Commissioning of a mini REE SX pilot plant at SGS Minerals Services - Lakefield site

SGS Minerals Services commissioned an internal R&D program to develop in-house expertise in the design, setup, and operation of a REE separation pilot-plant at its Lakefield, Canada site. A mini pilot scale SX circuit of 120 stages was designed, constructed and operated to separate Pr and Nd from La and Ce contained in a synthetic REE chloride stream simulating the raffinate from an initial La-Nd|Sm-Lu+Y separation. Two pilot campaigns were run totalling 25 days of 24/7 operation with 99.4% plant availability in the final 20 day campaign. Purities of >99.9% in the PrNd strip liquor and >99% in the LaCe raffinate were achieved and simultaneously sustained for prolonged periods. Key to controlling and adjusting the circuit was the rapid assay turnaround (as low as 1-2 hours) provided by the on-site SGS analytical laboratory. This permitted the operating team to modify conditions and observe the effect of changes relatively quickly considering the large number of stages. A portable XRF analyser was also used to monitor progressive assay trends. A MS Excel-based model was developed to simulate the SX plant behaviour and allow future circuit design. This paper discusses the design of the circuit, operating conditions, some of the key operating factors and controls, and results obtained.