Method for manufacturing aqueous slurry and method for manufacturing powderous hydroxide therefrom

A method for manufacturing an aqueous slurry comprising hydroxide or oxyhydroxide particles of one or more elements, wherein the one or more elements include at least one of Ni, Co and Mn, wherein the method comprises:

• supplying a flow of an aqueous metal salt solution comprising the one or more elements to a reactor vessel during a time period (T1-T2), having a beginning (T1) and an end (T2),
• during the time period (T1-T2), mixing the metal salt solution with an aqueous solution comprising one or more alkali hydroxides, thereby forming the aqueous slurry comprising the hydroxide or oxyhydroxide particles of the one or more elements,
• wherein the metal salt solution is supplied with a flow rate expressed as a volume per unit of time, wherein the metal salt solution has a concentration of the one or more elements expressed as mol. per unit of volume, and wherein the mathematical product of the flow rate and the concentration increases continuously during the time period (T1-T2).