Abstract: A method of treatment or purification of a molybdenum concentrate also containing copper, comprises the step of subjecting the molybdenum concentrate to pressure oxidation in the presence of oxygen and a feed solution containing copper (e.g. CuSO4) and halide (e.g. CuCl2) to produce a pressure oxidation solution containing copper and a solid residue containing molybdenum. The pressure oxidation solution may be combined with feed solution to a second pressure oxidation in which a copper concentrate is treated for the recovery of copper therefrom.

Abstract: A chemical process for detoxifying spent CCA (copper, chrome, arsenic)—treated wood, from which CCA and detoxified wood are recovered for recycling comprising the steps of (a) treating CCA-treated wood in the presence of a liquefying reagent such as an organic solvent at 100–250° C. with or without ferrous ions to form liquefied CCA-treated wood (b) adding water or an aqueous solution of an organic solvent to the liquefied CCA-treated wood with stirring to obtain an aqueous solution of liquefied CCA-treated wood (c) adding complexing or precipitating agents, such as phosphoric acid or calcium hydroxide to the aqueous solution of step (b) thereby precipitating insoluble heavy metal complexes or precipitates and forming a solution of detoxified CCA-treated wood (d) separating said heavy metal complexes or precipitates from the solution of detoxified liquefied CCA-treated wood and (e) isolating chromated copper arsenate from said heavy metal complex or precipitate.

Abstract: Provided is a cathode composition for lithium secondary battery that includes a lithium-chromium-titanium-manganese oxide that has the formula Li[Li(1-x)/3CrxTi(2/3)yMn2(1-x-y)/3]O2 where 0?x?0.3, 0?y?0.3 and 0.1?x+y?0.3, and layered a-LiFeO2 structure. A method of synthesizing the lithium-chromium-titanium manganese oxide includes preparing a first mixed solution by dispersing titanium dioxide (TiO2) in a mixed solution of chrome acetate (Cr3(OH)2(CH3CO2)7) and manganese acetate ((CH3CO2)2Mn.4H2O), adding a lithium hydroxide (LiOH) solution to the first mixed solution to obtain homogeneous precipitates, forming precursor powder that has the formula Li[Li(1-x)/3CrxTi(2/3)yMn2(1-x-y)/3]O2 where 0?x?0.3, 0?y?0.3 and 0.1?x+y?0.3 by heating the homogeneous precipitates, and heating the precursor powder to form oxide powder having a layered structure.

Abstract: The oxide materials are of the class of ternary mesoporous mixed oxide materials including lanthanum, a metal M selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu and Zn, and zirconium or cerium such a mesoporous La—Co—Zr mixed oxide material designated as Meso LCZ[x] where x is the atomic ratio (La+Co)/La+Co+Zr. They are useful as catalysts since they show high activities for hydrocarbon oxidation and good resistance against poisoning agents. These highly ordered mesoporous mixed oxides are synthesized by: preparing an amorphous solution of a La-M precursor and adding a salt of zirconium or cerium thereto; acidifying the amorphous solution in the presence of a surfactant under conditions to obtain a clear homogeneous solution; adjusting pH of the solution under conditions to form a solid precipitate; separating the solution and surfactant from the precipitate; and calcinating the precipitate.

Abstract: In a metal oxide nanoparticle and a synthetic method thereof, and in particular to maghemite (?-Fe2O3) nanoparticles usable as a superhigh density magnetic recording substance by having good shape anisotropy and magnetic characteristics, hematite (?-Fe2O3) nanoparticles usable as a precursor to the maghemite or a catalyst, maghemite and hematite-mixed nanoparticles and a synthetic method thereof, the method for synthesizing metal oxide nanoparticles includes forming a reverse micelle solution by adding distilled water, a surfactant and a solvent to metallic salt not less than trivalent, precipitating and separating gel type amorphous metal oxide particles by adding proton scavenger to the reverse micelle solution; adjusting a molar ratio of metal oxide to the surfactant by washing the gel type amorphous metal oxide particles with a polar solvent; and crystallizing metal oxide nanoparticles through heating or reflux after dispersing the gel type amorphous metal oxide particles in a non-polar solvent having a h

