The present invention provides a process for preparing a high-purity nickel sulphate solution, comprising the steps of: i. forming an aqueous mixed metal sulphate solution by reacting sulphuric acid with a raw material feed comprising nickel, manganese, cobalt, and magnesium in an aqueous medium; ii. extracting manganese from said aqueous mixed metal sulphate solution, thereby obtaining a first aqueous raffinate comprising nickel, cobalt and magnesium, and a manganese-rich organic phase; iii. extracting cobalt from said first aqueous raffinate, thereby obtaining a second aqueous raffinate comprising nickel and magnesium, and a cobalt-rich organic phase; and iv. extracting magnesium from said second aqueous raffinate solution, thereby obtaining a high-purity nickel sulphate solution, and a magnesium-rich organic phase.

A method for recycling lithium batteries containing the steps: (a) digesting comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100 C., in particular at least 140 C., so that waste gas (14) and a digestion material (16) are produced, (b) discharging the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

A method for reducing waste by recovering transition metal of a lithium secondary battery of the present invention includes preparing a cathode active material from a cathode of the lithium secondary battery, producing a first leachate by treating the cathode active material with a first acidic solution containing a reducing agent in an amount smaller than an amount corresponding to a reaction equivalent of the cathode active material, and producing a second leachate by treating the remaining cathode active material, which excludes a fraction contained in the first leachate, with a second acidic solution containing a reducing agent. Accordingly, extraction rate of manganese and purity of cobalt may be improved.

The present invention provides a process for preparing a high-purity nickel sulphate solution, comprising the steps of: i. forming an aqueous mixed metal sulphate solution by reacting sulphuric acid with a raw material feed comprising nickel, manganese, cobalt, and magnesium in an aqueous medium; ii. extracting manganese from said aqueous mixed metal sulphate solution, thereby obtaining a first aqueous raffinate comprising nickel, cobalt and magnesium, and a manganese-rich organic phase; iii. extracting cobalt from said first aqueous raffinate, thereby obtaining a second aqueous raffinate comprising nickel and magnesium, and a cobalt-rich organic phase; and iv. extracting magnesium from said second aqueous raffinate solution, thereby obtaining a high-purity nickel sulphate solution, and a magnesium-rich organic phase.

A method for recovering metals from a metal-containing solution containing nickel ions, lithium ions, and anions of an inorganic acid, the method including: a nickel extraction step including extraction that mixes the metal-containing solution with a solvent while adjusting an equilibrium pH using a pH adjusting agent containing lithium ions, transfers the nickel ions in the metal-containing solution to the solvent, and separates the solvent containing the nickel ions from an extracted solution, wherein in the nickel extraction step, the extraction is carried out under conditions where the total of a lithium ion concentration of the metal-containing solution and a lithium ion concentration of the pH adjusting agent is less than or equal to a lithium ion concentration of a saturated solution of a lithium salt made of the anions of the inorganic acid and the lithium ions contained in the metal-containing solution.

Methods of recovering a nickel salt are disclosed. The method includes removing one or more impurities from an aqueous leach solution including cobalt, manganese, and nickel salts to produce a first purified aqueous solution including the cobalt, manganese, and nickel salts. The method includes extracting the cobalt and manganese salts from the first purified aqueous solution in a first liquid-liquid extraction step using a first organic extractant to produce an aqueous raffinate solution including the nickel salt and a first loaded organic solution including the cobalt and manganese salts. The method further includes extracting the nickel salt from the aqueous raffinate solution in a second liquid-liquid extraction step using a second organic extractant to produce a second loaded organic solution including the nickel salt. Systems for recovering a nickel salt are also disclosed.

A method for recycling lithium batteries containing the steps: (a) digesting comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100 C., in particular at least 140 C., so that waste gas (14) and a digestion material (16) are produced, (b) discharging the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

A method provides for separating nickel from an aqueous solution using an organicaqueous extraction by performing one or more liquid-liquid extraction stages performed using an input aqueous solution comprising lithium ions, nickel ions, and cobalt ions and/or manganese ions, wherein each extraction stage comprises mixing an aqueous phase with dissolved metal sulfate with an organic solvent having dissolved di-(2,4,4-trimethylpentyl) phosphinic acid from 30% to 70% hydroxyl saponified with alkali, NH.sub.4.sup.+ or nickel counter ions. A collected purified aqueous phase comprising at least 90% of the nickel from the input aqueous solution and no more than about 5% of the each of the cobalt and manganese. The input aqueous solution is prepared from recovered lithium ion battery material.