Lithium extraction from clays and micas in the DAP well

Abstract

The DAP well is a project by the TU Delft to be able to provide heat to a part of Delft. However, presently the geothermal well is not economically feasible. The well could be a potential source of lithium, which is mostly used in batteries. The demand for lithium is estimated to rise, thus this could potentially be a promising investment. In this research, the feasibility of extracting lithium from the clay and mica faces of the Delft Sandstone is estimated. The Delft Sandstone was formed in the Valanginian era and consists of sandstone and siltstone with clay interfaces. Potential minerals that could occur in this layer that can contain lithium are smectites, kaolinites, micas and illites, fibrous clays or chlorites. These minerals either contain lithium in their naturally occurring mineral structure or can be formed when in a mineral an element is substituted by lithium. The minerals that will be analysed in this research are hectorite, montmorillonite, bentonite, kaolinite, lepidolite, zinnwaldite, illite, sepiolite, palygorskite and cookeite.
The samples will be analysed and interpreted using Gamma-Ray Spectroscopy and Infrared spectroscopy. Gamma Ray Spectroscopy detects the naturally occurring gamma rays emitted from a rock sample. These are quantified in a general signal as well as concentrations of Potassium, Thorium and Uranium. High clay content will relate to a high K value thus a high GR (Gamma Ray) signal. In IR (Infrared) Spectroscopy a beam of infrared light is passed through a sample, which leads to the absorption of specific wavelengths by the molecular bonds present. These spectra are then compared to library spectra and minerals can be identified. In this thesis, the GR signal could not be related to the well logs as the sample quantity was too low. From the IR Spectra kaolinite and illite were defined in this layer. These clays can contain lithium when elements are substituted in their molecular structure.