Abstract: A method for recovering chromite from ore slurry obtained by processing nickel oxide ore, the raw material, in a plant for the wet smelting of nickel oxide ore. In the method chromite is separated and recovered from an ore slurry obtained from a nickel oxide ore when nickel and cobalt are recovered from the nickel oxide ore. The method has a grain diameter separation step for separating the ore slurry on the basis of a predetermined classification point according to the difference in the grain diameter of particles contained in the supplied ore slurry and a sedimentation separation step for causing the oversized ore slurry separated in the grain diameter separation step to undergo sedimentation and concentration on the basis of a target classification point, and recovering the chromite. The coarse particle content of the oversized ore slurry separated in the grain diameter separation step is adjusted to 30-50%.

Abstract: A metal recovery process for heavy effluent from a hydroconversion process. The effluent contains unconverted residue and a solid carbonaceous material containing group 8-10 metal, group 6 metal, and vanadium and/or nickel, and the metals are recovered according to the invention.

Abstract: A method of treating metal-contaminated spent foundry sand, or other industrial waste, by combining the sand with a sulfite to produce insoluble metal sulfur oxide complexes that do not leach from the sand. The treated waste may also be processed to reducing “clumping,” thereby rendering the treated waste appropriate for use in another industrial process.

Abstract: A method of treating metal-contaminated spent foundry sand, or other industrial waste, by combining the sand with a sulfite to produce insoluble metal sulfur oxide complexes that do not leach from the sand. The treated waste may also be processed to reduce “clumping,” thereby rendering the treated waste appropriate for use in another industrial process.

Abstract: Stable suspensions of coated magnetic particles, preferably resuspendable bioactive particles particularly useful in Magnetic Resonance Imaging, are produced by disrupting, what are presumed to be, crystalline agglomerates of a parent particulate magnetic starting material in the presence of a coating material, such that coating can take place during the disruption. The particles are generally coated in suspension yielding a stable suspension of subdivided particles. With the proper selection of a coating material, preferably a protein or other biochemically or biologically active polymer such as an antibody, a resuspendable (colloidal) bioactive product is obtained.

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 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: 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: The present invention is directed to a method for treating a sludge containing substantial amounts of chromium, aluminum, calcium, iron, and phosphorous. The method comprises forming a slurry of the sludge; reacting the slurry with an acid to dissolve substantially all the aluminum and chromium and provide a solids residue comprising mostly calcium sulfate; separating the chromium/aluminum-containing solution from the solids residue; raising the pH of the chromium/aluminum solution to precipitate chromium as chromium hydroxide; and separating the chromium hydroxide from the remaining aluminum-containing solution. The chromium hydroxide is then enriched with an alkali or earth alkali compound and calcined in an oxidizing atmosphere to convert the chromium to a chromate. The calcine is leached in an aqueous medium at a controlled pH to yield a high concentration, high purity chromate solution suitable for producing metallic chromium or a variety of chromium chemicals.

Abstract: Disclosed is a method of making chromic acid by electrolyzing an aqueous solution of sodium bichromate until the sodium bichromate is converted to chromic acid at a bichromate percent conversion of about 1 to about 48.4. Sulfuric Acid is then added to the aqueous solution in an amount between stoichiometric and about 30 wt % in excess of stoichiometric to convert the remaining sodium bichromate to chromic acid. This results in the precipitation of chromic acid, which is separated from the aqueous solution.

Abstract: A process for the production of sodium dichromate comprising reacting sodium chromate with acids, the acids being sulfuric acid and NaHSO.sub.4 formed as a waste product in the production of CrO.sub.3 and thus being contaminated with chromium compounds, adding PO.sub.4 ions in excess to the NaHSO.sub.4 contaminated with chromium compounds and precipitating the Cr(III) present therein as CrPO.sub.4 at a temperature of 50.degree. to 100.degree. C. and at a pH value of 3 to 6.

Abstract: A method for recovering chromium from chromium-bearing material which comprises heating the material which can contain any one or combination of Co, Ni, Fe, Mo, and W with solid alkali metal hydroxide in an oxidizing atmosphere at 600.degree. C.-1000.degree. C. to form a fused material containing water soluble compounds of Cr, Mo, and W contained therein. The fused material is cooled and contacted with water to form a leach solution and a residue. The leach solution is adjusted to a pH of from about 5-8 with sulfuric acid, and a water soluble calcium salt is added. The chromium-rich liquor is then adjusted to a pH of 1-3 with sulfuric acid. Sodium metabisulfite is added to the chromium-rich liquor to reduce the chromium to the trivalent state after which the pH is adjusted to 5-8 with a base to form a precipitate of essentially all of the chromium.

