Arch. Min. Sci., Vol. 53 (2008), No 2, p. 183–214

Transkrypt

Arch. Min. Sci., Vol. 53 (2008), No 2, p. 183–214
183
MAREK JASZCZUK*, JAN KANIA*
COAL PRODUCTION COSTS COMPONENTS AND COAL PRICE AS CRUCIAL FACTORS
IN THE DESIGNATION OF COAL OUTPUT
SKŁADNIKI KOSZTÓW POZYSKANIA WĘGLA I JEGO CENA JAKO CZYNNIKI DECYZYJNE
W USTALANIU WIELKOŚCI WYDOBYCIA
Due to diverse geological and mining conditions of specific longwalls, amortization of mining
machinery, as well as costs structure in different coal mines, daily coal output should be designated for
each longwall face separately. In view of definite reserves of a given longwall panel, daily coal output
determines its extraction time, thus, the analysis should also consider the time factor.
Unlike popular cost allocation methods in accordance with the criteria of the relations between
costs and changes in coal output, the proposed method is based on a different approach to a longwall
face, including the analysis of the costs of the preparatory works stage previous to extraction works. The
inclusion of the time factor has led to the derivation of three costs categories: absolutely fixed costs KBS,
relatively fixed costs KWS, variable costs KZ.
On the grounds of the above mentioned three costs categories an economic model was designed,
enabling the designation of daily coal output depending on the reserves of a given longwall panel and
its extraction time, for the assumed profit level, or for the assumed balance between the costs of coal
production and the incomes from coal sales. The model incorporates the total costs of coal production,
including all stages of the production process: preparation works of the longwall panel, longwall moves,
extraction works, longwall shut down.
The grounds for the model, in accordance with the assumed methodology, were provided by economic
modelling used in diagnosing critical functional zones of longwall faces or coalmines.
The three dimensional model used for designating daily coal output from a given longwall face is
derived as function Q = ƒ(t, Zp) describing the surface of daily coal production Q and a function in the
form of a line of intersection equation (1) constituting a boundary line between two intersecting surfaces
Q and Q1:
Zp
ì
ïï Q = t
Rk : í
k × t + K BS
ï Zp = WS
ïî
CZ - k Z
*
(1)
SILESIAN UNIVERSITY OF TECHNOLOGY, FACULTY OF MINING AND GEOLOGY, INSTITUTE OF MINING MECHANIZATION, UL. AKADEMICKA 2, 44-100 GLIWICE, POLAND
184
where:
Q
Zp
kWS
t
KBS
CZ
kZ
—
—
—
—
—
—
—
daily coal output [t/day],
coal reserves of the longwall field [t],
relatively fixed costs related to the time unit [PLN/day],
extraction time [day],
absolutely fixed costs [PLN],
sale price for one ton of produced coal [PLN/t],
elementary variable costs, variable costs related to a ton of produced coal [PLN/t].
The economic model involves the required daily output treated as an explained (dependent) variable
and longwall coal resources and extraction time as explanatory (independent) variables. Other impact
factors were expressed as model parameters. The selection of coal reserves and extraction time as the
explanatory variables predominantly resulted from the assumed method of determining daily coal output
in consideration of the simultaneous change in coal reserves and extraction time.
The analysis of the possibilities of obtaining high concentration of extraction under definite mining and
geological conditions of a given longwall face requires a model that should make it possible to designate
the coal output in view of the technical potential of the longwall system. If it is assumed that the coal
output is mainly conditioned by the technical parameters of the shearer loader, the model of the production process in the longwall may be utilized, as it includes: theoretical capacity of the shearer loader, the
degree of its utilization under given mining conditions, parameters of the longwall face, actual worktime
of mining machinery on a face, cutting sequence.
Thus, the analysis entails the technical, organizational and technological aspects.
Considering a different course of the production process in the longwall, related to a specific nature
of the two basic cutting sequences, the daily coal output from the longwall may be calculated as:
WQ = Qt . T . ψT . ηt
where:
Qt
T
ψT
ηt
—
—
—
—
(2)
theoretical capacity of the shearer loader,
available worktime of mining machinery on a face,
index of worktime availability,
operational efficiency index.
The theoretical capacity of the shearer loader under given mining conditions is derived from the
following equation, in consideration of the technical parameters of the shearer loader (vmax, z) and other
parameters associated with the natural conditions and a given extraction system (H, γ):
Qt = H . z . vmax . ρ
where:
H
z
Vmax
ρ
—
—
—
—
(3)
longwall height,
nominal width of web,
maximal haulage speed,
coal density.
The analysis of the costs components as a crucial factor for designating the coal output was made in
exemplary longwall faces in coal mine “X”. The economic model of the costs balance was used in the
analysis, as well as the model enabling the designation of coal output from the technical potential of the
longwall system and the proposed costs allocation system related to the longwall workings in consideration
of the actual structure of the coal mine. The possibility of achieving the required coal output was examined
for each longwall face in view of the balance between the production costs and incomes from sales.
Due to the range of the analysis entailing all the costs components of coal production, including:
preparation of the longwall field, moves of the technical equipment, extraction of the longwall face, basic
production processes in the underground section and the surface section, sales costs and overheads, six
longwalls were selected for the analysis under different mining and geological conditions and various
mining equipment.
The impact of the daily output to changes in the values of the costs components and coal sales prices
was assessed in the course of the sensitivity analysis.
185
The results indicate that the greatest impact on the change in the required daily output is exerted by
the sale price of coal.
Forecasts of coal sale prices at the stage of designing the longwall face are difficult, because the
sale price does not only depend on the quality of coal, but also on management decisions undertaken by
a given coal company and on some external conditions.
Relatively fixed costs constitute another factor that exerts an important impact on daily coal output.
For the longwalls with extensive coal field length and, consequently, long extraction time, where
the contribution of relatively fixed costs is the biggest, the main objective is to provide a higher degree
of the utilization of the face production potential, which would facilitate the balance between the costs
and incomes. In the case of longwall faces with short coal field length and short extraction time, the
contribution of relatively fixed costs is smaller.
Absolutely fixed costs and variable costs have a certainly smaller contribution. The impact of absolutely fixed costs depends; to a large extend, on the coal field length.
The sensitivity analysis indicated that for the longwalls with short coal field lengths, the impact of
absolutely fixed costs is certainty stronger than for those with extensive coal field lengths, which is caused
by a significantly bigger contribution of these costs in the total costs of coal production. Accordingly,
in case of shorter coal field lengths, special attention should be drawn to the costs of the preparatory
operations and longwall moves.
Keywords: coal production costs components, crucial factors, economic model, longwall face, economic
efficiency, daily output, technical potential of longwall systems
Ze względu na zróżnicowanie: warunków geologiczno-górniczych poszczególnych wyrobisk, stopnia
amortyzacji maszyn i urządzeń górniczych, struktury kosztów w poszczególnych kopalniach, wielkość
wydobycia dobowego powinna być wyznaczona indywidualnie dla każdej ściany. Ponieważ przy określonych zasobach pola ścianowego wyznaczona wielkość wydobycia dobowego determinuje czas jego
eksploatacji w analizie należy uwzględnić również czynnik czasu.
W odróżnieniu od dotychczas stosowanego podziału kosztów zgodnie z kryterium reakcji kosztów
na zmianę wielkości produkcji zaproponowano odmienne podejście w odniesieniu do wyrobiska ścianowego, uwzględniające także reakcję kosztów na zmianę czasu eksploatacji pola ścianowego, przy objęciu
analizą kosztów etapu przygotowania pola do eksploatacji. Uwzględnienie czynnika czasu spowodowało
uzyskanie trzech kategorii kosztów: koszty bezwzględnie stałe KBS, koszty względnie stałe KWS, koszty
zmienne KZ.
W oparciu o przedstawione powyżej kategorie kosztów opracowano model ekonomiczny, który
pozwala na wyznaczenie wymaganego wydobycia dobowego w zależności od zasobów pola ścianowego i czasu jego eksploatacji dla założonego poziomu zysku lub równowagi kosztów pozyskania węgla
i przychodów uzyskanych z jego sprzedaży. W modelu uwzględniono całkowity koszt pozyskania węgla
obejmujący wszystkie etapy procesu produkcyjnego: przygotowanie pola ścianowego, zbrojenie ściany,
prowadzenie eksploatacji, likwidację pola ścianowego.
Podstawą opracowania modelu, spełniającego założenia przyjętej metodologii, stanowi modelowanie
ekonomiczne, stosowane do badania krytycznych obszarów funkcjonowania przodka ścianowego lub
kopalni.
