Abstract: Method for recovering chemicals and energy from sulphite thick liquor containing organic and inorganic compounds obtained when producing pulp by chemical delignification of fibrous raw material using a sulphite pulping process, the method including processing of the organic and inorganic compounds at a global temperature above 800° C. whereby producing partly at least one phase of a liquid material and partly at least one phase of a gaseous material. The processing is carried out by gasification of the sulphite thick liquor in a gasification reactor at sub-stoichiometric conditions and in the presence of an oxidizing medium. The reactor has an opening in its bottom in the form of a chute which opens directly into a quench compartment.

Abstract: A method for obtaining particulate calcium carbonate having an average particle size less than about 12 microns is provided. The method includes the steps of (1) withdrawing from a pulp mill a mixture containing calcium carbonate; (2) treating the mixture to remove contaminants contained in the mixture to produce a treated mixture containing calcium carbonate and further having a chemical composition and/or purity which substantially inhibits the fusing together of calcium carbonate particulates; (3) recovering from the treated mixture particulate calcium carbonate having an average particle size less than about 12 microns. The calcium carbonate produced has a high surface area to volume ratio and is therefore highly reactive and suitable for numerous applications such as in the treatment of soil, filler paper production, paint production, and contaminant containment in coal stack emission assemblies.

Abstract: The present invention relates to a liquid composition which comprises at least one polymer and at least one ionic liquid, the cations of which are derived from polycyclic amidine bases, and a process for isolating cellulose from cellulose-containing sources using at least one such ionic liquid.

Abstract: The invention relates to a method and apparatus for processing the black liquor of a pulp mill to recover the chemicals and energy therein. In the invention, the black liquor is pyrolyzed in a pyrolysis reactor (4), formed gaseous components are lead for utilization, sand is returned to a fluidised-bed boiler, and solid matter is mixed with water, whereby a soda-water solution is returned to the pulping process and solid carbon to the fluidised-bed boiler (1).

Abstract: A method of recovering an aqueous N-methylmorpholine-N-oxide (NMMO) solution used in production of Lyocell fiber includes: decoloring the aqueous NMMO solution by mixing the same with activated carbon using an agitation blower and by alternately energizing and de-energizing the agitation blower to contact the activated carbon with the aqueous NMMO solution thoroughly in an energy-efficient manner; filtering the aqueous NMMO solution which has been decolored through coarse filtration followed by ultrafiltration to remove the activated carbon and impurities from the aqueous NMMO solution; and concentrating the aqueous NMMO solution which has been filtered using one of a mechanical vapor recompression evaporator and a triple effect evaporator to remove water from the aqueous NMMO solution.

Abstract: A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

Abstract: A method of alkaline pretreatment of biomass, in particular, pretreating biomass with gaseous ammonia.

Abstract: The present invention relates to a process for the production of xylose and dissolving pulp from xylan-containing biomass, such as hardwood. The invention is based on prehydrolysis of the xylan-containing biomass with SO2 in specified conditions, followed by chromatographic fractionation, nanofiltration or precipitation crystallization of the xylose-containing prehydrolyzate to obtain a xylose product having a xylose content of at least 55% on DS. The dissolving pulp obtained from the process can be used for example for the production of viscose.

Abstract: An apparatus for cleaning and cooling a liquor nozzle, the nozzle including at least a liquor tube for feeding liquor and chemicals into a furnace of a recovery boiler. The apparatus includes an outer casing tube, which defines a space whereto conduits are provided for introducing water and steam to generate an emulsion or a conduit for introducing emulsion generated by the water and steam and the surface of which is provided with openings, such as pores or holes, for discharging the emulsion formed by water and steam through the outer casing.

Abstract: A method of monitoring and inhibiting scale precipitation and deposition from spent liquor in pulp mill evaporators and concentrators is disclosed. The method includes connecting a black liquor deposition monitor to a pulp mill evaporator or concentrator and measuring the thermal conductivity on the outer surface of the monitor. A controller interprets the measured thermal conductivity and determines a level of scale deposition. If the level of scale deposition is above a predetermined level, the controller is operable to introduce a scale-inhibiting composition to the spent liquor. The scale-inhibiting composition may include organic polycarboxylic acids; organic fatty acids; low molecular weight and polymeric aromatic acids; organic acid esters, anhydrides, and amides; low molecular weight and polymeric aliphatic and aromatic sulfonic acids; and low molecular weight and polymeric amines; and any combinations.

