Management of waste rock and tailings: a factor taken into consideration from the outset of the project.

Reducing the volume of concentration tailings at the source 

Mine tailings are the products made up of soil and rock excavated during the operation of a mine, after extraction of the commercially recoverable part of the ore (in this case, the lithiniferous mica). With the EMILI project, Imerys is seeking to reduce the volume of waste rock at source by:

• Recovering some of the ore and elements contained in the Beauvoir granite, in particular, feldspar and tin;
• The use of waste rock and tailings to gradually backfill the mine's extraction chambers. 

However, due to the increase in volume of mine rock, it is not possible to put everything that has been extracted back underground (a rock takes up more volume once it is extracted - and crushed - than in its original form).

Imerys therefore plans to use the remaining waste rock and tailings (510,000 metric tons per year) to backfill the Beauvoir Kaolin Quarry.

Recovering conversion co-products and tailings

Conversion transforms lithium into lithium hydroxide. To achieve this, it must be dissociated from the other constituents of the mica (iron, aluminum, silicates, etc.) using reagents. These different elements react with each other to form new products.

Some of them could be recycled. Calcium carbonate (limestone), for example, is one of the minerals used in the industry and could potentially find new outlets. Another example is sodium chloride, which is generally used to remove snow and ice from roads. However, some elements are not yet commercially viable.

Leaching and neutralization tailings make up the bulk of these and could be used to backfill old quarries. However, discussions between manufacturers are continuing in order to find as many solutions as possible for the majority of the tailings.