Ilmenite is found all over the world. It is a common granular mineral that is mined and processed specifically for filter media that is used in wastewater treatment. Ilmenite is an oxide of iron and titanium. It is heavier than sand and is used as the bottom layer in trimedia filter systems. High-density materials are normally used in the filtration process because of their relative densities, either as “hold down” gravel, or as high-density media. All things being equal, the higher the density, the more desirable the material. However, sometimes other considerations such as availability, transportation cost, or even chemical properties may influence the optimal choice. Sand, anthracite coal, garnet and ilmenite are all used as filter media when adsorption and filtration are combined in a single unit water and chemical filtration process. The George L. Throop Company can supply and deliver ilmenite in many different sizes that is AWWA B100 and NSF 61 certified.
Because of its hardness, high specific gravity and the pounds per cubic foot, Ilmenite, when installed correctly, stays in its own layer holding down the layers underneath during backwash.
The layers above the ilmenite are lighter in weight (per cubic foot) and therefore they lift during backwash and dislodge the “floc” cleaning of the filter media. The Ilmenite is not used to replace silica sand but rather one or two support layers of Ilmenite are used beneath the silica sand. Ilmenite is so durable and heavy that the layers above will be replenished or replaced well before the Ilmenite and filter rock layers are replaced. Therefore, time and money are saved by using Ilmenite in a filtering system.