A worker operates remote-controlled facilities at the Baodian Coal Mine. [Photo provided to China Daily]

On a visit to a coal mine four years ago, I interviewed a group of college graduates who decided to become miners. They were working underground in grim conditions.

In contrast, the mine I visited recently showcased the advantages brought by a range of smart technologies.

In the middle of last month, I joined miners as they descended to a coalface at the Baodian Coal Mine in Shandong province, which is operated by the Shandong Energy Group.

The miners' faces were scanned as they opened lockers containing their work clothes, shoes, helmets, helmet lamps and self-rescue devices.

They told me that a system providing real-time location monitoring is built into their helmet lamps. Workers can be located from the control room by smart monitoring software, which provides vital data for search and rescue teams in the event of an emergency.

After changing into work clothes and collecting their equipment, the miners scanned their faces again to pass through a security gate.

From that moment on, the names, location and number of miners at the coalface are displayed on a screen in the control room. If the smart system finds that any of them have been drinking alcohol, they are denied entry.

After negotiating the security gate, we took an elevator and descended for about four minutes to a depth of 430 meters, where we found ourselves in a brightly lit passageway.

Here, we encountered strong gusts from the smart ventilation system, which Niu Qingjun, the team leader working at the coalface, said was installed at the mine in August.

Ventilation is crucial to working underground. To provide the miners with a safe operating environment, the smart system enables the real-time provision of fresh air and disperses hazardous gases. It can also supply air according to requirements at the mine, resulting in significant savings in both energy and cost.

Niu said if hazardous gases underground reach the maximum level, the system sends warnings and cuts the electricity.

Before the system was installed, workers used to check the air by using manual devices.

Walking along the passageway, we entered a room where the miners wait for trucks to take them to the coalface.

We used a car, and it took us about 20 minutes to travel the 3.5 kilometers to the coalface, which is more than 500 meters underground.

At the mine I visited in 2016, workers used seats on a conveyer system nicknamed the "monkey car", before walking a long distance to the coalface.

As our car came to a halt, I noticed a control room, where screens on the wall monitor machines digging, collecting and transporting the coal.

Cutting machines used at the coalface have memory and the ability to restart their work at the point where they stopped.

Niu said there used to be more than 20 workers at the coalface, but now only seven are required, thanks to the automation and smart operations.

In addition to the control room, I saw an area where 5G technology enables smart equipment to work in real time.

Niu shared the 5G network on his phone with me. Even though we were underground, the images I sent to a friend were transmitted faster than using 4G above ground.

I believe that 5G technology, which offers faster data transmission, will contribute to safe production at mines, because in the event of an accident, every second counts for rescue workers.