Usytuowany w trójwymiarowej przestrzeni model do wyznaczania wydobycia dobowego z wyrobiska
ścianowego opisany jest funkcją Q = ƒ(t, Zp) przedstawiającą powierzchnię wydobycia dobowego Q
oraz funkcją w postaci równania krawędziowego (1) stanowiącą linię graniczną, dwóch przecinających
się powierzchni Q i Q1:
Zp
ì
Q=
ïï
t
Rk : í
k × t + K BS
ï Zp = WS
CZ - k Z
îï
(1)
186
gdzie:
Q
Zp
kWS
t
KBS
CZ
kZ
—
—
—
—
—
—
—
wydobycie dobowe [t/d],
zasoby analizowanego pola ścianowego [t],
koszty względnie stałe odniesione do jednostki czasu [zł/d],
czas prowadzenia eksploatacji w polu ścianowym [d],
koszty bezwzględnie stałe [zł],
cena zbytu tony pozyskanego węgla [zł/t],
jednostkowe koszty zmienne, koszty zmienne odniesione do tony pozyskanego węgla [zł/t],
W opracowanym modelu ekonomicznym wyodrębniono: wymagane wydobycie dobowe jako zmienna
objaśniana, a zasoby pola ścianowego i czas eksploatacji jako zmienne objaśniające. Pozostałe wzajemnie
przenikające się czynniki wpływu zostały sparametryzowane i uwzględnione jako parametry w modelu.
Wybór zasobów pola ścianowego i czasu eksploatacji jako zmiennych objaśniających wynikał głównie
z przyjętej metody wyznaczania wydobycia dobowego uwzględniającej w swej procedurze jednoczesną
zmianę zasobów pola ścianowego i czasu jego eksploatacji.
Przeprowadzenie analizy dotyczącej możliwości uzyskania wysokiej koncentracji wydobycia
w warunkach geologiczno-górniczych konkretnego wyrobiska wymaga dysponowania również modelem
pozwalającym na wyznaczenie wielkości wydobycia wynikającego z potencjału technicznego systemu
mechanizacyjnego. Zakładając, że wydobycie to uwarunkowane jest głównie parametrami technicznymi kombajnu ścianowego można posłużyć się modelem przebiegu procesu produkcyjnego w przodku
ścianowym, który uwzględnia: teoretyczną wydajność kombajnu i stopień jej wykorzystania w danych
warunkach eksploatacyjnych, parametry wyrobiska ścianowego, dyspozycyjny czas pracy maszyn w wyrobisku i stopień jego wykorzystania, technologię urabiania kombajnem.
Dzięki temu analiza obejmuje wpływ czynników natury: technicznej, organizacyjnej, technologicznej.
Biorąc pod uwagę odmienny przebieg procesu produkcyjnego w ścianie, związany ze specyfiką
obu podstawowych technologii urabiania kombajnem, wydobycie dobowe ze ściany można wyznaczyć
z zależności:
gdzie:
Qt
T
ΨT
ηt
—
—
—
—
(2)
teoretyczna wydajność kombajnu,
dyspozycyjny czas pracy maszyn w wyrobisku,
stopień wykorzystania dyspozycyjnego czasu pracy maszyn w wyrobisku,
wskaźnik sprawności technologii.
Teoretyczna wydajność kombajnu w warunkach danej ściany wyznaczana jest z uwzględnieniem
parametrów technicznych kombajnu (vmax, z) oraz parametrów związanych z warunkami naturalnymi
i systemem eksploatacji (H, γ) z następującej zależności:
(3)
gdzie:
H — wysokość ściany,
z — szerokość zabioru kombajnu,
vmax — maksymalna robocza prędkość posuwu,
ρ — masa właściwa węgla
Przeprowadzono analizę składników kosztów jako czynnika decyzyjnego w ustalaniu wielkości
wydobycia na przykładzie wybranych przodków ścianowych prowadzonych w KWK „X”. W analizie
wykorzystano opracowany model ekonomiczny równowagi kosztów i model pozwalający na wyznaczenie
wielkości wydobycia wynikającego z potencjału technicznego systemu mechanizacyjnego oraz zastosowano zaproponowany sposób podziału kosztów w odniesieniu do wyrobisk ścianowych uwzględniający
rzeczywistą strukturę kopalni. W odniesieniu do każdej ściany ustalono możliwość uzyskania wydobycia
w aspekcie zrównoważenia kosztu pozyskania węgla z przychodami.
Ze względu na zakres prowadzonych badań analitycznych obejmujących wszystkie składniki kosztów
pozyskania węgla związanych z: przygotowaniem pola ścianowego, relokacją wyposażenia technicznego
w okresie zabudowy i wybudowy, eksploatacją wyrobiska ścianowego, podstawowymi procesami produk-
187
cyjnymi w części podziemnej i na powierzchni kopalni oraz kosztami sprzedaży i ogólnozakładowymi
do analizy wybrano sześć ścian, prowadzonych w zróżnicowanych warunkach geologiczno-górniczych
i przy zastosowaniu odmiennego wyposażenia technicznego.
Na podstawie analizy wrażliwości wydobycia dobowego na zmiany wartości analizowanych składników kosztów i ceny zbytu ustalono siłę ich oddziaływania.
Na podstawie uzyskanych wyników stwierdzono że, największy wpływ na zmianę wymaganego
wydobycia dobowego ma cena zbytu.
Prognozowanie ceny zbytu węgla na etapie projektowania przodka ścianowego jest jednak trudne,
gdyż wartość ta nie zależy tylko od jakości węgla, czy też od decyzji zarządczych zakładu górniczego
ale także jest uwarunkowana czynnikami zewnętrznymi.
Kolejnym czynnikiem istotnie wpływającym na wydobycie dobowe są koszty względnie stałe.
W ścianach o długim wybiegu, a tym samym długim okresie eksploatacji, w których udział kosztów
względnie stałych jest największy należy dążyć do uzyskania większego stopnia wykorzystania potencjału
produkcyjnego ściany, co sprawia, że łatwiej będzie można uzyskać równowagę pomiędzy kosztami
a przychodami. W przypadku przodków ścianowych o krótkich wybiegach i krótkim okresie eksploatacji
udział kosztów względnie stałych jest mniejszy.
Zdecydowanie mniejszy wpływ mają koszty bezwzględnie stałe i zmienne. Siła oddziaływania
kosztów bezwzględnie stałych zależy w dużej mierze od wybiegu ściany.
Przeprowadzona analiza wrażliwości wykazała, że w przypadku ścian o krótkich wybiegach siła oddziaływania kosztów bezwzględnie stałych jest zdecydowanie większa w porównaniu ze ścianami o długich
wybiegach, co wynika ze znacznie większego udziału tych kosztów w kosztach całkowitych pozyskania
węgla. W związku z powyższym w przypadku krótkich wybiegów ścian należy zwrócić szczególną uwagę
na przebieg i koszty operacji przygotowania pola ścianowego i zbrojenia ściany.
Słowa kluczowe: składniki kosztów pozyskania węgla, czynniki decyzyjne, model ekonomiczny, przodek ścianowy, efektywność ekonomiczna, wydobycie dobowe, potencjał techniczny
systemu mechanizacyjnego.
List of the most important notations:
CZ
KBS
KCP
KWS
KZ
KZ, KK, KT
Q1-Qn
RK
RT
RZ
TZ,TK,TT
ZZ, ZK, ZT
–
–
–
–
–
–
–
–
–
sale price of a ton of produced coal [PLN/t],
total costs of coal production for the analyzed longwall field [PLN],
relatively fixed costs [PLN],
variable costs [PLN],
graph of the function of the fixed costs of coal production (iso-costs),
graph of the function of the fixed coal production (iso-concentration),
costs break-even point under the fixed costs of coal production,
costs break-even point under the fixed extraction time of the longwall
field,
– costs break-even point under the fixed reserves of the longwall field,
– graph of the function of the fixed extraction time of the longwall field,
lines of fixed extraction time,
– graph of the function of the fixed reserves of the longwall (iso-quants).
188
1. Introduction
To facilitate the analysis of the economic efficiency of coal extraction from the longwall face a model enabling the designation of daily coal output was devised, securing the
achievement of the assumed profit or the balance between the costs of coal production
and incomes from sales for a specific longwall.
The proposed procedure involves the following stages:
• designation of the daily coal output in relation to the economic, mining and geological conditions;
• designation of the daily coal output in relation to the production potential of mining machinery and organizational factors for a specific longwall,
• determination of the conditions of efficient extraction on the grounds of the comparison between the two coal output quantities mentioned above.
If, on the grounds of the potential of the longwall system, it is impossible to designate
such coal output that secures the economic efficiency, the analysis should focus on the
option of reducing the costs of coal production. Such conclusion stems from the fact
that after the possibilities of the longwall field are explored (resources) in consideration
of a given production potential of the mining equipment at the coal company’s disposal,
this is the only way to improve efficiency. Accordingly, the particular components of
the costs of coal production and the price of sale are the crucial factors in determining
the coal output under specific longwall conditions.
