Ernest Henry Mining in north-west Queensland has transitioned from an open pit to an underground sub-level caving operation late last year, with Xstrata utilising Elexon’s Smart Marker technology to maximise ore recovery, while reducing dilution.
The Smart Marker system is a blast resistant, long-life radio frequency identification (RFID) device, which has the ability to measure ore flow electronically, in particular in sub-level and block caving operations.
Xstrata Senior Strategic Planning Engineer Alex Campbell’s role involves overseeing the caving and geotechnical aspects of the cave start-up and the transition to underground mining at the copper, gold and magnetite mining operation. “We recently started using the technology as of last week [end of November], and have installed the Smart Markers within the crown pillar between the underground and open pit operation,” he says.
The blasted ore material within the crown pillar forms an ore blanket above the sub-level cave. The purpose for installing Smart Marker system in this region is to track the flow of ore and to identify areas of potential dilution. The data from the Smart Makers can then be used to adjust the mine’s draw strategy to maximise ore recovery, while minimising dilution and ultimately improving the company’s financial return.
A second Smart Marker system will be used at the mine in 2013, to assist in characterising the flow properties of the sub-level cave blast rings, Campbell says. “The main things we are trying to focus on include, characterising width and depth of draw, as well as primary, secondary and tertiary flow behaviours over multiple levels.” The system will also assist to determine drill and blast performance including the back break and apex recovery, which has an impact on overall cave flow.
Xstrata has invested $A589 million to extend the life of its Ernest Henry operations by at least 12-years. The Smart Marker system allows the team at Xstrata to better understand what is happening inside the sub-level cave. Campbell says, like all caving operations the goal is to maximise ore grade and recovery, while minimising dilution within the geotechnical constraints of the operation.
At the moment, Xstrata are trucking ore from the underground mine via a decline at a rate of about three million tonnes per annum. This is expected to ramp-up to 6Mtpa once the hoisting shaft is commissioned in late 2013. The technology is currently being used at mine sites around the world. In Australia the technology is being used at Newcrest Mining’s Cadia East operations, as well as at Rio Tinto’s Northparkes operation in New South Wales, to name a few.
Meanwhile, Campbell says Elexon’s reputation in Australia, is one of the reasons Xstrata engaged the mass mining technology specialist. “The company’s technology is easy to use and track, plus the process involved with collecting the data is quite simple,” he says.
Elexon is also involved in the Mass Mining Technology research group, which is headed up by mining engineer and Professor at the University of Queensland Gideon Chitombo. “Having individuals with their expertise based in Australia is very helpful when it comes to customer service, and getting people out on site to assist with the installation and use of the technology,” Campbell concludes.