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Increasing Mill Shell Life In Grinding Mills Using Mill Liners

Grinding mills are generally used for crushing ores.The typical structure of a grinding involves a bulky rotatable drum which contains the grinding media.Usually steel balls or rods are used as the grinding media.Mill lining systems form an essential part of a grinding mill.They protect the mill shell from the abrasive environment inside and help in increasing its longevity.Mill liners are placed on the interior surface of the grinding shell.They provide the strength and resistance which is required when it is in operation.Generally, all the surfaces that come in contact with the pulp are lined, in order to take the wear, and consequently conserve the strength and rigidity of the barrel assembly.Liners in grinding mills grinding mills liners have alternating bars of alloy steel and strips of an elastomer, mostly rubber.It is joined together on a backing plate which is adequately flexible that the liner may be flat when manufactured, but can be fitted against rounded portions of the cylindrical sidewall of the mill by attaching bolts.Liners for its shells are made in slabs or blocks so that they can be attached to the interior of the mill through a discharge-end opening or a manhole.Typically, the maximum an individual block can weigh is from 55 to 80 kg as heavier blocks are difficult to handle physically.Selection of liners there are various factors on which the choice of liners depends upon.These factors include tumbling medium, sizes of feed and product, charge action desired, grinding efficiency, hardness of the ore, and cost of production.For example, ribbed liners are used for coarse products whereas non-ribbed liners are used for finer products and smooth liners for ultrafine products.As a standard the design of lining systems should be such that it is wear-resistant and abrasion resistant, withstand impact of the grinding media and promote the most favorable motion to the charge.Functions of mill liners irrespective of the size or type of the mill in which the liners are used, mill lining systems serve numerous functions that are important for maintenance as well as the actual grinding process.Guarding the mill shell from the aggressive impacting of the feed is the primary purpose of ball liners.The second key function of a liner is to transmit the rotary motion of the mill to the charge and grinding media.Apart from these basic functions, liners provide corrosion and abrasion resistance to the shell surface.They also facilitate sanitation and cleaning and increase the flow of the pulp.Lining mill surfaces prevents wear and associated damage to the structural members such as the mill shell, heads and trunnions.Finally it acts as the final link in the conduction of energy to the tumbling load or the charge.

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