2. The economic model of the balance between the costs of coal production
and incomes from sales for a specific longwall
In view of diverse geological and mining conditions prevailing in particular longwalls,
the degree of amortization of mining machinery and the costs structure in the coal mine,
the daily coal output should be designated for each longwall separately. With given coal
reserves of the longwall field, the designated daily coal output determines the time of
the longwall extraction. Thus, the analysis should also include the time factor.
Unlike generally recognized costs allocation methods in accordance with the criteria
of the relations between the costs and the changes in coal output, the proposed method is
based on a different approach to a longwall face, including the response of the costs to
the change in the extraction time of the longwall face, and in consideration of the costs
of the preparatory operations previous to extraction works (Jaszczuk & Kania, 2007).
The inclusion of the time factor has led to the derivation of three costs categories:
• absolutely fixed costs KBS, which are the costs of the preparation of the longwall
field for mining, these costs may change rapidly, due to different technologies of
driving roads and the adoption of different organization and the technical means
used in moving the longwall equipment for further longwall cut-through.
189
• relatively fixed costs KWS, entailing the costs of the functioning of the spatial underground structure of the coal mine. The extraction time of the coal field depends on
the achieved daily coal output and the reserves of the longwall field. Its variability
may result from the intensity of mining, associated, for example, with seasonal
demand for coal, or, with the occurrence of other factors limiting coal output,
• variable costs KZ which are proportional to the changes in coal output and to the
scope of the activity of the coal mine.
On the bases of the above mentioned costs categories, the devised economic model
(Jaszczuk & Kania, 2007) makes it possible to determine the required daily coal output
in relation to the reserves of the longwall field and its extraction time for the assumed
profit level or for the assumed balance between the costs of coal production and the
incomes from coal sales. The model takes into account the total costs of coal production, including all stages of the production process: the preparatory operations, longwall
moves, extraction, closing down of the longwall.
The model fulfilling the assumptions of the accepted methodology was based on
economic modelling used in testing critical functional zones of longwall faces or coal
mines (Jabłońska-Firek, 1999; Madga, 1999).
The three dimensional model used for determining the daily coal output from a given
longwall face is derived as function Q = ƒ (t, Zp) describing the surface of daily coal
production Q, and a function in the form of a line of intersection equation (2.1) constituting a boundary line between two intersecting surfaces Q and Q1 (Fig. 2.1):
Zp
ì
ïï Q = t
Rk : í
k × t + K BS
ï Zp = WS
ïî
CZ - k Z
where:
Q
Zp
kWS
t
KBS
CZ
kZ
—
—
—
—
—
—
—
(2.1)
daily coal output [t/day],
coal reserves of the longwall field [t],
relatively fixed costs related to the time unit [PLN/day],
extraction time [day],
sale price for one ton of produced coal [PLN/t],
elementary variable costs, variable costs related to a ton of produced coal
[PLN/t].
The economic model involves the required daily output treated as an explainable
variable and the coal field reserves and extraction time as explanatory variables. Other
impact factors were expressed as model parameters. The selection of coal reserves and
extraction time as the explanatory variables predominantly resulted from the assumed
190
nce
put
bala aily out
d
cost
e of onstant ace
in
L
c
f
face
R k - Line of tput sur nce sur
u
Q 1-n - Daily o tput bala
u
ily o
Q
- Da
Q1
Required daily output [t/day]
8000
7000
6000
5000
Q
Q1
4000
3000
2000
Rk
1000
0
0
100
Q4
Q3
Q2
Q1
Q5
Q6
Q7
Q8
Q9
Q10
Q11
Q12
0
200
Long
300
wall
400
rese
500
rves
600
[10 3
t]
700
800
150
Long
90
120
wall
p
exp
anel
30
60
olita
t
ime
ion t
[day
]
Fig. 2.1. Break-even lines in the three dimensional model
Rys. 2.1. Usytuowanie linii równowagi
method of designating the daily coal output in consideration of the simultaneous change
in the coal reserves and the extraction time.
Another approach to the issue was proposed in (Brzychczy, 2006), where the bases
of the mathematical model derived for the optimization of mining works in a hard coal
mine with the use of stochastic networks. The model includes the mathematical relations describing future mining works in consideration of the characteristics of particular
technological operations.
3. Designation of the daily coal output conditioned by the technical
potential of the longwall system
The analysis focused on the possibilities of achieving a high concentration of extraction under the mining and geological conditions of a specific longwall also requires
a model that would enable the designation of the coal output in view of the technical
potential of the longwall system.
Assuming that the coal output is primarily conditioned by the technical parameters
of the shearer loader, a model of the production process in the longwall may be utilized,
191
as it considers: the theoretical capacity of the shearer loader, the degree of its utilization
under given mining conditions, the parameters of the longwall face, actual worktime of
mining machinery on a face, the cutting sequence.
Thus, the analysis entails the technical, organizational and technological aspects
(Magda et al., 1992).
Considering a different course of the production process in the longwall, related
to a specific nature of the two basic cutting sequences, the daily coal output from the
longwall may be calculated as:
where:
Qt
T
ψT
ηt
—
—
—
—
(3.1)
theoretical capacity of the shearer loader,
available work time of mining machinery on a face,
index of work time availability,
operational efficiency index.
The theoretical capacity of the shearer loader under given mining conditions is derived from the following equation, in consideration of the technical parameters of the
shearer loader (vmax, z) and other parameters associated with the natural conditions and
a given extraction system (H, γ):
where:
H
z
vmax
ρ
—
—
—
—
(3.2)
longwall height,
nominal width of web,
maximal haulage speed,
coal density.
The technological efficiency ratio is derived from the following equations:
• unidirectional cutting sequence:
ht =
kQ × L × h
æ
v æ
(L - lk ) × çç1 + u çç × (1 + pz )
v
m è
è
(3.3)
• bidirectional cutting sequence
æ z ×v æ
2 × kQ × L × h × çç1 + p p çç
z z × vz è
è
ht =
æ v æ æ v æ
(L - lk ) × çç1+ z çç × çç1 + p çç × (1 + pz )
è v p è è vz è
(3.4)
192
If the width of web at both trips in bidirectional cutting is the same or comparable,
the following simplified relation may be used:
ht =
where:
kQ
L
lk
pz
vu, vm
vz, vp
zz, z p
—
—
—
—
—
—
—
2 × kQ × L × h
æ
v
(L - l k ) × çç1 + z
vp
è
æ
ç × (1 + pz )
ç
è
(3.5)
index of theoretical capacity utilization of the shearer,
longwall length,
length of shearer loader,
index of technological operations contribution,
haulage speed of the shearer in a course of cutting and return trip,
haulage speed of the shearer in downstream and upstream cutting trips,
width of the web of the shearer in downstream and upstream cutting
trips.
The index of theoretical capacity utilization of the shearer relates to the real average
efficiency of the shearer, resulting from the effective width of web (ze) and from the
value of mean haulage speed achieved in the course of cutting under given operational
conditions (v), to the theoretical capacity of the shearer. It reflects the utilization of
potential technical possibilities of the shearer in the longwall face and is calculated for
unidirectional sequences only in a cutting trip, whereas for bidirectional ones both in
downstream and upstream cutting trips, from the following equation:
kQ =
ze × v
z × vmax
(3.6)
Due to a specific nature of both cutting sequences and different state of the external
load of the shearer, resulting, first and foremost, from the process of loading, the shearer
achieves different haulage speeds for downstream and upstream trips. This factor is
considered in the designation of the technological efficiency ratio by the quotient of the
mean values of haulage speed achieved for both cutting directions (vz /vp, vp /vz for the
bidirectional cutting sequence and vu /vm for the unidirectional sequence).
All the above mentioned parameters (Qt, kQ, vz /vp or vu /vm) represent the technical
factors in the model.
Another important aspect considered in the model is the effective production time
of the shearer (the theoretical capacity utilization), which is both an organizational and
a technical factor. The effective production time is the resultant of: available worktime
of mining machinery on a face (T ) and the degree of this time utilization (ψT).
The available worktime of mining machinery on a face stems from the accepted
form of production organization (number of shifts, number of production shifts), the
193
requirements connected with the operational conditions prevailing in the longwall and
the distance between the longwall and the shaft. Its full utilization may be limited by
unplanned downtime caused by mining, technical or organizational reasons.
