A relative is consoled after the retrieval of the bodies of two miners from Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNM27

A miner is transported on a stretcher by rescue workers after he was rescued from below ground in Johannesburg's oldest gold mine in Langlaagte, South Africa, September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNETD

ATTENTION EDITORS - VISUALS COVERAGE OF SCENES OF DEATH OR INJURY Relatives and friends bring to the surface the body of a miner after recovering it from Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNLP3

An entrance to an underground Johannesburg's oldest gold mine is seen in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCF0

Suspected illegal miners walk after they surfaced from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCF1

A miner looks into an entrance of Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNL36

A suspected illegal miner (C) is welcomed by friends and family members as he surfaces from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCEL

Relatives and friends of miners wait for the retrieval of bodies outside an entrance of Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNL31

Suspected illegal miners look on after they surfaced from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCEM

Relatives and friends of miners wait for the retrieval of bodies at an entrance of Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNL27

A police officer gestures to a suspected illegal miner after he surfaced from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCEK

Image used for illustrative purpose. A suspected illegal miner looks at the entrance of an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCFA

ATTENTION EDITORS - VISUALS COVERAGE OF SCENES OF DEATH OR INJURY A relative covers the body of a miner after it was retrieved from Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNLQR

A suspected illegal miner (C) is questioned by police after he emerged from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko - RTSNCDE

REFILE - CORRECTING GRAMMAR A suspected illegal miner (C) is questioned by police after he emerged from an underground Johannesburg's oldest gold mine in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko TPX IMAGES OF THE DAY - RTSNG66

Miners look on after they retrieved the bodies of two other miners from Johannesburg's oldest gold mine in Langlaagte, South Africa, September 13, 2016. REUTERS/Siphiwe Sibeko - RTSNM2G