Abstract: A method for removing at least one of chromate and other oxy-metal ions from liquid solutions includes contacting the liquid solution with solid barium compounds as adsorbents so that the at least one of chromate and other oxy-metal ions in liquid solution are subject to an exchange reaction with the anion of solid barium compounds to produce products including at least one of solid barium chromate and oxy-metal barium compounds and are removed from the liquid solution by a liquid-solid separation operation. A method for stabilizing at least one of chromate and other oxy-metal ions that are present in liquid or sludge wastes includes mixing the liquid or sludge wastes with barium compounds in solid form, so that the at least one of chromate and oxy-metal ions are immobilized in a solidified body after curing of the mixture.

Abstract: A process for recovery of hexavalent chromium from waste streams. The method includes providing a waste stream containing hexavalent chromium, reacting a soluble non-toxic precipitating reagent with the hexavalent chromium to form an insoluble precipitating reagent-chromate precipitate, and recovering the insoluble precipitating reagent-chromate precipitate. It may optionally include reacting the insoluble precipitating reagent-chromate precipitate with an acidic solution to form an insoluble precipitating reagent precipitate and a soluble hexavalent chromium compound, and recovering the soluble hexavalent chromium compound. The process may also include reacting the insoluble precipitating reagent precipitate with a solubilizing reagent to form the soluble non-toxic precipitating reagent.

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: The present invention relates to a process for simultaneous recovery of chromium and iron from Chromite Ore Processing Residue (COPR) and more particularly, the present invention relates to an economical and environment-friendly process for recovering chromium as a chromate salt and iron as an iron salt from non-leachable Chromite Ore Processing Residue and avoids landfilling of toxic metals.

Abstract: Disclosed is a device and method of use for detecting polyvalent analytes such as antibody to the AIDS virus, utilizing an inverse sandwich method. The test device comprises a first substance having an epitope, bound to a label and capable of moving within the test device. The test device further comprises a second substance immobilized to the test device and spatially separated from the first substance. The second substance has an epitope substantially similar to the epitope of the first substance. Upon application to the test device, the polyvalent analyte binds to the first substance and moves within the test device to the location of the second substance with both polyvalent analyte and first substance are immobilized at location of the second substance. Polyvalent analyte is detected by the presence of the label at the location of the second substance. Also disclosed is a control substance for use with the device that can be used to determine completion of the test and viability of the device.

Abstract: Process for the manufacture of an aqueous sodium chloride solution, according to which a solid material comprising sodium chloride and heavy metals is dispersed in water, the aqueous medium thus obtained is alkalinized so as to precipitate the heavy metals in the form of metal hydroxides, calcium carbonate is coprecipitated with the metal hydroxides in the aqueous medium and the aqueous medium is then subjected to mechanical clarification.

Abstract: A process for recovery of hexavalent chromium from waste streams. The method includes providing a waste stream containing hexavalent chromium, reacting a soluble non-toxic precipitating reagent with the hexavalent chromium to form an insoluble precipitating reagent-chromate precipitate, and recovering the insoluble precipitating reagent-chromate precipitate. It may optionally include reacting the insoluble precipitating reagent-chromate precipitate with an acidic solution to form an insoluble precipitating reagent precipitate and a soluble hexavalent chromium compound, and recovering the soluble hexavalent chromium compound. The process may also include reacting the insoluble precipitating reagent precipitate with a solubilizing reagent to form the soluble non-toxic precipitating reagent.

Abstract: A method of treatment or purification of a molybdenum concentrate also containing copper, comprises the step of subjecting the molybdenum concentrate to pressure oxidation in the presence of oxygen and a feed solution containing copper (e.g. CuSO4) and halide (e.g. CuCl2) to produce a pressure oxidation solution containing copper and a solid residue containing molybdenum. The pressure oxidation solution may be combined with feed solution to a second pressure oxidation in which a copper concentrate is treated for the recovery of copper therefrom.

Abstract: The process chemistry during the oxidation of molybdenite concentrates in an oxygen pressure leach can be controlled by regulating the amount of ferric iron and excess sulfuric acid recycled as autoclave discharge slurry or filtrate to the autoclave feed. A computer model capable of predicting the concentration of soluble molybdenum in the autoclave discharge and based on the concentrate and recycle analyses was developed.

