EIACP (PC-RP) on Environmental Problems of Mining

Champion Reef Gold Mine

The accident occurred in the Biddick’s shaft which was an auxiliary shaft sunk from the 70th level to 9 m below 103rd level, the total depth from the 70th level being 969 m. The shaft was elliptical in shape, 5.33 m (north-south) by 3.66 m (east-west) and was concrete lined except between 86 and 88 levels where it was lined with brickwork. This was the main hoisting and traveling shaft for the northern section of the mine.

The concrete lining was 60 cm thick with every 2.4 m of concrete lining alternating with 0.6 m of brick and granite masonry. The shaft had been subjected to a number of movements since 1941, the maximum trouble having been experienced between 80 and 86 levels. In this zone the shaft had been relined at some places more than once.

On 27.5.1955 at about 9.20 a.m., as the south cage containing men on its downward journey had stopped at 91 level to allow 3 persons to get out, a slight rock-burst took place and a portion of the shaft lining measuring approximately 6 m x 3 m x 0.9 m collapsed from about 4.5 m above the 87 plat and fell on the cage from a height of 115 m. The cage was badly damaged; 10 of the occupants died instantly and the remaining 8 persons were seriously injured.

The shaft appeared to have been sunk in an area which had high inherent stress. It was thought that earlier rock-bursts might have damaged the lining inside and the damage might not have been visible during the routine shaft inspections.

The Inspecting officer who inquired into this accident made the following recommendations:

1. The flat roofs of the cages should be replaced by sloped roofs made of 4.8 mm thick mild steel sheets properly strengthened.
2. Deep shafts in highly stressed ground should be inspected daily by the Road Foreman.
3. Shaft inspection report should give full details of the extension of old cracks and the occurrences of new cracks.
4. The shaft lining between 80 and 82 levels which had developed a number of cracks should be thoroughly repaired with cement and rock bolts before the shaft is put into use.

The management decided to further reinforce the shaft lining by installing rows of wedge type rock bolts, 1.5 m long and 25 mm in diameter with 230 mm square plates on the periphery of the shaft at intervals of 3m. The accident was classified as a case of “misadventure” because it occurred in spite of due diligence on the part of all concerned.