In.: Proc. International Ming Tech. Symposium, Chongqing/ China October 1998,
China Coal Industry Publishing House (ISBN 7-5020-1651-1/TD8), p.266-271 (English)
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FIRE FIGHTING TECHNOLOGY AND DEVELOPMENT
IN CHINESE COAL MINES
Liu Yuanmin1
& Jiang Shicai1
ABSTRACT
This thesis elaborate the appraise method of our country’s coal spontaneous combustion tendency — coal
spontaneous combustion tendency rank and spontaneous combustion period in recently years and introduce
emphatically one method of measuring the shortest spontaneous combustion period with piling coal experiment
fittings and the other method of working out the shortest spontaneous combustion period by means of the heat
balance equation mathematical model regarded the oxidation reaction heat and oxygen uptake as basic
parameter.
Based on introducing manual sampling analytical method and taking advantage of mining environment monitor
system to monitor continuously coal mining fire parameter and to forecast or predication spontaneous
combustion , this paper deal emphatically with the normal type and the flameproof type beam tube bundle mine
fire monitor system developed in' the passed few years. In point of the technical of detecting hidden fire source
location in gob, this paper expose temperature monitor buried method, geologic method and radon
measurement method which have been tried in the passed few years to solution this problem.
“Two lines
two belts and two roadways” of coal face are the important positions to prevent and control
spontaneous combustion. Recently, according to the development of fully mechanized caving method rapidly,
spontaneous combustion of gate road becomes frequent increasingly. This thesis deal emphatically with the
speed coagulant or gelatinize fire fighting material ,leakage preventing equipment and underground movable
way、 ground movable way and ground fixed way nitrogen produce equipment. Point at the characteristic of
coal mining, this paper introduce emphatically the conveyer belt fire fighting technique and equipment, the
external fire disaster air current controlling method and the roadway fire fighting technique.
Mine fire is one of the severest accidents of coal mine in China. In the past few years, with the continuos
improvement of coal mine mechanization level, specially, with the widespread application and dissemination of
the fully mechanized caving method in China, new tasks based on traditional technique of fire fighting are
proposed. According to the practice of fire fighting in Chinese coal mine, Chongqing Branch and Fuxun
Branch of China Coal Research Institute（ CCRI） , have researched and developed fire fighting technology
and equipment which fit for Chinese coal mine, and devoted much more to the safety of production in Chinese
coal mines.
1. EVALUATING METHOD ON COAL SEAM SPONTANEOUS COMBUSTION TENDENCY
Before the design of a coal mine or the arrangement of the mining area or a coal face, mastering the
spontaneous combustion dangerous of the mining coal seam is the main basis for the designs of coal-mining
method and fire fighting system. The evaluating method on coal seam spontaneous combustion dangerous
includes mainly coal seam spontaneous combustion tendency grade and spontaneous combustion period. The
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appraisal methods of coal spontaneous combustion tendency grade can be classified into kindling temperature
method and chromatographic dynamic oxygen adsorbed method.
1
Chongqing Branch, CCRI, Shangqiao, Chongqing, 400037, China
The kindling temperature method is the most frequently used method in coal spontaneous combustion tendency
appraisal. According to the followed investigation to coal spontaneous combustion tendency and fire fact in one
hundred coal mines of China, the errors caused by this method are about twenty percent to thirty percent.
Among these errors, the errors between the appraisal result and the fire fact of hard coal and high ash coal are
mainly large. Seeing that the kindling temperature method can’t reflect the relationship between coal’s
adsorbing oxygen and oxidizing process and coal’s adsorbing oxygen property after the coal is cut down,
Fushun Branch, CCRI has studied chromatographic dynamic oxygen adsorbed method and its corresponding
instrument. The instrument is Model ZRJ-1 Coal Spontaneous Combustion Tendency Detection Instrument.
This method is based on the hypothesis that the property of coal’s adsorbing oxygen belongs to
mono-molecular film physical adsorption. In this method, by means of determining the area of the
chromatographic hump caused in the process that the coal adsorbs and desorbs oxygen, then adopting Longer
mono-molecular adsorption equation to calculate the quantity of coal’s adsorbing oxygen, or determining the
process carve of coal’s adsorbing oxygen, finally, the velocity of coal’s adsorbing oxygen can be worked out.
