NEW SYNERGISTIC SOLVENT EXTRACTION SYSTEMS FOR SEPARATION AND RECOVERY OF NICKEL, COBALT, COPPER AND ZINC IN SULPHURIC ACID, NITRIC ACID AND HYDROCHLORIC ACID LEACH SOLUTIONS

摘要

One step direct solvent extraction (DSX) for separation of nickel and cobalt from nickel laterite leach solutions provides an attractive path for producing high value nickel and cobalt products without need for producing intermediate mixed sulphide precipitation (MSP) and mixed hydroxide precipitation (MHP) products. CSIRO solvent extraction (SX) researchers previously developed several SX and synergistic solvent extraction (SSX) systems. In the present work, a new synergistic solvent extraction (SSX) system has been discovered and DSX processes employing the new SSX system developed for extraction and separation of nickel, cobalt, copper and zinc from manganese, magnesium and calcium in sulphuric acid, nitric acid and hydrochloric acid / high chloride leach solutions. The newly developed SSX system and the associated DSX processes exhibit desirable properties, including:- Organic composition employing two commercial extractants without need for a modifier,- Strong synergistic extraction and separation of nickel, cobalt, copper and zinc from manganese, magnesium and calcium impurities in various matrices (sulphate, nitrate, and chloride) in one DSX step, as well as separation of copper from Fe and Al,- Reversible extraction and stripping of all the metals,- Appropriate complex affinity difference to offer selective extraction or stripping to separate nickel, cobalt and zinc from copper within the SSX circuit,- Fast kinetics of metal extraction and stripping, suitable for commercial applications,- Ability to transfer the loaded valuable metals from nitrate and chloride matrices to sulphate via stripping to provide process options for separation and recovery of individual metal products in sulphate,- Chemical stability in various matrices (sulphate, nitrate, and chloride) and in corresponding sulphuric acid, nitric acid and hydrochloric acid solutions under extraction and stripping conditions, and good phase separation properties.