A process for recovering non-ferrous metals from a solid matrix may include: (a) leaching the solid matrix with an aqueous-based solution containing chloride ions, ammonium ions, and Cu.sup.2+ ions, having a pH of 6.5-8.5, in a presence of oxygen, at a temperature of 100 C.-160 C. and a pressure of 150 kPa-800 kPa, so as to obtain an extraction solution comprising leached metals and solid leaching residue; (b) separating the solid leaching residue from the extraction solution; and/or (c) subjecting the extraction solution to at least one cementation so as to recover the leached metals in elemental state. The pH may be greater than or equal to 6.5 and less than or equal to 8.5. Temperature may be greater than or equal to 100 C. and less than or equal to 160 C. Pressure may be greater than or equal to 150 kPa and less than or equal to 800 kPa.

The present invention provides an aqueous cobalt chloride solution purification method, in which impurities can be efficiently removed from a cobalt salt solution.

Provided is a method for 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. When the passive film is removed, 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. In addition, since the metallic nickel is only brought into contact with the aqueous solution containing cobalt chloride, the impurity can be easily removed from the aqueous solution containing cobalt chloride.

The present invention provides an aqueous cobalt chloride solution refinement method, in which impurities can be efficiently removed from a cobalt salt solution.

Disclosed is a method for bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove an impurity by a cementation reaction, in which the metallic nickel is washed with an acidic liquid having a pH of not more than 2.5 before the metallic nickel is brought into contact with the aqueous solution containing cobalt chloride. Since the metallic nickel is washed with the acidic liquid having a pH of not more than 2.5, a passive film on a surface of the metallic nickel is removed. The passive film is removed from the metallic nickel, and therefore, when the metallic nickel comes in contact with the aqueous solution containing cobalt chloride, an impurity more noble than the metallic nickel can be precipitated by the cementation reaction. In addition, since the metallic nickel is only washed with acid to be brought into contact with the aqueous solution containing cobalt chloride, the impurity can be easily removed from the aqueous solution containing cobalt chloride.

A process for recovering non-ferrous metals from a solid matrix may include: leaching the solid matrix with an aqueous-based solution, in a presence of oxygen, to obtain an extraction solution including leached metals and solid leaching residue; separating the solid leaching residue from the extraction solution; and subjecting the extraction solution to at least one cementation to recover the leached metals in elemental state. The leaching solution may include chloride ions. The leaching solution may further include ammonium ions. A pH of the leaching solution may be greater than or equal to 6.5 and less than or equal to 8.5. A leaching temperature may be greater than or equal to 100 C. and less than or equal to 160 C. A leaching pressure may be greater than or equal to 150 kPa and less than or equal to 800 kPa.

The present invention provides a hydrometallurgical method for nickel oxide ore, wherein the plant can be smoothly started up without imposing a load onto a filter cloth for a separation treatment of zinc sulfide, and the amount of residual zinc in a mother liquor for nickel recovery can be reduced to 1 mg/L. In the plant start-up after the completion of a periodic inspection, a post-neutralization solution is controlled to return to a neutralization reaction tank via circulation piping by adjustment of a switching valve in flow piping without sulfurizing post-neutralization solution. When the flow rate and/or the temperature of the post-neutralization solution circulated reaches a predetermined value, a sulfurization treatment is applied to the post-neutralization solution in the dezincification reaction tank to form zinc-sulfide-containing mother liquor for nickel recovery and adjust the switching valve. Zinc-sulfide-containing mother liquor for nickel recovery is transferred to a filter apparatus via transfer piping.

The present invention provides a method for removing copper from lithium ion battery scrap containing copper, comprising a leaching step of adding the lithium ion battery scrap to an acidic solution and leaching the lithium ion battery scrap under a condition that an aluminum solid is present in the acidic solution; and a copper separating step of separating copper contained in the acidic solution as a solid from the acidic solution, after the leaching step.

The present disclosure concerns a process for the recovery of valuable metals from polymetallic nodules. A two-stage process using SO.sub.2 in an acidic aqueous media is disclosed. In a first step, performed in mildly acidic conditions, Mn, Ni, and Co are dissolved; in a second, more acidic step, Cu is dissolved. Under these conditions, the leachate of the first step contains most of the Mn, Ni, and Co, while being nearly Cu-free. The Ni and Co are precipitated as sulfides; the Mn can be recovered as sulfate by crystallization. Cu, which is leached in the second step, is selectively precipitated, also as sulfide.

Provided is a method of producing high-purity nickel sulfate by an impurity-element removal method for selectively removing Mg from a Ni-containing solution. The method comprises a production process of producing nickel sulfate from a Ni-containing acid solution, the acid solution being treated in order of steps (1) to (3): (1) carbonation step, adding a carbonating agent into the Ni-containing solution to make Ni contained in the Ni-containing solution into a precipitate of nickel carbonate or a mixture of nickel carbonate and nickel hydroxide, thereby forming a slurry after carbonation including the precipitate and a solution after carbonation; (2) solid-liquid separation step, separating the slurry after carbonation formed in the carbonation step into the precipitate and the solution after carbonation; and (3) neutralization step, adding a neutralizing agent into the solution after carbonation separated through the solid-liquid separation step to recover Ni contained in the solution after carbonation as a Ni-precipitate.

A process has been developed in order to recover and recycle the metals present in spent batteries, including alkaline spent batteries alone or mixed with other types of spent batteries. This method shows a good potential in terms of metals recoveries efficiencies and economic feasibility. Firstly, the spent batteries are crushed (optionally after having been frozen in the case of spent batteries of mixed types). Then, the undesirable parts (plastics, steel cases, papers, etc.) are removed by screening. The collected powder, containing the metals, is mixed with a solution of sulfuric acid in the presence of a reducing agent. The solid/liquid separation is carried out by filtration and the leachate is purified in order to selectively recover the metals. The purification steps consist of: a) recovering Zn by solvent extraction followed by an electrowinning process; b) simultaneously recovering Mn and Cd by solvent extraction process; c) selectively recovering Cd from the mixture solution of Cd and Mn by electrowinning process; d) precipitating Mn from a pure solution of MnSO.sub.4 in a carbonate form; e) removing the impurities present in the effluent by solvent extraction in order to obtain a pure NiSO.sub.4 solution; f) precipitating Ni from a NiSO.sub.4 solution in a carbonate form.

The present description relates to a process for producing magnesium metal from magnesium-bearing ores using serpentine. The process described herein consists generally in a mineral preparation and classification followed by leaching with dilute hydrochloric acid. The slurry is filtered and the non-leached portion, containing amorphous silica is recovered. The residual solution is neutralized and purified by chemical precipitation with non activated and activated serpentine. The nickel is also recovered by precipitation at higher pH. A final neutralisation and purification step of magnesium chloride solution by precipitation allows eliminating any traces of residual impurities. The purified magnesium chloride solution is evaporated until saturation and the MgCl.sub.2.6H.sub.2O is recovered by crystallization in an acid media. The salt is dehydrated and subsequent electrolysis of anhydrous magnesium chloride produces pure magnesium metal and hydrochloric acid.