SE508227C2 - Extraction agents included essential oils and process for using them - Google Patents

Abstract

Liquid extraction agents for ions comprising one or more components with ion exchange properties selected from the group natural or synthetic ethereal oils, preferably turpentine oils, and distillation and/or hydrogenation and/or rearrangement products of these, optionally in combination with one or more organic solvents and optionally also comprising organophilic chelating agents and/or hydrophilic chelating agents and/or organophilic ion active compounds. The extraction agent preferably is essentially water insoluble or has a restricted solubility in water and is useful for extraction of ions from both solid and liquid phase, especially metal ions from lignocellulose, preferably with simultaneous metal ion extraction and/or anion extraction and delignification and bleaching of lignocellulose. A special application is to remove from lignocellulose incrust forming and bleaching retardant metal ions with simultaneous delignification in closed system under EFM (Effluent Free Mill) conditions.

Description

508 227 2 chlorine dioxide has been used for bleaching-delignification of chemical pulps.

However, this entails emissions to the recipients of organochlorine compounds, defined and quantified as so-called adsorbable organic halogens (AOX). Of the mentioned bleaching chemicals, chlorine dioxide gives at least AOX under the same conditions and the permitted levels of AOX in emissions from bleachers have been gradually reduced so much and are now at such low levels that the pulp mills in at least Scandinavia and the rest of Europe have switched to chlorine dioxide alone. ECF- (Elementally Chlorine Free) -bleaching- delignification to be able to meet the goals. However, the use of chlorine dioxide has also been questioned by the pressure from various consumer organizations, which require paper products bleached completely without chlorine-based chemicals at all, and in addition, restrictions on emissions of organochlorine compounds have become so strict in some countries that the requirements for low AOX levels are difficult to meet. even if only chlorine dioxide was used.

ECF and TCF bleaching The growing environmental concerns about emissions containing these organic chlorine compounds, AOX, have thus during this decade accelerated the rapid development of chlorine-free process steps including oxygen (0), ozone (Z) and hydrogen peroxide (P) as a complement. to chlorine dioxide step (D) at so-called ECF (elementally chlorine free) bleaching delignification of sulphate pulps in e.g. the sequence [ODQPD], where Q is a step for treatment with complexing agents, but also in that the chlorine dioxide in TCF bleaching delignification, to lower AOX to some extent has also come to replace even closer to zero in e.g. the sequence [OQPPP].

The Q-step has been introduced because the chlorine-free alternatives require very good metal ion control. Through the introduction of new cooking methods, e.g. s.k. "Modified Continous Cooking" (MCC), "Iso Thermal Cooking" (ITC) and "Superbatch Cooking", and application of sequential bleaching with oxygen, ozone and hydrogen peroxide in e.g. sequence [OZQ (EOP) P] in TCF bleaching / delignification, it has been possible to achieve brightness levels comparable to oxygen and chlorine dioxide [ODD] in ECF bleaching - delignification, i.e. about 90 508 227 3% ISO, without significantly impairing the CED (cupriethylenediamine) viscosity of the pulp, usually according to TAPPI or SCAN, with which the degree of degradation of the cellulose in the various process steps can be measured.

Transition metals A key factor in achieving this in TCF production is that the levels of ions of transition metals in the pulp in the above-mentioned chlorine-free bleaching steps are low, preferably close to zero level in at least the peroxide step (P), since in particular manganese causes serious disturbances in bleaching with peroxide by to catalyze certain side reactions, in which free radicals are involved, which attack the carbohydrate chains. This means that one must remove manganese before the P-step, usually by adding complexing agents in a so-called Q-step before one or more P-steps in the bleaching plant. A frequently applied method is described in SE-A-8902058, the so-called

The Lignox method (EKA Nobel). Through our introduction of a new method, described in U.S.P 5.57l, 378, the so-called The Hampox-Q process (Hampshire Chemical AB) has further advantages regarding lightness and viscosity achieved and confirmed in full-scale production at Munksjö AB Aspa Bruk for more than two years.

Emissions of metal iron complexes Common to all Q-steps is that washed-out complexes of manganese must be removed from the backwater system to prevent excessive levels from building up in the bleaching plant. This must therefore be more or less open with the supply of water free from the manganese complex to the washing filter in the Q-step, because it is the washing water that sets the limit for how low manganese level can be achieved in the pulp into the bleaching step. Thus, backwater must be discharged from the bleaching plant and replaced with water free from manganese complexes, usually fresh water and condensed water. Emissions to the recipient of the complexes naturally encounter environmental problems, as complexing agents are to a limited extent biodegradable and are considered to be able to release heavy metals from bottom sediments. By switching to TCF technology and thus solving the problems with emissions of AOX to the recipient, one has thus instead acquired a 508 227 4 one, albeit smaller, but nevertheless a new problem with the emission of complexing agents to the recipient.

Destruction of metal complexes It would thus be desirable to be able to dispose of the manganese complexes in an environmentally sound manner. One way that has begun to be introduced is to close the system and destroy the manganese complexes in the factory's chemical recycling system with EFM production as the goal.

This means that the drain from the bleaching plant's backwater system instead of going directly to external treatment and. then discharged into the recipient, either directly integrated into the countercurrent with the brown side and then eventually indirectly reaching the chemical recovery, or that it integrates directly with the chemical recovery by transfer to the barrel liquor to evaporator and recovery boiler together with the filtrates from the brown side.

Incrustation Closure of the system in pulp mills in EFM production to eliminate emissions of metal complexes, AOX, COD (i.e. oxygen-consuming organic substance expressed as chemical oxygen demand), and other environmentally harmful substances from the bleaching wastewater and instead transfer this directly to the so-called brown side of the fiber line or directly to the chemical recycling process for destruction, according to the current state of the art encounters encrustation problems, because the backwater in addition to transition metals, at the same time brings with it high levels of other so-called non-process metal ions, commonly referred to as non-process elements (PFG), mainly Ca, Mg, Al, Ba and K, which are desorbed from the pulp by the acidic pH in the Q-stage of bleaching and in any acidic Z-stage, and which together with various anions such as sulphate, phosphate, oxalate, silicate and carbonate, can form sparingly soluble salts and cause problematic incrustations in the form of barium sulphate and calcium oxalate in the bleaching plant, calcium carbonate in the boiler, while in the chemical recovery sodium aluminum silicate silicate in black carbon silicate. the peripheral equipment of the green liquor preparation 598 227 5, such as in pumps and pipelines. The pH reduction in the Q-step must be done in order for the manganese ions to be able to complex efficiently, but at the same time cause an undesired release of fiber-adsorbed calcium and magnesium ion. Through the previously mentioned Hampox-Q process, which utilizes a higher pH level and thus releases less calcium and magnesium ion, the situation can be improved even if incrustation problems can not be ruled out.

Allowing the filtrates from the bleaching plant to go to the barrel liquor in the manner described above and then passing the recovery boiler as well as the filtrates from the brown side, causes. increased crust formation in the evaporators because the acidic filtrates from Q-steps and any Z-steps in the bleaching plant contain high levels of PFG in the form of ions of the previously mentioned Ca, Mg, Al, K and Ba, as well as various anions, e.g. . silicate, phosphate, oxalate, carbonate and sulphate, which can form sparingly soluble salts and are included in the encrustations.

Incrustation can be reduced in the evaporators by allowing the filtrates instead of going to the barrel liquor, to the weak liquor, which goes to the melt solvent and then to the green liquor clarification, where the transition metal ions can be expelled, but then incompletely, because the ligand instead of complete decomposition as in the recovery boiler , undergoes a gradual cleavage with a certain degree of sustained complexing ability in green liquor preparation (melt solution, green liquor clarification), white liquor preparation (causticization, white liquor clarification), impregnation, boiling, emptying, etc., whereby some process-foreign metal ions can be returned to the system and equilibrium level which depends on the ratio in speed between supply and degradation of the complexes in the recovery boiler and other parts of the system.

In summary, according to the current state of the art, if TCF-EFM production is to be avoided in order to avoid building up high levels of non-process metal ions in the bleaching plant (in order to prevent interference from medium anions in the bleaching process, and to reduce calcium and magnesium increments in washing filters and other equipment), then one can choose one of the following three alternatives, all of which, however, have in common that other inconveniences arise instead (a) from the bleacher releasing part of the collected washing filtrates in the bleacher's backwater system to the recipient, with complexing agents included, or to avoid release of complexing agents: (b) transfer the wash filtrates to the brown side by integrating the bleach and thereby destroy the complexing agent in the metal complexes through the recovery boiler, causing crusting problems, or (c) transferring the wash filtrates directly to the chemical solvent dissolver. lie recycling process, as well as causing crustal problems.