In the analysis of the possibilities of achieving a definite daily coal output it is also
essential to pay attention to the duration of sumping operations in relation to the mean
time of cutting operations (bidirectional sequences) or total cutting time and return trip
(unidirectional sequences). Thus, the index of technological operations contribution,
derived from the following equation was introduced to the model:
• unidirectional cutting sequence
pz =
Tpz × vu
æ v æ
(L - lk ) × çç1 + u çç
è vm è
(3.7)
• bidirectional cutting sequence
pz =
2 × Tpz × vz
æ
v æ
(L - l k ) × çç1 + z çç
v
p è
è
(3.8)
where Tpz – is the duration of the sumping operations in a given production cycle.
For a definite duration of the sumping operations (Tpz) its impact on the possibility
of achieving a high concentration of coal output, for the same degree of the utilization
of the technical capacity of the shearer loader, depends on the applied cutting sequence
and the length of the longwall.
The value of the technological efficiency index makes it possible to determine
which part of the potential daily coal output, derived from the theoretical capacity of
the shearer under specific mining conditions and from the real production time of the
shearer during 24 hours (T • ψT), is the daily output that may be obtained for the applied
cutting sequence.
On the grounds of the values of this index, it is possible to trace the influence of particular factors associated with the utilization of the theoretical capacity of the shearer loader,
the duration of the sumping operations and the length of the longwall, on the possibility
of achieving a high concentration of extraction for the applied cutting sequence.
The analysis of the values of the technological efficiency index in relation to the two
basic cutting sequences and depending on the selected impact factors was conducted on
the grounds of underground tests (Jaszczuk, 1999). For shearer loaders with only one
range of haulage speed, the technological efficiency index for unidirectional sequence
was 0.17÷0.27, whereas for bidirectional sequences: 0.25÷0.43. A high concentration of
coal output for unidirectional sequence may be achieved if the shearer loader with two
194
ranges of haulage speed is used: the cutting one and the manoeuvring one. Accordingly,
the value of the technological efficiency index is increased to 0.33÷0.44.
For bidirectional sequences, an increase of the longwall length leads to a better
improvement of the technological efficiency index in comparison with unidirectional
sequences; at the same time, the higher the haulage speed, the more significant improvement of the technological efficiency index. Such improvement also depends on the
duration of the sumping operations.
4. The use of the economic model for designating the conditions of effective
and efficient coal extraction from longwalls on the example
of selected faces in coal mine: “X”
In this chapter, the costs components as decisive factors in designating the coal
output are analyzed on the example of selected longwalls mined in hard coal mine X.
The analysis is based on the economic model of the costs balance and is followed by
a proposal of costs allocation in relation to the longwall faces and in consideration of the
underground structure of real mines. Possibilities of achieving certain coal outputs are
examined for each longwall in view of the balance between the costs of coal production
and the incomes from coal sales.
Due to the scope of the analytical studies on all the costs components of coal extraction including: the preparatory operations, the longwall moves, the extraction of coal,
the basic production processes in the underground part of the mine and on its surface,
and the costs of sales and overheads, six longwall faces were selected, with different
geological and mining conditions and different technical equipment applied. The following longwalls were analyzed:
• longwall No 1A, the mean height of which is 2.2 m, the length of 245 m, longitudinal inclination of 5o and the longwall panel length of 927 m, equipped with: new
KGS-345/2PB shearer loader and a new PF-4/2.2/743M armoured face conveyor
and modernized Glinik-08/26-Oz-TL-ZBMD powered roof support;
• longwall No 1B, the mean height of which is 2,16 m, the length of 246 m, longitudinal inclination of 7o and the longwall panel length of 1140 m, equipped with
the same longwall system as this installed in longwall 1A (see above);
• longwall No 2A, the mean height of which is 2.08 m, the length of 250 m, longitudinal inclination of 13.7o and the longwall panel length of 489 m, equipped
with the refurbished longwall system including: KGS-410/2PB shearer loader and
RYBNIK-225/750/85-250/BP/K-315 armoured face conveyor, and Glinik-08/26Oz-K powered roof support;
• longwall No 2B, the mean height of which is 2,28 m, the length of 216 m, longitudinal inclination of 16.5o and the longwall panel length of 447 m, equipped with
the same longwall system as this installed in longwall 2A (see above);
195
• longwall No 3B, the mean height of which is 1.45 m, the length of 244 m, longitudinal inclination of 5o and the longwall panel length of 765 m, equipped with:
KSE-360 shearer loader, GSW-PS-750/2x85-250/BP armoured face conveyor and
refurbished Glinik-066/16-OzK powered roof support;
• longwall No 3C, the mean height of which is 1.62 m, the length of 214 m, longitudinal inclination of 5o and the longwall panel length of 572 m, equipped with
the refurbished system including: KGS-245/2PB shearer loader and RYBNIK225/750/85-250/BP/K-200 armoured face conveyor, and Glinik-066/16-Oz-K
powered roof support.
The mining and geological conditions prevailing in the above longwall faces are as
follows:
• longwalls 1A, 1B, situated in the seam with the thickness of 1.65-2.20 m, inclination of 0o-12o and coal cutability of 1.56 (according to Protodiakonov’s scale) were
mined longitudinally with roof caving. The roof rocks were classified as class II
and class III. As far as mining hazards are concerned, the seam was classified as:
2nd degree of water-related hazards, class A of coal dust explosive conditions, group
II of coal self-ignition conditions, as methane-free seam. There were no bounce,
radiation, gas or rock breakout hazards.
• longwalls 2A, 2B, situated in the seam with the thickness of 1.7-2.2 m, inclination
of 0o-5o and coal cutability of 1,36 (according to Protodiakonov’s scale) were mined
longitudinally with roof caving. The roof rocks were classified as class II and, at
some sites as class I or III. As far as mining hazards are concerned, the seam was
classified as: 1st degree of water-related hazards, class A of coal dust explosive
conditions, group II of coal self-ignition conditions, as methane-free seam. There
were no bounce, radiation, gas or rock breakout hazards.
• longwalls 3B, 3C, situated in the seam with the thickness of 1.1-1.4 m, inclination of 0o-6o and coal cutability of 2.2 (according to Protodiakonov’s scale) were
mined longitudinally with roof caving. The roof rocks were classified as class II
and class III. As far as mining hazards are concerned, the seam was classified as:
1st degree of water-related hazards, class A of coal dust explosive conditions, group
II of coal self-ignition conditions, as methane-free seam. There were no bounce,
radiation, gas or rock breakout hazards.
In longwalls No 1A and 1B, categorized as medium height, KGS-345N/2PB shearer
loader prototype was installed, and refurbished Glinik-08/26-Oz-TL-ZBMD powered
roof support. The refurbishment of the powered roof support included the elongation
of the roof canopies and the advancing unit. Longwalls 2A and 2B, belonging as well
to the medium height category and differing from 1A and 1B because of shorter panel
length, were equipped with the machinery at the disposal of the coal mine. It should be
emphasised that the powered roof support units did not have elongated roof bars, and
no advancing unit adjusted to the width of web equal to 0.8 m.
Face
number
1
1A
1B
2A
2B
3A
3B
3C
No.
0
1
2
3
4
5
6
7
IV
V
VI VII VIII IX
X
XI XII
I
II
III
IV
V
VI VII VIII IX
Longwall move – operation
III
Raise driving
II
4
3
Roadway driving
I
1996
1995
X
XI XII
I
II
III
IV
V
X
XI XII
I
Month
Year
II
Longwall shut down
Extraction works
VI VII VIII IX
5
1997
III
IV
V
VI VII VIII IX
6
1998
Schedule of the preparatory, longwall move and mining operations in 1995-2000
Roadway driving
Longwall shut down
Roadway driving XXXIV
Roadway driving XXXIII
Raise driving
Extraction works
Longwall shut down
Roadway driving XXXIII
Roadway driving XXXII
Raise driving
Extraction works
Longwall shut down
Roadway driving IVS
Roadway driving IIIS
Raise driving
Extraction works
Longwall shut down
Roadway driving VS
Roadway driving IVS
Raise driving
Extraction works
Longwall shut down
Roadway driving IVN
Roadway driving IIIa
Raise driving
Extraction works
Longwall shut down
Roadway driving VN
Roadway driving IVN
Raise driving
Extraction works
Longwall shut down
Roadway driving VS
Roadway driving IVS
Raise driving
Extraction works
2
Works specification
X
XI XII
I
II
III
IV
V
VI VII VIII IX
7
1999
X
XI XII
Harmonogram robót przygotowawczych, zbrojeniowych i eksploatacyjnych w latach 1995÷2000 w kopalni X
Schedule of the preparatory, longwall move and mining operations in 1995÷2000 in the coal mine X
I
II
III
IV
V
VI VII VIII IX
8
2000
X
XI XII
TABLICA 4.1
TABLE 4.1
196
197
Longwalls 3B and 3C, with similar geometric parameters, were equipped with the
powered roof support systems with differentiated technical parameters and different
operational lifes.
