Pyro-hydrometallurgical methods are described to economically and environmentally recover a target metal from iron slag or steel slag. For instance, the method can enable subjecting an iron or steel slag feed to acid-baking with an acid to produce a dried mixture comprising at least one soluble metal salts, then subjecting the dried mixture to water leaching to an aqueous solution comprising an aqueous leachate rich in said target metal and solid residues and subsequently separating the aqueous leachate rich in said target metal from the solid residues. This acid-baking water-leaching method facilitates efficient recovery of target metal compared to conventional methods.

The invention relates to powder metallurgy, in particular to a method for metallothermal reduction of feedstock elements made from feedstock being a solid solution of oxides of various elements in titanium oxide, using magnesium and/or calcium as reducing agents. Processes include hydrolysis of an aqueous solution of a titanium-containing salt to obtain primary particles of crystalline titanium oxide, calcination of a precipitate of titanium oxides/hydroxides, formation of feedstock elements from a milled powder of a solid solution of dopants in titanium oxide, reduction of feedstock elements in one step using calcium metal or reduction of feedstock elements in two steps, using magnesium metal or calcium metal in the first step, and calcium metal in the second step. The aim of the invention is to produce alloy powders of titanium metal with a particularly low oxygen content.

The invention relates to powder metallurgy, in particular to a method for metallothermal reduction of feedstock elements made from feedstock being a solid solution of oxides of various elements in titanium oxide, using magnesium and/or calcium as reducing agents. Processes include hydrolysis of an aqueous solution of a titanium-containing salt to obtain primary particles of crystalline titanium oxide, calcination of a precipitate of titanium oxides/hydroxides, formation of feedstock elements from a milled powder of a solid solution of dopants in titanium oxide, reduction of feedstock elements in one step using calcium metal or reduction of feedstock elements in two steps, using magnesium metal or calcium metal in the first step, and calcium metal in the second step. The aim of the invention is to produce alloy powders of titanium metal with a particularly low oxygen content.

The present invention provides a method for selective recovery of a valuable metal from a waste denitrification catalyst through alkali fusion, the method comprising the steps of: (a) adding an alkali metal to a waste denitrification catalyst, followed by mixing and alkali fusion, to generate a calcination product; (b) subjecting the calcination product to water-leaching to recover an alkali leachate and a residue; (c) adding a precipitator to the alkali leachate, followed by stirring, to recover calcium metavanadate (Ca(VO.sub.3).sub.2) or calcium tungstate (CaWO.sub.4) through precipitation; and (d) subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid. Therefore, vanadium and tungsten can be recovered at high efficiency by a method in which a precipitator is added to a leachate, which is obtained by adding an excess amount of an alkali metal to a waste denitrification catalyst and carrying out calcination and water-leaching, and then a reaction rate is controlled.

A process for recovering metal value-containing precipitates in consistently high concentrations from a metal-containing composition by combining selective roasting and leaching steps.

The present invention provides a method for selective recovery of a valuable metal from a waste denitrification catalyst through alkali fusion, the method comprising the steps of: (a) adding an alkali metal to a waste denitrification catalyst, followed by mixing and alkali fusion, to generate a calcination product; (b) subjecting the calcination product to water-leaching to recover an alkali leachate and a residue; (c) adding a precipitator to the alkali leachate, followed by stirring, to recover calcium metavanadate (Ca(VO.sub.3).sub.2) or calcium tungstate (CaWO.sub.4) through precipitation; and (d) subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid. Therefore, vanadium and tungsten can be recovered at high efficiency by a method in which a precipitator is added to a leachate, which is obtained by adding an excess amount of an alkali metal to a waste denitrification catalyst and carrying out calcination and water-leaching, and then a reaction rate is controlled.

The invention provides a method for the production of a metal, the method comprising the steps of mixing an oxide of the metal with a reducing agent comprising a Group II metal or a hydride thereof in the presence of water and/or an organic solvent, heating the mixture of oxide and reducing agent, leaching the resulting material with water; and washing the leached material with a dilute aqueous acid. Typically, the metal is a transition or rare earth metal, the oxide of the metal is an oxide of a transition or rare earth metal, and the reducing agent is selected from calcium or magnesium or the hydrides of calcium and magnesium. The metal is generally obtained at a purity of around 98.5-99.1%, and the method is much quicker than the methods of the prior art and has a much lower carbon footprint, thereby providing an option which is more sustainable, environmentally friendly, and accommodative for industries. Particularly good results are observed in the production of transition metals such as titanium, tantalum and niobium.

The present invention relates to a process for recovering a primary metal residue from a metal-containing composition.

Pyro-hydrometallurgical methods are described to economically and environmentally recover a target metal from iron slag or steel slag. For instance, the method can enable subjecting an iron or steel slag feed to acid-baking with an acid to produce a dried mixture comprising at least one soluble metal salts, then subjecting the dried mixture to water leaching to an aqueous solution comprising an aqueous leachate rich in said target metal and solid residues and subsequently separating the aqueous leachate rich in said target metal from the solid residues. This acid-baking water-leaching method facilitates efficient recovery of target metal compared to conventional methods.