Shaft 2 Mine Air Heater Facility
This Facility is an air heating system that prepares air at a suitable temperature using the water heating system and provides fresh air to the underground mine. The mine’s air heater facility is a couple of fire-resistant sandwich building with a cast-in-place concrete slab foundation, 12 x 35m axially and 17m high steel structure. The Facility is connected to the Shaft 2 Tower building by 55.8m long, 7.5m cross-section steel air inlet pipe with a cast-in-place linear foundation. There are also two 1.25 MVA substations with a 10.5/0.4 kV voltage to supply power to each air heater facility. The mine’s air heater system is equipped with a 475m3/s f4.5 m axial fan, an 18.5 MW plate heat exchanger, and air heaters in the 2nd heating circuit. It is capable of heating air up to 2°C when the outside air temperature reaches -31⁰C in winter. The construction of the Shaft 2 Mine Air Heater Facility was completed by companies such as GCR LLC, NBIK LLC, and Monadelfus Mongolia LLC according to the design approved by NCCS LLC, over 32 months from February 2017 to October 2019. The Design Author Team of NCSS LLC supervised the construction work during the period and handed it over to the State Commission on October 23, 2019, since when the Facility is in permanent operation.
The boxcut excavation and decline portals
The designs for the Boxcut Excavation and Decline Portals were approved in November 2016 and February 2017, respectively, thus commencing the excavation. They were handed over to the State Commission on October 23, 2019. The main excavation work includes the construction of the main strip in the tunnel, earthworks, conveyor planning, backfilling, and landslide protection. The service tunnel is founded on the 6m wide, 6.1m high, 192m extended metal arches, and reinforced concrete beams. The conveyor tunnel is designed to be 6m wide, 6.1m high, 178m long with metal arches, and reinforced concrete beam foundation. The ground surface protection stockpiles are planned to be located above each 2m high excavation bench.
The construction work was completed Thiess Hishig Arvin GV LLC and supervised by the engineers of the Design Author Team of NCCS LLC.
The Decline Engineering Network – Section 22
The decline consists of two parallel tunnels with three sections, each with a total length of 2,200 m and a slope of 10. 20 m, and a horizontal excavation connecting the two tunnels every 200 m. A tunnel on one side of each section has a conveyor belt for the extraction of ore from the underground mine to the surface, and the other shaft is a service tunnel. The total excavation of the three pairs of tunnels is 16.6 km long. Since this is a long-term project, it is being handed over to the commission in parts.
The conveyor is designed with two motors of 35kV, 5.5mVA capacity and a substation with 35kV 500kVA capacity and another one with 1MVA capacity for each conveyor. The construction of the substation will commence after the excavation is completed. 1×185/35 CU/XLPE/CWS/LSZH/AWA/LSZH cables of 35 kV main power supply are used, and they are designed for the temporary power supply for decline excavations to be built in the substations.
The design drawings of the Decline Engineering Network – Section 22 were approved in 2018. Out of the scope of the approved drawings, 2km long, 35kV main power cable assembly from temporary power station located at the Crosscut 5 until the temporary power station located at the Crosscut 15 was handed over to the State Commission on October 23, 2019, with a temporary power supply of 10.5 kV. The assembly installation was carried out by Thiess Hishig Arvin GV LLC and supervised by the engineers of the Design Author Team of NCCS LLC.