Application de la digestion acide sulfurique (H2SO4) à l'extraction du lithium à partir de la pegmatite à spodumène de Manono (RDC)

In this article we examine the sulfuric acid (H2SO4) digestion's results followed by water leaching in the lithium extraction from Manono's spodumene pegmatite (DRC). A pretreatment has been developed allowing the transformation of a-spodumene into less dense, more brittle and more reactive ß-spodumene. The analysis of spodumene by ICP-MS and ED-XRF showed that our sample consists mainly of oxides of Li, Si, Al and K with an average UO2 content of 3.5%. And binocular microscopy examination revealed the presence of spodumene as the main mineral species associated with quartz, lepidolite and muscovite. The reaction's temperature (175, 200, 250 and 300°C) was studied for the digestion of calcined spodumene at temperatures ranging between 750 and 900°C. For each temperature, the reaction time (30, 60, 120 and 180 minutes) and the ore/acid ratio (1: 1, 5: 4, 3: 2 and 7: 4) were considered. A Taguchi approach was used to optimize the conditions and the experimental variables. And the MINITAB software was used for this purpose. The experimental conditions show that the degree of lithium extraction during sulfuric acid (H2SO4) digestion is significantly influenced by the ore/acid ratio, the temperature and reaction time. The results show that 90% of lithium in the sample calcined at 900°C was extracted with an ore/acid ratio of 3: 2, a reaction temperature of 250°C and a reaction time of 180 minutes.