| 摘要 |
<p>1418060 Separating platinum group metal mixtures. SWARSAB MINING EXPLORATION & DEVELOPMENT CO (PTY) Ltd 27 July 1973 [10 Aug 1972] 35945/73 Heading C7D Platinum group metals containing Rh and/or Ir and optionally gold are, (1) fused with a flux (e.g. Na 2 CO 3 with optional additions of a melting point depressant such as borax or fluorspar), a lead compound (e.g. oxide sulphide, acetate formate, carbonate or sulphate) and optionally a reductant (e.g. carbon or charcoal) to form a lead containing alloy from which the slag is removed; (2) the alloy is leached with HNO 3 to remove Pb; (3) the residue is leached with aqua regia to remove Pt, Pd, Au (if present) and some Rh; (4) the leach solution from (3) is evaporated to dryness and the deposit roasted at 575-625‹C to render the Rh aqua regia insoluble; (5) the roasted residue is leached with aqua regia to remove Pt, Pd and any Au present, the residue being combined with the solid residue from (3) as a feed for a separation process. Prior to (1) a sludge may be leached in aqua regia, the residue going to (1) directly and the solution being treated with sodium bromate and sodium carbonate to precipitate Pt from the other platinum group metals and Au, the precipitate being included in (1). The solution from (3) may be treated with H 2 SO 4 to remove Pb and any platinum group metals dissolved in (2) may be precipitated by addition of formic acid.</p> |