Abstract: The invention relates to a method and equipment for treatment of black liquor at a pulp mill in order to recover chemicals and energy contained therein. In the invention, the black liquor is pyrolyzed in a pyrolysis reactor (4), the formed gaseous components are forwarded for utilization and the solids are mixed with water, whereby the formed solids are returned to a lime burning kiln (1) and the sodium-hydroxide-containing liquid is returned to the pulp cooking process.

Abstract: A prebleach treatment of pulp with xylanase enzyme prior to chemical bleaching is disclosed. A process of making pulp comprises treating a pulp with xylanase in an amount of less than 50 g of xylanase per ton of pulp. The treating step is carried while buffering the pulp and xylanase with a buffering agent to a pH of from about 6.5 to about 7.5 prior to at least one bleaching stage to form a treated pulp.

Abstract: A tetradendate amide based macrocyclic ligand and its Fe(III) complex which act as activators of hydrogen peroxide. The synthetic methodology to develop the ligands is new, simple and provides better yield for each step of the ligand synthesis. The Fe(III)-complexes and hydrogen peroxide together are can perform several environmentally benign oxidation reactions. Organic dye bleaching, bleaching of pulp and paper effluent and N-oxide synthesis may be performed using the newly developed catalyst and hydrogen peroxide. Alcohol oxidation and alkene epoxidation may also be performed using the catalysts and hydrogen peroxide.

Abstract: Methods of pretreating comminuted cellulosic material with an acidic solution and then a carbonate-containing solution to produce a pretreated cellulosic material are provided. The pretreated material may then be further treated in a pulping process, for example, a soda-anthraquinone pulping process, to produce a cellulose pulp. The pretreatment solutions may be extracted from the pretreated cellulose material and selectively re-used, for example, with acid or alkali addition, for the pretreatment solutions. The resulting cellulose pulp is characterized by having reduced lignin content and increased yield compared to prior art treatment processes.

Abstract: A method of offsetting losses of ammonia from a pulping mill comprising cooking a lignocellulosic material in a cooking liquor, wherein cooking in the cooking liquor separates the lignocellulosic material into a pulp, capturing a vapor of the cooking liquor, condensing the vapor of the cooking liquor to yield a spent cooking liquor condensate, washing the pulp in a wash liquid, wherein washing the pulp removes at least a portion of the spent cooking liquor from the pulp, capturing the wash liquid, removing ammonia from the wash liquid to yield a regenerated ammonia, regenerating the cooking liquor from the spent cooking liquor condensate and the regenerated ammonia, combusting a waste material and a concentrated spent cooking liquor, wherein combusting the waste material and the concentrated spent cooking liquor yields a flue gas and heat, transferring the heat from combusting the waste material and the concentrated spent cooking liquor to water to generate steam, removing a sulfur-containing compound from th

Abstract: The invention relates to an apparatus for continuous digestion of wood chip comprising an upright generally cylindrical vessel having a top end and a bottom end. The top end of the cylindrical vessel is adapted to receive wood chips mixed with a cooking liquor to be treated therein. A first conduit is integrally attached at a first location positioned between the top and bottom ends of the vessel for selectively extracting a first quantity of cooking liquor from the vessel. The first location is positioned upstream of a second location within the vessel where the cooking liquor being at substantially full cooking temperature. A second conduit is integrally attached at a third location positioned downstream from the first and second locations of the vessel.

Abstract: Methods and apparatus for maintaining sulfur concentration in the chemical recovery cycle of a Kraft pulping process. A portion of the recovery boiler ash is dissolved, treated to remove solids, and combined with an acid to provide a solution. The recovery boiler ash may be dissolved directly in the acid. The acid may be effluent from a chlorine dioxide generator. The resulting solution is maintained in a fully dissolved state and subjected to an acid separation step to provide a sodium sulfate enriched phase, which may be used to maintain sulfur concentration in the Kraft pulping process, and a sulfuric acid phase. Chlorine ions can be separated with the sulfuric acid phase. The sulfuric acid phase can be recycled to the chlorine dioxide generator.

