Provided is a method for separating impurities and cobalt without using an electrolysis process from a cobalt chloride solution containing impurities and producing a high purity cobalt sulfate. The production method includes: a first solvent extraction step (S1) of bringing an organic solvent containing an alkyl phosphoric acid-based extractant into contact with a cobalt chloride solution containing impurities, and extracting zinc, manganese, and calcium into the organic solvent to separate to remove zinc, manganese, and calcium; a copper removal step (S2) of adding a sulfurizing agent to a cobalt chloride solution and generating a precipitate of sulfide of copper to separate to remove copper; a second solvent extraction step (S3) of bringing an organic solvent containing a carboxylic acid-based extractant into contact with a cobalt chloride solution and back extracting cobalt with sulfuric acid after extracting cobalt into the organic solvent to obtain cobalt sulfate solution; and a crystallization step (S4) of the cobalt sulfate solution obtained after having undergone through the second solvent extraction step (S3). These steps are sequentially executed. Without using an electrolysis process, a high purity cobalt sulfate is directly produced by separating cobalt and impurities containing manganese.

A method for processing positive electrode active material waste of lithium ion secondary batteries, the waste containing cobalt, nickel, manganese and lithium, the method including: a carbon mixing step of mixing the positive electrode active material waste in the form of powder with carbon to obtain a mixture having a ratio of a mass of carbon to a total mass of the positive electrode active material waste and the carbon of from 10% to 30%; a roasting step of roasting the mixture at a temperature of from 600° C. to 800° C. to obtain roasted powder; a dissolution step including a first dissolution process of dissolving lithium in the roasted powder in water or a lithium-containing solution, and a second dissolution process of dissolving the lithium in a residue obtained in the first dissolution process in water; and an acid leaching step of leaching a residue obtained in the lithium dissolution step with an acid.

The secondary amide contained in the extraction system consists of a single compound or a mixture of two or more compounds, wherein R.sub.1 is selected from a C2˜C12 alkyl, or a C3˜C12 cycloalkyl containing a single-ring structure, R.sub.2 is selected from a C1˜C11 alkyl, or a C3˜C11 cycloalkyl containing a single-ring structure; the total number of carbon atoms in the molecule is 12˜18. With a volume ratio of an organic phase and a brine phase being 1˜10:1, at a brine density of 1.25˜1.38 g/cm.sup.3 and at a temperature of 0˜50° C., a single-stage or multi-stage countercurrent extraction and a stripping are conducted to obtain a water phase with a low magnesium-lithium ratio, which is subjected to concentration, impurity removal and preparation to get lithium chloride, lithium carbonate and lithium hydroxide respectively. Water is used for stripping, greatly reducing the consumption of acid and base, and the separation process is shortened.

A method for recovering at least cobalt of valuable metals, cobalt and nickel, from an acidic solution obtained by subjecting waste containing positive electrode materials for lithium ion secondary batteries to a wet process, the acidic solution comprising cobalt ions, nickel ions and impurities, the method including: a first extraction step for Co recovery, the first extraction step being for extracting cobalt ions by solvent extraction from the acidic solution and stripping the cobalt ions; and a second extraction step for Co recovery, the second extraction step being for extracting cobalt ions by solvent extraction from a stripped solution obtained in the first extraction step for Co recovery and stripping the cobalt ions, wherein the first extraction step for Co recovery includes: a solvent extraction process for extracting cobalt ions in the acidic solution into a solvent; a scrubbing process for scrubbing the solvent that has extracted the cobalt ions; and a stripping process for stripping the cobalt ions in the solvent after the scrubbing into a solution.

A method for recovering at least cobalt of valuable metals, cobalt and nickel, from an acidic solution obtained by subjecting waste containing positive electrode materials for lithium ion secondary batteries to a wet process, the acidic solution comprising cobalt ions, nickel ions and impurities, wherein the method includes: a first extraction step for Co recovery, the first extraction step being for extracting cobalt ions by solvent extraction from the acidic solution and stripping the cobalt ions; an electrolytic step for Co recovery, the electrolytic step being for providing electrolytic cobalt by electrolysis using a stripped solution obtained in the first extraction step for Co recovery as an electrolytic solution; a dissolution step for Co recovery, the dissolution step being for dissolving the electrolytic cobalt in an acid; and a second extraction step for Co recovery, the second extraction step being for extracting cobalt ions by solvent extraction from a cobalt dissolved solution obtained in the dissolution step for Co recovery and stripping the cobalt ions.

A method for recovering at least cobalt of valuable metals, cobalt and nickel, from an acidic solution obtained by subjecting waste containing positive electrode materials for lithium ion secondary batteries to a wet process, the acidic solution comprising cobalt ions, nickel ions and impurities, wherein the method includes: a first extraction step for Co recovery, the first extraction step being for extracting cobalt ions by solvent extraction from the acidic solution and stripping the cobalt ions; an electrolytic step for Co recovery, the electrolytic step being for providing electrolytic cobalt by electrolysis using a stripped solution obtained in the first extraction step for Co recovery as an electrolytic solution; a dissolution step for Co recovery, the dissolution step being for dissolving the electrolytic cobalt in an acid; and a second extraction step for Co recovery, the second extraction step being for extracting cobalt ions by solvent extraction from a cobalt dissolved solution obtained in the dissolution step for Co recovery and stripping the cobalt ions.

The manufacture method disclosed herein includes: a preparation step of preparing a recovery object containing lithium and a first metal element; a chlorination heating step of heating the recovery object together with a metal chloride to produce LiCl; and a water dissolution step of immersing the recovery object after the chlorination heating step in water to dissolve LiCl in water to obtain a Li solution. In the manufacture method disclosed herein, a heating temperature in the chlorination heating step is 1000 C. or lower, and the metal chloride contains a second metal element that is more easily chlorinated than the first metal element in the recovered object and more hardly chlorinated than lithium in the chlorination heating step. Thereby, Li can be easily recovered from the recovery object at a low temperature of 1000 C. or lower.

The secondary amide contained in the extraction system consists of a single compound or a mixture of two or more compounds, wherein R.sub.1 is selected from a C2C12 alkyl, or a C3C12 cycloalkyl containing a single-ring structure, R.sub.2 is selected from a C1C11 alkyl, or a C3C11 cycloalkyl containing a single-ring structure; the total number of carbon atoms in the molecule is 1218. With a volume ratio of an organic phase and a brine phase being 110:1, at a brine density of 1.251.38 g/cm.sup.3 and at a temperature of 050 C., a single-stage or multi-stage countercurrent extraction and a stripping are conducted to obtain a water phase with a low magnesium-lithium ratio, which is subjected to concentration, impurity removal and preparation to get lithium chloride, lithium carbonate and lithium hydroxide respectively. Water is used for stripping, greatly reducing the consumption of acid and base, and the separation process is shortened.