MAGNETITE 101

Magnetite is a very heavy, magnetic, iron oxide mineral.

Its chemical formula is Fe₃O₄.

The Moh’s Scale hardness is 5.5 to 6.

Pure magnetite has a specific gravity of 5.1, meaning that it is 5.1 times heavier than the same volume of water. In practical terms a cubic metre of water weighs 1 tonne (1000 kg or 2200 lbs) while a cubic metre of magnetite weighs 5.1 tonnes (5100 kg or 11,220 lbs).

The mined ore from the Micrex Projects runs on average 4.65 to 4.8 for specific gravity.

The combination of hardness, weight and for certain applications, magnetic properties, makes magnetite a desirable industrial mineral beyond its iron content.

Magnetite worldwide is a valuable resource as an iron ore. With the upswing in the iron and steel industry magnetite resources are being consumed at a prodigious rate.

This leaves little supply available for other magnetite users.

North American industrial magnetite users have been forced to source magnetite from offshore or do without. What few sources of industrial magnetite remain on the North American continent are dwindling quickly and users have reported that with so many markets fighting over the same resource that quality has dropped, costs have escalated and supply has become almost impossible to secure.

In some cases the lack of a secure and good quality magnetite supply has forced companies to abandon the effort to produce various products.

Off shore suppliers of magnetite have a reputation for poor quality control, uncertain supply and widely variable costs – particularly shipping.

The Micrex Magnetite Projects will offer a secure, high quality source of supply to the wide range of industrial users desperate for magnetite.

Heavy Concrete

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 radioactivity in x-ray facilities. Beyond that however heavy concrete has been discovered by other industrial users for use as counterweights 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 plan 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.

Municipal water plants have not been using magnetite because of lack of knowledge and lack of supply.

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. This allows heavier waste materials, such as pulverized rock, to sink and separate from the lighter coal. Magnetite can be recovered using magnets and re-used again in the coal upgrading process without the use of industrial chemicals. This is not only a benefit to the operator, but is an environmentally conscious method of utilizing this valuable resource. About 90% of the magnetite can be recovered for reuse from the process, and the remaining 10% must be must be replaced. This results in a steady demand for new magnetite.

Not only coal producers use this system. Potash producers and diamond mining also use heavy media separation systems.

Decorative Landscaping Accents

An end user has identified the dark glossy ore as a desirable specialty accent rock for landscaping.

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 enhance the weight.

Chemicals

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.

This page was updated on September 9, 2008.