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Making Russian mines safer

ITS ranking as one of the top five most dangerous countries for underground coal miners is not a statistic the Russian coal industry is proud of. The current safety focus of the country’s industry is on reducing coal dust and methane explosions, the main causes of fatal accidents according to an article in Moscow-produced <i>Russian Mining</i> magazine.*

Staff Reporter
Making Russian mines safer

The article pointed out that methane and coal dust explosions, as well as underground fires remain the main causes of coal mine accidents in Russia’s underground coal mining sector.

Frighteningly, despite dramatic technology improvements accident rate statistics have remained largely unchanged over the last 100 years. Data on mine explosions for 1904-1906 indicated 5-10 accidents per year. This is little unchanged with statistics gathered over the last ten years indicating average rates for explosions number seven per year.

On the positive side, the frequency of accidents is decreasing. In 1999 the Russian industry recorded 19 accidents related to fires; in 2003 this had more than halved to eight. The rate of collapse has however increased from five in 1999 to six in 2003.

In recent years Russia’s coal industry has undergone major restructuring. During 2001-03 the number of operating underground coal mines decreased from 139 to 110 while open-cut operations increased from 86 to 125. Of the 270 million tonnes of coal produced by the country in 2003, 112.3Mt, or 41.6%, was produced by underground mines. This was the first time underground coal output exceeded 100Mt, attributed to growth in mines operating one to two longwall faces.

Inadequate ventilation systems are one of the biggest challenges facing the industry with the country’s fan system described as being in a state of disrepair and operating in violation of safety standards. Some 60% of Russian coal mines use forced ventilation systems, while 31% use a combination of exhaust and forced ventilation and 9% use exhaust ventilation only.

Some scary statistics include the following: 31% of the total ventilation systems in operation have been working for over 25 years; maintenance requirements for 18% of these systems are not met (12 of these 42 systems have not had required biannual inspections for over ten years); nearly 35% operate with no reserve available and are thus unable to supply additional air in line with increased production or in the event of an emergency; and, 34% operate with no recording instruments for air pressure drop and supply control.

Air loss from leakage is typically high and to compensate some 20% of air supplied is in excess of applicable standards. This over-ventilation of coal faces and development headings contributes to heating of the coal and the formation of spontaneous combustion. In some instances return air from development headings finds its way to coal faces or other development headings. Half of the mines where this occurs are susceptible to sudden outbursts of coal and gas while some are designated very gassy mines.

Inadequate mine planning at the design stage is believed to be the major cause for the unsatisfactory ventilation of most Russian coal mines. This is partly a result of inadequate funding and coal sector restructuring that has resulted in a loss of skilled personnel.

The lack of investment in the coal industry has lead to a situation where design principles or proven operating methods have been altered, creating risks. Similarly, the coal industry has also suffered from a decrease in funding for research and development. Mine planning and design companies have no funds to conduct field trials leaving no way to ascertain safety in terms of changed design objectives.

In terms of methane gas management, around 80% of Russia’s underground mines are gassy and around 32% have a gas content of over three cubic metres per minute. Degassing systems in underground Russian coal mines are typically inefficient and not widespread.

In some mines, gas-suction ventilation is used to manage emissions mined out areas but in many cases this is inadequate. No consideration is given to the effect of gas-suction fans on gas conditions in the goaf which needs to be intensively ventilated for this method to work. Thus, as the longwall retreats the distance between the face and an installation roadway increases. As the face leaves the zone affected by the fan the air pressure drops but the fan continues to operate in the same way.

In the Kuznetsk basin, 15 such fan installations are used in seams prone to spontaneous combustion, dramatically increasing the risk of endogenous fires.

Furthermore, the stoppings used in cross-cuts between operating workings and gas drainage systems are not blastproof. Gas explosions at several Russian coal mines such as the Komsomolets in 2000, in which 12 miners were killed, and the 2004 disaster at Taizhina, with 47 dead, are evidence of the need for separating mine out areas from gas drainage systems.

Of growing concern is the increasing number of dip-working panels – where coal is mined under the main haulage level. Since 1991, 30 gas explosions have occurred at dip-working panel mines, killing 218 miners.

Mines using this method number 78 in 2004. They are either ventilated with a brake incline ventilation pattern or an incline ventilation patter. Both however are characterized by low aerological safety due to the presence of cross-cuts between workings.

In the case of fire the reversal of air flow in cross-cut occurs under the effect of the thermal drop of ventilation pressure which could flood all the workings of a dip-working panel. In these conditions it is impossible to evacuate personnel safely.

Developing and implementing a new safety ethos for Russian mines is clearly a pressing issue.

* Article based on Russia: Safety-in-coal mining, published in Russian Mining, No 3 2004.

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