Abstract: The method is for the impregnation of chips during the manufacture of chemical pulp. The chips are continuously fed without preceding steam treatment to the top of an impregnation vessel that maintains atmospheric pressure. Impregnation fluid (BL) is added to the impregnation vessel and establishes a fluid level (LIQ_LEV). The chips that have been added establish a chips level (CH_LEV) that lies at least 3-5 meters over the fluid level. The temperature at the top of the vessel essentially corresponds to ambient temperature. Impregnation fluid BL is fed in to the impregnation vessel in such an amount and at such a temperature that the temperature that is established at the fluid level (LIQ_LEV) is established within the interval 90-115° C., preferably within the interval 95-105° C.

Abstract: A process for producing dissolving pulp includes a degumming step using a degumming liquor which includes hydrogen peroxide and ammonia.

Abstract: Polysulphide produced by oxidizing white liquor includes both active and inactive components. “Active” polysulphide is the only component that increases pulp yield. The amount of active polysulphide formed when manganese oxides are used as catalysts in the generating process is increased by adding a co-catalyst. Adding bismuth compounds and, in particular, bismuth oxide as a co-catalyst increases the total amount of polysulphide formed with all the manganese oxides and increases the amount of active polysulphide produced particularly when using the lower manganese oxides. The co-catalyst also increases the number of cycles in which the most active catalyst, manganese dioxide, can participate before losing efficiency. Other elements in the same group and adjacent groups in the periodic table are active but these other elements are more soluble than bismuth and are toxic.

Abstract: A method in connection with washing of pulp at a chemical pulp mill including at least an alkaline cooking process utilizing cooking liquor for producing pulp, brown stock treatment with essentially closed liquid cycles, in which the last washing device is a washing device based on pressing of pulp, a press or a washing press, a pulp bleaching plant using ECF-bleaching, wherein chloride-containing effluents are formed, a chemical recovery plant and effluent purification. The liquid flows generated at a chemical pulp mill are efficiently circulated without disturbing the main process and minimizing the emissions from the mill. Purified effluent in the amount of at least 1 m3/adt pulp is introduced into the dilution after the press or washing press, whereby the effluent is passed from the dilution into the first process stage of the bleaching.

Abstract: A method for treating liquid flows at a chemical pulp mill including at least an alkaline cooking process for producing pulp, brown stock treatment with essentially closed liquid cycles, a pulp bleaching plant using ECF-bleaching, a chemical recovery plant comprising a chemical recovery boiler, and effluent purification. Chloride-containing bleaching plant effluents are led to the effluent purification, where they are treated in order to decrease the organic matter content thereof. At least 20% of the purified effluent is returned to a pulp mill process and purified effluent is used in a last washing stage included in brown stock treatment. In the brown stock treatment the liquid flow is passed counter-currently to evaporation, wherefrom it is led for treatment to a recovery boiler process, wherein a separation process for chlorides is arranged for controlling the chloride level of the liquor cycle.

Abstract: The invention relates to a method for removing lignin from an aqueous solution. It is accomplished by adding a calcium compound and an aluminium compound to said solution. Said calcium compound is preferably calcium chloride and said aluminium compound is preferably a polymeric aluminium hydroxide salt.

Abstract: A method for treating liquid flows at a chemical pulp mill including at least an alkaline cooking process for producing pulp, treatment of brown stock generated in the cooking, a bleaching plant using ECF-bleaching, in which chloride-containing effluents are formed, an effluent purification plant for treating bleaching plant effluents and other effluents generated at the mill. At least a portion of the effluents is returned after the purification to the pulp production line as source of process water. More than one treatment line is arranged at the effluent purification plant for the mill effluents and effluents with different chemical compositions are purified in separate treatment lines so that the quality and amount of purified water from each treatment line is suitable for use in a stage or stages of the production process, whereto purified effluent is returned.

Abstract: Lignin and alkali are efficiently sorted out of alkaline black liquor discharged from the paper manufacturing/pulp and paper manufacturing industries and the treated water is made as purified water. Acid is added to the black liquor and its pH is adjusted to 2.5 to 3.5. An aggregating agent is added to have lignin contained in the black liquor settled and the black liquor is separated into lignin and clean water. Ozone gas, preferably in the micro bubble state, is given to the clean water for contact reaction.

Abstract: A method for separating carbohydrates from pulping liquors includes the steps of providing a wood pulping or wood or biomass hydrolysis pulping liquor having lignin therein, and mixing the liquor with an acid or a gas which forms an acid upon contact with water to initiate precipitation of carbohydrate to begin formation of a precipitate. During precipitation, at least one long chain carboxylated carbohydrate and at least one cationic polymer, such as a polyamine or polyimine are added, wherein the precipitate aggregates into larger precipitate structures. Carbohydrate gel precipitates are then selectively removed from the larger precipitate structures. The method process yields both a carbohydrate precipitate and a high purity lignin.

