湿式素材プロセッシング

[2P0105-05-01] 金精練における有機王水によるアマルガム法の代替 (発表者：学士課程)

○ABDUL JALIL¹、吉村 彰大¹、松野 泰也¹ (1. 千葉大学)

キーワード：小規模金採掘、金溶解、ジメチルスルホキシド、塩化銅（Ⅱ）、沈殿

In present, about 1/4 of world gold supply is produced by the artisanal small-scale gold mining (ASGM) process. This process consumes large amounts of mercury for the amalgamation of gold, and release mercury to soil, air and water. This release causes environmental pollution and health hazard. To avoid these problems and risks, in this experiment we applied the "Organic Aqua Regia" (OAR) to the gold refining as the replacement for amalgamation. This OAR consists of DMSO containing CuBr₂ or CuCl₂ and can dissolve gold at high-speed. The dissolved gold can be recovered as pure gold particle by the addition of acidic water for the gold containing OAR, and the authors confirmed the recovery of gold from E-waste. In this experiment, the authors applied the OAR containing CuCl₂ and NaCl for the model ore and confirmed the gold dissolution and recovery of dissolved gold. The model ore was made of gold wire and sand, and the concentration of gold varied from 500 ppm to 1 %. Dissolved gold was precipitated by the addition of HCl. As the result, the gold dissolution from 500 ppm model ore by the OAR treatment and the precipitation of dissolved gold by the addition of HCl were confirmed. The dissolution rates were decreased by the decrease of the concentration of gold in the ore. In contrast, the recovery ratios were about 80% in all conditions and impurities like potassium or silicon from the sand were not detected from recovered gold. Through this experiment, the authors confirmed the availability of OAR process as the refining of gold from model ore.