Abstract: A procedure of minimum environmental impact and maximum lithium recovery for obtaining concentrated brines with minimal impurity content from brines that embed natural salt flats and salt marshes, the procedure wherein the following stages are comprised: a) building fractional crystallization ponds by solar evaporation; b) filling the ponds with natural brine; c) initially pre-concentrating natural brine to the maximum possible lithium concentration in the liquid phase without precipitating lithium-containing salts; d) cooling the pre-concentrated brine obtained in c) ensuring maximum precipitation of salts containing sulfate anion; e) chemically pre-treating the liquid phase of brine separated from precipitated salts by cooling to minimize sulfate anions in the liquid phase after cooling; f) finally pre-concentrating the pre-treated liquid phase to the maximum possible lithium concentration in it without precipitating lithium-containing salts; g) chemically treating the liquid phase of brine separated from p

Abstract: Provided are methods of preparing magnetite and akaganéite nanoparticles from steel slag, the nanoparticles produced therefrom, and methods of using the same as a raw material for wastewater treatment.

Abstract: Systems and methods for the use of highly reactive hydrated lime (HRH) in high temperature flue gas streams, namely those at greater than 400° F., such as are present before an air preheater (APH) to remove sulfur trioxide (SO3) from the flue gas.

Abstract: A gas-liquid contactor is obtained by including a header pipe for supplying washing water, in a direction perpendicular to a vertical axis direction, the header pipe being disposed above a packed bed contacting section through which exhaust gas moves upward and passes; and spray nozzles for discharging spray water, the nozzles being disposed, in an upward orientation, with predetermined intervals on the header pipe. The spray water that has been discharged from the spray nozzles is supplied at a low liquid flow rate. The discharged spray water becomes a liquid film and falls downward along the surface of the header pipe, and then falls and spreads in the packed bed contacting section, so that the washing water is made to contact the exhaust gas moving upward through the packed bed contacting section. Accordingly, the washing water is used to clear and remove water-soluble substances contained in the exhaust gas.

Abstract: A system and method for desulfurization or acidic gas removal from a hot flue gas is provided that uses a dry sorbent injection technology with downstream sorbent reproduction based on a dual-alkali process. As such, lime and flue gas carbon dioxide are used in a process to produce the dry sorbent, sodium bicarbonate.

Abstract: Process for the combined regeneration of at least two soluble salts contained in a residue of an industrial process comprising heavy metals, comprising: adding an amount of reactive aqueous solution needed to completely dissolve the salts which are desired to be regenerated to the residue; subjecting the resulting aqueous suspension to a separation to obtain an aqueous production solution on the one hand and insoluble impurities on the other hand, which are removed; successively subjected the aqueous production solution to at least two selective crystallization steps intended to crystallize, separately, the at least two soluble salts which are desired to be regenerated, which are washed, dried and regenerated separately; and adjusting the concentration of at least one of the soluble salts to be regenerated in the aqueous production solution, at the moment when such solution is subjected to the step of crystallization of this salt, to give rise to the selective crystallization of this salt, by addition of a co

Abstract: Methods of processing an aqueous solution comprising potassium sulfate and magnesium sulfate include crystallizing K2SO4, crystallizing recycle crystals, and mixing at least a portion of the recycle crystals with the aqueous solution. Systems for processing potassium sulfate and magnesium sulfate include a first crystallizer and a second crystallizer in fluid communication with the second mix tank. The second crystallizer is structured and adapted to precipitate recycle crystals from the concentrated liquor to form a potassium-depleted recycle brine. The recycle crystals precipitated in the second crystallizer have a composition suitable to be recycled to the first crystallizer to increase the production of SOP.

Abstract: A method of treating a wastewater is provided and can be used, for example, to treat a gas well production wastewater to form a wastewater brine. The method can involve crystallizing sodium chloride by evaporation of the wastewater brine with concurrent production of a liquor comprising calcium chloride solution. Bromine and lithium can also be recovered from the liquor in accordance with the teachings of the present invention. Various metal sulfates, such as barium sulfate, can be removed from the wastewater in the production of the wastewater brine. Sources of wastewater can include gas well production wastewater and hydrofracture flowback wastewater.

Abstract: It is possible to produce battery grade metallic lithium from naturally occurring or industrial brine by a process comprising the following steps: (i) precipitating magnesium with calcium hydroxide; (ii) removal of boron via extraction of solvents; (iii) precipitation of lithium with sodium carbonate; (iv) transformation of lithium carbonate to bicarbonate of lithium with carbonic acid; (v) decomposition of bicarbonate of lithium into high purity lithium carbonate as a result of heating of the solution. Re-precipitation of lithium carbonate by the formation of bicarbonate of lithium allows for the removal of the majority of contaminants which co-purify with lithium carbonate and yield battery grade highly purified lithium carbonate.