The dimensions of the coal fields (longwall length, panel length) in the case of all
longwall faces were as big as possible to achieve, in consideration of their geological,
and mining conditions and extraction history.
Accordingly, it was impossible to extend the coal reserves of the longwall fields. The
analysis of the costs, on the bases of selected faces of mining in coal mine X, includes
all the operations (preparatory, longwall moves, extraction) in 1995-2000 under the
schedule presented in Table 4.1.
The analysis included the cost indexation in accordance with the inflation rate in the
examined period by referring the costs to the year 2000.
The indexation, including the inflation rate, was also made for the price of coal sales,
treated as a fixed quantity in the analysis.
The parameters characterising particular longwall faces and their economic efficiency
were compiled in Table 4.2.
Longwall 1A was extracted for about 11 months, during which there were 225 coal
production days. The total time from the longwall cut-through to the longwall machinery move lasted for 32 months. The length of the roadways covering the coal field of
TABLE 4.2
The parameters describing the economic efficiency of coal extraction
TABLICA 4.2
Parametry wyznaczające warunki efektywnej eksploatacji
Main parameters of effective extraction
No. Specification
1
Real extraction time
Number of face
Notation
Unit of
measure
1A
1B
2A
2B
3A
3B
3C
t
[d]
225
352
98
113
209
213
179
142 777
2
Real coal reserves of longwall field
Zp
[t]
527 600
515 700
276 802
209 429
318 900
221 641
3
Coal output contamination
K
[%]
29
38
23
28
31
40
52
4
Real longwall panel lenght
Lw
[m]
927
1 140
489
447
950
765
572
Q
[t/d]
2 345
1 465
2 825
1 853
1 526
1 041
798
Q GR
[t/d]
3 529
5 568
2 311
1 986
3 283
2 792
1 826
Required daily output for fixed extraction time
QT
[t/d]
3 802
5 811
2 808
2 443
3 649
3 071
2 207
Required daily output for fixed total costs
QK
[t/d]
3 837
5 899
2 807
2 467
3 699
3 116
2 269
Required daily output for fixed reserves of
longwall panel
QZ
[t/d]
3 994
6 673
2 804
2 636
4 325
3 821
3 497
10 Required extraction time for fixed total costs
TK
[d]
200
258
98
107
184
183
154
Required extraction for fixed reserves of
longwall panel
Required reserves of longwall panel for fixed
12
extraction time
Required reserves of longwall panel for fixed
13
total costs
TZ
[d]
132
77
99
79
74
58
41
Zp T
[t]
855 508 2 045 406 275 177
274 040
762 730
654 040
395 040
Zp K
[t]
766 594 1 522 185 275 511
264 670
681 090
570 860
349 560
14 Required longwall panel lenght
LwZ
[m]
1 087
2 204
410
418
1 570
1 255
777
Required haulage speed of a shearer loader
15
with consideration of coal contamination
υ QZ
[m/min]
4,40
8,20
3,60
3,20
8,00
7,00
8,30
5
Real output
6
Required daily output
7
8
9
11
198
longwall faces 1A and 1B is shown in Fig. 4.1, as well as the lengths of the gate and tail
roads that were driven to secure the progress of further extraction works, which was
reflected in the costs of their driving and maintenance.
o 1A
- 24
510
m
oX
XXIV
- 97
2m
+2
50 m
=1
222
m
oI-
yN
0m
eN
ne N
dwa
60 m
- 13
XXII
oX
yN
dwa
Roa
Lo
g w a ngwa
ll pa ll fac
e
nel
leng No 1B
ht 114
Lon
Rais
incli
Roa
rder
Roa
Lon Longw
dwa
gwa
a
yN
ll pa ll face
oX
N
nel
XXII
leng o 1A
I-1
ht 237
927
m
m
Boa
6m
ay
Rais
Inclined drift No III
eN
w
ad
o 1B
Inclined dr
- 24
ing
ro
er
t
wa
6m
De
ift No IV
Ventilating
roadway
Cross
o IIIa
- cut N
ay
tory
lora
Exp
dw
roa
Cross - cut No III
Fig. 4.1. Diagram of the coal field covering
longwall faces No 1A and 1B
Rys. 4.1. Schemat pola eksploatacyjnego
obejmującego ściany nr 1A i 1B
The economic model used for designating the break-even points determining the
required daily coal output in the costs balance (Fig. 4.2), indicated that, if the criterion of the fixed reserves of the longwall panel is met, the net daily output should be
Qz = 3994 t/day (Table 4.2), which, in consideration of the coal output contamination
amounting to 29%, corresponds to Qz = 5152 t/day.
At the maximal haulage speed of the shearer loader (6.3 m/min) a high concentration
of the coal output may be achieved, if the index of work time availability ψT = 0.5 and
the technological efficiency ratio ηt = 0.5. Considering the fact that, in the long run, the
degree of the utilization of the availability of the machines is real at the level of 50%,
a high concentration of the coal output could be reached if the production potential of
the longwall was used effectively.
199
ZZ ZK ZT KZ
K K TZ K T
Q5
TK
ZZ
10000
ZK ZT KZ
TZ K K
KT
TK
Q5
TK
9000
TT
Q4
Q4
8000
10000
7000
Q3
8000
Q3
RT
4000
Q2
Rk
RK
100
200
1.5
1
x 10
400
t [d]
Rk
RZ
Q2
RT
2000
6
0.5
300
RK
3000
2
R k'
Q1
K CP
5000
4000
RZ
2000
0
0
Q [t/d]
Q [t/d]
6000
6000
Q1
K CP
1000
Zp [t]
0
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
10000
ZZ ZK ZT KZ
KK KT
x 10
Q5
1.8
Q4
TZ
TK Q 5TT
Q4
Q3
KZ
Q2
R k'
1.4
6000
Q3
1.2
Zp [t]
Q [t/d]
KT
1.6
7000
5000
RT
4000
Q2
1
RK
2000
Q1
K CP
1000
TZ
50
100
R
0.6
RZ
TK
150
200
t [d]
R
250
300
350
400
T
ZT
K
0.4
R Z
0.2
TT
ZZ
Q1
ZK
0.8
Rk
3000
0
0
KK
6
2
9000
8000
6
2
x 10
Zp [t]
0
0
50
100
150
200
t [d]
K
CP
250
300
350
400
Fig. 4.2. Designation of the concentration indices of daily coal output (Qz, QK, QT) for longwall face
No 1A in view of the balance between the costs of coal production and incomes from sales
Rys. 4.2. Wyznaczenie wyznaczników koncentracji wydobycia dobowego (Qz, QK, QT) dla ściany
nr 1A w aspekcie zrównoważonego kosztu pozyskania węgla z przychodami
To determine the impact of particular costs components of coal production and coal
sales price on the quantity of the daily coal output, which is a prerequisite of economic
efficiency, the sensitivity analysis was conducted.
As shown in Fig. 4.3, for the analyzed longwall face, the greatest impact on the daily
coal output is exerted by: the sale price of coal and relatively fixed costs; whereas the
impact of absolutely fixed costs and variable costs is considerably smaller. The impact
is proportional to the quantity of the required daily output corresponding to a given
break-even point.
For example, if each cost component is reduced by 20%, the daily coal output may
be decreased by 2.6% for absolutely fixed costs, by 20% for relatively fixed costs, and
by 7.8% of variable costs. On the other hand, an increase of the coal sales price by 20%
translates into the reduction of the required daily coal output by 23.7%; whereas the
200
CZ
8000
7000
6000
RZ
5000
4000
K BS
3000
RK
KZ
RT
2000
1000
K CP
K BS
K WS
KZ
CZ
K WS
0
-1000
-100
-80
-60
-40
-20
0
20
40
60
80
100
Changes in the values of the parameters [%]
Fig. 4.3. Spider diagram of the sensitivity analysis of the daily coal output related to the changes
in the values of the parameters for longwall face No 1A
Rys. 4.3. Wykres pajęczy przedstawiający analizę wrażliwości wydobycia dobowego
na zmiany wartości analizowanych parametrów dla ściany nr 1A
reduction of the sales price by 20% leads to the necessity of increasing the required
daily output by 45%.
In consideration of the above data, it may be stated that the achievement of the required daily coal output that would secure the balance between the production cost and
the incomes from sales for the discussed longwall face would be possible, if the technical potential of the machinery was used effectively, as well as their available work time
in the face. In the case of any disturbances leading to reduced coal output quantities,
measures should be undertaken to reduce relatively fixed costs.
Longwall 1B was extracted for about 18 months, during which there were 352 coal
production days. The total time from the longwall cut-through to the longwall machinery
move lasted for 60 months. It was due to the fact that there was a break lasted 14 months,
which caused absolutely fixed costs increase. This long lasting stoppage resulted in
the roadways support deformation or damage, which was reflected in the costs of their
maintenance. What’s more the coal mine had to cover the additional expenses on the
roadways ventilation and drainage Thus, the total amount of absolutely fixed costs was
much more higher.
