Gyratory and Cone Crushers

Once the magnesite rock has been blasted, it is generally loaded onto trucks and transported to the primary crushing operation. Primary crushers are heavy-duty machines and handle dry run of mine feed material as large as 1 m. There are two principle types of primary crushers in operation— gyratory crushers and jaw crushers, with the gyratory type being the most common. 

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Primary crushers used are jaw, gyratory, impact, and toothed roll crushers. Impact mills are limited to limestone and softer stone. With rocks containing more than 5 percent quartz, maintenance of hammers may become prohibitive. Gyratory and cone crushers dominate the field for secondary crushing of hard and tough stone. Rod mills have been employed to manufacture stone sand when natural sands are not available. 

Compression is the most usual comminution force for brittle materials. Materials are compressed between two heavy-duty metal surfaces. Crushers based on compaction force are jaw, cone, gyratory, and roll crushers. These are most widely used to reduce the size of coarse rocks and minerals particles. In soUd waste treatment, their use is not widespread, because compression force, in most cases, simply deforms the materials but does not change their size (e.g., metals, paper, plastic, organics). 

Hard and tough Mica Scrap and powdered metals Jaw crushers Gyratory crushers Cone crushers Autogeneous mills Ball, pebble, rod and cone mills Tube mills Vibration mills Ball, pebble and cone mills Tube mills Vibration and vibro-energy mills Fluid-energy mills Moh s hardness 5-10, but includes other tough materials of lower hardness... 

Crushers and grinders Cone crusher Gyratory crusher Jaw crusher Hammer mill... 

Beneficiation. Iron ore coming from the mine must be properly sized. A gyratory crusher is normally used for primary crushing down to approximately 300 mm (see Size reduction). Secondary crushing down to 25 mm can be done in a cone crusher. Fine grinding can be done by rod mills followed by either ball or pebble mills. In some cases, autogenous grinding can be used to replace the cone cmsher and rod mills. 

Primaiy crushers have a steep cone angle and a small reduction ratio. Secondaity crushers have a wider cone angle this allows the finer product to be spread over a larger passage area and also spreads the wear over a wider area. Wear occurs to the greatest extent in the lower, fine-crushing zone. These features are further extended in cone crushers therefore secondary gyratories are much less popular than crushers, but they can be used as primaries when... 

PRIMARY AND SECONDARY CRUSHERS Gyratory Cone Crushers... 

Jaw crusher feed diameter 0.1 to 1.5 m reduction ratio 5 1 to 10 1 capacity 1 to 300 kg/s Mohs hardness <9 (reduction by compression). Gyratory crusher feed diameter 0.75 to 1.5 m reduction ratio 5 1 to 10 1, usually 8 1 capacity 140 to 1,000 kg/s Mohs hardness <9. More suitable for slabby feeds than jaw crusher (reduction by compression). Roll crusher feed diameter 1 cm reduction ratio 5 1 to 10 1 capacity 0.3 to 20 kg/s Mohs hardness <7.5. Suitable for softer, friable, and nonabrasive materials. OK for wet and sticky materials. Cone crusher and short head cone feed diameter <25 cm reduction ratio 5 1 to 10 1, usually 7 1 capacity 5 to 300 kg/s Mohs hardness <8. Usually secondary or tertiary crusher. Impact crusher pulverizers, shredders, or smooth roll feed diameter 1 cm with a reduction ratio of 7 1 to 10 1 capacity 0.3 to 50 kg/s. Mills, hammer, feed diameter 10 mm, reduction ratio 10 1 to 50 1, capacity 0.01 to 5 kg/s Mohs hardness <4.5. Maximum fines feed not hard or abrasive. Mills, ball, and rod feed diameter 0.5 mm with a reduction ratio of 10 1 to 50 1 Mohs hardness <9. Mills, autogenous, semiautogenous feed diameter 200 mm, reduction ratio 10 1 to 50 1 capacity 0.1 to 100 kg/s Mohs hardness <6. Mills, fluid energy feed diameter 50 pm reduction ratio 10 1 to 50 1 capacity <2 kg/s Mohs hardness <4.5. 

Cone crushers are increasingly being used as secondary and tertiary crushers and are frequently operated in closed circuit (i.e. with over-sized particles being screened out and recycled to the crusher) to produce a well-defined top size, with minimum fines. They have similar reduction ratios to gyratory crushers (4 1 up to 6 1) and produce a more slabby product than impactors. 

Heuristic 49 Crushing of coarse solids. Use a jaw crusher to reduce lumps of hard, abrasive, and/or sticky materials of 4 inches to 3 feet in diameter to slabby particles of 1 to 4 inches in she. Use a gyratory crusher to reduce slabby materials of 8 inches to 6 feet in size to rounded particla of 1 to 10 inches in diameter. Use a cone crusher to reduce less hard and less sticky materials of 2 inches to 1 foot in diameter to particles of 0.2 inch (4 mesh) to 2 inches in diameter. 

Gyratory Crusher. A primary crusher for hard rocks such as the quartzite used in silica brick manufacture. The material to be crushed is fed into the space between a vertical steel cone and a similarly shaped steel casing the cone rotates eccentrically to the casing (cf. cone crusher). 

Cone crushers operate on the same principle as gyratory crushers. This allows a gradual reduction of the area between the two cones. The rotating cone or mantle is inclined, thus providing a combination of impact loads and compression loads. By comparison with the gyratory crusher, the outer bowl is inverted, and the mantle rotates at much higher speeds. There are two types of cone crushers ... 

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