Abstract: The addition of a small amount of hydrogen or a hydrogen-liberating compound such as a metal hydride to a caustic solution serves to suppress the corrosive effect of the solution on nickel-based surfaces. Typical nickel-based surfaces include caustic evaporator surfaces which contain a caustic solution maintained at a temperature of from about 130.degree. C. to about 180.degree. C. A preferred metal hydride is sodium borohydride which is preferably present in an amount of from about 5 ppm to about 100 ppm. Concentrated caustic solutions containing less than 0.5 ppm of nickel can be prepared by this process.

Abstract: The invention relates to an improvement in a method of regenerating alkaline or alkaline earth metal oxides or hydroxides from solution particularly in delignification processes wherein a suitable transition metal such as ferric oxide is burnt with the solution to produce a mixed oxide that is subsequently treated in hot water to regenerate the alkaline or alkaline earth metal oxide or hydroxide and precipitate the transition metal oxide. The improvement controls the presence of fines in the transition metal oxide to maintain these at an acceptable level in the fluidized bed combustion zone. This is achieved by contacting the fines with spent liquor from a delignification process. The invention also provides for the pelletization of the fine material of the transition metal oxide and spent delignification liquor can be used as a binder in the formation of such pellets.

Abstract: A process for producing particles of a non-friable eutectic mixture of sodium nitrate and potassium nitrate for solar power station use is disclosed. In one embodiment of the invention, the particles are produced by shock chilling a molten stream of mixed nitrate material and crushing the resulting flakes to a size range of between about -5 mesh and about +30 mesh. In a second embodiment, particles of this size are produced by spray granulation of a concentrated solution of mixed nitrate salts onto a fluidized bed to produce dry, free-flowing, solid spheres. In both embodiments, the particles are extremely hard, resistant to moisture pickup and adaptable to being readily shipped by bulk containers.

Abstract: In a process for manufacturing food-grade caustic such as sodium hydroxide wherein hydrazine or a derivative or salt thereof is used as a corrosion inhibitor, residual hydrazine is removed from the concentrated caustic product solution by oxidation. The oxidation of residual hydrazine is accomplished by adding to the hydrazine-containing concentrated caustic solution, which is characterized by a pH of 14 or higher, a 5- to 10-fold stoichiometric excess of hydrogen peroxide or an equivalent peroxy compound or hypochlorite.

Abstract: A purification of an aqueous solution of potassium chloride which is used for producing potassium hydroxide by an electrolysisin an electrolytic cell using a cation exchange membrane is carried out by incorporating an oxidizing reagent to remove additives as an anticaking reagent.

Abstract: In the production of pulp, the amount of ballast in the white liquor is reduced by maintaining the concentration of the green liquor, prior to causticizing thereof to convert it to the white liquor used for cooking the wood, at a level of 110.+-.20 grams per liter total titratable alkali counted as NaOH, maintaining the efficiency of the causticizing operation at 92.+-.3%, and concentrating the white liquor, prior to the cooking, by evaporation to a content of 130-200 grams per liter efficient alkali counted as NaOH.

Abstract: Process is provided for controlling the degree of causticization of white liquor in its preparation from green liquor by the addition of calcium oxide, which comprises determining the sodium carbonate concentration of green liquor fed to the causticization; determining the sodium carbonate concentration of white liquor resulting from the causticization; and controlling the degree of causticization within a predetermined range while taking both sodium carbonate concentrations into account, so as to maintain the degree of causticization of the white liquor within the range despite variations in sodium carbonate concentration of the green liquor and variations in calcium oxide content of the calcium oxide added for causticization.

Abstract: An improvement in processes for recovering aluminum from alunite ore which processes include roasting the ore to remove water of hydration, removing sulfur and potassium compounds from the roasted ore by a procedure including a first leaching step resulting in a residue and a solution containing potassium sulfate, effecting partial recovery of potassium sulfate from the solution by crystallization with some potassium sulfate being bled off from the mother liquor, converting aluminum values in the residue to alkali metal aluminates by digesting the residue with alkali metal hydroxide including a substantial amount of sodium hydroxide, removing silicon from the alkali metal aluminates leaving a waste desilication product, recovering aluminum values from the desilicated aluminates by precipitation, circulating the mother liquor from the precipitation step to digestion as contaminated sodium hydroxide is bled off, the improvement which comprises enhancing the economics of the overall process by introducing therei

Abstract: In the regeneration of alkaline liquors as used in paper pulping, a mixed oxide compound of an alkali or alkaline earth metal oxide and an oxide of Ti, Fe, Co, Ni, or Mn is formed by burning black liquor. The burning step is carried out in a fluidized bed. The mixed oxide product is washed in cold water and subsequently treated with hot water to precipitate the oxide of Ti, Fe, Co, Ni or Mn and enable recovery of the alkaline solution for recycling.

