Abstract: A process for the reductive dehalogenation of halogenated aromatics. The process comprises reacting halogenated aromatics with sodium or calcium in the presence of a lower alcohol selected from the group comprising methanol, ethanol or isopropanol and mixtures thereof in order to convert the halogenated aromatics to hydrogenated aromatics. The halogenated aromatics are preferably reacted with sodium in the presence of methanol under reaction conditions whereby said sodium is in molten form. The preferred starting sodium/methanol/halogen molar ratio ranges from 30-40/15-20/1. The process is particularly useful for dechlorinating polychlorinated biphenyl found in electrical transformer oil.

Abstract: Lithium metatungstate as a new composition of matter and the production thereof are disclosed. A solution of lithium monotungstate is treated with an extractant to remove sufficient lithium ions to produce a dilute solution of lithium metatungstate and the dilute solution is then concentrated. Lithium metatungstate solutions are more dense than other alkali metal metatungstates and have lower viscosities which properties make the solutions highly useful for heavy media separations.

Abstract: A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels which contain rare earth and noble metal fission products. The oxide fuel is reduced with Ca metal in the presence of CaCl.sub.2 and a Cu--Mg alloy containing not less than about 25% by weight Mg at a temperature in the range of from about 750.degree. C. to about 850.degree. C. to precipitate uranium metal and some of the noble metal fission products leaving the Cu--Mg alloy having transuranium actinide metals and rare earth fission product metals and some of the noble metal fission products dissolved therein. The CaCl.sub.2 having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein is separated and electrolytically treated with a carbon electrode to reduce the CaO to Ca metal while converting the carbon electrode to CO and CO.sub.2. The Ca metal and CaCl.sub.2 is recycled to reduce additional oxide fuel.

Abstract: Fe(III) complexes having high bulk density and a process for the production of the same without the generation of heavy metal-contaminated effluents are disclosed. Solid complexes of EDTANaFe and EDTAKFe having high bulk densities are formed by reaction with ferric sulfate containing low chromium levels, followed by total drying of the resulting mixture in the same processing equipment without the prior separation of the sulfate salts formed.

Abstract: A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels which contain rare earth and noble metal fission products. The oxide fuel is reduced with Ca metal in the presence of CaCl.sub.2 and a U-Fe alloy containing not less than about 84% by weight uranium at a temperature in the range of from about 800.degree. C. to about 850.degree. C. to produce additional uranium metal which dissolves in the U-Fe alloy raising the uranium concentration and having transuranium actinide metals and rare earth fission product metals and the noble metal fission products dissolved therein. The CaCl.sub.2 having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein is separated and electrolytically treated with a carbon electrode to reduce the CaO to Ca metal while converting the carbon electrode to CO and CO.sub.2. The Ca metal and CaCl.sub.2 is recycled to reduce additional oxide fuel.

Abstract: A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800.degree. C. to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein.

Abstract: Disclosed is a method of removing sulfate ion from an aqueous sodium chlorate liquor. A crystallization temperature is selected between about -15.degree. and about 0.degree. C. and the maximum concentration of sodium chlorate that is soluble in the liquor at that temperature is determined. The liquor is diluted so that the concentration of sodium chlorate in the liquor is less than that miximum concentration and the liquor is cooled to that temperature so that the sulfate ion in the liquor crystallizes as sodium sulfate decahydrate but the sodium chlorate does not crystallize.

Abstract: A soluble salt (sodium sulfate or sodium borate (Na.sub.2 SO.sub.4 or Na.sub.2 B.sub.4 O.sub.7) contained as the main component in a concentrated radioactive waste liquid generated in the BWR power plant or the PWR power plant is insolubilized and precipitated, sodium hydroxide (NaOH formed in the insolubilization is separated from the precipitate and the radioactive waste liquid slurry containing the precipitate is solidified with a hydraulic solidifying material. Since the separated caustic soda (NaOH) is free of radioactive substances, it can be easily utilized again, and since the radioactive substances are stably fixed in the solidified body, leakage of radioactivity from the solidified body can be greatly reduced.

