"Window cleaning" device used to free trapped miners.
South African gold mines operate under extreme condition s of depth, rock pressure, and temperature. When accidents happen, these harsh conditions only complicate rescue and recovery operations. But as South Africa's mining industr has demonstrated, skill, ingenuity and a willingness to work together can overcome even the most difficult conditions faced in a mine emergency.
In October 1993, a hydropower water column failed at the Gold Fields of South Africa's Kloof mine. Some 150 workers were trapped 43 levels underground. A South African Government Mining Engineer's inquiry is still underway to determine the cause of the failure, but the successful, six-day rescue effort that followed is a classic example of a deep-mine rescue completed under the most difficult of conditions. This account of the rescue is based on an article first published in South African Mining World in April 1994 and appears with it kind permission. (See E&MJ, Dec. 1990, pp 22-25 for full details of the Kloof hydro-mining system.)
Around midday on Oct. 13, 1993, during the final commissioning of a hydropower system at Kloof's No. 3 sub-vertical shaft, the column failed just above level 27. About 260 m of piping dislodged and plunged down the shaft.
Fortunately, both man-cages in the path of the debris were empty and stationary One cage had been raised to level 31 a few minutes earlier, but its occupants had evacuated the area when they heard the crash and saw debris and water cascading down the shaft.
The falling pipes caused substantial damage to the conveyances and associated shaft steelwork, as well as to other shaft columns and bearers. Electric feeders, and signaling and telephone cables in the shaft were severed as well.
Fortunately, intercom telephone links were still operable down to level 35 via the No. 3B service shaft, so mine managers were able to learn that damage to station steelwork there prevented the use of normal cages in the rescue operation. Management instructed trapped workers on levels 33 through 35 to proceed to the No. 3B service shaft where, although power had been cut off, an escape ladderway was available to reach the level 31 bank. Once there, workers could use the main traveling haulage to the No. 1 sub-vertical shaft complex to be hoisted to the surface.
Kloof's Proto team was able to establish radio communications eventually to levels 35 through 39. Workers on levels 37 and 39 were directed to go to 35 via the reef horizon in longwall 21 and other prescribed routes.
Engineering and shaft teams also managed to commission one hoisting compartment in the shaft between levels 23 and 30, allowing use of a single-drum hoist. All travel until then had been done from the main shaft on level 31, so the additional compartment allowed for more workers to be rescued in less time.
Below level 35, however, workers were totally stranded. All communication was lost because the telephone cable had been damaged below level 31. Power, water, and compressed air services down the shaft were interrupted because power had been shut off from level 23 on down immediately following the accident.
At first rescuers tried removing the side-sheeting and floor panels of the bottom deck of the No. 1 man-cage (the only conveyance left operable) and using it more as an inspection platform to reach levels 35-43. That didn't work, however. At a point 28 m above the level 31 station, the cage became wedged within the guides, making further descent impossible. Another route had to be found.
In anticipation of such complications to the rescue, Kloof management had set u a control room and had been enlisting logistical support since the accident had occurred. Members of Rescue Training Services were called in to manage the rescue and coordinate the Proto teams, who started to pour in from as far away as the Free State and Evander gold fields. One of the biggest challenges for th rescue management team was keeping track of who and how many were still stranded. Because of the large number of contracting firms on the lower levels and the fact that many workers moved from level to level in the course of their duties, compiling a list of the missing was difficult but not impossible for th management team.
The morning after the accident, another method of rescuing the miners trapped i levels 35 through 39 finally arrived. A borehole rescue winch was brought in from Evander Rescue Training Services' station and was mounted in modified form on level 35. This allowed access through the broken steelwork in the shaft, dow to level 41.
The real breakthrough in the rescue efforts, however, came when the Proto teams arrived at the level 39 station and set up a Rollgliss apparatus, a portable climbing system that uses a nylon rope and a clutch to manually carry people. Using the Rollgliss apparatus, a single team member was able to reach level 41. He then reported to the surface that all workers there were accounted for and were in good health. One at a time, the miners were lifted to level 39 to make the journey to the surface.
Back on level 35, another team member was lowered by the rescue winch a hazardous 280 m through the damaged shaft steelwork to the level station on 39. A Rollgliss was then used to drop a rescuer to level 43, the bottom operating level of the shaft. He also reported good news: All were accounted for and in good health.
Just after 10 p.m. on Thursday night, another Proto team including paramedics made its way down to level 43. After checking the health of the workers, they managed to establish an escape route away from the loose steelwork in the shaft by clearing rock from the mouth of a lined orepass. A Rollgliss was set up abov the orepass, and the first man was hoisted up to level 41 in the early hours of Friday morning.
The rescue was progressing, yes, but too slowly. At a rate of only one man per hour, a quicker means of evacuating workers had to be found. Fred Bear, engineering manager at Kloof, came up with the answer: an electrical rope-climbing device of the type used to clean windows on tall buildings. A local company, Skyjacks, had adapted this appliance for use in shaft work. A rope, connected to a man-carrying cage or platform, is pulled through an electric rope hoist. The rope is not rolled onto a drum, so its length is not limited. Called a Sky Climber, the device could be powered by a portable generator and was light enough to be carried the distance to level 39. It would work to reach the depths required for the rescue.
By Friday evening, four Sky Climbers were on there way underground. Bosun's chairs, shaped like bullets, were manufactured in the mine's workshops, and these too went underground with diesel, ropes, controls, and wiring for the Sky Climbers. Once the Climbers were in place, the evacuation rate greatly improved An additional escape route was established in an upcast ventilation raise between levels 39 and 41, and another Sky Climber replaced the laborious Rollgliss hoisting between levels 41 and 43.
This leg of the operation occupied the rescue teams fully through Sunday, Oct. 17, by which time the rate of evacuation was three men per hour. With the aid o the Sky Climbers, workers were received on level 39, given medical check-ups an dispatched to surface at regular intervals.
By midday on Tuesday, Oct. 19 -- a full six days from when the accident occurre -- the last men were welcomed to surface; they were five supervisors who had remained to ensure that their workmen were rescued.
There were no casualties amongst the trapped men or the rescue team members. Sadly, one Kloof miner, Vivien Mbhele, died of medical complications while volunteering his services to help carry food and water underground to his fello miners.
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|Publication:||E&MJ - Engineering & Mining Journal|
|Date:||Sep 1, 1994|
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