Abstract: The present invention resides in a process of recovering nickel and cobalt, regenerating the main raw materials, said process including the steps of: granulometric separation; leaching; neutralization; MHP production in only one stage and the pressure crystallization of magnesium sulphite. The process proposes a way to recovery nickel and cobalt from laterite ores through the atmospheric and heap leaching with staged addition of ore—by size separation—and H2SO4, decreasing the nickel losses and simplifying the neutralization circuit and producing a more purified MHP. The present process route is employed for nickel extraction, including the one from high magnesium containing lateritic ores.

Abstract: A method of treating a wastewater is provided and can be used, for example, to treat a gas well production wastewater to form a wastewater brine. The method can involve crystallizing sodium chloride by evaporation of the wastewater brine with concurrent production of a liquor comprising calcium chloride solution. Bromine and lithium can also be recovered from the liquor in accordance with the teachings of the present invention. Various metal sulfates, such as barium sulfate, can be removed from the wastewater in the production of the wastewater brine. Sources of wastewater can include gas well production wastewater and hydrofracture flowback wastewater.

Abstract: A process for recovering a target metal from an oxidized metalliferous material comprises the steps of: in an acid generation stage, adding sulfuric acid to a solution comprising a metal halide to generate an acidic aqueous halide solution; in a leaching stage that is separate to the acid generation stage, leaching the oxidized metalliferous material with the acidic aqueous halide solution to leach the target metal into solution; passing the solution from the leaching stage to a target metal recovery stage in which the target metal is recovered from the solution while the metal halide is retained in solution; and returning the solution with the metal halide therein from the target metal recovery stage to the acid generation stage.

Abstract: A three-step process for the preparation of analytical grade sodium chloride from rock salt was developed.

Abstract: Fibrous basic magnesium sulfate particles are continuously produced by the process comprising the following steps: (1) placing in a reaction vessel a seed particle-containing aqueous dispersion comprising fibrous basic magnesium sulfate seed particles dispersed in an aqueous medium; (2) supplying magnesium hydroxide and magnesium sulfate continuously into the reaction vessel under heating and stirring the seed particle-containing aqueous dispersion, whereby depositing basic magnesium sulfate produced by the reaction between the magnesium sulfate and magnesium hydroxide in the presence of water on the surfaces of the fibrous basic magnesium sulfate seed particles, to give an aqueous dispersion containing an increased amount of fibrous basic magnesium sulfate particles; (3) taking the aqueous dispersion obtained in the step (2) continuously out of the reaction vessel; and (4) recovering fibrous basic magnesium sulfate particles from the aqueous dispersion taken out of the reaction vessel.

Abstract: The present invention resides in a process of recovering nickel and cobalt, regenerating the main raw materials, said process including the steps of: granulometric separation; leaching; neutralization; MHP production in only one stage and the pressure crystallization of magnesium sulphite. The process proposes a way to recovery nickel and cobalt from laterite ores through the atmospheric and heap leaching with staged addition of ore—by size separation—and H2SO4, decreasing the nickel losses and simplifying the neutralization circuit and producing a more purified MHP. The present process route is employed for nickel extraction, including the one from high magnesium containing lateritic ores.

Abstract: This patent describes the use of barium sulfate as filler for thermosetting and thermoplastic plastics, elastomers, sealants, adhesives, fillers, varnishes, paints, paper, glass and as substrate for colored pigment formulations as well as for single-layer or multilayer coatings consisting of metal oxides, metal oxide mixtures and/or metal compounds, as a nucleus of crystallization for lead sulfate in the negative electrode paste of lead accumulators and as an X-ray contrast medium, the barium sulfate being produced by a continuous process wherein a barium salt solution and a sulfate solution are simultaneously and continuously brought together in equimolar quantities in a precipitating suspension at a temperature of 30 to 90° C., with constant stirring, the precipitating suspension is withdrawn continuously in a steady volume and the barium sulfate precipitate is filtered, washed and optionally dried, wherein the barium salt solution has a concentration of 0.1 to 0.