Abstract: A process for treating potassium chloride, wherein the potassium chloride is dissolved in an aqueous medium and resulting solution is heated to evaporate water contained therein.

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: In flue gas desulfurization, sorbent promoters are recovered by mixing collected particulates with water to form a slurry. The slurry is dewatered and wet solids are disposed. The recovered material contains water soluble desulfurization promoters and is reinjected in a flue gas desulfurization humidification system. The recycle allows recovery of water soluble promoters and reduces consumption. In addition, for promoters having undesirable disposal characteristics, the system improves the disposal characteristics of the waste solids.

Abstract: A material is, herein disclosed for collecting radionuclides and heavy metals that comprises an acrylic fiber element having MnO.sub.2 and/or ferrocyanide compound of the formula K.sub.2 M.sup.II [Fe(CN).sub.6 ] (wherein M.sup.II is a divalent metal such as cobalt, zirconium, zinc or nickel) supported thereon. The material of the present invention is used in collecting and concentrating radionuclides present in liquid radioactive wastes discharged from nuclear power plants and other facilities using radioisotopes such as hospitals and non-destructive testing laboratories. The material is also used in collecting and concentrating radionuclides and heavy metals present in the seawater, rivers and industrial waste-water.

Abstract: Undesired nitrites are formed during the treatment of salt bath nitrided structural components of iron and steel in nitrate containing cooling baths, and they must be removed from the washing water. The build-up of nitrites can be avoided by oxidizing the nitrite in the salt bath into nitrate by passing air into the cooling bath during off-times.

Abstract: A feedforward control system for a multiple-effect evaporator is provided wherein control is based on maintaining desired values for inferential variables of concentration and boiling point rise for a solution of a solid inorganic substance.

Abstract: The present invention provides a process for manufacture of potassium nitrate from potassium chloride and nitric acid. A source of potassium chloride may be screened and separated into fine and coarse fractions, or the screening may be eliminated and the source may be separated into equal coarse fractions. The coarse fraction, when screening has occurred, or one of the equal fractions, where no screening has occurred, is dissolved in a dilute solution of nitric acid prior to any reaction. Thereafter, either the fine fraction (if screening occurred) or the other equal fraction (if no screening occurred) reacts with the dilute nitric acid-potassium chloride solution and additional nitric acid having a concentration of about 60% at ambient temperature. The resulting solution may be crystallized with or without the prior separation of solid potassium nitrate. Nitric acid is recovered by solvents from a residual brine solution after crystallization.

Abstract: Cesium is recovered from a cesium-bearing mineral such as pollucite by roasting with an alkaline flux to convert the cesium to a soluble salt, extracting the cesium salt with water, and separating the cesium solution from the residual solids. Water-soluble permanganate is then added to the cesium solution to selectively precipitate cesium permanganate, giving other soluble metal compounds in solution. Cesium permanganate of high purity is recovered by separation from the residual solution. The cesium permanganate can be converted to other cesium compounds.

Abstract: Metal trithiocarbonates such as Na.sub.2 CS.sub.3 are useful depressant for such sulfided minerals as copper and iron sulfides in molybdenum recovery.

Abstract: The invention relates to the treatment of brine and more particularly the treatment of the brine elutriate drawn off after evaporation of the brine at an elevated temperature to separate some of the sodium chloride thereon. The crude brine normally contains sodium sulphate and potassium chloride, sometimes to relatively high levels, and the invention is directed primarily at the separation out of these salts. To achieve this, the brine elutriate is cooled, in chamber (12) whereby an NaCl--/KCl--/Na.sub.2 SO.sub.4 -- salt mixture is separated off by crystallization. The remaining parent solution can be returned to the evaporation stage (10), without disturbing the equalized balance of the secondary salts in the brine to be processed. The NaCl present in the salt mixture can be recovered by deposition with refrigerated water and separation of the Na.sub.2 SO.sub.4.

