Basic components of a batch plant unit

Aggregates and reclaimed asphalt, if used, stocked in piles, are placed in cold feed holding bins using a loader or a truck. The number of cold feed bins is usually from three up to nine, depending on the number of different size aggregate used and hourly production output. 

In certain models, the bins, particularly those of fine aggregates, are equipped with a vibrating system. This eliminates the development of caves within the bins when aggregates are damp during discharge of aggregates to the conveyor belt. 

The feeding unit consists of a system of conveyor belts, or elevators, which, in modern plants, are able to change speed and thus vary the supply of aggregate to the heater drum. 

The proportion of coarse, medium and fine aggregate flown onto the feeding system is similar to that determined in the mix design, preventing excessive overflow of a certain hot bin. 

The role of the drying and heating system is significantly important, given that the amount of water (moisture) usually contained in the cold aggregates should be removed within a short period and the aggregate should reach the appropriate temperature to be coated with bitumen. 

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