In all alternatives, one thus encounters problems. In case (a) environmental problems due to complexing agents in the recipient, in cases (b) and (c) severe crustal problems on the brown side and in the chemical recovery system. It is therefore desirable that the backwater from the bleaching plant has such a low level of controversial complexing agents from an environmental point of view that the backwater can go directly to the factory's external purification and then be discharged into the recipient.

Suggested solutions to the incrustation problem.

The literature describes various ways to internally clean and recycle bleaching liquids in order to rectify the PFG problem, but what they all have in common is that they are not cost-effective for various reasons. One technique is the use of ion exchangers, and another is membrane filtration, but both have in common that ion exchangers and membrane filters are easily contaminated and must be cleaned, and require large maintenance costs and often have to be replaced. These methods have therefore not been given any greater scope in pulp production.

Other methods of carrying out metal ion extractions have been described in our previous Swedish patent applications Nos. 9603858-3 and 9603859-508 227 7 1 entitled "Process for the production of cellulose pulp" and "Process for the manufacture of lignocellulose", respectively. These include metal ion extraction of lignocellulose with an organophilic complexing agent dissolved in an organic solvent, preferably turpentine, under reductive conditions. The requirement for reductive conditions according to these previous patent applications stems from the fact that it has been found that metal ion complexes of transition metals in the higher valence stages at pH values above approx. 8.5 has a tendency to precipitate in aqueous media, the precipitation preferably taking place on the pulp fibers if such are present.

This problem has been addressed and discussed even in our U.S. patent U.S.P. 5.57l, 378, but in that case mainly on the bleaching agent in a new and more efficient Q-step in connection with peroxide bleaching.

To summarize our previous Swedish patent applications Nos. 9603858-3 and 9603859-1, the problem was solved due to the high stability and solubility of the organophilic complexes in the organic solvent; PFG in the form of transition metal ions, but also crust-forming metal ions, such as Ca and Mg, could be efficiently extracted.

THE SOLUTION TO THE PROBLEM The invention.

The problems of the prior art processes have now been solved according to the present invention by metal ion extraction with turpentine oil related extractants in the presence of an oxidizing agent, with or without an organophilic complexing agent. When applied to lignocellulose, more specifically to sulphate pulp, a delignification and a bleaching are obtained simultaneously with the metal ion extraction. The present invention encompasses the following events; complex binding, ion exchange, metal ion extraction and delignification. The turpentine oil related extractants, with or without organophilic complexing agents, are fundamental to the invention. In addition, there is the surprising discovery that the complexes of the transition metal ions in the organic phase under oxidative conditions are stable at significantly higher pH values than previously considered possible.

Our explanatory model for stability is that the oxidation of the transition metal ions to at least one step above their lowest valence stages increases the complex constants by several tens of powers relative to the corresponding complex constants for the metal ions in the lowest valence stages. In aqueous medium, this increased stability competes: however. due to the fact that the solubility of the hydroxides of said metal ions decreases at the same time, so that the hydroxides precipitate already at pH values above approx. 8. This interaction between the solubility product of the hydroxides and the complex constants is expressed as the conditional complex constants of the respective metal ions. According to the explanatory model, these drop dramatically in aqueous medium at a pH above approx. 8, as opposed to in the organic medium, where the hydroxyl ion concentration is low. The explanation model will be developed further later in the tQX.

Within the framework of the concept there is also extraction of anions, i.e. counterions to the above metal ions, which together with the metal ions can form sparingly soluble salts causing crustal problems. The extraction takes place in the same way as in the extraction of metal ions, but by ion pair extraction with an organophilic onium compound, which will be described in more detail below, instead of by complex formation extraction with organophilic complexing agents. Anions that cause crusting problems include carbonate, oxalate and sulphate ions, but the category of anions also includes the metal ion complexes of conventional complexing agents such as NTA, EDTA and DTPA, and these complexes also proved to be able to be extracted over to the organic phase. This means that an organophilic onium compound, which is cationic, can extract metal ions, which are also cationic, said organophilic conventional complexing agents acting as carriers for the metal ions in an unexpectedly well-functioning concept. In this way, the anion extraction alone offers a complete concept for the extraction and control of crust-forming anions and cations (metal ions).

Invention in the sulfate process.

Using the sulphate process as an example, the following describes what happens and what can be achieved in a metal ion extraction with a turpentine oil-related extractant in the presence of an oxidizing agent, with or without an organophilic complexing agent on the brown side in an alkaline environment. By the oxidizing agent is meant that the transition metals are oxidized up at least one step above their lowest valence levels, giving stable organophilic complexes, which in turn catalyze a delignification of the lignocellulose. The exact mechanisms for this are not known, but probable ones will be described later in the text, where it is also explained in more detail why the oxidation of the transition metals gives more stable complexes. Reference may also be made here to our patent U.S. 5.57l, 378, and to: Nordgren, A. and Elofson, A., "New Process for Metal Ion Chelation at Elevated pH in Pulp Production", 1994 Pulpina Conference, TAPPI PRESS, Proceedings Book 3, p. 1321 (1994).

Complex bonding / metal ion extraction of the transition metals (e.g.

Fe and Mn) and the actually crust-forming metal ions (eg Ca, Mg and Ba), m.a.o. PFG already on the brown side means that PFG to a much lesser extent, via the pulp flow, passes over to the complexing (pre-treatment) stage (Q) and the peroxide stage (P) in the bleaching plant. By one significantly smaller amount of PFG reaching the Q-step, the need for complexing agents (EDTA or DTPA) becomes significantly less there and washing out of the complexes formed becomes at a given dilution factor more efficient in the Q-step washing filter before the P-step. The simultaneous delignification frees the lignocellulose from a considerable amount of lignin, which is removed in the form of molecular fragments (COD) already during the metal ion extraction on the brown side, which favors a low peroxide consumption in the bleaching stage of P.

Taking into account and including also an oxygen step (0) and a (less common) ozone step (Z) in addition to the Q and P steps described in the overview above, the complex bonding / metal ion extraction / delignification is performed as early as possible on the brown side in a position already before the oxygen step, so that PFG, in particular Fe, does not reach this to a greater extent and the selectivity is simultaneously liberated has a negative effect. lignocellulose by the combination of complex binding, metal ion extraction and delignification, as previously mentioned, from When thus has more PFG and COD, it becomes less left in to the oxygen step (O), where appropriate to (Z), the oxide step (P) in a considerable amount of COD. extracted and removed from the lignocellulose, the ozone step and, as previously described, to the perisher, the consumption of oxygen, any ozone, and hydrogen peroxide. Which in turn reduces the fact that a much smaller amount of PFG reaches the Q step, as previously mentioned, the need for complexing agents, EDTA or DTPA, becomes significantly less in this. Thereby benefits are gained, both by reducing the need for complexing agents in the Q-step and delignifying in the P-step, which saves both complexing agents and hydrogen peroxide, while environmental benefits are gained by significantly reducing the amount of oxygen-consuming organic matter (COD) and complexing agents (in the form of complex-bound PFG) enters the recipient. Essentially only the smaller amount of oxygen-consuming organic compounds (released lignin and carbohydrates) formed in the bleaching plant then loads the external purification in the form of COD. If you also want to eliminate this load, the bleaching plant's backwater system must also be integrated with the chemical recovery, either directly or in countercurrent via the brown side. Through what has been said above, the invention offers great opportunities for EFM to close the system under conditions.

It is to be understood that the invention is not limited only to the mass production process line to which the brown island side belongs, but also includes other sectors.

In summary, the following applies: (l) the process line for mass production; (2) the chemical recycling cycle; (3) the cooking liquid preparation; in which sectors the extractions can be performed 508 227 ll in at least one position, in at least one of the following steps or steps: (1) (a) chip handling before boiler, (b) pre-impregnation to boiler, (c) boiler, (d) boiler washing zone (continuous technology) or boiler displacement (superbatch technology), (e) deduction before black liquor evaporation, (f) after boilers on the brown side of pulp and on backwater flows, (g) in the bleaching of pulp and in backwater flows, (h) after bleaching , e.g. in combination with paper or board machines; (2) black liquor evaporation; (3) (a) green liquor clearance, or (b) white liquor clearance.

Extract experiments.

According to the present invention, PFG is extracted from lignocellulose by metal ion extraction with or without organophilic complexing agent dissolved in turpentine in the presence of an oxidizing agent, whereby at the same time a delignification takes place. The extraction removes crust-forming PFG and oxygen-consuming organic species (COD) from the lignocellulose, which, as previously pointed out, allows the system to be closed under EFM conditions. Starting from the periodic table, the following substances are the most important for PFG: group I: Na, K, and Cu group II: Ca, Mg, Zn and Ba group III: Al group VI: Cr and Mo, group VII: Mn group VIII, IX and X: Fe, Co and Ni To our surprise it turned out that turpentine as extractant, without organophilic complexing agent, had significant ion exchange capacity for the above PFG. For example, it was found possible that in a one-step extraction with balsamic turpentine of Chinese origin, significant amounts of fiber adsorbed and anhydrous metal ions were extracted from sulfate pulp.