The economic model was used for designating the break-even points determining
the required daily coal output in the costs balance (Fig. 4.4). If the criterion of the fixed
reserves of the longwall panel is met, the net daily output should be Qz = 6673 t /day
(Table 4.2), which, in consideration of the coal output contamination amounting to 38%,
corresponds to Qz = 9209 t/day.
201
ZZ
KZ
TZ
ZK
ZT
KK
KT
ZZ
10000
Q5
KZ
TZ
ZK
ZT
Q5
KK
9000
Q4
TK
8000
10000
TT
Q3
Rk
RK
RZ
Q2
4000
R k'
2000
50
100 150
K CP
200 250
300
350 400
t [d]
Z Z K Z TZ
10000
ZK
RT
Q2
Q1
6
1000
Zp [t]
0
KT
KT
4000
2000
x 10
0.5
0
ZT KK
1.5
1
5000
TT
RK
RZ
3000
2
Q1
0
0
Q3
R k'
6000
RT
Q [t/d]
Q [t/d]
8000
6000
Q4
TK
7000
K CP
0
0.2
x 10
Q5
0.4
0.6
0.8
6
1
1.2
Zp [t]
1.4
Q5
Q4
1.6
1.8
2
x 10
6
Q 3 R k'
ZT
2
KT
9000
1.8
TK
8000
Q4
7000
Q [t/d]
RZ
5000
RK
4000
1.4
Q3
R k'
RT
Q2
3000
RK
KZ
1
0.8
Q1
0.6
Q1
2000
1000
0
Q2
ZK
1.2
Zp [t]
TT
6000
RT
1.6
ZZ
0.4
RZ
K CP
0.2
K CP
0
50
100
150
200
t [d]
250
300
350
400
0
TZ
0
50
100
TK
150
200
250
KK
TT
300
350
400
t [d]
No 1B in view of the balance between the costs of coal production and incomes from sales
nr 1B w aspekcie zrównoważonego kosztu pozyskania węgla z przychodami
If the index of work time availability ψT = 0.7 and the technological efficiency ratio
ηt = 0.5 maximal haulage speed of the shearer loader should attain the value of 8.2 m/
min. Considering the fact that, the maximal haulage speed of the shearer loader KGS345 is 6.3 m/min, a high concentration of the extraction could be reached if the further
enterprise was undertaken. For example in the long run, the degree of the utilization of
the availability of the machines is real at the level of 50%, so at the same level of the
technological efficiency ratio (ηt = 0.5) a high concentration of the extraction could be
achieved at maximal haulage speed of the shearer loader vmax = 7.1 m/min, provided that
the reduction of coal output contamination is at least 50%. The results of the analysis
of the possibilities of achieving the state of balance between the production costs and
the incomes from sales by means of the required daily coal output in longwall face
No 1B, under the same technical conditions (shearer loader KGS-345), indicate that it
202
was impossible. So the sensitivity analysis was conducted to determine the impact of
particular costs components of coal production and coal sales price on the quantity of
the daily coal output.
break-even point.
11000
CZ
10000
9000
RZ
8000
7000
6000
5000
4000
K BS
KZ
RK
RT
3000
2000
K BS
K WS
KZ
CZ
K WS
1000
0
-100
K CP
-80
-60
-40
-20
0
20
40
60
80
100
in the values of the parameters for longwall face No 1B
na zmiany wartości analizowanych parametrów dla ściany nr 1B
be decreased by 3.8% for absolutely fixed costs, by 20% for relatively fixed costs, and
by 11% of variable costs. On the other hand, an increase of the coal sales price by 20%
daily output by 57.3%.
In consideration of the above data, it may be stated that, at the same sales price, the
achievement of the balance between the production cost and the incomes from sales
for the discussed longwall face would be achived by reduction of relatively fixed costs.
If the production potential of the longwall was used extremely effectively (ψT = 0.7,
ηt = 0.5, vmax = 6.3 m/min) the coal output could be 5610 t/d, what means that the net
203
Raise No 2A - 250 m
daily output would be Qz = 4060 t/day. Under that conditions the balance between the
production cost and the incomes from sales would be achieved by further reduction of
relatively fixed costs by 14.2%. Increase of coarse-grained coal size would enable to
get higher sales price.
On the results of the analysis of longwall faces No 1A and 1B it could be noticed
that the technical, organizational and economic conditions exert impacts on economic
efficiency. In spite of the fact that both longwall faces:
• were situated in the same seam,
• had almost the same parameters (reserves, height and length),
• were furnished with the same machinery,
only in longwall No 1A the balance between the production costs and incomes from sales
had been achieved. The economic conditions exerted direct impacts on this situation.
During extraction works in the longwall face No 1B sales price was lower of 22% and
at the same time elementary relatively fixed costs were higher of 11%. The other was
caused by higher labour costs and expenses on the roadways maintenance, ventilation
and drainage due to 1,5 times longer extraction time. As a matter of fact the coal output
contamination was higher as well. It may be stated that the achievement of the required
daily coal output that would secure the balance between the production cost and the
incomes from sales for the longwall face No 1B would be possible, if the measures
would have been undertaken to reduce relatively fixed costs, as well as reduction of
coal output contamination.
Longwall 2A was extracted for about 6 months, during which there were 98 coal
Ro
adw
IIIS
-6
ay
No
VS
-5
47
No
I
m
Cro
s
Cro s - cu
ss
tN
-c
oI
ut
No I - 41
0m
II 31
0m
oI
IIN
ift
m
yN
dr
00
wa
ed
-6
Inc
lin
IVS
Ia
ad
No
L
ng ongw
wa
ll p all fa
an
el lece N
ng o 2B
ht
-4
47
m
adw
m
Inc Cros
s
lin
ed - cu
t"
dr
ift
L
No "
II
- 225 m
No 2B
ay
Lo
78
Ro
adw
Raise
No
Lon Lon
gw gwa
all
pan ll fac
el le e No
ngh 2A
t489
m
Ro
Ro
ay
Fig. 4.6 Diagram of the coal field covering longwall
faces No 2A and 2B
Rys. 4.6. Schemat pola eksploatacyjnego obejmującego ściany nr 2A i 2B
204
move lasted for 29 months. There was a break, between the realization of longwall cutthrough to the longwall machinery move, lasted 14 months, which caused absolutely
fixed costs increase. The length of the roadways covering the coal field of longwall faces
2A and 2B is shown in Fig. 4.6.
The achievement of the best daily coal output, among all six analyzed longwall faces,
enabled to get profit level of 0,5% (Fig. 4.7).
If the technical potential of the the net daily output should be Qz = 3994 t /day machinery was used much more effectively, with the mean value of haulage speed of the
shearer loader of 3.5 m/min, the net daily output could have been Qz = 3339 t /day. At
this level of daily output reduction of relatively fixed costs by 14,2% would resulted in
getting the profit of 5%.
ZK
KK
ZZ ZT KZ KT
TZ
KZ
TK
KT
TZ
Q5
TT
9000
8000
Q4
7000
10000
Q3
8000
Q3
6000
5000
6000
Q [t/d]
Q [t/d]
KK
ZZ ZT
Q5
Q4
Q2
4000
RZ RK RT
Rk
Q1
R k'
1
K CP
0
0
100
200
ZK ZT
KK
Q2
RZ RK RT
2
2000
1.5
x 10
6
Q1
Rk
K CP
1000
0.5
300
400
t [d]
ZZ
4000
3000
2000
10000
ZK
10000
TK
TT
Zp [t]
0
TK
0
0.2
x 10
Q5
K Z K T TZ TT
0
6
0.4
0.6
0.8
TZ TK TT
1
1.2
Zp [t]
Q5
1.4
1.6
1.8
2
x 10
Q4
6
Q3
2
9000
1.8
8000
Q4
1.4
Q3
1.2
Zp [t]
Q [t/d]
6000
5000
4000
Q2
RZ RK RT
3000
Rk
Q1
2000
K CP
1000
0
0
Q2
1.6
7000
1
KZ
KK
KT
Rk
Q1
0.8
0.6
RZ RK RT
0.4
ZZ ZK ZT
0.2
K CP
50
100
150
200
t [d]
250
300
350
400
0
0
50
100
150
200
t [d]
250
300
350
400
No 2A in view of the balance between the costs of coal production and incomes from sales
nr 2A w aspekcie zrównoważonego kosztu pozyskania węgla z przychodami
205
impact of absolutely fixed costs and variable costs is considerably smaller. In comparison with longwall faces No 1A and 1B the impact of absolutely fixed costs is stronger.
