Abstract: Nanofiltration can be used to improve a hydrometallurgical process in which valuable metal is extracted from ore or tailings by leaching with a suitable lixiviant. The process requires at least two nanofiltration subsystems in which raffinate from a solvent extraction process is treated in a nanofiltration subsystem, after which permeate therefrom is combined with a pregnant solution stream and is treated in a second nanofiltration subsystem. This arrangement can lead to advantages in the amount of lixiviant recovered, in the raw materials required, in the effluent produced, in the size of plant, and in overall cost.

Abstract: Methods are disclosed for removing alkali metal iodide from concentrated aqueous alkali metal chloride solutions using ion retardation resins. The methods are suitable for solutions comprising substantially more than 1 ppm iodide and greater than 100 g/l alkali metal chloride and can remove the iodide to levels below 1 ppm. To effect removal, the pH of the solution is adjusted to be less than about 10 and is then flowed through a separation bed comprising the resin in a series of loading and elution cycles. The method is particularly useful for removing iodide impurity from the concentrated feed brine used in chloralkali electrolysis.

Abstract: Nanofiltration can be used to improve a hydrometallurgical process in which valuable metal is extracted from ore or tailings by leaching with a suitable lixiviant. The process requires at least two nanofiltration sub-systems in which raffinate from a solvent extraction process is treated in a nanofiltration subsystem, after which permeate therefrom is combined with a pregnant solution stream and is treated in a second nanofiltration sub-system. This arrangement can lead to advantages in the amount of lixiviant recovered, in the raw materials required, in the effluent produced, in the size of plant, and in overall cost.

Abstract: Nanofiltration membranes have been identified that can unexpectedly provide for competitive removal of silica and sulfate from brine in alkaline conditions. Such membranes are known as monolithic nanofiltration membranes and are particularly suitable for removing silica and sulfate impurities from a brine stream in a brine electrolysis plant.