Abstract: A process for recovery of vanadium dissolved in acid solutions or liquors by precipitating it out as vanadium pentoxide. Separation is carried out by adding calcium hydroxide, quicklime or calcium carbonate to the acid solution or liquor, producing a precipitate of vanadium pentoxide, which is separated from the liquid by physical methods such as filtration or centrifugation. If the acid is other than sulfuric acid, the calcium which remains dissolved in the solution or liquor by the addition of calcium hydroxide, quicklime or calcium carbonate, is removed by adding sulfuric acid, to produce solid calcium sulfate and water. The calcium sulfate is extracted from the solution or liquor or liquor by filtration or centrifugation. With sulfuric acid solution or liquors, after addition of the neutralizing agent, a solid precipitate of vanadium pentoxide and calcium sulfate is formed, which is then separated from the solution or liquor.

Abstract: This invention provides a production process, which can stably produce high-quality satin white (calcium trisulfoaluminate) having very small and homogeneous particulate shapes suitable for incorporation into coated paper for printing, and an apparatus for use in said process. In this process for producing calcium trisulfoaluminate, a calcium hydroxide suspension (A) is reacted with an aqueous aluminum sulfate solution (B) to produce calcium trisulfoaluminate (C). The aqueous aluminum sulfate solution (B) is added in plurality of stages to the calcium hydroxide suspension (A). At least any one stage of the plurality of stages addition, addition of the aqueous aluminum sulfate solution (B) to the calcium hydroxide suspension (A) is carried out in such a manner that the aqueous aluminum sulfate solution (B) is continuously added to the calcium hydroxide suspension (A) being continuously transferred.

Abstract: The invention relates to synthesis of nanoparticles, in particular to methods for producing nanoparticles with networks consisting of Z sulphate (Z=magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) or the binary mixtures thereof). The inventive method consists in synthesising the nanoparticles by crystal growth from an ion Z source and a sulphate ion source in a liquid phase mixture. The invention produces Z sulphate nanoparticles having a small diameter and uniformly dispersible in water or other solvents in a simple way. Co-ordinating solvents like glycerine, glycol ethylene and other polyethylene glycols, polyalcohols or dimethylsulphoxide (DMSO) are used for the synthesis mixture.

Abstract: The present invention provides methods and apparatus for treating flue gas containing sulfur dioxide using a scrubber, and more particularly relates to recovering gypsum and magnesium hydroxide products from the scrubber blowdown. The gypsum and magnesium hydroxide products are created using two separate precipitation reactions. Gypsum is crystallized when magnesium sulfate reacts with calcium chloride. Magnesium hydroxide is precipitated when magnesium chloride from the gypsum crystallization process reacts with calcium hydroxide. The process produces a high quality gypsum with a controllable pH and particle size distribution, as well as high quality magnesium hydroxide.

Abstract: The present invention relates to recovery of industrial grade potassium chloride and low sodium edible salt from bittern as part of an integrated process. The process comprises, mixing low sulphate concentrated feed bittern (a by-product of salt industry) of density 31.5 to 32.5° Be (sp.gr. 1.277–1.289) with high density end bittern of density 36.5 to 37.5° Be? (sp.gr. 1.336–1.35), thereby producing low sodium carnallite, from which industrial grade potassium chloride is produced. The resultant bittern is evaporated in forced evaporation system, thereby producing crude carnallite, from which low sodium salt that would be beneficial to persons suffering from hypertension is produced. When sulphate-rich bittern is used, such bittern is desulphated with CaCl2 that is generated from carnallite decomposed liquor through reaction with lime, and wherein low B2O3-containing Mg(OH)2 is a by-product. The entire content of potassium in feed bittern is recovered in the process of the invention.

Abstract: Methods and apparatus for the production of low sodium lithium carbonate and lithium chloride from a brine concentrated to about 6.0 wt % lithium are disclosed. Methods and apparatus for direct recovery of technical grade lithium chloride from the concentrated brine are also disclosed.

Abstract: A new process for recovery of Low Sodium Salt from bittern has been described in the present invention, the said process comprising desulphatation of bittern (by-product of salt industry), evaporation of bittern in solar pans and processing of solid mixture with water to produce a mixture of sodium and potassium chlorides and optionally preparing “free flowing” and iodized, by known techniques.

Abstract: A chemical process for the purification of CaSO4 utilizes the ability of an aqueous solution of a chelating agent to selectively dissolve CaSO4 in that the initial extraction can be carried out at certain pH and CaSO4 can be recovered by titration to a different pH (usually a a lower pH) following a mechanical treatment, such as centrifugation or filtration, to separate the aqueous chelate solution from insoluble material. Also claimed are an apparatus and the use of chelating agents therefor.