Abstract: A process for separating a first source of a heavy metal ion or mixtures of heavy metal ions, (Me1), from a solution comprising a complex of said Me1 and EDDS, (Me1-EDDS), by displacement of said Me1 with a second source of a heavy metal ion Me2 by addition to the solution of a salt of said Me2.

Abstract: A method for the integration of a manufacturing facility with a salt dome, which manufacturing facility is one for the production of high purity titanium dioxide using chlorine as a reactant. The metal chlorides produced as a by-product of titanium dioxide production are reacted with sodium hydroxide to produce metal hydroxide precipitates in an aqueous sodium chloride solution, which is then conducted into a reservoir of brine in a salt dome. The metal hydroxide precipitates are allowed to settle and the sodium chloride solution mixes with the brine. A portion of the brine is conducted to the surface where it is decomposed to produce chlorine, hydrogen, and sodium hydroxide. The chlorine and sodium hydroxide are recycled for use in the overall integrated process.

Abstract: Molybdenum trioxide is produced from molybdenite by a pressure oxidation process comprising of the steps of forming an aqueous slurry of molybdenite, pressure oxidizing the slurry to form soluble and insoluble molybdenum species, converting the insoluble molybdenum species to soluble molybdenum species by alkaline digestion, separating the soluble molybdenum species from insoluble residue contaminants (if present), removing the molybdenum species from the aqueous media through solvent extraction, and recovering the molybdenum values as molybdenum trioxide from the organic solvent. Low grade molybdenite concentrates, including concentrator slimes containing talc and sericite, can be used as a feed. The process produces technical grade molybdenum trioxide.

Abstract: Tungstate solutions are purified by a precipitation process followed by two anion exchange processes to reduce molybdenum and arsenic impurity content. The precipitation involves acidification of the original highly basic tungstate solution to pH of 7 to 10 without addition of precipitating agents and separates out the bulk of impurities other than Mo, As. The first anion exchange process removes As. Then a remaining filtrate from the latter process is treated with sulfides to form thiomolybdates from impurity Mo content and the thiomolybdates are then separated out from the tungstate solution in a second anion exchange process.

Abstract: Disclosed are methods for purifying solvents, by causing contaminants to be included within layers of dispersed layered materials, and then separating the restacked combined contaminant/layered material from the solvent. The methods may be utilized to remove materials suspended in the solvents, materials immiscible with the solvents, and are especially useful for separating soluble materials from the solvents within which they are dissolved. The application of these methods will be beneficial in the remediation of polluted soil and water, the desalination of water, waste oil and gray water purification, the preparation of pharmaceuticals, and many other areas.

Abstract: The present invention discloses a process for the manufacture of liquid aqueous bleaching compositions comprising hypochlorite, a strong source of alkalinity and water, said process comprising the steps of: mixing said alkali metal hypochlorite, said strong source of alkalinity and said water, adding a precipitating agent, or mixtures thereof; and thereafter separating the precipitates formed from said composition. The compositions provided by the process according the present invention are substantially free of heavy metal ions, thereby providing improved whiteness performance and/or fabric safety performance.

Abstract: The present invention discloses a process for the manufacture of liquid aqueous bleaching compositions comprising alkali metal hypochlorite, a strong source of alkalinity and water; said process comprising the steps of: mixing alkali metal hypochlorite, strong source of alkalinity and said water, separating the insoluble species formed in the first step, and thereafter adding a chelating agent capable of chelating heavy metal ions. The compositions provided by the process according to the present invention are substantially free of heavy metal ions, thereby providing improved whiteness performance and/or fabric safety performance.

Abstract: A method for producing purified MoO.sub.3 from MoS.sub.2. MoS.sub.2 is initially oxidized to generate an impure MoO.sub.3 product containing metallic contaminants and molybdenum sub-oxides. This product is then slurried with a primary water supply to yield a first slurry in which part of the contaminants are dissolved. Preferred slurry temperatures are 25.degree.-97.degree. C. The resulting solid intermediate MoO.sub.3 product is removed from the slurry leaving the dissolved contaminants. Next, the intermediate MoO.sub.3 product is slurried with a secondary water supply to yield a second slurry in which the remaining contaminants are dissolved. Second slurry temperatures of 150.degree.-250.degree. C. are employed in the presence of an oxygen-containing gas. These conditions oxidize molybdenum sub-oxides to yield MoO.sub.3. The resulting purified solid MoO.sub.3 product is then removed from the second slurry. This process is highly efficient and avoids using liquid reagents other than water (including acids).

