| The rapid and efficient dissolution of metallic Rh or Rh-base alloy scraps was recognized as a difficult technical problem in the circle of platinum group metals. Generally, the methods to dissolve these scraps include the high-temperature chlorination, fragmentation through alloying with Al, and melting with NaHSO4，which possess a series of disadvantages, such as lower dissolution percentage (usually, less than 30% for one time dissolution), longer period, serious environmental pollution and larger consumption of energy and chemicals. The special crystal structure, which is chemical inert, on the surface of metals and some kinds of inert oxides formed on the surface may be the seasons for the difficult dissolution of crude Rh or Rh-base alloy scraps. A new process for rapid and efficient dissolution of crude rhodium was introduced in this paper. It consists of ① changing chemical reaction activation of precious metals by smelting matte and activated metals; ② separating base metals through acid dissolution and then filtration; ③ dissolving of Rh by directly addition of solid oxidants in HCl solution. The Rh dissolution percentage of more then 99% for one time dissolution could be reached in 24~48 hours. The concentration of Rh in the solution of base metals was less than 0.0005 g/L. This method is note for its rapid and efficient, more simples, less consumption of energy and chemical reagents and friendly environment. The recovery ratio of Rh for the whole process was >99%. |
