Rubber types liners

Liner wear increases with the size, hardness, and sharpness of feed more than with ball size. The hardness of manganese steel corresponds to softer types of ore, while Nihard is about the same as magnetite [Moore et al.. International J. of Mineral Proce.s.sing, 22, 313-343 (1983)]. Quartz and pyrite are considerablv harder than any metals used. Rubber, being resihent, is less affected by ore hardness, and therefore has the advantage with harder ores. Low-charge volume below 35 percent results in increased wear since the liners are not protected bv a covering of ore. Several studies indicate that wear increases at least proportional to the square of mill speed in percent of critical. 

Two types of seals for the vials have been employed and both give satisfactory results. Aluminum, one-piece, crimp-on seals used with serum vials and Teflon faced septa are acceptable if the seal is properly made and maintained during shipment. However, several years of experience indicates a success rate significantly less than 100% in making proper seals of this type in the field. Therefore simple screw cap vials used with the Teflon faced septa were evaluated and found to give equivalent results and a very high rate of acceptable samples. Narrow mouth screw cap bottles with Teflon-faced silicone rubber septa cap liners are strongly recommended for sample collection. 

As with inclined discs, the character of the internal surface is important in producing the correct tumbling action in the drum. In iron ore balling, the steel drum is commonly lined with a layer of concrete (approx. 1 in. (2.5 cm) thick) or by expanded metal. Various types of internal scrapers, depicted in Fig. 3.18, are used to limit build-up of material on the inside surface and to provide a uniform layer to promote the correct rolling, tumbling action in the drum. Rubber flaps and liners as well as external knockers are used to limit build-up in fertilizer processing. 

Both all-rubber liners, and rubber liners with metal lifter bars are currendy used in large ball miUs [McTavish, Mining Engineering, 42, 1249-1251 (Nov. 1990)]. Both types (Fig. 20-32) have rubber-liner plates, separated and held in place by lifter bars. Rubber liners have the following advantages Abrasion and impact resistance, 15 percent... 

FIG. 20-32 Types of ball-mill liners (a) combination liner [McTavish, Mining Engineering, 42, 11, 1249—1251 (1990) Exton Industries, Inc.] (h) all-rubber liner [Moller and Brough, Mining Engineering, 41, 8, 849-853 (1989) Skega Ltd.]. 

BR is used in nearly all parts of the tire with the exception of the inner liner it is always blended with natural rubber (NR) or styrene-butadiene rubber (SBR). Apart from the extrudability, in NR blends the Nd-BR polymers exhibit advantages in all important compound and vulcanizate properties. Also, in SBR blends Nd-BR leads to the best vulcanizate properties in comparison with all other types of BR. 

Protective liners such as concrete, neoprene-type rubber, or plastics also may be used to prevent hydrogen attack. Other procedures which are helpful are removal of cyanides, removal of sulfur compounds from feedstocks, and the injection of polysuffides which form a film over the interior of the vessel. ... 

The tire is a complicated composite product consisting of tread, undertread, carcass, inner liner, bead, and sidewaU. Many different types of rubber... 

Abrasion is usually a major consideration in pump selection. Except for the mild chemical-type duties already referred to, slurry pumps are of special construction, essentially to resist abrasion to the pump and its shaft seals but often also to permit fast maintenance and liner or component replacement for very abrasive duties. Generally either replaceable rubber lining or specially hard abrasion-resistant alloys are used shaft seals are of special design, and are usually continually flushed with clean water. Impeller tip velocities are kept within proven limits for the application. Power transmission is often through V-belts rather than direct-drive couplings, to permit exactly the required speed to be obtained (rather than synchronous speeds) and to permit speed optimization in service (varying the impeller diameter is not so convenient). 

Covered casings are more expensive because their construction is more elaborate. Following an inner liner that may be either metaUic or plastic, the casing is reinforced with layers of steel braid and finished off with a final outer sheath of rubber or plastic. This type of casing permits the flexible shaft to operate under water, hydraulic fluid, or other liquid, so long as the fluid does not attack the elastomeric outer covering. 

The gas and liquid are often placed in contact in a large vertical cylindrical tower. Several tower designs are shown in Fig. 28.3. Packed towers, spray towers, tray towers, and reverse jet-type scrubbers have aU been used to treat acid plant tail gas. They are usually constructed of fiber reinforced plastic with a suitable corrosion-resistant liner. Unlined stainless steel and rubber-lined carbon steel are also used. 

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