Abstract: A semiconductor device includes a contact via and a metal interconnect on the contact via. The metal interconnect has a portion extending in a lengthwise direction that is wrapped around and in contact with a sidewall of the contact via. Along a widthwise direction, the metal interconnect does not contact the sidewall of the contact via.

Abstract: Disclosed are a method of producing fine particulate alkali metal niobate in a liquid phase system, wherein the size and shape of particles of the fine particulate alkali metal niobate can be controlled; and fine particulate alkali metal niobate having a controlled shape and size. Specifically disclosed are a method of producing particulate sodium-potassium niobate represented by the formula (1): NaxK(1-x)NbO3 (1), the method including four specific steps, wherein a high-concentration alkaline solution containing Na+ ion and K+ ion is used as an alkaline solution; and particulate sodium-potassium niobate having a controlled shape and size.

Abstract: Disclosed are a method of producing fine particulate alkali metal niobate in a liquid phase system, wherein the size and shape of the particulate alkali metal niobate can be controlled; and fine particulate alkali metal niobate having a controlled shape and size. One of specifically disclosed is a method of producing a substantially rectangular cuboid particulate alkali metal niobate represented by MNbO3 (1), wherein M represents one element selected from alkaline metals, including specific four steps. Another one of specifically disclosed is particulate alkali metal niobate represented by the formula (1) having a substantially rectangular cuboid shape, wherein the substantially rectangular cuboid shape has a longest side and a shortest side, the length of the longest side represented by an index Lmax is 0.10 to 25 ?m, and the length of the shortest side represented by an index Lmin is 0.050 to 15 ?m.

Abstract: A process and system for recovering titanium dioxide and other value metals from a titanium bearing solid is disclosed. The process includes leaching the solid in hydrochloric acid to produce a leachate comprising undissolved solids and a leach solution comprising the titanium dioxide and the value metals, wherein the hydrochloric acid concentration is maintained above a value required to maintain the titanium dioxide and the value metals dissolved in the leach solution at atmospheric pressure. The leachate is separated into the leach solution and the undissolved solids. The concentration of hydrochloric acid concentration in the leach solution is reduced to recover titanium dioxide by hydrolysis and precipitation to produce a titanium dioxide rich slurry. In a preferred embodiment, HCl is recovered with a matrix solution.

Abstract: Vanadium oxide nanoparticles prepared by an inverse micelle hydrolysis of vanadium alkoxide in the presence of a basic catalyst.

Abstract: A mixture of Zinc Oxides or Hydroxides with Aluminum Hydroxides and Vanadium Oxide (V2O5) co-reacts in high temperature aqueous slurry to form highly crystalline forms of Hydrotalcite, containing the Decavanadate ion as a source of corrosion inhibition. The subject compositions, free of hexavalent chromium, are highly effective in providing blister-free corrosion prevention in typical coil and aerospace grade epoxy primer and color coat combinations.

Abstract: The present invention relates to a process for the conversion of cobalt(II)hydroxide into cobalt(III)oxidehydroxide (CoOOH) by reaction of the cobalt(II)hydroxide with oxygen in the presence of certain metal compounds. The invention further relates to the use of cobalt(III)oxidehydroxide thus prepared in the preparation of catalysts or catalysts precursors, especially catalysts or catalyst precursors for the conversion of synthesis gas into normally liquid and normally solid hydrocarbons and to normally liquid or solid hydrocarbons, optionally after additional hydrotreatment, obtained in such a conversion process.

Abstract: The invention relates to a method for preparing a lithium and vanadium oxide and the thus obtained products. The method comprises preparing a precursor gel by reacting hydrogen peroxide with ?-V2O5 in an aqueous medium in the presence of a lithium precursor and exposing the gel to a heat treatment in an oxidant atmosphere at a temperature ranging from 260° C. to 580° C. A compound of a formula Li1+xV3O8, (0.1<x<0.25) comprises needle-shaped grains having a bimodal distibution, wherein the length (L) of the first distribution needles ranges from 10 to 50 ?m and the length (L) of the second distribution needles ranges from 1 to 10 ?m.

