Arch. Min. Sci., Vol. 55 (2010), No 3, p. 547–560

Arch. Min. Sci., Vol. 55 (2010), No 3, p. 547–560

Arch. Min. Sci., Vol. 55 (2010), No 3, p. 547–560
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Electronic version (in color) of this paper is available: http://mining.archives.pl
MIROSŁAW WIERZBICKI*, BARBARA DUTKA*
THE INFLUENCE OF TEMPERATURE CHANGES OF THE STRUCTURALLY DEFORMED
COAL–METHANE SYSTEM ON THE TOTAL METHANE CONTENT
WPŁYW ZMIAN TEMPERATURY UKŁADU WĘGIEL-METAN NA GAZOPOJEMNOŚĆ WĘGLA
ODMIENIONEGO STRUKTURALNIE
Tectonic deformations in hard coal seams may be related with structurally deformed and altered coal
zones (so-called sheared zones). The example of such coal structure is shown in fig. 1 and 2. The physicochemical properties of the above mentioned coal influences the local increase of methane and outburst risk
in hard coal mines. One of the most important parameters in the coal-methane system, which determines
the methane sorption ability in coal seams, is the sorption capacity of coal. A change in temperature leads
to a sorption equilibrium disturbance and to a change of the sorption capacity.
This article presents the results of the sorption studies concerning the structurally deformed coal
sampled from a methane and outburst prone zone. The sorption measurements were carried out by means
of the volumetric equilibrium method. The sorption isotherms of methane were determined (fig. 4) at the
temperature range of 298-318K and for pressures up to 1.5 MPa. The studies revealed that a temperature
increase reduces the methane sorption ability of structurally deformed coal.
To the experimental points, obtained from the sorption measurements, the Langmuir isotherm equations were fitted. Tab. 1 compares the am and b parameters which were determined for each of the five
concerned temperatures and also tabulates the values of the so-called Langmuir pressures PL which equal
to the reverse of the Langmuir constant b. This paper presents the temperature correlations of the am and
the b constants. They are of linear character, as it may be seen in fig. 6 and 7. The functional correlations
between the methane sorption capacity, temperature and pressure were examined – the equations (4) and
(5). These correlations may become a contribution to the methane balance basing on the knowledge of the
methane content of the coal seam and the sorption capacity of coal and recreation of the in situ conditions
on the basis of the measurements in laboratory conditions. Additionally, fig. 8 presents the methane sorption capacity as a function of pressure and temperature, what was shown as a surface chart. The equation
(6) may be useful to determine the methane equilibrium pressure p which corresponds to the determined
sorption capacity of coal a at any T temperature. The amount of free gas in coal may be determined using
the equation (7), assuming the coal porosity is known. The percentage volume fraction of the free methane
in the total methane content was compared assuming the porosity of coal was typical for undisturbed
(structurally unchanged) coal (6%) and the porosity of structurally deformed coal (24.5%). This matter
was examined in reference to the temperature influence. The results were shown in fig. 9.
Keywords: Structurally deformed coal, sorption, total methane content, coal and gas outburst
*
STRATA MECHANICS RESEARCH INSTITUTE OF THE POLISH ACADEMY OF SCIENCES, 27, REYMONTA STR., 30-059
KRAKOW, POLAND
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Obecność deformacji tektonicznych w pokładach węglowych może wiązać się z występowaniem stref
węgla o strukturze zniszczonej i odmienionej. Przykład struktury wewnętrznej badanego węgla pokazano
na rysunkach 1 i 2. Cechy fizykochemiczne tego typu węgli wpływają na lokalny wzrost zagrożenia
metanowego i wyrzutowego w kopalniach węgla kamiennego.
Jednym z podstawowych parametrów w układzie węgiel-gaz, decydującym o możliwości akumulacji
metanu w pokładach węgla kamiennego jest pojemność sorpcyjna węgla. Zmiana temperatury układu
pociąga za sobą zaburzenie istniejącej równowagi sorpcyjnej i zmianę pojemności sorpcyjnej.
