Platecoil® in Mining Operation

A major gold mining operation in South Africa required cooling water for its equipment, and refrigerated air throughout the mine. Due to the depth of the mine, rock wall temperature reached 120°F. If refrigeration was lost, all 6,500 miners would have to be brought to the surface immediately.

Platecoil® Benefits

Technical specialists at Tranter’s Texas Division designed a special shallow pass plate, banked in a 35-plate cooling module, to satisfy the mine’s specific requirements. Dies were built to press the plates, and fatigue testing was performed to verify the unit could withstand the pressure variations inherent in the operating cycle. A sample coil was exposed to over 1.2 million cycles from 30 psig to 75 psig, and it did not leak.

The 48” x 150” Platecoil plates were constructed of 16/16 gauge 304LSS, and furnished with a passivated finish. The mine used eight 35-plate modules.

About the Operation

Liquid ammonia refrigerant enters the coils at the bottom at approximately 18°F. The coil floods with liquid refrigerant while water cascades over the outside surface of the plate. The water causes the ammonia to evaporate, which exits as a gas at the top of the coil. Ice builds up on the outside surface to a thickness of approximately 5/16” in about 15 minutes.

Ice is harvested from the plate by stopping the flow of liquid refrigerant and introducing hot ammonia gas into the top of the coil. The hot gas allows the ice to release from the Platecoil unit in sheet form.

Other Potential Applications

All types of mining and any other operations where ice making is used to supply refrigerated air and cooling water for equipment. This concept can also be utilized as a falling film cooler for low-temperature chilling of liquids.