【摘要】 对Ni(Ⅱ)-Co(Ⅱ)-C2O4-H2O体系镍、钴溶解度[M]T(M指金属离子)和过饱和度(S)进行了热力学分析,绘制出pH-lg[M]T图和pH-lgS图。结果表明:当2<pH<3时,镍、钴的溶解度最小;当pH<2时,镍、钴的过饱和度均随pH的上升而增大,此后继续提高pH值,其过饱和度基本保持恒定。加料方式也对镍、钴过饱和度和体系平衡pH值影响显著,正加(沉淀剂加入金属剂)过程的过饱和度和pH值均波动较小,反加(金属剂加入沉淀剂)过程则变化很大。共沉淀试验结果进一步证实了热力学分析。pH≈1时,共沉淀粉体呈现2种形貌,粒度分布较广;当pH≥2时,共沉淀粉体粒度均匀,形貌单一。采用正加的加料方式,更有利于得到粒度均匀、形貌单一的镍钴草酸盐共沉淀粉体。更多还原

【Abstract】 Thermodynamic analysis on the solubility [M]T(M represents metal ions) and supersaturation(S) of nickel and cobalt in Ni(Ⅱ)-Co(Ⅱ)-C2O4-H2O system was carried out.The relations between pH and [M]T or S were established consequently.The results show that the solubilities of nickel and cobalt are the lowest in the pH range of 2-3.The supersaturations of nickel and cobalt increased with increasing the pH value when the pH value was less than 2,and then remained stable when pH value was greater than 2.It is indicated that the supersaturation and pH value are steady for a precipitant-to-metallic mode,and are unsteady for a metallic-to-precipitant mode.The experimental results of the co-precipitation of Ni and Co confirmed the corresponding thermodynamic calculation.The particles with two distinct morphologies with a bimodal size distribution could be obtained at pH≈1,and mono-dispersed particles with a narrow size distribution could be obtained at pH≥2.The precipitant-to-metallic feeding mode was favorable to prepare the homogenous Ni-Co oxalate precursor powder.更多还原