W niniejszej pracy omówiono wyniki badań sorpcyjnych przeprowadzonych na węglu odmienionym
strukturalnie, pobranym z rejonu szczególnego zagrożenia wyrzutowego i metanowego. Badania prowadzono metodą objętościową równowagową. Wykonano izotermy sorpcji metanu w zakresie temperatur od
298 do 318K dla ciśnień równowagowych do ok. 1,5 MPa – rysunek 4. Wykazano, iż wzrost temperatury
ogranicza zdolności sorpcyjne węgla odmienionego względem metanu.
Do punktów doświadczalnych uzyskanych z pomiarów sorpcyjnych dopasowano równania izoterm
Langmuira. W tabeli 1 zestawiono parametry am i b wyznaczone dla każdej z rozpatrywanych temperatur oraz wartości tzw. ciśnień Langmuira PL będących odwrotnością stałej Langmuira b. Przedstawiono
temperaturowe zależności stałych am oraz b. Mają one charakter liniowy, co widoczne jest na rysunkach
6 i 7. Przeanalizowano zależności funkcyjne pomiędzy pojemnością sorpcyjną, temperaturą i ciśnieniem
– równania (4) oraz (5). Podane zależności mogą być przyczynkiem do bilansowania metanu na podstawie
znajomości metanonośności i pojemności sorpcyjnej oraz przełożenia wyników pomiarów w temperaturze
laboratoryjnej na warunki in situ. Dodatkowo, na rysunku 8, zależność pojemności sorpcyjnej w funkcji
ciśnienia i temperatury przedstawiono w postaci wykresu powierzchniowego. Na podstawie równania (6)
można wyliczyć ciśnienie równowagowe p metanu, odpowiadające określonej pojemności sorpcyjnej a
węgla w znanej temperaturze T, a następnie na podstawie równania (7) zawartość gazu wolnego w węglu
(przy znanej jego porowatości). Porównano procentowe udziały objętościowe metanu wolnego w całkowitej
jego zawartości w węglu, przyjmując porowatość węgla typową dla węgli nieodmienionych strukturalnie
(6%) oraz porowatość węgla o strukturze odmienionej (24,5%). Zagadnienie przeanalizowano pod kątem
wpływu temperatury. Wyniki przedstawiono na rysunku 9.
Słowa kluczowe: Węgiel odmieniony strukturalnie, sorpcja, gazopojemność węgla, wyrzut węgla i gazu
1. Introduction
Methane is inseparable from the underground mining in the hard coal seams of the southwest part of the Upper Silesian Coal Basin. The amount of methane abundant in a coal seam is
determined by a few factors such as: the coal rank, the maceral composition of coal, its specific
surface area and the moisture content. Moreover, the type and permeability of overburden rocks
also determine the amount of methane present. Information concerned the mathematical models of
the methane outflow from the rock media, which take account of sorption processes was discussed
by Siemek J. et al., 1990. The presence of tectonic disturbances (in particular the disturbances of
a discontinuous character) may have at least a dual aspect. On the one hand, disturbances such
as faults may become a way of easier gas migration from deeper areas, and on the other hand,
the structurally deformed coal may occur in the areas close to a fault fissure. The structurally
deformed coal of a weakened mechanical strength and intensified porosity raise the local methane
and outburst risk, which is referred to by scholars among others: Lama R.D. and Bodziony J.,
1996; Li H. et al., 2003; Cao Y. et al., 2001 and Atkins A.S. et al., 2008. The issue of the influence
of coal structural changes on methane and coal and methane outburst risk was also raised by the
following Polish scholars: Cybulski W. and Piskorska-Kalisz Z., 1959; Bodziony J. et al., 1990.
This paper presents the sorption studies results, carried out at different temperature conditions for structurally deformed coal, which was sampled from the section D of „Zofiówka” Coal
Mine. It is a continuation of research concerning coal of an altered structure. The aim of this
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work is a more accurate determination of structurally deformed coal properties. The structural
properties and certain properties of surface morphology of this material were described in the
papers of: Wierzbicki M. and Młynarczuk M., 2006; Młynarczuk M. and Wierzbicki M., 2009;
Jakubów A. et al., 2006. Methane risk and rocks and methane outburst risk, resulting from the
presence of that type of structures in coal seams were referred to in the articles of among others:
Tor A. et al., 2007.
