Revisiting the Traditional Process of Spodumene Conversion and Impact on Lithium Extraction

Abstract

Since 1950, the traditional process has been dominating the production of lithiumLithiumcompounds from spodumeneSpodumeneores to sustain the lithiumLithiummarket because of its economic viability and the markets need for technical grade (99.5% purity) product. This traditional process includes thermal conversion, acid roasting and lithiumLithiumleachingLeaching. However, this process has not been challenged and very few studies have tried to explain its limitation (95% lithiumLithiumyield) or optimize the thermal treatment. Here, α to β spodumeneSpodumeneconversion and lithiumLithiumextractionExtractionwere performed in a rotary kiln on a 2 mm to 2 cm spodumeneSpodumeneconcentrate instead of a micrometric one using a 1050 °C, 30 min conversion treatment and 250 °C, 30 min, 30% H2SO4 excess leachingLeachingtreatment. X-Ray Diffraction analyses were performed on the converted material to determine the conversion rate by Rietveld analysis. It was observed after thermal treatment that the α-spodumeneSpodumeneparticles fractured and divided while the impurities remained compact. A sifting was performed after thermal treatment and it was determined that 65% of the initial mass became finer than 180 µm. X-Ray diffraction analyses and lithiumLithiumcontent measurement were performed on both fractions and it was determined that the finer fraction had a very high lithiumLithiumcontent of 3.24 wt%. LithiumLithiumextractions were performed on both fractions separately. While the coarser fraction’s lithiumLithiumyield was only 61% the finer fraction’s lithiumLithiumyield went up to 99% without any additional treatment. These observations may open more economical ways for the traditional process by potentially bypassing two third of costly steps such as grinding.