Abstract: Aqueous black liquor is gasified in a molten salt by spraying the black liquor into an enclosed zone above the surface of a turbulent molten salt pool. The black liquor is dried by means of hot gases rising from the surface of the pool and the resulting solid particles falling into the turbulent molten salt pool are dispersed and converted into a combustible gas and a reduced melt in which sulfide comprises at least about 95% of the total sulfur present. In a preferred embodiment the product gas is purified, burned and utilized in a gas turbine.

Abstract: The disclosure relates to a process for the removal of solid CaS from a gas stream in which the CaS has been formed and then the conversion of that solid CaS by reaction with an aqueous NaOH solution to produce solid Ca(OH).sub.2 and a liquor stream containing dissolved NaHS. This removal and conversion process is described as being used in conjunction with a process for gasifying black liquor from a kraft pulping process in which H.sub.2 S is scrubbed from the gases using calcium compounds to form the CaS.

Abstract: A method for reprocessing an ozone-containing gas present in a pulp bleaching plant comprising the steps of supplying the ozone-containing gas to a scrubber and reducing the ozone concentration of the gas as the gas flows through the scrubber. The step of reducing comprises the steps of supplying an alkaline medium to the scrubber and flowing the ozone-containing gas in countercurrent relationship with the alkaline medium within the scrubber so as to provide intimate contact between the ozone-containing gas and the alkaline medium, thereby converting the ozone-containing gas into a substantially ozone-free gas. The alkaline medium may comprise one of the following: a sodium hydroxide solution; white liquor; post oxygen stage filtrate; weak black liquor; or filtrate from an Eo stage of the pulp bleaching plant. The method further comprises the step of separately discharging the ozone-containing gas and the alkaline medium from the scrubber.

Abstract: Resonant tubes of a pulse combustor are immersed in a bed of solid particles in a reaction zone to provide indirect heat from the pulsating combustion gases to the solid particles of the bed. The bed is maintained in an agitated state by a gas or vapor flowing through the bed. Reactant materials are introduced into the agitated bed and undergo reaction at enhanced rates resulting from heat transfer coefficients at least about twice as high as those of steady flow combustors and an intense acoustic pressure level propagated from the pulsating combustor into the reaction zone. The apparatus is useful, for example, to steam reform heavy hydrocarbons and to gasify carbonaceous material, including biomass and black liquor to produce combustible gas at relatively low temperatures, with steam being utilized as the bed fluidizing medium. Black liquor gasification, utilizing sodium carbonate as bed solids, results in liquor energy and chemical content recovery without smelt production.

Abstract: When producing green liquor for later manufacture of cooking liquor, it is endeavoured that the green liquor shall be readily clarified and/or readily filtered. This endeavour is achieved with the present invention, which relates to a method of producing green liquor in which waste liquor separated from cellulose pulp and derived from a cooking stage and possibly from one or more bleaching stages is worked up including known treatment stages such as evaporation, combustion, smelt dissolving and other green liquor preparation, and in which a calcium containing chemical is added to the waste liquor prior to combustion, or is added at the combustion of the waste liquor. The method is characterized in that carbon deriving from the smelt is caused to equal at most 0.

Abstract: The process for producing hydrogen peroxide, used in the bleaching of pulp, uses the hydrogen generated wholly or partly by the gasification or partial combustion of cellulose spent liquors used in digesting cellulose material to produce the hydrogen peroxide.

Abstract: A method for recovering sodium from a spent cooking liquor used in a kraft pulping process employing sodium hydroxide as a cooking agent resulting in the presence of sodium and sulfur combined with various elements in the spent cooking liquor. Black liquor is converted to green liquor, and the green liquor is reacted with lime in a causticizer to produce caustic and calcium carbonate. The caustic is recovered for use as a cooking liquor and the calcium carbonate is heated in a lime kiln to provide a source of lime. Flue gases containing free lime evolved from the lime kiln are contacted with a sodium carbonate solution in a scrubber to convert lime to caustic.

