SND Consulting has designed a metallurgical testing program to optimize the parameters involved in lithium leaching, impurity removal, and lithium recovery.
TLC’s claystones have been tested for leaching in several ways, including:
The results show that the TLC claystones are highly leachable using sulfuric acid. In fact, one of the agitated leach tests shows that over 90% of the lithium can be leached within 10 minutes, which is much faster than comparable projects with leaching times on the order of hours or days.
Agitated Leach Test Results
|Leach Time [minutes]||Lithium Extraction [%]|
The acid cure test has shown great potential for maintaining high lithium extraction while minimizing acid use. American Lithium will continue to test leaching parameters to produce the highest extraction with the lowest inputs.
After leaching, the solution is at pH 1, and contains impurities such as iron, aluminum, magnesium, and calcium. First, the solution is heated to evaporate off excess water which results in the crystallization and subsequent removal of magnesium sulfate. After this, the solution is neutralized using locally sourced, low-cost limestone to removed iron and aluminum. The next treatment involves the addition of low-cost lime produced on site to precipitate out the remaining magnesium. Finally, low-cost soda ash is used to remove the calcium in the solution.
Results are shown in the flowsheet below. The tests show that the evaporation results in significant magnesium sulfate precipitation, and that neutralization results in the near complete removal of the iron and aluminum impurities. Magnesium is essentially completely removed by the addition of lime. The removal of calcium is the next test to be optimized.
After the impurity removal steps, and a final ‘clean-up’ using ion exchange (not shown in figure above), the solution is ready for lithium recovery.
The final products will be battery grade lithium carbonate (99.5%) and battery grade lithium hydroxide monohydrate (99%, 56.5% of which is LiOH).
American Lithium has begun the testing for producing these desired products and will publish results soon.
American Lithium intends to move towards the construction of a pilot plant in 2021 to prove the low-cost production of lithium compounds for the North American battery manufacturing market. Stay tuned for progress updates.