Abstract: A method for producing alkali metal chromates by double roasting chrome ores without the use of alkaline earths is disclosed. The pollution and hygiene problems associated with the use of lime are substantially eliminated and only negligible amounts of alumina are found in the product chromate liquors without employing steps previously thought necessary. These advantages are achieved by controlling (1) the Bichromate Equivalent: aluminum oxide ratio in the mix, (2) the amount of alkali metal salts added to the mix, (3) the roasting time, (4) the composition and alkalinity of the liquor used for leaching the roast, and (5) the temperature employed, in both roasts.

Abstract: From roasted products of used catalysts from hydrotreatment desulfurization of petroleum, valuable molybdenum, vanadium, cobalt and nickel are recovered easily and a high percent recovery by means of a combination of simple chemical procedures and also inexpensive chemicals. The recovered metal components can be reused for preparing new catalysts and the like.

Abstract: In the recovery of chromium from a residue containing chromate and vanadate, by oxidative decomposition of a chromium and vanadium-containing ore in the presence of an alkali at temperatures of about 600 to 1200.degree. C., and leaching such residue with water, the improvement which comprises adding titanium dioxide to the residue and heating, whereby upon leaching the chromium enters the water while the vanadium is substantially left in the residue.

Abstract: A novel group of corrosion inhibiting pigments has been discovered, which is based on zinc molybdate compounds selected from sodium zinc molybdate, potassium zinc molybdate, ammonium zinc molybdate and mixtures thereof, combined with a suitable carrier, so that the proportion of the zinc molybdate compound is such that the Mo content in the pigment is between about 1 and 30% by weight. Such pigments can be prepared in situ by several methods, such as a double decomposition reaction of sodium, potassium or ammonium molybdate and a solution containing dissolved zinc ion, or an addition of an appropriate acid to zinc oxide dispersed in sodium, potassium or ammonium molybdate solution, or an addition of zinc oxide to a solution which comprises molybdic oxide dissolved in an aqueous solution of sodium, potassium or ammonium molybdate.

Abstract: In the disintegration of at least one chromium source selected from the group consisting of a SiO.sub.2 -containing chromite and a chromium-containing residue with an alkali compound at a temperature above about 800.degree. C in the presence of atmospheric oxygen and a lime-free diluent, followed by leaching of the mixture with at least one of water and/or a chromium (VI)-containing aqueous solution, the improvement which comprises including in the mixture to be disintegrated an aluminum compound and at least sufficient alkali to form alkali chromate and to convert the SiO.sub.2 into an alkali-aluminum silicate corresponding to the formula nMe.sub.2 O . mSiO.sub.2 . Al.sub.2 O.sub.3, wherein Me is at least one of sodium and potassium, 0.8 .ltoreq. n .ltoreq. 1.2 and 1.3 .ltoreq. m .ltoreq. 4.3.

Abstract: Vanadium and molybdenum are recovered from a spent desulfurization catalyst containing the same by a process involving intimately admixing with comminuted catalyst an amount of a solid alkali metal carbonate, such as calcined sodium carbonate, sufficient to convert the vanadium and molybdenum present into water-soluble compounds, heating the mixture in the solid state in the presence of air at a temperature between about 650.degree. C and about 850.degree. C for a period of about 1 to 2 hours, and extracting the vanadium and molybdenum compounds with water.

Abstract: A process is provided for extracting tungsten values from tungsten compositions. The process comprises treating a tri (alkaline earth metal) tungstate, especially tricalcium tungstate, at a temperature of preferably no greater than 50.degree. C. with a aqueous solution of hydrochloric and/or nitric acid, preferably having a concentration of no greater than 5 molar. The acid is supplied in excess of te stoichiometric amount required to convert the tungstate to tungstic acid and sufficient to maintain the thusly formed tungstic acid insoluble in the solution. The tungstic acid can then be separated from the solution and converted to soluble ammonium tungstate, which in turn can be converted into tungsten trioxide and finally into metallic tungsten. The tri (alkaline earth metal) tungstate starting material can be prepared from iron tungstate, manganese tungstate, and/or an alkaline earth metal tungstate or from ores or concentrates of these tungstates, by a high temperature treatment with calcium oxide.

Abstract: A process is provided for the manufacture of a tungstate salt, especially ammonium tungstate. The process comprises treating finely divided metallic tungsten and/or intermetallic iron/tungsten species with an aqueous solution in the presence of an oxidizing agent, such as oxygen or hydrogen peroxide. The solution contains cations which are ammonium and/or alkali-metal ions and anions which are hydroxide, carbonate and/or bicarbonate ions. The finely divided material generally contains no more than impurity quantities of alkaline earth metals. The process is useful in deriving tungsten values from wolframite ores, which are reduced prior to the aqueous treatment.

Abstract: A process is provided for treating tri (alkaline earth metals) tungstates with an aqueous solution containing cations selected from ammonium, sodium and potassium ions and mixtures thereof, and anions selected from hydroxide, carbonate, bicarbonate, and phosphate ions and mixtures thereof, to form a tungstate salt which is soluble in the solution and an alkaline earth metal compound which is insoluble in the solution. The tri (alkaline earth metal) tungstate can be prepared from iron tungstate, manganese tungstate, and/or an alkaline earth metal tungstate or from ores or concentrates of these tungstates, by a high temperature treatment with an alkaline earth metal donor compound, such as calcium oxide. A preferred soluble tungstate is ammonium tungstate, which can be further processed to yield tungsten trioxide and/or tungsten.

