Finland-based lithium producer Keliber has completed a four-phase pilot-scale test program and verified the behavior of the ore from the company’s largest deposit, Rapasaari, at all stages of the production process. A similar pilot-scale test program has previously been carried out using ore from Syväjärvi, the mine where quarrying will start first.
In the final phase of the test program, battery-grade lithium hydroxide monohydrate was produced from spodumene concentrate that had been treated in a high-temperature conversion in a rotary kiln. The hydrometallurgical technology, developed by Metso Outotec together with Keliber, includes soda pressure leaching and other process parts.
The pilot trial was conducted at Metso Outotec’s demonstration plant, located in Pori. The continuous pilot trial lasted 400 hours, and a total lithium recovery rate of more than 88% was achieved. It is a better result than what was estimated in Keliber’s Definite Feasibility Study published in March 2022.
Sami Heikkinen, Site Manager of Keliber’s Lithium Chemical Plant, states: “We are very pleased with the test program’s progress and with the results achieved in the pilot trials. We have now verified that we can produce battery-grade lithium hydroxide from not only the Syväjärvi ore but also by using ore from our largest deposit in Rapasaari.”
The test program started in the autumn of 2021. In the first phase, 130 tonnes of sample material from the Rapasaari deposit were drilled by percussion and diamond core methods. In the second phase, a continuous minerals processing test was performed at the GTK Mintec’s Pilot Plant in Outokumpu. The main stages of minerals processing are the crushing, grinding, classification, magnetic separation, flotation and dewatering.
Approximately 50 tonnes of Rapasaari spodumene ore were processed successfully during the pilot trial, resulting in 4 tonnes of spodumene concentrate.
In the third phase of the pilot, the alpha spodumene of the concentrate was converted to beta spodumene in a continuous high-temperature conversion process in a rotary kiln. The high-temperature conversion pilot achieved an average conversion rate of 96.3%. This phase of the test programme was conducted in collaboration with FLSmidth.