Abandoned mines unlock hidden treasures

An innovative Monash University study has proposed the Mining Incidence Documentation and Assessment Scheme and quantified Australia’s 80,000 active, inactive and unrehabilitated mines to show the value opportunities of rehabilitation and reuse that may be hiding in the dirt.

As the mining industry sews the seeds of fortune for Australia’s economy, it is important that it understands the ways that the environment and local communities may be impacted.

These social responsibilities are increasingly recognised by all active mine sites in Australia, which are required to have progressive rehabilitation plans in place.

This was not always the case, with thousands of abandoned sites across the country lying dormant for decades.

Approximately 80,000 inactive mines are littered across Australia, with 19,000 of those located in Victoria.

Many are from Australia’s gold rush that started in the 1850s – long before the introduction of progressive rehabilitation during a mine’s life cycle.

While the economic benefits of the gold rush can still be felt today, having kickstarted the development of cities like Melbourne, issues including dust pollution and waterway contamination remain an issue still being solved today by state governments.

A team of researchers at Monash University, led by the university’s associate professor of the resources engineering of the Department of Civil Engineering Mohan Yellishetty, has compiled a study that shows that Australia’s abandoned mines have the potential to become assets rather than liabilities.

As an expert in sustainable mineral resources, Yellishetty has experience at Monash University, CSIRO and Yale University.

The team’s research paper, A Geospatial Database for Effective Mine Rehabilitation in Australia, identified abandoned mines across Australia Geographic Information System (GIS) to quantify the data. It is part of an ongoing study from Monash University to provide a spatial analysis of mines globally.

“The important findings of this study are there’s a bit of inconsistency among states in Australia in terms of how they report abandoned mines, and secondly there is no real national-level database set up for rehabilitation,” Yellishetty tells Australian Mining.

“Some states have broader rehabilitation programs compared to other states, so we are far behind compared to our counterparts in Canada or the US.”

Yelilshetty and his team based their research on the Canadian National Orphaned/Abandoned Mines Initiative (NOAMI) framework to classify abandoned mines as either active or inactive sites.

This was followed by the Mining Incidence Documentation & Assessment Scheme (MIDAS) scheme to catalogue and compare active or inactive mine data without specific reporting conventions.

“For inactive, we’ve got terminated, negligent, maintenance, rehabilitated and heritage (mines), so from our estimates, what we found is close to 80,000 inactive mine sites exist in the country,” Yellishetty says.

A wide range of rehabilitation and reuse opportunities have been identified by Yellishetty’s team, including critical minerals’ extraction, construction works, tourism potential to rehabilitated sites, carbon farming, renewable energy generation, overburden waste to create building bricks and ceramic products, and recycling facilities.

Using the research team’s GIS, the facility that a mine will be rehabilitated into can be determined by factors such as its proximity to farming areas.

Yellishetty is also a co-founder of the Critical Minerals Consortium, which provides advice to assist policy makers on minerals criticality and opportunities to reduce criticality through the development of domestic supply.

“There are numerous ways which (abandoned mines) could be brought to life. For example, one of the areas that we are currently engaged in is the Critical Minerals Consortium,” he says.

“We wanted to see if some of these abandoned mines have the potential for critical minerals extraction because critical minerals are often companion metals to base metals such as copper, nickel and zinc. Critical minerals can sometimes be found in fly ash (from the burning of coal) and tailings from alumina and other refineries.

“For example, if you’re mining for copper, a number of other critical minerals are part of that ore complex.

“We want to explore some of those options as well, alongside looking into some tourist attractions and also looking at electricity production potential. If you have two adjoining abandoned mines with some elevation difference, pumped hydro could be a potential option there.”

Principal consultant at Whittle-DG and researcher (Minerals Criticality Assessment) at Monash University David Whittle has been assisting the research team in its study.

With a wealth of experience and previously serving as BHP’s senior manager for resource planning and development, he co-founded Monash University’s Critical Minerals Consortium.

Whittle says there are many factors that require the effort of both the industry and government bodies to rejuvenate these mine sites.

“Some of the thinking that’s been driving (Yellishetty’s) work is to look at not only where you can spend money to make things better, but where you can find opportunity to make money and also make things better,” he tells Australian Mining.

“There’s a whole lot of fairly complicated factors that go into determining these things.

“Since this paper has been published, we have been approached by a quarry company that signed a deal to take some additional research in repurposing a quarry that will close at some time in the future.

“We’ve also had a strong enquiry from water companies who are indeed looking at how can we use these quarries, and the study hasn’t been done for them but we’re still in discussions.”

During Whittle’s time at BHP, he was involved in mine closure planning, which he says has become a challenge within the industry.

“If people think quarry and mine planning is difficult, they ought to try closure planning,” he says.

“Closure planning is significantly more difficult partly because you’re planning to do something 10 or 20 years in the future, and it’s very difficult to know what the conditions will be like, what community expectations are going to be, what the government expectations are going to be and what new knowledge you’ll gain about the area and the mine between now and when it is actually closed.

“Most good closure studies are actually continuous research and development studies and they take considerable time and investment.”

Taking initiative

Glencore has received government certifications for several of its mining rehabilitation efforts across Queensland and New South Wales.

The mining powerhouse has completed progressive rehabilitation of over 1300 hectares of mined land.

“Glencore has also received Queensland and NSW Government sign-off (certification) for areas of this work in each of the past four years,” a Glencore spokesperson tells Australian Mining.

“Earlier this year, our Westside open cut mine in the Lower Hunter region of New South Wales achieved certification for 38 hectares of rehabilitation, a first for the state’s coal industry under contemporary mine rehabilitation criteria.

“In 2019, our Rolleston open cut mine achieved certification for another 166 (hectares) of its rehabilitation in central Queensland.

“Rolleston now has sign-off for almost 400 hectares of rehabilitation (equivalent to nearly 670 football fields), which represent almost 40 per cent of the total amount of mined land that has been rehabilitated at the site since operations began in 2010.”

Glencore’s Liddell open cut mine in the Upper Hunter region of New South Wales started a six-year trial in 2012 to show cattle grazing could be sustained on rehabilitated mining land.

“In part, the trial responded to criticism from some sections of the community who did not believe that land that (had) been mined for coal could be rehabilitated to sustainable grazing land,” Glencore states.

This feature also appears in the December edition of Australian Mining. 

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