* Rescuers reach eight miners in refuge area
* Another nine missing
* Chief executive oversees rescue effort (Updates with rescue of 8 trapped miners, union comment)
By Zandi Shabalala
DOORNKOP, South Africa, Feb 5 (Reuters) - South African emergency workers rescued eight miners trapped a mile underground on Wednesday by a fire and rock-fall at Harmony Gold's Doornkop mine near Johannesburg, but nine other workers remained unaccounted for.
Rescue teams had to battle through smoke and debris at a depth of 1,700 metres to reach the eight, who had managed to flee to a refuge bay equipped with a telephone and other survival items.
"Efforts continue to establish the whereabouts of a further nine employees who are currently unaccounted for," the company said in a statement.
Chief executive Graham Briggs cancelled a presentation at a major industry conference in Cape Town to fly to Johannesburg to oversee the rescue effort at the mine, 30 km (20 miles) west of Johannesburg. Normal mining operations were suspended.
The National Union of Mineworkers said the fire broke out on Tuesday evening after an earthquake that damaged ventilation and water pipes as well as power cables.
"The damage to the electric cables triggered the fire underground, which is still burning," it said in a statement.
South Africa's gold mines are the deepest in the world and ranked as some of the most dangerous during the apartheid years.
Since the end of white-minority rule in 1994 the government, unions and companies have worked hard to improve safety, but 112 people were still killed in the mines in 2012, the last year for which records are available.
At least 82 men - thought to have been illegal miners - died after an underground fire at a Harmony mine in 2009. Most of the victims are believed to have died of suffocation.
All miners carry emergency oxygen packs and rescue bays are equipped with food, water and breathing equipment in the event of prolonged underground entrapment. (Reporting by Zandi Shabalala and Ed Stoddard; Writing by Tiisetso Motsoeneng; Editing by Ed Cropley)