994-05-13 | Procedure for precipitating magnesium with aluminum during green clearing |
Country Status (6)
Country | Link |
---|---|
JP (1) | JPH10500180A (en) |
AU (1) | AU2541195A (en) |
CA (1) | CA2188941A1 (en) |
FI (1) | FI964547A0 (en) |
SE (1) | SE9401663L (en) |
WO (1) | WO1995031600A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI107743B (en) * | 1999-01-12 | 2001-09-28 | Andritz Ahlstrom Oy | Procedure for reducing the silica content of the green liquor |
JP2023537805A (en) * | 2020-05-22 | 2023-09-06 | スザノ・エス.エー. | How to treat the kraft process recovery cycle to reduce metal levels in the kraft process |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE456254B (en) * | 1987-02-12 | 1988-09-19 | Korsnes Ab | SET TO CLEAN GROUNDLUT IN SULPHATE MASFACTURER'S CHEMICALS RECOVERY |
SE500660C2 (en) * | 1992-12-03 | 1994-08-01 | Mo Och Domsjoe Ab | Process for the production of green liquor in chemical recycling in sulphate and sulphite pulp mills |
-
1994
- 1994-05-13 SE SE9401663A patent/SE9401663L/en not_active IP Right Cessation
-
1995
- 1995-04-26 CA CA002188941A patent/CA2188941A1/en not_active Abandoned
- 1995-04-26 AU AU25411/95A patent/AU2541195A/en not_active Abandoned
- 1995-04-26 WO PCT/SE1995/000461 patent/WO1995031600A1/en active Application Filing
- 1995-04-26 JP JP7529551A patent/JPH10500180A/en active Pending
-
1996
- 1996-11-13 FI FI964547A patent/FI964547A0/en unknown
Also Published As
Publication number | Publication date |
---|---|
CA2188941A1 (en) | 1995-11-23 |
AU2541195A (en) | 1995-12-05 |
JPH10500180A (en) | 1998-01-06 |
SE9401663L (en) | 1995-06-12 |
FI964547A (en) | 1996-11-13 |
SE9401663D0 (en) | 1994-05-13 |
WO1995031600A1 (en) | 1995-11-23 |
FI964547A0 (en) | 1996-11-13 |
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Legal Events
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NUG | Patent has lapsed |