EVALUATION OF FLOTATION PERFORMANCE USING VARIANCE SPECTRUM ANALYSIS

The performance of Denver sub-A flotation cells in rougher and 1st cle aner service in Inco's Matte Separation plant was studied using the te chnique of Variance Spectrum Analysis. The procedure involves fitting a Fourier Series to real-time plant data and filtering out the low fre quency disturbances on the assumption that performance would be enhanc ed with improved equipment installation - in this case Denver DR flota tion cells. The resulting series is then recalculated to estimate the response of the process under improved control. In the case under stud y, recovery of nickel to the high grade nickel sulfide product was pro jected to increase by 5% as a result of implementing the equipment upg rade in the rougher circuit. In addition, it was projected that the qu ality specification target of a secondary nickel sulfide product could be met simultaneously with that of the copper sulfide product, by upg rading the 1st cleaner cells. These targets had previously been diffic ult to achieve concurrently due to the strong inverse correlation betw een them. Based on this study an equipment upgrade was carried out. Su bsequent operation of both circuits confirmed the projected results an d the validity of the methods as basis for justifying capital investme nt based on improved metallurgical performance.