Abstract: A method for the recovery of chemical values from spent lignocellulosic pulping liquor salts to produce white liquor of different sulfidities. Preferably, the white liquor is in the form of separate liquid streams, each of which is of a sulfidity that is different from the sulfidity of others of the streams. The method also provides for developing a white liquor stream which is essentially free of sulfide values, but which contains sodium hydroxide. Further, the method provides for recovery of titanium values for recycling.

Abstract: A method for adjusting the sulphur/sodium ratio in a soda recovery boiler when strong sulphurous odour gases are burned therein. According to the method, sodium is introduced into the soda recovery boiler in an amount proportional to the amount of sulphur either as sodium hydroxide, sodium carbonate compounds or soap, whereby the sodium and sulphur react, forming sodium sulphate, which can be removed from the flue gases together with fly ash.

Abstract: The specification describes a process for recovering alkali metal hydroxides from an organic liquor such as black liquors derived from pulping wood chips. The organic liquor is burned in a fluidised bed combustion furnace containing fluidised particles of an iron rich mixed oxide of an alkali metal and iron. Particles of alkali metal ferrite are extracted from the furnace and dissolved in a solution of alkali metal hydroxide to form a more concentrated solution of alkali metal hydroxide and a precipitate of the iron rich mixed oxides of alkali metal and iron. A mixed oxide disclosed in the specification generally has the following formula: NaFe.sub.5 O.sub.8.4H.sub.2 O.

Abstract: A high solids black liquor which has solids content of at least 65% by weight of liquor is mixed with a viscosity reducing additive prior to firing in a chemical recovery furnace. The additive is an admixed compound consisting of monoethylene glycol, diethylene glycol and triethylene glycol.

Abstract: The sulphur content and/or the sulphur compound composition of a melt in a recovery boiler of a pulp mill is adjusted by bringing a gas into contact with the melt. The gas may be a gaseous sulphur compound or a reducing gas. Bringing the gas into contact with the melt increases the sodium sulphide content of the melt while decreasing the sodium carbonate content, so that the sulphidity of the melt increases. The sulphur-containing gas may be produced by pressure heat treatment of black liquor, so that the black liquor burned in the recovery boiler has a lower sulphur content and thereby reduces the boiler sulphur emissions, and boiler corrosion problems.

Abstract: In a chemicals recovery plant in a sulphate pulp mill, in order to provide green liquor with improved sedimentation and filtration properties, there is passed, from a flow (10) of slaked lime and green liquor between a lime slaker (9) and a causticizing tank (1 1), a partial flow (32, 35) to a soda dissolver (2) or to a container (26) for unclarified green liquor provided after the soda dissolver. For this purpose there is provided, in a line (10) between the lime slaker (9) and the causticizing tank (11), a branch line (32, 35) which passes to the soda dissolver (2) or to a container (26) for unclarified green liquor provided after the soda dissolver.

Abstract: In general, the invention features method for regulating sulfur dioxide emissions from the recovery furnace of a Kraft paper mill.

Abstract: The invention relates to a process for preparation, under reducing conditions, of cooking liquors having high sulphidity for sulphate pulp cooking, wherein the black liquor obtained in the cooking process is fed, after evaporation, completely or partly to a reactor operating at increased temperature which is obtained by energy supply from an external heat source and/or release of energy from the black liquor, a melt essentially consisting of sodium sulphide being formed and withdrawn to be further processed to cooking liquor. The process of the invention is characterized in that in addition there are fed to the reactor the whole or part of sulphur-containing and/or sulphur- and sodium-containing materials present in the pulp mill, including sulphur-containing and/or sodium- and sulphur-containing make-up chemicals used for the total chemicals balance of the pulp mill, in such a way that the mole ratio of sodium to sulphur in the total mixture fed to the reactor is within the range of 1.5 to 4.

