A study of the precipitation of platinum from dilute aqueous solution.
Washington, DC: U.S. Department of the Interior, Bureau of Mines, Contract G1125132-3209, 1984 Jan; :1-55
Hydrogen sulfide gas was used to precipitate platinum sulfide from a dilute aqueous platinum solution. The precipitation was carried out in a continuous mixed suspension, mixed product removal precipitator. The platinum sulfide precipitate formed a stable colloidal suspension. The average particle size was about 7 nm. The purpose of this research was to be able to control and predict the size distribution of particles formed during the platinum sulfide precipitation. A mathematical model based on a steady-state particle population balance that relates the particle size distribution to nucleation and growth kinetics and operating parameters was compared with experimental particle size distributions. The model did not predict the observed size distributions. A qualitative model based on the brownian motion of the particles and their electrostatic interactions is proposed to explain the observed size distributions. Addition of electrolytes to the colloidal suspension of platinum sulfide caused the particles to flocculate and form large, easily filtered particles. The higher the cation valence, the more effective it was as a flocculating agent. The problem with using electrolytes as flocculating agents is that the metal cations contaminate the flocculated platinum sulfide particles.
CP; Final Contract Report
OFR 64-86; Contract-G1125132-3209
Washington, DC: U.S. Department of the Interior, Bureau of Mines, Contract G1125132-3209
Iowa State University