CMOC-Northparkes Mines, located 30 km northwest of Parkes in New South Wales, has successfully taken its Lift 1 North (E26L1N) project into production. The Lift 1 North Project has taken 37 months from the approval on January 1, 2019 to the commencement of production on March 1 2022 which was an impressive five months ahead of the feasibility plan. The company says it has “challenged the impossible” and delivered an outstanding result.

The project has established a significant ore source – over 40 Mt of copper-gold ore – ready to supply the ore processing plant for the next decade. E26L1N is a block cave extension, mining the porphyries to the north of the E26L1 and E26L2 caves. Northparkes is known as an innovative operation – it was the first in Australia to use underground block caving, starting in October 1993 with the construction of the E26 underground block cave mine. In 2015, Northparkes also became one of the world’s most automated underground mines achieving 100% of production from automated loaders, using six Sandvik LH514 units operated from surface.

Northparkes is a joint venture between China Molybdenum Co Ltd (CMOC, 80%) and the Sumitomo Group (20%). The Lift 1 North Project has been delivered at a cost of A$249 million. When compared to the A$350 million it cost to construct the E48 block cave 12 years ago, which was of a similar size and design with 10 extraction drives, crusher and conveyors. Pictured are the mine’s Managing Director Jianjun Tian and Mine Manager – Rob Cunningham at the ribbon cutting ceremony recognising project completion.

The project involved 11 km of underground development in the extraction and undercut levels as well as conveyor drives, drilling and hydraulic fracturing (hydrofracturing) of the orebody, underground poured and precast concrete roadways, an underground ~1,000 t/h direct tip jaw gyratory primary crusher, two new conveying systems and associated infrastructure. At the peak of construction, the project employed up to 180 people, which included a mixture of employees and contractors. It also included an upgrade to the ventilation system which has provided the new E26L1N mine with sufficient air flow to support development and production activities. The ventilation project involved two raisebored shafts to a maximum depth of 588 m. The project also involved construction of a surface exhaust fan station and shaft lining both shafts. Local company JTMEC carried out the E&I installation of the new jaw gyratory crusher, new transfer conveyors, secondary and primary ventilation system installations as well as new workshops, lubrication bays and wash bays.

The E26L1N operation has also been designed to utilise an increased level of automation and digitisation, helping to deliver a safer and more productive mine including the establishment of an automated production loader fleet and ancillary equipment required for the ongoing operation. Back in 2015, Northparkes became one of the world’s most automated underground mines achieving 100% of production from automated loaders, using six Sandvik LH514 (five electric and one diesel) units operated from surface and utilising the AutoMine Fleet system. They travel at up to 21 km/h with cycle times of 3 to 4 minutes. The automated loaders saw a 23% productivity increase per unit per day over manned loaders.

Northparkes is known for having developed its own unique extraction level layout that locates the material handling system, including crusher, to the side of the extraction level, thereby alleviating the need to construct a third level dedicated to haulage. Similarly, it has established the extraction level as the primary ventilation level, thereby eliminating development to support mine ventilation. The undercut level, which is used to initiate caving, is 14-20 m vertically above the extraction level, the height being dependent on the undercutting method. Undercutting, which involves sequential firings of overlapping fans of blastholes to create the initial void for caving, is the rate controlling step for production ramp-up, controlling both the rate of undercutting ore and the start of production from drawpoints.

thyssenkrupp worked with Northparkes on a new double mouth jaw-gyratory crusher for the Lift 1 North mine

Mine access for all personnel and equipment is provided by surface portal and decline. The decline has a standard 5 m wide by 5.5 m high arched profile. The hoisting shaft represents the second means of egress and the ore skips can be fitted with a man-riding cage in the event that personnel cannot egress the mine via the decline. The mining process involves recovery of broken rock from the drawpoints by 14 t capacity Sandvik LH514E electric LHDs, which tram the ore to a primary crushing station located on the margin of the extraction level.

Crushed ore is fed onto high-speed inclined conveyors via an ore pass that also provides storage capacity. Ore is conveyed to the underground loading station, which consists of three ore passes feeding the hoisting system. The hoisting system consists of a ground-mounted friction winder with integrated drum and rotor, servicing two 18 t payload skips in counterbalance, running on rope guides in the 6 m diameter concrete lined shaft. Hoisted ore is transferred via an overland conveyor to crushing cicuit located. The underground and surface material handling systems and ore processing equipment have also been upgraded to achieve an expanded nominal throughput rate of 7.6 Mt/y.

The new crusher is noteworthy as the world’s first “double-mouth” jaw-gyratory crusher, developed by thyssenkrupp Industrial Solutions in consultation with Northparkes to meet its specific operating objectives. It is based on the proven BK 63-75 design but has a new, patented, spider to give the opportunity to feed the crusher from both sides – the double mouth jaw configuration – thus removing the need for a primary crusher feed (buffer) hopper and primary apron feeder. This dramatically reduces excavation requirements in an underground operation like Northparkes leading to a sizeable reduction in installation cost. The ability of this crusher to handle a very large feed size and a high reduction ratio has also negated the need for the use of a pre-screening grizzly.