MATERIALS HANDLING: LOADING AND HAULAGE

FOR SURFACE COAL MININGReporters:Sarah Mae AjonDailyn Nivero

Materials Handling A material most commonly handled by the

mining industry is rock that has been fragmented either by mechanical or explosive methods.

This rock can be: an ore containing an economic mineral salable mineral product itself in a fairly undiluted

form waste rock that must be excavated to expose the

economic mineral deposit.

Materials Handling

In the simplest scenario, a loading device is used to load fragmented ore into a unit conveyance, which carries the ore to a facility where it will be beneficiated.

Typical units vary for different operations.

Coal Removal on Surface Mines

Coal is usually loaded by front-end loaders, loading shovels, or wheel excavators into off-highway, bottom-dump trucks for transport to the stockpile.

In small operations, it can be loaded into on-highway trucks for direct shipment to customers.

The coal is loaded out of the mining area and is taken to surface stockpiles, either to be shipped out by rail or transported to a power plant directly on the property (mine mouth operation).

Equipments for Loading and Haulage

Dozers and Scrapers In land clearing, topsoil removal, and

preparation of the mining area for subsequent unit operations, bulldozers and scrapers have extensive applications.

Currently, scrapers for rock have bucket capacities of 33 cubic metres (1,165 cubic feet; about 47 tons of material), and scrapers for coal have capacities of 43 cubic metres (37 tons). Bulldozers have blade capacities up to 30 cubic metres.

Equipments for Loading and Haulage

Dozers and Scrapers

Equipments for Loading and Haulage

Shovels and Trucks When the haul distances are small (for

example, 500 to 1,000 metres) and the overburden material soft, a fleet of scrapers can load, haul, and dump the overburden.

Where distances are very small (for example, 30 to 40 metres), mobile front-end loaders, or wheel loaders, may be used to load, haul, and dump.

Three types of shovel are currently used in mines: the stripping shovel, the loading (or quarry-mine) shovel, and the hydraulic shovel.

Hydraulic and loading shovels are available with capacities up to and over 30 cubic metres.

The capacity of the loading shovel is carefully matched with the haul unit into which the load will be dumped.

In open-pit coal mines, the haul units for overburden material are usually large, off-highway, end-dumping trucks; their capacities range from 35 to 250 tons.

The stripping shovel has a large bucket, usually sits in the pit on the top of the coal seam, digs into the overburden material, and deposits it in the adjacent mined-out area.

Stripping Shovel

Loading Shovel

Hydraulic Shovel

Equipments for Loading and Haulage

Draglines the most commonly used overburden-removal

equipment in surface coal mining. A dragline sits on the top of the overburden,

digs the overburden material directly in front of it, and disperses the material over greater distances than a shovel.

Compared with shovels, draglines provide greater flexibility, work on higher benches, and move more material per hour. The largest dragline in operation has a bucket capacity of 170 cubic metres.

Dragline

Equipments for Loading and Haulage

Wheel excavators a continuous excavation machine capable of removing up to

12,000 cubic metres per hour. The most favourable soil and strata conditions for BWE operation are soft, unconsolidated overburden materials without large boulders.

BWEs are widely employed in lignite mining in Europe, Australia, and India. In these mines, the wheel excavators deposit the overburden and coal materials onto high-speed, high-capacity belt conveyors for transport to the mined-out areas of the pit and the coal stockpile, respectively.

In the United States, wheel excavators have been used in combination with shovels or draglines, with a wheel handling soft topsoil and clay layers and a shovel or dragline removing hard strata.

Bucket-wheel Excavator

Loading: Lay-Out of Mining Areas

1. Provide sufficient operating room whenever possible

2. Develop mine standards on typical operation lay-out for major equipment

3. Enforce adherence to the standard designs

4. Strive to improve the practice and the standards

Loading: Loading and Dumping Efficiency

1. Custom design the loading method to maximize loading efficiency by:

a. Maximizing loading rate

b. Minimizing truck/shovel waiting time

2. Use double back-up whenever possible

3. Allow sufficient room for unrestricted maneuvering

Double Back-up

Loading Methods

Double Back-up

Loading Methods

Single Back-up

Loading Methods

Single Back-up

Loading Methods

Loading Methods

Loading Methods

Grazie!!