Abstract: The invention relates to the production of calcium compounds containing water of crystallization by means of a chemical reaction between an aqueous alkaline sodium aluminate solution and solid or dissolved or suspended calcium (hydr)-oxide in the presence of carbon dioxide or carbonate; and to the use of these compounds. The resulting precipitate is separated by sedimentation, dehydration, drying and/or clacination and/or grinding or suspending the resulting filter cake and reacted with at least one mineral acid and/or at least one salt of the same. The resulting precipitate, which contains water of crystallization, is separated by sedimentation, dehydration, drying and/or grinding.

Abstract: Processes for treating iron containing waste streams are provided. According to these processes, metal-containing compounds, particularly iron oxides are produced. These methods may, for example, be used in the processing of the waste streams from the chlorination of titanium-bearing raw materials and involve the use of certain combinations of neutralization and precipitation steps.

Abstract: A new process for recovery of common salt, potassium chloride, concentrated magnesium chloride with enriched bromide, and high purity magnesia from brine in an integrated manner, said process comprises preparation of calcium chloride by reaction of hydrochloric acid generated in the process with limestone, desulfatation of brine with calcium chloride, production of sodium chloride of superior quality in solar pans, solar evaporation of bittern thereby producing carnallite and end bittern, processing carnallite through established processes to produce potassium chloride, recovering end bittern containing highly concentrated magnesium chloride and enriched bromide and calcination of a part of the end bittern after solidification to produce high purity magnesia and hydrochloric acid utilizable in the process.

Abstract: The present invention relates to a method for the continuous separation of caesium, strontium and transuranium elements contained in sodium waste which comprises the use of NaTPB, and to a device for the implementation of this method. The method of the invention comprises, in line, the following steps: (a) filling at least one of at least two feed tanks with the waste; (b) analysis of the content of Cs+, Sr++, Na+ and transuranium elements in the waste; (c) pre-treatment, adapted in relation to analysis results, of the solution in the feed tank intended to insolubilise the strontium and transuranium elements; (e1) a first caesium separation treatment; and e1a) a second caesium separation treatment, the method being conducted in continuous manner by means of the alternate use of the feed tanks.

Abstract: A simple, effective, cost-efficient method of precipitating sulfate in an aqueous salt solution and removing the precipitate from the solution. The steps of the method include diluting the solution and slowly adding a precipitant to the solution. By following this method, a sulfate precipitate settles out of the solution quantitatively and can be easily separated from the sulfate-free supernatant.

Abstract: Process for the production of gypsum and also of an iron-oxide pigment from the waste acid that accumulates in the course of the production of titanium dioxide in accordance with the sulfate process, characterized in that in a first stage a partial neutralization of the waste acid is effected with a calcium compound subject to precipitation and optionally direct separation of gypsum, subsequently the remaining solution is neutralized further in a second stage subject to precipitation of a deposit containing Ti, Al, Cr, V and optionally Fe(III) and from the solution containing iron sulfate that is obtained after separation of the solids an iron-oxide pigment is produced in a third stage by addition of alkaline compounds and also of an oxidizing agent.

Abstract: The present invention relates to the improvement of a replenishment method of a magnesium-based compound and to the improvement of a double decomposition method, which can be used in a magnesium hydroxide desulfurization method. In the improved replenishment method, the magnesium-based compound is supplemented with water and the ratio of Mg/H2O is adjusted to the total Mg/H2O in the desulfurization system. In the improved double decomposition method, a tank for use is provided with an inner cylinder which partitions the tank into an inner part and an outer part, but does not reach the bottom of the tank, and a part of the slurry drawn through the bottom of the tank is fed to the outer upper position in the tank.

Abstract: Process for the production of gypsum and also of an iron-oxide pigment from the waste acid that accumulates in the course of the production of titanium dioxide in accordance with the sulfate process, characterized in that in a first stage a partial neutralization of the waste acid is effected with a calcium compound subject to precipitation and optionally direct separation of gypsum, subsequently the remaining solution is neutralized further in a second stage subject to precipitation of a deposit containing Ti, Al, Cr, V and optionally Fe(III) and from the solution containing iron sulfate that is obtained after separation of the solids an iron-oxide pigment is produced in a third stage by addition of alkaline compounds and also optionally addition of ammonia and also of an oxidizing agent, ammonia being liberated by addition of CaO and/or Ca(OH)2 from the solution containing (NH4)2SO4 that is obtained after separation of the iron-oxide pigment.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: Process for enriching crude salt, in which the crude salt is ground and then cooled in a saturated aqueous sodium chloride solution, to a temperature below the anhydrous sodium chloride to sodium chloride dihydrate transition temperature, a stock of a powder comprising sodium chloride crystals is collected from the cooling step and the powder is subjected to particle-size fractionation from which a fine particle-size fraction and a coarse particle-size fraction comprising the enriched salt are collected.

