Arrangement and method for air-induced evaporation and cooling

An arrangement for processing an aqueous metal-containing slurry, including the lines for recirculating at least a fraction of the liquid stream passing through the arrangement, which arrangement comprises:

• a pressure leaching unit for leaching the metal-containing slurry at an elevated pressure and elevated temperature, to provide a leached slurry,
• one or more flash vessels, wherein the pressure and temperature of the leached slurry conducted to the vessel(s) from the leaching unit are decreased, thus providing an atmospheric leach slurry,
• an atmospheric mixing reactor, with an air inlet and mixing gear, for dispersing air into the atmospheric leach slurry conducted to the reactor from the flash vessel(s), as well as for causing air-induced evaporation of a fraction of the water in the slurry and simultaneously cooling of the slurry, thus providing a concentrated slurry and a fraction of off-gas containing moist air,
• a solid-liquid-separation unit, for separating the solids of the concentrated slurry from the solution, and
• a recirculation line for carrying at least a fraction of the solution obtained from the solid-liquid separation unit back to the pressure leaching unit, optionally via one or more intermediate treatment units.