Abstract: A process is provided for preparing ammonium tungstate. In the process, a reduced calcium tungstate is treated in the presence of an oxidizing agent with an aqueous solution having at least ammonium cations and carbonate and/or bicarbonate anions, at a temperature of 10.degree. C to the boiling point of the solution. The reduced calcium tungstate reacts with the ammonium cations to form the ammonium tungstate which is soluble in the solution and with the anions to form a calcium compound which is insoluble in the solution. Oxygen and/or hydrogen peroxide are preferred oxidizing agents. The process is especially useful in separating tungsten values from scheelite ores or concentrates.

Abstract: A process of recovering molybdenum in the form of molybdic acid from waste products and particularly from spent catalysts containing a support based on gamma-alumina wherein the molybdenum is in the form of molybdenum oxide or molybdenum sulfide comprising treating the waste products with sodium carbonate and heating to convert the molybdenum present to sodium molybdate, and converting the sodium molybdate to molybdic acid by treatment with concentrated nitric acid to produce molybdic acid high in purity that is suitable for the production of molybdenum compounds as well as for the recovery of the pure metal.

Abstract: A process of recovering molybdenum from waste products and particularly from spent catalyst based on active alumina and containing molybdenum compounds comprising mixing the spent catalyst with sodium carbonate powder, adding water and remixing to absorb the water in the catalyst particles, baking the mixture to convert the molybdenum present to sodium molybdate, treating the mixture at ambient temperature with carbon dioxide gas, treating the resultant mixture with hot water to dissolve the sodium molybdate, neutralizing and clarifying with concentrated nitric acid, and precipitating to produce molybdic acid high in purity that is suitable for the production of molybdenum compounds as well as for the recovery of the pure metal.

Abstract: A method of treating raw materials containing components of metals of the group IVb of the Periodic Table, which comprises heat-treating a raw material of a component of a metal of the group IVb of the Periodic Table containing coloring poisonous metal components such as Mn, V and Cr components in the presence of a flux composed mainly of an alkali metal nitrate or an alkali metal peroxide which is a thermal decomposition product of the alkali metal nitrate in an amount 2 to 5 times the amount of the raw material on the weight basis in a non-reducing atmosphere to thereby effect fluxing reaction, and subjecting the resulting fluxing reaction product to a leaching treatment of at least one stage in an aqueous medium to separate the fluxing reaction product into said coloring metal components and a concentrate of the component of the group IVb of the Periodic Table which is acid-soluble and substantially free of said coloring poisonous metal components.

Abstract: In the alkaline-oxidative disintegration of chromites into chromates with an alkali comprising reacting a chromium ore in the presence of oxygen and a diluent, and leaching the reaction mixture with at least one of water and/or a chromate-containing aqueous solution, the improvement which comprises reacting the residue obtained after leaching with an excess of alkali, based on the chromium oxide content of the residue, in the presence of oxygen, grinding the reaction mixture and, without leaching, employing the ground reaction mixture as an alkali source in another chromite disintegration cycle. The alkali reacted with the leaching residue is preferably sodium and/or potassium hydroxide and/or carbonate and is employed in about 100 to 400%, and preferably about 150 to 330%, of the stoichiometric amount based on the chromium oxide content of the leaching residue.

Abstract: A process for purifying an impure molybdenum oxide concentrate feed material to remove therefrom the predominant portion of contaminating metals present by autoclaving at an elevated temperature under an oxygen partial pressure of at least about 100 psi, a slurry of the particulated feed material in an aqueous acid solution containing a mineral acid for a period of time sufficient to convert the predominant portion of molybdenum compounds to molybdenum trioxide and to convert the contaminating metal compounds present to aqueous acid soluble compounds. The autoclaved slurry is thereafter filtered and the solids are subjected to an aqueous alkali hydroxide leach treatment to extract the molybdenum trioxide constituent therein in the form of alkali metal molybdate compounds, which subsequently are recovered from the leach liquor in the form of a high purity alkali metal molybdate product.

Abstract: In the recovery of molybdenum and rhenium values from sulfide ores, silica impurity is reduced to low levels by adding alumina to a carbonate fusion mix in an amount sufficient to combine with the silica present to form insoluble aluminum silicates, thus preventing its removal from the fusion mass during removal of soluble molybdenum and rhenium values by leaching, and thereby avoiding the necessity for conventional subsequent precipitation and filtration removal steps.

Abstract: Process of extracting chromium from a chromium ore or concentrate by oxidation, which comprises suspending the chromium ore or concentrate in a bath of molten salts and introducing an oxygen-containing gas into the suspension in a sufficient amount and for a sufficient amount of time to oxidize chromium therein.

Abstract: A process for purifying concentrates of molybdenum oxide containing a variety of naturally-occurring contaminating metals, such as potassium, copper, calcium, magnesium, iron, aluminum, lead, zinc, bismuth, and the like, as well as compounds thereof, by roasting the impure concentrate at an elevated temperature in an oxygen atmosphere to convert sub-oxides of molybdenum to molybdenum trioxide and contaminating metal molybdites to corresponding metal molybdates, which are extracted by a hot aqueous leaching of the concentrate and the solubilized molybdate ions are recovered. The aqueous leached concentrate, after separation from the aqueous leach solution, is leached with an ammoniacal leach solution for converting the molybdenum trioxide constituent therein into soluble ammonium molybdate compounds, and the resultant leach solution is removed from the remaining insoluble residue, which is discarded.

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.

Abstract: An improved process for producing alkali metal chromates and dichromates wherein ferrochrome alloy containing at least 1% carbon by weight is reacted with a molten mixture of an alkali metal nitrate and an alkali metal carbonate at a temperature of at least 350.degree.C. The ferrochrome alloy can be prepared by smelting chromite ore in the presence of carbon.