Method for producing mixed metal salt
A method for producing mixed metal salts containing manganese ions and at least one of cobalt ions and nickel ions, the method including: an Al removal step of subjecting an acidic solution containing at least manganese ions and aluminum ions, and at least one of cobalt ions and nickel ions, to removal of the aluminum ions by extracting the aluminum ions into a solvent, the acidic solution being obtained by subjecting battery powder of lithium ion batteries to a leaching step; and a precipitation step of neutralizing an extracted residual liquid obtained in the Al removal step under conditions where a pH is less than 10.0, to precipitate mixed metal salts comprising a metal salt of manganese and a metal salt of at least one of cobalt and nickel.
1 . A method for producing mixed metal salts comprising manganese ions and at least one of cobalt ions and nickel ions, the method comprising:
an Al removal step of subjecting an acidic solution comprising at least manganese ions and aluminum ions, and at least one of cobalt ions and nickel ions, to removal of the aluminum ions by extracting the aluminum ions into a solvent, the acidic solution is obtained by subjecting battery powder of lithium ion batteries to a leaching step; and
a precipitation step of neutralizing an extracted residual liquid obtained in the Al removal step under conditions where a pH is less than 10.0, to precipitate mixed metal salts comprising a metal salt of manganese and a metal salt of at least one of cobalt and nickel,
wherein a metal extraction step of extracting and back-extracting at least one of cobalt, nickel and manganese is not carried out between the Al removal step and the precipitation step.
2 . The method for producing mixed metal salts according to claim 1 , wherein, in the precipitation step, sodium hydroxide is used for neutralization of the extracted residual liquid, and the mixed metal salts comprises a hydroxide of manganese and a hydroxide of at least one of cobalt hydroxide and nickel hydroxide.
3 . The method for producing mixed metal salts according to claim 1 ,
wherein the acidic solution further comprises one or more metal ions selected from the group consisting of magnesium ions, sodium ions, lithium ions and calcium ions, and
wherein, in the precipitation step, the metal ions are left in the liquid without precipitating the metal ions.
4 . The method for producing mixed metal salts according to claim 1 , wherein, in the precipitation step, a pH of the extracted residual liquid is adjusted to 9.0 or more.
5 . The method for producing mixed metal salts according to claim 1 , wherein, in the Al removal step, a solvent containing a carboxylic acid-based extracting agent is used to adjust an equilibrium pH to 4.0 to 5.0.
6 . The method for producing mixed metal salts according to claim 1 , wherein, in the Al removal step, at least 80% or more of the manganese ions in the acidic solution and at least 80% or more of at least one of the cobalt ions and the nickel ions, on a mass basis, are left in an aqueous phase.