Abstract: This invention relates to the removal of substantially all of the disodium terephthalate (Na.sub.2 TA) dissolved in a dilute aqueous solution of sodium hydroxide. More particularly this invention pertains to the recovery for reuse of an aqueous solution containing 5 weight percent sodium hydroxide from an aqueous solution containing, on a weight basis, from 5 to 5.25 percent Na.sub.2 TA and 2.5 to 3.0 percent sodium hydroxide.

Abstract: H.sub.2 S and CO.sub.2 from a waste gas are absorbed in an ammoniacal or alkali metal hydroxide solution. The resultant sodium, potassium or ammonium sulfide solution is reacted with pulverized copper oxide and the resultant copper sulfide precipitate is separated and the resultant solution of increased sodium hydroxide, potassium hydroxide or ammonia content is recycled as absorbent for hydrogen sulfide and CO.sub.2. The copper sulfide is roasted to form recyclable copper oxide and product sulfur dioxide.

Abstract: In the alkaline pulping of cellulose and particularly in the step wherein green liquor is converted to white liquor by causticizing or the addition of calcium hydroxide, it has been found that the addition of any of three specially selected organic phosphonate reagents, namely, nitrilotris(methylenephosphonic acid) (Dequest 2000); 2-phosphonobutane-1,2,4-tricarboxylic acid (Bayer PBS-AM); and hexamethylenediaminetetrakis(methylenephosphonic acid) (Nalco 7691/Dequest 2051), accelerates the speed of the reaction to the right. These acid compounds and their soluble alkali metal and ammonium salts have proved effective in increasing the acceleration rate to the right of the causticizing reaction and the production of the titratable sodium hydroxideCaO+H.sub.2 O.fwdarw.Ca(OH).sub.2ca(OH).sub.2 +Na.sub.2 CO.sub.3 .fwdarw.2NaOH+CaCO.sub.3 .dwnarw.these additives give up to a 2-4% increase in causticizing conversion to NaOH when applied at 0.

Abstract: Disclosed is a catalyst and method for converting mercaptans and mercaptide compounds in aqueous alkaline solution to disulfides. Catalytic agent is a metal complex synthesized from 3,3',4,4'-benzophenonetetracarboxylic dianhydride and converted to either the alkali metal salt or to the acid form. The method for oxidizing the mercaptide compounds comprises contacting mercaptans and mercaptide compounds in aqueous alkaline solution with air in the presence of the catalyst and subsequently separating alkaline solution from the resultant disulfide compounds.

Abstract: A method of obtaining caustic soda and pure sodium chloride from an electrolytic cell liquor containing also sulfate ions including the steps of concentrating the liquor through multiple effect evaporation, cooling the concentrate obtained, separating the sodium chloride and the salt containing sulfate and recovering the caustic soda, whereby during a first stage the liquor is evaporated so as to precipitate only sodium chloride which is removed, in a second stage a solid phase is formed of sodium chloride, sodium sulfate and triple salt of caustic soda, sodium chloride and sodium sulfate, with said solid phase being contacted with a caustic soda solution of less than about 35% by weight concentration, so as to decompose said triple salt, removing the salt containing sulfate, and in a third stage the solution from the second stage is cooled to precipitate said triple salt of caustic soda, sodium chloride and sodium sulfate, which is separated from the caustic soda which does not crystallize and is removed fro

Abstract: A process for the obtention of alumina and phosphate values by the alkaline decomposition of silica-containing aluminum phosphate ores comprises reducing the ore to a particle size of from about 6 to 13 mm; calcining the ore at a temperature of from 500.degree. to 750.degree. C in order to remove water of crystallization and combined water; grinding the calcined ore to a particle size of from 20 to 60 mesh (U. S. Sieve); treating the calcined and ground ore with an aqueous solution having a concentration of from 20 to 30% by weight caustic alkali at an initial temperature of from 65.degree. to 75.degree. C; quickly filtering the hot suspension thus obtained to remove the solid silica and heavy metal oxides; adding a 50% caustic alkali solution to the filtrate in an amount sufficient to obtain a total concentration of from 10 to 15% by weight of free caustic alkali; cooling the alkaline liquor accompanied by an elutriation action in an elutriator to a temperature of from 5.degree. to 10.degree.

