Multislice Longwalling for Thick Seam Extraction ... Longwalling for Thick Seam Extraction -...
Transcript of Multislice Longwalling for Thick Seam Extraction ... Longwalling for Thick Seam Extraction -...
Multislice Longwalling for Thick Seam
Extraction - Properties of Goaf in the Roof
and Gate Roads Behaviour
AusRock 2014: Third Australasian Ground Control in Mining Conference
5–6 November 2014, Sydney, Australia
Presenter: Stanisław Prusek Authors: Prusek S.,¹ Lubosik Z¹., Płonka M1., and Syrek B²
¹ Główny Instytut Górnictwa (GIG), Poland ² Katowicki Holding Węglowy SA (KHW), Poland
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 2
PRESENTATION OUTLINE
Some information on Central Mining Institute (GIG).
Some data on Polish hard coal mining industry.
General information concerning Thick Coal Seams Extraction.
Properties of Goaf in the Roof and Gate Roads Behaviour –
underground measurements.
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 3
Some information on Central
Mining Institute (GIG)
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 4
The Central Mining Institute (in Polish: Główny Instytut Górnictwa, in brief: GIG)
Research institute, established 1945,
Subordinates to the Minister of Economy of Poland,
Employees (2013) – 578 people, including 14 professors and 15 Assoc. Prof.,
Notifying Body No. 1453 of the European Union within the range of the
directives:94/9/WE (ATEX),98/37/WE (machinery), 93/15/WE (explosives for the civil use),
and explosion-proof safety according to the world certification system IECEx,
The Scientific Council holds full academic authorizations to grant the degree of
doctor and doctor habil., and to apply for the title of professor in mining (since 1961) and
environmental engineering (since 1998).
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 5
Basic areas of GIG activity
SOCIO-ECONOMIC STUDIES
OCCUPATIONAL SAFETY IN THE INDUSTRY
MATERIAL ENGINEERING
CERTIFICATION, ATTESTATION, INTEGRATED
MANAGEMENT SYSTEMS
MINING AND GEOENGINEERING
ENVIRONMENTAL ENGINNERING
TRAINING AND EDUCATION
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 6
An unique place for mining investigations in a real scale
Experimental Mine „Barbara”
COAL DUST EXPLOSION IN EXPERIMENTAL GALLERY
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 7
Some data on Polish hard coal
mining industry
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 8
Coal is the major fuel used for generating electricity in Poland.
About 86 % of electricity is produced in coal-fired power plants.
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 9
Location of Polish coal basins and coal production in Poland in 2013
Total – 142.3 Mt
Hard coal – 76.5 Mt
Lignite (brown coal) – 65.8 Mt
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 10
Production – 76.5 Mt,
(64.4 Steam coal, 12.1 Coking coal)
Number of underground mines – 30,
Employees – about 107 000 workers,
Extraction system –107 single entry retreat
longwalls were employed, 101 longwalls with
natural roof caving and 6 with hydraulic backfilling
Average extraction depth - 713 m.
Polish hard coal mining industry in 2013
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 11
Gas hazard
Fire hazard
Dust hazard
Seismic and rock burst hazard
Water hazard
Climatic hazard
Radiation hazard
The coal seams are mined in conditions of natural hazards:
Such mining conditions negatively
affect the costs of mining activity
of Polish companies
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 12
General information concerning
Thick Coal Seams Extraction
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 13
Among the methods commonly used for thick coal seams extraction the
following can be mentioned:
Single pass longwall (SPL)
Multi-slice longwall (MSL)
Longwall top coal caving (LTCC).
B.Hebblewhite, Morgantown 2013
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 14
In Poland Multi-slice longwalling (MSL) is employed
the coal seams are extracted in slices with:
roof caving, extraction from top to bottom
(descending order),
hydraulic backfilling, extraction from bottom to top
(ascending order),
combination of the above two systems (hybrid).