Abstract: Methods are disclosed for recovering one or more of the metals of tungsten and molybdenum from metal-cellulose material. One method involves digesting the material in a mineral acid selected from the group consisting of hydrochloric acid having a concentration of at least about 4 normal, and sulfuric acid having a concentration of at least about 9 normal at a temperature of at least about 50.degree. C. for a sufficient time to form a digestion solid containing the major portion of the tungsten and a digestion solution containing a portion of any molybdenum which is present in the material, and separating the solid from the solution. Another method involves having as the starting material a metal-cellulose material comprising one or more of the metals of tungsten and molybdenum and elements selected from the group consisting of arsenic, phosphorus, silicon, and combinations thereof.

Abstract: Aqueous effluent solutions containing metal cations may be treated with an extractant comprising an organophosphinic acid, a di-2-ethylhexyl phosphoric acid and/or an aliphatic amine to selectively separate chromium, nickel, cobalt, copper and lead cations from the aqueous solution. Typical extraction techniques include liquid-liquid extraction employing either mixer settlers or columns, liquid membrane extraction and selective supported membrane extraction.

Abstract: A method of extracting tungsten values from tungsten containing ores comprising step (i) forming a mixture of a tungsten containing ore and a first mineral acid adapted to consume acid consuming substances in the ore and step (ii) thereafter adding organic anions to produce a solution containing dissolved tungsten values.

Abstract: A method of processing manganese ore by adding the ore to an aqueous solution of acid and H.sub.2 O.sub.2 to form a leach pulp. The leach pulp is agitated for a predetermined time period at predetermined temperatures. The leach pulp is then separated into a solid fraction and a liquid fraction containing solubilized metals. The solubilized metals are then recovered from the liquid fraction.

Abstract: A process is disclosed for recovering tungsten from tungsten bearing material containing arsenic. The process involves adjusting a water slurry of the material to a pH of less than about 4 with an acid to solubilize the major portion of the tungsten, adding an insoluble ferric compound to the slurry to form a two phase system in which the solid phase contains the major portion of the arsenic and of any phosphorus which may be present, and a solution phase containing the major portion of the tungsten. After separation of the solid from the solution, the solution is adjusted to a pH of less than about 2 with an acid and a suffficient amount of hexamethylenetetramine is added to the solution to precipitate the major portion of the tungsten, followed by separating the precipitate from the resulting liquor. The solid phase containing the arsenic and phosphorus, if any, can be contacted with water and a soluble ferric salt to produce a treated solid which passes the EP toxicity test.

Abstract: In accordance with the present invention, the chromium content of an aqueous waste containing significant amounts of at least one soluble chromium compound, such as blowdown waters from cooling towers utilizing chromium-containing materials as corrosion inhibitors is reduced, by contacting the chromium-containing waste water with an aqueous waste containing sodium sulfides, particularly spent caustic utilized in a desulfurization of petroleum fractions, to precipitate a substantial amount of the chromium and, thereafter, separating the precipitated chromium from the mixture as a sludge, to produce a waste water which can be safely disposed of to the earth's surface in a sewer or the like.

Abstract: A process is disclosed for recovering chromium from a chromium bearing material containing cobalt, molybdenum, and tungsten. The process involves roasting the material and alkali metal compound at a temperature of at least about 400.degree. C. for a sufficient time to react the alkali metal compound with the material and form a reacted mixture containing essentially all of the chromium, molybdenum, and tungsten as alkali salts. The reacted mixture is water leached to dissolve the alkali salts and form a leach solution containing essentially all of the chromium, molybdenum, and tungsten, and a leach solid containing essentially all of the cobalt. After separation of the leach solution from the leach solid, the pH of the leach solution is adjusted to from about 0.5 to about 3.0 with an acid and a sufficient amount of a reducing agent is added to reduce essentially all of the chromium to the trivalent state.