Abstract: In a treatment of carnallitic ores by treatment with a decomposition-brine containing amounts of MgCl.sub.2, KCl and NaCl suitable for precipitating artificial sylvinite in a solution of MgCl.sub.2 saturated in KCl and NaCl, the improvement of adding to said decomposition-brine a collector, e.g., a fatty amine acetate, for the flotation of KCl and a source of gas, preferably a gas-liberating additive such as H.sub.2 O.sub.2, so as to contact newly formed crystal nucleii of KCl selectively with said collector and to contact bubbles of said gas with said collector so as to form a froth enriched in KCl simultaneously with the decomposition of said carnallite, the process being particularly useful for treatment of underground carnallitic ore whereby the froth and brine are withdrawn at the surface, separated, and the brine, after make-up additions, is recycled to the ore formation.

Abstract: The invention relates to a method for recovering sodium chemicals from green liquor by precarbonating green liquor by means of flue gases, by bringing a precarbonated solution into contact with a sodium bicarbonate solution and by stripping hydrogen sulphide from the so obtained reaction mixture by means of steam, for producing hydrogen sulphide gas and a sodium carbonate solution, which sodium carbonate solution is so pure, in relation to sodium sulphide that it can directly be led into the washing of the flue gases and into a carbonation stage, for producing the sodium bicarbonate solution.

Abstract: Cesium is recovered from cesium alum, CsAl(SO.sub.4).sub.2, by a two-reaction sequence in which the cesium alum is first dissolved in an aqueous hydroxide solution to form cesium alum hydroxide, CsAl(OH).sub.3, and potassium sulfate, K.sub.2 SO.sub.4. Part of the K.sub.2 SO.sub.4 precipitates and is separated from the supernatant solution. In the second reaction, a water-soluble permanganate, such as potassium permanganate, KMnO.sub.4, is added to the supernatant. This reaction forms a precipitate of cesium permanganate, CsMnO.sub.4. This precipitate may be separated from the residual solution to obtain cesium permanganate of high purity, which can be sold as a product or converted into other cesium compounds.

Abstract: A process for removing dissolved aluminum and silica contaminants from concentrated alkali metal halide brines used in membrane electrolytic cells is disclosed. The process involves contacting an acidified brine at a pH of between about 2.0 and about 3.0 with a strong macroreticular cationic chelating resin.

Abstract: Cesium is recovered from a cesium-bearing mineral such as pollucite by extraction with hydrochloric acid to obtain an extract of cesium chloride and other alkali metal and polyvalent metal chlorides. The iron and aluminum chlorides can be precipitated as the hydroxides and separated from the solution of the alkali metal chlorides to which is added potassium permanganate or other water-soluble permanganate to selectively precipitate cesium permanganate. The cesium precipitate is then separated from the residual solution containing the metal chlorides. The cesium permanganate, which is in a very pure form, can be converted to other cesium compounds by reaction with a reducing agent to obtain cesium carbonate and cesium delta manganese dioxide.

Abstract: Disclosed is a process for making potassium ferrate (K.sub.2 FeO.sub.4) by reacting substantially pure KOH, C1.sub.2, and a ferric salt in the presence of a stabilizing proportion of at least one ferrate-stabilizing compound (e.g., a combination of an alkali metal silicate and an alkali metal iodine-containing salt). The formed K.sub.2 FeO.sub.4 is separated and recovered from other reaction co-products [KCl, H.sub.2 O, KOCl, and Fe(OH).sub.3 ] and excess KOH. Other specific improvements include the following:(i) returning KCl co-product back to a chlor/alkali membrane-type electrolytic cell and then making very pure KOH and Cl.sub.2 ;(ii) recylcing excess KOH back to the ferrate-forming reaction; and(iii) recovering a substantially pure dry solid K.sub.2 FeO.sub.4 product by washing the above-noted K.sub.2 FeO.sub.4 product in DMSO or its equivalent; and then washing with methanol or its equivalent, before drying.

