Magnetic separator drum magnets

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

Drum and Pulley Magnets Since Thomas Edison invented and developed the magnetic pulley for the concentration of nickel ore, drums and pulleys have become the most common types of magnetic separators. These devices can be built with either a permanent magnet or an electromagnet, and the drum separator can operate with... 

Alternating-polarity drum separator. This device is used for the treatment of coarse material (minus 40 mm, plus 0.15 mm) containing strongly magnetic particles when a high-grade concentrate is required. The capacity of this device varies with feed-particle size, up to 100 t/(h m). 

High-speed, low-intensity drum magnetic separator. This device is designed to handle very fine material (minus 0.15 mm and finer) to produce a high-grade magnetic concentrate. 

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. 

TABLE 19-21 Influence of Magnetic-Drum Diameter on Separation ... 

FIG. 19-46 Magnetic-field distribution charts, a) Concurrent and counter-current wet drum magnetic separator, 1.2-m diameter, (h) Counterrotation wet drum magnetic separator, 1.2-m diameter. (Coutiesy of Sala International, Inc.)... 

In a dry drum-type magnetic separator, the magnetic force, Fm, acting on a particle on the drum surface is given by... 

Since Fm and Fc are both proportional to the particle volume, the particle size does not figure in the above relationship for the critical rotation speed. This means that the dry drum type magnetic separator can be used in the treatment of a feed containing particles with a wide range of sizes. 

Low intensity wet drum magnetic separators, 15 442-449 Low internal phase ratio emulsions,... 

Rotor bodies, in steam turbines, 23 231 Rotor electrostatic separators, 16 643-644 Rotor rotating converter, 16 151 Rotors, molecular, 17 59-61 Rotor spinning cotton yarn, 3 17 Rotor-stator devices, 10 127 Rotor-stator disperser, 3 701 Rotor-stator mills, 13 65 Rotor-stator mixers, 16 674-675 Rotosil process, 22 412 Roughages, as ruminant feeds, 10 863 Roughing, in mineral separation, 16 604 Roughing services, magnetic drums used in, 15 446... 

Wet deposition, 26 10 Wet dispersion image analysis, 18 147 Wet drum concentrator selection, feed factors in, 15 446—447 Wet drum magnetic separators, low intensity, 15 442—449 Wet drum ore concentrator specifications, 15 447-449... 

Feed Solids Content. A good HMS plant operation keeps the medium as free of fines as possible by effective screening of the heavy-media separation vessel feed. Reduced fines reduce viscosity problems in the medium and result in sharper separation of sink and float products. It also improves magnetic recovery on the magnetic drum separators and gives a cleaner magnetic concentrate. The use of cyclones in the HMS circuit, either as the heavy-media separation vessel or as a densifier for rinse or wash water, increases the solids content and must be evaluated in selecting the media recovery wet dmm separators for plants in which cyclones are used. 

A single wet dmm separator is typically used in plants where the feed solids 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. For solids in the 20—25% range, either single-drum 914-mm units or double-dmm 762-mm units are recommended. Above 25% solids, 914 mm dia double drums are recommended. 

Recommended Feed Volumes. Both feed volume and magnetic solids discharge rate should be balanced in selecting media recovery drum size. The feed rates typically recommended for single and double wet drum separators depend on drum diameter. For a 762 mm dia single drum, the recommended feed rate is 50—55 m3/(hrn) for either a 914 mm dia single drum or a 762 mm dia double drum, 55—70 m3/(h-m) for a 914 mm dia double drum, 70—95 m3/(h-m). 

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

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