Selective precipitation of dissolved minerals of geothermal brines
Supervisors: Prof. Dr. Thomas Kohl, Dr. Fabian Nitschke (both KIT), Prof. Dr. Diego Morata (UCHILE)
Person in charge: Valentin Goldberg
The Ph.D. study takes place in the German-Chilean project BrineMine which follows the approach of extracting raw materials and drinking water from geothermal brines in an ecologically friendly way.
Beyond their potential in energy production, thermal waters can contain significant quantities of valuable elements as lithium, rubidium, or antimony. These elements are of great importance for the energy sector and the high-tech-industry and further are classified as critical raw materials. In the past years, the salt lakes in the Atacama Desert in Chile have received high interest as an important resource for lithium. The mining in this area is accompanied by a large environmental impact as well as high water consumption. In the driest desert on earth, thus a high potential for conflicts is arising.
Within the project, the heat of the water shall power a technical process, which separates the mineral raw materials, and the water in a closed-loop using membrane technology. The aim is to extract not only the minerals but also drinking water as an important resource. Compared to conventional evaporation processes, the membrane processes accelerate the concentration of minerals in the waters, so that a resource-efficient and sustainable alternative to conventional Li mining is demonstrated.
The Ph.D. study focuses on the geochemical accompaniment of the project. One focus here is on the pretreatment of saline waters to prevent mineral precipitation within the membrane modules. Uncontrolled precipitation of silicates, which are often close to saturation in geothermal waters, can limit the productivity of the plant. Targeted precipitation ensures the processability of the fluid and further offers the opportunity to produce the silicate itself as a raw material. In parallel, a geochemical exploration campaign in northern Chile is organized and will be conducted to estimate the raw material potential of geothermal waters and to select an ideal site for extracting raw materials.