Abstract: The method and equipment are for the evaporation of hot black liquor obtained from a digestion process during the production of cellulose pulp. The black liquor is led to a multistage evaporation line with at least five evaporation stages. The black liquor that is to undergo evaporation in the evaporation line is cooled in at least one heat exchange process in a heat exchanger (HE1) against the partially evaporated black liquor that has undergone evaporation in at least one stage (I). The black liquor that is to undergo evaporation is cooled and the partially evaporated black liquor is heated by at least 5-10° C. The risk for the formation of foam and the separation of methanol are reduced. The greater part of the evaporation takes place at low temperature and at the lowest level of dry matter content in the liquor, which also suppresses encrustation in the stage.

Abstract: A process for producing fibrous material which includes the following: preparing a solution of chemicals that includes less than 25% of sulphite (calculated as Na2SO3), based on the oven-dry amount of the lignocellulosic raw material; mixing the solution of chemicals with wood in a specified liquor material; heating the solution of chemicals and the wood to a temperature above room temperature; and then either of the following alternatives: (1) removing the free-flowing solution of chemicals and digestion of the wood in the vapor phase; (2) having the wood digested in the liquid phase and separating the free-flowing solution of chemicals and the wood.

Abstract: The invention relates to a process for producing a tissue web, which is produced from a stock suspension including fibers. In this case, the volume and the tearing length are to be improved with the lowest possible freeness by the stock suspension containing lignocellolosic fibrous material made of wood or annual plants which has a tearing length of more than 6.5 km at 12°SR or a tearing length of more than 8.0 km at 15°SR and a lignin content of at least 15%, based on the oven-dry fibrous material, for coniferous wood in the unbleached state, or a tearing length of more than 4.5 km at 20°SR and a lignin content of at least 12%, based on the oven-dry fibrous material, for deciduous wood in the unbleached state, or a tearing length of more than 3.5 km at 20°SR and a lignin content of at least 10%, based on the oven-dry fibrous material, for annual plants in the unbleached state.

Abstract: Method and apparatus for batch displacement digester systems to increase tank farm vessel temperatures for more efficient delignification rates by mitigating the formation of flow channels in the chip bed, minimizing the vertical temperature gradient in the digester and segregation of returning liquors to the tank farm from the digester.

Abstract: Method and apparatus for reducing the amount of sludges produced in a pulp and/or paper mill. The sludge produced in a pulp and/or paper mill as a result of waste water treatment is conveyed to solid fuel and the produced fuel-sludge mixture is burned in a power boiler. The solid fuel is heated before sludge is mixed therein.

Abstract: A process and method for recycling cigarette butts is disclosed. The process and method involves reacting ground cigarette butts with a solvent and mineral spirits and then shaping and drying the resultant product. Once the processed cigarette butts have hardened or cured the material may be formed into useful objects with no leaching of chemicals upon contact with water.

Abstract: In the process for producing kraft pulp, performing a potassium ion removal step of flowing an aqueous solution containing ashes recovered from a combustion exhaust gas generated in a black solution combustion step by a dust collector through a packed bed filled with a sodium-type cation exchange organic resin to adsorb and remove potassium ions contained in the aqueous solution; and a regeneration step of treating the cation exchange organic resin used in the potassium ion removal step with a solution consisting essentially of aqueous sodium hydroxide to regenerate the cation exchange resin, where a fraction recovered from the potassium ion removal step which is rich in sodium sulfate and sodium carbonate is recycled to the black solution concentrating step, and a sodium hydroxide effluent recovered from the regeneration step is recycled to a bleaching step and used in a bleaching process.

Abstract: A method for impregnating chips in a continuous digestion system with an impregnation vessel and a digester. The digestion system has a heat exchanger arranged between a first return line and a black liquor line. The heat exchanger allows a transfer of heat between the two lines. A principal part of the fluid contents of the impregnation vessel is constituted by chips moisture, steam condensate, added white liquor, and the fluid withdrawn from the top separator at the first return line, whereby the impregnation fluid in the impregnation vessel does not contain any substantial amount of black liquor from the digester. An impregnation vessel is established that is hydraulically isolated, in which the flow of fluid and the establishment of its alkali content take place without any influence from the fluid flow in the digester process.

