A novel laboratory procedure for predicting continuous centrifugal gravity concentration applications: The gravity release analysis

A novel procedure, Gravity Release Analysis (GRA), is introduced for performance prediction of continuous centrifugal concentration, using lab-scale batch tests. Also, linked with the GRA, the Gravity Release Index (GRI) was developed for ranking the ore amenability to centrifugal gravity concentration. Ore samples from the flotation circuit of Myra Falls concentrator were subjected to Multi Pass Test and Gravity Amenability Test for comparison with GRA. Recovery kinetics of batch centrifugal concentration was analysed to establish the Gravity Release Index (GRI). Both Gravity Amenability Test and Multi Pass Test failed to cover the broader mass yield range of continuous centrifugal concentration and this was the main drawback in performance prediction of larger units from lab-scale data. GRA covered a wider mass yield range, yielding better performance prediction of larger continuous units. From the gravity recovery kinetics of the batch unit, varying GRI values for Au, Fe, Zn, Fe and S were obtained, with Au having the highest- GRI and amenability to centrifugal gravity concentration. Varying amenabilities for different Au forms (free Au particles, Au bearing sulphides) to centrifugal gravity concentration could also be distinguished. SEM analysis on recovered gold entities justified the prediction by the GRI. Overall, GRA could effectively predict continuous centrifugal concentration using small amounts of feed with lab-scale batch units. Determination of the GRI for targeted metals would provide further precision for bench-marking and scaling-up of continuous centrifugal concentration.