The authors focus on the properties of the structurally deformed coal as a methane capacitor,
considering the temperature changes of the coal-methane system. The gas, contained in a specific
mass (or volume) of coal, may be identified as two types of gas namely the sorbed gas and the
free gas. The first is connected with the inner surface. The latter is present in pores and fractures
of coal. As for the methane and outburst risk, it is crucial to determine the total methane content
of coal, but also the free methane volume fraction in the total methane content of coal. Free
methane may be a trigger for a sudden methane release, and accumulated under a higher pressure than the atmospheric pressure may become the main source of potential energy, which may
lead to a coal structure destruction and outburst occurrence. It is assumed that the sorbed gas is
mainly responsible for moving the outburst masses (Topolnicki, 1999).
This paper introduces certain aspects of gas balance for structurally deformed coal, the relations between free methane and sorbed methane and as well the influence of temperature on the
methane accumulation ability of coal. The results of the studies can be applied to determine the total methane content of the structurally altered coal – from an outburst and methane prone zone.
The knowledge of the temperature influence on the sorption capacity of coal may be also
useful in describing processes in the coal-gas system, in the areas where the temperature gradient
occurs, for instance in the immediate vicinity of mining excavations, or in the seam areas covered
with self-igniting coal or underground fires.
2. Characteristics of structurally deformed coal
The studies concern the coal sampled from the fault area of the gate road D-8, coal seam
409/4 in the Zofiówka Coal Mine (Jastrzębie Zdrój, Poland). During the mining process of this
excavation, an area of fault zone was encountered with a fault throw of h = 1.6÷2.1 m and with
a fault planes’ inclination of 87º/E. The area of a width of about 2.0÷2.5 m was filled with vitreous mudstone and inserts of sandstone. A vitreous coal plane with horizontal grooves emerged
behind the fault, proving that the fault plane has slipped. At the contact area with the fault plane,
coal of deformed structure of a thickness of about 0.40 m occurred. More detailed information
concerning the place of sampling and geological-mining conditions in the section D of the coal
seam 409/4 can be acquired in the articles of: Tor A. et al., 2007.
The example of structurally deformed coal is shown in the image obtained from an optical
microscope – fig. 1 and from a scanning microscope – fig. 2. Structural properties of the examined
coal were, undoubtedly, the cause of a raised methane level as well as the risk of coal and methane
outburst in the gate road D-8, by approaching the fault (Wierzbicki & Młynarczuk, 2006).
The examined coal occurred in the fault area of the same geological disturbance, which was
the cause of the coal and methane outburst in the coal seam 409/4 on 22 November 2005. The
structure of deformed coal is very similar to the structure of the coal sampled from the outburst
area described in the paper (Młynarczuk & Wierzbicki, 2009) and is marked by a numerous net-
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Fig. 1. Structurally deformed coal – the image from optical microscope. Enlargement 200×
Fig. 2. The SEM image of structurally deformed coal. Enlargement 12000×
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work of inner fractures. The porosity ε of the examined coal was determined on the base of the
real density measured by the helium method (ρs = 1.386 g/cm3) and the apparent density obtained
from the quasi-fluid pycnometry (ρp = 1.046 g/cm3 ). The density measurements were carried out
by using the AccuPyc and GeoPyc pycnometers produced by Micromeritics. The mean porosity
of structurally deformed coal was ε = 24.5%. Apart from the intensified porosity, the examined
coal has also some mechanical properties which are significantly different from the typical coal
from the coal seam 409/4. The mean firmness coefficient (Protodiakonov strength) in the coal
seam remained at the level of 0.3÷0.4. For the sample of structurally deformed coal the firmness
coefficient had a very low value f = 0.09, which is distinctive for very weak coals. The proximate
analysis of the examined coal material was carried out. The volatile matter content amounted to
V daf = 24.6% (wg PN-ISO 562), the ash content was A a = 4.7% (wg PN-ISO 1171) and the total
moisture content of coal was Wt = 1.2% (wg PN-80 G-04511).