Abstract: A procedure for the continuous cooking of chemical pulp, comprising an impregnation vessel 101 and a digester 102. The chips are impregnated in the impregnation vessel 101and are fed after impregnation together with circulation fluid through a transfer line 103 to a top separator 105 on the digester 102 in order to be cooked. A fraction of the circulation fluid is withdrawn at a top separator 105 and returned to the bottom of the impregnation vessel 101 via a return line 106. Black liquor is withdrawn from the digester via a black liquor line 108 to the impregnation vessel 101. The invention is characterized in that a heat exchanger 107is arranged between the return line 106 and the black liquor line 108. The heat exchanger 107 allows the exchange of heat between the two lines, but does not allow the exchange of fluid. The temperature of the black liquor in the black liquor line 108 after passing through the heat exchanger 107 has been cooled by 10-15 ° C.

Abstract: Polysulphide produced by oxidizing white liquor includes both active and inactive components. “Active” polysulphide is the only component that increases pulp yield. The amount of active polysulphide formed when manganese oxides are used as catalysts in the generating process is increased by adding a co-catalyst. Adding bismuth compounds and, in particular, bismuth oxide as a co-catalyst increases the total amount of polysulphide formed with all the manganese oxides and increases the amount of active polysulphide produced particularly when using the lower manganese oxides. The co-catalyst also increases the number of cycles in which the most active catalyst, manganese dioxide, can participate before losing efficiency. Other elements in the same group and adjacent groups in the periodic table are active but these other elements are more soluble than bismuth and are toxic.

Abstract: An inventive method of papermaking can be provided for creating an optimum wet end environment. In a preferred method, an aqueous solution of sodium hypochlorite acidified by hydrochloric acid to have a pH of greater than or equal to 4 and less than 7 and adjusted to have an effective chlorine concentration of 1,000 to 10,000 ppm, preferably 3,000 to 8,000 ppm is prepared and charged to a white water pit in a manner to be effective chlorine concentration therein to greater than or equal to 0.5 ppm. Before a step of papermaking, it is preferred that aqueous solution sodium hypochlorite having pH of greater than or equal to 4 and less than 7 is added continuously or intermittently to a raw material water with the expectation that at breaching a residual chlorine concentration becomes greater than or equal to 500 ppm.

Abstract: The invention features methods and systems for calcining wet calcium carbonate lime mud produced in a re-causticizing manufacturing operation, for instance, Kraft pulp mill lime mud (“lime mud”) and converting it to re-burned lime by (a) feeding wet lime mud obtained from a re-causticizing manufacturing process into a flash dryer and then feeding the dried lime mud into a bubbling fluid bed calciner thermally linked by moving media heat transfer (MMHT) utilizing solid particulate media to a circulating fluid bed combustor wherein the MMHT provides heat input for calcination and drying; (b) recycling the media being from said calciner to said combustor wherein said combustor receives mill WWTP sludge, or precipitated lignins, or biomass, or NCGs as fuels to re-heat the solid particulate media; and (c) recovering calcined “soft-burned” lime mud from the fluid bed calciner.

Abstract: The present invention refers to a method to recover chemicals in mechanical pulping by evaporating mechanical pulping or recycled fibre plant effluent and burning the received concentrate under oxidative atmosphere to yield sodium carbonate. According to the invention said sodium carbonate is dissolved into water together with CaO in order to convert said sodium carbonate into sodium hydroxide at least partly.

Abstract: A continuous and batch system to produce cellulose, native lignin and unicellular protein from any form of vegetation in a closed process. The biomass is mixed in the impregnate solution of nitric acid and/or ammonium hydroxide and water. After a period of time at room temperature and atmospheric pressure the chemical solution is recycled. The biomass is moved to the reactor and heated. Evaporated impregnate is recovered via absorption tower and recycled back to chemical solution. The biomass is moved to an alkaline solution, then cooled to separate pulp from black liquor. The black liquor is pumped to a separation tank and is treated to precipitate lignin. The solution is filtered to separate sweet liquor and lignin. The lignin is dried and the sweet liquor is fermented to produce unicellular protein.

Abstract: A method for the preparation of pulp by means of alkaline cooking, in which method spent liquor is transferred to pressurized tanks, and at least one liquor is expanded corresponding to a temperature difference of 1 to 5° C. The generated steam is led to turpentine recovery. Thus, the removal of turpentine and gases dissolved in said liquor is effective, the amount of recovered turpentine increases, and pulp of better washability and higher quality is obtained.

