Imerys Group is particularly sensitive to issues regarding energy consumption, as much in response to the problem of climate change and because energy cost constitutes a significant portion of total production cost.
Every year around 1,000,000 MTs of bentonite are mined on Milos island by Imerys Industrial Minerals Greece S.A. and almost all of that quantity has to be dried to about 15% on average. Milos is the largest European mining center for bentonite, a mineral with applications in foundries, iron ore pelletizing, civil engineering, per litter markets to name a few. It is estimated that Imerys production on Milos covers some 30% of the total European bentonite production.
Significant energy saving is achieved by exploiting Milos’ climatic conditions -that is high temperature and wind during summer- for the natural pre-drying of bentonite in open fields, resulting in approximately 35% annual energy savings, compared to the energy that would be required if industrial drying was exclusively used.
It is estimated that some 100.000 MTs of water are evaporated on a yearly basis through this field drying process. This is equivalent to actual savings of about 7,500 MTs of annual heavy fuel oil consumption, corresponding to CO2 emissions reduction in the range of 24,000 MT per annum. Milos is an island in the Aegean Sea, an energy importer (fuel transportation with vessels) and the above savings constitute a significant reduction not only of Imerys’ energy consumption but of the total energy consumption of the island.
Another indirect effect of air drying is the increase in resource efficiency through the effective blending of variable bentonite qualities, allowing no sacrifice of raw materials and without undermining the quality for the end application. This is based on the fact that air drying takes place in large fields with sequential deposition of bentonite layers of relatively small thickness on top of each other. Each layer is left to dry for a couple of weeks, being intermittently exposed to air with use of agricultural type plough equipment. This process gives a lot of flexibility in blending, allowing optimal use of reserves of variable quality. In addition the mild drying conditions do not lead to destruction of the crystalline structure of bentonite, which is inherently associated with industrial drying, increasing therefore resource efficiency further.