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Magnetic Separation: Industrial and Lab Scale Applications

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Figure 3. Kaolin decolorizes to white after magnetic separation . Courtesy of<br />

R.Weller/Cochise College <strong>and</strong> U.S. Geological Survey.<br />

b. Steel production<br />

Conventional methods for cleaning steel mill waste <strong>and</strong> process waters include<br />

sedimentation, flocculation followed by sedimentation, <strong>and</strong> fixed bed filtration.<br />

Sedimentation methods require large areas for settling tanks <strong>and</strong> clarifiers (Oberteuffer<br />

1975). Table 2 lists some of the contaminants generated in a steel production process. On<br />

average 1 ton of steel needs 151 tons of water for cooling, cleaning purposes. Apparently,<br />

the process generates many magnetic particulates. Those particles, especially the ones in<br />

the gas <strong>and</strong> hot water streams, need vast space <strong>and</strong> heavy machinery for removal by<br />

regular methods, filtration, flocculation, etc. <strong>Magnetic</strong> separation, instead, offers great<br />

time, space <strong>and</strong> cost savings (Oberteuffer 1975, Harl<strong>and</strong> 1976, Gerber 1983 p133). In a<br />

sample treatment at Kawasaki Steel Corporation of Japan, a 3 kOe field strength, 2.1 m

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