Abstract: A method for white liquor oxidation in a kraft mill utilizes a two-stage selective oxidation system in which the first stage is operated to remove sulfide while the second stage is operated to oxidize a significant fraction of the remaining oxidizable sulfur compounds to sulfate. The resulting selectively oxidized white liquor products are used as alkali sources for various process steps in the mill. Optionally, white liquor can be oxidized in a single stage to convert a significant fraction of the oxidizable sulfur compounds to sulfate. Methods for controlling the selective oxidation process are disclosed.

Abstract: A simple process for preparing acicular calcium sulphate dihydrate is provided in which a slurry of calcium carbonate containing 100 to 800 grams per liter calcium carbonate is mixed with a solution of sulphuric acid containing 80 to 500 grams per liter sulphuric acid in proportions which produce a calcium sulphate slurry having a pH from 0.5 to 1.5. The process can be used to neutralise by-product sulphuric acid from the preparation of titanium dioxide with crushed limestone. Preferably the calcium sulphate slurry is stirred after formation to reduce the level of unreacted carbonate. The calcium sulphate produced has an aspect ratio of at least 4:1 and has excellent properties for use in paper. The process enables the production of acicular calcium sulphate without employing special crystallisation procedures.

Abstract: The grit conveyance system of a classifier having a wash region above the liquid layer is provided with a vacuum means in the wash region for positive removal of liquids through a metal screen for disposal.

Abstract: A process is provided for the manufacture of ferric sulphate compounds from ferrous sulphate in a closed vessel containing a liquid phase and a vapor phase, the process comprising the oxidation of Fe.sup.++ to Fe.sup.+++ under pressure utilizing commercial oxygen in the closed vessel using NOx as a catalyst where x is a number between 1 and 2 inclusive of 1 and 2 and wherein the process comprises the following reactions: ##EQU1## wherein n is any integer greater than or equal to two (2) and y is any integer which is equal to, or greater than zero (0) and less than 3n and wherein the oxidation of Fe.sup.++ is affected by spraying the liquid phase including a solution containing Fe.sup.++ introduced to the closed vessel, through a reacting cloud comprising NO, NO.sub.2 and O.sub.2 enclosed in the vapor space of the closed vessel and wherein substantially only Ferric ions is present in the liquid phase in the closed vessel relative to the amounts of Ferric and Ferrous ions prior to the addition of FeSO.sub.4.

Abstract: Paper pulp (e.g. kraft pulp) is produced utilizing at least two different supplies of cooking liquor, one having low sulfide content, and the other high sulfide content. The high sulfide content supply is typically used to impregnate the pulp or otherwise treat it first, while the second supply is used in other cooking stages (e.g. a digester), whether co-current or countercurrent. The different sulfur content liquors are obtained by heat treating (under pressure) black liquor to drive off sulfur compounds, and absorbing them into white liquor to produce a high sulfide stream. The low sulfide stream is made by conventional treatment of the black liquor after heat treating and evaporation. Utilizing multiple sulfide content supplies results in an optimum viscosity/kappa ratio and/or pulp strength properties for the pulp produced.

Abstract: Off gases from black liquor heat treatment, evaporators, wood pulp digesters, etc. are treated to produce primarily hydrogen sulfide and sulfur free fuel gases such as methane, carbon monoxide, hydrogen, and ethylene. Then the hydrogen sulfide is used to produce sodium polysulfide in white liquor for cooking wood chips to produce pulp by the kraft process. Polysulfide may be formed in three different ways: by supplying air to a fuel cell into which white liquor and the hydrogen sulfide containing gas have been introduced; by bringing clarified white liquor and hydrogen sulfide containing gas into contact with a wet-proofed activated carbon catalyst and oxygen containing gas; or by bringing unclarified white liquor into contact with the gas and oxygen containing gas, with lime mud acting as a catalyst, and then clarifying the polysulfide-rich white liquor produced to remove the lime mud. The white liquor produced contains about 0.5-8% on wood sodium polysulfide.

