In mining operations, accurate stockpile volume measurement is not merely a matter of convenience; it's a critical element that can significantly impact productivity, safety, and profitability. Traditionally, this task has been carried out using manual methods that involve time-consuming processes, including ground surveys and physical measurements. Not only do these methods demand substantial labor, but they are also prone to human error. Furthermore, safety is paramount at mines, and the traditional approach poses risks to personnel.
At EnviroMINE, we’ve utilized the power of drone technology, since 2014, to create a stockpile measurement process that sets new standards for precision, efficiency, and safety. In that time, drones have become a standard practice in the industry and have been widely accepted as the tool of choice for most companies. However, not all drones and their platforms are created equal and the technology itself does not guarantee an increased level of accuracy. There is still a need for a competent methodology and understanding of the complications facing drone-based stockpile measurements.
Most drone platforms offer a similar end-product for their customers. As required by federal law, drone pilots must be licensed to fly at a mine. Images from the flight are processed into a two-dimensional map (see below). For the DIY variety, the customer can then outline the stockpiles on the map and get the results of the measurements relatively quickly. This process can offer a fast and simplistic approach, but not all mines and stockpiles are suitable. Below we will see how there are situations where a different methodology is necessary.
Figure 1 – Typical 2D map on most platforms.
Example 1: Adjacent Stockpiles
At most mines, space is limited for stockpiled material and many operators end up stacking piles near or up against each other. This can create a challenge when trying to measure a stockpile on a two-dimensional map. As you can see in the example below, outlining the two stockpiles appears to give us a perfectly good measurement of them.
Figure 2 – 2D view of two adjacent stockpiles.
When we look at that same measurement in a three-dimensional map, we can see that the outline of the stockpile is following the elevation of the pile (over the top of where the two piles meet) and the measurement is not capturing the full volume of both piles.
Figure 3 – 3D view of inaccurate base points.
Our solution? Using our three-dimensional approach, we can measure both piles below the ground surface and confirm that we are capturing the entirety of both piles.
Figure 4 – 3D view of accurate base points.
Example 2: Abnormally Placed Stockpiles
At many of sites we fly, most of the stockpiles are placed against a slope at the site. The piles are often too large to determine where the slope ends and the piles begin when looking at the two-dimensional map. These stockpiles might go back as far as fifty feet past the edge of the slope in some instances.
Figure 5 – 2D view of abnormal stockpiles.
Figure 6 – 3D view of abnormal stockpiles with inaccurate base points.
To circumvent this issue, we had a surveyor measure the placement of the base points of the stockpiles and calculate the elevation based on the historic topography of the site. Using these base points, we can accurately adjust the bottom of the piles so that our measurement captures the full volume.
Figure 7 – 2D view of stockpiles with surveyed base points at toe of slope.
Figure 8 – View of the stockpiles below the surface shows how the surveyed base points capture the stockpiles material going back to the original placement of material (red is measured stockpile).
Example 3: Historic Stockpiles
Some mines require an even more unique approach. At the mine below, a few of the stockpiles have been continuously expanding for over a decade. The challenge arises from the prolonged accumulation, which has obscured the original terrain, making traditional methods of base point placement at the surface impractical. Instead of relying solely on the new topography we capture with our drone, our methodology involves comparing it with an older topography.
Figure 9 – Existing Topography of Current Stockpile.
Figure 10 – Historic Topography of the location where the stockpile would be placed. The stockpile was placed against a slope making it difficult to determine the true base without historic topography.
Figure 11 – Cross Section of the existing and historic topography.
While the concept of utilizing historical data for improved accuracy isn’t entirely novel in the stockpile measurement industry, surprisingly few drone services have integrated this approach on their platforms. Most use an automated system to measure the stockpiles after they are circled on the map by the customer and don’t consider the need for further analysis.
Conclusion
In revolutionizing drone-based stockpile volume measurements, EnviroMINE's commitment to a three-dimensional methodology stands out, tackling challenges that traditional two-dimensional mapping often overlooks. From improving the accuracy of measuring adjacent stockpiles to handling abnormally placed ones against slopes and addressing historic accumulations, our precision extends beyond automated systems. Each stockpile undergoes meticulous review, setting us apart in an industry where technological advancements must be complemented by expertise. In a world where accuracy is key, our commitment to innovative methodologies positions EnviroMINE as a leader in drone-based stockpile measurements.