According to the quantity of coal’s adsorbing oxygen, the coals can be classified into three kinds: extreme easy
spontaneous combustion coal, spontaneous combustion coal and no spontaneous combustion tendency coal.
For the quantity of hard coal’s adsorbing oxygen is larger, it is much tally with the facts to determine the
spontaneous combustion tendency of hard coal, according to its oxygen adsorbed velocity.
Coal spontaneous combustion period means the necessary time that the coal reaches fire temperature under a
certain condition of supplying oxygen and collecting heat after the coal seam is exposed in the air because of
coal winning work. The shortest coal spontaneous combustion period means the necessary time that the coal
reaches fire temperature under the best condition of supplying oxygen and collecting heat after the coal seam is
exposed in the air because of coal winning work. The method to determine the shortest coal seam spontaneous
combustion period includes two kinds: one is statistical method, the other is experimental method. During “the
eighth five- year- scheme”, Fushun Branch, CCRI has researched the method to determine the shortest coal
seam spontaneous combustion period by means of Piled Coal Experimental Equipment, In this method, 50Kg
coal sample is put into Piled Coal Experiment Equipment, computer is used to control the ambient temperature,
and determine the velocity that the coal sample raises it’s temperature by means of following it each level,
according to the determined data of each point temperature in the piled coal , through a certain mathematics
model, the shortest coal spontaneous combustion period can be worked out. Tested and verified by experiments
in coal mine workshops, the errors of this result are bellow twenty percent. During “the eighth five-year
-scheme”, Chongqing Branch, CCRI has researched one method that the oxygen adsorbed velocity and the
surface oxidization heat of coal are regarded as the basic parameters to work out the shortest coal spontaneous
combustion period by means of heat balance mathematics model. In this method, determining the oxygen
adsorbed velocity of coal and working out the adsorbing heat by means of chromatographic dynamic oxygen
adsorbed method, determining coal’s surface oxidization heat by DSC method then the experimental shortest
spontaneous combustion period can be worked out by means of heat balance equation according to fact that
coal’s adsorption heat and oxidization heat are absorbed to raise coal’s temperature, to evaporate water in coal
and to desorb gas under an approximate heat insulated condition. The data worked out through the experiments
should be corrected by twelve kinds of correction coefficients including geology mining ventilation and so on ,
then the shortest spontaneous combustion period can by obtained. Tested and verified by experiments in coal
mine workshops, the errors of this result are between fourteen percent and twenty-five percent.
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The coal’s shortest spontaneous combustion period is the most important parameter to determine the safe coal
wining velocity of a spontaneous combustion coal seam. To ensure coal winning safety in spontaneous
combustion coal seam, the product of coal winning velocity of coal face and the shortest coal spontaneous
combustion period should be generally larger than the sum of the width of gob ventilation radiating belt and the
width of possible spontaneous combustion belt.
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2. FORECAST TECHNIQUE OF COAL SPONTANEOUS COMBUSTION
Collecting air samples from coal face, return air , coal face upper corner, gob, air stopping and so on artificially,
and analyzing the spontaneous combustion marker gas on ground by means of Gaseous-Phase Chromatographic
Instrument and Infrared Analytical Instrument, is the forecast method that used widely in Chinese coal mines.
Monitoring fire parameters of coal face and coal face upper corner by means of coal mine environmental
monitoring system has a certain directive function for safe product, too. In the past few years, tube bundle
mine fire monitoring system is widely used in Chinese coal mines, and has played an important role in
forecasting coal mine spontaneous combustion. Beam tube bundle monitoring system can forecast coal
spontaneous combustion. In this method, air sample from underground air sample collected point is pumped to
mode air collected control station underground through tube bundle made up of plastic tube, air samples from
each route are analyzed, and the data are managed by computer , then coal spontaneous combustion can be
forecasted according to the changes of the parameters . This system can monitor fire parameters of gob and
return air continuously , can also raise the accuracy rate of forecast greatly. At present , there are two kinds of
tube bundle monitoring systems used widely in Chinese coal mine: normal type and flameproof type, among
which the major products include Model KHY-1, Model KHY-2 and Model KHY which are manufactured by
Chongqing Branch, CCRI, and Model ASZ-II, Model KJF-1 which are manufactured by Fushun Branch, CCRI.
