(中南大學(xué) 冶金科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 針對草酸鹽配位共沉淀−熱分解還原法制備超細(xì)鐵鎳合金粉過程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O體系的溶液平衡建立熱力學(xué)分析模型，并根據(jù)模型進(jìn)行相關(guān)計算，揭示反應(yīng)體系中各物質(zhì)隨pH值、氨及草酸濃度的變化關(guān)系。結(jié)果表明：溶液中的Fe主要以[Fe(C2O4)n]2−2n絡(luò)合物形式存在，而鐵氨絡(luò)合物含量很低。當(dāng)氨含量較低時，溶液中的Ni主要以[Ni(C2O4)n]2−2n存在；氨含量較高時，在酸性條件下，溶液中的Ni主要以[Ni(C2O4)n]2−2n存在，在堿性條件下，則主要以[Ni(NH3)n]2+存在。低pH值下，Ni的沉淀率較Fe的高，而高pH值下，Ni的沉淀率則較Fe的低。
關(guān)鍵字: 鐵鎳合金；溶液平衡；絡(luò)合；氨；草酸；pH值
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The thermodynamics model of the precipitation-coordination equilibrium in Fe2+-Ni2+-NH3-NH4+-C2O42−-H2O system was established and the calculation of the model was carried out. The relationships of each substance in solution with pH value, ammonia and oxide acid were revealed. The results show that, Fe in solution exists as [Fe(C2O4)n]2−2n mainly in contrast to low content of [Fe(NH3)n]2+. At low ammonia content, Ni in solution exist as [Ni(C2O4)n]2−2n mainly. At high ammonia contents, Ni in solution exists as [Ni(C2O4)n]2−2n and [Ni(NH3)n]2+ under acidic and alkaline conditions, respectively. The precipitation rate of Ni is higher than that of Fe at low pH value, and lower than that of Fe at high pH value.
Key words: Fe-Ni alloy; solution equilibrium; coordination; ammonia; oxide acid; pH value