Abstract: A process for the recovery of aluminum and at least one other metal selected from the group consisting of molybdenum, nickel and cobalt from a spent hydrogenation catalyst comprising (1) adding about 1 to 3 parts H.sub.2 SO.sub.4 to each part of spent catalyst in a reaction zone of about 20.degree. to 200.degree. C. under sulfide gas pressure between about 1 and about 35 atmospheres, (2) separating the resultant Al.sub.2 (SO.sub.4).sub.3 solution from the sulfide precipitate in the mixture, (3) oxidizing the remaining sulfide precipitate as an aqueous slurry at about 20.degree. to 200.degree. C. in an oxygen-containing atmosphere at a pressure between about 1 and about 35 atmospheres, (4) separating the slurry to obtain solid molybdic acid and a sulfate liquor containing said at least one metal, and (5) recovering said at least one metal from the sulfate liquor in marketable form.

Abstract: A process is disclosed for recovering tungsten, iron, and manganese from tungsten bearing material. The process involves digesting the material in a sulfur dioxide solution at a sufficient temperature for a sufficient time to form a digestion solution containing the major portion of the scandium, iron, and manganese, and a digestion solid containing the major portion of the tungsten which is separated from the digestion solution. The major portion of the scandium is extracted from the digestion solution with an organic consisting essentially of an extracting agent which is essentially a mixture of alkyl primary amines which are present in an amount sufficient to extract the major portion of the scandium without extracting appreciable amounts of iron and manganese, and the balance an essentially aromatic solvent. After separation of the scandium containing organic from the raffinate, the organic is stripped of the scandium with hydrochloric acid which is then separated from the stripped organic.

Abstract: A process is disclosed for recovering tungsten, scandium, iron, and manganese from tungsten bearing material. The process involves digesting the material in sufficient sulfuric acid at a sufficient temperature for a sufficient time in the presence of a reducing agent to form a digestion solution containing the major portion of the scandium, iron, and manganese, and a digestion residue containing the major portion of the tungsten, separating the digestion solution from the digestion residue and extracting essentially all of the scandium from the solution with an organic consisting essentially of an extracting agent which is a dialkyl phosphoric acid which is present in an amount sufficient to extract essentially all of the scandium without extracting appreciable amounts of iron and manganese, and the balance an essentially aromatic solvent.

Abstract: A process for enhancing recovery of metals, especially cobalt, from spent hydroprocessing catalysts when the spent catalyst particles are first roasted at between 400.degree. C. and 600.degree. C. and then contacted with a first aqueous solution of ammonia and an ammonium salt to recover nickel, cobalt, molybdenum, tungsten, and vanadium. The once-leached spent hydroprocessing catalysts are again leached by contacting them with a second aqueous solution of ammonium sulfate at a pH of 1 to 4.

Abstract: The Abstract of the Invention is a method of making a solution of the nitrates of iron and chromium from a spent catalyst containing oxides of iron and chromium, which method comprises:(a) dissolving the catalyst in sulphuric acid;(b) reacting the resulting sulphates solution with a source of nitrate ions and of cations of which the sulphate is of low solubility, whereby to precipitate such sulphate;(c) separating the sulphate, whereby to give a nitrates solution of low sulphate content.

Abstract: A method of recovering chromium values and potential energy from liquid and solid leather tannery wastes comprising pyrolyzing the tannery wastes to produce a burnable fuel product comprising gases and liquids and a substantially solid chromium-containing residue, recovering chromium compounds from the solid residue and using the fuel to supply energy for the system.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt, nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup..dbd., VO.sub.4.sup..tbd., WO.sub.4.sup..dbd., and CrO.sub.4.sup..dbd. and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

Abstract: Molybdenum or other heavy metal anions and ferric sulfate are reclaimed from wastewater skimmings, that result from treatment of wastewaters through formation of insoluble heavy metal ferric salts and flotation, by treating the skimmings with aqueous caustic at 150.degree.-225.degree. F. to form a solution of the heavy metal anions and a residual solids fraction, separating the solids and contacting the residual solids with sulfuric acid to produce ferric sulfate.

Abstract: A method for treating nonferrous metal hydroxide sludge waste to separate and recover the nonferrous metals therein wherein the waste is first mixed with an alkali hydroxide or carbonate, dried, and then roasted and the water-insoluble residue in the roasted material is treated with sulfuric acid to produce an acid-insoluble residue and a sulfuric acid solution containing copper, aluminum and chromium and thereafter, separating the copper from this solution by liquid-liquid extraction and thereafter, separating the aluminium, chromium, zinc and nickel from the remaining solution by separate liquid-liquid extraction steps.

