Dissolution of Lithium Contained in Lepidolite Using Ascorbic Acid: Kinetic and Modeling Analysis

Area of Science:

• Geochemistry
• Materials Science
• Chemical Kinetics

Background:

• Rock samples rich in lithium, particularly those containing lepidolite, are valuable resources.
• Understanding the decomposition kinetics of these minerals is crucial for efficient lithium extraction.
• Ascorbic acid offers a potential medium for mineral processing due to its chemical properties.

Purpose of the Study:

• To conduct a kinetic study and modeling of a lepidolite-rich rock sample's decomposition in ascorbic acid.
• To determine the kinetic parameters, including reaction order and activation energy, for the decomposition process.
• To elucidate the reaction mechanism and control regime governing the mineral decomposition.

Main Methods:

• Rock sample characterization using X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS).
• Kinetic analysis of lithium (Li) element decomposition curves in an ascorbic acid medium.
• Modeling of decomposition data to obtain kinetic parameters and expressions.

Main Results:

• The rock sample comprised 65.3% lepidolite, 30.6% quartz, and 4.1% muscovite, with a Li content of 3.38%.
• Kinetic analysis yielded a reaction order (n) of 0.4307 and activation energy (Ea) of 48.58 kJ mol⁻¹ for the induction period, and n = 0.309 and Ea = 25.161 kJ mol⁻¹ for the progressive conversion period.
• A mixed control regime was observed, transitioning from chemical to transport control at higher temperatures, with chemical control predominating.

Conclusions:

• The kinetic study successfully modeled the decomposition of the lepidolite-rich rock in ascorbic acid.
• The determined kinetic parameters provide insights into the reaction mechanism and control factors.
• The findings are significant for optimizing lithium extraction processes from lepidolite-containing ores.