Abstract: The present invention relates to a process for the separation of sulphur and sodium compounds from a hot process gas generated during gasification of spent liquor from the kraft pulping industry, through contact with hydrogen sulphide ion and hydroxide ion containing alkaline liquids in two or more stages, whereby the process gas in a first stage passes through a venturi throat and/or liquid trap where it is brought into contact with an alkaline washing liquid, whereby melt droplets in the process gas are separated from the gas flow and drawn off as an aqueous solution, whereby the process gas in a subsequent washing stage is brought into contact with a finely dispersed washing liquid containing hydroxide ions and hydrogen sulphide ions with a molar ratio greater than 4:1.

Abstract: Nozzles for directing a jet of steam against a spout flow stream of sodium recovery boiler smelt are secured to an articulating anchor mount for the purpose of maximizing the shattering impact of the steam jet upon the smelt flow stream under a wide range of boiler operating conditions.

Abstract: A process for the manufacture of ferric sulphate from ferrous sulphate in a closed circuit or vessel comprising a liquid phase and a vapor phase, the process comprising the oxidation between about 70.degree. C. to about 150.degree. C. of Fe.sup.++ .fwdarw.Fe.sup.+++ under pressure utilizing oxygen in the closed circuit or vessel using (NO.sub.x) as a catalyst where x is a number between 1 and 2 inclusive of 1 and 2, {NO.sub.x being a mixture of NO and NO.sub.2 } and wherein the process comprises the following reactions:1) NO+1/2O .sub.2 .fwdarw.NO.sub.2, and2) 2FeSO.sub.4 +H.sub.2 SO.sub.4 +NO.sub.2 .fwdarw.Fe.sub.2 (SO.sub.4).sub.3 +H.sub.2 O+NO, and wherein the oxidation of Fe.sup.++ is affected by spraying the reacting solution (taken for example from the bottom of the vessel or closed circuit containing the reacting solution) through a reacting cloud in the vapor phase comprising NO, NO.sub.2 and O.sub.2 enclosed in the vapor space of the closed circuit of vessel.

Abstract: A process for the manufacture of ferric sulphate from ferrous sulphate in a closed circuit or vessel comprising a liquid phase and a vapor phase, wherein the vapor phase is essentially a closed system, the process comprising the oxidation between about 70.degree. C. to about 150.degree. C. of Fe.sup.++ .fwdarw.Fe.sup.+++ under pressure utilizing commercial oxygen in the closed circuit or vessel using (NO.sub.x) as a catalyst where x is a number between 1 and 2 inclusive of 1 and 2, and wherein the process comprises the following reactions:1) NO+1/2O.sub.2 .fwdarw.NO.sub.2, and2) 2FeSO.sub.4 +H.sub.2 SO.sub.4 +NO.sub.2 .fwdarw.Fe.sub.2 (SO.sub.4).sub.3 +H.sub.2 O+NO,and wherein the oxidation of Fe.sup.++ is affected by spraying the reacting solution containing Fe.sup.++ introduced to the closed circuit or vessel through a reacting cloud in the vapor phase comprising NO, NO.sub.2 and O.sub.2 enclosed in the vapor phase of the closed circuit or vessel and wherein substantially only Fe.sub.2 (SO.sub.4).sub.

Abstract: A one-step slaking/causticizing method for producing white liquor from unslaked lime and clarified green liquor comprising introducing a feed slurry of unslaked lime and clarified green liquor into a pressurized slaker/causticizer reaction zone and maintaining the mixture in the zone at a temperature, under sufficient pressure and for a time sufficient, in one step to slake the lime and to convert the slaked lime to a white liquor containing product slurry.

Abstract: A method of cleaning green liquor of solid particulate impurities by adding caustic lime corresponding to 0.5 to 10% of the amount of caustic lime needed for complete causticizing of the green liquor to the green liquor in a soda dissolving tank or in a separate mixing tank to which the liquor is led directly from the dissolving tank. Calcium carbonate precipitates and forms, with the impurities, particles having better settling and filtration properties than particles in green liquor which has not been treated with caustic lime.

