A method of recovering calcium and a rare earth metal from slag includes: a step (S100) for forming alkali silicate by performing alkali fusion on slag including silicon (Si), calcium (Ca), and a rare earth metal and reacting the silicon with an alkali metal salt; a step (S200) for removing the silicon and other impurities from the slag by leaching and separating the alkali silicate using distilled water; a step (S300) for leaching, into an acid solution, the calcium and the rare earth metal included in the slag from which the silicon and the other impurities are removed; and a step (S400) for recovering the calcium and the rare earth metal leached into the acid solution.

The present invention provides a method for recovery, extraction and separation of rare earth elements from rare earth containing materials such as ore and tailings. In accordance with preferred embodiments, the method of the present invention includes grinding rare earth-containing ores to form ore powder and leaching the powered ore with at least one mineral acid. Further, the method of the present invention includes forming a leach solution of metal ions, forming an aqueous-metal concentrate, and precipitating the aqueous-metal concentrate to selectively remove the metal ions from the leach solution. Further, the method of present invention includes the steps of obtaining a precipitate of the rare earth elements, mixing the precipitate with ammonium salt and subjected the mixture to an electrowinning process.

The present invention relates to cerium oxide particles that have excellent heat resistance especially useful for catalysts, functional ceramics, solid electrolyte for fuel cells, polishing, ultraviolet absorbers and the like, and particularly suitable for use as a catalyst or co-catalyst material, for instance in catalysis for purifying vehicle exhaust gas. The present invention also relates to a method for preparing such cerium oxide particles, and a catalyst, such as for purifying exhaust gas, utilizing these cerium oxide particles.

The present invention relates to silicon coated metal microparticles in which at least a part of a surface of a metal microparticle composed of at least one of metal elements or metalloid elements is coated with silicon, wherein the silicon coated metal microparticles are a product obtained by a reduction treatment of silicon compound coated precursor microparticles in which at least a part of a surface of a precursor microparticle containing a precursor of the metal microparticles is coated with a silicon compound, or silicon doped precursor microparticles containing a precursor of the metal microparticles. Because it is possible particularly to strictly control a particle diameter of the silicon compound coated metal microparticle by controlling conditions of the reduction treatment, design of a more appropriate composition can become facilitated, compared with a conventional composition, in terms of diversified usages and desired properties of silicon compound coated metal microparticles.

A composite solid state electrolyte comprises a polymer electrolyte material, a ceramic ion conductor, and a functionalized coupling agent selected to be compatible with the ceramic ion conductor and the bulk polymer compound. The polymer electrolyte material comprises a bulk polymer compound and a lithium salt. The functionalized coupling agent has a backbone that is structurally similar to the bulk polymer compound.

The present invention relates to silicon-compound-coated fine metal particles, with which surfaces of fine metal particles, composed of at least one type of metal element or metalloid element, are at least partially coated with a silicon compound and a ratio of SiOH bonds contained in the silicon-compound-coated fine metal particles is controlled to be 0.1% or more and 70% or less. By the present invention, silicon-compound-coated fine metal particles that are controlled in dispersibility and other properties can be provided by controlling the ratio of SiOH bonds or the ratio of SiOH bonds/SiO bonds contained in the silicon-compound-coated fine metal particles. By controlling the ratio of SiOH bonds or the ratio of SiOH bonds/SiO bonds, a composition that is more appropriate for diversifying applications and targeted properties of silicon-compound-coated fine metal particles than was conventionally possible can be designed easily.

With an aim to provide a method for producing an oxide particle with controlled color characteristics and also provide an oxide particle with controlled color characteristics, the present invention provides a method for producing an oxide particle, wherein the color characteristics of the oxide particle are controlled by controlling a ratio of an M-OH bond between an element (M) and a hydroxide group (OH) or an M-OH bond/M-O bond ratio, where the element (M) is one element or plural different elements other than oxygen or hydrogen included in the oxide particle selected from metal oxide particles and semi-metal oxide particles. According to the present invention, by controlling the M-OH bond or the M-OH bond/M-O bond ratio of the metal oxide particle or the semi-metal oxide particle, the oxide particle with controlled color characteristics of any of reflectance, transmittance, molar absorption coefficient, hue, and saturation can be provided.

The invention relates to a method for producing a scandium-containing concentrate from the wastes of alumina production and extracting high-purity scandium oxide from the same. Provided is a method for producing a scandium-containing concentrate from a red mud, wherein the Sc.sub.2O.sub.3 content therein is least of 15 wt. % (in terms of dry matter), the TiO.sub.2 content not more than 3 wt. % (in terms of dry matter), the ZrO.sub.2 content not more than 15 wt. % (in terms of dry matter), and wherein scandium in the concentrate is in form of a mixture of Sc(OH).sub.3 hydroxide with ScOHCO.sub.34H.sub.2O. Also provided is a method for producing high-purity scandium oxide, with a purity of approximately 99 wt. %.

The present invention is a method of producing silicon compound coated oxide particles in which at least a part of a surface of a metal oxide particle is coated with a silicon compound, wherein wettability and color characteristics are controlled by controlling a ratio of SiOH bonds contained in the silicon compound coated oxide particles. By the present invention, silicon compound coated oxide particles having controlled wettability such as hydrophilicity, water repellency or oil repellency, and controlled color characteristics of either reflectivity, molar absorption coefficient or transmittance can be provided.

With an aim to provide an oxide particle with controlled color characteristics, the present invention provides a method for producing an oxide particle, wherein the color characteristics of the oxide particle are controlled by controlling a M-OH bond/M-O bond ratio, which is a ratio of a M-OH bond between an element (M) and a hydroxide group (OH) to a ratio of an M-O bond between the element (M) and oxygen (O), where the element (M) is one or plural different elements other than oxygen or hydrogen included in the oxide particle selected from metal oxide particles and semi-metal oxide particles. According to the present invention, by controlling the M-OH bond/M-O bond ratio of the metal oxide particle or the semi-metal oxide particle, the oxide particle with controlled color characteristics of any of reflectance, transmittance, molar absorption coefficient, hue, and saturation can be provided.