Abstract: Novel sequestering agents useful for the extraction of metal values and in various organic syntheses comprise a cross-linked organic polymeric substrate, said substrate having covalently coupled thereto a plurality of functional groups, the free valence of which having the structural formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.6 and R.sub.7, which are identical or different, each represents a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, R.sub.5 and R.sub.8, which are also identical or different, each represents a hydrogen atom, an alkyl or cycloalkyl radical having 1 to 12 carbon atoms, a phenyl radical, a --C.sub.g H.sub.2q --.phi. or C.sub.q H.sub.2+1 --.phi.-- radical, and further wherein q ranges from 1 to about 12, and n, m and p, which are also identical or different, range from 1 to 10, and .phi. is phenyl.

Abstract: A method to purify an aqueous solution of an alkali metal hydroxide by countercurrently contacting the ammonia and hydroxide, in a volume ratio of about 0.6 to 1 to about 1 to 1, in a packed bed. The temperature in the lower portion of an extractor in which the process is carried out is controlled and maintained within a range of at least about 155.degree. to about 170.degree. F.

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: The invention relates to an open dissolving chamber for rock salt and to a process for the production, free from vapors, of concentrated, aqueous sodium chloride crude brine by continuously dissolving rock salt in this dissolving chamber. The dissolving chamber contains a heap of rock salt with which the brine which is unsaturated in respect of salt comes into contact. The brine thereby becomes saturated with sodium chloride and then passes out of the dissolving chamber. In the present process, the unsaturated brine enters at the base of the dissolving chamber. The saturated crude brine is removed from the rock salt through at least one vertical or inclined screen which largely holds back suspended rock salt particles. The liquid level of the saturated crude brine in the dissolving chamber should not reach the surface of the heap of rock salt, and the side of the screen facing the interior of the dissolving chamber should be completely covered with a mixture of saturated crude brine and rock salt.

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: N-substituted perhydro-s-triazine compounds can be used to increase the solubility of alkali or alkaline earth metal salts in an organic medium. Increasing the solubility of such salts catalyzes the reaction between the salts and other components of the organic medium. For example, 5 percent of a tris(n-octylpolyoxyethylene)-N,N',N"-perhydro-s-triazine compound catalyzes the reaction between sodium iodide and n-octyl bromide at 80.degree. C. for 1 hour to form 100 percent yield of n-octyl iodide.

Abstract: Potassium ferrate (VI), K.sub.2 FeO.sub.4, which has been crystallized from a concentrated aqueous solution of KOH is washed with an aqueous solution of a potassium salt of an inorganic acid to remove the residual KOH. The wash solution is at an alkaline pH and contains a high concentration of the potassium salt.

Abstract: A process and installation for the integrated treatment of concentrated residual solutions resulting from the anodization of aluminium parts is described, in which caustic soda is employed in the pickling process and sulphuric acid in the anodization bath.The process comprises three sets of operations:(1) Production of aluminium sulphate in concentrated solution or in hydrated crystals, by the treatment of part of the residual solution from the anodization.(2) Production of precipitated aluminium hydroxide and a solution of sodium sulphate from residual anodization and pickling solutions.(3) Production of sodium aluminate from residual pickling solutions and aluminium hydroxide producted in (2). (FIG. 1.

Abstract: A method and apparatus for safely and economically converting sodium sludge and other dangerous wastes containing metallic sodium, lithium and potassium into products of economic value. The process reacts solid or molten wastes with an aqueous solution to yield products of the metal hydroxides, hydrogen gas and waste heat while consuming only water. Both scrap sodium and sodium sludge are acceptable feedstocks for this unique float/spray process.