Although much more could be extracted into the organic phase in the presence of organophilic complexing agents, the pure turpentine may in some cases be an alternative or complement to the combination of organic extractant with organophilic complexing agents. The focus here has been on extracting metal ions, but it is obvious that all types of cations can be extracted, e.g. ammonium ions.

Turpentine oils * are one. subgroup of 'plant and tree sap's summarized under the concept of essential oils, in most cases consisting of mixtures of terpene and sesquiterpene compounds with a smaller proportion of compounds from other classes of compounds. A second larger group consists largely of aromatic compounds including phenols. The concept of essential oils also includes eucalyptus oils, sassafras oil and camphor oil, of which eucalyptus oils in particular are interesting as extraction agents in the pulp industry as eucalyptus wood is an important raw material for pulp production.

Turpentine oil is the collective name for the volatile constituents in raw resins from in particular pinus species of various conifers, referred to as "turpentine" or "balsam". Depending on the starting material and production method, a distinction is made according to DIN 53248 (April 1977) between, for example: balsamic turpentine oil; by extraction and / or steam distillation purified rat pentin oil; crude and purified sulphate pentine oil; sulfite pentine oil; purified (distilled) wood tar, etc ..

The main constituents of turpentine oils are mono- and bicyclic monoterpenes Cm fl m; in addition, there are minor amounts of terpene-oxygen compounds (eg, terpene alcohols), sesquiterpenes, and other compounds; the composition depends on the pinus species turpentine oil is extracted from, but the main component is in most cases the alpha-pinene with decreasing amounts of beta-pinene, camphene, 3-karen and limonene in that order. 0 Eg. Swedish sulphate pentine may contain: 50-75 s alpha-pinene; O 4-7% beta-pinene; l% camphor; 15-40% 3-car; 1-3 a limonene, and 508 227 13 ha a boiling point range of 150-l75 ° C at 1013 mbar. Turpentine oil of Chinese origin, which has been used in the experiments, may consist of: 60-92% alpha-pinene; 4-9% beta-pinene; 1-2% camphene; 0-10% 3- karen; 1-3% limonene, and have a boiling point range of 150-160 ° C at 1013 mbar.

In addition to the above ingredients, turpentine oil may contain alpha- and gamma-terpine, alpha- and beta-phellandren, terpinol, myrcene, β-cymol, bornyl acetate, anethole, sesquiterpene, heptane, nonane and several other compounds such as abietic acids, palimic acids, palimic acids which are derivatives of tricyclic terpenes. They belong to the group of natural resin acids and are the main constituent of various rosin resins. These are obtained as distillation residue in distillation of turpentine balsam extracted from various pine species, as well as in distillation of pine oil, where even a small proportion of fatty acids are included in the pine resin, while a third type of rosin is obtained by solvent extraction of root pieces (töre) and is called root resins. The group of synthetic resin acids includes compounds such as modified hydrocarbon, acetophenone and polyamide resins.

Sulphite pentine differs significantly from the other turpentine oils in that it contains as much as 70-90% β-cymol and minor amounts of borneol, dipentene and sesquiterpene.

The higher fraction. of distilled wood tar, so-called natural "pineoil", may have the following composition: 50-70% alpha-terpineol; 5-10% borneol (and isoborneol); 5-10% fenchol; 5-15% other turpentine alcohols (p-mentanol-8, beta-terpineol, turpin, etc.); 0-10% terpinyl and boronyl acetate; 0-3% monoterpenes (pinene, dipenten, terpinols, etc.); 5-10% other ingredients (cineoles, camphor, anethole, tarragol, sesquiterpenes, etc.).

Synthetic: "pineoil", produced by thorough hydration of alpha-pinene-rich turpentine oil fractions, may have the following composition: 50-95% alpha- and gamma-terpineol; 3-20% other no 508 227 14 terpene alcohols (beta-terpineol, terpinen-1-ol, fenchol, etc.); O-30% terpenes (3-carene, turpins, dipents, terpinols, etc.); 1-10% 1,4- and 1,8-cineole.

The chemical properties of turpentine oils depend on the constituent components, of which, for example, the pin is reactive in the presence of acids, acid salts, surfactants or Friedel-Crafts catalysts and they can form hydrates in the presence of water. It is quite conceivable that certain reactions take place during the extraction which change the chemical and physical properties of the extractant, but then the reaction products and the new properties of the extractant are also included in the idea and scope of the invention.

General test methods for characterization of turpentine oils are summarized in DIN 53248 (April 1977) and largely comply with international standards in ISO 412-1976.

Determination of individual components can be done by gas chromatography according to DIN 51405 or ASTM E 260-69. Quantitative analysis of resin acids in rosin resins can be performed according to ASTM D 1585-63 and ASTM D 1240-54.

It is understood that the above-mentioned turpentine oils or their derivatives included in the concept of essential oils are only examples and that other compounds or their derivatives which are included under the same concept can also be used individually or included as components. The same applies to turpentine substitutes such as e.g. decalin and tetralin; the hydrogenation product closely related to turpentine oil hydroterpine (monocyclic monoterpenes; boiling range 180-195 ° C); distillation and rearing products from turpentine oil, or other synthetically produced synthetic turpentine oils or their derivatives.

Furthermore, compounds with dissociable hydrogen ions of, for example, phenolic character, such as e.g. β-cymol may be included. Others may be of the thiophenol character, such as e.g. lignotiols formed in the cooking step of the sulphate process, while still others may be of a carboxylic acid character, e.g. tall oil fatty acids containing e.g. fatty acids and resin acids, which can be taken up and dissolved in the turpentine. Other acids, such as lignosulfonic acids and lignocarboxylic acids, can be formed in the oxygen step of the sulfate process by oxidation of lignothiol and lignin fragments, respectively. In the sulfite process, lignosulfonic acids can be formed directly in the boiling step by sulfonating lignin fragments. Preferred extractants according to the invention are balsam, sulphate and sulphite turpentine, which do not have to be in purified form, but can be rater spirits. The water vapor that is gassed off from the top of the cooker during the sulphate and sulphite cooking process contains the raterin. The vapors are condensed and the condensate is led to a decanter and the raterpentine is separated off as supernatant. By oxidizing treatment and distillation, the raterpentine can be purified.

The above data for turpentine oils and resin acids are taken mainly from Ullmann's Encyclopedia of Technical Chemistry 4, newly edited and expanded edition volume 22, chapters Terpene and turpentine oil, and volume 20, chapter Rich and aromatic substances, respectively volume 12, chapters.

Table 1 below shows extraction tests on lignocellulose, more specifically sulphate pulp in the presence of air at a pulp consistency of 5% based on the aqueous phase, at the weight ratio water / turpentine "1/1 and at a temperature of 60-70 ° C. Comparative studies have been made between turpentine in combination with organophilic complexing agent, the aromatic hydrocarbon toluene in combination with organophilic complexing agent and turpentine alone. All extractions are single-step extractions. The sulphate mass contained 7 mg Fe, 251 mg Mn, 203 mg Mg and 1596 mg Ca / kg dry-think. The organophilic complexing agent used was N, N-bis (2-hydroxy-5-nonylbenzyl) glycine stoichiometric amount. The balsamic turpentine used in our experiments had the following main composition: 84% alpha-pinene; 8% beta-pinene ; 1.5% limonene; 1.5% bicyclic sesquiterpene; less than 1% menthyl acetate 508 227 16 Table 1. Extracted to organic phase (%) Metal ion extraction of sulphate pulp pH Fe Mn Mg Ca Te rpentin + Organophilic complexing agent 7.5 82 93 70 88 8.5 81 89 85 81 9.5 83 80 73 80 Toluene + Organophilic complexing agent 7.5 81 18 88 91 8.5 85 17 85 84 9.5 83 25 89 84 Turpentine 7.5 75 75 17 53 8.5 84 80 46 60 9.5 80 81 55 80 According to the state of the art, lignocellulosic properties of ion exchangers in the sulphate process compete so much with the water-soluble complexing agents EDTA and DTPA in aqueous medium at higher pH, that it normally it is not possible in practice to carry out a complex bond at pH above 6. It was therefore surprising when we, as the table shows, found that with turpentine, with or without organophilic complexing agents, it was quite possible to efficiently extract the metal ions over the entire pH range. As can be seen from the table, toluene also worked well in combination with organophilic complexing agents, with a high percentage of extracted metal ions.