Abstract: A method for producing MoO.sub.3 from MoS.sub.2. MoS.sub.2 is combined with water to form a slurry which is then combined with at least one oxygen-containing oxidizing gas in a reaction chamber in order to initiate oxidization and conversion of MoS.sub.2 into MoO.sub.3. The oxidization and conversion of MoS.sub.2 into MoO.sub.3 is terminated before complete conversion of MoS.sub.2 to MoO.sub.3 takes place in order to generate a solid reaction product comprising MoO.sub.3 and unreacted MoS.sub.2 in combination with a residual liquid product comprising dissolved Mo therein. The oxidization and conversion process may be terminated when about 70-95% by weight MoS.sub.2 has been converted to MoO.sub.3. Thereafter, the solid reaction product is separated from the residual liquid product and the residual liquid product combined with at least one extractant in order to generate a liquid fraction containing dissolved Mo.

Abstract: Process for the production of pure tungsten and/or molybdenum solutions from sources, such as alkaline decomposition solutions, which are contaminated with tantalum, niobium, titanium, aluminium, tin, arsenic, phosphorus and/or silicon, by application of a three stage purification process of pH reduction, anion exchange and membrane electrolysis.

Abstract: Process for recovering and re-using cobalt and tungsten from reaction liquors, in which said reaction liquors are treated:a) With an alkali-earth metal hydroxide in order to precipitate cobalt and tungsten, and the resulting precipitate is subsequently treated with a strong mineral acid in order to be able to dissolve the cobalt salt and separate it from H.sub.2 WO.sub.4 precipitate; orb) With an alkali metal hydroxide in order to precipitate and separate Co(OH).sub.2, and the resulting alkaline solution is then treated with an alkali-earth metal compound which is filtered and treated with a strong mineral acid in order to obtain H.sub.2 WO.sub.

Abstract: According to the invention there is now provided a simple method of preparing a powder containing WC and cobalt and/or nickel. APT-powder and a powder of a basic salt of cobalt and/or cobalt are mixed in water or in mixed solvents. The suspension is stirred to react at temperatures ranging from room temperature to the boiling point of the solution whereby a precipitate is formed, which precipitate is filtered off, dried and finally reduced to a metallic powder.

Abstract: Epoxidate from the molybdenum catalyzed epoxidation of an olefin such as propylene with a hydroperoxide such as ethylbenzene hydroperoxide is treated with 2 to 15 times the stoichiometric equivalent of aqueous base such as sodium hydroxide to form Na.sub.2 MoO.sub.4 and the resulting mixture is phase separated to separate an organic phase reduced in molybdenum and a net aqueous stream containing removed molybdenum, the mass ratio of the organic phase to the net aqueous stream being 450-3,000/I.

Abstract: Hexavalent chromium is removed from aqueous sodium nitrate solutions by reacting hexavalent chromium with an aqueous slurry consisting essentially of ferrous hydroxide and barium sulfate whereby the chromium is reduced to trivalent chromium and precipitated as chromic hydroxide. Adulterating compounds and unwanted ions are not introduced to the electrolytic solution.

Abstract: A process for recovering tungsten as an ammoniacal tungstate which comprises reacting a tungsten containing material with sodium hydroxide to produce sodium tungstate and forming a first aqueous sodium tungstate solution therefrom, crystallizing sodium tungstate from the first aqueous sodium tungstate solution, dissolving the resulting sodium tungstate crystals in an aqueous medium to form a second aqueous sodium tungstate solution, extracting tungsten from the second aqueous sodium tungstate solution with an organic extracting agent wherein the extracting agent containing tungsten is capable of being stripped of the extracted tungsten by ammonia, and thereafter stripping the extracted tungsten from the organic extracting agent with ammonia to form an ammoniacal tungstate solution, crystallizing a portion of the tungsten contained in the ammoniacal tungstate solution to form a two phase system wherein an ammoniacal tungstate compound comprises the first phase and wherein the resulting mother liquor containing

