EIACP (PC-RP) on Environmental Problems of Mining

K. G. Hosahalli Granite Quarry Blasting Accident

The quarry was being worked with HEMM comprising 115 mm DTH drills (2 nos.), 1.1 m hydraulic shovels (3 nos.), 8 t capacity cranes (5 nos.) and 8 t capacity tippers (3 nos.). The East Bottom Pit, which was the main working area, had four benches of 4 m, 2 m, 10m and 4 m height. The mine was worked only in one shift from 8.30 a.m. to 5.30 p.m. with a one-hour lunch break from 1.00 p.m. to 2.00 p.m. The average daily employment was about 150.

Method of work

The massive granite deposit was overlain by 1 m to 2 m thick alluvium. After removal of the alluvium, a block of about 30 m x 6m x 3 to 4 m (height) was prepared for excavation. In this block, first a set of 6 m long horizontal holes were drilled at intervals of 1 m. These horizontal holes were charged and blasted to induce a crack along the horizontal plane, the depth of the plane being 3 m to 4 m. Then using the jet burner, one side of the 30 m block with a width of 6 m was cut upto the depth of the horizontal cut. On the other side of the block, closely spaced drill holes were made with the DTH drill for the same width and depth. Thereafter, vertical holes were drilled upto the depth of the Horizontal crack in a grid of 3 m x 3 m upto the edge of face to prepare detachable blocks. These vertical holes were blasted with detonating cord in water-filled condition. This blast would induce a crack along the line of drilling. After blasting, the detached block was removed with the help of an excavator. The process was repeated till the block was fully excavated.

The method of charging and blasting of horizontal holes involved inserting the detonating cord upto the full length of the hole, then inserting 2 or 3 cartridges of 90% special gelatine and stemming with sand or muck cartridges upto the mouth of the hole. Ends of all the detonating cords were then tied to a trunk line and blasted with the help of ordinary detonators and safety fuse. Blowing of holes was done with a G.I. pipe. Charging was done with the help of a plastic pipe. Sometimes gun-powder was also used with special gelatine.

The accident

On 8.11.96 work started in the quarry in the usual way. At the East Bottom face, 26 horizontal holes of about 7 m length were kept drilled. The holes were cleaned by compressed air through a G.I. pipe and then each hole was charged with detonating cord upto full length, 200 g of gunpowder and three cartridges of 90% S.G. with the help of a plastic pipe. The holes were stemmed and blasted at about 1.30 p.m. and then the workers left for lunch. When they returned after lunch, it was found that adequate crack had not developed along the horizontal plane. Then the mistries & their co-workers started re-charging the holes with detonating cord and two cartridges of special gelatine and stemming the holes. At about 5.30 p.m. when the 26th hole was being charged, an explosive cartridge got stuck in the middle of the hole. They tried to push it with the plastic charging pipe but did not succeed. So they withdrew the plastic pipe and inserted the G.I. pipe into the hole and started pushing the explosive cartridge. Suddenly the explosive blasted and all the ten persons who were either holding the pipe or were standing around the place were thrown away amidst lot of, dust, missiles smoke and fumes. 3 persons died on the spot, the other seven received serious bodily injuries. One of the injured persons died on the way to Ramnagar Civil Hospital, the other six were given initial treatment at the Civil Hospital and then transferred to a private Nursing Home at Bangalore.

Observations

This accident brought out interesting details about the working of granite and other similar mines.

1. The first information regarding this accident was received at the Oorgaum regional office of DGMS on 18.12.1996 (that is, 40 days after the occurrence) through a letter from the mine manager in his personal capacity. Official notice in Form IV-A; and IV-B was submitted by the owner only on 1.1.1997 thereby causing a long delay in conducting the inquiry.
2. According to the notice of opening in Form-I, the mine was opened on 26.12.1994. A Mining diploma holder was appointed as manager with effect from 1.10.1996 but Notice of Appointment of Manager in Form-I was not sent to DGMS. He had not obtained even a Foreman’s exemption certificate. . The mine was being worked with heavy earth moving machinery which required appointment of a First Class Manager.
3. Blasting was being carried out in gross violation of the provisions of the MMR. Before re-charging shot-holes, the safe procedure as stipulated in MMR 167 and 168 to deal with sockets and misfires was not followed. A metallic pipe was used for pushing the cartridge in the shot-hole. The blaster was not present at the site when the shot-holes were being re-charged.

Although this was a reasonably large mine using HEMM and employing about 150 persons, there was gross violation of the safety laws either because of inadequate awareness or because of deliberate disregard of the laws. There might be more such mines which are worked in contravention of safety laws endangering the lives of innocent workers. Accidents in such mines might be going unreported. Such mines need to be brought into the system.