3. Sorption studies
The sorption measurements were carried out using the equilibrium volumetric method. This
method enables to determine the sorbed amount of methane, when the coal-methane system is
in the state of equilibrium. The experimental setup is schematically shown in fig. 3. It consists
of two chambers connected with a valve. One of the chambers is a gas chamber and the second
one is a sample chamber. The gas chamber is connected with a methane bottle and manometer.
The sample chamber contains a given amount of a coal sample. Isothermic conditions were
provided by a water bath at a constant temperature. The temperature was maintained with an accuracy of ±0.1°C. The pressure was controlled with a pressure transducer connected with a data
acquisition system.
Fig. 3. Schematic diagram of the experimental setup
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The sorption studies were carried out on a coal sample of a 0.5÷1.0 mm grain fraction,
previously dried off at 80°C. About 50 g of the sample was placed in the sample chamber and
outgassed at a raised temperature until the vacuum reached at least the value of 5 ·10–3 hPa. After
injection of a known volume of methane to the gas chamber and after stabilization of pressure
and temperature, the sorption measurement was triggered by the opening of the valve connecting both chambers. A pressure drop was being recorded until the final equilibrium pressure was
reached.
Five sorption isotherms of methane were determined at the temperature range of 298÷318K
(from 25 to 45°C) for equilibrium pressures up to 1.5 MPa. For the determination of one point
for each of the five isotherms, one dose of methane was given.
The following procedure was applied:
1. dosing of a known volume of methane to the gas chamber at 298K,
2. waiting for pressure and temperature stabilization,
3. beginning of sorption measurement by opening of the valve connecting both chambers,
4. waiting for pressure stabilization (reaching of the equilibrium pressure for a given point
of the isotherm),
5. calculation of the amount of the sorbed methane on the basis of the gas balance of the
system,
6. temperature raising of 5K,
7. waiting for another reaching of sorption equilibrium,
8. calculation of the amount of the sorbed methane considering the temperature change,
9. another temperature raising of 5K.
After determination of the sorption capacity at the temperature of 318K, the temperature
of the system was being lowered to 298K, and another dose of methane was added. Thus, the
next cycle began. The sorption was carried out to obtain isotherm points within the intended
equilibrium pressure range.
4. Methane sorption isotherms at different temperatures
For the sorbent-sorbate system (in this case coal-methane system) the sorption capacity a
depends on the temperature T and gas pressure p (pressure of a free gas):
a = f ( p, T )
Fig. 4 shows the obtained sorption isotherms of methane, determined for the examined coal
at different temperatures, calculated for a dry and ash free coal state. The examined coal is a
good methane sorbent. As fig. 4 shows, the layout of the isotherms indicates that an increase in
temperature leads to a drop of the sorption capacity of coal. For instance, the temperature increase
from 298K to 313K, at the equilibrium pressure of 1 MPa, results in a drop of the sorption capacity of about Δa = 2 cm3/g, that is about 20%. Fig. 5 presents the drop of the sorbed methane’s
level triggered by a temperature increase of the system from 298K to 313K as a function of the
(a - a 313 )
equilibrium pressure: r = 100 298
.
a 298
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14
25ºC (298K)
30ºC (303K)
35ºC (308K)
40ºC (313K)
45ºC (318K)
12
a, cm 3/g
10
8
6
4
2
0
0
0.4
0.8
p, MPa
1.2
1.6
2
Fig. 4. Methane sorption equilibrium points for the studied coal together
with fitted Langmuir isotherm equations for temperature range 298÷318K
28
r = Da, %
24
20
16
12
0
0.4
0.8
p, MPa
1.2
1.6
2
Fig. 5. The change of sorption capacity due to an increase in temperature of the coal-methane system
from 298K to 313K
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The largest reduction of the sorption capacity was observed for the lower equilibrium
pressure range and at the pressure p → ∞, at the studied temperature range it is ca. 27%. At
equilibrium pressure of 1.6 MPa, the loss in sorption capacity of coal is about 14% of sorption
quantity at 298K.
The phenomenon of the coal’s ability to lower the sorption with a temperature increase was
observed by many researchers among others: Levy J.H. et al., 1997; Nodzeński A. and Hołda S.,
2001 and Bustin R.M. and Clarkson C.R., 1998.
