Knowing the metal content of electronic waste is essential to evaluate metal recovery. Lack of a standard method for digestion of precious metals from electronic waste has resulted in difficulty in comparison to the efficiency of recovery. In this study, different precious metal digestion methods and economic value of precious metals from different types of waste printed circuit boards in different fraction sizes, including computer printed circuit boards, mobile phone printed circuit boards, television printed circuit boards, fax machine printed circuit boards, copy machine printed circuit boards, and central processing unit were examined. The optimal digestion method using aqua regia, hydrogen peroxide, hydrofluoric acid, and boric acid was adopted. The precious metal content was analyzed to answer what precious metals and types of printed circuit boards is preference. The results presented the following order of total value of precious metals (\(\sum {W_{ti} \Pr_{ti} }\)): central processing unit > Mobile phone > Copy > Fax > Computer > Television. Among the precious metals, gold and palladium were, respectively, attributed to the highest value distribution. The average values of the precious (gold and palladium) and all of the metals of electronic waste are about 19 and 21 times higher than the average cost of the world’s top ten mines.

了解电子废物中的金属含量对于评估金属回收率至关重要。与回收效率相比，缺乏从电子废物中消化贵金属的标准方法导致了困难。在这项研究中，从不同类型的废料印刷电路板以不同的馏分尺寸，包括计算机印刷电路板，手机印刷电路板，电视印刷电路板，传真机印刷电路板，对贵金属进行了不同的消化方法和贵金属的经济价值，复印机印刷电路板和中央处理器。采用王水，过氧化氢，氢氟酸和硼酸的最佳消化方法。分析贵金属含量以回答首选哪种贵金属和印刷电路板类型。结果显示贵金属总价值按以下顺序排列（\（\ sum {W_ {ti} \ Pr_ {ti}} \））：中央处理器>手机>复印>传真>计算机>电视。在贵金属中，金和钯分别归因于最高的价值分布。贵金属（金和钯）和所有电子废物金属的平均值分别比世界十大矿山的平均成本高19到21倍。