Preparation of battery-grade iron phosphate from nitric acid pressure leaching residue of nickel laterite ore
In recent years,under the guidance of"carbon peaking"and"carbon neutrality"goals in China,the new energy industry is developing rapidly.The promotion and use of new energy vehicles have promoted the vigorous development of the lithium-ion battery industry.Nickel is a key raw material for ternary lithium-ion batteries,and its demand is increasing.Due to the depletion of nickel sulfide ores,laterite nickel ores have gradually become the main raw material for yielding nickel,accounting for more than 70％of nickel production.The limonitic laterite nickel ore accounts for more than 60％of the laterite nickel ore.The leach residue produced after the extraction of nickel and cobalt by nitric acid pressure leaching(NAPL)is rich in valuable metal resources(iron content＞60％).The comprehensive utilization of leach residue is of great significance to resource recovery and environmental protection.In this paper,the raw material is nitric acid pressure-leaching residue of limonitic laterite nickel ore,which was used to prepare battery-grade iron phosphate in a single phosphoric acid medium.The efficient extraction of iron from leach residue was realized by pre-leaching and dissolving with phosphoric acid as medium.The low concentration of phosphoric acid solution during pre-leaching allowed the initial transformation of the iron-containing phase to FePO4·2H2O,while Cr,Mg,Al and other impurity elements in leach residue were removed.Then,the pre-leaching residue was dissolved by phosphoric acid with high concentration,which achieved complete dissolution of Fe.Finally,the iron phosphate was directly precipitated by diluting and adjusting the pH values,and then the product of FePO4·2H2O was obtained.The product did not contain impurity elements such as Mg,Si,and the content of Cr and Al is only 0.019％and 0.016％,respectively.The phase composition and microstructure of pre-leaching residue and iron phosphate products were investigated by XRD,SEM and EDS.It is clarified that the pre-leaching process could realize the transformation from Fe2O3 to FePO4·2H2 O.The crystal structure of the final product matches the standard iron phosphate well.The lithium iron phosphate materials synthesized from iron phosphate also exhibited excellent electrochemical properties.This study is expected to achieve high-value utilization of macro component iron in the nitric acid pressurized leaching residue of brown iron type laterite nickel ore,thereby optimizing the preparation process of iron phosphate.
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维普
