Application of satellite remote sensing in mining industry



Satellite remote sensing is increasingly being used in a number of industries, including mining. It has been implemented to map and plan mines and help inform safety protocols and automated efforts to create more connected sustainable mining operations. It is also used to provide data that is indispensable for the exploitation of dwindling resources.

Due to the extensive monitoring coverage and the opportunity to accurately define surface features that indicate mineral deposits and track mining-related landscape changes, satellite Earth observation is becoming increasingly popular in the industry.

The types of remote sensors used in the mining industry include satellites, drones, aircraft, and land-based variants. Satellite systems used for mining include Landsat-7 and 8, ASTER and Sentinel-2. Satellite remote sensing systems vary in resolution and cover geographical areas ranging from less than one metre to several hundred metres. Prior to its retirement in 2016, Hyperion's hyperspectral sensor equipment provided critical data for monitoring mining operations.

Other satellite-based systems will be rolled out over the next few years, including EnMAP (Environmental Mapping and Analysis Program). The types of remote sensors used in satellite, airborne and ground systems include thermal infrared thermal imagers and spectral sensors. The onboard systems can be installed on unmanned or manned aircraft. Ground sensors can be hand-held, machine-mounted or fixed.

Remote sensing is a key technology in the transition of the mining industry to a green future. The technology has been at the heart of efforts to curb carbon emissions and reduce pollution levels, and remote sensing has now been used to map the physical impact of mines on their surroundings.

01

What is the application of remote sensing in the mining industry?

Remote observations of the Earth's surface by satellite are applicable to all phases of the mine life cycle.

Satellite imagery is an important means to support mineral exploration projects. They have a very wide range of applications. Can provide geologists and site workers with information about the presence of roads, dirt roads, fences, etc. In other words, satellite imagery is the basis for making land cover maps. This is essential for mapping potential pathways to explore areas and considering the environmental impact of major projects.

Remote satellite-based monitoring simplifies and speeds up geological exploration in hard-to-reach places. In Europe, for example, high-quality mines are almost exhausted, leaving experts to search for new deposits in remote areas.

Satellite maps can also be used to detect outcrops and weathered rock formations and to monitor vegetation in exploration areas.

Monitoring open pits (located on the ground) during extraction is another use case for satellite data. For example, we analyzed Sentinel 1 radar images to track monthly changes in slope stability and the landscape portion of active mining (i.e., to determine the size of the inventory). The purpose of this monitoring is to ensure the safety of workers by detecting potential problems in a timely manner and reporting them to mine management so that measures can be taken before they lead to accidents.

Multispectral satellite images are used for renaturation (restoring land to a nature-like state after mining) in mountainous areas because they can monitor vegetation conditions and so-called acid drainage (outflow of acidic water from iron ore and coal mines).

The data obtained make it possible to monitor the response of vegetation to stress factors with high temporal and spatial resolution. Therefore, image data is the basis for improved natural management. Satellite remote sensing and image analysis are also useful because of the possibility of agricultural or other economic activities on the land after mining.

02

How do satellite images map mineral territory?

There are more than 4,000 minerals on the earth. The amount of solar radiation reflected, transmitted and scattered by a particular mineral due to its chemical composition is unique. It is similar to a human fingerprint and is known as a spectral signature. The spectral characteristics of minerals can be determined from space by measuring tiny fluctuations in the length of electromagnetic waves with the help of satellites.

These machines allow to photograph areas of interest from space and interpret images taken in parts of the spectrum outside the visible range. For example, infrared and shortwave radiation data are used to identify structural features on the Earth's surface.

With spectral images and thematic mapping, researchers can obtain information about soil absorption and reflection properties, rock composition, and vegetation. The data can detect deposits of clay and oxides and determine soil types on satellite images.

In a study published in the African Journal of Geoscience in 2021, a team used remote sensing to map and quantify land cover change over time in the Wellcom-Virginia gold fields in South Africa. The study analyzed Landsat images from 1988 to 2018, with a five-year interval.

The study used geospatial indices, including the Normalized Differential Vegetation Index (NDVI), the Global Environmental Monitoring Index (GEMI) and the Normalized Differential Water Index (NDWI), to distinguish between different types of land cover. The images are classified by using the maximum likelihood method, a statistical method that estimates the parameters of a hypothetical probability distribution based on observed data, as well as supervised classification.

The results show that these indices are reliable for mapping and monitoring land use change and cover mining-related changes. Extremely accurate, up to 96%. Mapping land and use changes using satellite remote sensing and geospatial indices will help monitor the impact of mining on natural ecosystems and urban/residential areas.

03

Why is it important to map land and cover changes in the mining industry?

While mining is one of humanity's most important commercial activities, it has a huge problem: Global mining activities cause serious ecological damage. Carbon emissions, pollution, and land clearing of vital ecosystems are all harmful consequences of continued resource extraction. Arable land and vegetation cover are affected by open pit mining. Communities living near mining operations are affected both directly and indirectly.

Mapping land and cover changes resulting from mining operations facilitates planning, rehabilitation and mine closure. The data collected through monitoring efforts helps inform the future of the mining industry, identify any issues, and protect vulnerable ecosystems and communities.

Monitoring and mapping vegetation coverage is critical at all stages of the mine development and operation cycle. Vegetation maps help to assess the biodiversity of the area and, therefore, are often required during the planning stage of a mine. They help inform the best placement of mine structures, and information can establish a baseline for environmental damage. Changes in vegetation cover during operation indicate pollutant levels. After closing, it helps inform recovery progress and identify remaining contamination.

Mining activities have also changed the landscape, not only due to the mines themselves or pollution, but also due to infrastructure and the transport of materials by heavy machinery. This can cause significant physical changes in the surrounding geography in a short period of time. Can lead to erosion, land slides and disturbances in natural flood control systems, affecting a wider geographical area.

Remote sensing can also be used to monitor vegetation stress. Stresses include shortages or surpluses of water, insects, particulate and heavy metal pollution, acid rain and mineral deficiencies. Vegetation stress results in stunted growth, leaf pigmentation and changes in plant structure, plant death, and changes in vegetation types to more tolerant species.

Monitoring and mapping of land and surface changes directly or indirectly caused by mining activities is essential to limit the damage caused. Remote sensing plays a crucial role in these efforts.