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Preparing the mining industry for a changing climate

How much carbon dioxide does the mining industry produce each year? How will climate change impact mining operations at a physical level? And, are we doing enough to halt it? asks Carly.

I had a lot of questions about mining and climate change when I first began researching this feature. If I’m honest, one of the main reasons I chose to cover the topic was to quench my own thirst for knowledge.

There are two aspects to consider when talking about climate change and the mining industry. Firstly, climate change mitigation: reducing greenhouse gas (GHG) emissions in order to minimise our contribution to global temperature rises. And, secondly, preparation for the changes that a warming climate will bring. For example, water scarcity (or excess), loss of biodiversity and a reduction in available land.

In 2014, the Intergovernmental Panel on Climate Change (IPCC) published its AR5 Mitigation of Climate Change report. The publication is updated every seven years and the next iteration is due in 2021, so although AR5 feels a little out of date, it is still one of the most comprehensive sources of data available on the subject.

According to Chapter 10 of the report, global industrial CO2 emissions totalled 13.14 GtCO2 in 2010. These comprised 5.27 Gt of direct energy-related CO2 emissions, 5.25 GtCO2 indirect emissions from electricity and heat production, 2.59 GtCO2 from process emissions and 0.03 GtCO2 from waste/wastewater.

The production of ferrous and non-ferrous metals accounted for 2,127Mt of direct CO2 emissions (see table below) as well as some process emissions related to refining and smelting.

While the mining industry was not the biggest industrial contributor of GHGs globally in 2010, it is safe to assume that these figures have risen significantly over the past decade. And demand for metals is predicted to grow sharply over the next 30 years thanks to urbanisation and their requirement in green technologies, like battery electric vehicles and wind turbines.

Table of 2010 direct and in-direct industrial GHG emissions by source and gas. Taken from IPCC AR5 report, 2015
Direct and in-direct industrial GHG emissions in 2010 by source and gas. Source: IPCC, 2015

The amount of ore needed to produce one tonne of metal has also increased during this time thanks to depleting ore grades. Morgan Stanley states that the amount of ore required to produce one tonne of copper has risen by 17% since 2014, meaning that greater amounts of energy, chemicals and labour are required to produce each tonne of metal.

According to the IPCC, in 2010, energy consumption for mining and quarrying represented around 2.7% of total worldwide industrial energy use, and a significant share of national industrial energy use in Botswana and Namibia (around 80%), Chile (over 50%), Canada (30%), Zimbabwe (18.6%), Mongolia (16.5%), and South Africa (almost 15%).

These numbers are colossal and, if left unchecked, they will rise steeply, endangering the profitability and sustainability of our industry.

Investor interest accelerates action

According to the International Council on Mining and Metals (ICMM), approximately half of mining and metals industry emissions are classed as scope 1; from use of diesel fuel in mining and processing operations and from fugitive methane (CH4) emissions at coal mines. The other half are scope 2, from use of electricity, primarily in refining and smelting.

Mining companies must address both if they are to maintain their social license to operate and, over the past 12 months, several big players have announced plans to de-carbonise their operations, some even committing to reductions in scope 3 emissions as well.

A big factor in this is increased pressure from stakeholders. It’s no secret that investors are looking more closely at the business practices of the firms they back and leaning heavily on them to improve the sustainability of their processes; people care where their money is going.

It is this heightened support that has emboldened many technology suppliers to launch their own programmes to tackle climate change.

In late 2019 when I began researching this piece, FLSmidth announced an initiative called MissionZero. This will develop solutions that enable customers in the mining and cement industries to operate zero emissions processes by 2030.

Manfred Schaffer, president of FLSmidth’s mining division, talked me through some of the key aspects of the programme. He said that, from a business perspective and, also at a viability level, heightened interest in sustainability was an important factor in the timing of the launch.

“It’s clear that investors are concerned; they do not want to invest money in an industry that is, from an environmental point of view, damaging,” he explained.

“The pressure will not go away, as climate change will not go away; this issue will only accelerate. All miners need to plan how they will handle the use of energy, water, and minimise their footprints.

“We believe that a big part of the solution will come from technology, and there we can help.”

Conserving water supplies

The company has spent much time investigating areas of the mining process that could be improved and potential technologies it could offer.

