The blast at the Liushenyu shaft in Shanxi province on Friday killed 82 people -- the country's worst mining disaster in nearly two decades, but the incident is not unique.

Here is what to know about China's mining safety issues:

- How does China regulate mining? -

In the early 2000s, accidents were common in China's mining sector, with thousands of miner deaths reported annually.

The crisis coincided with rapid economic development in the country, while the large-scale collection of coal it required was chronically underregulated.

Starting from around 2005, strengthened regulations and mass industrial consolidation that closed many small, private mines significantly reduced deaths.

Since coming to power more than a decade ago, Xi has bolstered enforcement, cracking down on lax mining officials and operators -- part of a broader campaign against corruption.

A dedicated government administration for mine safety was established in 2020.

But deadly incidents persisted, including the 2023 collapse of an open pit coal mine in northern Inner Mongolia, which killed 53 people.

- What are the allegations against this mine? -

Authorities have launched an investigation into the explosion at Liushenyu, saying preliminary findings showed the Tongzhou Group operating the mine had committed "serious illegal violations".

"Those found responsible will be severely punished in accordance with laws and regulations," officials told a news conference broadcast on state-run CCTV.

Miners working at the site accused their employer of a lack of care, telling AFP they had used their own money to purchase safety helmets.

AFP has contacted Tongzhou Group for comment.

State media have said that more than half of the workers in the shaft on Friday had gone down without being properly registered.

Miners are normally required to undergo facial recognition checks or take location-tracking cards before their descent.

A person "responsible for" the company had been "placed under control in accordance with the law", state news agency Xinhua reported.

- Crackdown coming? -

The latest disaster is likely to trigger renewed scrutiny of mine safety in China.

After the 2023 disaster in Inner Mongolia, authorities released a set of guidelines banning smaller coal mines and calling for investment in safer technology, including robots.

This time, Xi has called for a "thorough" investigation into the cause, noting that officials "must learn from the accident" and "intensify efforts to identify and eliminate potential risks".

But the timing of a potential crackdown on coal is complicated by the more precarious balance of China's energy supply amid the US-Iran war.

With oil imports still disrupted by conflict around the crucial Strait of Hormuz, coal could play a greater role in the country's power production this summer, when demand peaks.

Experts have observed that many past accidents stemmed from operators cutting corners, falling short of safety standards while under pressure to maintain high output.

- How important is coal? -

While China's massive economy has shifted in recent decades towards cleaner energy sources, coal remains a vital source of power.

The combined installed capacity of the country's wind and solar surpassed coal for the first time last year, as the fuel continues to play a key backup role in the transition.

It is also a natural, domestic source of power generation, contributing to President Xi Jinping's strategic plans for energy independence.

With China's oil supply highly dependent on imports, leaders have sought to diversify, while maintaining "the prevailing view of coal as the bedrock of energy security", a report last year by energy think tank Ember said.

In and around Shanxi, where Friday's explosion occurred, coal serves as the traditional backbone of the local economy, in contrast to the more high-tech and export-oriented coastal provinces.