Underlying slice is mostly
mined after 2-3 years
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 15
Properties of Goaf in the Roof and
Gate Roads Behaviour –
underground measurements
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 16
IMPREX
PROJECT
Realized
in years
2008-2011
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 17
Multi-slice longwalling in KHW Company
data collected from 24 longwalls
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 18
Average values of coal beam thickness and coal UCS in the longwalls
operated under previously extracted upper slice of the seam
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 19
Underground measurements were carried out in three longwall panels
located in slices of seam 510
Longwall Name 02a seam 510 slice II
04a seam 510 slice I
XVII seam 510 slice II
depth, m 815-865 795-850 700-765
seam inclination, 0 4 4-6 4-6
longwall height (seam thickness), m 3.6 (5.5 – 7.95) 3.0 (6.6 – 7.95) 2.7 (4.0-4.47)
longwall length, m 220 270 140-170
longwall panel length, m 860 610 720
coal beam thickness, m 0.4-0.8 0.4-0.8 0.4
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 20
Scope of underground measurements
Location of measurement stations in longwall panel 02a,
seam 510, slice II
Ø96 mm – borehole
10 m long
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 21
Assessment of the strength parameters of the caving
goaf by means of the borehole hydraulic penetrometer.
Determination of the caving goaf structure by means of
the borehole endoscope (endoscopic methods).
Assessment of the strength parameters and goaf structure - employed devices
Head with
a needle
Hydraulic
pump
Console for measuring and
storing the pressure data
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 22
Results of measurements of goaf compressive strength
The average values of goaf
compressive strength obtained from
the boreholes drilled in :
longwall panel 02a:
test no 1 - 36.53 MPa
test no 2 - 13.17 MPa
test no 3 - 28.2 MPa
longwall panel 04a:
test no 4 - 22.7 MPa
test no 5 - 28.4 MPa
longwall panel XVII:
test no 6 - 4.14 MPa
test no 7 - 24.3 MPa
Example of the strength parameters of the caving goaf measured
by means of the borehole hydraulic penetrometer – longwall 02a
Raise 3’a Raise 4a
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 23
Assessment of the structure of goaf in longwall panels 02a,
04a and XVII performed by means of endoscopic method
In most investigated boreholes the goaf was intensively cracked
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 24
Vertical and horizontal convergence and floor heave in Raises: 3’a, 5a and 19
- values and trend lines
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 25
Load exerted on steel arches in Raises 3’a, 5a and 19
- values and trend lines
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 26
CONCLUSIONS
1. In the Polish hard coal mines in seams to be extracted in slices, i.e. ones with a
thickness of 4.5 m and more there are around 952.6Mt of coal which constitute that
part of the resources which may be economically extracted.
2. The Multi Slice Longwall System (MSLS) is already a commonly used method for thick
seam extraction in Poland.
3. In order to design a longwall under a previously extracted upper slice of the seam it is
necessary to determine the compressive strength of the caving goaf at the roof, its
quality and the load on the support.
4. High variability (from 0 to 80MPa) of the caving goaf compressive strength
assessments obtained by means of a borehole penetrometer led to the conclusion that
the results do not describe the caving goaf parameters but the parameters of rocks,
which form the caving goaf only. Hence the use of a borehole penetrometer to assess
caving goaf UCS is not recommended.
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 27
5. The most promising way to determine the roof conditions in longwalls under a caved
goaf seemed to be an assessment of the equivalent compressive strength and degree
of reconsolidation.
6. All boreholes into the goafs examined by means of the borehole endoscope were
cracked, some of them practically the whole length, but others in some zones only. It
can be concluded that the density of fissures reduces with the distance from the roof to
the gateroad.
7. The results of the gateroad stability measurements confirmed that in the workings
located under the goaf no large convergence or load were observed in comparison with
the workings located below the natural roof .
CONCLUSIONS
DEPARTMENT OF EXTRACTION TECHNOLOGIES AND MINING SUPPORT www.gig.eu 28
Thank you for your attention
Stanisław PRUSEK, Associate Professor
Head of Department of Extraction Technologies and
Mining Support
GIG
plac Gwarków 1
40-166 Katowice
Poland
phone: +48 32 2592423
fax: +48 32 2584425
mobile: +48 512293839