The handling of bulk products in industries such as mining or package shipping involve transporting or moving products along a conveyor unit. For example, in the coal mining industry, a conveyor unit is a linking piece in the coal-handling chain. The components of a conveyor unit include conveyor belts and conveyor chutes. A typical part of the coal-handling process involves using an input chute to deliver mined coal to a conveyor belt, then transporting the coal to a discharge chute. Both the input chute and discharge chute include a sloping metallic trough or slideway having an angle of repose adjustable to suit the desired speed at which the coal, via gravitational inducement, will traverse the input chute to be loaded onto the conveyor belt and traverse the discharge chute in the course of being directed to storage or shipping processes.
The chute itself is sometimes made of manganese steel for heavy impacts, or high chrome steel or chrome molybdenum where only sliding abrasion is the problem. However, an unlined metallic chute may nonetheless incur wear damage fairly quickly due to impact, abrasion, and twisting forces imposed by coal and other bulk materials. In some operations, this problem is addressed by adding a protective lining to the chute.
As is well-known in the art, ceramic brick chute liners are frequently used to provide resistance against wear and abrasion. To achieve this objective, ceramic brick lining may be comprised of aluminum nitride, zirconia, alumina, or other inorganic, non-metallic solid material. It is also common practice for the ceramic layer to overlie a cushioning substrate of resilient rubber to protect against wear caused by impact energies. Rubber lining can be vulcanized onto chute surfaces, or adhered in sheets to chute surfaces. The thickness of the lining, as well as “shore hardness”, may be varied depending on the size of the product particles and the drop distance from conveyor to chute.
However, the flexibility of the rubber layer may not provide sufficient resistance to chute twisting, which is a significant contributing factor to the wear of the lining itself. Also, the insulation characteristics of the rubber layer may prompt the occasional need for radiant heaters in cold weather, to help protect against hardening of the rubber layer and consequent reduction of its shock-absorbing characteristics.
In addition, abrasion-resistant ceramic liners have proven difficult to secure to a cushioning substrate so as to form a protective lining that is sufficiently capable of enduring repeated surface impacts and abrasions. This results in dislodging of the ceramic tiles from the cushioning rubber substrate and increases the frequency with which the ceramic tiles need replacing. Therefore, there is a need to enhance the insulation characteristics of linings to mitigate against the hardening of the rubber layer in cold weather, while reducing the maintenance needs and resulting production costs associated with frequent ceramic tile replacement.