When it comes to reducing GHG emissions, Schaffer cites in-pit crushing and conveying as a feasible alternative to truck-shovel operations, pointing to Vale’s S11D operation in Brazil as an indicator in the scale of system capability.

Less energy-intensive comminution technologies are another option, including some such as high-pressure grinding rolls (HPGRs) that originated outside of the mining industry. These have also proven their worth at large-scale operations.

An aerial view of in pit crushing and conveying operations at Vale's S11D mine
An aerial view of in pit crushing and conveying operations at Vale’s S11D. The mine is fully truckless. Image: Vale

But, as mentioned earlier, climate change mitigation is just one piece of the puzzle; miners must also prepare to deal with the impacts of climate change, and one of the biggest and most expensive challenges they face in this regard is water.

In water-scarce regions, the sourcing and replacement of water used in mineral processing can cost tier one miners hundreds of millions of dollars a year.

Water is currently utilised as a carrier within mineral processing circuits. In milling and grinding, its primary role is to transport particles of rock from one stage to the next. However, the main requirement is in beneficiation which, for most commodities, relies heavily upon flotation.

For the uninitiated: in flotation, fine particles of rock are mixed in a tank with large volumes of water plus reagents, and then air is introduced to create a froth. The chemicals used can be tailored to ‘float’ or ‘depress’, basically separate, certain minerals.

It’s an old process but a highly effective one which has been a mainstay of mineral processing for over 100 years. And, until alternative technologies are found that can yield the same recoveries at a competitive price, it is likely that flotation will remain king.

Waterless processing by 2050

Most water is lost through evaporation and seepage from tailings (mine waste) after deposition in a dam, so developing dewatering and dry storage methods are currently a big focus for mineral processing firms, including FLSmidth.

But what if it were possible to remove water from mineral processing altogether?

“We have been working on this for a few years now,” Schaffer told me. “We have a two-step approach: first to find a solution to dewater and dry stack tailings on a large scale, so that we have 100% recyclable water. That is our vision up to 2030.

“In parallel, we are working on solutions that allow dry processing, using no water in mineral separation. That’s our aim for 2050.”

Leaching technologies used, for example, at in-situ operations, and solvent extraction currently offer the greatest potential in this regard.

It is flotation and the very fine particles this requires that currently dictates the need for highly energy-intensive, ultra-fine grinding technologies within processing flowsheets. So, use of alternative beneficiation technologies could also help to drive down CO2 emissions too.

Less land? Head underground

Loss of land is another aspect to consider.

It is becoming ever harder to obtain environmental permits for greenfield operations and, with the need for greater throughputs comes the need for larger concentrators.

“Once we have 100% dry tailings, this will help us to reduce mine footprints,” Schaffer said, acknowledging that wet tailings storage facilities require huge amounts of space. “We’re also looking at new concepts where mineral processing plants could be made semi mobile or taken completely underground. From the surface, you wouldn’t even see the mine.

“Of course, this concept has limitations because of the size of certain technologies. But, at many underground mines, it would make sense to process the ore underground, and not bring it to the surface, process it, then send the waste back.”

Water droplet. Image: Pixabay
Responsible water management is one of the biggest and most expensive challenges that miners face thanks to climate change. Image: Pixabay

Schaffer said he isn’t aware of any mines that are currently doing this on a large scale. However, as a first step, many underground operations are introducing mineral sorting technologies underground to ensure that only high-grade material is brought to the surface for processing.

The next step would be to introduce a small-scale processing plant (or multiple plants) that can be operated underground, and there are one or two examples of these already on the market, for example, Gekko’s Python.

“It would help, not only from an environmental perspective, but the potential capital and operational savings could also be huge,” Schaffer added.

Open to change

Schaffer said that FLSmidth is seeing a lot of interest in new concepts, particularly in the elimination of wet tailings facilities; he hopes that dry stacking will be an industry standard by 2030.

“It’s an exciting time for suppliers like FLSmidth,” he told me. “Because we really believe now that mining companies will look at these new technologies. It gives us opportunities to develop solutions together and differentiate ourselves by having smarter ideas.

“In the past, mining innovation was just about making things bigger and faster. But now we have environmental and productivity challenges that will require that the industry to be more open to new concepts and flowsheets.

“I think close cooperation between the suppliers and the operators is necessary to make this work in the ambitious timeframe that we all have.

“We just need to find the right partnerships.”

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