Hunter Valley Operations is one of the largest coal mines in New South Wales, today producing around seventeen million tons (mt) of high quality thermal and semi-soft metallurgical coal a year to help the world meet its energy needs. But the historic mine site, which first started operating in 1949, has ambitious plans to increase its annual production rate further, to twenty-one million tons of raw coal annually.

To achieve its goal, the site has transitioned away from dragline excavators that traditionally moved most of its waste material, parking up the last one for good in September 2023, to a new fleet of truck and shovel excavators.

HVO now has eleven new Hitachi machines that it's using to shift the bulk of its growing operational waste volume: six EX5600 - 600-ton class excavators and five smaller EX3600 - 400-ton class excavators.

David Foster, General Manager at Hunter Valley Operations said HVO chose Hitachi machines because of the site's positive experience over the past 15 years using a smaller Hitachi fleet, which cemented their reputation for being reliable and cost effective.

"Hitachi machines have always been great for us, and with this new fleet we get not only the historic reliability, but an upside in productivity because they have slightly bigger buckets and a bit more power and capacity enabling the trucks to be loaded faster," he said.

The newest model from Hitachi's long history in the 600-tonne class, is the Hitachi EX5600-7, of which HVO has five. It has a maximum digging depth of 4,800mm and an operating weight between 541 000 - 553 000 kg. The 36.0 m³ capacity bucket has been specifically designed to enhance loading capability with a tilt angle that enhances operational efficiency. In the truck, a multi- functional display provides key machine information and performance indicators.

The EX5600-7 also features new electronically controlled hydraulic pumps, optimized cooling package and enhanced hydraulic circuits, for unparalleled performance and efficiency. In addition, it's designed and built with improved pathways and handrails for a safer and more reliable machine.

The EX5600 model is a prime example of how Hitachi listens to its customers and integrates into its new machines the features they want, according to Foster. "We have a good relationship with Hitachi because they listen to their customer, they're developing a product that meets our needs. The relationship they maintain with their customers is certainly really important to us," he added.

The smaller EX3600-7 is also designed to deliver exceptional around-the-clock performance while optimising consumption and taking productivity to a new level. It has many similar features to EX5600-7, but with an operating weight of 365 000 - 366 000 kg and a backhoe Bucket capacity of 24 m³.

Ramping up coal production at HVO

The new Hitachi machines will also support HVO's wider expansion plans. As well as ramping up production, the mine, which is owned by a joint venture partnership between Yancoal and Glencore, is also seeking government approval to expand its operations until 2050.

If the expansion is granted, the mine site, which comprises HVO North and HVO South and is located in Lemington near the NSW Upper Hunter town of Singleton, going forward will become one of the longest running coal mines in the region.

Work to expand production at the mine involves moving back through the coal seams previously mined, going much deeper to remove more thermal and semi-soft metallurgical coal.

This is only commercially viable because of advancements made in excavator size and performance, said Foster. Thirty or so years ago, using the smaller machines, it would not have been financially feasible.

The new Hitachi excavators chosen for the job have been integrated into HVO operations over the last few years. They will enable the operator to move much more waste more quickly, helping it reach its goal of twenty-one million tons of raw coal total volume material in just two years' time. They were also chosen as they are particularly suited to tackling some difficult areas at the mine site.

The machines are already delivering an increase in production, according to Foster. Historically around 100,000 billion-cubic-meters (bcms) of waste per year were moved from the mine. Two draglines moved approximately 40,000 bcm of this material. Today, around 120,000 bcm of waste per year is being moved through the truck and excavator fleet only.

"The trucks are enabling an increase of 20% and offsetting the previous 40% of material that used to be moved by the draglines, meaning, all in, the excavator fleet over the last couple of years has helped double the mine site's capacity," explained Foster. "Obviously, when you get a productivity increase, you also get a cost benefit and that's mostly what we're all about, driving as low as possible cost as we can," said Foster.

Hitachi equals high reliability

Hitachi has helped train HVO staff to use the fleet through its onsite staff training programme, making sure maintenance teams are aware of any new changes. But the machines are now easier to maintain adding to the lower overall operating costs.

HVO is expecting another delivery of a Hitachi excavator, the EX5600, in around 18-months' time as part of its reinvestment plan into the business over the past four-five years. This will be ongoing as it continues building towards its twenty-one million tonnes of coal per year goal, with more purchases of Hitachi machines required along the way, according to Foster.

"It's always difficult deciding what excavator machines to go with, but at the end of the day, for us, it comes down to cost and Hitachi machines are extremely reliable and have a good record here at HVO. Once you get a machine on site, and your workforce is familiar with the operation and the maintenance of those machines, it makes sense to continue to invest in them," he added.