MINING AND PROCESSING
The starting point for our refractory minerals is securing the highest quality reserves for our product portfolio. All over the world, we have secured these resources to ensure our long-term objective of secure supplies given the long-term nature of our business.
Expertise in Mining & Geology
The very nature of these reserves requires high-level geological expertise to identify, secure and develop them in a safe and sustainable manner. Ensuring the longevity of our assets further strengthens our ability to meet our industy’s long-term requirements.
As a result of the beneficiation know-how we have developed over the years, we are able to produce pure andalusite concentrates from every deposit. The characteristics of each ore body are taken into consideration to define the most suitable beneficiation process. A combination of magnetic, heavy media and electrostatic separation and, in some cases, a flotation process is used to obtain the best andalusite concentrate.
Sintering is a very important transformation step in our calcined products. It is during a high temperature process that a ceramic transformation takes place.
Depending on the final product, and its targeted characteristics, we will calcinate at different temperatures and using various sintering cycles. Molochite is produced in a long tunnel kiln where the material is extruded into bricks and loaded on kiln cars. At a temperature above 1500°C for 3 days from cold to cold, the product is totally transformed into mullite and glass.
The rotary kilns used for sintered mullites and chamottes are the most common kilns for sintering the silico-aluminous material. Imerys Refractory Minerals operates 13 rotary kilns in the US, in France and in Ukraine. With a good ratio output versus energy consumed, we continuously improve the automation of burners and controls in order to guarantee the best transformation. From clays to calcined products is a key stage in the mineralogical transformation. The product is stabilized after sintering and will be able to support high temperature in harsh conditions.
Imerys Refractory Minerals’ milling technology is a complex process where the methods depend both on ore type and on the final application. To obtain exactly the right particle size and top cut for a given application, we use a variety of techniques including compressed air, steam and impact milling – many of which have been developed in-house. Median particle sizes can range from less than 1 micron to 15 microns, and top cuts from 6 microns to over 100 microns.