关键词: 钢渣, 酸解, 多组分, pH值, 磷酸铁

Abstract: Dissolving steel slag in sulfuric acid and reacting the filtrate with phosphoric acid through adjusting pH value, a multi-metal-doped iron phosphate is prepared by recovery of multiple metals from steel slag. The precipitation behaviors of target metal ions, such as Fe, Mn, Cr, Al, Mg and Ti, existing in the reaction system with appearance of PO43- polyanion are discussed. The results indicate that the precursors precipitated at pH=3.0~4.0 exhibit amorphous particles of about 50 nm, with molar ratio of total metals to phosphorous nearly to 1. Roasted at 700℃ for 5 h in air, the precursors crystallize into homogeneous powder of about 200 nm, and are identified by XRD as single-phase multi-doped iron phosphate with a hexagonal structure. Further increase of pH value to 5.0 and 6.0 causes an excessive precipitation of nonferrous metal elements in the product, leading to a departure from stoichiometric ratio and presence of undesirable phases. The inexpensive metals-doped iron phosphate precursor for synthesis of lithium iron phosphate can be prepared from the steel slag.

Key words: steel slag, acidolysis, multi-component, pH value, iron phosphate