An aqueous cobalt chloride solution purification method, in which impurities can be efficiently removed from a cobalt salt solution, includes bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove an impurity by a substitution reaction, in which the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5. Since the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5, a passive film on a surface of the metallic nickel can be effectively removed, and the metallic nickel comes in contact with the aqueous solution containing cobalt chloride, so that an impurity more noble than the metallic nickel can be precipitated by the substitution reaction. The metallic nickel is only brought into contact with the aqueous solution containing cobalt chloride, and the impurity can be easily removed.

An aqueous cobalt chloride solution purification method, in which impurities can be efficiently removed from a cobalt salt solution, includes bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove an impurity by a substitution reaction, in which the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5. Since the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5, a passive film on a surface of the metallic nickel can be effectively removed, and the metallic nickel comes in contact with the aqueous solution containing cobalt chloride, so that an impurity more noble than the metallic nickel can be precipitated by the substitution reaction. The metallic nickel is only brought into contact with the aqueous solution containing cobalt chloride, and the impurity can be easily removed.

The present invention provides a method of recovering copper and zinc from an aqueous sulfate and chloride containing solution. In the first process step zinc and copper are simultaneous extracting with an extraction solution comprising a liquid chelating cation exchanger and a liquid anion exchanger. The extraction is followed by consecutive stripping stages. First the anionic species are washed from the organic phase with one or more aqueous solutions and finally the copper is stripped with an aqueous acidic solution.

The present invention provides a method of recovering copper and zinc from an aqueous sulfate and chloride containing solution. In the first process step zinc and copper are simultaneous extracting with an extraction solution comprising a liquid chelating cation exchanger and a liquid anion exchanger. The extraction is followed by consecutive stripping stages. First the anionic species are washed from the organic phase with one or more aqueous solutions and finally the copper is stripped with an aqueous acidic solution.

Methods for recovering gold from gold-bearing materials are provided. The methods rely upon on the self-assembly of KAuBr.sub.4 and -cyclodextrin (-CD) in aqueous solution to form a co-precipitate, a 1:2 complex, KAuBr.sub.4(-CD).sub.2 (Br), either alone or in an extended {[K(OH.sub.2).sub.6][AuBr.sub.4](-CD).sub.2}.sub.n chain superstructure (FIG. 1). The co-precipitation of Br is selective for gold, even in the presence of other metals, including other square-planar noble metals. The method enables one to isolate gold from gold-bearing materials from diverse sources, as further described.

Methods for recovering gold from gold-bearing materials are provided. The methods rely upon on the self-assembly of KAuBr.sub.4 and -cyclodextrin (-CD) in aqueous solution to form a co-precipitate, a 1:2 complex, KAuBr.sub.4(-CD).sub.2 (Br), either alone or in an extended {[K(OH.sub.2).sub.6][AuBr.sub.4](-CD).sub.2}.sub.n chain superstructure (FIG. 1). The co-precipitation of Br is selective for gold, even in the presence of other metals, including other square-planar noble metals. The method enables one to isolate gold from gold-bearing materials from diverse sources, as further described.

The present invention relates to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, more particularly, to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, the method including: filtering a leaching solution of a spent catalyst, providing the filtered leaching solution into a concentration chamber, and heating the filtered leaching solution to recover acid included in the leaching solution; providing a concentrated solution of the leaching solution into a substitution chamber after recovering the acid, and adding a metal for a substitution reaction; and cleaning a solid, which is separated by solid-liquid separation after the substitution reaction, with acid and recovering the platinum group metal.

The present invention relates to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, more particularly, to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, the method including: filtering a leaching solution of a spent catalyst, providing the filtered leaching solution into a concentration chamber, and heating the filtered leaching solution to recover acid included in the leaching solution; providing a concentrated solution of the leaching solution into a substitution chamber after recovering the acid, and adding a metal for a substitution reaction; and cleaning a solid, which is separated by solid-liquid separation after the substitution reaction, with acid and recovering the platinum group metal.

The present disclosure discloses a method for extracting lithium from waste lithium batteries, which comprises: leaching positive electrode powder of the waste lithium battery in hydrochloric acid, and obtaining leaching solution by filtering; removing copper and iron from the leaching solution, and then introducing hydrogen sulfide gas for reaction, and performing solid-liquid separation to obtain first filter residue and first filtrate; adding potassium permanganate to the first filtrate, and performing solid-liquid separation to obtain second filter residue and second filtrate; performing spray pyrolysis on the second filtrate to obtain solid particles and tail gas, washing the solid particles with water to obtain a lotion, washing and collecting the tail gas and then mixing the tail gas with the lotion to obtain lithium salt solution. In the present disclosure, the positive electrode powder is leached with hydrochloric acid to obtain the hydrochloric acid leaching solution, and hydrogen sulfide is used to precipitate nickel and cobalt after removing the copper and iron impurities in the leaching solution in turn, and potassium permanganate is added to precipitate manganese ions to generate manganese dioxide. Spray pyrolysis converts the aluminum and magnesium in the solution into oxides and lithium salt is separated. The entire reaction process does not require organic solvent extraction and reduces the loss of lithium.

Digestion of a laterite with sulfuric acid dissolves all constituents except silica. The resulting sulfatesaluminum sulfate, ferric sulfate, titanyl sulfate, and magnesium sulfateremain in solution at approximately 90 C. Hot filtration separates silica. Solution flow over iron reduces ferric sulfate to ferrous sulfate. Controlled ammonia addition promotes hydrolysis and precipitation of hydrated titania from titanyl sulfate that is removed by filtration. Addition of ammonium sulfate forms ferrous ammonium sulfate and ammonium aluminum sulfate solutions. Alum is preferentially separated by crystallization. Addition of ammonium bicarbonate to an ammonium alum solution precipitates ammonium aluminum carbonate which may be heated to produce alumina, ammonia, and carbon dioxide. The addition of oxalic acid generates insoluble ferrous oxalate which thermally decomposes to ferrous oxide and carbon monoxide which is used to reduce the ferrous oxide to metallic iron. Further oxalic acid addition precipitates magnesium oxalate which is thermally decomposed to magnesium oxide.