A Doppelmayr ropeway is now up and running at the Buriticá underground gold mine in northwest Colombia, navigating mountainous terrain to transport backfill material from the bottom of the valley to the mouth of the mine.

In October 2017, Austria-based Doppelmayr was awarded the contract to build a 1.4 km long ropeway with material buckets for a transport capacity of 175 t/h. The system was conceived as a continuous bi-cable ropeway, with a fixed tensioned track rope for the material buckets with their carriage to travel on. The buckets are driven by the continuously moving haul rope loop to which they are attached via detachable grips.

The area where the mine, owned by Zijin Mining, is located is mountainous and therefore logistically challenging. The reusable residues of the gold extraction process are used as underground backfill, which is why they must be taken from the bottom of the valley to the mouth of the mine at 1,700 m above sea level, thereby covering a difference in altitude of approximately 646 m. What would be an arduous and long journey for trucks, with plenty of exhaust emissions, becomes a swift and efficient job if a material ropeway is used, Doppelmayr says.

To allow for the haul rope to be run at a constant speed, the buckets are detached from the loop in the stations and slowed down before they are loaded via a chute. Once a bucket has been filled, it is accelerated to running speed again and re-attached to the haul rope before leaving the station.

In the unloading station, the bucket is once more taken off the haul rope. At the designated unloading point a special mechanism unlocks the latch on the bucket, the bucket is tipped, and the material is safely transferred onto another chute. The bucket then returns to its original position. It is locked again and re-attached to the haul rope before travelling back into the valley empty.

In the past, continuous bi-cable ropeways have often been used for material transport applications, the company explained.

“For the Buriticá project, Doppelmayr’s engineers have revised the design and mechanics of continuous bi-cable ropeways from scratch and optimised it for the transport of material in buckets,” it said. “The system complements Doppelmayr’s portfolio of material transport solutions.”

Put into service in February 2021, the solution has a transport capacity of 175 t/h of gold residues, a running speed of 6 m/s, and comes with 20 carriers and one tower.