Pimachova Alla "Prevention of endogenous fires in mine roadways equipped with belt conveyers" Dissertation

Pimachova Alla Grigorievna

Faculty: "Heotechnologiy and control development"
Specialty: "Safety of labour activity"
Theme of dissertation: "Prevention of endogenous fires in mine roadways equipped with belt conveyers"
Scientific leader: Doctor of technical sciences, professor, head of the Labour safety chair, dean of Mining faculty Bulgakov Y. F..

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ABSTRACT of thesis of DISSERTATION on a theme.

Topicality:

Development of fire-protection of mine workings equipped with belt conveyors is a topical scientific and technical problem. These roadways have high fire danger – combustible conveyor belt, wooden lining, mineral oil, electric cables. According to statistics every fifth exogenous fire takes place in belt conveyors. These fires are especially dangerous because they are spread quickly. This leads to huge material losses and deaths. During the last 10 years at belt conveyors only 20% of underground mines were put out at their initial stage.

Aim and tasks of the research:

To analyse the reasons of occurrence and development of exogenous fires at the mine of Ukraine. Grounding of fire-extinguishing installations in power-drive stations at mine "Krasnolimanskaya"

Scientific novelty:
According to research of SRI named after A.A.Skochinsky the reasons of exogenous fires are:

short-circuit (41,2%).
friction (slippage) of conveyor belts (31,6%).
breakdown [1] , including:
- during drilling and blasting operations (4,6%),
- during extraction (4,1%),
- unknown reasons (10,7).
Friction in machines and mechanisms (7,8%).

Damage from underground fires in coal-mining industry made 27% of the total number of accidents and became a dominant one.
Thus we can conclude the most fire-dangerous are roadways equipped with belt conveyors. These roadways have high fire danger – combustible conveyor belt, wooden lining, mineral oil, electric cables.

Statistics shows that only 18% of all fires were extinguished at initial stages, all others led to serious consequences, including people’s death (“Yuzhodonbasskaya” №1 “Donetskugol”, “Sukhodolskaya-Vostochnaya” “Krasnodonugol”). The figures show that despite the decrease of coal production the number of exogenous fires increases. Annually in Ukraine between 50 and 80 underground exogenous fires take place. They cause material loss in total 20-40 mln hrn a year. This conditions the necessity to generalize home and foreign experience in underground fire extinguishing in order to define progressive tendencies, developing and improving which it is possible to increase fire-extinguishing efficiency significantly. One of the main reasons of fire occurrence in belt conveyors is their low technical servicing, insufficient reliability of fire-safety.

Practical value and realization of the received results:

At present most Ukrainian mines use belt conveyors to transport coal to insets. This tendency will grow in future. However use of conveyors increases significantly fire-load of mine roadways, thus increasing fire-risk.
At present most Ukrainian mines use belt conveyors to transport coal to insets. This tendency will grow in future. However use of conveyors increases significantly fire-load of mine roadways, thus increasing fire-risk.

Among the automatic means of fire-extinguishing the most popular is water fire-extinguishing installation (WFEI). It is produced in Ukraine in three variants. It is able to protect head sections of all kinds of belt conveyors.
At “Krasnolimanskaya” mine at each conveyor drive head there is WFEI, as it is most efficient to be used at head sections of belt conveyors with one or two conveyor head pulleys with the help of water ring, produced by the sprayed water.

pict1 – fire-extinguishing installation (WFEI)
When fire starts and the surrounding air temperature increases the threshold of action, a fire-alarm box goes off and sends a sound electric impulse to the starter, in the result of which the heater is energized. The thread melts, pipeline switch plunger is pushed and water is fed to sprinklers. Water is sprayed and fire is put out.

It is necessary to note that at drive pulleys 24% of fires occur. They had to be extinguished by automatic installations on condition of their high reliability and efficiency. As is seen from information material from scientific and research institute in many cases WFEI did not function in a proper way due t their unsatisfactory condition. In WFEI there are a lot of electronic devices which are often stolen. Because of this it loses its efficiency.

That is why coal industry has to transfer not to progressive methods of fire-extinguishing, but to regressive, i.e. to mechanical-hydraulic starting WFEI. In case of emergency and absence of staff WFEI can be started automatically, which decreases the risk of further fire spreading.

General methods of research:

The following methods are used to develop theoretical ones, determine dependences defining basic parameters of fixed water-extinguishing installations, and to assess installations efficiency: mathematical statistics, theory of experimental design, modeling, mathematical analysis, classical physics, hydromechanics, aerodynamics, and theoretical mechanics.

Conclusion.

Patterns of water filling of step pipeline with uneven perforation and change of water flow speed at extinguishing installation starting have been defined analytically.

Practical value of the received results is that they are used as a base for calculating basic parameters of water fire-extinguishing installations and recommendations on their operational efficiency increase. Practical use of the method and recommendations will allow to develop new installations and modernize the present ones, which will provide efficient fire-protection in mine roadways with belt conveyors without reconstruction of the existing mine fire-irrigation pipelines.

Development of fire-protection of mine workings equipped with belt conveyors is a topical scientific and technical problem