Abstract: Methods and apparatus relate to catalysts and preparation of the catalysts, which are defined by sulfides of a transition metal, such as one of molybdenum, tungsten, and vanadium. Precursors for the catalysts include a metal ion source compound, such as molybdenum trioxide, and a sulfide ion source compound, such as thioacetamide. Once the precursors are dissolved if solid and combined in a mixture, homogenous precipitation from the mixture forms the catalysts. Exemplary uses of the catalysts include packing for a methanation reactor that converts carbon monoxide and hydrogen into methane.

Abstract: The present invention relates to a process for the removal of metal catalyst degradation products from a bleed stream of a catalytic chemical reaction process, wherein the catalyst is based on a metal selected from those in group VIII of the periodic table, chromium, copper, molybdenum, tungsten, rhenium, vanadium, titanium and zirconium, said process comprising treatment of the bleed stream with an alkali metal carbonate or ammonium carbonate source to form a solid complex or an aqueous solution of said solid complex, and removal of the solid complex or the aqueous solution of said solid complex from the bleed stream.

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: A chemical process that recovers the vanadium contained in inorganic acid solutions, precipitating it as a solid compound of vanadium and alkali metal or monovalent cation ferrocyanide, is disclosed. Separation is carried out electrochemically, depositing the compound onto a metal immersed in the acid solution that contains vanadium as well as other dissolved metals, to which a ferrocyanide salt of an alkali metal or a monovalent cation has been previously added. If the inorganic acid present in solution is different than nitric acid, the vanadium can also be separated by direct addition of a ferrocyanide salt of an alkali metal or a monovalent cation to the acid solution containing vanadium. The method described allows recovery of vanadium without modifying the initial composition of the solution, except for the concentration of the vanadium dissolved.

Abstract: An object of the present invention is to provide a method for purifying a highly pure niobium compound and/or tantalum compound, the method enabling the purification of a highly pure niobium compound and tantalum compound in a simplified manner at a low cost. The object is met by providing a method comprising adding an organic solvent to an aqueous solution containing a niobium compound and/or tantalum compound together with impurities, and then performing extraction via the solution. A niobium compound and/or tantalum compound dissolved in a solution is allowed to precipitate, and said aqueous solution is obtained by dissolving the precipitate in water.

Abstract: The present invention provides a method enabling the high purification of a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method enabling the high purification of a niobium compound and/or tantalum compound comprising the steps of preparing a solution containing niobium and/or tantalum, allowing a precipitate comprising niobium and/or tantalum to develop, separating the precipitate by filtration from the filtrate, converting the precipitate to a liquid melt or taking the filtrate, and separating a niobium compound from a tantalum compound or vice versa by utilizing the difference in solubility to the solvent between the niobium compound and the tantalum compound.

Abstract: Process wherein the vanadium present in the chromium ore chromite is recovered as vanadium pentoxide during the course of the fusion of the chromium ore with alkali and its work-up to produce sodium chromate solution and sodium dichromate.

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: Disclosed is a method for making amorphous spherical particles of zirconium titanate and crystalline spherical particles of zirconium titanate comprising the steps of mixing an aqueous solution of zirconium salt and an aqueous solution of titanium salt into a mixed solution having equal moles of zirconium and titanium and having a total salt concentration in the range from 0.01 M to about 0.5 M. A stearic dispersant and an organic solvent is added to the mixed salt solution, subjecting the zirconium salt and the titanium salt in the mixed solution to a coprecipitation reaction forming a solution containing amorphous spherical particles of zirconium titanate wherein the volume ratio of the organic solvent to aqueous part is in the range from 1 to 5. The solution of amorphous spherical particles is incubated in an oven at a temperature ?100° C. for a period of time ?24 hours converting the amorphous particles to fine or ultrafine crystalline spherical particles of zirconium titanate.

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: Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

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 process for preparing a reconstituted vanadyl sulphate/vanadous sulphate solution for use as an electrolyte in a vanadium redox battery is disclosed. The process includes preparing a starting material including a vanadyl sulphate/vanadous sulphate solution, evaporating the starting material by applying heat to form vanadyl sulphate/vanadous sulphate crystals, and re-dissolving the vanadyl sulphate/vanadous sulphate crystals with a volume of de-ionized water to form a reconstituted vanadyl sulphate/vanadous sulphate solution having substantially the same chemical composition at the starting material. A process for preparing a vanadyl sulphate/vanadous sulphate starting material from a vanadium bearing ore material, particularly a titaniferous magnetite ore material is also disclosed.