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: A process for purifying an acidic technical-grade iron chloride solution formed from cyclone dust from the production of TiO.sub.2 in accordance with the chloride process by adjusting the pH with a first neutralizing agent and thereafter introducing the pH adjusted solution in a controlled manner into a solution containing a second neutralizing agent. In this process undesired ions which are to be separated, such as chromium, vanadium, zirconium and/or niobium, precipitate in the form of efficiently filterable hydroxides which can be separated industrially under economical conditions by filtration. The filter cake is non-hazardous and can safely be disposed of by dumping. Calcium carbonate is the preferred neutralizing agent, and the pH adjustment may also advantageously be effected by using scrap iron or by using iron sinters with reduction of any Fe(III) ions before the second neutralization step.

Abstract: An improved method and apparatus for treating chromium containing leather scrap to recover chromium compounds and to produce a protein hydrolysate. The leather scrap is fed into an upstream mixing zone of a reaction vessel along with an alkali metal solution and the scrap and the solution are mixed by a plurality of kneading paddles carried by a rotating shaft. The mixture is then passed to a downstream hydrolyzing zone and conveyed through the hydrolyzing zone by a spiral flight. The mixture is heated by the injection of steam to thereby produce a hydrolyzed mixture comprising a protein hydrolysate containing suspended, insoluble particles of chromium compound. The hydrolysate is separated from the precipitated chromium compounds and can be recirculated to the reaction vessel while the chromium compounds can be recovered for use in the tanning process. The concentrated hydrolysate can be subjected to electrophoresis to increase the concentration of any desired amino acid in the hydrolysate.

Abstract: A highly flexible multi-step treatment technology for chemical fixation and stabilization of leachable chromium, particularly hexavalent chrome, in contaminated soils, solid wastes, concrete, sludge, sand and gravel and waste waters is disclosed. The process comprises reducing hexavalent chromium to chromous (Cr.sup.2+) and chromic (Cr.sup.3+) forms in the presence of water under alkaline conditions and fixing the reduced chromium forms with phosphate.The process reduces Toxicity Characteristic Leaching Procedure chromium levels below the regulatory threshold of 5 mg/l as required by the USEPA.

Abstract: A re-calcination and extraction process for the detoxification and comprehensive utilization of chromic residues, comprising adding small amount of residue ore powder, sodium carbonate, or additionally, a certain amount of coke powder to the poisonous chromic residues, and calcining the mixture in a re-calcinating apparatus at 1000.degree.-1200.degree. C., for 30-60 minutes. The re-calcined grog is extracted with water, to obtain an extractive liquor containing sodium chromate. The extractive liquor can be used to produce chromium oxide, basic chromium sulfate or medium chrome yellow; while the extracted residues can be sintered at high temperatures with iron ore powder and coke to obtain a massive self-melting sintered iron, which can be further converted to a low-chromium cast iron. This process can thoroughly detoxify the chromic residues, effectively recover Cr2O3 and remove water-soluble Cr+6, whereby various important industrial materials are produced.

Abstract: Disclosed is an improvement on a process in which sodium chromate is reacted with sulfuric acid to produce sodium bichromate and sodium sulfate, and the sodium bichromate is reacted with sulfuric acid to produce chromic acid and sodium bisulfate. In the improvement, the sodium sulfate and sodium bisulfate are reacted with hydrogen chloride to produce sulfuric acid, which is recycled, and sodium chloride.

Abstract: Metallic iron particles are added to an aqueous solution containing hexavalent chromium and mechanically agitated. Enough of the surface of the iron particles remains precipitate-free to reduce substantially all the hexavalent chromium to trivalent chromium. Adjustment of pH allows the formation of insoluble precipitates which may be separated from solution using conventional techniques. The properties of the aqueous electrolyte solution are retained, and the solution may be reused.

