China’s Powerful Deep-Earth Mining: 500-tonne ‘underground carrier’ tunnels a kilometre

• “Gangtie Jiliang” is the first machine capable of drilling full-face vertical shafts beyond 1,000 metres in hard rock.

• Developed by CRCC, the 500-tonne giant is now operating in Liaoning.

• Deep mineral reserves may far exceed surface deposits, including antimony, gold, tungsten and lithium.

• Advanced muck removal and real-time reinforcement improve safety.

• Technology supports China’s long-term resource and strategic infrastructure goals.

A formidable new machine with an equally commanding name is set to transform how humanity reaches into the Earth. Known as “Gangtie Jiliang,” or “Steel Backbone,” the colossal device has been engineered to drill vertically into hard rock to depths previously considered out of reach.

Described as the first machine in the world capable of boring full-face vertical shafts beyond 1,000 metres (3,280 feet) in solid rock, the 500-tonne structure stretches 8.1 metres across. Its sheer size and complexity have prompted observers, including China’s state-run Science and Technology Daily, to liken it to an “underground aircraft carrier” rather than conventional mining equipment.

Developed by the China Railway Construction Corporation (CRCC), the machine has moved from a record-setting assembly phase into active deployment. It is currently operating at an iron ore site in Liaoning province in northeastern China, where it is tasked with accessing mineral deposits buried deep beneath the surface.

Vast Wealth Below the Surface

China’s push into deep-earth exploration is driven by striking geological estimates. Specialists believe that mineral reserves located far below ground could be double the volume of those already identified near the surface.

Data from the China Geological Survey in 2018 suggested that antimony deposits found at depths reaching 2,000 metres could be more than five times greater than currently proven reserves. Antimony plays a key role in battery production, semiconductor manufacturing, and specialized metal alloys.

Other minerals show similar potential. Deep-level reserves of lead, zinc, and gold are estimated to be roughly quadruple those found in shallower layers. Tungsten — prized for its density and essential applications in aerospace and defence industries — is believed to exist in deep deposits at three times the volume of surface-level resources. Comparable ratios apply to lithium, rare earth elements, and coal.

While miners have extracted minerals from near-surface deposits for generations, many of the most accessible sources are now exhausted. Reaching deeper reserves has therefore become a strategic necessity.

Engineering for the Deep

Unlike traditional drilling methods, which often rely on blasting and incremental excavation, Gangtie Jiliang is purpose-built for vertical penetration through hard rock formations. At its core is a massive circular cutterhead that spans the entire diameter of the shaft. The system drills downward from the surface in a continuous operation, similar in principle to a giant vertical drill.

According to chief designer Ding Zhangfei, the development process involved overcoming several formidable technical challenges, leading to multiple patented innovations.

One of the most difficult obstacles was managing the removal of excavated rock. In horizontal tunneling, debris can be transported away along the tunnel floor. In vertical drilling, however, gravity causes broken rock to gather directly beneath the cutting head, complicating removal efforts. Engineers reportedly spent nearly half a year testing different approaches before achieving a workable solution.

The breakthrough came from an unexpected source. During a visit to a wetland park in Changsha, the team encountered a traditional dragon-bone waterwheel — an ancient Chinese irrigation device dating back more than two millennia. Inspired by its structure, engineers devised an intelligent vertical transport system modeled on the same mechanical principles. The resulting muck-removal system can move as much material per hour as 10 trucks operating simultaneously.

Reinforcing Against Nature’s Pressure

Digging a kilometre or more underground introduces additional dangers. High ground stress and elevated water pressure can cause freshly cut rock walls to deform or collapse almost immediately — a phenomenon sometimes described as the “safety curse” of deep construction.

To address this, CRCC collaborated with several domestic research institutions to develop a real-time reinforcement method. The system stabilizes shaft walls as excavation progresses, reducing the risk of structural failure in extreme subterranean conditions.

Strategic Implications

The urgency behind such innovation has been underscored by academic research. A 2022 paper published in Strategic Study of Chinese Academy of Engineering noted that as shallow mineral reserves decline, China’s mining sector must increasingly target deposits located more than 1,000 metres below ground to maintain long-term output.

The country already operates more than 40 coal shafts and nearly 20 metal mining shafts that exceed 1,000 metres in depth, with seven extending beyond 1,500 metres. However, conventional drilling-and-blasting techniques pose significant safety risks in such environments. Researchers have therefore called for rapid development of advanced, automated equipment to improve both efficiency and worker protection.

Beyond resource extraction, the implications of deep-shaft technology may extend into national infrastructure. Some Chinese energy specialists have proposed constructing underground networks in western regions of the country to safeguard key energy and defence installations. Embedding critical facilities deep below ground could enhance security while reducing detectability.

As Gangtie Jiliang begins its operations, it signals not only a new chapter in mining technology but also a broader strategic shift toward the depths. In the race to secure future resources and infrastructure, the Earth’s hidden layers are fast becoming the next frontier.