Abstract: A process for treating a sludge comprises digesting the waste material with a mixture of sulfuric acid and hydrogen peroxide to form an acidic digestion solution and a digestion residue. The digestion residue containing the major portion of tungsten and other refractory metals is reacted with NaOH to solubilize the major portion of tungsten values to a liquid concentrate that is separated from the insoluble solid that contains the major portion of the other refractory metals such as tantalum and niobium. The digestion solution containing the major portion of the transition and rare metals is treated with a base to selectively recover iron as a solid iron hydroxide precipitate which is separated from the resulting liquor. The liquor is then treated again with a base to selectively recover the other metals such as Sc, Cr, rare earths, but not Mn, as a solid metal hydroxide precipitate that is separated from the solution.

Abstract: A process is disclosed for purifying scandium from an acid solution containing scandium and various impurities. The process involves mixing the acid solution with a chelating resin in the hydrogen form to from a slurry and packing the slurry in a short ion exchange column. The ion exchange column is rinsed with a mineral acid and the scandium is removed by passing diglycolic acid through the column. The diglycolic acid containing scandium is then passed through a chelating resin in the H form. When the scandium concentration in the effluent from the chelating resin reaches a preselected level the effluent of digylcolic acid and scandium is collected. Collection is stopped when the scandium concentration in the eluent falls below a preselected level. This collected eluent is passed through a strong cation exchange column where the scandium is collected.

Abstract: A process for eliminating an industrial waste sludge by converting its metal values into useful products involves the selective leaching of Mn, divalent Fe, and other valuable metals, such as Sc, Co, Cr, Ni, Th, rare earths, etc. with a mixture of dilute sulfuric acid and a reductant at ambient temperature. Scandium is recovered by passing the leachate through an ion exchange column which is packed with a weakly cationic resin. The retention of other metals on the resin column is negligible. The scandium is eluted from the resin column and converted to a solid product. The raffinate from the ion exchange column is titrated with an alkali solution to convert the metals, except divalent Mn and Fe, to a solid metal hydroxide. After the separation the filtrate is treated with an alkali and an oxidant to recover iron as a solid product of iron oxide which is separated from the solution.

Abstract: A process for recovering the scandium present as a trace constituent in a mixture of iron, manganese and other oxides comprise bringing the scandium into solution along with much of the other base metals, reducing the dissolved iron to the ferrous state, adjusting the pH of the resulting solution to a value of about 2.0 and selectively extracting the scandium with an organic extractant consisting of thenoyltrifluoroacetone dissolved in an aromatic solvent. The scandium values are recovered quantitatively from the organic extractant by treating it with a dilute acid. The process effects a complete separation of the scandium from the base metals resulting in a scandium product of high purity.

Abstract: A method of recovering quantitatively trace amounts of scandium from aqueous solutions containing large amounts of other metals consists of reducing any manganese and iron in the solution to the divalent states of manganese and iron. The solution is then adjusted to a pH from about 1.9 to about 2.1 and passed through a column of the ion exchange resin in the hydrogen form having an iminodiacetic acid functionality. The scandium is absorbed on the column and any base metals and rare earth metals which were also absorbed are removed by eluting with a dilute acid without removing the scandium. The scandium is subsequently removed from the column by eluting with a solution containing a chelating agent such as diglycolic acid. The scandium is then recovered from the solution by precipitation, filtering, washing, drying and calcined to the oxide.

Abstract: A method for a quantitative separation of scandium from thorium comprises adsorption of both metals on a cation exchange resin followed by selective elution of scandium with an acidic solution of a chelating agent followed by the elution of thorium by a six normal hydrochloric acid solution.

Abstract: A process for the preparation of silicon nitride powders, which are suitable for the manufacture of high quality structural ceramics is described. The synthesis process is based on the reduction of silicon dioxide by carbon in a nitrogen stream at elevated temperatures to form alpha silicon nitride. Silicon nitride powders of various morphologies are obtained by this technique by varying either the type of reactants used or the process conditions. Structural ceramics with densities exceeding 99% of theoretical and having satisfactory mechanical strength and oxidation resistance were sintered from powders synthesized by the method of this invention.

Abstract: A process for the growth of silicon nitride whiskers consists of reacting a mixture of carbon and silicon dioxide powders at elevated temperature in a stream of nitrogen, said reaction mixture containing small amounts of metals such as chromium, magnesium, and nickel which promote the growth of silicon nitride whiskers by vapor phase transport. The whiskers obtained as a result of this invention are of much higher purity than those obtained by prior art.

Abstract: Molybdenum is removed from an aqueous solution containing tungsten and molybdenum by extracting the molybdenum from the aqueous solution having a pH greater than 8.5 with a liquid organic extractant containing a preferred complexing agent, 3,4-dimercaptotoluene.

Abstract: A process for cleanly separating tungsten and the coinage metals from alloys or mixtures thereof comprises electrowinning the coinage metal from an electrolyte solution which is maintained substantially free of tungsten contamination by contacting the electrolyte solution with an organic extractant to remove the tungsten. A preferred extractant solution comprises a quaternary alkyl ammonium salt or quaternary alkyl phosphonium salt dissolved in an inert organic solvent.

Abstract: A process for cleanly separating coinage metals from alloys of coinage metals and tungsten comprises electrowinning the coinage metal from an electrolyte solution which is contacted with an ion exchange resin to selectively remove the tungsten.

Abstract: A method of recovering molybdenum from the catalyst residue derived from the process of epoxidizing olefins is disclosed. The catalyst residue, in semi-solid form or as a solution diluted in an organic solvent, is contacted with an aqueous solution of an oxidizing agent such as hydrogen peroxide, nitric acid, or sodium hypochlorite to transfer the molybdenum to the aqueous solution. The molybdenum is thereafter isolated directly from the aqueous solution or, alternatively, from the aqueous solution following preconcentration by liquid-liquid or liquid-solid extraction.

Abstract: A process for recovering tungsten from low level sources such as naturally occurring brines in a form substantially free of contaminating boron comprises adjusting the pH of the source solution to a value below about pH 8, contacting the pH-adjusted solution with an ion exchange resin, preferentially eluting the tungsten values in an aqueous eluate, extracting the eluate solution with an organic extractant comprising o-mercaptobenzoic acid, a quaternary alkylammonium salt and an inert organic solvent, and stripping the tungsten-loaded organic extractant solution with an aqueous basic stripping solution.

Abstract: A recyclable process for the recovery of tungsten from low level aqueous sources comprises adjustment of the pH of the source solution to a value below about pH 6, extraction of the tungsten values into an organic phase comprising a chelating agent, an organic transfer agent, and an inert organic solvent. Preferred chelating agents include vicinally disubstituted aromatic compounds in which the substituents are selected from amino, carboxyl, hydroxyl, and sulfhydryl.

Abstract: In a resin sorption process for recovering tungsten from solutions containing high levels of contaminating boron by employing a resin copolymer of 8-hydroxyquinoline, a polyamine, resorcinol, and formaldehyde (HPRF resins), the improvement comprises a two step desorption of metal values from the loaded resin consisting of a first step of washing the loaded resin with a solution of a weakly acidic salt to remove a portion of the boron from the loaded resin, followed by a second step of washing the loaded resin with a solution of a weakly basic salt to remove a portion of the tungsten from the loaded resin, whereby the tungsten recovered is substantially free of contaminating boron.