Abstract: The method is for bleaching cellulose pulp in a bleach line that has at least two bleaching steps. The filtrate distribution is led up through the bleaching line counter-currently to the flow of cellulose pulp established in the bleaching line. A single joint main conduit is used for the bleaching steps. Wash filtrates obtained from the wash steps, used after or before the bleaching step, are led in conduits to branch locations on the main conduit that are positioned downstream of the branch location for drawing off of wash and/or dilution liquor for the wash step in question. All branch points in the joint main conduit are in fluid communication with one another along the main conduit.

Abstract: Oxidized white liquor is heat treated to increase the concentration of polysulphide measured at 285 or 286 nm (PSUV) or measured at 416 nm (PSVIS) and the PSUV/PSGR or PSVIS/PSGR ratio, whereby the content of active polysulphide in the total polysulphide is increased which active polysulphide can be exploited to increase pulp yield in Kraft pulping.

Abstract: A method of treating solid containing material derived from effluent or sludge from a plant for deinking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: Compositions and method of improving inhibition of calcium salt scale formation under the conditions found in chemical pulp processes in which an effective amount of selected phosphonates or phosphonate blends is admixed with the black liquor composition recovered from the digester in a chemical pulping process. The compositions and method are especially well suited for use in the Kraft pulping process.

Abstract: A process (44) for the production of pulp and paper (28), recycling of cooking chemicals (3, 29), combustion of biomass (30, 37) and generation of heat and electric energy (27, 40) comprising a pulp and paper mill (28), in that the part of the process which is recycling cooking chemicals is adjusted from combustion (29) to gasification (3) to generate synthesis gas (14); and that biomass is added (33, 39) in an amount sufficient for compensating of the decrease in heat and electricity generation as a consequence of the generation of synthesis gas (14).

Abstract: The improved process is achieved by introducing depuration of green liquor and lime before causticization and two special causticization steps in causticization procedure of conventional chemical recovery processes. It not only avoids the generation of waste residue (lime mud) from the beginning and saves the re-burning and filling land of lime mud, but also can directly produce a series of precipitated calcium carbonate products with various particle sizes by regulating process conditions while alkali is recovered. The CaCO3 products include CaCO3 wherein ?50% of CaCO3 has a particle size below 2 ?m, CaCO3 wherein ?90% of CaCO3 have a particle size below 2 ?m, and a superfine CaCO3 having an average particle size <1 ?m. The CaCO3 obtained by this process can be directly used for papermaking and other industrial applications.

Abstract: The method is for the manufacture of cooked cellulose pulp in which the starting material, preferably chips, undergoes a successive increase in temperature towards cooking temperature. This is done while the chips are first treated in a pre-treatment zone in which the main part, greater than 50%, of fresh white liquor necessary for the cooking stage is added, after which this alkali-rich treatment fluid is withdrawn and replaced to a major extent by black liquor. The alkali-rich treatment fluid that has been withdrawn after the pre-treatment stage is then added to the cooking stage, which is why the addition of fresh white liquor to the cooking stage is reduced to an equivalent amount. Maximal yield-enhancing effect is obtained using poly-sulphide-rich white liquor during the pre-treatment at a temperature in the interval 60±40° C. and retention time in the interval 2-60 minutes, preferably 2-10 minutes.

Abstract: The method is for production of green liquor in association with a causticizing process during recovery of chemicals in manufacture of sulphate pulp. A smelt (14) of chemicals principally consisting of Na2S and Na2CO3 from a soda boiler (1) is provided. Weak liquor (15) that contains dissolved NaOH and CaO is provided. A dissolving tank (2) is provided in which the smelt (14) from the soda boiler (1) is dissolved in the weak liquor (15) it order to form green liquor (16). A solution of NaOH is added to the weak liquor (15), at a position before the weak liquor (15) is added to the dissolving tank, in order to increase the concentration of NaOH in the weak liquor (15) such that a fraction of CaO that is presently dissolved in the weak liquor (15) precipitates.

Abstract: Compositions and method for improving properties of pulp produced or reducing the digester cycle time in alkaline chemical pulping processes in which an effective amount of at least one selected phosphonate or carboxylate compound or mixtures thereof is admixed with the alkaline aqueous mixture in the digester of the chemical pulping process. The compositions and method are especially well suited for use in the Kraft pulping process.