Abstract: Methods and apparatus are disclosed for enhanced purification of caustic soda solutions. In place of conventional mechanical separators, flotation separation methods are taught utilizing sequential multi-temperature sparging gas treatments. A first stage treatment, at about 70.degree. F.-90.degree. F., provides separation of sodium chloride and a subsequent stage, higher temperature (about 90.degree. F.-100.degree. F.) treatment provides enhanced removal of suspended sodium sulfate. Sensible heat is added to sparging gas to offset the cooling effect of gas expansion in a treatment tank and avoid crystallization of dissolved impurities from saturated solutions on sparging gas nozzles.

Abstract: A process for reducing the sodium chloride content of crystalline potassium salts without the use of successive recrystallization. The crystalline potassium salts having a sodium chloride content greater than about 0.8 percent by weight are subjected to compacting and crushing to provide a crystalline product having an average particle diameter less than 1.6 millimeters. The crystalline product is leached with a brine at least about 80 percent saturated with said potassium salt and less than 50 percent saturated with sodium chloride to produce a crystalline potassium salt product containing less than about 0.35 percent by weight of sodiumchloride.

Abstract: A process for selectively removing sodium sulfate and sodium hydroxide from an aqueous slurry containing sodium chloride, sodium sulfate and sodium hydroxide, which comprises contacting the slurry in a countercurrent wash step with cool water to remove sodium sulfate and sodium hydroxide therefrom.

Abstract: There is provided a process for treating air-borne dust containing silicon dioxide in order to form a silicic acid or a silicate. The air-borne dust is dissolved in an alkali metal hydroxide solution to form an alkali metal silicate solution. The alkali metal silicate solution is purified by treating it with activated charcoal and/or oxidation agents. Non-decomposable substances remaining after the purification step are removed from the alkali metal silicate solution. The alkali metal silicate solution is then reacted with acids and/or salts of aluminum, magnesium and calcium. The resulting product is then filtered, washed and dried, and then comminuted to form a finely divided, amorphous, substantially pure, precipitated, silicic acid or silicate having a whiteness according to Berger at a wave length of 460 m.mu. of about 90 to about 95% and a specific surface area of about 30 to about 800 m.sup.2 /g BET.

Abstract: A process for safely and conveniently disposing of active metal residue, such as a mixture of alkali metal and alkaline earth metal, by introducing the residue into a furnace in which it is completely transformed into harmless metal salts or oxides, which can be disposed of safely and inexpensively.

Abstract: The present invention relates to a process for the production of potassium chloride and of magnesium chloride hexahydrate (bischoffite) from carnallite or from carnallite containing sodium chloride.The process comprises heating carnallite at a temperature of between above 70.degree. C. and above 167.5.degree. C. in the presence of added water at the above former temperature or without added water (but preventing evaporation of water) at the above latter temperature. Solid potassium chloride is then separated. In the residual brine, carnallite is precipitated by evaporation or by lowering the temperature, and it is recycled to the starting stage. The residual solution consists essentially of magnesium chloride which is recovered as bischoffite.

Abstract: A fully integrated process is provided for the recovery of valuable components from waste materials generated in electrolytic aluminum reduction systems. The waste materials, such as spent pot linings, channel and trench cleanings, floor sweepings and spent alumina from offgas purifying dry scrubbers, are combined, then pyrohydrolyzed at elevated temperature. Fluoridic values, such as NaF and HF can be recovered from the offgas generated by pyrohydrolysis, while alumina and Na.sub.2 O values, or if desired, sodium aluminate, is reclaimed from the solid residue of pyrohydrolysis.The fluoridic values from the pyrohydrolysis offgas can be used for the manufacture of both electrolytes for aluminum reduction cells and also for the production of anhydrous HF. The alumina from the pyrohydrolysis residue can be reclaimed by a Bayer process-type leach with a caustic solution and the recovered high purity alumina utilized, for example, as reduction cell feed and/or for scrubbing reduction cell offgases.

