During my placement at Banks Mining I have seen how the company is constantly innovating, improving and diversifying to become more efficient, safer and to carry out work to a higher standard. Banks seek to operate to a high degree of efficiency, and accounts for all greenhouse gases and looks for opportunities where improvements can be made, using intelligent solutions to reducing its greenhouse gas emissions. Banks Mining is proud of its safety record and is never complacent and is looking for continuous improvement in all areas and therefore new measures are being used to improve our performance. I’ve been spending some time with our mining team to see how coal and fireclay go from being underground, to being mined, then into stockpiles for processing at Shotton before finally being delivered to our customers by Banks Transport fleet (see: https://www.banksgroup.co.uk/2019/11/19/blog-no-10-delivering-with-care-placement-student-harry-mccabe-spends-a-day-with-banks-transport/). It was good to see the full process of coal mining occurring in person.
In January 2018, the engineers at Banks Mining began using a drone to help with mining operations. Using the drone, our engineers can accurately, efficiently and safely survey volumes and map changes as our mining sites progress. I spent time with one of our drone pilots and engineers Peter Faraday, to become more familiar with how we are improving operations by using drones.
The need for the technology
For a bit of background, geographic data is an essential requirement in mine engineering. The key role of our engineers is to produce topographic surveys of our surface coal mines. Topographical surveys are utilised throughout the entire life of a surface mine, from planning, where noise prediction modelling scenarios and plant requirements are identified, to restoration and aftercare plans are designed and implemented. In surface mining, sites change quickly, particularly as we mine coal in different areas of the site and carry out progressive restoration. Working voids and the location of haul roads shift around the site, soil mounds are constructed and de-constructed and overburden is excavated and deposited in above ground stores or progressively backfilled in the area of the void where all the coal and fireclay has been extracted.
Banks Mining engineers use computer software to create accurate, 3D models of our mining sites at different stages during the project. These models are integral to the roles of site managers, planners, coal pad supervisors and the coal sales department, landscape architects and plant operators who need to have an accurate representation of how the site should be worked, how the site will be progressively restored and the volumes of coal and fireclay being extracted.
In the past, the engineers have used traditional surveying methods which over the years evolved from theodolites to global positioning systems (GPS), to create the site models and map the changes that occur. GPS surveying involves using a GPS measuring pole, with a small satellite receiver that pinpoints the geographic location of the user on-site (like a big “dot to dot”). The location of the user is recorded. After a few locations are recorded, the points are connected, creating a computerised net (called a surface model) of accurate locations within our site. This, along with the geological data for the site allows the engineers to create engineering plans of areas to be worked, calculate the amount of material to be moved by our plant fleet and map the changes occurring on-site as operations progress. Traditionally the engineering team would have to survey potentially hazardous areas working near heavy plant equipment, walking around the site carrying survey equipment and taking measurements to update the survey plans. Surveying can be costly and time consuming depending on how much the mine has changed since the previous survey was undertaken. The surveys also impact production as machines have to stop to enable the engineers to safely carry out their work. The traditional methods provide good results but the company are always looking to enhance safety performance and advance efficiency with new initiatives. The work done by the engineers is invaluable to our mining operations, so developing a new method of surveying had to meet the same requirements as traditional methods. Any new survey method had to be sustainable and provided a lasting solution.
Using the drone
Creating maps and projections of reality by using a drone is called aerial photogrammetry. Photogrammetry is the science of making a measurement from a photograph. In the past this required an aircraft with a specialised stereoscopic camera which was both expensive and weather dependant. A drone, in very simple terms is a flying camera which can be deployed very quickly at a much lower cost.
Our sites in Northumberland are fairly close to Newcastle airport, so before flying the drone, Newcastle Airport is notified that we will be flying. The pilot and the ‘spotter’ will drive to the part of the site they would like to survey, for example, at our Shotton site, the pilot may take one of our site vehicles to the main void restoration area, set up the landing pad for the drone, ensure it is safe to take off and begin the flight. The drone will take off, up to 6m/s vertically, and begin to scan a pre-defined flight path. The path the drone takes is called the waypoint. During the flight, the drone will take hundreds of high-quality images. Depending on the required survey output, the drone can be used for stockpile volume measurement, terrain mapping and site planning. A drone flight to survey a specific area of the site takes around 10-20 minutes, in which time, both the pilot and the spotter will need to look for low flying aircraft in the area. Should any aircraft approach the site whilst the drone is flying, then the drone pilot will immediately land the drone to avoid any potential risk to the aircraft.
