THE MECHANISM OF INTERACTION BETWEEN ORE FINES AND POROUS ADSORBENTS

Activated carbon and ion exchange resins are being used extensively in the mining industry to extract metal cyanides from leached liquors. R ecently, ion exchange membranes and fibres have been investigated as p ossible alternatives to carbon and resin. This paper describes the int eraction between fine ore particles and porous adsorbents in a batch r eactor. Gold cyanide was used as an adsorbate to detect changes in the mass transfer characteristics of the adsorbents, These changes were e valuated using a film/surface diffusion model, with specific emphasis on the diffusion and equilibrium parameters. Tests involving the intru sion of ore particles into the adsorbents indicated that the adsorptio n profile for gold cyanide is affected only for activated carbon and i on exchange resins, These results were confirmed by ashing tests, scan ning electron microscopy and secondary ion mass spectrometry performed on the adsorbents, However, the diffusion of gold cyanide to all adso rbents was inhibited owing to the physical blinding of the superficial surface by the fine particles in suspension. This result was obtained by exposing a presaturated adsorbent to the suspended ore particles a nd dissolved gold cyanide. The effect of blinding was accounted for in the model with the introduction of an availability factor.