Abstract: The content of sodium sulfate (and less soluble sulfates) in rock salt (halite) can economically be reduced from levels as high as 5 weight percent to levels as low as about 0.1 weight percent by the process of the invention. The halite is crushed to a certain particle size range and particles less than 0.5 mm in effective diameter are removed while (or after) the crushed material is subjected to attrition washing with a low sulfate, high NaCl brine. The washed, coarse particles are rinsed with a low sulfate brine, drained and dried to an extent appropriate to their contemplated use.

Abstract: An aqueous solution of sodium hydroxide containing soluble impurities such as a concentrated catholyte produced by a diaphragm electrolysis is cooled by a coolant or a heat-exchanger to form a slurry containing sodium hydroxide hydrate crystals and fine impurity crystals. The fine impurity crystals are adsorbed on bubbles which are formed by vaporizing a dissolved coolant or introducing a gas in the slurry and separated from the slurry.

Abstract: Carnallite, comprising principally of MgCl.sub.2. KCl.6H.sub.2 O, with varying amounts of sodium chloride and other impurities, is dissolved in a lower saturated monohydric aliphatic alcohol having from one to four carbon atoms such as methanol, ethanol, propanol, isopropyl alcohol, N-butyl alcohol, secondary-butyl alcohol, iso-butyl alcohol, and tert-butyl alcohol, to dissolve the magnesium chloride therein leaving an insoluble residue of principally potassium chloride, sodium chloride and other materials. The residue is filtered from the solution, dried and stored or further processed. The filtrate, a magnesium chloride hydrate solution is further processed by injecting steam or water into the solution and removing, e.g., evaporating the methanol from the solution leaving an aqueous magnesium chloride hexahydrate brine. The recovered methanol is dried by distillation, condensed and recycled.

Abstract: Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam-CO.sub.2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps.

Abstract: Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level.

Abstract: A process is disclosed for separating antimony sulfides from solutions comprising anitmony sulfides and arsenic sulfides by subjecting the solution to partial oxidation within prescribed pH limits in order to oxidize and precipitate a substantial portion of the antimony sulfides while leaving substantially all of the arsenic sulfides in solution.

Abstract: Chrome saltcake has stable free flowing properties imparted to it by subjecting the sodium dichromate impurity present in chrome saltcake to reaction to form a product that is less susceptible to absorption of moisture than sodium dichromate.

Abstract: An aqueous solution of sodium hydroxide containing soluble impurities such as a concentrated catholyte produced by a diaphragm electrolysis is cooled by a coolant or a heat-exchanger to form a slurry containing sodium hydroxide hydrate crystals and fine impurity crystals. The fine impurity crystals are adsorbed on bubbles which are formed by vaporizing a dissolved coolant or introducing a gas in the slurry and separated from the slurry.

Abstract: Cesium is recovered from cesium alum, CsAl(SO.sub.4).sub.2, by a two-reaction sequence in which the cesium alum is first dissolved in an aqueous hydroxide solution to form cesium alum hydroxide, CsAl(OH).sub.3, and potassium sulfate, K.sub.2 SO.sub.4. Part of the K.sub.2 SO.sub.4 precipitates and is separated from the supernatant solution. In the second reaction, a water-soluble permanganate, such as potassium permanganate, KMnO.sub.4, is added to the supernatant. This reaction forms a precipitate of cesium permanganate, CsMnO.sub.4. This precipitate may be separated from the residual solution to obtain cesium permanganate of high purity, which can be sold as a product or converted into other cesium compounds.

Abstract: Disclosed is a method for producing hydrotalcite in high yield including reacting activated magnesia with an aqueous solution containing aluminate, carbonate, and hydroxyl ions. The .[.method further includes a first step of.]. .Iadd.activated magnesia is produced by .Iaddend.heating magnesium carbonate or magnesium hydroxide to a temperature between about 500.degree.-900.degree. C. .[.to form activated magnesia or magnesium oxide..]. The method is suited to producing synthetic hydrotalcite from industrial Bayer liquor.