Researchers develop a new way to extract lithium from rocks

The key chemical in the process is ammonium fluoride (NH₄F). It is possible to use the salt in solution, but heating it always creates hydrogen fluoride, which is very dangerous (although it can be used later). Therefore, instead, they used water-soluble, which prevents this from happening. In this process, heating the solution to about 70°C results in the formation of NH₄F₂ ions, producing ammonia gas which is used later.

This ion donates fluorine to the lithium, leaving an aqueous solution of lithium fluoride. Silicon also forms a soluble ion, (NH₄)₂SiF₆), while aluminum forms a similar ion that remains behind as a solid, (NH₄)₃AlF₆). Each of these is prepared separately.

Using everything

We will start with the chemistry of aluminum, which is one of the simpler methods. Initially, the temperature of (NH₄)₃AlF₆ up to about 300°C it forms aluminum trifluoride and emits ammonia and hydrogen fluoride. Then, raising the temperature to 700°C causes aluminum trifluoride to react with water, leaving aluminum oxide and releasing hydrogen fluoride.

Again, hydrogen fluoride is a dangerous substance and must be handled with care. But it is easy to react with ammonia (which is produced at two different times here) and replace the ammonium fluoride that was used to start the whole process. So, aside from small losses due to inadequacy, the process also creates one of the most important things. At the moment, aluminum oxide is one of the most important raw materials for the production of scrap metal, and it can be fed into this, because the purity of the final products here was more than 98 percent.

We’ll just note here that it’s probably the worst part of the whole process, given the energy required for this heat and the toxic chemicals involved.

In contrast, silicon purification is a walk in the park. Simply adding ammonia to the solution formed the primary product (NH₄)₂SiF₆) react with water, releasing silicon dioxide and ammonium fluoride. Again, ammonium fluoride solution is one of the starting materials; Silicon dioxide is released in this process. It has a variety of uses, but the group showed that it is very effective in strengthening concrete.