Abstract: A method and apparatus are disclosed for concentrating an alkaline waste liquor containing sulfur compounds, the so-called black liquor, which is discharged from a step of Kraft-cooking wood fibers, in order to recover the cooking chemicals from said waste liquor, characterized in that CO.sub.2 gas and/or a gas containing CO.sub.2 gas is added to said waste liquor as a boiling-point-lowering agent, viscosity-lowering agent and solidification promoter, after a step of oxidizing said waste liquor and in or prior to one or more stages during the step of concentrating said waste liquor. Also disclosed is an apparatus for concentrating an alkaline waste liquor containing substantially no sulfur compounds (i.e.

Abstract: Process for causticizing a water solution containing alkali carbonate with calcium oxide and hydroxide by bringing the water solution containing alkali carbonate into contact with the calcium oxide or hydroxide and by separating the alkali hydroxide solution arisen in the causticizing from the calcium carbonate precipitate. The water solution containing alkali carbonate is conducted through a bed which has been formed by mixing calcium oxide and calcium carbonate in the causticized alkali solution and by removing the excess alkali solution.

Abstract: Method and apparatus for controlling the reactivity of lime produced in a lime cycle process that includes the steps of forming burnt lime in a kiln, washing and filtering of lime sludge, and causticizing of green liquor, which lime cycle process steps are carried out under variable operating conditions. At least one mechanical property of the burnt lime is measured, and at least one operating condition of the time cycle process is adjusted, based on the measured mechanical property of the burnt lime, so as to thereby control the reactivity of lime produced in the lime cycle process.

Abstract: A process for combusting black liquor by enriching the normal process air used in the combustion process by the addition of up to 5% oxygen.

Abstract: The invention relates to a process of increasing the solids content of black liquor at its recovery in a sulfate pulping process. According to the invention, the liquor is first heated at a pressure which is so high that no boiling occurs at the heating temperature, after which the liquor is led to a tank where its pressure is released to a value below the saturation pressure of steam at the relative temperature of the liquor such that water is evaporated. The liquor thus concentrated can be led to the liquor combustion in the recovery process.

Abstract: Process for recovering chemicals and energy from cellulose waste liquors preferably black kraft liquor obtained in a paper pulp sulphate process, comprising the following, three distinct and separate steps: In the first step the concentrated black liquor is gasified in a pressurized gasification reactor by so called flash-pyrolysis at 700.degree. to 1300.degree. C., normally 800.degree.-900.degree. C., whereby an energy rich gas is produced, and in which the inorganic chemicals of the black liquor are contained in the form of molten suspended droplets, mainly comprising sodium carbonate and sodium sulphide. In the second step the gas from the gasification reactor is rapidly cooled through direct contact with water, and with green liquor, which is formed when the molten droplets and the hydrogen sulphide are dissolved in the quench liquid. The cooled gas subsequently passes through a scrubber.

Abstract: A process for cooking and bleaching pulp in a closed system, wherein spent liquors from the cooking and the bleaching are recovered and their chemicals are regenerated and recycled as cooking and bleaching chemicals.

Abstract: A process for recovering the energy and chemical content of an aqueous black liquor utilizing a reactor containing a drying zone located above a gasification zone. The reactor contains a bed of porous solid carbonaceous material in the gasification zone. Heat losses are restricted, preferably from both zones, by the provision of a layer of insulating material about the reactor. An oxygen-containing gas is introduced into the gasification zone in an amount less than about 60% of that required for complete combustion of the black liquor such that there is produced partial combustion and gasification reactions sufficient to maintain the temperature at an upper surface of the bed in the range of from about 870.degree. to 1200.degree. C. and to form a hot combustible gas which rises from the gasification zone.

