Wet magnetic separation

Fig. 16. Operating components of various separators (a) Jones continuous high, intensity wet magnetic separator (10), (b) canister-type high intensity...

In the case of a high-intensity wet magnetic separation process, the principal force acting to resist particles from being captured in the matrix is the fluid drag force, FD, which is given by the expression ... 

Low intensity magnetic separators are used to upgrade iron ores containing magnetite. Dry separators are used for coarse (up to 100 mm in size) ore and wet separators are used for fine (—9.5 mm) ores. 

High intensity magnetic separators are used to upgrade iron ores containing hematite or ilmenite. Dry separators require ore that is finely sized and bone dry. They are dusty, expensive, and have a low capacity. Wet separators have larger capacity, are less dusty and can handle ore sizes up to 1 mm. 

Fig. 15. Wet drum low intensity magnetic separator tank designs (a) concurrent, (b) counter-rotation, and (c) countercurrent (6) (d) shows the operating...

A single wet dmm separator is typically used in plants where the feed soHds are in the 10—15% range. Extremely dilute feeds make magnetic recovery more difficult and feed volume should be reduced by a factor of 0.5—0.75 for such dilute feed. Por soHds in the 20—25% range, either single-dmm 914-mm units or double-dmm 762-mm units are recommended. Above 25% soHds, 914 mm dia double dmms are recommended. 

Typically, ore bodies are relatively low in iron content. Iron minerals are finely divided in a gangue matrix. Wet grinding is usually required to Hberate the iron minerals, although some beach sands may have Hberated iron mineral values. Wet dmm separators are limited to the treatment of material <10 mm. The magnetic dmm separators appHed are usually related to the grinding circuit required to Hberate the iron mineral, and are typically designated by appHcation as cobbers, roughers, or finishers. 

Desired Magnetic Kecore. In ore concentration, maximum recovery is desHed at all times. Rejection of middling particles, although sometimes desHed, is difficult to accomplish on wet magnetic dmm separators. 

Fig. 10. Wet high, intensity magnetic separator using cryogenically cooled coils and a stationary matrix where A is the feed control for top-fed or retention time control for underfed operation and B is the feed control for underfed or retention time control for top-fed operation.

FIG. 19-45 Wet-d rum-magnetic-separator arrangements, [a) Counterrota-tion-type wet magnetic drum separator. (Couttesif of Sola International, Inc.) (h) Concurrent-type wet magnetic double-drum separator, (c) Countercurrent-type wet magnetic double-drum separator. 

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