Abstract: A method has been devised for removing chromium ions from a chromium ion containing liquid and recovering chromium oxide in a usable form by (a) adjusting the temperature of the liquid to an optimal temperature to maximize reduction and simultaneous precipitation of the chromium oxide; (b) adding a reducing agent to the liquid to form a mixture, where the reducing agent is at least one inorganic sulfur compound selected from the group of sulfur compounds where sulfur is in the 4.sup.+ oxidation state; and (c) adjusting the pH of the mixture to a pH between 5 and 7; (d) optionally further adjusting the pH of the mixture to a pH between above 7 to 12; and (e) separating the chromium from the mixture.

Abstract: In order to treat metal chlorides obtained in the form of dust collector solids in the production of titanium dioxide by the chloride process, the inert constituents, especially particulate coke, is separated then the metals are selectively precipitated and a maturing phase under oxidative conditions is provided for. The residue consisting of metal hydroxides is also not thixotropic in the absence of inerts. As a result, the material to be deposited has been cut in half.

Abstract: There is disclosed a method of treating a solution, e.g., an alkaline or acidic solution, containing heavy metals ions therein. With respect to alkaline solutions, the method includes providing a body of the solution; contacting the body with a material such as carbon dioxide to change the pH, e.g., to lower the pH to a pH in the range of 9 to 10.5; then treating the solution to further change the pH and cause precipitation of hydroxides, including chromium hydroxide; and separating the hydroxide precipitates from the solution to provide a substantially neutral solution having a reduced amount of chromium ions, for example, contained therein.

Abstract: An integrated process for the production of alkali or alkaline earth metal chlorates and chlorine dioxide in which the chromium compound impurities in the alkali or alkaline earth metal chlorate aqueous solution produced by an electrochemical cell are removed and recycled to the electrochemical cell; a substantially chromium compound free alkali or alkaline earth metal chlorate is converted to chlorine dioxide and by-products; and the by-products are converted to substantially chlorine-free carbon dioxide, which is vented, and a dilute solution of an alkali or alkaline earth metal chlorate, which is recycled to the electrochemical cell.

Abstract: For economical and assured separation of chromium, vanadium and titanium ions from acidic waste waters, which accrue in great quantities in preparation of titanium dioxide, the pH is first raised to around a value of 3 by addition of dolomite brick powder. Directly thereafter, the pH is fine tuned into the range of 4.3 to 4.7 through addition of calcium hydroxide and/or sodium hydroxide, and the hydroxides are separated with the aid of a flocculating agent. Since iron ions and calcium ions remain mainly dissolved in the waste water through such selective precipitation, only a relatively small volume of slush has to be disposed of.

Abstract: Chromium containing protein materials are treated by processes which include the steps of: combining the material to be treated with sufficient water to effect the solubilization of the gelable protein recovered therefrom, and an alkali additive. The mixture is thereafter held at a temperature of from about 60.degree. C. to about 85.degree. C. for a period of time of from about 0.5 hour to about 8 hours. The mixture is then filtered to remove the aqueous phase, which contains solubilized gelable protein. Subsequently, water is again added to the resultant chrome-containing proteinaceous cake and at least one enzyme is utilized to hydrolyze the remaining protein thus producing a product containing solubilized partially hydrolyzed protein and insoluble chromium. After separation, the chrome in the insoluble residue may be recycled into the pickling or tanning process, and the essentially chrome-free protein components may be used as ingredients in feeds, fertilizers, and cosmetics.

Abstract: A process of treating metal chloride wastes produced by chlorination of titanium ore comprises the steps of:(a) leaching said metal chloride wastes in a hydrochloric acid (HCl)-containing solution to obtain a solution containing solids and dissolved metals,(b) separating said dissolved metals from said solids present in the solution obtained in step (a) to obtain a liquid and a residue,(c) selectively precipitating the metals as their hydroxides by adding a neutralizing agent to the liquid obtained in step (b),(d) separating the precipitate of metal hydroxides obtained in step (c) from the liquid to obtain a residue, and(e) dewatering the residue obtained in step (d).