The Langmuir isotherm equation (1) was fitted to the experimental data for each of the five
isotherms:
a = am bp /(1 + bp)
where:
a —
am —
b —
p —
(1)
sorbed amount of methane at the equilibrium pressure p, cm3/g
maximum sorption capacity at p → ∞ (saturation state), cm3/g
constant characteristic for the coal-methane system, MPa–1
free gas pressure, MPa.
Equation (1) contains the am constant, which is a value of the maximum sorption capacity,
whereas the b constant is a reverse of the so-called Langmuir pressure PL, at which the surface
coverage of a sample equals 0.5am. Within the temperature range of 298÷318K, the examined
coal may accumulate maximally 17.5 and 15.6 cm3/g, respectively, and a half of the maximum
sorption capacity is reached at the pressure range of 0.58÷0.80 MPa.
The values of the Langmuir equation parameters for individual temperatures are compared
in Tab. 1.
TABLE 1
Langmuir isotherm equation parameters at different temperatures: am and b constants
and PL parameter calculated on the basis of b constant
T, K
298
303
308
313
318
am, cm3/g
17.5
17.0
16.6
16.1
15.6
b, MPa–1
1.73
1.60
1.47
1.36
1.26
PL, MPa
0.58
0.62
0.68
0.73
0.80
The correlations between the Langmuir equation constants and the temperature are shown
in fig. 6 and 7. They are of linear character:
a = –0.094T + 45.512
(2)
b = –0.0236T + 8.753
(3)
A temperature increase of the sorbent-sorbate system of 1K caused a drop of the maximum
sorption capacity of the structurally deformed coal towards the methane of ca. 0.095 cm3/g what
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17.8
1.8
17.2
b, PMa –1
am, cm 3/g
1.6
16.6
1.4
16
15.4
296
300
304
308
T, K
312
316
1.2
320
Fig. 6. am constant from Langmuir equation (1)
vs. temperature
296
300
304
308
T, K
312
316
320
Fig. 7. b constant from Langmuir equation (1)
vs. temperature
also simultaneously caused a Langmuir pressure increase of ca. 0.011 MPa.
The sorption equation takes the form of:
a ( p, T ) = am (T )
b (T ) p
1 + b (T ) p
(4)
and after the substitution of the linear equations (2) and (3), for pressures in MPa units and for
temperatures in Kelwins, may be written as the following correlation:
a ( p, T ) =
(0.002218T 2 - 1.897 T + 398.367 ) p
1 - (0.0236T - 8.753) p
(5)
Obtained correlation allows to calculate the sorption capacity of studied coal at any pressure
value and temperature from the ranges of 0÷1.5 MPa and 298÷318K, respectively. a(p,T) relation was presented in the form of isolines, what was shown in fig. 8.
On the base of the equation (5), methane equilibrium pressure p, which corresponds to the
specific sorption capacity of coal a at a known temperature T, may be calculated as:
p (a,T ) =
a
(0.0236 aT - 8.753 a + 0.0022 T 2 - 1.89T + 398.367 )
(6)
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Fig. 8. Surface chart a(p,T ) for the studied coal
5. The total gas content of structurally deformed coal
The methane equilibrium pressure p and coal porosity ε are necessary to calculate the free
methane content in coal, falling to a mass unit. According to the STP conditions, the volume of
a free gas can be calculated from the following formula:
w( p, T ) =
where:
w
ε
p
p0
T
ρ
—
—
—
—
—
—
e p 298
×
r p0 T
(7)
volume of free methane, cm3/g
porosity, –
pressure of free methane, MPa
atmospheric pressure, MPa
temperature, K
density of coal, g/cm3.
Fig. 9 presents the percentage volume fraction of free methane in the total methane contained
in coal, for selected temperatures of the sorption measurements. As it may be seen from the graph,
a temperature increase in the examined range of pressures is accompanied by an increase of the
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free methane volume fraction in the total gas contained in coal. This volume fraction, at the
1.6 MPa equilibrium pressure, amounts to about 22.7% for 298K and about 24.6% for 313K. It
must be mentioned that the volume fraction is strongly correlated with the porosity of coal, which
is, in this case, very high and was determined as ε = 24.5%. It is worth to notice, that according
to the equation (7), the free gas content in coal for isobaric-isothermic conditions is determined
e
by the equation: w (e ) = A
, where A represents the constant.