Our engineers use a DJI Phantom Four Pro. This is a state-of-the-art drone weighing just 1.4kg; a bit different to 150 tonne trucks and 590 tonnes excavators working below it! The drone can travel at up to 45mph and has a maximum flying height of 6,000m, however, we only fly the drone to a height of 120m (approx. 400ft) in height and 500m in distance from the pilot. The drone is fitted with a 25mm, 20-million-pixel, 4k camera used for capturing images of the site. The drone is also fitted with dual navigation and collision avoidance systems- both key safety features. Millions of data points and hundreds of images can be taken over the area of our sites using the drone. To be able to fly our drone, our drone pilots were trained by the Drone Pilot Academy, which is Civil Aviation Authority approved, and received an NVQ in drone piloting.
The clever bit
The drone is basically a tool used in photogrammetry in which the fundamental principle is triangulation. By taking photographs from at least two different locations, “lines of sight” can be developed from each camera to points on the object being viewed. These lines of sight are mathematically intersected to produce the three-dimensional coordinates of the points of interest. (Triangulation is also the principle used when surveying with traditional survey methods to produce 3D coordinate measurements) but is also the way our two eyes work together to gauge distance (called depth perception).
The images taken by the drone with coordinates on are then stitched together by some clever computer software, Pix4D mapper, to create an extremely accurate 3D model of the site. The 3D model is a dataset in the form of a digital elevation model (DEM) or digital terrain model (DTM), which are both electronic surfaces, made up of a web of points, that can be used for mapping our sites. The accuracy of the coordinates produced is determined using ground control points- which have the exact known co-ordinates attached to them. Ground control points are established by accurately surveying a pinpointed location which can be readily identified on the aerial photographs. Our engineers use purpose made targets with a large white cross which can be easily identified on the photographs. The ground control points allow the photographs to be georeferenced, meaning they are validated by being compared to the correct location of a point. The model produced by the software is accurately attached to a web of known ground control points. These surface representations can be used in volume calculations, structural geology and slope analysis.
The result from photogrammetry is always a map, model, image or calculation. Most maps used today are created from photogrammetry. Photogrammetry can be commonly mistaken for Light Detection and Ranging (LiDAR), a very similar technology. LiDAR uses laser scanning techniques to detect position and shapes of object whereas photogrammetry uses the images to make measurements and create surface models of an area.
Why use the drone?
Whilst the use of drones, or unmanned aerial vehicles (UAVs), is an emerging technology, it has all types of applications. We are using UAVs to map our mining sites, but drones have been used for the construction industry, urban planning, archaeology and land use change mapping such as sea ice coverage and forest and woodland reduction mapping. The ease and efficiency of the technology, as well as the wide scope of applications means it is being implemented globally by engineers, planners, environmental scientists and geologists.
Banks are absolutely committed to implementing solutions to increase efficiency and health and safety performance. In the past we have created technology and implemented strategies to increase the safety and efficiency of our operations. Using the drone, we are able to reduce the need for our engineers to enter potentially hazardous environments where heavy mobile plant is operating such as our coal processing area. We are also able to survey areas such as restoration, working voids, overburden and soil mounds much faster by using the drone, without compromising on accuracy. The use of the drone means our engineers are safer whilst still being able to produce highly accurate computerised representations of our mining sites!
The drone technology is a great example of Banks actively improving operations, leading to enhanced performance. I really enjoyed going out on-site with Peter to learn about drone technology. I’ve previously done some photogrammetry and remote sensing modules at university, which I found tough, so to attach a practical aspect onto my basic understanding was both interesting and useful for me, allowing the learning concepts to become clearer. I was sceptical and almost doubtful of this technology when learning the theory but seeing it in practice I was really impressed. The drone flying is another opportunity I’m really pleased to have been offered during my placement here and I hope to be out on-site with Peter again very soon!