The use of a non-rotating rope for the miracle rescue in Chile

The amazing rescue of the 33 workers from the San Jose mine in Chile has finally been brought to a successful end. During their ascent in the rescue capsule, the lives of the trapped miners depended on a special rotation resistant, compacted wire rope. Time was a major problem for all rescue activities. Therefore the drilling procedure was done without lining the bore hole. The rope used was a 1,000 m long non-rotating strand compacted type with a polymer covered steel core (EVOLUTION TK 16) [1]. Because of the un-lined bore hole, rotation resistance was absolutely necessary to minimize rotation of the capsule during the rescue. Further the bore hole was not straight. This circumstance generated severe rope – rock contact. Highest abrasion resistance of the rope was required to work properly under these conditions. The winch was a 6 tons winch with a maximum speed of 4 m/sec. The rope diameter was 24 mm. The lifting height was almost 700 m. So there were a lot of layers on the drum. Perfect multi layer spooling behaviour in combination with a smooth jump from layer to layer to reduce the shock in the capsule was an additional requirement. Very small sheaves had to be used at some special positions. D/d ratios lower than 15 guided the rope which lead to additional concerns of the resistance against bird caging.

Author(s): R. Konrad and R. Traxl