Cadia East – Newcrest’s new gold mine

The Cadia East gold mine, Aus­tralia's largest new under­ground operation, has officially opened.

The mine is part of Newcrest Mining's wider Cadia Valley Operations near Orange.

Cadia East has been developed as a large underground panel cave gold mine, and is the first of its type in the country.

Once it reaches full operational capacity in 2017, Cadia East will also be the largest hard rock underground mine in the country, and one of the largest in the world, producing 27 mtpa.

This will take the Cadia Valley Operations total production, which includes the Cadia East and Ridgeway mines, from 447,000 ounces a year to 700,000 ounces a year, rivalling other massive mines including the Super Pit and Boddington.  

Newcrest has invested around $2 billion to develop the first panel cave and the expansion of processing facilities on site.  

Commercial production from Panel Cave 1 commenced in January last year, with the development of the second panel cave currently underway and due for completion in 2015.  

Hosting a mineral resource of 2.8 billion tonnes, made up of 37 million ounces of gold and 7.5 million tonnes of copper, the mine will have a life of 30 years and support an expected 1900 direct and indirect jobs.

And with an all-in sustaining cash cost of just $381, Cadia East is set to be the envy of gold mining operations nation-wide.  

Speaking at the official opening of the mine, Newcrest CEO Greg Robinson said Cadia East was a long-life asset and a "cornerstone of our company's strategy".

"Cadia East is at the forefront of innovation and is of international interest," he said.

"Through extensive planning and teamwork, we have built a highly efficient, low cost mine more than 1.2km under the surface. We have continued to utilise the latest technology and challenged ourselves to improve bulk underground mining methods along the way."

Technology advanced/leading edge of bulk caving  

The innovation Robinson referred to includes the bulk caving mining method Newcrest has employed at the site.

Seen as a cheaper alternative to other mining methods, Newcrest said it is at the forefront of implementing unique technologies, and has people working at Cadia East that are considered experts in the field.

General manager at CVO, Tony McPaul, said block caving at its Ridgeway mine gave Newcrest the chance to perfect the technology before applying the method at Cadia East.  

And with the orebody at Cadia East perfect for its adoption, early work went into ensuring the proposed ramp up could develop as planned.

This included preconditioning with hydraulic fracturing, blast preconditioning, and an extensively blasted undercut to ensure the ore body is fractured at the correct points for caving.

At Cadia East the undercut sits 20 m above the extraction level, and is created to initiate caving. The undercut is made up of hundreds of drawbells and drawpoints which funnel ore to a point for collection, and is drilled and blasted progressively to create a cavity into which the overlying ore can cave. This helps to initiate caving in the above ore body.

Ore is then dug from the bottom of each drawbell and delivered to a massive underground gyrating crusher, for resizing and delivery to the surface for processing.

"We use the stress from the cave to help break the rock," McPaul explained.  

"So we do all the preconditioning and then as you develop the undercut level it will determine where the stresses go in the rock and that stress then starts to break the rock up and starts the caving method.

"We have seismic monitoring gear set up around the mine so we can watch where that seismic activity is and change where we are undercutting to use that stress level to break the rock.

"All you want to do is make sure the rock starts to cave."

McPaul said Newcrest has worked with block caving partner company Codelco to develop the technology to be efficient as possible at Cadia East.  

The company also shared experiences and learnings with other companies and "picked the best of what we've seen from our peers and consolidated it into what we see as best practice in block caving".

This includes sharing information with nearby China Molybdenum-owned Northparkes mine, which also uses the block caving method.

McPaul said Newcrest had worked on being at the cutting edge of the bulk mining technology innovations and said Cadia East can take credit for "pushing the boundaries".  

"We're ramping Cadia East up faster than anybody else has ramped up a bulk underground mine anywhere in the world," McPaul explained.  

"Everybody is watching us and seeing how we do it, so we can safely say we're leaders there.