Abstract: The present invention provides a composition and process for the treatment of waste water containing chromium compound, for example water from a plating operation which includes significant concentration of a toxic chromium compound such as chromic acid. The chromium bearing solution is mixed with sufficient amount of hydrazine which can include selected minor concentrations of a cobalt salt to react with the chromium compound and render it insoluble. The chromium bearing water is introduced to a vessel which can have a baffle so that water introduced on one side of the baffle flows along a side of, then under the baffle and overflows on the other side. The hydrazine, which can include cobalt salt, is introduced to the incoming water at a rate to control the pH of the effluent from the vessel at a selected value of pH sufficient to remove all chromium from the effluent.

Abstract: A method has been devised for removing chromium ion from a chromium ion containing liquid and recovering chromium oxide in an usable form by (a) adjusting the temperature of the liquid to an optimal temperature to maximize reduction and simultaneous precipitation of the chromium oxide; (b) adding a reducing agent to the liquid to form a mixture, where the reducing agent is at least one inorganic sulfur compound selected from the group of sulfur compounds where sulfur is in the 4.sup.+ oxidation state and (c) adjusting the pH of the mixture to a pH between 5 and 7.

Abstract: The invention relates to a process for the production of sodium dichromate and sodium dichromate solutions by oxidative roasting of chrome ores under alkaline conditions, leaching of the furnace clinker obtained with water or an aqueous chromate-containing solution, adjustment of the pH to from 7 to 9.5, removal of the insoluble constituents by filtration, a sodium monochromate solution being obtained, conversion of the monochromate ions of this solution into dichromate ions by acidification and crystallization of sodium dichromate by concentration of this solution, characterized in that the acidification is carried out with carbon dioxide under pressure with removal of sodium hydrogen carbonate, the remaining solution is then very largely freed from sodium monochromate by cooling to a temperature below 10.degree. C.

Abstract: A process for removing molybdenum from uranium bearing solutions reduces molybdenum contamination of uranium product. The process employs solvent extraction techniques to remove molybdenum by using a molybdenum-selective extraction reagent of the chelating hydroxy-oxime type. The molybdenum-loaded extractant is stripped with dilute alkali for reuse. Where the uranium bearing solution originates from a solvent extraction process, a pretreatment stage is applied using an agent to remove entrained uranium extractant.

Abstract: Disclosed is a method of making hydrated chromic oxide of low sodium content by forming an aqueous solution of sodium bichromate, reducing the sodium bichromate to chromic oxide using sucrose or formaldehyde, which results in the precipitation of chromic oxide, filtering the hydrated chromic oxide, acid repulping and filtering or calcining the hydrated chromic oxide, followed by water repulp and filtering with displacement washing. The color of the particle can be controlled by the drying temperature. A composite particle of hydrated chromic oxide/carbon can be made by forming a slurry of the aqueous solution of sodium bichromate with powdered carbon. The composite particle can be heated to directly produce chrome metal.

Abstract: A process for precipitating and removing chromium compounds in which chromium is in the hexavalent state from aqueous liquids, particularly, alkaline earth metal or alkali metal chlorate-rich solutions containing chloride, chlorate, and bichromate ions produced by the electrolysis of brine. In the process, hydroxylamine, hydroxylamine sulfate, hydroxylamine formate or hydroxylamine hydrochloride is used as a reducing agent to react and co-precipitate at a neutral or acid pH with hexavalent chromium ions present in the aqueous liquid, the reaction and precipitation taking place, generally, at a pH of about 4.0 to about 6.5 and, a temperature of about 50.degree. C. to about 100.degree. C. Precipitated oxides and hydroxides of divalent and trivalent chromium can be removed, for instance, by filtration.

Abstract: A process for treating industrial waste water containing hexavalent chromium (Cr.sup.+6) and other heavy metals is disclosed which comprises reduction of Cr.sup.+6 to trivalent chromium (Cr.sup.+3) and the precipitation thereof with other heavy metals by addition of sulfide ion and ferrous ion to the waste stream at a pH of about 7 to 9 under conditions such that sludge production by the process of the invention is substantially less than that characteristic of prior art processes. Polymers are added to the solution to assist flocculation and clarification of the waste stream. More specifically, the invention comprises adding sulfide ion in a sulfide to hexavalent chromium ratio of about 0.7-2.5:1 and adding ferrous ion in a ferrous to hexavalent chromium ratio of about 0.5-5.0:1. The waste stream pH is preferably maintained in the range of about 7.2 to 7.5.