Abstract: Novel compositions containing at least one biologically active component derived from peat or similar composition, methods for their preparation and therapeutic uses for a variety of diseases, injuries, and conditions, including wound healing, pain, itch, inflammation, abnormal cell proliferation, or infections caused by fungal, bacterial, rickettsial or viral agents, psoriasis, allergic and other dermatitis, pruritis, eczema, actinic keratosis and similar conditions. In addition, the compositions can be used as diuretics, antiarrhythmics, and cardiac-stimulating agents, as well as for the treatment of mammalian diseases and disorders, including multiple drug resistance, cancers, asthma, rheumatoid arthritis, pain, wound healing, fungal disorders, and other inflammatory disorders. The compositions are derivable from peat or peat-related substances and may alternatively be synthetically produced.

Abstract: Low-cost, high-purity strontium nitrate that is low in Ba, Na, Ca, Cr, and other impurities and that is suitable for use in airbags or the like is provided. High-purity strontium nitrate having a Ba content of 0.01 wt % or lower, an Na content of 0.005 wt % or lower, a Ca content of 0.01 wt % or lower, a Cr content of less than 0.001 wt %, and a purity of 99.5 wt % or higher is produced by a manufacturing method comprising a first step for performing crystallization by adding nitric acid to an aqueous solution obtained by dissolving a strontium compound as a starting material, a second step for separating the resulting crystals, a third step for crystallizing the resulting separated solution, and a fourth step for separating the resulting crystals.

Abstract: Methods and apparatus for the production of low sodium lithium carbonate and lithium chloride from a brine concentrated to about 6.0 wt % lithium are disclosed. Methods and apparatus for direct recovery of technical grade lithium chloride from the concentrated brine are also disclosed.

Abstract: The invention relates to a method for the treatment of fluoboric electrolyte resulting from the processes of electro-extraction of metals such as copper and lead comprising a leaching stage with fluoboric acid, in order to recycle said fluoboric acid to be recirculated to said leaching stage devoid of impurities of metals such as Me=Fe, Zn, Ca, Mg, Cd, characterized in that it comprises the stages of: a) treating said fluoboric electrolyte comprising Cu(BF4)2 or Pb(BF4)2 with H2S in order to precipitate CuS or PbS respectively in accordance with the reactions Cu(BF4)2+H2S=>CuS+2HBF4  (1) Pb(BF4)2+H2S=>PbS+2HBF4  (2) thus obtaining a solution of HBF4 containing the fluoborates of said metals Me, said solution being separated, b) treating said Me fluoborates with H2SO4 in accordance with the reaction 2 Me(BF4)n+n H2SO4=>Me(SO4)n+2n HBF4  (3) (where Me=Fe, Zn, Ca, Mg, Cd) it being possible for said sulp

Abstract: A process of treating spent potliner material from aluminum reduction cells and recovering useful products. In the process of the present invention, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. As a result of this step, a gas component is produced which includes hydrogen fluoride, silicon tetrafluoride and hydrogen cyanide. Also, a slurry component is produced which includes carbon, a refractory material including silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the silicon tetrafluoride to fumed silica, hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas.

Abstract: A clear solution and a method for preparing the solution which has a pH in the range of from 10 to 13.9 and containing sulfate ions in a concentration range less than 500 parts per million. The solution is prepared by mixing two solutions in which one solution has one equivalent of magnesium sulfate and an equivalent of sulfuric acid and the second solution has an equivalent of Ca (OH).sub.2 and two equivalents of K.sub.2 OH. It is believed that CaSO.sub.4 precipitates in the mixed solution and causes coprecipitation of potassium, perhaps as double salt with the Ca leaving OH stabilized by hydration and magnesium ions.

Abstract: Control of sulfate and perchlorate impurity levels is provided in a procedure for manufacturing crystalline sodium chlorate by electrolyzing an aqueous solution of sodium chloride and crystallizing sodium chlorate from the resulting aqueous solution of sodium chlorate and sodium chloride. The mother liquor from the crystallization, or a portion thereof, is treated simultaneously with calcium chloride to remove sulfate ions by precipitating calcium sulfate and with potassium chloride to remove perchlorate ions by precipitating potassium perchlorate.

