Cooling the Aggregates
for Batching of Concrete
To prevent 'burning' of concrete when large quantities are poured in tropical climates (construction of roads, bridges, hydro-electric dams etc), water for the batching must be provided in form of ice. In extreme conditions, this may not be sufficient; then the aggregates must be pre-cooled prior to the batching. Cooling is done by sprinkling the aggregates with cold water. Then, in addition to the ice, ice water at 0°C must be provided on the site.
The pictures below show how subcooled ice and 0°C ice water can be produced in one plant. Two North Star M-90CS Flake Ice Makers produce 90 mTon of the ice in 24 hours, which is stored in a 50 mTon North Star Triangular Ice Rake System. A ceiling mounted air cooler (blue, left) keeps the ice storage cold. When the guide plate (yellow) on top of the screw conveyor is flipped to the right as shown, the rake delivers the ice into the conveyor, which brings it to the batching plant. If the guide plate is flipped to the left, the ice flows down to the ice water basin.
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The ice water basin should preferably be constructed below ground level (green in pictures). Wherever available, vulcanic lava can be used as insulation (brown in pictures). Two agitators, one on either side of the basin (right in pictures), stir the water in the tank, to make sure the ice melts and only 0°C water is delivered. Water returning from the cooling of the aggregates enters a mud trap (left in the basin), where sand and dirt picked up by the water along its way through the aggregates is removed. The refrigerating plant - except the ice makers, of course - can also be installed at ground level.If no electric power is available on the construction site, the plant can be powered with diesel prime movers - socalled RPE Units - making it fully indepentent of other sources of energy than diesel fuel.