These products are used to monitor parameters including CO, CO2 , O2 , H2 , CH2 , C2 H2 , C2 H4 , C2 H6 and so on .
3. TECHNIQUE OF DETECTING HIDDEN FIRE SOURCE LOCATION IN GOB
Detecting hidden fire source location in gob accurately and effectively is a difficult technology problem all over
the world, each chief coal produced country has carried on a lot of researches, but no breakthrough at this
problem has been made so far. Gob hidden fire source can be classified into two categories: early fire source
and scope fire source. The chief method to detect fire source location in Chinese coal mines is measuring
temperature through borehole and analyzing the collected air sample. However, in this method, the engineering
amount of boreholes is very large and a large amount of time and work would be taken. In the past few years,
according to the defect of traditional detecting method, several methods to detect mine fire source location have
been tried early or late in gobs of Chinese coal mines: temperature monitor buried method, geologic radar
method and radon measurement method. During “ the eighth five-year-scheme” , Chongqing Branch, CCRI has
succeeded in researching Model KHT8500 Mine Gob Fire Source Location Monitoring System. This system is
made up of temperature detectors and receiver station. The temperature detector with a certain code is buried in
gob in advance. While its detected temperature reaches alarm point, the detector transmits a electromagnetic
wave signal with the same code as that of itself, according to the code information received by the receiver
station, the gob early fire source location can be determined. This system has been tested in Beijiao Coalmine,
Furong Mining Bureau, and has succeeded in detecting early fire source location. In this method a lot of
detectors must be buried in advance, then high cost is an obstacle that restricts the wide-ranging use of this
technique.
Chongqing Branch, CCRI has carried on some useful attempts at detecting gob scope source by means of
geologic radar, which has produced a certain effect. This method is based on electromagnetic wave reflected
principle: high frequency electromagnetic wave will produce object reflected wave when it meets the different
electric conductivity interface of different medium. This different electric conductivity means that the electric
conductivity and the dielectric constant of the mediums of two sides of interface is different. In scope fire
district, the coal and rock will take place physical changes and chemical changes under high temperature. Their
relative dielectric constant and electric conductivity become different from that of the coal and rock around
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them, which forms a interface of clear difference of electric conductivity, therefore, radar reflected waves can
be received well. According to the reflected waves, the scope fire source location can be detected accurately.
This technique has been applied in Lingbei Coal Mine of Hegang Mining Bureau and Dongtan Coal Mine of
Yanzhou Mining Bureau. About this technique, to enlarge the detected distance and improve the accuracy rate
is key technique that should be gone further into.
Isotope ground radon measurement method that is applied in detecting mine scope fire source location has been
researched successfully early in 1990s by Shanxi Mining College. As we know well, radon is a kind of mother
nuclein. It exists widely in soil, rock and coal measure stratum. It is a natural phenomenon that radon emits to
atmosphere from the earth’s crust. The emission of the radon is closely related with temperature. By means of
detecting the difference between the normal area and the abnormal area where radon emits, the location and the
range of mine fire district can be determined. Radon daughter is taken for the detected object to detect radon’s
abnormality outdoors. The applications in Xuangang Mining Bureau, Luan Mining Bureau Gujiao Mining
Bureau and Datong Mining Bureau indicate that this technique is practicable and its precision is high.
