A method with which Mg can be removed from aluminum alloy melt whose raw material is scrap or the like. Metal removal method includes processing step of forming molten salt layer in contact with aluminum alloy melt containing Mg which covers at least part of the surface of the aluminum alloy melt. This method allows Mg to be taken in from aluminum alloy melt to molten salt layer and removed. Molten salt layer contains specific halogen element that is one or more of Cl or Br and specific metal element that is one or more of Cu, Zn, or Mn. The specific metal element is supplied as an oxide of the specific metal element to the molten salt layer. At that time, the molten salt layer contains Mg. The step of removing Mg is performed by disposing a conductor that bridges the aluminum alloy melt and the molten salt layer.

A process may involve treating calcium sulfate separated from phosphoric acid with acid to obtain a suspension comprising purified calcium sulfate, separating the purified calcium sulfate in solid form from a liquid phase of the suspension, treating the purified calcium sulfate with water or with a salt- and/or chelate ligand-containing aqueous solution to leach rare earths out of the calcium sulfate, separating the further-purified calcium sulfate in solid form from the liquid phase of the suspension, mixing the purified calcium sulfate that is separated off with admixtures and reducing agents to obtain a raw meal mixture for cement clinker production, burning the raw meal mixture to obtain the cement clinker and thereby forming sulfur dioxide as offgas, and feeding the sulfur dioxide as raw material to sulfuric acid production to produce the sulfuric acid.

A method of extracting lithium from a lithium-containing solution according to an exemplary embodiment of the present invention includes: obtaining a lithium chloride solution from the lithium-containing solution; and crystallizing and removing sodium chloride in the obtained lithium chloride solution.

Disclosed is a system for producing magnesium hydroxide including: a generation unit; and a recovery unit connected to the generation unit, wherein the generation unit has a reaction tank in which a calcium hydroxide slurry is added to water to be treated containing magnesium ions to crystallize magnesium hydroxide and to obtain a reaction slurry containing particles of magnesium hydroxide, and a sedimentation tank in which the reaction slurry is reserved to sediment the particles and to separate the reaction slurry into a separation slurry containing the particles at a high concentration and a separation liquid containing the particles at a low concentration, and wherein, in the recovery unit, an alkaline aqueous solution is added to the separation liquid to crystallize magnesium hydroxide and to obtain the reaction slurry and then the reaction slurry is reserved to sediment the particles and to recover the sedimented particles.

A system for producing magnesium chloride includes a removal unit, and a concentration unit that is connected to the removal unit. The removal unit generates feedstock water by removing sulfate ions and sodium ions from treatment target water having seawater as a feedstock. The concentration unit generates a slurry in which magnesium chloride is crystallized by concentrating the feedstock water. The removal unit has a first removal unit which reduces the sulfate ion concentration compared to the sulfate ion concentration in the treatment target water, and a second removal unit which reduces the sodium ion concentration compared to the sodium ion concentration in the treatment target water.

A system and method that uses a high-temperature condenser to collect magnesium produced by thermal reduction, electrolysis, or distillation. The condenser is a common heat exchanger design (shell/tube, plate/plate, etc.) and uses a heat transfer fluid to cool and condense magnesium gas, e.g., to 200-900° C. under vacuum or pressure conditions. Solid or liquid magnesium is collected in the condenser along with any by-products or impurities at a purity greater than 35 wt-% Mg. Magnesium is subsequently liberated from the condenser by raising the temperature of the system, lowering the pressure, or both, to induce a phase change in the metal, such as melting or distillation, for further purification to, e.g., >90 wt-% Mg.

A process for producing alumina and a lithium salt comprising the steps of: (a) calcining an alpha spodumene ore or concentrate to produce beta spodumene; and (b) (I) leaching beta spodumene from the calcining step (a) with an alkaline solution under pressure; or (II) sulphating beta spodumene with at least sodium sulphate and leaching said sulphated beta spodumene to produce a lithium containing solution and a zeolitic residue. The lithium containing solution is treated to provide a purified lithium salt and said zeolitic residue is treated to provide high purity alumina.

There is provided a method for collecting and reusing an active material from positive electrode scrap. The method for reusing a positive electrode active material of the present disclosure includes (a) thermally treating positive electrode scrap comprising an active material layer on a current collector in air for thermal decomposition of a binder and a conductive material in the active material layer, to separate the current collector from the active material layer, and collecting an active material in the active material layer, (b-1) washing the active material collected from the step (a) with a lithium compound solution which is basic in an aqueous solution, (b-2) mixing the active material washed from the step (b-1) with a lithium precursor aqueous solution and spray drying, and (c) annealing the active material spray dried from the step (b-2) to obtain a reusable active material.

A method for recovering platinum group metals, includes melting a material to be treated containing platinum group metals, under heating in a furnace, along with a copper source material containing at least one kind of metallic copper and copper oxide, a flux component, and a reducing agent. The molten metal absorbing the platinum group metals is separated from a slag oxide through difference in specific gravity. The molten metal absorbing the platinum group metals is subjected to an oxidation treatment. An oxide layer containing as a major component copper oxide and a molten metal containing as a major component metallic copper containing the platinum group metals concentrated therein are separated through difference in specific gravity. A silver content in the molten metal separated in melting under heating is controlled to 2,000 ppm or more and 8,000 ppm or less, thereby recovering platinum group metals with high efficiency.

There is provided a method for collecting and reusing an active material from positive electrode scrap. The positive electrode active material reuse method of the present disclosure includes (a) thermally treating positive electrode scrap comprising an active material layer on a current collector in air for thermal decomposition of a binder and a conductive material in the active material layer, to separate the current collector from the active material layer, and collecting an active material in the active material layer, (b) washing the collected active material using a lithium precursor aqueous solution which is basic in an aqueous solution and drying, and (c) annealing the washed active material to obtain a reusable active material.