关键词: 磁流体, 高梯度磁场分离, 低浓度金离子萃取

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