An around-the-clock search for eight miners in west Africa trapped more than 500 metres underground by floodwaters, three weeks ago, continues as rescuers pin their hope on new equipment to aid their efforts.
There has been no communication with the workers at the zinc mine in Burkina Faso since April 16, when heavy rainfall caused flash floods. Their location remains unknown, the Canadian owners of Perkoa Mine said.
The eight missing miners were working below Level 520, which is 520 metres (1,706 feet) from the surface, at the time of the flooding. Around 32 million litres of water have been drained from the mine and "access has been restored to Level 550", the company said.
There are two refuge chambers located below Level 520 in the event of miners becoming trapped, but the company said it did not know if any of the missing workers had been able to reach them.
In a statement, the company said it "continues to strengthen search capabilities with additional equipment and resources, and search crews will continue to work at maximum capacity, 24-hours-per-day to locate the missing individuals".
Burkina Faso prime minister Albert Ouedraogo said managers of the mine had been banned from leaving the country while investigations were underway into the cause of the accident.
Representatives of Trevali and Byrnecut, the mining contractor at Perkoa, said they are in daily communication with the families of the missing workers and continue to offer support.
"We are working in solidarity with all levels of government and as fast as we possibly can using all available resources in the country, as well as importing additional machinery and equipment to assist with locating our missing colleagues," said Ricus Grimbeek, President and CEO.
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"Our thoughts are with our colleagues' families, and we continue to work closely with the families and the government to ensure their needs are met during this difficult time."
He added: "We will remain closely engaged with government authorities to help the community respond to the impacts of the recent flooding."
The huge search effort has required rebuilding access ramps in order to install and operate pumping and piping infrastructure to remove floodwater using about 25,000 tonnes of waste rock. It has installed 5,000 metres of pipes and 24 electric and diesel pumps.
Perkoa zinc mine is located at Sanguie, 120km away from Burkina Faso's capital city Ouagadougo. It is the first large scale base metal mine in Burkina Faso.