Abstract: This paper focuses on a novel extraction process for Au (Ⅲ).The original “magnetic-fluids fixed bed” (MFFB)，which bridges the solvent extraction and the fixed-bed extraction with the theory of the high gradient magnetic separation，is explained.The MFFB combines the advantages of the two classical extraction methods and overcomes their deficiencies.A novel method is proposed for the extraction of precious metal ions with low concentrations from aqueous solutions by using magnetic fluids in a high gradient magnetic separator (HGMS).Au (Ⅲ)was selected as the model species of precious metal ions.The feasibility of this method was tested by extraction experiments of Au (Ⅲ)from its aqueous solution.The extractant tributyl phosphate (TBP)was dissolved in the magnetic fluid and the extraction efficiency for Au (Ⅲ)was studied.The magnetic extractant containing magnetic fluid and TBP，as stationary phase in the form of liquid-droplet，was immobilized on the surface of steel wires in the HGMS.The low concentration Au (Ⅲ)，as mobile phase，flowed through the HGMS and was extracted from the aqueous solution.The influence factors such as the diameter of ferromagnetic wire，the pH of initial gold solution，the volume fraction of extraction solvent and co-extraction were investigated.The most effective factors for the experiment were obtained.With the wire diameter of 2.34 mm，initial pH of 1，and the volume fraction of 50%，the method gave high extraction efficiency in a continuous process.In addition，the co-extraction with triphenylphosphine oxide (TPPO)and TBP can improve the extraction rate. This method is especially suitable for the extraction of low concentration Au (Ⅲ)from aqueous solutions，which is very difficult to be recovered by traditional extraction technologies.The extraction process is continuous，which is suitable for practical industrial production.

Key words: magnetic fluid , high gradient magnetic separation , extraction of low concentration gold ions

摘要： 采用一种全新的快速萃取方法——磁性流体固定床萃取分离技术，该方法是将磁性Fe₃O₄纳米颗粒表面包覆油酸，溶于有机溶剂中，加入萃取剂三苯基氧化膦TPPO，制成磁性萃取剂。借助于高梯度磁性分离装置，对目标离子进行萃取分离。萃取完成后通过原子吸收光谱仪测定萃取后金溶液中Au³⁺的浓度。通过对铁磁导线直径、初始金溶液pH值、萃取剂体积分数和协同萃取等影响因素的考察，得出了对Au³⁺浓度为19.128 mg·L^-1的氯金酸溶液进行萃取分离的最佳工艺：采用直径为2.34 mm的铁磁导线作为磁性填充介质时萃取率较其他优越。初始金溶液的pH值和萃取剂的体积分数对萃取率影响较大。在初始金溶液pH=1，萃取剂(TPPO)体积分数达到50%时萃取率最高。使用TPPO和TBP协同萃取也能提高萃取率。采用浓度为1 mol·L^-1的硫脲进行反萃实验，振荡10 min，反萃率在90%以上。

关键词: 磁流体, 高梯度磁场分离, 低浓度金离子萃取