Abstract: A method for increasing the efficiency of the caustizing process which comprises: (a) adding to a green liquor between 78 and 82% of the stoichiometric amount of lime necessary to react with the amount of Na.sub.2 CO.sub.3 present in the green liquor to obtain a white liquor containing NaOH and lime mud. The white liquor is then clarified by extracting the lime mud present to obtain a white liquor having a total solid concentration of about 10-60 grams/liter. The supernatant liquid of the white liquor is treated with an additional amount of lime to increase the causticity to about 87%, then allowing further causticizing reaction between the lime and Na.sub.2 CO.sub.3. The remaining lime mud present is removed to obtain a white liquor which has the causticity of about 87%. One is thus able to raise the causticity of partially clarified white liquor following the normal causticizing process, the mud present being sufficient to increase causticity without substantially decreasing settling rate.

Abstract: The invention concerns a causticizing procedure by which from soda liquor derived from a sulphate cellulose digesting process and from unslaked lime is produced white liquor for reuse in the digesting process, over lime slaking and a subsequent causticizing reaction proper. It is essential in the invention that the lime slaking is carried out using white liquor, whereafter the causticizing reaction proper is allowed to take place between the slaked lime and soda liquor combined therewith. The requisite white liquor is obtained by recirculating part of the white liquor produced by the causticizing process, to the slaking step, where it either completely or partially replaces the soda liquor employed in prior art. By using white liquor, one avoids the foaming, interfering with the process, which is encountered in the slaking step.

Abstract: An improvement in a chemical recovery process in which a hot liquid smelt is introduced into a dissolving tank containing a pool of green liquor. The improvement comprises preventing smelt explosions in the dissolving tank by maintaining a first selected superatmospheric pressure in the tank during normal operation of the furnace; sensing the pressure in the tank; and further impinging a high velocity stream of steam upon the stream of smelt whenever the pressure in the tank decreases below a second selected superatmospheric pressure which is lower than said first pressure.

Abstract: A method of recovering alkaline chemicals from a material containing sodium or potassium compounds. The material is gasified by an external heat source after which the gas is rapidly cooled by arranging it to contact with cooled solid particles separated from the gas.

Abstract: Described herein is a process for producing potassium salts from potassium-based liquors for pulping of lignocellulosic material. The process comprises the steps of(a) digesting lignocellulosic material with a potassium-base aqueous cooling liquor to obtain an aqueous slurry of partially delignified pulp of the lignocellulosic material;(b) separating the pulp from the spent potassium-base aqueous cooling liquor;(c) concentrating the spent pulping liquor; and(d) recovering potassium salts including potassium carbonate, potassium sulphate and potassium lignosulphonate from the concentrated spent pulping liquor. The recovered potassium salts find numerous uses, an example being use in fertilizers.

Abstract: A process is provided for producing nitrogen oxides from aqueous waste cellulose pulp liquors containing nitrogen compounds including oxygen linked to nitrogen in the molecule, which includes initiating an autocatalytic reaction generating nitrogen oxide in a liquid phase comprising aqueous waste cellulose pulp liquor containing nitrogen compounds including oxygen linked to nitrogen in the molecule at a temperature within the range from about 40.degree. to about 180.degree. C. and at an acid pH within the range from about 0 to about 5 in the presence of nitrate ion NO.sub.3.sup.- in a concentration calculated as nitrogen within the range from about 0.2 to about 5 grams moles per kilogram of water and of lignin in a weight ratio lignin:water within the range from about 0.001:1 to about 1:1; and then continuing the autocatalytic reaction while maintaining a gas phase in contact with the liquid phase having a partial pressure of nitrogen oxide within the range from about 0.

Abstract: A partially-oxidized spent pulping liquor is produced which is added to unoxidized strong spent pulping liquor prior, during, or subsequent to concentration to form a novel partially-oxidized, concentrated, high total solids spent pulping liquor. This novel, partially-oxidized, concentrated spent liquor is capable of being combusted in a spent liquor recovery furnace without the addition of auxiliary heating fuel with a resultant increase in the effective capacity of that furnace.

