Electrolytic dissolving of platinum@, platinum@ metal impurities and platinum@ metal alloys - using electrolytic cell with platinum metal salt or acid in the hydrochloric acid in the anode and cathode chambers of the cell

摘要

Platinum, platinum metal impurities and platinum metal alloys containing esp. Rh, Pd, Ir, An and Ag are connected as the anode in an electrolytic cell employing a teflon membrane as the cation exchange membrane and hydrochloric acid as the electrolyte. Platinum metal salt or acid is mixed with the acid and the cell is operated at 50-110 deg.C under a voltage of 2.5-8V and current density of 0.3-7.0 A/dm2. The anode and cathode chambers are filled with 6-8 N HCl and the voltage is chosen such that Cl2 gas is produced. The platinum anode is contacted with the platinum metal-containing acid and the Cl2 gas in a pulsed manner. The voltage is pref. 5-7.5 V and the current density 4.4-6.6 A/dm. The HCl concentration in the anode chamber is held constant with the volume loss of acid being constantly compensated for by Cl2 gas production. The dilute HCl is periodically withdrawn from the cathode chamber and the concentration increased by adding new acid. The pref. temp. is 60-100 deg.C. USE/ADVANTAGE - Dissolving platinum in the form of granules, sheet, turnings, wire, powder, etc. Operates where the HCl is at its highest conductivity. Process requires min. safety technology and apparatus expenditure. Any possible damage to the ecology is minimised.