Hydrometallurgical recovery method for nickel sulfate
The present disclosure relates to a hydrometallurgical recovery method for nickel sulfate. More specifically, the present disclosure relates to a hydrometallurgical nickel sulfate recovery method in which a wet smelting process is used to extract a high-purity nickel sulfate aqueous solution from a raw material containing nickel (Ni), cobalt (Co), and manganese (Mn). In the method, sodium hydroxide or sodium carbonate is not used as a neutralizer but nickel hydroxide is used, which prevents salts of impurities from being generated as a precipitate in a solvent extraction process, thereby increasing process efficiency of the solvent extraction process.
1 . A hydrometallurgical nickel sulfate recovery method comprising:
a washing step of washing a raw material containing nickel (Ni), cobalt (Co), and manganese (Mn) with washing water, wherein the raw material and the washing water are in a volume ratio in a range of 1:1 to 5 in the washing step;
a first solid-liquid separation step of separating the washed raw material into a raw material cake and a filtrate;
a first leaching step of adding sulfuric acid to the raw material cake for reaction, wherein in the first leaching step, an equivalent ratio of a metal in the raw material cake and the sulfuric acid is in a range of 1:0.5 to 2;
a second leaching step of adding hydrogen peroxide to a first leachate obtained through the first leaching step for reaction, wherein in the second leaching step, an equivalent ratio of metal components, including manganese and cobalt, in the first leachate to the hydrogen peroxide is in a range of 1:0.5 to 2;
an iron precipitation step of adding hydrogen peroxide and nickel hydroxide (Ni(OH) 2 ) to a leachate formed through the first and second leaching steps for iron precipitation, wherein in the iron precipitation step, an equivalent ratio of iron in the leachate to the hydrogen peroxide is in a range of 1:0.5 to 3;
a second solid-liquid separation step of separating reaction products of the iron precipitation step into a precipitate containing iron and a leachate containing nickel, cobalt, and manganese;
a solvent extraction step of extracting a nickel sulfate aqueous solution (NiSO 4 ) from the leachate; and
a nickel hydroxide preparation step of preparing nickel hydroxide (Ni(OH) 2 ) from nickel-bearing liquid waste obtained through the solvent extraction step,
wherein the nickel hydroxide prepared through the nickel hydroxide preparation step is used in the iron precipitation step.
2 . The method of claim 1 , wherein the raw material is a mixed hydroxide precipitate (MHP(OH) 2 ), a mixed carbonate precipitate (MCP, MeCO 3 ), a mixed sulfate precipitate (MSP, MeSO 4 ), or black powder (BP), and
Me is at least one of the Ni, the Co, or the Mn.
3 . The method of claim 1 , wherein in the iron precipitation, reaction is performed at a pH in a range of 3.5 to 6.5.
4 . The method of claim 1 , wherein the nickel hydroxide preparation step comprises:
a nickel hydroxide precipitation step of adding sodium hydroxide (NaOH) to the nickel-bearing liquid waste to precipitate the nickel hydroxide contained in the nickel-bearing liquid waste;
a third solid-liquid separation step of separating the reaction products generated in the nickel hydroxide precipitation step into a nickel hydroxide precipitate and the filtrate; and
a washing step of washing the nickel hydroxide precipitate with water to remove residual sodium.
5 . The method of claim 1 , wherein the solvent extraction step comprises:
a first solvent extraction step of separating manganese from the leachate; and
a second solvent extraction step of extracting the nickel sulfate aqueous solution (NiSO 4 ) by separating cobalt from the leachate from which the manganese is removed.