Abstract: The present invention describes a process to reduce the volume and/or weight of magnesium slag when the magnesium slag contains radioactive thorium. The process contacts the magnesium slag as an aqueous slurry with an acid in a pH range from about 4.0 to about 8.0, preferably from about 5.0 to about 5.5, followed by separating insoluble solids from the aqueous solution. Optionally, the acid digested solids are heated, either before or after the acid digestion, at a temperature from about 350.degree. to about 500.degree. C. The solid waste can then be further compacted, if desired, prior to disposal.

Abstract: In a process for removing sulfur dioxide from a gas stream using an aqueous solution of magnesium scrubbing components and subsequent oxidation of the magnesium sulfite produced which is regenerated by addition of lime, a pure magnesium hydroxide product is produced using less oxidation energy requirements by passing a further portion of solution from the oxidizing unit to a further oxidizing unit, oxidizing the same to produce an aqueous solution containing less than 130 ppm sulfite, treating the further portion with lime and separating purified magnesium hydroxide therefrom.

Abstract: This invention relates to the preparation of cesium salts from cesium-aluminum-alum in a process in which the cesium-aluminum-alum is reacted in a single vessel in the presence of water with calcium hydroxide in an amount which is equimolar to the amount of aluminum and with a readily water-soluble calcium salt in an amount which is equimolar to the amount of cesium and the precipitated aluminum hydroxide and the precipitated calcium sulfate are separated by filtration or centrifugation.

Abstract: A process for producing hydrogen and/or hemihydrate calcium sulphate from calcium sulphite. Waste solid containing calcium sulphite and other calcium salts is treated by the addition of aqueous sulphur dioxide solution or sulphuric acid solution to produce a liquid phase product. The liquid phase product may be separated from any remaining solid phase material and then subjected to the addition of sulphuric acid in a second step, wherein calcium sulphate hemihydrate is produced. The addition of sulphuric acid to the liquid phase results in the evolution of sulphur dioxide which may be used as such or in sulphur dioxide electrolysis cells in order to produce hydrogen and sulphuric acid. An especially unique feature of the process is that the sulphuric acid produced in generating hydrogen can be recycled to the step where the calcium sulphate crystals are produced.

Abstract: A process for removing chromium from an aqueous electrolyte solution is disclosed. The process involves admixing with the solution an amount of a chromium-reducing compound and an amount of a precipitant for the anion of the chromium-reducing compound. The invention provides for substantially complete reduction of hexavalent chromium to trivalent chromium and the formation of an insoluble chromium-containing material without leaving unwanted ions in the aqueous electrolyte solution. The aqueous electrolyte solution is regenerated by adjustment of pH and electrolyte concentration.

Abstract: The invention relates to a method for separating sulphate from an aqueous electrolyte in an alkali metal chlorate process, thereby reducing the operating cost and increasing the possibility of further closing the electrolytical production of alkali metal chlorate. Calcium ions are added to a portion of the electrolyte, for precipitating calcium sulphate. By adjusting the pH within the range of from 4.6 up to about 7, and combining the temperature, content of ions and the molar ratio between sulphate and calcium ions added in a suitable manner, the calcium sulphate will precipitate predominantly as gypsum and essentially without inclusions and/or co-precipitation of chromium-containing compounds or chlorate. The precipitate is subsequently removed from the portion of electrolyte, whereafter the thus purified portion of electrolyte is recycled to the chlorate process.

Abstract: A method for treating residues of barium sulfide or strontium sulfide leaching with waste sulfuric acid and hydrochloric acid, which method significantly decreases the amount of residual material which must be disposed of.

Abstract: A treatment process is provided for removing a scale-forming inorganic salt from a produced brine having a scale inhibitor and the inorganic salt dissolved therein. The process is initiated by adding an interfering agent to the produced brine which disrupts the function of the scale inhibitor, thereby enabling formation of an insoluble inorganic salt precipitate. The precipitate is readily separable from the aqueous brine.

Abstract: Disclosed is a process for treating waste sulfuric acid generated from a process for producing titanium dioxide pigment by treating titanium slag with sulfuric acid. The waste acid is treated in a first step with a calcium-containing material to produce a gypsum suspension which is filtered and from which a filtrate is recovered. The filtrate is treated in a second step with a calcium-containing substance and clarification solids from the treatment of the titanium slag with sulfuric acid. A precipitate is produced in this second step which is subsequently filtered. The precipitate is suitable for disposal in a landfill.