Case Study 1: COOL+ Process for Primary Sources (Li) Exploitation

 

Case Study 1 is about the optimisation and demonstration of the COOL+ process for the recovery of lithium (Li) from lithium-containing raw materials such as spodumene. The core of the COOL+ process is the leaching of the ore with supercritical CO₂. To improve mobilisation rates, the material is thermally treated prior to leaching to convert the lithium-containing phases into α-spodumene. This facilitates mobilisation.

Leaching with CO₂ has the advantage that it is very selective. Thus, almost exclusively lithium is mobilised in the form of lithium hydrogen carbonate. To isolate the target product lithium carbonate, only a concentration by electrodialysis and subsequent precipitation by raising the temperature is required. As a result, battery-grade lithium carbonate is obtained directly without the addition of chemicals and without additional purification steps.

Since the lithium content in the ores is very low and is accompanied by a large proportion of gangue material, the processing of this gangue material is essential to create an economically and ecologically sensible process. In the COOL+ process, this is done by producing geopolymers, which are CO₂-free building materials. In this way, the stockpiling of the material and the associated costs and risks are avoided. On the other hand, new building materials are generated that can be used in a variety of ways.

In the METALLICO project, the COOL+ process is first optimised on a laboratory scale by TU Bergakademie Freiberg and then transferred to a pilot plant (6 kg ore per day) by Fraunhofer Institute for Ceramic Technologies and Systems IKTS. Based on this, another pilot plant (1 t ore per day) will then be built by Idener.

 

Next steps

In the first seven months of the project, drill cores containing spodumene were mechanically processed and analysed by Lithium Iberia. In addition, the optimisation of the thermal pre-treatment as well as the CO₂ leaching were started. The first investigations showed that a concentration of the material by e.g. flotation is necessary to make the process economical. For this reason, the next steps relate in particular to this concentration.

Advantages of the process:

 

• Selective lithium recovery
• Applicable to a wide range of raw materials
• Material utilisation of CO2
• No use of chemicals
• Isolation of battery-grade lithium carbonate without purification steps
• Use of leaching residue for the production of geopolymers
• Complete recycling of the starting material, no waste
• The entire process can be run on electricity, so there is no need for fossil raw materials at all
• Simple water treatment