Method for preparing nickel sulfate using low-nickel ferronickel

A method for preparing nickel sulfate using ferronickel, comprising the following steps:

• (1) grinding ferronickel to obtain ferronickel powder, and then sintering the ferronickel powder in the presence of an oxidant to prepare ferronickel oxide powder;
• (2) adding sulfuric acid to the ferronickel oxide powder prepared in step (1), mixing, heating, and washing with water to prepare a sulfate water wash liquid;
• (3) adding alkali to the sulfate water wash liquid prepared in step (2) to adjust the pH value, then adding fluoride salt to form a precipitate, performing filtration to remove the precipitate, and drying the filtrate to obtain nickel sulfate;
• wherein in step (3), before drying the filtrate, an extractant is added to perform extraction to obtain a raffinate phase and a nickel-loaded organic phase, and then the nickel-loaded organic phase is back-extracted by sulfuric acid to obtain nickel sulfate;
• the extractant comprises sodium dodecyl sulfate, bis(2,4,4-trimethylpentyl) dithiophosphonic acid, tributyl phosphate, and sulfonated kerosene;
• a volume ratio of sodium dodecyl sulfate, bis(2,4,4-trimethylpentyl) dithiophosphonic acid, tributyl phosphate, and sulfonated kerosene is (1-10):(5-20):(1-10):(60-90).