1- e
30
Free methane volume fraction, %
e = 24.5% (313K)
e = 24.5% (298K)
20
10
e = 6.0% (298K)
0
0
0.4
0.8
p, MPa
1.2
1.6
2
Fig. 9. Free methane volume fraction in the total methane contained in coal for selected temperatures
of coal-methane system and coal porosity of 6 and 24.5%
For visualizing the influence of coal porosity on the free methane volume fraction in the total
methane contained in coal, a square-marked line was used to show the value of this parameter,
providing that coal has the same sorption ability as it was deliberated in this paper, but is the
undisturbed coal of a 6% porosity (Czapliński A., 1994). Hence, an increase of porosity from 6%
to 24.5% results in a 500%-increase of the amount of gas contained in coal pores and fractures
for the same thermodynamic conditions.
The assessment of the amount of sorbed gas and gas contained in the coal pore space
(as a function of p and T) enabled us to reconstruct the total methane content in coal for specific
thermodynamic conditions, and to determine the volume fraction of free methane in the total
methane contained in coal.
The total methane content for structurally deformed coal as a function of equilibrium pressure for the temperature range under study is shown in fig. 10.
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20
298K
303K
308K
313K
318K
Total methane content, cm 3/g
16
12
8
4
0
0
0.4
0.8
p, MPa
1.2
1.6
2
Fig. 10. The total methane content of coal as a function of equilibrium pressure
for different temperatures
The total gas content of coal, at the equilibrium pressure of 1.6 MPa and at the temperatures
298 and 318K were (a + w)298 = 16.6 cm3/g and (a + w)318 = 13.9 cm3/g, respectively. In this way,
a temperature increase of coal-methane system of about 20K results in a total gas content reduction
of ca. 16%. The graphs given in fig. 10 may be useful to estimate the methane seam pressure, for
a known methane content of a coal bed. For the natural methane content of Mn = 8 m3/Mg, at the
temperature of coal bed of Tz = 313K (40°C) the equilibrium pressure amounts to 0.55 MPa, what
is a value close to the values of methane coal seam pressures obtained from direct measurements
described in the work of (Topolnicki J. et al., 2004). For a better insight into this matter, it is
necessary to know the humidity of coal and its influence on the sorption capacity of coal.
6. Conclusions
The sorption studies carried out in the structurally deformed coal-methane system at the
temperatures 298, 303, 308, 313 and 318K revealed that a temperature increase of the sorbentsorbate system leads to a significant decrease of the sorption capacity of coal. The highest relative
changes of the methane sorption capacity were observed at lower equilibrium pressures. It means
that with an equilibrium pressure increase, the sorption capacity of the structurally deformed
coal is less responsive to a temperature change. The methane sorption on the examined coal may
be described by means of the Langmuir isotherm equation. The temperature correlations of the
Langmuir isotherm constants (am or b) are of linear character.
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The presented measurements enabled the calculation of the methane sorption capacity for
different thermodynamic conditions at the equilibrium pressure range of 0÷1.5 MPa and for the
temperature range of 298÷318K. Basing on the above-mentioned studies, the methane sorbed and
free methane contents were determined as a function of the equilibrium pressure. The percentage
volume fraction of free methane in the total methane content of structurally deformed coal at the
temperatures 298K and 313K showed that a porosity increase from 6 to 24.5% results in a 500%
– increase of the free methane at the same thermodynamic conditions.
The correlation between the total methane content of coal and equilibrium pressure for different temperatures may be useful to estimate the methane seam pressure, for a known methane
content of a coal bed. For a better insight into this matter, it is necessary to know the humidity
of coal and its influence on the sorption capacity of coal.
The presented research work was supported by the Ministry of Science and Higher Education, Project No R09 027 02.
