Working towards zero waste

WASTE MANAGEMENT

Working towards ZERO WASTE

The mining industry is one of the biggest contributors to waste in South Africa. The industry is mindful of this fact and is continuously working on implementing waste management strategies that will not only manage mine waste, but also reduce the amount of waste produced. By Dineo Phoshoko

The mining sector is in need of solutions that can shift and boost it to regain its competitiveness and become a key contributor and driver of economic recovery in the wake of the pandemic. Appropriately managing and minimising waste is among the industry’s key interventions.

Dave Morrey, general manager, EnviroServ, explains that there are three main categories of mine waste in volume. First, there is overburden, which is waste that consists of soil and rock that needs to be removed in order to get to the ore deposit.

The second category of waste is tailings, which is waste that remains following the extraction of valuable product from the ore. Tailings dams are also included in this category. Such dams are used to store waste produced during the process of extracting the valuable product from the ore.

The third category of waste is slag, which is what remains following smelting or refining processes in mining.

The three categories of waste above are generally managed within the mine itself. There are other types of waste, though, such as hazardous waste from maintenance and processing activities, laboratories, spillages, waste tyres, food waste and general waste. In addition, Morrey adds that contaminated rubble resulting from contaminated demolished or refurbished plants also counts as waste.

Dealing with mine waste

Different waste types are dealt with differently. Hydrocarbon waste contains elements of oil, diesel or petrol. This often occurs as a result of spillages or leaks – which can happen anywhere on the mine site. A bioremediating method is used to dispose of hydrocarbon waste. The approach entails using soil isolation products to treat the spillage area. Such products contain microorganisms that break up the carbon in the affected spillage area, leaving it free of hydrocarbon contamination. Sawdust and other flammable materials were traditionally used to clean up highly combustible hydrocarbons. This is not only ineffective but also potentially hazardous. Some mines and municipal by-laws prohibit their use. Leading adhesives, electrical terminations and mineral products producer Pratley supplies solutions that are effective, non-flammable and eco-friendly.

If the waste cannot be disposed of through bioremediation, it is transported to a compliant hazardous treatment facility. It is not uncommon for samples of waste in this category to be tested at a laboratory to identify the extent to which the waste is contaminated with hazardous chemicals. Another method of identifying the extent of hazardous chemicals present in waste is through a local soil analysis. It is important to be mindful of the quantity of hazardous chemicals that are present in waste to ensure that they are within the threshold limits and adhere to the regulations and permit requirements at the point of treatment or disposal.

Old tyres from mine dump trucks also contribute significantly to waste production. Albi Modise, chief director: Communications at the Department of Environment, Forestry and Fisheries (DEFF), explains that the process of disposing of waste tyres involves their collection from mainly fitment centres and mines (where tyre waste is generated), temporarily storing the tyres at waste tyre storage and pre-processing facilities, and recycling and/or recovering energy at various tyre processing facilities, which include cement kilns, crumbing facilities and pyrolysis plants, among others. “The processing facilities are supplied with whole tyres and/or pre-processed tyres (i.e. shred or cut tyres),”

WASTE MANAGEMENT

Modise says. Previously, the DEFF’s Waste Bureau used to have an industrial waste management plan that was responsible for collecting and disposing of the tyres. A levy fee was included in the price of tyres, which was then paid to the Waste Bureau for collecting and disposing of waste. Some mines have an agreement with a service provider that collects old tyres when delivering the new ones.

According to Modise, currently, there is no approved tyre Industry Waste Management Plan. “The Waste Bureau is currently managing the waste tyre operations until a new plan is approved by the minister in line with transitional arrangements in the Waste Tyre Regulations. The CSIR is currently developing a new plan,” he explains.

Understanding waste management

According to Morrey, most mines with valid mining licences have a good understanding of what is expected of them in terms of waste management. He adds that the National Environmental Management: Waste Act (No. 59 of 2008) also stipulates the regulations pertaining to waste management. Bigger mines have an entire team dedicated to handling environment-related issues such as waste management.

What often happens is that the mines issue tenders for waste treatment or management and then select a compliant and reputable waste management service provider to provide the service. “Most mines do it quite well. By and large, there is an understanding in the mining community that operates this way,” explains Morrey. There are also many derelict mines in South Africa that still have waste stockpiles and contaminated areas that contribute negatively to the environment. The future as to how these wastes will be managed and who will pay for the remediation remains uncertain. Similarly, artisanal mining (zama zama) operations are conducted with little care of any regulations and any waste and environmental legacy related to these operations becomes problematic.

He also notes that understanding waste management in the mining industry is more than just treating or disposing of waste in the right manner. There are three objectives that have become part of a holistic understanding of mine waste management.

The first is community involvement, where relationships between mines, communities and service providers have been forged. The purpose of such relationships is to add value to mining host communities. In addition, these relationships also support and enhance BBBEE requirements as set out in the Mining Charter.

The second objective focuses on waste, whereby mining companies are starting to look at waste as a resource. This ties in closely with the waste hierarchy, which talks

Waste rock can be reused to backfill open voids

WASTE MANAGEMENT

If we look to the near future, we are working towards creating economically viable solutions for mines.”

There are eco-friendly solutions to clean up hydrocarbon waste on mines (Credit: Pratley)

to reducing, recycling and reusing waste. In a paper – entitled ‘Recycling, Reuse and Rehabilitation of Mine Wastes’ – Bernd Lotter outlines possible ways to reuse and recycle mine waste. Waste rocks can be used to backfill open voids, as landscaping material and as asphalt materials. The paper further states that mine waters can be reused for dust suppression, industrial and agricultural use, and to generate electricity using fuel cell technology.

Morrey explains that mines are exploring various technologies to help them minimise and prevent waste generation.

The final objective is zero waste to landfill, whereby mine companies are looking to improve on the percentage of waste produced by their operations. Composting and bioremediation processes are potential options to help mines reduce the waste produced.

Morrey explains that working towards the three objectives will inevitably increase the technology costs of mining companies. The advantage is that the mining industry can be part of and contribute towards the circular economy. Morrey explains that mine companies are taking the initiative towards meeting these objectives, despite potential increases in costs. He adds that a lot of companies are engaging with waste management service providers to find possible solutions that will help reduce their waste. “If we look to the near future, we are working towards creating economically viable solutions for mines,” Morrey says. He adds that waste management companies are always open to support mine companies in meeting their objectives.

Future of mine waste management

Morrey insists that a clear understanding of the waste management services as well as the full requirements of the law is vital. Another important step is for all stakeholders to collaborate with each other in order to ensure full compliance. Collaborating with local host communities in this regard is significant.

“There is a lot of intent and desire by progressive mining companies to progress towards a green economy. In so doing, this will contribute towards a healthy environment and a sustainable mining future,” Morrey concludes.