4. TECHNIQUE AND EQUIPMENT OF SPONTANEOUS COMBUSTION PREVENTION AND
CONTROL
“Two lines, two belts and two roadways” of coal face are important position to prevent and control
spontaneous combustion. Along with fully mechanized caving method being spread and applied widely in
China, spontaneous combustion of gate road becomes frequent increasingly. According to different mining
technique condition, relevant fire fighting systems have been founded in coal mine of China. In blast winning
faces and conventionally mechanized coal winning faces, comprehensive fire fighting technique that sludge
grouting is main part that combined with air pressure balance ventilation, preventing leakage by stopping
retarder is applied normally. In high-yield and efficient fully mechanized coal winning faces, comprehensive
fire fighting technique that nitrogen injection is main part which combined with making stopping speedily air
pressure balance ventilation speed coagulant or gelatinizer retarder is applied normally.
In the past few yews gelatinnizer fire fighting technique has been applied widely in Yanzhou Mining Bureau
Tongchuan mining bureau Pingdingshan mining bureau Yangquan mining Bureau and so on. The compositions
of gelatinizer are: (NH4 )HCO3 , （NH4 ）2 SO4 , sodium silicate additive and water. These compositions form gluey
matter after being mixed and reacting. Among these compositions the proportion of water in volume is above
85% and it can reach 95%. The time to form the gelatinizer can be regulated by means of changing the
proportion of its compositions. The gelatinizer is transported to wall fracture gob or gate in order to prevent
leakage and cool to extinguish.
To fit in with the needs of mine underground extinguish grouting, leakage preventing and stopping
constructing, Chongqing Branch, CCRI has developed successfully, Model KBJ-100/6 Underground
Movable Grouting Pump, during “ the eighth five-year-scheme”. Its working pressure is 6Mpa, its
flow is 100L/min, its transported distance is 800m. Fushun Branch, CCRI has developed Model ZY-340
Mine Grouting Pump. Its working pressure is 2.4MPa, its flow is 8m 3 /h. These installations have played an
important role in coal mine fire fighting.
“Coal mine safety rules” that is being used at present in China provides that comprehensive fire preventive
measures mainly relying on inert gas injecting must be applied when thick seam or very thick seam with
spontaneous combustion tendency is being mined by means of fully mechanized coal inning method. It is
nitrogen that is used to in fire extinguish by inert gas. As one of key technologies of fire prevention with
nitrogen, nitrogen injection technique should be determined according to the concrete conditions of production.
During the past ten years, large progress has been made in mine nitrogen produce equipment in China.
According to nitrogen produced method, present nitrogen injection equipment made in China, can be classified
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into three kinds: adsorbing by changing pressure, separating by membrane method and separating from air by
deep cooling method their moved ways can be classified into three kinds: under ground movable way, ground
movable way and ground fixed way. Chongqing branch, CCRI combined with certain units has developed three
models of nitrogen produced machine by applying carbon molecule sifter changing pressure adsorption
technology. These three models are Model BZND-500 Ground Movable Nitrogen Produced Machine (nitrogen
Produced velocity is 500m 3 /h, nitrogen purity is 97%), Model KYZD-800 Ground Movable Nitrogen Produced
Machine( nitrogen produced velocity is 800m 3 /h, nitrogen purity is 97% ), and Model JXZD-400 Underground
Movable Nitrogen Produced Machine(nitrogen produced velocity is 400m 3 /h, nitrogen purity is 97%). Applying
middle empty membrane separated method; Fushun branch, CCRI has developed Model MD-350 Underground
Movable Nitrogen Produced Equipment（nitrogen produced velocity is 350m 3 /h, nitrogen purity is 97% ）. All
these installations are used widely in Xishan Mining Bureau, Huating Mining Bureau, Huaibei, Mining Bureau.
Yanzhou Mining Bureau, Yangquan Mining Bureau and so on.
To the fully mechanized caving face, its mining intensity and mining coal space are large. Now, the productive
output of the device of nitrogen produce in china is relative small, so the device can not meet completely the
need of the fire control on the full mechanized caving face. The development of the device of nitrogen produce
with big flow (the nitrogen produce velocity is 800~1500m 3 ∕h) is the developing direction of the mine
nitrogen produce device in the few years.
