Magnetic Separation: Industrial and Lab Scale Applications
Magnetic Separation: Industrial and Lab Scale Applications Magnetic Separation: Industrial and Lab Scale Applications
Figure 3. Kaolin decolorizes to white after magnetic separation . Courtesy of R.Weller/Cochise College and U.S. Geological Survey. b. Steel production Conventional methods for cleaning steel mill waste and process waters include sedimentation, flocculation followed by sedimentation, and fixed bed filtration. Sedimentation methods require large areas for settling tanks and clarifiers (Oberteuffer 1975). Table 2 lists some of the contaminants generated in a steel production process. On average 1 ton of steel needs 151 tons of water for cooling, cleaning purposes. Apparently, the process generates many magnetic particulates. Those particles, especially the ones in the gas and hot water streams, need vast space and heavy machinery for removal by regular methods, filtration, flocculation, etc. Magnetic separation, instead, offers great time, space and cost savings (Oberteuffer 1975, Harland 1976, Gerber 1983 p133). In a sample treatment at Kawasaki Steel Corporation of Japan, a 3 kOe field strength, 2.1 m
diameter magnetic filter removes 80% of contaminants from the cooling wastewater of vacuum degassing process (Hirschbein 1982). Sources Contaminants Coke production Non-magnetic particles, dissolved organics, oil Iron making Magnetic particles, dissolved organics Steel making Magnetic particles Hot forming Magnetic particles, oil, acids Cold finishing Magnetic particles, oil Table 2. Sources of contaminants in a steel production process (Oberteuffer 1975). Power plants (both conventional and nuclear) with wastewater, steam and cooling systems often requires filtering off the ferromagnetic or paramagnetic particulates clumping on the thermal, process streams (Berger 1983 book page). Fly ash from coal power plants has 18% iron oxides. Magnetic filtration is capable of saving 15% of fly ash and recycling it. Estimates show that this can replace some of the magnetite used in industry (Hirschbein 1982). Figure 4 shows an example of a ball mill separator used in these operations.
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diameter magnetic filter removes 80% of contaminants from the cooling wastewater of<br />
vacuum degassing process (Hirschbein 1982).<br />
Sources Contaminants<br />
Coke production Non-magnetic particles, dissolved organics, oil<br />
Iron making <strong>Magnetic</strong> particles, dissolved organics<br />
Steel making <strong>Magnetic</strong> particles<br />
Hot forming <strong>Magnetic</strong> particles, oil, acids<br />
Cold finishing <strong>Magnetic</strong> particles, oil<br />
Table 2. Sources of contaminants in a steel production process (Oberteuffer 1975).<br />
Power plants (both conventional <strong>and</strong> nuclear) with wastewater, steam <strong>and</strong> cooling<br />
systems often requires filtering off the ferromagnetic or paramagnetic particulates<br />
clumping on the thermal, process streams (Berger 1983 book page).<br />
Fly ash from coal power plants has 18% iron oxides. <strong>Magnetic</strong> filtration is capable of<br />
saving 15% of fly ash <strong>and</strong> recycling it. Estimates show that this can replace some of the<br />
magnetite used in industry (Hirschbein 1982). Figure 4 shows an example of a ball mill<br />
separator used in these operations.
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