An eye in the mine: Hindustan Zinc using drones underground to dig deep

Sometime in 2017, drones flew through the Cannington silver and lead mine in Northwest Queensland, Australia. The drones came from Emesent, an Australian firm that pioneered the use of drone survey in underground mines, and offers a technology called Hoverman with functions such as collision avoidance, GPS-denied flight (in areas without GPS) and SLAM (Simultaneous Localisation and Mapping)-based LiDAR (Light Detection & Ranging) mapping.

What started in Australia two years ago, has now been introduced in India. In July 2019, the Vedanta Group-owned metals and mining major Hindustan Zinc Ltd (HZL) began deploying drones in its underground mines in Rajasthan to dig more value out of them. This makes it the first mining entity in Southeast Asia to use drones in underground mines, says the company, which has engaged Canada-based Clickmox, which has expertise in underground drone technology, to help it in its enterprise. 

“Our aim is to equip all our operations technologically to enhance safety and productivity. The prototype of a digital mine is already operational in our Sindesar Khurd mine. Autonomous drilling and haulage, remote-controlled operations, real-time asset tracking and mine monitoring are some of the features we intend to standardise across our mines in the coming three years,” says Sunil Duggal, CEO, HZL.

At present, trials are underway at HZL’s flagship Sindesar Khurd (SK) zinc-lead mines in Rajasthan. The trials began as a Proof of Concept (PoC) to check the data the drones captured and the value it could add to the company’s operations. Having rigorously pursued the trials and evaluated the results, the company believes the time is now ripe for a full-scale deployment and also to scale it up to its other mines.

“Based on the analysis, we can say that drones can now be applied on a larger scale. But trials will continue for many more months. SK and Agucha mines are the key, but we will roll out trials in other mines too,” says Barun Gorain, chief technology and innovation officer, HZL.

HZL is currently using line-of-sight drones while it waits to try fully autonomous drones by next year. 

HZL’s Ontario-based technology provider- Clickmox Solutions Inc is the first company to combine the power of 3D LiDAR scanning with the mobility of UAV (Unmanned Aerial Vehicles) technology for the underground mining environment. The company has now taken the technology a step further and is offering a complete digital mine solution.  

Drones deployed in mines can perform an array of functions — stope scanning, inspection of inaccessible areas, and convergence monitoring. General stope scanning is meant for accurate excavation audits whereas convergence monitoring is to determine bulking, which can potentially lead to cave-ins. The scanner mounted on the top of a drone uses LiDAR technology to scan the stope and capture an accurate image. After reaching the surface, the collected data is sent to a cloud-based software for processing and the backend team examines the data to arrive at exact geo-coordinates.

Drones are most helpful in areas that are inaccessible or unsafe due to inadequate ventilation. “In manual survey, you cannot cross the stope since there is the danger of rocks falling. But a drone can do this without any fuss. If you take an image of a conventional survey and compare it with a drone image, you will notice a huge difference,” Gorain explains.

Drone technology also helps capture more information on the recovery of ore and gives a closer look into the structural movements in mines. Their sensors can monitor temperature and humidity and record any anomalies, which is difficult to do otherwise.

Drones also trump traditional manual survey in mines when it comes to unearthing more value from them. For example, the quantum of ore that has actually been mined is difficult to determine using conventional technology. “But if we use drone technology, we can quantify the recovery with up to 70 per cent accuracy. Based on that information, you can improve your drill and blast method. You can recover more, and thus improve productivity,” says Gorain.

The conditions in underground mines are also very different from those in open pit or surface mines. At the SK and Agucha mines, digging is done at depths raging from 500 metres to 1 km. “That means the drones have to be designed specifically for underground mines and have to be sturdy,” says Gorain. 

This is where MineFly, a complete drone-based 3D laser scanning and mapping system specially designed for GPS-deprived areas, comes in. Compact and lightweight, this aerial drone comes with a 3D laser scanner, LED lighting, sonar sensors, an HD camera and several low-resolution cameras. The technology is based on Clickmox’s proprietary software, which generates the accurate “point (temporary) cloud”, which in turn generates the 3D map either in real-time or offline.  

HZL expects the benefits from drone technology to flow in straightaway. With the same or lower costs and lesser resources, the company anticipates a 20 per cent increase in its productivity once the drones are fully operational in its mines.