表面技術
Online ISSN : 1884-3409
Print ISSN : 0915-1869
ISSN-L : 0915-1869
69 巻 , 5 号
選択された号の論文の6件中1~6を表示しています
小特集/表面微細加工とホログラム技術
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研究論文
  • 福田 健二, 有田 翔太郎, 津田 多公也, 松本 歩, 八重 真治
    2018 年 69 巻 5 号 p. 203-205
    発行日: 2018/05/01
    公開日: 2018/12/01
    ジャーナル フリー

    Recovery of noble metals from scrap electronics(urban mines)and industrial waste including plating solutions has attracted keen attention. We recently developed an efficient method of recovering noble metals through electroless displacement deposition onto silicon powder from acidic solutions. For this study, we applied this method to gold recovery from a basic solution. Commercially available silicon powder was added to a simple HAuCl4 aqueous solution with pH adjusted using HCl and NaOH. Gold was recovered only slightly from the solution with pH lower than 8, but the gold recovery continued and the recovery rate increased from a solution with pH higher than 9. In the low-pH solution, the silicon oxide layer inhibits displacement deposition of gold onto silicon powder. In the high-pH solution, as the silicon oxide layer dissolves, the local anodic reaction of silicon dissolution continues. Results show that the gold recovery rate increased with the amount of silicon powder and solution temperature. At solution pH of 13, gold of 0.001 mol dm-3 was 100% recovered by 30 min treatment with 0.5 mol dm-3 of silicon powder at 298 K. From a model leaching solution including Na3Au(SO32, CuSO4,(NH42S2O3, and NH4OH at pH of 9.3 and a waste of displacement gold plating solution including KAu(CN)2 at pH of 12.4, gold was recovered efficiently merely by addition of silicon powder. This method is anticipated as a simple, safe, and efficient gold recovery method.

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