不锈钢老化着色液预还原草酸沉淀除杂过程研究

为实现不锈钢老化着色液杂质离子的分离与回收，采用预还原-草酸沉淀法对老化液中铁、镍、锰沉淀除杂过程进行研究。通过溶液化学计算及条件优化实验，考察铁、镍、锰离子沉淀效率，并使用X射线衍射仪、扫描电子显微镜、X射线光电子能谱仪对草酸沉淀物进行物相及形貌结构的表征。结果表明，通过控制溶液pH及草酸用量可有效实现溶液中铁离子、锰离子、镍离子与草酸根络合，形成草酸盐沉淀，实现杂质离子与溶液铬离子分离，杂质离子沉淀顺序依次为锰离子、镍离子、铁离子。老化液预还原后，在草酸过量系数为1.2、溶液pH为2、反应温度为25℃的条件下沉淀反应2 h，铁、锰、镍离子沉淀率分别可达98.12%、99.35%、87.26%，沉淀物主要为二水草酸亚铁及少量草酸镍、草酸锰。

Study on impurity removal process of prereduction-oxalic acid precipitation in stainless steel coloring ageing liquid

In order to realize the separation and recovery of impurity ions in stainless steel aging coloring liquid，the impurity removal process of iron，nickel and manganese in aging liquid was studied by a prereduction-oxalic acid precipitation method.The precipitation efficiency of iron，nickel and manganese ions was investigated by the solution chemistry calculation and condition optimization test.The morphology feature and phase structure of oxalate precipitate were analyzed by X-ray diffraction，scanning electron microscope and energy spectrum analysis，respectively.The results showed that Fe²⁺，Mn²⁺，Ni²⁺ in the solution could readily complex with C₂O₄^2- to form oxalate precipitate by controlling the solution pH and the oxalic acid dosage，which would realize the separation with Cr³⁺.The precipitation order of impurity ions was Mn²⁺，Ni²⁺，Fe²⁺.After prereduction of the aging solution，the precipitation reaction was carried out for 2 h under the conditions that the oxalic acid excess coefficient was 1.2，the solution pH was 2，and the reaction temperature was 25 ℃.The precipitation efficiency of iron，manganese and nickel ions could reach 98.12%，99.35% and 87.26%，respectively.The precipitate was mainly composed of ferrous oxalate dihydrate，a small amount of nickel oxalate and manganese oxalate.