McPaul said he is confident the method will continue to be a success and credits the implementation of the technology to his workforce at the mine, some of which have been on the journey to see Cadia East come to life for over ten years.  

Automation and the Site Operation Centre  

In the same way the Ridgeway mine paved the way for the implementation of innovative bulk mining methods at Cadia East, it has also seen the development of automation which will be transferred to the new complex.

  Leigh Cox, projects general manager at CVO told Australian Mining that if Newcrest had learnt anything about the automation process, it was not to go gung-ho right away.  

To this end the company has opted for a staged approach at Cadia East, testing differing methods before fully implementing them.

A successful example of this are the semi-automated boggers at Ridgeway which work to take ore from the undeground drawbells to crushers.

Cox said if you go underground at the mine, you can see them 'zipping' around unmanned.

The boggers do need help to load mined ore, and when it's time for this, the machine sends an alert to the operator in the Site Asset Operation Centre (SAOC) who takes over to help it along.  

Cox said while the machines don't yet have the ability to load themselves, they can be directed to any part of the site as specified by the operator in the SAOC and re-routed to change directions and go anywhere within the mine.

Not only does this reduce costs associated with hiring drivers, but also increases safety underground as hazards related to workers and machinery coming into contact are minimised.

This is a theme common at the SAOC, where TV screens, graphs and data are used to make mining decisions.

SAOC operators monitor equipment and machinery located on the surface and underground to ensure optimal efficiencies, as live video from across the site is streamed to individual monitors, allowing many areas to be viewed at the same time.

Operators communicate with personnel on the ground via radio and phone, advising if any changes to the mine plan need to be made.

McPaul said this means operators are taken out of working in silos and can instead communicate with each other side by side to ensure to efficient and safe running of the mine.

 "The SAOC delivers significant operational efficiencies and also improves safety outcomes," McPaul said.

"If I want to know something, all I have to do is go to SOAC because every part of the operation is being controlled from there, the desks are sitting side-by-side, so the operators can talk to the next person and that's a big advantage."

When Australian Mining asked the superintendent on duty if operators missed working on the field, the answer was a resounding "no".

"It's clean and warm here with no dirt or dust," he said.

But you don't necessarily need a mining degree, or experience, to work at the centre, with cleanskins trained up at the site.

McPaul said people who are good with computers and willing to learn are encouraged to apply.

People and the community  

"As far as hard rock mining goes, you probably don't get a better location than this. But it does mean we have lots of neighbours and lots of environmental conditions," McPaul said.

The mine has around 1000 environmental conditions it must adhere to, and McPaul said the company has worked hard to build a relationship with people in the local community.

"We're very proud of the relationship we have with the local community," he said.

"This doesn't mean we agree with everybody all the time and it doesn't mean they agree with us all the time, but when we disagree, we can have that disagreement and still get along at the end of it."

As part of this, the Community Consultative Committee provides a forum for open discussion on issues directly relating to the company's activities, environmental performance and community relations and works to keep people informed.

The meetings provide data around air quality monitoring, noise, blasting, traffic, environmental management, and rehabilitation as well as transparency around any exceedances or potential issues.

"The community in which we operate is fundamental to our ongoing success. We don't take their support for granted and we are committed to building on the strong relationships we have with them," McPaul said.

Continuing with the theme of transparency, CVO holds an open day annually, with more than 3000 people streaming through the gates to take a closer look at the mine.  

"It's a way to engage the community and show them what we do," McPaul explained.  

In light of the success of these tours, CVO may also become a wider tourist attraction, with plans underway to build a tourist centre and lookout at the top of its closed open pit.  

"It will be a place where residents can bring their family and friends from outside of the area to have a look at where they work and they feel quite special about being able to do that," McPaul said.

And with a mostly residential-based workforce, the company said it is committed to hiring locals to its ranks.
McPaul said the seeds of a number of apprenticeship and training programs are starting to bear fruit with recruits starting five years ago now undertaking more senior roles on site.

"The biggest advocates in the local community are our employees," he stated.

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