Abstract: The present invention relates to a method and means of increasing capacity and improving the chemical recovery process when using a conventional soda recovery boiler for recovering chemicals out of spent sulphate liquors. The spent sulphate liquor is supplied in full or in part to a liquor gasifier (8) while external energy independent of combustion is simultaneously supplied (at 16, 17). The temperature and oxygen potential are carefully controlled independently of each other by means of controlled supply of the energy. The product thus obtained is thereafter introduced in full or in part into a soda recovery boiler (1).

Abstract: The invention relates to the recovery of chemicals from waste liquor from wood pulp process, primarily black liquor, while utilizing energy liberated. Controlled total vaporization of the pulp waste liquor at high temperature and low oxygen potential is achieved by the external supply of energy. During the subsequent condensation and separation of melt or water solution is obtained which, without causticizing, can be used for the preparation of white liquor, and also an energy rich gas and mainly free from sulphur, consisting primarily of carbon monoxide and hydrogen.

Abstract: A concentrated aqueous black liquor containing carbonaceous material and alkali metal sulfur compounds is treated in a gasifier vessel containing a relatively shallow molten salt pool at its bottom to form a combustible gas and a sulfide-rich melt. The gasifier vessel, which is preferably pressurized, has a black liquor drying zone at its upper part, a black liquor solids gasification zone located below the drying zone, and a molten salt sulfur reduction zone which comprises the molten salt pool. A first portion of an oxygen-containing gas is introduced into the gas space in the gasification zone immediatley above the molten salt pool. The remainder of the oxygen-containing gas is introduced into the molten salt pool in an amount sufficient to cause gasification of carbonaceous material entering the pool from the gasification zone but not sufficient to create oxidizing conditions in the pool.

Abstract: A readily adjustable shatter jet mechanism comprises a frame which rotatably and displaceably receives a fluid supply pipe assembly. The assembly includes a fluid supply pipe which is pivotally movable. A nozzle is connected to the pipe and can be rotated into one of a plurality of rotational positions. The assembly can be disengaged from the frame and reengaged with the frame at a different location so that the pipe and its nozzle can also be displaced with respect to the frame. In this way the fluid jet can be directed in a variety of directions toward a smelt stream to be broken up by the fluid jet.

Abstract: This invention is a process for recovering sodium hydroxide directly from black liquor. The process involves pyrolyzing the black liquor in the absence of oxygen to produce a product containing sodium carbide, and hydrolyzing the sodium carbide to form sodium hydroxide. The pyrolysis is carried out at about 4000.degree. F. using radiant energy.

Abstract: The present invention seeks to provide a method in which the soda lye obtained as a result of cellulose cooking process and unslaked lime are used for producing white liquor which can be re-used in the cooking process. In this method, the heat released by the slaking of lime with soda lye is recovered by a high pressure slaking process wherein the heat is transferred, either to the steam separating from the lye, which steam is then led to the desired application, or to some other medium to be heated. The present invention is characterized in that the soda lye to be causticized is divided into two parts, one of which is used for the slaking of lime by adding to it all the unslaked lime needed for the causticizing process, and that, following slaking, the two volumes are brought together for the actual causticizing reaction involving the total amount of lye needed. The present invention provides the advantage that the amount of lye needed is smaller, and so the temperature can be increased.

Abstract: The invention relates to the recovery of chemicals from waste liquor from wood pulp process, primarily black liquor, while utilizing energy liberated. Controlled total vaporization of the pulp waste liquor at high temperature and low oxygen potential is achieved by the external supply of energy. During the subsequent condensation and separation a melt or water solution is obtained which, without causticizing, can be used for the preparation of white liquor, and also an energy rich gas and mainly free from sulphur, consisting primarily of carbon monoxide and hydrogen.

Abstract: Operation of a multiple solids fluidized-bed black liquor combustor employing only combustion residue solids as both fine and coarse bed solids is disclosed. Under normal operating conditions, a solids distribution of fine particle sizes and coarse particle sizes with a minimal population of intermediate particle sizes is maintained. Heat and chemical values are readily recovered from the black liquor and the necessity for separation of the combustion residue salts from inert fluidized-bed solids is avoided.