Diesel engines have long been the industry convention for mining, despite they are inefficient at transforming fuel energy into work. Diesel engines for mining have about 45 per cent efficiency. On the other hand, electric drivetrains can have an energy efficiency of around 90 per cent. The cover story takes a look at what is the future ahead of us on sustainable mining.
Mine exploration, operation and maintenance majorly results in change of land use. It is often associated with negative impacts on environments, including deforestation, erosion, contamination and alteration of soil profiles, local streams and wetlands.
Increase in noise level, dust, pollutants, etc. are very common. A major damage is received by the locals around the mine. On this background let us look at some sustainability aspects of mining.
Sustainable mining is a buzzword today. A step in the direction of sustainability, the electrification of mining vehicles will likely to gain momentum as mines age, technology advances and mining operations extract ore deeper and deeper into the Earth.* According to a projection by IDTechEx, electric mining vehicles mining will be a $9 billion market by 2028, with businesses like Sandvik, Komatsu, and Caterpillar currently working on completely electric equipment.
Why go electric?
There are very solid reasons why the diesel engine has been the dominant drivetrain technology in the mining industry for so long. The working conditions for these vehicles can be very difficult, and the diesel engine is able to tolerate many challenges, including extreme temperatures, heavy vibration, frequent start/stop cycles, exposure to corrosive substances and harsh working conditions. When it comes to emissions alone, reducing the usage of diesel fuel can have considerable cost benefits for the industry, as much as 40 per cent of an underground mine’s energy expenditure is invested in massive ventilation systems. For us in the cement industry, it is an open cast mine but for coal it can be underground mine. However, the initial cost of purchasing an electric vehicle would be about double that of a conventional diesel vehicle. Although this is compensated by reduced long-term fuel and energy costs, the primary costs might be restrictive.
Manufacturers are however taking steps to mitigate up-front investment costs. In an effort to increase sales, mining equipment maker Epiroc announced it would lease batteries for its electric vehicles, making the up-front investment only somewhat greater than it would be for a conventional machine.
As times change in face of countries and industries making ambitious commitments to phase out use of diesel and petrol-fueled motor vehicles. Is it the case that these commitments are now extending to the industries that need it the most? The electrification of mining vehicles has an interesting role to play as mines age and operations continue to extract lower ore grades at deeper levels, a recent mine project feasibility featured in the report outlines reductions in capital and operational expenditure costs due to a reduction in ventilation/cooling requirements of these machines up to 20 per cent and 25 per cent respectively. As the mining industry continues, this focus on increased productivity, efficiency and improved safety, feasibility figures such as these can go some way to justify the profitability of a project.
Price factor
The spread of electric mining equipment will depend not just on the vehicles, but also associated technologies. For instance, advancements in battery technology can lead to a decrease in the price of battery packs for electric mining vehicles. Regenerative energy to power the world’s biggest electric vehicle.
Commonly used in mining operations, a standard dumper truck uses between 50,000 and 100,000 liters of diesel each year, based on its usage. It also typically emits between 130 and 270 tonnes of carbon dioxide. A few steps have been initiated to develop a storage battery pack of 700 KWh for Komatsu truck, world’s largest electric vehicle which are at an advance stage.
The drive controls the flow of energy and transforms kinetic or potential energy into electric energy. Regenerative drives developed for mining vehicles are leading to superior overall efficiency through savings in energy usage and ventilation systems. Dumper trucks are particularly well-suited to regenerative drive systems due to their heavy usage on hills and in mine shafts. While a diesel dumper truck may burn fuel while going down a mine, electric vehicles could actually gain energy on their way down. The Swiss Federal Laboratories for Materials Science and Technology (EMPA) said the converted Komatsu truck may be capable of gaining 40 kWh of its way downhill, something the standard mining truck does 20 times each day. This means 800 kWh of energy capacity could be gained through a regenerative drive.
Electric mining truck
Indeed investing in innovation through technology costs upfront and takes time. In the case of mining this is essential in establishing longevity in productivity gains.
Leading equipment manufacturers-Komatsu, Caterpillar and Hitachi-have had notable success in the role out of autonomous haulage systems, with economic and safety benefits identified as primary drivers and noted increase in productivity up to 30 per cent in some operations.
The proliferation of electric mining equipment whether loaders or trucks will depend not only on the vehicles themselves but enabling and associated technologies. Advancements in Li-ion battery technology in terms of electric range, energy and power capacity will continue to lead a reduction in the cost of battery packs used in electric mining vehicles making the technology more viable.
The battery driven trucks are robust machines built for demanding underground applications. The trucks have been constructed with zero emissions in mind and battery power which leads to lower operational costs. Energy regeneration and the efficient drivetrain configuration will ensure low energy consumption and extend driving range. With the electric drive, battery mine trucks will outperform diesel equivalents, especially on grade.
Electric mining trucks are optimised for productivity in many ways. The drivetrain has been optimised to reduce losses and reduce the number of components. One high power electrical motor is connected to each axel. The electrical drivetrain provides unheard of speed on grades, both up and down the ramp. Hydraulic functions are powered from a separate auxiliary motor that delivers hydraulic power on-demand. Extended battery autonomy is achieved through energy regeneration and high energy density battery design.
Working environment
This zero-emission machine helps to create a healthier work environment and reduces the carbon foot print. In case of open cast mines pollution is not a major problem except dust. But in case of underground mines considerable cost is incurred on ventilation that can be reduced to a large extent by using electric vehicles. High capacity and productivity, thanks to the highly efficient drive train, battery driven trucks hauls material faster than its diesel-driven counterparts.
Maintenance
Safety, productivity and operator comfort is important. But so is service and maintenance to keep the truck up and running. Intrinsically electric trucks require less maintenance and with various smart service areas make daily inspections very easy. Countries, industries and individual companies have all been taking serious steps toward the phasing out of conventional diesel and petrol-fuelled vehicles, and these changes are now being seen in the mining industry.
Contract mining
Contract mining is not uncommon in India. More specifically it is seen in coal mining. In the past for gold mining, we understand there was a contractual firm involved. However, cement industry is not very conversant with contract mining. But there are cases where the transportation of lime stone is given on contract basis. Maintenance of vehicles is given to a few firms. Removal of over burden is often handled by a contractor. These are primarily non-core activities. The core mining activity remains with the plant/ owner. The scene outside our country is different like mines operated in South Africa or Australia where mining industry contributes significantly to the exchequer. The operation of mines that includes core mining activity is handled by a professional contractor. There is a myth that contract mining means labour broking.
What is it?
Generally contractors are appointed for core and non-core services based on bids and tenders. These bids are won on the strength of the proposals and the reputation of these bidders, which is a standard procurement procedure. Contract mining provides mine owners with some of the following advantages according to industry opinion:
Economies of scale and scope through access to capital equipment and human resources
Optimised mining, plant, and equipment utilisation rates and labour productivity
Minimisation of the owner’s capital exposure, which allows the company to better utilise capital
Better equip (or re-equip) mines with restricted capital budget
However there is a flipside also, e.g. more than often safety might be compromised while extracting minerals. The interest of the locals is at stake which may take a back seat. The commercial terms of the contract may overtake the overall sustainability. The legislation that enforces laws often has to be very strong, if we as a country are serious to introduce contract mining in limestone or in other minerals.
*More information on the report can be obtained by visiting to: https://www.idtechex.com/en/research-report/electric-vehicles-and-autonomous-vehicles-in-mining-2018-2028/597
