Impacto do lodo na eficiência da separação gravítica, um caso de estudo na mina de exploração de areias pesadas de Moma da Kenmare

Abstract

The present study aims to evaluate the impact of slimes on the efficiency of gravity separation in the wet concentration plant (WCP-A) of Kenmare Moma Mining and Processing (Mauritius) Ltd. For this study, wet samples containing slimes were collected from the Rougher spiral feed, dried, and divided into two parts. One part was washed to remove all slimes (with a content of 11.5%), while the other remained unwashed. Both samples underwent a separation process using a shaking table under the same operational parameters: table inclination, vibration intensity, and the same wash water volume. The gravity separation products (concentrate, middling, and tailings) were dried, divided into 200g portions, and subjected to separation using dense liquids (lithium heteropolytungstate), an intermediate-density liquid, to separate valuable minerals from gangue. The results showed that the presence of slimes reduced recovery by approximately 30%, yield by 10%, and quality by 20%. The sample was screened, and the cut size (d50) was determined to be 256 μm, indicating that particles of this size have a 50% chance of being recovered in either the concentrate or the tailings. Sedimentation was observed to be faster in WCP-B and WCP-C compared to WCP-A. It was concluded that slimes negatively affect recovery, yield, and quality. To mitigate this impact, it was recommended to improve feed preparation and install a desliming cyclone between the trommel and the surge bin.