Finding buried steel debris at an open-pit mine with a drone magnetometer

The challenge

Loader bucket teeth, baseball-sized pieces of hardened steel, were mixing into the rock stream and damaging the crusher. The mine needed to scan rock piles for buried steel without stopping work. Rocky ground and heavy machinery made manual checks dangerous, and a handheld metal detector was ruled out because of the size of the area and the volume of rock. The method also had to give exact coordinates, so debris could be dug out before it reached the crusher.

The solution

The team set up a staging area and assembled the system:

• a DJI M300 carrying the payload, keeping people away from the debris field;
• a DJI RTK base station for precise target positions;
• a SENSYS MagDrone R3 fluxgate magnetometer, ready to fly within minutes;
• the SkyHub onboard computer for data logging and georeferencing;
• UgCS to plan and fly an automated grid in both X and Y directions.

A laser altimeter let the drone follow the terrain over the grid, and it returned to its start point automatically. First, steel samples were buried 6 inches deep. Then a loader buried targets at 1 to 5 m under crushed rock, from wallet-sized stones to boulders, and the same flight plan was flown again.

The results

• In the shallow test, target positions, depths and field strengths were mapped without issue.
• In the harder test, relatively small steel targets were found at depths of up to 3.5 m.
• The report notes that larger steel objects should be detectable deeper than 3.5 m.
• The RTK base gave precise positions, and the SENSYS software output listed coordinates and signal values for each target.

The workflow protects the crusher and removes the need for people to scan an active industrial area on foot.

Where this applies in India

• open-pit coal, iron ore and limestone mines that feed crushers;
• quarries and aggregate plants with recurring tramp-metal damage;
• stockpiles at cement and steel plants;
• hazard mapping for buried steel in other heavy industrial sites.

SPH Engineering's magnetometer training is also available through HobiTech.

The equipment, available from HobiTech

Magnetometer	SENSYS MagDrone R3
Onboard computer	SkyHub by SPH Engineering with the SkyHub MagDrone software and True Terrain Following
Flight planning	UgCS - Drone Flight Planning Software
Drone	DJI M300 with a DJI RTK base station was used in this project. Ask us for current compatible drones.

Case study by SPH Engineering, published March 2026. This page summarises it in our own words; the survey was carried out by Altomaxx, not by HobiTech. Read the original case study on SPH Engineering ↗