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The Role of Magnetometry in Advancing Mineral Exploration

Integrated Systems
August 28, 2023

Welcome to the series of articles centered around Drone for Mining, where we delve into the uses, advantages, constraints, and strategies for incorporating drones and airborne sensors within the mining sector. To illuminate this subject, we invited two experts to the discussion: Trevor Grace, Director at AeroPhysx Company, and Dr. Janis Karuss, Lead Geophysicist at SPH Engineering.

In the world of mineral exploration, searching for valuable deposits requires advanced techniques and tools. One such tool is magnetometry, which utilizes the Earth's magnetic field to identify potential mineral resources.

"Magnetometry in Mineral Exploration" is the topic we will dive into in this article. In the upcoming articles, we will dive deeper into specific applications, advanced techniques, and case studies highlighting drone-based magnetometry's transformative power. Join SPH Engineering and discover new possibilities for mineral exploration.

Magnetometry, in simple terms, involves measuring the strength of the Earth's magnetic field at various locations. The magnetic field is not uniform globally; it exhibits variations and anomalies. These anomalies can be attributed to objects beneath the Earth's surface with magnetic properties. For instance, large ore bodies or metallic structures underground can alter the magnetic field in their vicinity. We gain insights into geological properties and potential mineral deposits by meticulously mapping these magnetic anomalies.

"Choosing the right survey methods"

When it comes to mineral exploration, magnetometry proves highly useful. Certain minerals, like iron or nickel, exhibit strong magnetic properties, making them detectable through magnetometry surveys. Additionally, minerals without inherent magnetic properties can still be identified indirectly by the changes they cause in the surrounding magnetic field. Dr. Karuss emphasizes that it is challenging to create an exhaustive list of minerals that can be discovered using this method, as the focus is on identifying magnetic signatures that deviate from the norm, indicating potential areas of interest.

During our discussion, Trevor Grace also added that magnetometry does not directly detect minerals. Instead, it maps out the geological structures that influence the magnetic field. By understanding the magnetic response of specific geological formations or fault lines, mineral exploration teams can strategically plan future drilling locations along these paths. The information provided by magnetometry assists geologists in making informed decisions and optimizing their exploration projects.

Over the years, the methods of magnetic surveying have evolved to meet the demands of mineral exploration. Trevor Grace insists on the importance of close collaboration between clients and geologists to establish clear objectives and realistic expectations. While magnetic surveying cannot directly pinpoint minerals, it can isolate areas of interest within the magnetic structure. Factors such as line spacing resolution, linear versus nonlinear structures, and flying height in airborne surveys all come into play. Designing an effective survey strategy requires careful consideration of budget constraints, target identification, and the desired level of detail.

Recently, Drone-based magnetometry has been increasingly used in Mineral Exploration which involves using drones equipped with magnetometers to map the Earth's magnetic field. Compared to other methods, such as ground-based surveys or satellite-based measurements, drone-based magnetometry offers unique advantages and limitations. According to Dr. Janis Karuss, this method provides a cost-effective solution for covering medium-sized areas that are challenging to access on foot or by larger aircraft. It offers a middle ground between ground-based and standard airborne magnetometry, providing better resolution and lower costs than the latter.

When it comes to the size of areas that can be effectively surveyed using drone-based magnetometry, Dr. Karuss suggests that a few square kilometers are within a reasonable range. Larger areas, such as country-sized regions, may require alternative approaches due to budget considerations. However, the ability to access remote and inaccessible locations makes drone-based magnetometry a valuable tool in mineral exploration.

Trevor Grace emphasizes the significance of resolution in drone-based surveys. By flying at lower altitudes, drones can capture data with unmatched precision. With modern technology, high sample rates of up to 1000 Hz can be achieved, resulting in data that surpasses regional surveys in quality. This level of resolution is particularly advantageous in mountainous terrains, where conventional aircraft face limitations due to safety concerns.

Despite its benefits, drone-based magnetometry also has its limitations. Trevor Grace highlights the challenges of operating in large and inaccessible areas or when simultaneous gamma-ray surveys are required. Weight limitations constrain endurance, making it logistically challenging to cover extensive regions. Moreover, the presence of risks, such as encounters with dangerous animals, difficult terrains, or hostile locals, requires careful planning and emergency procedures.

Dr. Janis Karuss adds that climate and weather conditions can impact drone operations, particularly in polar regions where sudden strong winds and adverse weather changes can jeopardize the equipment. Although certain drones are more resilient to such conditions, it remains a limitation to consider when choosing the right approach.

In conclusion

Magnetometry, an invaluable tool in mineral exploration, involves identifying magnetic anomalies through measurement and analysis of the Earth's magnetic field. These anomalies stem from geological structures or mineral deposits. While not a direct mineral detection method, magnetometry imparts crucial data for project guidance and resource optimization.

Drone-based magnetometry significantly advances mineral exploration. Its benefits encompass access to remote areas, higher survey resolution than ground-based methods, cost and time savings versus traditional airborne approaches, and enhanced operator safety. However, challenges arise with vast or inaccessible regions, weight limitations, and the impact of weather and climate conditions.

The insights from Trevor Grace and Dr. Janis Karuss provide a comprehensive understanding of magnetometry's applications, benefits, and limitations in mineral exploration. This knowledge equips mining experts to elevate their utilization of magnetometry effectively.

As technology advances, the mining sector can capitalize on drone-based magnetometry's potential, enhancing exploration, resource allocation, and decision-making. With a clear grasp of its capabilities and constraints, mining professionals can judiciously integrate drone-based magnetometry into their practices, fostering advancements in mineral exploration.

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