This impact is proportional to the quantity of the required daily output corresponding
to a given break-even point.
7000
6000
5000
K CP
RT
4000
3000
2000
KZ
K BS
CZ
RK
1000
RZ
K WS
0
K BS
K WS
KZ
CZ
-1000
-2000
-100
-80
-60
-40
-20
0
20
40
60
80
100
in the values of the parameters for longwall face No 2A
na zmiany wartości analizowanych parametrów dla ściany nr 2A
be decreased by 4% for absolutely fixed costs, by 20% for relatively fixed costs, and by
5.9% of variable costs. On the other hand, an increase of the coal sales price by 20%
daily output by 44%.
Longwall 2B was extracted for about 6 months, during which there were 113 coal
move lasted for 34 months. In that case there was also a break, between the realization of
longwall cut-through to the longwall machinery move, lasted 13 months, which caused
absolutely fixed costs increase.
required daily coal output in the costs balance (Fig. 4.9), indicated that, if the crite-
206
rion of the fixed reserves of the longwall panel is met, the net daily output should be
At the maximal haulage speed of the shearer loader KGS 410 of 6.0 m/min a high
concentration of extraction may be achieved, if the index of work time availability
ψT = 0.5 and the technological efficiency ratio ηt = 0.4.
In consideration of the above data, it may be stated that it would be possible for the
discussed longwall face to get profit, if the technical potential of the machinery was
used better.
To determine the impact of particular costs components of coal production and coal
sales price on the quantity of the daily coal output, which is a prerequisite of economic
efficiency, the sensitivity analysis was conducted.
Z Z Z K Z T K Z K K K T TZ
ZZ ZK ZT
10000
TK TT
K Z K K K T TZ
TK TT
Q5
Q5
9000
8000
Q4
Q3
6000
Q2
4000
0
0
RZ
100 150
Rk
Q1
R k'
200 250
300
350 400
t [d]
0.5
0
RZ
2
1
x 10
6
1000
Zp [t]
TZ TK TT
Rk
Q1
2000
1.5
0
K CP
0
0.2
x 10
Q5
0.4
0.6
0.8
6
1
1.2
Zp [t]
1.4
Q5
Q4
1.6
1.8
2
x 10
6
Q3
2
1.8
Q4
8000
1.4
Q3
5000
4000
RK
3000
Q2
K CP
KZ
0
50
100
KK
Rk
0.8
RT
RK
0.4
ZK
ZT
ZZ
0.2
KT
150
KK
0.6
Rk
Q1
1000
1
RZ
RT
RZ
2000
KT
1.2
Zp [t]
6000
Q2
1.6
7000
Q [t/d]
Q2
RT
9000
0
RK
3000
K CP
50
Q3
5000
4000
RK
RT
ZZ ZK ZT
10000
6000
Q [t/d]
Q [t/d]
8000
2000
Q4
7000
10000
200
t [d]
250
300
350
400
0
0
K CP
50
100
150
200
250
300
350
400
t [d]
207
As shown in Fig. 4.10, like in previous cases, the greatest impact on the daily coal
output is exerted by: the sale price of coal and relatively fixed costs; whereas the impact
of absolutely fixed costs and variable costs is considerably smaller. Like in longwall face
No 2A the impact of absolutely fixed costs is stronger than in faces No 1A and 1B.
7000
6000
5000
RZ
4000
3000
2000
KZ
K BS
CZ
1000
K WS
RK
RT
0
K CP
K BS
K WS
KZ
CZ
-1000
-2000
-100
-80
-60
-40
-20
0
20
40
60
80
100
The case of the longwall faces No 2A and 2B proves that in the longwalls with short
panel lengths gaining economic efficiency is possible. In face No 2A (panel length of
489 m) the daily coal output of 2825 t/d enabled to get profit level of 0.5%. It was due
to the high level of the sale price of coal and no contribution of amortization in relatively
fixed costs.
The sensitivity analysis indicated that for the longwalls with short panel lengths, the
impact of absolutely fixed costs is certainty stronger than for those with extensive panel
lengths, which is caused by a significantly bigger contribution of these costs in the total
costs of coal production. Accordingly, in case of shorter coal field lengths, special attention should be drawn to the costs of the preparatory operations and longwall moves.
Longwall 3B was extracted for about 12 months, including break of one month,
during which there were 2213 coal production days. The total time from the longwall
cut-through to the longwall machinery move lasted for 70 months. The length of the
roadways covering the coal field of longwall faces 3B and 3C is shown in Fig. 4.11.
208
63
-9
VS
m
ise 5 m
Ra - 2 1
3C
No
III
VN
No
No
rift
dd
line
Inc
y No
dwa
Roa
ad
y
wa
m
C
o 3 572
eN t0m
01
fac gh
-1
all l len
S
w
e
IV
ng n
o
Lo ll pa
yN
wa
wa
ng
ad
Lo
Ro
Ro
6m
- 89
e
Rais 48 m
B-2
No 3
Inc
ed
lin
II
oI
tN
drif
Raise 6 m
A - 24
No 3
3B
e No 765 m
ll fac nght gwa
Lon panel le
ll
a
gw
Lon
30 m
- 10
IVN
y No
dwa
a
o
R
3A
e No 950 m
ll fac nght gwa
Lon panel le
ll
gwa
Lon
36 m
- 10
IIIa
y No
dwa
Roa
s
os
Cr
ut
-c
No
III
10
-3
m
Fig. 4.11. Diagram of the coal field covering longwall faces No 3A, 3B and 3C
Rys. 4.11. Schemat pola eksploatacyjnego obejmującego ściany nr 3A, 3B i 3C
As shown in Table 4.1, there were two breaks: one lasted for 11 months, between
the realization of tail and gate roads, and the other from realization of the longwall cutthrough to the longwall machinery move, lasted for 70 months. Thus, the total amount
of absolutely fixed costs was much more higher. The face was located in the distance
from the shaft twice longer than previous analyzed longwalls, what caused some logistic
and organizational problems.
required daily coal output in the costs balance, indicated that (Fig. 4.12), if the criterion of the fixed reserves of the longwall panel is met, the net daily output should be
At the maximal haulage speed of the shearer loader KSE 360 (7.6 m/min) the required daily coal output in the costs balance may be achieved, if the index of work
time availability ψT = 0.7 and the technological efficiency ratio ηt = 0.65. Considering
the fact that, in the long run, the technological efficiency ratio, conditioned by ergonomics, is no more than 0.32 a high concentration of extraction could be reached if the
209
ZZ
Z K Z T TZ
KK
KT
TK
Q5
Q4
KK
KT
TK
Q4
7000
Q3
8000
Q [t/d]
6000
6000
Q2
4000
RT
RZ
200
400
Q1
ZK ZT
1000
0
Rk
RK
6
Zp [t]
0
Q2
RT
RZ
2000
x 10
0.5
300
t [d]
1.5
1
K CP
5000
3000
2
Q1
R k'
100
Q3
4000
Rk
RK
0
0
ZZ
0
0.2
K CP
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
ZZ KZ ZK ZT
KK KT
TK
TT
x 10
Q5
6
K K TZ
KT
2
x 10
Zp [t]
10000
Q5
TT
8000
10000
Q [t/d]
TZ
9000
TT
2000
KZ
10000
KZ
TK Q 5 TT
Q4
6
Q3
2
9000
1.8
8000
Q4
1.4
Q3
1.2
Zp [t]
Q [t/d]
6000
5000
4000
Q2
RT
3000
R
Z
RK
2000
50
KZ
0.8
0.6
Q1
0.4
RT
Q1
ZT
ZK
RK
ZZ
0.2
TZ
0
R k'
1
R k'
1000
0
Q2
1.6
7000
K CP
100
150
200
t [d]
250
RZ
300
350
400
0
0
50
100
K CP
150
200
250
300
350
400
t [d]
coal output contamination and/or the costs of coal production were significantly reduced.
If the production potential of the longwall was used extremely effectively (ψT = 0.7,
v = 3.5 m/min) the coal output could be 2660 t /d, what means that the net daily output
would be Qz = 1900 t /day. Under that conditions the balance between the production
cost and the incomes from sales would be achieved by reduction of relatively fixed
costs by 28%.
Reduction of coal output contamination of at least 50% makes that it would be possible for the discussed longwall face to get the required daily coal output of 2216 t /d and
the balance between the production cost and the incomes from sales was conditioned by
reduction of relatively fixed costs by 19.7%.
210
break-even point.