Abstract: There are disclosed amphoteric nano-sized metal oxide particles functionalized with silyl esters of a phosphonate and composites thereof with an acrylate-based monomer, including liquid crystal monomers photopolymerizable at ambient temperature. Also disclosed are the method making such functionalized particular by reacting a metal oxide with a silyl ester of a phosphonate in the presence of a non-aqueous solvent and in an inert atmosphere and the method of making the composites wherein the functionalized particles are admixed with an acrylate-based matrix monomer, including liquid crystal monomers photopolymerizable at ambient temperature. Further disclosed is the method of dental repair wherein the composites are applied to a tooth and photopolymerized.

Abstract: A process for recovery of vanadium dissolved in acid solution 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: A method of recovering metal and/or oxide thereof from a slurry is described. The method involves magnetically separating at least a portion of any magnetic impurities from the slurry and then leaching or dissolving at least a portion of any remaining magnetic impurities in a slurry. At least one chelating agent can then be added to the slurry and the solids can be recovered from the slurry by various separation techniques. The methods of the present invention are particularly useful in the recovery of tantalum and/or oxide thereof especially tantalum and/or oxide thereof having a very fine size.

Abstract: Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

Abstract: A process for recovering vanadium contained in inorganic acid solutions by precipitating the vanadium as a solid compound of vanadium and alkali metal or monovalent cation ferricyanide. Separation is carried out electrochemically by depositing the compound on to a metal immersed in the acid solution that contains vanadium, to which a ferricyanide salt of an alkali metal or a monovalent cation has been added. If the inorganic acid present in solution is different from nitric acid, the vanadium can be also separated by direct addition of a ferricyanide salt of an alkali metal or a monovalent cation to the acid solution containing vanadium. The method described allows recovery of vanadium without modifying the initial composition of the solution, except for the concentration of the vanadium dissolved.

Abstract: A process for the crystallization and re-establishment of a vanadyl/vanadous sulphate solution to its original chemical composition, and the use of a vanadium bearing ore material, in particular a titaniferous magnetite ore material, for producing the vanadyl/vanadous sulphate solution or crystals, particularly for use as an electrolyte in a vanadium redox battery.

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 process for the production of a vanadium compound from carbonaceous residues containing vanadium, which includes the steps of:

Abstract: A direct dissolution method for the purification of technical grade hydrated ammonium tantalum oxide (HATO), (NH4)2−xHxTa2O6.nH2O), and related compounds such as tantalum hydroxide and tantalum oxide is described. The method preferably uses ammonium bifluoride as fluoride source in place of the hydrofluoric acid used in the conventional methods. Other fluoride compounds such as NaF, KF, and CaF2 may be used.

Abstract: High yields of vanadium containing virtually no nickel or magnesium are obtained from natural bitumen ash consisting of up to 5% carbon, more than 95% of water-soluble compounds of vanadium, nickel and magnesium by mixing the ash with water to produce a 20% solids slurry of pH below 6.5 and temperature of 80-85° C. oxidizing any reduced vanadium in the slurry and then separating and removing the resulting polyvanadate precipitate from the liquid phase containing substantially all the nickel and magnesium values of the ash.

Abstract: Highly pure tantalum compounds are made by slurrying hydrated ammonium tantalum oxide or tantalum hydroxide with concentrated sulfuric acid followed by dissolution with concentrated hydrofluoric acid. After diluting the concentrated acidic solution with water, a soluble potassium compound is added to precipitate a highly pure potassium fluorotantalate. Further steps are used to convert the highly pure potassium fluorotantalate into a highly pure tantalum oxide.