Abstract: The invention is a method for working-up shale while recovering metals therefrom and the sulphur content thereof. The method comprises crushing the shale and leaching and roasting the shale. The sulphur content is oxidized and converted into sulphuric acid, concentrated sulphur dioxide or sulphur. The leaching operation is effected with sulphuric acid. The leached metals are recovered in a manner known per se and the residual solution is passed to the roasting stage.

Abstract: A process and a product formed thereby for the recovery of chromium values from aqueous solutions (e.g., waste liquors) comprises contacting an acidic solution containing sulfate ion and trivalent chromium ion with at least about 4 molar equivalents of MgO or Mg(OH).sub.2 per 3 molar equivalents of trivalent chromium in addition to the amount required to neutralize the free acid to a pH of about 4 to form an amorphous, dense solid, grainy, easily settleable, trivalent chromium-containing precipitate in an alkaline solution according to the equation: 3Cr.sub.2 (SO.sub.4) + 8 MgO .fwdarw.Cr.sub.2 (OH).sub.4 SO.sub.4 .multidot. 4Cr(OH).sub.3 .multidot. 4H.sub.2 O + 8 MgSO.sub.4. The trivalent chromium-containing product can be readily separated from the water and is a useful source of chromium for subsequent processing. The water remaining after separation of the precipitate contains less than 0.5 mg/l chromium.

Abstract: Chromium values may be recovered from the chromium bearing ores or sources by subjecting the chromium bearing source to a roast in the presence of sulfuric acid and an oxidant which contains manganese compounds at temperatures ranging from about 200.degree. to about 500.degree. C. followed by leaching, separation and solvent or ion exchange extraction whereby chromium is selectively extracted and recovered.

Abstract: Manganese values may be recovered from manganese bearing sources by subjecting said source to a roast in the presence of sulfuric acid and a reductant which comprises a chromium-containing compound at temperatures ranging from about 200.degree. to about 500.degree. C. followed by leaching, separation, solvent extraction or ion exchange whereby manganese is extracted, followed by separation and recovery of the manganese.

Abstract: An improved hydrometallurgical method is provided for producing technical grade molybdic oxide from molybdenite concentrates. According to this method, the molybdenite concentrates are leached in an acid medium having a nitric acid concentration between about 25 gpl and about 50 gpl and an initial sulphuric acid concentration of nil to about 750 gpl, under oxygen pressure of about 100 - 250 psig and at a temperature above 115.degree. C so as to produce technical grade molybdic oxide having not more than 0.1% sulphur. Then a liquid-solid separation of the reaction mixture is effected and the obtained leach liquor is recycled back to the leaching stage optionally after partial neutralization with a basic reagent. The solid is washed and recovered as technical grade molybdic oxide.This invention relates to a novel method of producing hydrometallurgically technical grade molybdic oxide from molybdenite concentrates.

Abstract: Naphthenohydroxamic acid is prepared by reaction at 25.degree.C to 30.degree.C, equimolar quantities ofA. an ester of naphthenic acid,B. hydroxylamine dissolved in an alcohol/water/alkali metal sulfate slurry wherein the water content of the slurry is insufficient to hydrolyze the ester during conversion to naphthenohydroxamic acid, andC. an alkali metal hydroxide dissolved in alcohol.Naphthenohydroxamic acid is useful as a chelating agent in hydrometallurgy to recover metal values from dilute solution.

Abstract: Processes for preparing vanadium- and chlorine-free sodium bichromate which comprises concentration of a sodium chromate liquor so as to cause formation of crystals of neutral sodium chromate tetrahydrate, separation of these crystals from their mother liquor, treatment thereof with sulfuric acid, concentration of the acid solution obtained, and after separation of insoluble sodium sulfate so formed, crystallization of sodium bichromate.

Abstract: A method for purifying technical grade molybdenum oxide derived from the roasting of molybdenite concentrates by which the molybdenum oxide feed material is admixed with sulfuric acid and pugged to form a plurality of reaction pellets which are heated to an elevated temperature to effect a baking and subsequent roasting thereof and a reaction between the metal contaminants and the sulfuric acid to produce aqueous soluble sulfate compounds. The resultant roasted pelletized oxide is ground and leached to remove the contaminating metal sulfates, whereafter the leached pellets are contacted with an aqueous ammoniacal solution for converting the molybdenum oxide constituent therein to ammonium molybdate dissolved in the solution, which is separated from the insoluble residue, which is discarded to waste and the solution is crystallized to recover the ammonium molybdate product which, in turn, may be calcined to produce a high purity molybdenum oxide product.