The Parcoa mine, owned by Canadian firm Travel Mining Corporation (TV.TO) and located about 120 kilometers (75 miles) west of the capital Ouagadougou, sank abruptly on April 16 after unexpectedly heavy rains during the country’s dry season.
During a month-long search and rescue operation, there was little hope that the missing could reach the rescue chamber, which has food and water supplies and is located about 570 meters below the ground.
“Rescue teams have opened the refugee chamber, unfortunately it is empty,” the government information service said in a statement posted on social media.
Trevali said the shelter chamber had been found intact and it was now clear that none of the eight missing workers had reached there.
“This is devastating news, and we would like to extend our deepest sympathies to the family and friends of our colleagues at this difficult time,” said Rikas Grimbic, president and CEO of Trivali, in a statement.
“We will continue our search efforts and reiterate our commitment to work at full speed to find our colleagues.”
Troubled relatives of the missing are gathering at the site in Sangui prefecture every day, seeking solace from each other as they face a painful wait for news.
Fatal mining accidents are common in Africa. The Percoa floods garnered more attention than many because, far from it, a dramatic 2010 rescue in Chile of 33 miners who spent 69 days underground – but not supposed to happen.
Both the company and the government have begun investigating the cause of the disaster. The prime minister said on May 2 that mine managers had been banned from leaving the country.
The bottom of the Perkoa mine consists of an open hole with an underground shaft and gallery. Most of the workers were able to escape during the flash floods, but the eight missing were 520 meters (1,706 feet) below the surface.
Among the missing are six Burkina Faso nationals, a Tanzanian and a Zambian national.
While many in Burkina Faso have been asked why it took so long to get to the rescue chamber and mount criticism of the company and state emergency services, Trevali said there were plenty of technical challenges.
The flood was so violent that it washed away the road to the mine and damaged the power supply. The road had to be rebuilt and electricity restored before the full scale search could begin.
Initially, the equipment was lowered on foot, but vehicles were needed to install equipment capable of pumping water from depths below 500 meters.
Rescuers pumped about 55 million liters of flood water, an estimated 165 million liters of which flowed through the mine’s underground.