FUNDAMENTALS

basic mining process/terminology

 

associated functions

   

Coal transport
 

Coal transport

Once cut, the coal has to be transported from the face area to the surface. There are localized transport systems at the mining face areas to carry the coal from the cutting machines to the main transport systems. These localized transport systems (shuttle cars, AFC's, BSL's, etc) are dealt with in following sections relative to the different types of mining. This section refers to the main transport systems out of the mine.

Before the development of suitable conveyor belts, coal was transported from the mine by rail transport systems, but today coal transport is almost invariably by conveyor belts. In a mine with drift or adit access, the conveyor transport can be all the way to surface but in a mine with only shaft access winding or hoisting of coal in the shaft is required.

The use of conveyors introduces a requirement for roadways to be mined as straight as possible with changes of direction minimized as far as possible. Every change of direction will require a new conveyor drive installation which involves the drive pulleys and motors, a tensioning device, electrical control equipment and transformers, transfer chutes and cleaning arrangements. This is a lot of equipment which requires space for installation (usually necessitating additional excavation), and requires continual maintenance and cleaning. Transfer points are always potential sources of problems as chutes can be easily blocked, dust is created and spillage is common. A few large installations are better than a lot of small ones. This has an influence on mine planning.

Conveyor belts in drifts are usually special types because of the large change in elevation involved. The belt itself usually requires extra strength and steel cord belts are commonly used.

It is often beneficial to have a provision for storage in a conveyor system to both allow operations to continue for a period in the event of a delay in the downstream section and to optimize the coal conveying system capacity. This usually takes the form of a vertical excavation either above or below the seam, referred to as a "bin" the conveyors passing through a short drift from the seam to the top or bottom of the bin.

A method of coal transport used in some special instances, where mining is taking place in steep seams, is hydraulic transport. There are some mines (notably in New Zealand) where the coal is mined hydraulically using high pressure water jets (or "monitors"). From that point gravity is used to carry the water and coal along steel troughs or "flumes" to holding dams where it is either flumed or pumped from the mine. The coal and water are subsequently separated, the water recirculated to the mine and the coal prepared for market.

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