Home Education Fillers for Polymer Applications
A major use of magnetite is to make high-density concrete used in hospitals for radiation shielding of the radiology unit among others. Adding magnetite gives good-quality concrete and allows walls that are thinner by 40% without sacrifice in radiation-blocking performance (Creutz and Downes 1949). One recent example is the Puijo Hospital in Finland.
Similarly, magnetite can be used to shield against microwaves as mentioned above or to make plastics x-ray opaque (Hein et al. 2013). Radio-opaque fillers are used in dental and medical implants to make the plastics visible. Magnetite has also been found effective for gamma ray shielding.
Sources of Magnetite
Magnetite occurs naturally and may also be produced synthetically (Schwertmann and Cornell 2000). Synthetic magnetite is usually favored when nanoparticles are required for scientific studies or for special applications such as immunodiagnostics or protein isolation. As mentioned, the smaller, synthetic type tends to be somewhat unstable where its high surface area makes it more prone to oxidation.
Natural magnetite occurs the world over. It can be separated from beach sand using a magnet and is also found in substantial deposits that can be mined. LKAB Minerals have spearheaded the drive to develop magnetite as a specialty filler for plastics. It has been shown that their natural magnetite from northern Sweden has exceptionally high purity (Muller et al. 2003) and even qualifies for food contact applications in plastic.
|< Prev||CONTENTS||Next >|