Abstract: Method for recovering potassium hydroxide and zinc oxide from potassium zincate solutions, characterized in that a selective solvent of potassium hydroxide, which is miscible with water, is added to the zincate solution, in that the zinc oxide precipitate thus obtained is filtered and in that the mother liquors for separating the potassium hydroxide solution from the solvent are treated. The invention applies to all electrochemical storage cell batteries having a zinc negative electrode in which it is required to purify the electrolyte with a view to scavenging it.

Abstract: This invention relates to a new and improved recovery method of chemicals from waste liquor of pulping or bleaching. More particularly, this invention relates to a method for direct recovery of sodium hydroxide from waste liquor of pulping or bleaching which is substantially free from sulfur compounds. Ferric oxide is admixed with concentrated waste liquor and thereafter the admixture is burned to form a smelt. By submerging the smelt in hot water a solution of sodium hydroxide and a ferric oxide precipitate are obtained. The precipitated ferric oxide can be reused in the mixing step.

Abstract: An improvement in processes for recovering aluminum from alunite ore which processes include roasting the ore to remove water of hydration, removing sulfur and potassium compounds from the roasted ore by a procedure including a final leaching step resulting in a residue and a solution containing potassium sulfate, effecting partial recovery of potassium sulfate from the solution by crystallization with some potassium sulfate being bled off from the mother liquor, converting aluminum values in the residue to alkali metal aluminates by digesting the residue with alkali metal hydroxide including a substantial amount of sodium hydroxide, removing silicon from the alkali metal aluminates leaving a waste desilication product, recovering aluminum values from the desilicated aluminates by precipitation, circulating the mother liquor from the precipitation step to digestion as contaminated sodium hydroxide is bled off, the improvement which comprises enhancing the economics of the overall process by introducing therei

Abstract: Spent hemi caustic effluents from cold caustic extraction of cellulosic pulps are rendered utilizable as a source of sodium hydroxide for pulp processing by heating the effluents for a period of time and at a temperature sufficient to cause the hemicelluloses in the effluents to be degraded and to substantially eliminate precipitation of the hemicelluloses onto cellulosic materials when the effluents are used.

Abstract: Useful olive-processing liquor is recovered from olive-processing waste solution by a process wherein lime, charcoal, and calcium carbonate are successively added to the olive-processing waste solution to form a mixture and the mixture is allowed to settle. The treated liquor is separated from the settled contaminants and is then immediately recyclable to process fresh olives.

Abstract: A solution of sodium sulfite or sulfide is reacted with ammonium sulfate, so as to produce a gas containing SO.sub.2 or H.sub.2 S, NH.sub.3 and H.sub.2 O, which is thereafter treated for sulfur production and NH.sub.3 recovery, and a liquid outflow containing sodium sulfate which is reacted with CO.sub.2 and NH.sub.3, in order to produce NaHCO.sub.3 and regenerate the ammonium sulfate. NaHCO.sub.3 may be converted to sodium carbonate and CO.sub.2, the latter being re-used in the process.

Abstract: A method and apparatus for cooling aqueous alkali metal hydroxide liquors such as, for example, caustic soda liquors, involving the vacuum cooling of a body of such liquor in an evaporating chamber having a overhead vapor outlet which communicates with a direct-contact barometric condenser supplied with a stream of cooled alkali metal hydroxide liquor. The cooled alkali metal hydroxide liquor has a vapor pressure below the absolute pressure of water vapor evolved from the body of liquor in the evaporating chamber and condenses the water vapor upon contact therewith. A stream of cooled concentrated alkali metal hydroxide liquor withdrawn from the evaporating chamber is, in accordance with a preferred embodiment of the present invention, further cooled and solids contained therein, such as, for example, sodium chloride crystals, are then removed in a suitable liquid-solids separation device.