The extraction process could easily be followed by developing the color from the complexes with transition metal ions, which will be described in more detail later in the text.

One reason for the strong competition from lignocellulose is considered to be 4-O-methylglucuronic acid substituents on the hemicellulose xylan, which in the cooking process by elimination of a methoxy group and rearrangement are converted to 4-deoxyhex-4-euronic acid substituents (Hex-A), which form as strong can bind metal ions and thus act as an ion exchanger.

[T. Vuorinen, J. Buchert, J. Teleman, M. Tenkanen, P. Fagerström, 17 '"Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps", International Pulp Bleaching Conference Proceedings, Washington, USA (1996), p. 431.

Another reason for strong competition from the lignocellulose may be that transition metal ions bind to thiol groups formed by substitution on the lignin component at the high sulfidity of the boiling step; this according to a hypothesis we presented in our patent U.S. 5,571,378 (USP Appl. Serial No. 08 / 327,999) "Process for high-pH metal ion chelation in pulps" (Hampox-Q) for metal ion control on the bleaching side. According to the patent and in support of the hypothesis, zero levels of manganese can be achieved by oxidation in the presence of DTPA, whereby as part of the explanatory model it was stated that lignothiol groups are oxidized to lignosulfonic acid groups leading to weaker bonds to transition metal ions whereby DTPA is able to complex the metal ions.The hypothesis is further supported by the experience that fiber adsorbed manganese reduces oxidation. may be that lignotiol groups are oxidized to lignosulfonic acid groups and that lignotiol fragments or lignosulfonic acid fragments in the form of manganese complexes or manganese salts, which were previously part of the lignocellulosan, are cleaved off and go into solution during delignification.

In addition to the ions reported in the table, Al (80%), Si (50%), K (10%) and others were also extracted. It is surprising that Si and Al were extracted when they are present as silicate and aluminate ions at the current pH range. The cause is not clear, but organophilic ammonium ions may play a role as carriers to the organic phase. This is discussed in more detail later in the text.

Table 2 below shows one-step extraction experiments with turpentine and toluene, respectively, on aqueous phase only without lignocellulose. The table shows the results both with and without organophilic complexing agents in the organic phases. In these cases, therefore, no mass has been included in the experiments, but the extractions have been made only between the aqueous phase and the organic phase consisting of the respective organic extractants. The weight ratio of aqueous phase to organic phase was 1/1 and the temperature in the experiments was 60-70 ° C. Prior to extraction, 139 mg of Fe, 137 mg of Mn, 61 mg of Mg and 501 mg of Ca / l were dissolved as metal salts in the aqueous phase.

Table 2. Extracted to organic phase (%) Metallic ion extraction of aqueous phase pH Fe Mn Mg Ca Turpentine + Organophilic complexing agent 7.5 85 100 11 49 8.5 85 100 61 86 9.5 78 95 72 90 Toluene + Organophilic complexing agent 7.5 78 63 4 22 8.5 85 88 6 33 9.5 85 88 18 53 Turpentine 7.5 53 80 5 10 8.5 40 80 9 20 9.5 55 80 26 63 Toluene 7.5 1 0 1 8.5 1 0 1, 1 0 Table 2 shows that toluene alone practically did not extract the metal ions at all, while turpentine functioned well as an organic solvent for the metal ions. Together with organophilic complexing agents, toluene compared with turpentine worked relatively well as a solvent for the complexes of Fe and Mn, but did not reach the level of turpentine for Mg and Ca. at all. The absence of lignocellulose clearly shows, in comparison with Table 1, a clear increase in extracted Mg and Ca at increased pH in all cases except for pure toluene, in which the solubility is too low for an assessment. This tendency is also present for Fe and Mn, but less pronounced.

In similar experiments as in Table 2 but in the presence of stoichiometric amount of DTPA, DTPA was outcompeted by the organophilic complexing agent in turpentine so that the majority of the metal ions were extracted over to the organic phase in the high pH range as in the experiments of Table 2. This was unexpected and surprising because DTPA is the most effective complexing agent of its kind, and it can be interpreted as a synergism between turpentine and organophilic complexing agents, as both organophilic complexing agents in toluene and only turpentine gave only an insignificant metal ion extraction in the presence of DTPA. In the case of turpentine alone, the result thus differs from that in Table 2, where the metal ion extraction was significant; a difference which is thus an effect of DTPA. The metal ion extraction with toluene alone was barely detectable both in the presence and absence of DTPA.

During the extraction, as previously mentioned, the organic phases underwent a characteristic color shift from colorless to pale orange over purple to finally a brownish hue, indicating an oxidation by air oxygen of the organophilic Fe (II) and Mn (II) complex to higher valence levels. ; to Fe (III) and at least Mn (III), perhaps Mn (IV). These complexes have been shown to be stable in the organic medium, as evidenced by the presence of their characteristic color even at pH 11.5-12. It can be assumed that it is the specific chemical-physical environment in the organic medium that conditions the stability, since e.g. The EDTA or DTPA complexes with manganese in their higher valence levels are not stable in aqueous medium at such high pH, but as previously mentioned are outcompeted by lignocellulose modified in the boiling process or precipitate as oxide hydrates already at pH above 6.

It was therefore surprising when we found that the complexes of the transition metals.in the.organic phase.in oxidative conditions were stable at significantly higher pH values than previously considered possible. The oxidation of the transition metal ions to valences one step above their lowest increases the complex constants by several tens of powers. According to what we have found in our studies, this can be utilized up to pH 11.5-12, when otherwise so weak complexes are formed that oxide hydrates begin to precipitate or the competition from the present fiber phase, which as previously mentioned also functions as an ion exchanger, leads to fiber adsorption. At pH above 11.5-12, the benefits of reductive conditions according to our two previous patent applications outweigh the extraction under reductive conditions to get over the transition metal ions to the lower valence levels outweigh.

Thus, by the present invention, a well-known problem in sulphate pulp production has been solved, namely, to be able to efficiently complex bond transition metals such as Mn (III) and Fe (III) in the form of stable complexes at high pH, as mentioned up to pH 11.5-12.

The problem of not being able to effectively complex and remove these metal ions in oxidative environments, i.e. on the brown side after the silage, fr. if. the oxygen step where high pH prevails, has thus been given a surprising solution. Basic, as stated above, is the extraction with organic solvents, preferably turpentine oils, in which due to the high stability and solubility of the complexes, PFG in the form of transition metal ions, but also crust-forming metal ions, such as e.g. Ca and Mg, could be efficiently extracted. Organic solvents in general, but terpenes in particular, in combination. with organophilic complexing agents further increases these possibilities.

The logical but surprising conclusion of the foregoing is, as previously mentioned, that the complexes in the organic solvent are more stable and outcompete complexing agents such as EDTA and DTPA, but also the hexenuronic acid and / or the lignotiols in the lignocellulose modified in the cooking process up to pH 11.5. 12; in the case of hexenuronic acid, in that it is cleaved by oxidative hydrolysis and rearranged into other species during the extraction, and / or in that the complexes in the organic solvent are more stable than t.o.m. the hexenuronic acid; in the case of the lignotiols, by oxidizing them to lignosulfonic acids and / or by cleaving lignotiols and lignosulfonic acids as part of the delignification process during the extraction and / or by making the complexes of the organic solvent more stable than the complexes of the lignotiols and lignosulfonates, respectively. Regardless of the situation, this is innovative because the problem of metal ion affinity for lignocellulose according to the prior art has so far only been solved by hydrolysis at low pH (about 3) and high temperature (about 90 ° C), or by strongly acid oxidative bleaching / delignification with ozone or chlorine dioxide.

The present invention complements our previous Swedish patent applications Nos. 9603858-3 and 9603859-1 regarding the use of organophilic complexing agents. In the present invention the limit case is that the dosage of complexing agent can go towards zero, while in the previous two this could never be the case as the organic solvent was not assumed to have any complexing capacity and the dosage must therefore always have a value greater than zero. This was before the complex-forming capacity of turpentine was discovered and the difference between turpentine and e.g. toluene in that respect clarified. The present invention and. our previous two therefore complement each other in a comprehensive way and together provide great opportunities to cope with the metal ion control in mass production under ECF conditions.

Complex bonding under oxidative conditions has admittedly been addressed and discussed in our U.S. patent, U.S.P. 5.57l, 378, but then mainly on the bleaching side in a new and more efficient Q-step in connection with peroxide bleaching.

