Recovery of copper and cobalt by biopolymer gels.

The recovery of copper from synthetic aqueous media circulating in a loop fluidized bed reactor operated batchwise was investigated by using the following biopolymer systems: (1) a viscous solution of sodium alginate (from kelp) dispensed directly into the reactor fluid containing dissolved copper (sulfate salt) at initial concentrations of 60-200 ppm, (2) partially coagulated calcium alginate spheres for absorbing dissolved copper at initial concentrations of 10-40 ppm, and (3) a mixture of green algae Microcystis and sodium alginate dispensed directly into the reactor fluid. The recovery of copper and cobalt, a strategic metal, from cobalt ore leachate was achieved by a two-step approach: direct dispensing of sodium alginate to absorb the bulk of metals followed by the addition of partially coagulated calcium alginate spheres to "polish" the leachate. Metal binding capacity and conditional stability constant of each biopolymer system as well as the effective diffusivity of cupric ion in the matrix of biopolymer gels are reported.