Uses for Magnetite

Heavy Concrete

When used as the aggregate portion of a concrete mix, magnetite increases the density of the concrete to twice that of standard concrete. This so called "heavy concrete" has become a common building material in nuclear plants as well as (in brick form) for the mitigation of radiation in x-ray facilities. Beyond that, however, heavy concrete is used to make counter weights and as thermal mass in heat storage situations. The most common and growing use is in the design and building of passive solar collection in domestic housing. Still in its infancy, this application has grown out of the search for more efficient heat retention beyond that offered by standard concrete.

The denser the material, the greater its thermal retention properties, and heavy concrete offers twice the mass in the same volume as standard concrete. Being just as strong and flexible as standard concrete, it can be used in the very same applications and offer substantially improved thermal characteristics.

The use of heavy concrete in nuclear power plants is dependent on new plant contracts and old plant repairs. It does not represent a stable consumption but can be an important add-in market in the short term.

The most stable use at the moment is in the production of counter weights. Micrex has had market interest from producers making counter weights for everything from washing machines to pipeline anchors to crane counterweights.

One other emerging market for heavy concrete is for shotcrete application in uranium mining to reduce radiation exposure to miners. A company in Alberta has the patent on a specialty process using heavy concrete shotcrete and has tested Micrex's magnetite, finding it ideal for their use.

Water Filtration

Sand and gravel bed filters used by many municipal water treatment plants can realize benefits by using heavier aggregates in the sand bed.

The heavier specific gravity of magnetite aggregates allow a more aggressive backwash in the cleaning phase without loss of product, and because magnetite is magnetic it can be easily scavenged back from waste water streams for reuse.

Heavy Media

Magnetite is an essential part of the "heavy media" process in coal mining. In the form of a very fine powder, it is added to water to form a heavy media slurry that has a higher specific gravity than water alone. When coal from the mine is pulverized and added to the slurry, the heavier waste materials, such as rock particles, will sink and separate from the lighter coal. The heavy impurities are then siphoned from the bottom of the slurry and the light coal is skimmed off the top. Using magnets, magnetite can be easily recovered from the waste and coal streams and then re-used in the coal separation circuit. Recyling the magnetite provides a cost saving to the operator, and is an environmentally conscious method of utilizing this valuable resource. About 90% of the magnetite can be recovered for reuse from the process, but the remaining 10% must be must be replaced. This results in a steady demand for new magnetite.

In addition to coal producers, potash producers and diamond mines also use heavy media separation systems.

Mineral Fillers

This is a relatively new market for Micrex and is based on certain plastic producers' search for a denser end product. Some plastic products (pipeline cleaning "pigs" for instance) can benefit from added weight. Magnetite can be added as a very fine powder to the plastic mix to increase the weight.


Magnetite is an excellent source of iron for the production of iron-based chemicals like ferric chloride and ferric sulphate, that are used as alternatives to aluminum hydroxide. Aluminum hydroxide is used to help clarify raw water in municipal water purification plants, but concerns about aluminum in drinking water have prompted consideration of alternative chemicals.

Other chemical uses include high iron fertilizers, pigments and sediment control products.

Landscaping Accents

The dark, glossy magnetite ore is a desirable specialty accent rock for landscaping.