In summary, the experiments presented in Table I show the ability of turpentine, with and without organophilic complexing agents, to extract metal ions from solid phase to liquid phase, i.e. in this case extraction of strongly fiber adsorbed metal ions from a sulphate mass to organic phase. Here, turpentine together with an organophilic complexing agent is best, but only turpentine has a not insignificant potential.

In Table 2 organic, toluene is compared with turpentine. The table shows the ability of these solvents, with and without organophilic complexing agents, to extract metal ions from one liquid phase to another, i.e. in the exemplified cases from aqueous phase to organic phase. Without organophilic complexing agents, turpentine is completely superior to toluene, which without organophilic complexing agents practically does not dissolve any metal ions at all, while turpentine does relatively well without the organophilic complexing agent. The extractions in the examples have been done in one step, but it is understood that any number of steps can be used.

The explanation for the ion exchange properties of turpentine may be its content of organic compounds with substituents in the form of groups of phenolic groups and hydroxyl groups manifested in a considerable functional such as e.g. carboxylic acid groups, buffer capacity for alkalis. Thus, upon titration with sodium hydroxide in aqueous medium, a buffer capacity corresponding to 8 meq / kg up to pH 8.5 and 30 meq / kg up to pH 11 was obtained, with maximum buffer capacities, i.e. pK; values, at about 7 and 10, respectively, and values in between, corresponding to the presence of functional groups with an acid character, such as e.g. the above.

Possible compounds with functional groups of an acid nature could be natural and synthetic resin acids, fatty acids and monohydric, dihydric and trihydric phenols. One hypothesis is that said groups can form complexes through bonds to metal ions of a covalent and / or electrostatic nature, but also form salts. carboxylic acid salts, by ionic bonds. complex binding is that the bond-mediating atom in the functional group has a free electron pair.

Such atoms may be e.g. 0, N or S. Possibly some components containing double bonds can also form stable so-called pi complexes with transition metals which, if present in aromatic properties, could also yield sandwich-type pi complexes.

Other explanations may exist, but without being bound to these and regardless of the underlying mechanisms, turpentine acts as a high-capacity ion exchanger. The great advantages over conventional ion exchangers in granular form when it comes to pulp production lie in the possibility of extracting not only liquid phase, e.g. filtered on a fiber line, but also solid phase, e.g. pulp fibers in a washing machine. It follows that they also, unlike ion exchangers in granular form, function without interference in the presence of particulate contaminants. However, the liquid ion exchangers are not limited to mass production only, but can generally be used in applications where there is a need to transfer metal ions from one system to another.

Such applications may be the recovery of metal ions from various wastewater, e.g. from surface treatments such as for cleaning, pickling, corrosion protection treatment or from baths for plating metal surfaces such as electrolytic or chemical baths for e.g. copper, nickel, chromium, silver, gold, platinum or other plating, film-developing badziphoto laboratories, or in general where you want to recycle valuable metal ions, or want to prevent ions of e.g. heavy metals come out in the recipient. Simultaneously with the metal ions, organic substances are also extracted, which may be unsuitable for release into a recipient due to toxicity or consumption of oxygen; it can be in industry, but it can also apply to municipal activities, e.g. municipal purification.

Composition of the extractants In experiments with vacuum-distilled turpentine, the distillate showed no cationic activity, while the distillation residue (3.5%) showed a high one, which has been shown experimentally in experiments analogous to those described above, see Table 2. This supports the hypothesis presented above. , that there are smaller amounts of specific components in the turpentine that condition the cationic activity. These components may consist of resin acids, fatty acids and monohydric, dihydric and trihydric phenols, as mentioned and described above. By dissolving the distillation residue or one or more of its components in an optional organic solvent in any concentration, suitably highly concentrated, it is possible to compose an extractant for each specific purpose.

After identification of the components, it is also possible to synthesize them and then in the same way compose an extractant for each specific purpose. In this case, it is possible to start from various natural or synthetic resins, such as rosin resins and modified synthetic resins, respectively. This offers great potential for improving the above-identified probable synergism of the enanophilic complexing agent and the extractant.

More precisely described, the extractant may be turpentine or a compound or a mixture of different compounds, at least one of these compounds having properties as turpentine while others may be inactive or less active as ion exchangers and mainly serve as organic solvents for organic substances present in the system. By definition, the extractant must have limited solubility in water and vice versa, which means that the inactive organic solvent does not have to be insoluble in water, but can consist of e.g. butanol or other alcohols, which, however, must not be included in such a quantity that extraction is prevented by the extractant becoming too soluble in the aqueous phase or in the medium constituting the second phase. Furthermore, the extractant may include substances present in the backwater systems of pulp mills as a result of wood treatment in the manufacturing process, such as alcohols including fatty alcohols, carboxylic acids including fatty acids, mono- or polyfunctional phenols and their derivatives, thiols, thiophenols, sulfonic acids and hemuluric acid products. and hexenuronic acid, lignin hydrolysis products such as hydroxyphenylpropane derivatives and lignin and hydrolysis fragments. derivatives thereof such as lignotiols, turpentine oils specific for the wood and the manufacturing process, etc., as previously described in more detail. In order to obtain the desired properties of the extractant and to e.g. To increase its cation exchange capacity, it is possible to dissolve one or more cationic (anionic) organic compounds in a limited water-soluble organic solvent. The cationic organic compounds can e.g. be one or more of the above-mentioned substances present in the backwater system of the pulp mill or optionally other cationic active compounds, such as various resin acids of origin mentioned above.

As a working hypothesis, it was assumed that if, on the other hand, an extractant is composed by dissolving an organophilic anionic (cationic) compound in a substantially water-insoluble organic solvent, anions could be extracted with the extractant thus composed. Among the anions, i.a. oxalate, sulphate, aluminate, silicate, phosphate and carbonate ions to the crustal problems by forming counterions to e.g. Ca, Mg, Al and Ba ions while chloride ions increase the corrosion problems at the closure of a pulp mill during the so-called EFM (effluent free mill) conditions. It is therefore desirable under these conditions, but also in general, that e.g. in the sulfate or sulfite process.reduce the loading of these ions.

Since hydrophilic (water-soluble) conventional complexing agents, such as e.g. EDTA or DTPA, are also anions both as free ligands (which in themselves can not exist as in the presence of metal ions in a pulp mill) and as metal ion complexes, it was assumed t.o.m. that it would be possible to extract to the organic phase over these complexes in the form of ion pairs by means of the organophilic anionic (cationic) compound. We were able to confirm this experimentally, which will be reported later in the text.

Such an extraction according to the invention means increased possibilities for the disposal of also water-soluble complexing agents of the conventional type as well as the complexed metal ions from, above all, a peroxide bleaching backwater system for reprocessing in a separate system separate from the factory's cooking chemical recovery system. As a result, backwater with metal ion complexes from the Q-stage bleaching plant's Q stage does not need to be returned to the factory's cooking chemical recovery system, where crust-forming metal ions can cause problems in a known way, or alternatively no discharge of metal complexes to the recipient needs to be made where the metal ion complexes can cause environmental problems.

The organophilic anionic (cationic) compounds may be organophilic homologues of various onium salts such as ammonium, sulfonium, oxonium, phosphonium salts etc. with organic substituents on the respective functional onium atom (respectively N, S, O, P etc), which at full number of substituents are stable and appear as cationic (positive) onium ions over the entire pH range, as well as corresponding homologues of amines, sulphines, oxins and phosphines, which can be converted to onium salts by proton transfer.

Preferred onium salts are organophilic quaternary alkylammonium salts, among which quaternary homologues such as N, N, N, N-tetraalkylammonium bases (R% ÜRïÜNOH) are preferred and among which those having 4-22 carbon atoms in at least one alkyl substituent and each 1-4 in the other three the substituents are most preferred, one example being N-dodecyl-N, N, N-trimethylammonium hydroxide having twelve carbon atoms in one alkyl substituent and each having a carbon atom in the other three substituents, and another example tetrabutylammonium hydroxide having 4 carbon atoms in all alkyl substituents. The motion (anion) of the various onium salts must be other than the anion to be extracted and is preferably a hydroxyl ion. Regeneration to hydroxifornx can be done analogously to that described for the organophilic complexing agents under the heading "Detailed Description of the Invention", but by extraction with alkaline instead of acidic aqueous solution.

Unlike the quaternary ammonium compounds, the primary, secondary and tertiary amines are neutral and become cationic ammonium ions only upon protonation in some protic medium, e.g. in the protolyte and ampholyte water or in a protic organic medium, which like water, can act as a proton donor (acid), such as e.g. components in turpentine.

