This article was presented by Python Mining Consultants
Electric Mining Equipment
Transportation systems seem to be on the verge of a massive make-over. This has largely been triggered by two things. Firstly, it appears that inexpensive oil reserves around the world are depleting rapidly and will not be able to satisfy the global demand much longer. Furthermore, the environmental issues that occur as a result of burning fossil fuels have also made burning gasoline or diesel products an undesirable action. This is regardless of whether or not there is enough cheap crude to go around. As a result, several alternative technologies have been researched and developed in an attempt to replace the internal combustion engine (ICE). Of these technologies, it would seem that electrically powered vehicles are the most likely candidate to replace ICE powered vehicles. This is evidenced in the automotive industry. Not only are hybrid (powered by an ICE and an electric motor) vehicles commonly found on the road today, but fully powered electric cars appear to be around the corner. General Motors has began selling the Volt while other automakers are right behind (for example: Nissan is about to launch the Leaf). Similarly, the mining industry has begun implementing some electrically powered machines into their fleet of equipment. That being said, the transition from oil powered vehicles to electrically powered vehicles has been slow in the mining industry and many mining companies are still operating mines with fully powered diesel fleets of equipment. The following article will outline some of the advantages and disadvantages of operating electrically powered equipment. This article will also attempt to look at some of the individual pieces of electric equipment that have been used successfully in mines.
There are several advantages to using electric equipment versus diesel powered equipment in mining operations. The most significant of these benefits is that electric machines typically have lower operating costs. This is as a result of several things. Firstly, electricity is much cheaper than diesel in most parts of the world. This spread will only further benefit electric vehicles in North America as fuel prices are expected to continue to increase substantially in the coming years. This is also in part due to the increased efficiency of electric motors. While the most advanced and highly engineered diesel engines have efficiencies between 25% and 45%, the world’s most advanced electric motors can achieve efficiencies as great as 90%. This results in lower overall watts of energy required (from the fuel) to power the vehicle. Finally, the lower operating costs are also due to the fact that electric vehicles require less maintenance. Electric motors, and many of the parts that are required to power electric machines, have very few (if any) moving parts. This results in less wear-and-tear and typically results in a more reliable vehicle. Furthermore, electric motors provide impressive low-end torque. This makes them ideal for many mining vehicles which require high levels of torque and typically travel at low to medium speeds. In addition to that, electric vehicles are very quiet, produce much less heat that diesel machines and do not produce any exhaust. Not only does this result in a much more pleasant working environment but it is particularly important in underground operations which invest a great deal of energy and money to properly ventilate underground workings. Furthermore, electric machines also result in a much smaller carbon footprint, which has become an increasingly important feature in recent years. As with any technology, electric vehicles also have several disadvantages. The following section outlines a few of the electric vehicles that are being used in mines today. Their respective disadvantages are listed within.
Electric Haul Trucks
Electric Haul trucks have been adopted into many mining operations. These trucks provide powerful alternatives which offer the advantages already listed when compared to conventional diesel haul trucks. They are also capable of travelling at much faster speeds while going up steep grades. Unfortunately, these trucks require a higher capital investment. This is in part due to the cost of the truck, but also due to the fact that they are powered by an overhead trolley system. This trolley line must be installed the length of the haul road in order for the trucks to operate. Unfortunately, electric haul trucks remain a “necessity” item in which many mining companies opt to go with electric trucks only when diesel trucks are not suitable. This is usually the case for deep mines. These mines become increasingly difficult to ventilate which makes the exhaust free electric trucks the best choice. It would seem that most mine management people are more concerned with capital costs than operating costs, lifetime ownership costs or costs/tonne which are all better with electric trucks.
Electric shovels have been implemented with a great deal of success in open-pit mining. These shovels also provide great power and the lowest costs per ton (operating). P & H Mining Equipment Inc. is an example of a manufacturer that has developed a popular line of electric shovels. They offer models that very in bucket size from 21 tons to 155 tons.
Electric Scoops have been implemented in some quantities in underground mining operations. These scoops are fitted with a trailing cable and a reel behind the vehicle that allows the vehicle to be plugged into a power source. Unfortunately, this system has yielded less manoeuvrability as operators must attempt not to run over the cable. Atlas Copco manufactures electric scoops. They offer a line of electric scoops with bucket capacities that range between 3.6 and 6 tons. The scoops are also equipped with a random wrap wheel cable which offers automatic cable tensioning to reduce the inconveniences of having a trailing cable.
Electric Vehicles in Mining
As a result of lower operating costs, lower environmental footprints and rising oil prices, it would appear that electric machines will play an increasingly larger role in mining operations in the future. Research efforts are on-going to improve the machines mentioned above and make them more suitable for mining operations. Mining personnel should at least consider this fact when outlining future designs. This will allow them to incorporate electrically powered machines into their operations easily. Furthermore, hybrid haul trucks and hybrid scoops are beginning to hit the market. These units offer companies a fuel saving option which does not require the capital construction of a trolley line or the use of trailing cables with scoops. Finally, man carriers and personnel transport jeeps and trucks will likely begin to be swapped-out with hybrid or electric variations. The low speeds that many of these vehicles operate at makes them ideal for electric vehicles, which achieve their greatest ranges at low speeds.