SYNTHESIS OF PT-SULFIDE AND PD-SULFIDE IN LOW-TEMPERATURE (85 DEGREES-C) SOLUTIONS BUFFERED BY CLAY-MINERALS AND GRAPHITE - PRELIMINARY-RESULTS

Some recent investigations of black shales reveal platinum-group eleme nt (PGE) concentrations in the ppm range. The low temperature nature o f these mineralized sediments and their composition stimulated this fi rst attempt to synthesize Pt- and Pd-phases in solutions at temperatur es below 100 degrees C under reducing conditions with H2S flow through the solution. Experiments under controlled Eh-pH with montmorillonite presaturated in Pd and Pt in different chloride solutions resulted in the formation of Pt- and Pd-sulphides. PtS- and PdS-stability fields are very close to each other in Eh-pH values (similar to 400 mV, 9). T hese data are in good agreement with those determined for some base me tal sulphides synthesized at similar temperature by other researchers. The results may support the role of clay minerals as possible concent rators for PGE in the sedimentary environment.