The pKa value of the amine in question corresponds to the point on the pH scale when half of the amine has been protonated, while complete protonation corresponds to the neutralization point of the amine, which is lower than the pIg value; how much depends on the concentration of the amine in question in the medium in question. The pKa value of the amine is dependent on e.g. the protolytic properties of the medium such as its protolysis or acid constant, which for water is 14.00 at 25 ° C. Other media have other protolysis constants, higher or lower than 14. As guideline values for pKa values of aliphatic amines in water, approx. 10-11, ie in aqueous medium, the pH must be lower for a cationic ammonium compound to be present.

Similar pKa values also apply to many aminocarboxylic acids. Thus, the oligomeric organophilic complexing agent used in our experiments as aminocarboxylic acid can also be converted to ammonium carboxylic acid by protonation and as an anionic (cationic) ammonium compound extract the above-mentioned chloride and sulphate ions, as well as hydrophilic (water-soluble) complexing agents, such as EDTA and DTPA, in the form of ion pairs to the organic phase. The condition is that the pH value in this is lower than the pKa value for the ammonium form of the organophilic complexing agent in the organic phase, e.g. a turpentine with mainly alpha-pinene. This pH value depends on the pH value of the aqueous phase.

In addition to the aforementioned organophilic anionic (cationic) onium ions (eg R1, R2, R3, R 'N'), the extractant may at the same time contain organophilic cationic (anionic) species (e.g.

R5COO ') and / or organophilic complexing agents (anionic, eg R ° L "') and / or their metal ion complexes (also anionic, eg R7LM" "), (where RI, Rz, R3, R °, R 5, R 5 and R 7 are alkyl groups, L is ligand and M is complexed metal ion), but then it can be expected that organophilic anionic (cationic ammonium ions (R 1, R 2, R 3, R 4 N *) 508 227 28 will form ion pairs with cationic (anionic) species (E9COO '), wherein anionic and cationic species mutually inactivate each other and prevent cations and anions in the aqueous phase from being extracted over to the organic phase, therefore this is not a preferred form of application.

This also applies to the organophilic complexing agents (anionic, R9L ”) and / or their metal ion complexes (also anionic, IÛLM”), but since they may exist or exist as metal ion complexes and not as metal salts, they are not inactivated to form ion pairs.

The same applies to complexing components belonging to the organic solvent.

In the case of the conventional hydrophilic (water-soluble) complexing agents, such as EDTA or DTPA which are also anionic, the formation of ion pairs with an organophilic anionic (cationic) onium compound (R1, RÄEÜ, R¶W) t.o.m. be desirable; the latter can thereby transfer metal ion complexes (anionic) from the aqueous phase to the organic phase and act as carriers and free the aqueous phase from both metal ions and complexing agents. That this happens has been shown experimentally in experiments analogous to those reported above, but using N-octadecyl-N, N, N-trimethylammonium chloride.

The water-soluble complexing agents can be selected from glycine, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEEDTA) monomethylphenomepa , N-bis (2-hydroxy-5-sulfobenzyl) glycine, N, N-bis (2-hydroxy-5-alkylbenzyl) glycine, N, N-bis (2-hydroxy-5-carboxybenzyl) glycine or mixtures thereof.

Delianifierina in connection with metal ion extraction.

In connection with the extraction of sulphate pulp during the supply of atmospheric oxygen, to our surprise, a considerable delignification of the pulp was obtained, measured as kappa number reduction. This was also the case in the presence of hydrogen peroxide. It can be assumed that certain metal ion complexes can function as catalysts for oxidation of lignin, and it is understood that an oxidation and thereby a delignification can also be effected with a number of oxidizing agents such as e.g. oxygen, ozone, hydrogen peroxide or peroxyacids, such as peroxyacetic acid, peroxyoxalic acid, peroxybenzoic acid, peroxysulfuric acid and their salts or other peroxides such as benzoyl peroxide. Preferred oxidizing agents are atmospheric oxygen, oxygen, hydrogen peroxide and peroxyacetic acid. Possibly part of the kappa number reduction can be attributed to oxidative hydrolysis of hexenuronic acid groups on the hemicellulose. Such a hypothesis can be substantiated by the fact that the organophilic complexing agents in turpentine easily outcompete lignocellulose as strong ion exchangers, as previously reported and discussed.

The characteristic color of the organophilic metal ion complexes in the organic solvent indicates the presence of transition metals, eg Fe and Mn, in their higher valence stages, which may indicate catalytic activity for them. Optionally, they may also exist as organophilic salts in the form of catalytically active ion pairs. The high degree of delignification under the present mild conditions of low temperature and low pH, can possibly be explained by the fact that the reactions take place and are catalyzed in the organic solvent phase and / or in its boundary layer. Other explanations may exist, but without being bound to these and regardless of the underlying mechanisms, it is obtained according to the invention. a significant reduction in kappa number at the same time as the metal ions in the pulp are extracted out in an efficient manner and removed from the system, which prevents crust formation.

Iabell_§ shows delignification, viscosity and brightness during extraction of sulphate pulp in the presence of hydrogen peroxide. With the help of the mentioned analysis values, a picture is given of what happens to the mass after metal ion extraction with organophilic complexing agents in turpentine, compared with extraction with only turpentine and before extraction. The sulphate mass contained 7 mg Fe, 160 mg Mn, 237 mg Mg and 1574 mg Ca / kg dry solid mass at 12% pulp concentration. As organophilic complexing agent, N, N-bis (2-hydroxy-5-nonylbenzyl) glycine was used in stoichiometric amount. The conditions were the same as in the experiments presented in Table 1.

Table 3. pH Kappa “viscosity N Brightness Ü ml 0, lN mPa.s (cp)% ISO KMn04 Terp. + Organophilic 7.5 19.2 50.3 33.6 complexing agent 8.5 18.4 49.9 36 , 2 9.5 17.5 42.6 36.9 10.5 17.6 46.8 36.9 11.5 18.3 41.8 36.7 Turpentine 7.5 18.4 38.6 33, 1 8.5 17.4 27.9 36.3 9.5 15.7 34.0 37.7 10.5 16.4 34.7 36.8 11.5 15.7 28.5 36.9 Before extraction 20.0 56.0 25.5 a) TAPPI T 236 cm-85. b) TAPPI T 230 om-82 (viscometers: Haake; n = 64 and Cannon-Fenske). c) SCAN P 3:75.

The kappa number is a measure of the degree of delignification and the table shows a kappa number reduction that increases with pH as expected. It is possible that part of the kappa number reduction compared to the reference can be attributed to turpentine extraction of water-insoluble fiber adsorbed organic substance. Sonuen interesting circumstance and important to note is that the viscosity losses were significantly lower in the presence of organophilic complexing agents.

The candles have also been included in the table. Here too one can see 508 227 31 a pH dependence through an increase as a function of pH.

Table 4 shows extraction experiments without hydrogen peroxide, but in the presence of atmospheric oxygen. The reduction in kappa number shows that delignification is also achieved with atmospheric oxygen. In this case, the same starting mass was used as during the experiments presented in Table 1 and except that the weight ratio of water / turpentine was 2/1, the conditions were otherwise the same.

Table 4. pH Kappa Ü viscosity M Lightness “ml 0.1N mPa.s (cp)% ISO KMnO, Terp. + Organophil 8.5 17.8 53.3 29.1 complex image. 9.5 18.8 54.2 30.6 10.5 19.9 51.1 28.8 Turpentine 8.5 22.1 38.0 34.6 9.5 18.9 47.9 29.3 10 18.9 48.3 28.7 Before extraction 22.3 56.9 27.0 a) TAPPI T 236 cm-85. b) TAPPI T 230 om-82 (viscometers: Haake; n = 64 and Cannon-Fenske). c) SCAN P 3:75.

Delignification according to the invention can be a complement to a conventional oxygen delignification and can provide an opportunity to increase the kappa number reduction without losing viscosity in the oxygen step, i.e. increase the selectivity of this. It could also increase the flexibility of the zinc process. These possibilities could make it more cost-effective to produce TCF pulps in competition with ECF pulps. As can be seen from the tables, the extraction conditions are decisive for the selectivity, i.e. viscosity losses, and the lowest losses are obtained in the presence of organophilic complexing agents. 508 227 32 It is understood that these examples are shown for illustrative purposes only and that modifications may be made to e.g. oxidizing agents, textures, solvents, amount of solvent, temperatures, reaction time, pH, etc., without departing from the spirit and scope of the invention.

As a result, there is considerable scope for influencing the result in the desired direction and it is thus possible to vary the selectivity and degree of delignification within wide limits.