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: A method is disclosed for the dissolution and purification of tantalum pentoxide. The impure tantalum pentoxide is reacted with a potassium-containing compound to form potassium tantalate. The potassium tantalate is optionally slurried with sulfuric acid and dissolved in an HF medium. The solution is suitable for purification by conventional ion exchange or solvent extraction methods. A potassium fluorotantalate precipitate may also be formed by adding KCl to the solution. The fluorotantalate precipitate may be further processed into a pure tantalum pentoxide by suspending the precipitate in an aqueous solution optionally containing a chelating agent and adding ammonium hydroxide to form ammonium tantalum oxide which can then be converted to tantalum pentoxide by calcining at high temperature.

Abstract: A process is disclosed for converting a spent catalyst from conventional fluorination processes into a commercially useful tantalum or niobium salt such as K.sub.2 TaF.sub.7 or K.sub.2 NbF.sub.7. The process broadly relates to dissolving the spent catalyst in water or an aqueous hydrofluoric acid solution, separating and disposing the undissolved residue, extracting the aqueous solution with a suitable solvent such as methyl isobutyl ketone (MIBK), and obtaining useful tantalum products from the MIBK solution such as a tantalum salt.

Abstract: A process for treatment of hazardous liquid waste comprising trace amounts of hazardous elements in solution as oxyanions by oxyanion fixation within ettringite and related minerals. In accordance with the disclosed process, reagents for forming ettringites are mixed with the waste stream resulting in the formation of oxyanion-substituted ettringite and related materials. The resulting ettringite and related minerals are separated by filtration from the liquid. Thereafter, the liquid, having an elevated pH, is neutralized by carbon dioxide sparging resulting in precipitation of excess reagents in the liquid. Thereafter, the precipitates are filtered, producing a clean liquid.

Abstract: A process for removal of thorium from titanium chlorinator waste comprising: (a) leaching an anhydrous titanium chlorinator waste in water or dilute hydrochloric acid solution and filtering to separate insoluble minerals and coke fractions from soluble metal chlorides; (b) beneficiating the insoluble fractions from step (a) on shaking tables to recover recyclable or otherwise useful TiO.sub.2 minerals and coke; and (c) treating filtrate from step (a) with reagents to precipitate and remove thorium by filtration along with acid metals of Ti, Zr, Nb, and Ta by the addition of the filtrate (a), a base and a precipitant to a boiling slurry of reaction products (d); treating filtrate from step (c) with reagents to precipitate and recover an iron vanadate product by the addition of the filtrate (c), a base and an oxidizing agent to a boiling slurry of reaction products; and (e) treating filtrate from step (d) to remove any remaining cations except Na by addition of Na.sub.2 CO.sub.3 and boiling.

Abstract: A process for the preparation of ceramic material Lithium stannate doped with a transition metal for a humidity sensor mixes a salt of Lithium with SnO.sub.2 in dry condition, thereafter mixes in wet conditions using an organic solvent, adds a transition metal compound to the resulting mixture, mixes the mixture thoroughly, drys and compacts the mixture in the range of 5000 to 8000 lbs and heats the pellets so formed at a temperature in the range of 600.degree. to 800.degree. C. for a period in the range of 6 to 12 hours followed by slow cooling to room temperature.

Abstract: A process for recovering metal and acid values from a source material containing metallic fluorides comprises digesting the source material in sulfuric acid to form a slurry, separating a fluoride containing solid phase and a metal containing first liquid phase. The solid phase is subjected to pyrohydrolysis, sulfuric and hydrofluoric acids are recovered, and the first liquid phase is processed to recover the metal values by solvent extraction or ion exchanges. The tantalum values are extracted from the first liquid aqueous phase by a water immiscible organic extractant such as methylisobutyl ketone to form a first liquid organic phase containing tantalum and a second liquid aqueous phase. The tantalum is stripped from the first organic phase using water. The process includes the additional steps of heating the separated solid phase from about ambient temperature to an elevated temperature in the presence of water vapor to evolve sulfuric acid and render the gangue chemically inert.

Abstract: A material for a magnetic head slider consists essentially of 0.1 to 20.0 vol % of at least one of oxides the group Va elements of the International Periodic Table (Ta, Nb, V) and 80.0 to 99.9 vol % of stabilized cubic ZrO.sub.2 containing a stabilizer (Y.sub.2 O.sub.3, MgO, CeO.sub.2). It has improved precision machinability, machining efficiency, high strength, densified structure, affinity with the recording medium or lubricity, besides wear resistance. It may be machined precisely into a thin film magnetic head slider with a reduced amount of chipping.

