Coal Mining Equipment

Coal mining have present in the mining industry since the man needed to obtain energy sources. The equipment employed in concentrate and recovery coal has suffered some changes and must be mentioned that each piece of separation equipment used in coal recovery has a specific range of applicability in terms of particle size. Consequently, determination of particle size and techniques for its control are very interesting parameters to be considered at the moment of selecting any equipment.

The separation used in coal is based on variation of size and compositions due to most minerals have different properties depending on their size or composition, they can be influenced by varying degrees at the moment of applying any mechanical force. Separation is brought by suspending particles in a medium and passing the suspension through an appropriate piece of equipment.

Mining equipment to concentrate coal is selected considering three aspects: properties of minerals in the deposit, type of separation process, and requirements of production. The flowsheet chosen for each coal ore must be based on the type of separation method more effective. In order to do this will be necessary to consider the characteristics of the final product, economical aspects influenced by the coal content, size of the mill, and location.

The main equipments employed in coal beneficiation have been heavy media vessels, jigs, spirals, and flotation machines. The first three equipments have been used to recover coarse coal, and flotation has been used to recover fine coal.

The heavy media vessels are related gravity concentration and a special medium which marks the difference between heavy and non-heavy minerals. The objective is to obtain two products: one floated and other sunk.

Spirals have evolved over the past forty years and have made possible better operation with higher percent solids. It can be done by mechanically fostering interactions between particles. Spiral are designed considering the particle-particle interaction with the double objective of maximizing the period of initial acceleration, which should follow a collision in which a particle is brought to a near complete stop, and making use of the ability that small particles have to settle between large ones, this can be done by operating at higher percent solids.

In a jig, the optimum condition of having the flow velocity reduced to nil, while maintaining the fluid condition of material trapped by riffles is achieved. The pulsating action of the jig lifts the entire bed of particles off the screen surface. As the stroke reverses, the bed tends to fall bottom layer first, next layer next, and so on. This dilation of the bed effectively fluidizes it so that the high specific gravity particles can sink through it and be concentrated.

Floation have used in coal recovery for many years. Before the usage of fully mechanized coal mining, the larger coal used to be taken but the coal finer were left as tailings. However, today, factors like need of energy, high cost of coal prices caused new methods to be applied to gain finer coal. Another reason of coal flotation is the environmental aspect. Today, because of the environmental laws, the coal can’t be driven out before a washer unit. So, for about twenty years new methods and technologies are being developed in the coal-cleaning unit.