References
Atkins A.S., Singh R.N., Pathan A.G., 2008. Outburst risks in coal mining operations and application of social networks
in knowledge management systems, Arch. Min. Sci., vol. 53, No. 1, p. 31-52.
Bodziony J., Kraj W., Ratajczak T., 1990. Zastosowanie stereologii w badaniach struktury węgli dolnośląskich, w:
Górotwór jako ośrodek wielofazowy – wyrzuty skalno-gazowe (in Polish), red. J. Litwiniszyn, T. I, Wyd. AGH
Kraków.
Bustin R.M., Clarkson C.R., 1998. Geological controls on coalbed methane reservoir capacity and gas content, International Journal of Coal Geology, Vol. 38, 1-2, 3-26,
Cao Y., He D., Glick D.C., 2001. Coal and gas outbursts in footwalls of reverse faults, International Journal of Coal
Geology, 48, 47-63.
Cybulski W., Piskorska-Kalisz Z., 1959. Określenie mikroszczelinowatości węgla w pokładach zagrożonych wyrzutami
gazów i skał metodą optyczną oraz badanie wpływu strzelania na naturalną szczelinowatość węgla z pokładów,
Komunikat GIG, nr 456, 1959.
Czapliński A., 1994. Praca zbiorowa pod Redakcją A. Czaplińskiego, Węgiel kamienny, Wydawnictwo AGH, Kraków.
Jakubów A., Tor A., Wierzbicki M., 2006. Własności strukturalne węgla w rejonie wyrzutu węgla i gazu w chodniku
transportowym D-6 pokład 409/4 KWK „Zofiówka”, XIII Międzynarodowa Konferencja Naukowo-Techniczna
GZN 2006, 7-10.XI.2006, Ustroń.
Lama R.D., Bodziony J., 1996. Outbursts of gas, coal and rock in underground coal mines, R.D. Lama and Associates,
Wolongong NSW, Australia.
Levy J.H., Day S.J., Killingley J.S., 1997. Methane capacities of Bowen Basin coals related to coal properties, Fuel,
vol. 76, No. 9, 813-819.
Li H., Ogawa Y., Shimada S., 2003. Mechanism of methane flow through sheared coals and its role in methane recovery,
Fuel, 82, 1271-1279.
Młynarczuk M., Wierzbicki M., 2009. Stereological and profilometry methods in detection of structural deformations
in coal samples collected from the rock and outburst zone in the “Zofiówka” Colliery, Arch. Min. Sci., vol. 54,
No 2, p. 189-201.
Nodzeński A., Hołda S. 2001. Isosteric heats of methane sorption on hard coals of different ranks at elevated pressures,
Arch. Min. Sci., vol. 46, No 4, p. 481-490.
Topolnicki J. 1999. Wyrzuty skalno-gazowe w świetle badań laboratoryjnych i modelowych, Kraków, Wydawnictwo
IGSMiE.
560
Topolnicki J., Wierzbicki M., Skoczylas N. 2004. Wyrzuty skalno-gazowe w świetle badań laboratoryjnych i pomiarów
kopalnianych, Arch. Min. Sci., vol. 49, p. 99-116.
Tor A., Jakubów A., Wierzbicki M. 2007. Zagrożenie wyrzutem metanu i skał przy drążeniu wyrobisk korytarzowych
w pokładzie 409/4 partia D KWK „Zofiówka”, Prace Naukowe GIG Górnictwo i Środowisko, nr IV, 263-273.
Wierzbicki M., Młynarczuk M., 2006. Microscopic analysis of structure of coal samples collected after an gas and coal
outbursts in the gallery D-6 coal seam 409/4 in the „Zofiówka” coal mine (Upper Silesian Coal Basin), Arch. Min.
Sci., vol. 51, No 4, p. 577-588.
Siemek J., Olajossy A., Rajtar J., Rybicki C., 1990. Zastosowanie metod inżynierii złóż gazu ziemnego do badania
przepływów w pokładach węgla (in Polish), w: Górotwór jako ośrodek wielofazowy – wyrzuty skalno-gazowe,
red. J. Litwiniszyn, T. I, wyd. AGH Kraków.
Received: 26 June 2009