Abstract: A process for the preparation of a vanadium oxide colloidal dispersion is provided. The process includes a step of hydrolyzing vanadium oxoalkoxide with an excess of water to form a vanadium oxide colloidal dispersion containing at least a minimum effective amount of vanadium and no greater than about 3.5 wt-% vanadium, preferably containing about 0.3 wt-% to about 2 wt-% vanadium. The process can be carried out in the presence of an organic polymer or prepolymer to form a polymeric vanadium oxide colloidal dispersion.

Abstract: The process for recovering Ta/Nb values from highly flourinated ore materials by the process of;(a) contacting the materials with one or a mixture of HNO.sub.3 or HCl, and H.sub.3 BO.sub.3 wherein the H.sub.3 BO.sub.3 to other acid molar ratio is from about 1/10 to about 1/1,(b) maintaining the temperature between about 55 C. and about 85 C.,(c) reacting for a sufficient period to substantially solubilize the major portion of the materials and to substantially insolubilize all Ta/Nb values, and(d) separating the solids containing the Ta/Nb values from solution.

Abstract: A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Abstract: Fine particles of vanadium oxide or compound thereof, respectively represented by the general formulas V.sub.2 O.sub.5 and LiV.sub.3 O.sub.8, are prepared by freeze-drying a wet mixture containing a precursor. Alternatively, such oxide or compound is prepared in fine particle form intimately mixed with fine particles of carbon, also by freeze-drying.

Abstract: Disclosed is a method of removing soluble vanadium from an aqueous stream containing sodium chromate or sodium bichromate. The liquor is passed over a water-insoluble trivalent chromium compound, and the vanadium in the liquor is extracted from the liquor onto the trivalent chromium compound. The process is especially useful in removing vanadium from a recycled concentrated sodium bichromate liquor to prevent the buildup of vanadium therein.

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: An apparatus for removing vanadium from phosphoric acid includes a precipitator that receives vanadium-containing process-feed phosphoric acid and adds an oxidant to the process-feed phosphoric acid, whereupon precipitates containing phosphorus and vanadium are formed in a phosphoric acid filter feed slurry. The solid precipitate is removed by a filter. The filtrate, after optional further oxidation, is contacted to an ion exchange resin to remove additional vanadium from the filtrate to produce a phosphoric acid product of reduced vanadium content. A first portion of the phosphoric acid product is removed from the apparatus for further use. A reducing agent is added to a second portion of the phosphoric acid product, and the reduced acid is used to strip vanadium from the loaded ion exchange resin. The vanadium-loaded second portion of the phosphoric acid is mixed with fresh phosphoric acid and fed to the precipitator.

Abstract: Improved solvent extraction recovery of tantalum and niobium oxides from an acid solution of raw materials containing such oxides wherein the charged organic solvent [e.g., MIBK] is washed out (a) with 8-16N sulfuric acid and then (b) with water or dilute HF. This avoids the use of a second mineral acid addition after digestion by HF of raw materials (and avoids problems attendant to use a second mineral acid).

Abstract: Fluorine content of tantalum and niobium hydroxides is reduced to under 0.5 weight % by washing such hydroxide precipitates (as obtained by HF digestion and solvent extraction) with dilute ammonia (1 to 10%) and then water in two washing stages. The first washing stage includes a partial neutralization and the used wash water of the second stage is advantageously recycled, after adjustment of its ammonia concentration, for use as the first stage washing liquid.

Abstract: A method of removing niobium from a uranium-niobium alloy includes dissolving the uranium-niobium alloy metal pieces in a first aqueous solution containing an acid selected from a group consisting of HCl and H.sub.2 SO.sub.4 and a fluoboric acid as a catalyst to provide a second aqueous solution which includes uranium (U.sup.+4), acid radical ions, the acids and insolubles including uranium oxides and niobium oxides; adding nitric acid to the insolubles to complete the oxidation of the niobium oxides to yield niobic acid and further solubilizing thr uranium oxide; and separating the niobic acid, nitric acid and solubilized uranium oxides.