Is Mining Really Cleaning Up Its Act?

Environmental risks face mining operators, and those living in close proximity to operations, with much publicised acid mine drainage (AMD) problems and knock-on effects for a water table under attack

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Pollution of ground and surface water from AMD, and contaminated dust and soil from mine dumps, have exposed residents living around the mines and on the waste dumps to high concentrations of heavy metals and radiation.

The 2014 Orkney earthquake occurred in a gold mining town in the North West province. Some have blamed mining for weakening natural underground structures. According to a United States geological survey, the earthquake was “severely dangerous” as the epicentre was located near Orkney and Klerksdorp.

Meanwhile, last year SA gave the go-ahead for class action law suits seeking damages from gold companies for up to half a million miners who contracted the fatal lung diseases silicosis and tuberculosis.

The DMR has come under fire in recent times for being too heavy handed, in terms of health and safety protocol, increasing red tape without necessarily reducing the number of fatalities.

To find out more about just how seriously SA’s mining heavyweights are taking the problems, I picked the brains of Dr Henk Coetzee, Specialist Scientist at the Council for Geoscience (CGS), and his learned colleagues at CGS.

How would you rate the level of environmental awareness around sensitive issues facing the industry, with coal mining doing its fair share to damage the image? Is there such a thing as “clean-coal”, and cleaner ways to mine it?

The level of environmental awareness around mining issues is rising, with the industry, regulators and the general public are becoming more and more aware of the environmental risks related to mining. This results in greater pressure on the industry and regulators to ensure acceptable environmental practices and performance. Within the industry reporting standards have become stricter, particularly for multinational corporations. Despite this, there is still room for improvement in practices in the industry.

Much of SA’s coal is produced in large opencast mines. These occupy large areas of land and are reported to degrade the land, which means that land productivity after rehabilitation is not as high as before mining. Coal by its nature has a number of environmental impacts. Coal mining has resulted in large-scale land degradation, and water pollution. Coal burning produces a combination of particulate and gaseous pollutants. Many of these can be managed effectively. However, management of the emissions from coal mining and combustion does create a number of waste products which, in turn, require management. The concept of an environmental footprint or lifecycle is gaining popularity as a way of quantifying the impact of an activity. This process looks at the environmental impacts of not only the activity being studied but also the supporting activities. “Cleaning up” coal mining and utilisation shifts a lot of the footprint from direct discharges to the environment to managed facilities, with their own environmental footprints.

Clean coal refers to a suite of emerging technologies, which mitigate the environmental impacts of coal, including CO2 emissions. Central to the concept is the removal of CO2 emissions using a combination of technologies, including carbon capture and storage (CCS). This is an emerging area of research and development. The CGS is currently engaged in research, in collaboration with local and international partners,on the potential for the application of CCS in SA. Other critical areas for research and development would relate to cleaning up the other environmental impacts of the coal value chain, including water pollution and land degradation.

The use of coal fly ash in the treatment of AMD and as a material for the backfilling of abandoned coal mines has been established internationally. Local research, performed at the University of the Western Cape and the Council for Geoscience, has highlighted a number of potential applications of fly ash in mine rehabilitation.

The Council for Geoscience is also investigating the recycling of coal fly ash and mine wastes into geopolymer construction materials and their applications in mine rehabilitation.

AMD: dangers, new technology to curb, legislation and business commitment?

The dangers of AMD are well known. In an uncontrolled environment, the combination of low pH and high mineral load directly affects the environment as well as placing strain on water treatment and management facilities.

New technologies are being developed, which show great promise and are in various states of development. Treatment costs remain high because of the chemistry of AMD. Removal of pollutants from water almost always involves an input of energy to take a less ordered state — polluted water — to a more ordered state — clean water and concentrated pollutants. This is determined by chemical thermodynamics. All we can improve is the efficiency of the process we use to treat water. There has been a lot done by regulators and mine operators. A self-funding solution remains elusive though.

What is the role of passive vs. active measures in mine cleanups?

Passive measures would be those measures requiring minimal external energy input. Passive treatment technologies are well developed for mine water treatment and work well, within certain limitations. One of the major challenges is adapting passive technologies to work with the large volumes of water discharging from larger mines such as the Witwatersrand’s gold mines.

These techniques use natural processes, such as bacterial reduction, neutralisation with limestone and so on, to remove contaminants. There are definite applications which should be encouraged. The state of the technology is such that they are generally not walk-away solutions and require monitoring and maintenance over a long period of time.

However, when they can be effectively applied they are usually much cheaper than active treatment processes.

What is the role of nanotechnology in mining from an environmental point of view in the future – what positive measures can be implemented?