For example. reaction time, temperature and pressure can be varied within wide limits by selecting extraction and reactor equipment. You can t.o.m. envisage carrying out the reaction (delignification) in a separate reactor independent of the extraction, as a reinforcement or equivalent to an oxygen or peroxide step, or as an oxidizing process in organic solvent directly on the wood (chips) for delignification of lignocellulose, which a reinforcement to, or even as the primary delignification step corresponding to existing cooking processes, e.g. the sulphate or sulphite process. If the aim is only metal ion extraction and the influence of the chromophores in the lignin for increased brightness, which is desirable in the case of mechanical masses, there is room for selection of suitable conditions for this as well. If the oxidizing agent is e.g. atmospheric oxygen may be the atmospheric oxygen present in the process, or the same may be supplied in some controlled manner.

Reductive conditions In the case of mechanical, chemical-mechanical or semi-chemical pulps, conventional oxidative and reductive methods are used in conventional bleaching of these according to the state of the art, e.g. with hydrogen peroxide and with sodium dithionite respectively, with only one or with the other method or with both methods in combination.

The bleaching method according to the invention can be combined with the methods according to the prior art, in order thus to give an enhanced bleaching and to make it more selective by extraction of PFG, in particular Mn. 508 227 33 In this case, but also in general, it is according to the present invention possible to use a reducing agent instead of an oxidizing agent in metal ion extraction with only turpentine oils, in the same way as described in our two previous Swedish patent applications Nos. 9603858-3 and 9603859. -1, where it involved metal ion extraction with an optional organic solvent in combination with an organophilic complexing agent. During metal ion extraction in the presence of a reducing agent, the complexes of transition metal ions are reduced, e.g. iron and manganese, to their lower 'valence levels and. extracted together with other categories of metal ions, e.g. calcium, magnesium and barium.

The reducing agent, or a combination of reducing agents, may be selected from hydrogen sulfide, sulfide, sulfur dioxide, hydrogen sulfite, sulfite borohydride, ditionite, tetrationite, thiosulfate, hypophosphite, orthophosphite, etc. wherein the counterion to the anions in the mentioned examples may belong to e.g. the groups alkali or alkaline earth metals, usually sodium, magnesium and calcium; for example sodium dithionite is a particularly suitable reducing agent.

Or n fil k m l x ildare The organophilic complexing agent, i.e. a complexing agent with one or more lipophilic groups or substituents, may be selected e.g. from organophilic derivatives of aminocarboxylic acids, hydroxialkylaminokarboxylsyror, hydroxy carboxylic acids, aminophosphonic acids, phosphonic acids, hydroxibensylaminokarboxylsyror, hydroxialkylbensylaminokarboxylsyror, hydroxisulfobensyl- aminocarboxylic hydroxikarboxibensylaminokarboxylsyroreller mixtures thereof, wherein the substituents can include such groups as e.g. .: mättade- or unsaturated fatty acid groups (acyl groups); saturated or unsaturated sulfonyl groups; saturated or unsaturated aliphatic hydrocarbon groups such as e.g. alkyl, alkenyl or alkynyl groups; substituted or unsubstituted, saturated or unsaturated alicyclic hydrocarbon groups such as e.g. cyclohexyl and alkylcyclohexyl groups; substituted or unsubstituted aromatic hydrocarbon groups such as e.g. nonylphenol groups, including their nonyl group isomers, etc., wherein the bonds between substituents and substrates may be e.g. of the types C-N, C-O, C-C, C-S, S-N, S-O, S-C, S-S.

Examples of suitable organophilic complexing agents are organophilic derivatives of glycine, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethyltyrilic acid, hydrochloride; HEEDTA), diethylenetriamine pentamethylenephosphonic acid (DTPMPA), monomeric or oligomeric formeranzN, N-bis (2-hydroxy-5-sulfobenzyl) glycine, N, N-bis (2-hydroxy-5-alkylbenzyl) glycine, N, N -bis (2-hydroxy-5-carboxybenzyl) glycine or mixtures thereof.

In the limit case when extraction with only turpentine-related ion exchanger according to the invention, the lower limit for dosing of organophilic complexing agents is by definition zero. The upper limit is calculated according to the amount of metal ions in the mass and according to the requirements for low metal ion levels. For example, at the levels of PFG that may be present in sulfate pulp, a one-step laboratory-scale extraction with a stoichiometric amount of organophilic complexing agent reduced the amount of fiber adsorbed Mn, Ca and Mg according to Table 1. However, when complexing agents are recovered and recycled after complex make-up for , this amount is not the same as the consumption of organophilic complexing agents, but the consumption can be one tenth of the dosage.

DETAILED DESCRIPTION OF THE INVENTION Preferably applied in the sulphate process, the extraction is carried out in at least one position in at least one step, preferably on the brown side in an alkaline environment by means of a turpentine oil related ion exchanger in the presence of an oxidizing agent. goes over 'in the organic phase. In addition to PFG, resin substances, COD and AOX, soluble in organic solvents are also extracted. 508 227 In the accompanying drawings: Figure 1 shows a block diagram of the brown line with an example of integrated two-phase extraction in the pulp flow with an organic solvent alone, alternatively in combination with an organophilic complexing agent; Figure 2 shows a block diagram of the brown line with an example of differentiated extraction on the backwater system in an extractor with an organic solvent alone, alternatively in combination with an organophilic complexing agent.

According to an embodiment of the invention, the extraction can be carried out in e.g. a diffuser as shown in Fig. 1. It can then be done with or without a reducing agent as described in our previous patent applications Nos. 9603858-3 and 9603859-1, or in the presence of an oxidizing agent according to the present invention when also a delignification / bleaching of the lignocellulose can be effected, whereby a separate reactor before the diffuser can be used to e.g. be able to increase reaction time or other parameters such as temperature and pressure. The oxidizing agent may be in the process existing atmospheric oxygen, or the same may be added in some controlled manner. The organic phase with dissolved metal ion complexes / organic metal salts, together with the washing liquor, exits the diffuser to the backwater system, from which the organic phase is separated in a separator. The organic phase is extracted with dilute acid, such as sulfuric acid, whereby the metal ions are released and go into the acid phase. The organic phase (with any organophilic complexing agent) is recycled after "make up" to the diffuser and the procedure is repeated in a circular process. The acid phase is neutralized with e.g. sodium hydroxide and any remaining organic solvent in the neutralized acid phase are separated in the turpentine decantation before going to the external purification or to the chemical recovery cycle to separate the metal ions in the green liquor filtration. By vacuum distillation or water vapor distillation with or without vacuum, the organic phase (with any organophilic complexing agent) can be worked up to a higher purity when this need exists. Any organophilic complexing agent can be recovered and freed from oxygen-consuming organic substance (COD) by recrystallization of the distillation residue in an organic solvent, e.g. turpentine. Alternatively, before the distillation, the organic phase can be extracted with an alcohol-water mixture to recover the organophilic complexing agent. Preferred alcohols belong to the lower homologues, such as methanol and ethanol.

According to a further embodiment, the extraction can be done differentiated in an extractor on the backwater system, i.e. in addition to the pulp flow, as illustrated in Fig. 2, after which the backwater, after being freed from the PFG, can be recycled to the extractor.

This embodiment of the invention entails a process-technically simpler process when the organic solvent does not enter the main stream of the pulp. On the other hand, the extraction of resin solvents and PFG soluble in organic solvent becomes worse, as the organic solvent and the dissolved organophilic complexing agent, respectively, do not come into direct contact with the fiber. This process is therefore more suitable in its basic structure for removing PFG in the form of alkaline earth metals, Ca, Mg and Ba than fox fiber adsorbed Mn, which must go down to zero level in order not to be large in the bleaching process, even if most of the Mn could be extracted into the organic phase.

However, Mn on the fiber phase can still be complexed and extracted indirectly, by using water-soluble complexing agents in interaction with the organophilic complexing agents.

As can be seen from the foregoing, we found to our surprise that the organophilic complexing agents at the interface between the organic phase and the aqueous phase outcompeted the water-soluble metal ion complexes of EDTA or DTPA. Therefore, if EDTA or DTPA is added to the aqueous phase,. they are used to retrieve and transport over Mn from the fiber phase to the organic phase, after which they can be recycled without Mn back to the fiber phase and retrieve additional Mn and so on. in a circular process. The same reasoning applies to other PFGs. Without the organic phase having to come into direct contact with the fiber phase, an efficient extraction of metal ions from the fiber phase can thus be achieved, implying the advantages of the integrated system in efficiency combined with the simplicity of the differentiated system in apparatus and mode of operation.

The extraction can be carried out in the presence of an oxidizing agent for oxidation. of oxygen consumption no delignification is effected as the extractant does not come into direct contact with the pulp. It can also be made with or without a reducing agent as described in our previous patent applications Nos. 9603858-3 and 9603859-1.

