Published in March 2006 Australian Longwall Magazine

Highwall mining in Australia and Indonesia is a reasonably recent introduction, having been first introduced into Australia in the early 1990s. When launched, there was an initial flurry of activity through investments in highwall equipment.

But after a few short years, the introduction ended in tears as the technology failed to live up to expectations. Over the next few years, most of the systems were de-commissioned and remain so to this date. Was it a case of over-promise, under-deliver?

Unlike the Appalachian region in United States’ east – where most highwall applications revolve around contour mining – highwall activities in Australia and Indonesia are restricted to mining the final opencut highwall, where the economic strip ratio has been reached or where physical surface structures have sterilised the coal in the ground. This coal can be reached by creating a trench or from an existing highwall.

As part of the 1990s introduction of the technology to Australia, Superior Highwall Miners witnessed a number of factors that contributed to the demise of the method.

Leading up to the mid-1990s, there were some “extreme labour practices” in the industry, followed by a significant increases in productivity of the labour force through negotiations with unions, introduction of contractors and workplace agreements.

Improvements in productivity and flexibility of mining equipment over that period also made for significantly improved efficiencies.

Although coal prices reduced in US dollar price terms in the latter half of the 1990s and remained at those low levels in early 2000s, the $A/$US exchange rate to a large extent countered the financial impact on most producers.

“These factors contributed to producers focusing their attentions on driving costs down and efficiencies up within their existing environment and therefore did not embrace the new technology introduced by improvements in highwall mining techniques,” SHM general manager Robert Stein said.

So where to from here?

SHM has seen a significant increase in enquiries from producers who do not only see the methodology as a single simple solution, but more importantly, as an additional technique in the overall mine planning process. Many producers have told SHM: “We do not have an immediate need but in two to three years, it is envisaged that we could utilise a machine so please come and see us so that we can start planning.”

SHM said significant increases in opencut productivities are difficult to envisage so excavating into deeper strip ratios will become economically less optimum, thus highwall mining becomes an extremely attractive alternative. In addition, with coal prices being at best steady and the lower quality products in fact declining, operators will be looking for increased margins – where highwall techniques can step in.

Currently some augering is taking place in Australia, however, this is in very limited reserve situations.

SHM is currently discussing a range of applications with potential clients including:

Highwall from trench – in an area in Kalimantan where strip ratios are too high and the cost of highwall mining has proved to be lower than conventional underground mining.

Highwall from trench – coal has effectively been sterilised by waste stockpiles being dumped, 20 years ago, on extremely high value coal.

Highwall from end of open pit – strip ratios are becoming uneconomic and the company still has reserves before reaching the reserve boundary.

Highwall under a pristine swamp area thereby not disturbing the surface area.

“It is inevitable that once we secure an order for one machine in the Asia-Pacific region, additional sales should follow more quickly, as few producers want to be the first cab off the rank, in terms of applying tried and tested technology in the USA environment in the Pacific region where geological and mining conditions are sometimes significantly different,” Stein said.

The SHM highwall miners for Australia and Indonesia will require some modifications compared to the US-based machines, however, the engineering departments in the US and the Netherlands have made significant progress towards finalising these changes, which were based on compliance audits done by two engineers from the Hunter Valley in New South Wales.

SHM also has in-house expertise to help customers to determine recoverable reserves, based on site geology and geotechnical data to help in determining the feasibility of highwall mining.