Abstract.

Light detection and ranging (LiDAR) technology has recently been used to solve many problems in various fields. Quarry mining is no exception. LiDAR scans the quarry and determines essential parameters such as the depth and volume of material mined during the planning stage and throughout the quarry’s life cycle.

This paper examines the use of LiDAR in the mining industry and how LiDAR can help save money by providing the necessary data for job planning.

The sections that​ will be reviewed are “Introduction to LiDAR,” “Mining Management and its Technology,” and “How LiDAR can help in Mining Management.” Finally, the benefits of using LiDAR for job planning will be summarized.

Section 1. Introduction to LiDAR

To begin, it is essential to familiarize yourself with the basic principles of LiDAR. The term LiDAR is short for light detection and ranging. This geospatial technique works by sending focused light beams and determining how long it takes for them to return after reflecting off an object, Figure 1.

When a LiDAR laser beam hits an object like a tree or rock, the light is reflected and returned to the sensor. A LiDAR system can calculate the distance to each point from which the light bounced by measuring the return time of each laser pulse. These calculations are performed using the time-of-flight (ToF) method, which is based on the constant speed of light.

Figure 1. Conditional demonstration of LiDAR operation.

Each resulting point forms a “point cloud” — a three-dimensional display of the scanned area in the form of points. LiDAR models differ mainly in scanning angles (vertical and horizontal channels), number of returns, and accuracy. Most modern LIDARs can operate in several scanning modes. For example, RESEPI XT32 can adjust the rotation speed, scan angle, and number of returns, which will affect the density of the point cloud as well as the ability of the laser to penetrate under trees, grass, etc. [1].

The combination of LiDAR and an inertial navigation system (INS) forms a system that determines the coordinates of each point, resulting in a georeferenced point cloud with centimeter accuracy [2]. An example device that takes advantage of all these advantages is Inertial Labs’ RESEPI payload [3]. RESEPI Payload is a small package fully customizable for any use case. Users can choose a configuration with a camera, a LiDAR model, and a GNSS receiver. The standard configuration is designed for use on drones and other types of sUAS (small, unmanned aircraft systems).

After the flight, the raw data must undergo post-processing—thanks to this procedure, a georeferenced point cloud is formed. For this, companies such as Inertial Labs have developed special software, PCMasterPro [4]. The software does not require preliminary preparation; all operations are performed semi-automatically. Both hardware and software are designed for ease of use.

Section 2. Mining Management and its Technology

The main economic objective of quarrying is to extract the least material and obtain the greatest return on investment by processing minerals. To maximize the benefits of accessing the most valuable material within a mineral deposit, a mine plan is developed that details exactly how the ore will be extracted and processed [5].

Because many deposits do not have a uniform shape, exploratory drilling is carried out to determine the geology and location of mineral strata before drawing up a mining plan. The size of the seam determines the size and position of the quarry. The pits consist of concentric benches or berms bisected by access roads to the mine and by access roads angled from the pit’s edge to the bottom in a spiral or zig-zag pattern, Figure 2. For pits of any size, a mine plan describes the direction of the mining operation: infrastructure (warehouses, offices, technical premises), transport, equipment, production rates, and coefficients. The speed and rate of production influence the life of the mine, which is determined by the depletion of the ore body or the achievement of an economic limit [6].

Figure 2. Copper quarry in Chuquicamata, Chile.

Mining equipment is selected Depending on the quarry’s topography, the surrounding area, and the length of transport routes. The larger the quarry, the more equipment power is required to complete the mining plan. Elevation also plays an essential role in determining the feasibility and scale of a mining project. Generally, the higher the altitude and rougher the terrain, the more difficult mining and mining will be [7].

High-quality minerals may be difficult to mine in inaccessible mountainous terrain, while lower-quality ore is more efficient in low-flat terrain. Thus, topography and location influence the extraction method and economic feasibility. The decision to begin mining is made after exploration has characterized the ore deposit, and a feasibility study has identified options for mining and processing the minerals.

The information needed to develop a quarry plan may include the shape, size, and grade of the orebody and the total volume or weight of the material, including overburden. Other factors include access to a process water source, energy sources, waste rock storage locations, transportation needs, and infrastructure features, including the location of human settlements to support the workforce or the need to build or develop a city [7].

Quarrying typically requires large areas of land that may lack existing infrastructure. In such cases, roads and housing must be built first. Depending on the degree of integration required, the quarry will be developed with other processing elements such as waste rock stockpiles, crushers, concentrators, smelters, and refineries. Due to the large amount of capital required to finance these operations, development may be carried out in stages to exploit the minerals as early as possible for sale or lease to help fund the remainder of the development.