Iron nanoparticles have been used in water treatment internationally e.g. groundwater remediation, but we are not aware that they have been used for AMD treatment to date. At the CGS we have synthesised iron nanoparticles from commercial chemicals, and we are now working on setting up experiments for testing and developing our process to synthesize them from platinum group metal tailings. As yet, we have no experience in using them for AMD treatment.

Groundwater in SA mining, how can we best preserve what we have already? What are the reserves like, and the quality of water therein? You’ve plotted under the Witwatersrand gold fields, what is the biggest takeaway you’ve learned over the years?

SA has large groundwater reserves. Much of the groundwater is not optimally utilised. In some cases, overexploitation has led to the reduction in yield from aquifers, leading to water shortages. In many areas, available groundwater resources are not used, limiting opportunities for agricultural and industrial development.

In mining areas, underground and opencast mines often intersect the natural water table and may act as a “mine aquifer”. Water qualities vary widely depending on the age of the mine aquifer — over time contamination processes slow down, leading to better quality water. The time frames for this improvement in quality depend on the availability of contaminants, the flow of water and oxygen through the system and the possibility of the development of stratification in a water column within a mine, and can vary from as little as a few years to many thousands of years. This highlights the importance of good characterisation of a mine’s ores and wastes and the hydrological and hydrogeological context within which it exists.

As an example, the Central Rand of the Witwatersrand has multiple zones of ingress along a strike length of more than 40 km — from Roodepoort to Boksburg. The elevation difference between the lowest and highest areas is large, close to 200 m. This means that even if the voids were allowed to flood completely, there would always be a zone where water and oxygen mix with the ore and waste, allowing the generation of AMD to continue for a long time. The complex flow within these voids is also unlikely to allow the entire water body in the underground workings to stratify with clean water floating on denser, more contaminated water.

For the longer term, the idea of preventing the processes which drive water contamination offers a lot of promise. While these won’t completely eliminate the problems, they will reduce the scale and cost of water management in the future. Some of this will require a mind-set change, away from pumping and treating in perpetuity towards more sustainable water management.

What are your insights into recent earthquakes and the effect on mining activity and what is at fault?

It is always very difficult to apportion blame after an earthquake has occurred because there is very little evidence from past monitoring activities, especially before the mining started, that earthquakes are new to a particular area or that they increased in frequency and magnitude, especially in a mining region which started before seismic monitoring. However, the mines are aware of the dangers underground and have implemented very strict safety standards and are also continuously monitoring the seismicity within their shafts. These precautions are paying off, as is evident in the statistics reported annually.

Are you happy with the level of infrastructure development in SA, are we building enough new mines, and are the older deep mines still safe?

The current SA mining infrastructure can be described as being generally good, as corroborated by the World Economic Forum ranking in the top quartile of 144 jurisdictions. However, some mining infrastructure needs improvements as well as further investment to improve capacity. SA has been implementing a comprehensive infrastructure programme, under the judicious leadership of the President of the Republic, His Excellency JG Zuma.

This programme has accordingly been pronounced and led by the President through the Presidential Infrastructure Coordinating Committee (PICC), with its supporting management structures. The government will be integrating and phasing investment plans across 18 strategic integrated projects (SIPs) targeted for the mining industry. There are currently three SIPs that have a particular emphasis on mining-related investment, namely:

SIP 1: Unlocking the northern mineral belt with Waterberg as a catalyst
SIP 3: South-eastern node and corridor development
SIP 5: Saldanha-Northern Cape development corridor
The infrastructure requirements for the development of mining have been factored and given a long time-lag in the development of mining, we are confident that the growth trajectory of the industry is imminent.

The government’s national infrastructure plan is intended to transform the economic landscape of SA, to support the creation of new mines, create a significant number of new jobs, strengthen the delivery of basic services to the people of SA and improve exports.

Peering into the future, what will the mine of 2030 - 2050 look like, and how will the “Internet of Things” affect developments?

Many of the problems we see today stem from not designing and conceptualising mines with sustainability in mind. Environmental management, rehabilitation, water treatment etc. are seen as expensive add-ons to the mining process. In the past, the same could be said for safety. The development of a safety culture and the incorporation of safety into mine design and mining practice is an interesting example to follow. The “Internet of Things” presents some interesting possibilities. The combination of “big data” from multiple sensors throughout a mining process could revolutionise the way we manage mining environments.

A bit off topic, but in your opinion is fracking viable in the arid Karoo?

The most comprehensive information on the exploration for and exploitation of shale gas in the Karoo is contained in:A report that was concluded by the Petroleum Agency SA, Department of Mineral Resources, Council for Geoscience, Department of Water Affairs, Department of Environmental Affairs Department of Science and Technology and the Department of Energy, supported by academics in 2012. 

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