研究論文
シリコン粉末への無電解置換析出を利用した貴金属回収
－添加剤や酸化溶出物のないクリーンプロセス－
2018 年 69 巻 2 号 p. 86-89
詳細
2018 年 69 巻 2 号 p. 86-89
Recovery of noble metals from scrap electronics （urban mines） and industrial waste including plating solutions has attracted keen attention for cost reduction and natural resource conservation. Cementation, the displacement deposition of metals onto less noble metals, is a common method for recovering dissolved noble metals from aqueous solutions. We recently developed a method of recovering noble metals by adding silicon powder and hydrofluoric acid to an aqueous solution. This method presents benefits of process simplicity, noble metal selectivity, and usability under the presence of oxidizing agent such as aqua regia. Unfortunately, it uses toxic hydrofluoric acid. For this study, a noble metal recovery method was developed using bare silicon powder with no hydrofluoric acid. Bare silicon powder was obtained by etching of a silicon oxide layer on commercial silicon powder using a hydrofluoric acid or sodium hydroxide solution. Results show that noble metals of eight kinds are recoverable using bare silicon powder. This method presents the three important benefits of the previous method in addition to two more benefits of obviating toxic hydrofluoric acid and leaving no additional product such as hexafluorosilicate into the solution. Consequently, this can be regarded as a clean process that is effective for recycling solutions such as electrolytes by removal of noble metal species.
