(1. 中國(guó)科學(xué)院 過(guò)程工程研究所 濕法冶金清潔生產(chǎn)技術(shù)國(guó)家工程實(shí)驗(yàn)室，北京 100190；
2. 中國(guó)科學(xué)院 綠色過(guò)程與工程重點(diǎn)實(shí)驗(yàn)室，北京 100190)
摘 要: 不銹鋼表面處理常采用稀硫酸溶液預(yù)洗滌，洗滌過(guò)程產(chǎn)生大量含鐵及其他微量元素的廢酸。實(shí)際生產(chǎn)中廢酸多采用中和方法進(jìn)行處理，試劑耗量大，產(chǎn)生大量廢渣，污染環(huán)境。針對(duì)典型不銹鋼硫酸預(yù)洗滌過(guò)程中產(chǎn)生的廢酸，研究廢酸體系中草酸絡(luò)合沉淀Fe(II)、常見微量金屬Cr(III)、Ni(II)以及Mn(II)的行為，并探討沉淀去除金屬離子后廢酸的循環(huán)利用。結(jié)果表明：隨著廢酸溶液中酸度的增高，金屬沉淀率降低，但在起始H2SO4濃度＜200 g/L、x(H2C2O4):x(Fe(II))摩爾比為1:1下，F(xiàn)e(II)的沉淀率仍達(dá)80%以上；金屬離子的沉淀順序?yàn)椋篘i(II)＞Fe(II)＞Mn(II)＞＞Cr(III)；金屬離子沉淀后廢酸溶液中酸度得到有效恢復(fù)，經(jīng)x(H2C2O4):x(Fe(II))＞0.75:1處理后的廢酸對(duì)不銹鋼表面氧化層具有較好的洗滌效果，實(shí)現(xiàn)了不銹鋼洗滌廢酸的再生循環(huán)利用。
關(guān)鍵字: 不銹鋼洗滌；硫酸廢酸；草酸；沉淀法；循環(huán)利用
（1. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100910, China;
2. Key Laboratory of Green Process and Engineering, Chinese Academy of Sciences, Beijing 100910, China）
Abstract:Sulfuric acid solution was commonly used for the surface pre-washing in the process of stainless steel treatment to remove the metal oxide layer. Large amounts of waste acid solutions containing high concentrations of iron and low concentrations of other metals were discharged in the process. Neutralization method was widely used in industrial practices, resulting in high reagent consumption, large amounts of solid waste discharge and serious environmental pollution. With respect to the typical waste sulfuric acid solutions, the complex precipitation behaviors of Fe(II) and some commonly found trace metals, such as Cr(III)、Ni(II) and Mn(II), with oxalic acid were investigated. The recycling of acid solutions after metal removal was also discussed. The results show that the metal precipitation decreases with the increase of the acid concentration. As the initial acid concentration is less than 200 g/L, the precipitation of Fe(II) still reaches more than 80%. The metal precipitation order is: Ni(II)＞Fe(II)＞Mn(II)＞＞Cr(III). After metal removal by precipitation, the acid concentration in the solution increases, restoring the pre-washing effectiveness. The waste acid solutions are treated using H2C2O4:Fe (II) molar ratio higher than 0.75:1, good pre-washing effectiveness can be achieved. Therefore, the waste acid can be well recycled after metal precipitation using oxalic acid.
Key words: stainless steel washing; waste sulfuric acid; oxalic acid; precipitation; recycling