5. EXTERNAL FIRE FIGHTING TECHNOLOGY
Among the external fires of Chinese coal mine, underground conveyer belt fire is the largest proportion and its
loss is the most serious. Slide friction between conveyer belt and main roller produces head, and increases the
temperature of conveyer belt, then causes fire. Fire can be also caused by underground electric welding, electric
cables short circuit, electric equipment breakdown, supporting roller blocked and so on. In the past ten years,
conveyer belt fire fighting equipment that have been developed in China can be classified into two kinds:
electrical way equipment and mechanical way equipment. The main products are Model KHJ-1, Model KNH-1.
The detected fire parameters are temperature, smog, velocity, ultraviolet light, infrared ray, CO, CO2 , H2 S, and
so on. Electric fire fighting system has very powerful function to detect, to give an alarm, to stop power, to
prevent fire, and so on. Its main fire fighting mediums are water foam and fire fighting powder. The technique
to detect conveyer belt fire location in a long distance is a technical barrier. During “the ninth five-year
-scheme”, to fit the need to prevent conveyer belt fire, fibre-optic laser, radar and semiconductor heat sensitive
location systems are being developed in China.
Spreading and applying flame retarded belt in coal mines is an important measure to prevent conveyer belt fire.
The mechanical performance and safety performance of coal mine flame retarded belts used widely in China
are inferior to that of external similar products. Developing flame retarded belt with high performance is an
important task facing us. Moreover during belts being used, they are in the situation being rubbed and worn
continuously, and their flame retarded performance and static electricity resisted performance may be decrease.
Then, during flame retarded belts are used in coal mines, the safety performance of coal mine belts should be
examined regularly, and the belts that aren’t up to the safety standard should not be used underground in coal
mine.
Belt fire takes place and develops speedily. Fire will produce high temperature air current, smog and CO, which
will do grievous harm to the life safety of underground personnel. For this reason, Datun Coal-Electric Bower
Company and Kailuan Mining Bureau have developed belt fire air current controlled system. When a fire
occurs, fire air current is draw into return air current by opening far distance automatic air door in order to
avoid that the disaster air current would do harm to the working personnel at coal face.
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Setting up fire-proof door at pit bottom, main roadway, chamber and so on is the most important measure to
prevent the spread of external fire flame smog and poisonous air. At present, underground fire proof doors are
mainly controlled artificially. However, as soon as external fire occurs, underground personnel become panicstricken and eager to seek asylum, or the fire-proof door is so far that underground personnel cant arrive and
close it . Therefore, setting up fire-proof door automatic controlled equipment can ensure that the fire-proof door
can be closed automatically in time. Chongqing Branch, CCRI has developed model FHM-1 Mine Nonpower
Air-Proof Door Automatically Controlled Equipment. It applies mechanical structure. Its started temperature is
43℃, 56℃, or 68℃ separately. It can ensure that the air-proof door can be closed automatically in time at the
initial stage of fire.
Fuxun Branch, CCRI has developed Inert Gas Produced Equipment (Model DQ-150, Model DQ-500 and
Model DQ-1000). Model BGP-200 Electric Foam Produced Machine, Model YZWP-180 Inert Gas Foam
Produced Equipment and so on. These installations have been equipped in the coal mine rescue teams of many
Mining Bureaus to put out roadway fire and room fire. When the equipment of DQ series works, their internal
combustion engines burn fuel to rid the oxygen of air. The remained gas is injected into fire district after it is
cooled to put out fire by suffocation. Their gas produced velocities are150m 3 /h ,500m 3 /h and 1000m 3 /h
separately. The compositions of the produced inert gas are N2 , CO2 , and vapour. Model BGP Electric Foam
Produced Machine produces foam by mechanical way. Its foaming multiple is about 600 to 800 times normally.
The isolated and cooled function of foam can put out fire.
6.CONCLUSION
After many years' efforts of mine technical personnel and scientific workers, fire prevention and control systems
that suit the characteristics of Chinese coal mines. However, we should also recognize that fire accidents take
place sometimes in coal mines of China. It is demanded that we should research continuously the technical
problems arisen in production practice, strengthen technical development and spread, ensure capital investment
in fire fighting, raise the management level continually and ensure the safety production in China.
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