8000
7000
6000
RZ
5000
4000
K BS
3000
2000
KZ
CZ
RK
RT
1000
K WS
K CP
K BS
K WS
KZ
CZ
0
-1000
-100
-80
-60
-40
-20
0
20
40
60
80
100
Longwall 3C was extracted for about 10 months, during which there were 179 coal
production days. The total time from the longwall cut-through to the longwall machinery move lasted for 39 months. Between realization of the longwall cut-through to the
longwall machinery move there was one long break, lasted for 4 months The face was
located in the same area as the longwall No 3B. Due to the intensive roof fall extraction
have been stopped after the run of 542 m.
The economic model used for designating the break-even points determining the required daily coal output in the costs balance (Fig. 4.14), indicated that, if the criterion of
the fixed reserves of the longwall panel is met, the net daily output should be Qz = 3497
t/day (Table 4.2), which, in consideration of the coal output contamination amounting
to 52%, corresponds to Qz = 5315 t /day.
Thus, a high concentration of the extraction may be achieved, if the index of work time
availability ψT = 0,8 and the technological efficiency ratio ηt = 0,55 (in the case of use
a shearer loader KGS -245, characterised by maximal haulage speed of 6,8 m/min).
211
ZZ ZK ZT
KK KT
TK
TT
Q5
TZ
TZ
KK
KT
TK
TT
8000
10000
Q4
7000
Q3
8000
Q3
Q [t/d]
6000
6000
Q2
4000
Rk
Q1
RK
KZ
100
Q2
3000 R Z
RT
0
0
5000
4000
RZ
2000
R k'
K CP
200
2
1.5
1
400
0
6
0
Q1
RT
1000
Zp [t]
Rk
RK
2000
x 10
0.5
300
t [d]
ZK ZT
K CP
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
ZZ ZK ZT
KK KT
TK
TT
x 10
Q5
6
TZ
TK
TT
Q5
2
x 10
Zp [t]
10000
Q5
9000
Q4
Q [t/d]
ZZ KZ
10000
Q4
6
Q3
2
9000
KT
1.8
Q4
8000
1.4
Q3
1.2
Zp [t]
Q [t/d]
6000
5000
Q2
4000
3000
RT
RZ
1
Rk
0.8
0.6
Rk
2000
Q1
RK
1000
Q1
RT
KZ
ZT
ZK
0.4
0.2
TZ
0
Q2
1.6 K K
7000
0
KZ
50
K CP
100
150
200
t [d]
250
300
350
400
0
RZ
0
50
100
RK
ZZ
K CP
150
200
250
300
350
400
t [d]
No 3C in view of the balance between the costs of coal production and incomes from sales
nr 3C w aspekcie zrównoważonego kosztu pozyskania węgla z przychodami
Considering the fact that due to restrictions caused by ergonomics the production
potential of the longwall was low, a high concentration of extraction could not be reached.
The main problem met at this longwall face was heavy roof fall resulted in high coal
output contamination. Probably this problem could be solved if the setting pressure of
powered roof supports was designed properly. If the potential work time of the machinery
was used extremely effectively (ψT = 0.7) the coal output could be 2229 t /d, at the mean
value of shearer loader haulage speed of 3.5 m/min. Under conditions of achieving the
net daily output of Qz = 1466 t/day the balance between the production cost and the
incomes from sales would be achieved by reduction of relatively fixed costs by 31%.
Reduction of coal output contamination of 50% makes that it would be possible, at the
same level of utilization of technical potential of the machinery, to get the required daily
212
coal output of 1780 t/d and the balance between the production cost and the incomes
from sales was conditioned by reduction of relatively fixed costs by 16.7%.
As shown in Fig. 4.15, for the analyzed longwall face, the greatest impact on the
daily coal output is exerted by: the sale price of coal and relatively fixed costs; whereas
the impact of absolutely fixed costs and variable costs is considerably smaller.
7000
6000
5000
RZ
4000
3000
K BS
2000
KZ
1000
CZ
K WS
RK
RT
0
K CP
K BS
K WS
KZ
CZ
-1000
-2000
-100
-80
-60
-40
-20
0
20
40
60
80
100
in the values of the parameters for longwall face No 3C
na zmiany wartości analizowanych parametrów dla ściany nr 3C
Conversely, the impact of absolutely fixed costs increased for longwalls 1A, 1B, 3B.
5. Conclusions
The results of the analysis of the possibilities of achieving the required daily coal
output in six longwall faces worked in coal mine: “X” indicate that the daily coal output
securing, at least, the state of balance between the production costs and the incomes from
sales is determined by the technical, organizational and economic conditions.
The technical and organizational conditions exert both direct and indirect impacts on
the option of achieving the required daily output. The direct impact involves the production potential of the longwall face and the degree of its utilization, whereas the indirect
one involves shaping the values of relatively fixed costs depending on the extraction
time of the longwall panel with specific coal reserves.
213
The economic conditions determine the required daily output providing, in consideration of specific coal reserves, the balance of the costs. The sine qua non prerequisite
of achieving at least the balance between the costs is such degree of the utilization of
the production potential that could provide the daily coal output determined by the
economic conditions.
As far as longwall faces with extensive panel lengths are concerned, and, correspondingly, long extraction time, where the contribution of relatively fixed costs is the biggest, a higher degree of the utilization of the production potential should be provided,
securing the balance between the costs and the incomes from sales. As far as longwall
faces with short panel lengths and short extraction time are concerned, the contribution
of relatively fixed costs is certainly smaller.
In all analyzed faces, the contribution of relatively fixed costs was the biggest, constituting 65.3%-84.7% of the total costs of coal production.
The second biggest group of costs were variable costs; their contribution in the total
costs of coal production is 7.4%-20.7%.
Absolutely fixed costs had the smallest contribution in the total costs of coal production: from 5.8% to 16.2%. In longwall faces 1A and 1B they were almost twice lower
than in longwalls 2A, 2B and 3C. These costs were mainly related to the panel length.
In case of longwalls 2A and 2B with short coal field length, there was a big contribution
of absolutely fixed costs in the total costs of coal production. Whereas; the longwalls
with extensive panel length were characterized by a low contribution of absolutely fixed
costs (1A, 1B, 3B). Accordingly, to secure the balance between the production costs
and the incomes from sales in longwalls with short panel length, absolutely fixed costs
should be reduced. In case of longwalls with extensive panel length and low percentage
of absolutely fixed costs in the total costs of coal production (1A, 1B, 3B) relatively fixed
costs should be reduced, by, for example, increasing the daily output of coal.
However, the increase of the daily output did not always lead to the achievement of
the balance between the costs and the incomes. Therefore, the sensitivity of the daily
coal output to the change in the costs components and coal sale price was analyzed to
define measures securing the reduction of the total costs of coal production.
The results indicated that the biggest impact on the change of the daily coal output
was exerted by the sale price of coal.
Nevertheless, it is difficult to forecast the sale price of coal at the stage of designing
the longwall panel, as this value does not only depend on the quality of coal or other
management-related decisions, but is determined by external factors.
Another factor that has an essential influence on the daily coal output is relatively
fixed costs. Absolutely fixed costs and variable costs do not exert such strong impact.
The impact of absolutely fixed costs depends, to a certain extent, on the panel length.
The longwall faces with short panel length, for example 2A and 2B, are characterized
by a stronger impact of absolutely fixed costs than longwalls with extensive strips (1A,
1B, 3B).
214
REFERENCES
B r z y c h c z y E., 2006. Metoda modelowania i optymalizacji robót górniczych w kopalni węgla kamiennego z wykorzystaniem sieci stochastycznych. Część 3. Model matematyczny. Gospodarka Surowcami Mineralnymi, t. 22,
z. 3, Kraków.
J a b ł o ń s k a - F i r e k B., 1999. Kierunki strategii działania kopalń w świetle badań modelowych. Zeszyty Naukowe
Politechniki Śląskiej, seria Górnictwo 2000, Gliwice.
J a s z c z u k M., 1999. Wpływ stanu obciążenia kombajnu ścianowego dużej mocy na możliwość uzyskania wysokiej
koncentracji wydobycia. Zeszyty Naukowe Politechniki Śląskiej, seria Górnictwo nr 1406, Gliwice.
J a s z c z u k M., K a n i a J., 2007. Warunki skutecznego i efektywnego wybierania pokładów węgla systemem ścianowym. Prace Naukowe-Monografie, CMG KOMAG, Gliwice.
M a g d a R., 1999. Modelowanie i optymalizacja elementów kopalń. Biblioteka Szkoły Eksploatacji Podziemnej,
Kraków.
M a g d a R., F r a n i k T., D o m a ń s k i J., 1992. Ocena istotności wpływu wybranych czynników techniczno-organizacyjnych na optymalne parametry geometryczne pól ścianowych. Archiwum Górnictwa, t. 37, z. 3, Kraków.
Received: 27 November 2007

Arch. Min. Sci., Vol. 53 (2008), No 2, p. 183–214

Transkrypt

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