The life of the Rubber liners can be predicted to a great extent by comparing the DIN Abrasion loss values and tear strength of the liner to the one whose life is known.

A very good quality Chute liner will have an abrasion loss value of less than 85 cu. mm and tear strength (die C) above 80Kg/cm.

The wear out of the Chute Liners ocurs due to sliding wear and also due to cutting and chipping by the sharp materials hitting the Liners at high velocity at acute angles.

Rajagopal ■

A simple measure of rubber liner life prediction is possible but with many caveats.

Rubber liner life, based on material flow prediction, is a complex problem. The best source of simply predicting rubber life is to find an equivalent flow analogy. To do this you also need to quantify the variables that are at work between the comparisons. This is not so easy. Rubber, rock properties, and flow dynamics dependent on feed chute geometry. A simple test result analogy and the intended predicition can be seriously biased by the flow geometry.

Discrete Element Modeling (DEM) can provide a reasonably accurate measure of flow dynamics, depending if the many attributes are accurately portrayed as noted in the following comments. There are also differences between DEM codes and their ability to properly quantify these many attributes.

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There are two major catagories of damage to rubber already noted: a) abrasion or sliding wear and b) gouging or cutting damage. DIN or ASME testing for abrasion can give a clue to rubber performance, but only a clue when the analogy is close.

Gouging is more difficult. To predict if gouging will influence the damage index, you need to identify if there is sufficient rock kinetic energy to cause the liner or belt rubber surface fracture that will exceed the "surface energy" rating of the rubber. Tear resistance (tensile strength) is a partial measure of the "surface energy" constant. However, tear resistance does not tell you the rubber's strain rate properties that give details about impact damage. This is more difficult to determine, but doable. Again, analogies are a big help.

We do the analogies by calibrating damage on given installations where abrasion and gouging can be differentiated. A case example was the publication of the Palabora copper mine incline belt wear life change with chute geometry ('Technological Innovation Extend Life of Palabora’s Main Slope Belt; Nordell & Van Heerden, Beltcon 8). The primary crushed rock belt feeder chute modification demostrated the separation of abrasion and gouging damage. The problem was analyzed using DEM. Gouging damage shortened the belts measured rubber life to ~ 2.5 years. Abrasion would have yielded about 8 years of life as noted by the first 6 month's wear curve. Alteration of the chute geometry completely stopped gouging damage and increased the abrasion life to ~ 30 years. The damage was tracked to the end of mine life at about 8 years. After 8 years, less than 4 of the 18 mm belt cover was worn away.

Internet reference on this paper:

http://site.doublearrowbelt.com/Clie...ope%20belt.pdf

Abrasion damage is a product of many properties:

1. Rock size, shape, sharpness and density all contribute - large rock, slabby shape which resist rotation, sharp edges, and high rock density all apply greater stress levels to the rubber.

2. Higher velocity at impact and angle of impact play major roles on the degree of abrasive. An impact angle of less than 26 degrees substantially lowers impact damage in liners and onto belts.

In summary, to predict rubber life, you need the tools to measure each of the above influences and how they affect the rubber's damage indices. ■

Hi,

Information relating to the sliding wear resistance of various materials used in coke chutes, including rubber and polyurethanes:

http://www.omegaslate.com/producti.htm#cpvwrlm

Regards,

Mike. ■