Section 3. How LiDAR can help in Mining Management

Using LiDAR at the stage of drawing up a mining plan is the fastest way to obtain a georeferenced digital map of the area for further planning of infrastructure, housing, and road construction. Using LiDAR will enable a point cloud for already working quarries, making it easy and quick to estimate the volumes of ore mined, evaluate the quarry profile, and calculate the production coefficient [8]. You need a drone, LiDAR, and a base station to scan a quarry. The point cloud contains enough information to plan work – coordinates, time, and intensity. The speed and accuracy of scanning will help reduce costs during the planning phase, as well as during the life cycle of the quarry, that would otherwise be spent on manual measurements.

Using LIDAR with a drone will allow you to scan an area, as shown in Figure 3, quickly.

Figure 3. Inertial Labs RESEPI Payload installed on a drone.

Suggested linear velocity while LiDAR scanning is 5 m/s. For RESEPI XT-32, the recommended flight altitude is 50m to achieve optimal accuracy and coverage (100x28m). Thus, it will take only 20 minutes to scan an area of 0.5 km^2. If you use laser rangefinders or GPS measurements, this can take many hours [9].

LiDAR can scan without lighting, unlike photo cameras, because it has an infrared source; hence, LiDAR can scan at night. RESEPI Payload can also install a camera to obtain colored point clouds. Photographs can also be used for photogrammetry if necessary.

Because the point cloud is three-dimensional, the user can quickly and easily measure the volumes of material mined, estimate the depth of the quarry, and plan future operations as mining progresses. Third-party software (LiDAR360, TerraScan, etc.) implements the ability to assess volume and extensive capabilities for conventional measurements such as area, length, and much more [10, 11].

With remote scanning, safe mining increases because a person does not need to get close to the rock to measure its orientation or volume; thus, no one will be harmed in the event of a collapse [12]. For example, in 2023, a massive collapse occurred in a coal mine in Mongolia, leaving 57 people missing [13].

Like any other technology, LiDAR also has disadvantages. As with drone photogrammetry, weather conditions can significantly affect the data recording process. For example, scanning in rain or high winds is impossible when the drone may lose control. When scanning at night, the user cannot obtain a colored point cloud.

To start using the RESEPI payload, the user will need a drone, flight license, RESEPI payload, base station, and a PCMasterPro software license for data processing [14].

Conclusion.

Drawing up a mining plan is a critical procedure that determines how and under what conditions mining will occur. Competent and effective planning is the key to successful work throughout the entire life cycle of production.

Therefore, obtaining high-quality and accurate site information is critical to planning the quarry infrastructure and, as mining progresses, reporting and evaluating mining productivity. Manual measurements are time-consuming and expensive and can also risk people’s lives and health. Using LiDAR for aerial scanning with a drone will provide high-precision data for quarry planning, estimate the volume of materials mined, and measure the depth and width of the quarry for further refinements and infrastructure development.

Although weather conditions limit camera-integrated LiDAR payloads such as Inertial Labs’ RESEPI Payload, they allow the user to obtain highly accurate geo-referenced color point clouds. They can also operate at any time of day. Another advantage is the ability to use camera images for photogrammetry if necessary. Thanks to third-party software, the user can use the collected information to measure quarry parameters at the planning stage and during mining.

LiDAR capabilities make mine planning easier and faster, making it safer and more efficient.

References.

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[5] Wikipedia Contributors. “Mining Engineering.” Wikipedia, Wikimedia Foundation, 21 Sept. 2019, en.wikipedia.org/wiki/Mining_engineering.

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[9] MacIntyre, John. “A Guide to Topographical Surveys.” Technics Group, 2 Apr. 2024, www.technicsgroup.com/2024/04/everything-you-need-to-know-about-topographic-surveys/.

[10] “LiDAR360 Software and Real-Time Point Cloud Display.” www.greenvalleyintl.com, www.greenvalleyintl.com/LiDAR360/.

[11] “Tersolid – Software for Point Cloud and Image Processing.” Terrasolid, 21 Sept. 2023, terrasolid.com/.

[12] Alejano, Leandro R, et al. Slope Geometry Design as a Means for Controlling Rockfalls in Quarries. Vol. 44, no. 6, 1 Sept. 2007, pp. 903–921, https://doi.org/10.1016/j.ijrmms.2007.02.001. Accessed 13 July 2023.

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[14] “Buy Reach RS2+ | Buy Multi-Band RTK GNSS Receiver.” Emlid Store US, store.emlid.com/products/reach-rs2-plus?variant=47253689467185. Accessed 3 June 2024.