The various forms of extraction according to the invention can be carried out batchwise in one or more steps or continuously countercurrently. For batch differential extraction / separation according to the gravitational principle, rose-free tanks with stirrers can be used, which are used alternately, while continuous differential countercurrent extraction. also according to the principle of gravity, consists of a tower or a column with a zone for mechanical dispersion of the liquid phases and another zone where the separation takes place. More advanced continuous apparatus for differential countercurrent extraction is based on the centrifugal principle. Suitable ones are e.g. Podbielniak, Quadronics, (Liquid Dynamics), Luwestra (Centriwestra) or De Laval extractors.

The amount of extractant, then preferably turpentine, can be selected within wide limits, the lower limit being determined by the amount of metal ions to be extracted, but also by the type of extraction equipment, and may amount to the order of five to ten times the amount of mass to be extracted in the extraction zone. integrated extraction in any washing machine, e.g. in a diffuser, while in differentiated extraction of the backwater flow in an extraction apparatus next to the pulp flow it can be laid lower, how much depends on the type of extraction apparatus.

For practical and economic reasons, the upper limit should not be set higher than is necessary for 'efficient' extraction. For example, at the levels of PFG that may be present in sulfate pulp, a laboratory scale one-step extraction resulted in a reduction in the amount of fiber adsorbed Mn, Ca and Mg according to Table 1.

By combining the metal ion extraction with a Q-step for treatment with water-soluble complexing agents, e.g. DTPA according to our patent U.S. 5,571,378 (USP Appl. Serial No 08 / 327,999) "Process for high-pH metal ion chelation in pulps" (Hampox-Q) for metal ion control on the bleaching side, with a small input of DTPA, low manganese levels for a good stabilization of the peroxide steps can If the extraction is done with anionic (cationic) ammonium bases, eg N-dodecyl-N, N, N-trimethylammonium hydroxide, dissolved in an organic solvent, the metal ion complexes of the water-soluble complexing agents can be extracted over to the At the same time, crust-forming anions such as sulphate and chloride ions are also extracted over to the organic phase.

By combining with water-soluble complexing agents according to the concepts in our previous Swedish patent applications Nos. 9603858-3 and 9603859-1, regarding "Process in the production of cellulose pulp", the anionic complexes of these can also be extracted over to the organic phase. In this way, a covering system for metal ion control can be set up and adapted to the different characteristics of existing production units.

Claims (27)

1. 508 227 39 PATENT REQUIREMENTS Liquid ion extraction agent, characterized in that it comprises one or more components with ion exchange properties selected from the group of natural and synthetic essential oils, such as turpentine oils and eucalyptus oils, and distillation, and / or hydrogenation and / or rearrangement products thereof, optionally in combination with one or more organic solvents. Extraction agent according to claim 1, characterized in that it is substantially water-insoluble or has a limited solubility in water. Extraction agent according to any one of claims 1-2, characterized in that said component with ion exchange properties is raterpentine. Extraction agent according to any one of claims 1-3, characterized in that said component with ion exchange properties is turpentine, preferably balsam, sulphate or sulphite pentine. Extractant according to one of Claims 1 to 4, characterized in that it also comprises an organophilic complexing agent. 6. Extraction solvents according to claim 5, c h n t e c h a t that the organophilic chelating agent is selected from organophilic derivatives of aminocarboxylic acids, hydroxialkylaminokarboxylsyror, hydroxy carboxylic acids, aminophosphonic acids, phosphonic acids, hydroxibensylaminokarboxylsyror, hydroxialkylbensylaminokarboxylsyror, hydroxisulfobensylaminokarboxylsyror, hydroxikarboxibensylaminokarboxylsyror or mixtures thereof. Extraction agent according to Claim 6, characterized in that the organophilic complexing agent is an organophilic derivative 508 of glycine, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (HETA) acetic acid (hydro) diethylenetriaminepentamethylenephosphonic acid (DTPMPA), monomeric or oligomeric forms of N, N-bis (2-hydroxy-5-sulfobenzyl) glycine, N, N-N, N-bis (2-hydroxy-5-carboxybenzyl) glycine or mixtures thereof. bis (2-hydroxy-5-alkylbenzyl) glycine, An extractant according to any one of claims 1 to 7, characterized in that it also comprises a hydrophilic, substantially water-soluble complexing agent. Extractant according to Claim 8, characterized in that the hydrophilic complexing agent is selected from glycine, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), monomeric or oligomeric forms of N, N-bis (2-hydroxy-5-sulfobenzyl) glycine, N, N-bis (2-hydroxy-5-alkylbenzyl) glycine, N, N-bis (2-hydroxy-5-carboxy benzyl) glycine or mixtures thereof. l0. Extraction agent according to one of Claims 1 to 9, characterized in that it also comprises organophilic cationic active compounds and / or organophilic anionic compounds. ll. because the organophilic cationic active compounds are among carboxylic acids. Extractants according to claim 10, characterized in - Selected alcohols, phenols, thiols, thiophenols, and sulfonic acids. Extraction agent according to one of Claims 10 to 11, characterized in that the organophilic anionic compounds are selected from organophilic derivatives of onium salts such as ammonium, sulfonium, oxonium and phosphonium salts, or from the corresponding homologues of amines, sulphines, oxines and phosphines, which can be converted to onium salts by proton transfer. 508 227 41 Extractant according to claim 12, characterized in that the organophilic anionic compounds are selected from N, N, N, N-tetraalkylammonium salts comprising an alkyl group having 8-22 carbon atoms and three independently selected alkyl groups having 1-2 carbon atoms. 14. A process for extracting ions from a solid or liquid phase is characterized in that the extractant according to any one of claims 1-13 is brought into contact with the solid or liquid phase. Process according to Claim 14, characterized in that it is carried out at a pH value lower than 12 in the presence of an oxidizing agent. Process according to Claim 15, characterized in that the oxidizing agent is chosen from atmospheric oxygen, oxygen, ozone, hydrogen peroxide, peroxyacids and their alkali or alkaline earth metal salts, preferably sodium, potassium, magnesium or calcium salts, and mixtures thereof. Process according to Claim 14, characterized in that it is carried out at a pH value higher than 11.5 in the presence of a reducing agent. Process according to Claim 17, characterized in that the reducing agent is chosen from hydrogen sulphide, sodium sulphide, sulfur dioxide, and alkali or alkaline earth metal salts of hydrogen sulphite, sulphite, borohydride, ditionite, tetrationite, thiosulphate, hypophosphite, orthophosphite, orthophosphates. 19. A process according to claim 18, characterized in that the reducing agent is sodium dithionite. Process according to any one of claims 14-19, characterized in that the extraction is carried out on lignocellulose, preferably in some production unit. 21. A method according to claim 20, characterized in that it is carried out in the production of semi-chemical, chemical mechanical or mechanical pulps, as well as recycled fiber pulps, for preferably bleaching oxidation with the least possible delignification. Method according to claim 21, characterized in that it is carried out directly on wood (chips), preferably in some production unit. 23. A process according to claim 20, characterized in that it is carried out in the preparation of lignocellulosic pulps by any chemical method such as the sulphate process by continuous, conventional batchwise or superbatch technique. A process according to claim 23, characterized in that the extraction is carried out in: (1) (2) (3) the cooking liquid preparation; in at least one position in at least one of the following steps or steps: the mass production process line; the chemical recycling cycle; (1) (a) chip handling before boiler, (b) pre-impregnation to boiler, (c) boiler, (d) boiler wash zone (continuous technology) or boiler displacement (superbatch technology), (e) deduction before black liquor evaporation, (f) after boilers on the brown side. on pulp and on backwater flows, (g) in the bleaching plant on pulp and on backwater flows, (h) after bleaching, e.g. in combination with paper or board machines; (2) black liquor evaporation; (3) (a) green liquor clearance, or (b) white liquor clearance. A method according to claim 20, characterized in that it is carried out in a washing apparatus in at least one of the following steps: (8) (b) boiler, (c) after boiler on the brown side, in pre-impregnation to (d) in the bleaching plant, (e) in chip handling before cooking, 508 227 43 after bleaching. 26. A method according to claim 25, characterized in that the filtrate of the washing apparatus is circulated through a separator for separating the organic phase. with the dissolved organophilic metal salts / metal complexes and oxygen-consuming organic substance (COD), that an acidic extraction is carried out on the organic phase to cleave the metal salts / metal complexes and release the metal ions, that the organic phase is recycled to the washing apparatus after loss. have first been worked up to be freed from oxygen-consuming organic matter by e.g. extraction and / or distillation and / or post-oxidation, and that the acidic aqueous phase with the liberated metal ions after neutralization can go to the recipient or to the chemical recovery cycle to separate the metal ions in the green liquor filtration. 27. A method according to claim 26, characterized in that the extraction is carried out in an extractor on the backwater system in addition to the pulp flow.