B
HP Billiton chief inancial oicer
PeterBeaventoldananalysts’
conference call recently that the
company could do even more to
improve the productivity of longwalls in the
future.
“Ithinkoneofthelesswellknownfactsis
thestrengthofourseamsandthefactthat
we’veactuallygottopcoalcavingworkingat
Broadmeadow,” he said.
“In fact, that longwall was the most
productive longwall in Australia this last
period.
“And that does give us opportunities to
deploy that technology in further parts of
ourresourcebase,whicharenotactually
replicable, because we’re one of the very
fewthathastheheightofseamsthatwe’ve
got. So, yes, that’s deinitely something we’re
looking at.”
BHP Billiton CEO Andrew Mackenzie said
he had been on-site at Broadmeadow and
saw the longwall in operation.
Broadmeadow uses the southern pits of
Goonyella Riverside Mine for access.
It started longwall operations in 2005 and
transitioned to longwall top coal caving in
2013 in longwall #8.
It is currently mining longwall #12.
Broadmeadow’s roadways mined at 5.6m
wide and 3.7m high and longwall blocks are
320m wide and 3.2km long.
Coal seam thickness ranges from 6.2m to
6.9mandthecuthorizonisthebasal3.9mof
the seam.
Methaneisthepredominantseamgaswith
various gas drainage methods utilised.
he longwall is supported by two
continuous miners and the mine supplies
coal to the neighbouring Goonyella Riverside
mine’s washplant.
Broadmeadow’s superintendent of
longwall production Matt Jones told the
recent Longwall 2017 conference in New
SouthWales’HunterValleythatthemines
maingate design was unique to the longwall
topcoalcavinglongwall.
“heramphasamuchsteeperanglethan
conventional armoured face conveyors,”
he said.
“hepullfromMGsprocketisnotas
direct.
“Pressure angles wear rapidly.”
Jonessaidtherewereafewchallengeswith
the Broadmeadow LTCC.
he shearer loadout is in front of ramp
and bulldozing material gathers in front of
the drive causing additional carryback.
Jones said the shearer was itted with
an Octans IXSEA optical gyroscope that
measuredpitch,rollandyawwithahigh
degree of accuracy.
“heshearerisalsoittedwithranging
arm potentiometers with an accuracy of
25mm over 4000mm range,” he said.
“Itishighlyrepeatableandreliableandhas
low hysteresis and a robust design.”
Initially, the operational personnel had
very limited knowledge of LTCC process,
according to Jones.
“Many design issues were exacerbated or
created by lack of operational knowledge,”
he said.
“Manual operations are very complex
in LTCC. Training and communication of
learnings between all crews was challenging.
“Automation has been the key to
consistency and operational success.”
Dailyreviewmeetingsareheldto“ind
and ix”.
“Practical problem solving investigation
are completed for all delays over four hours.”Convergence
Broadmeadow managed to recover from
the impact of a convergence incident at its
longwall top coal caving mine in Queensland
in late 2015 to continue to ramp up its
production proile in 2016. A BHP Billliton
Mitsubishi Alliance spokeswoman told
Australia’s Mining Monthly:“he structural
integrity of the longwall remains intact.
“he deinition we are using is ‘convergence’
–whichistheresultofstrataabovetheroofof
the longwall shiting and causing the roof to
exert pressure on some of the longwall shields
and impact a part of the longwall face.
“here was no emergency evacuation,
operational procedures worked efectively,
theareaatriskwassecuredsafely.”
Alargeisolatedsandstoneblockformed
and rotated ater 68m retreat. Approximately
680mm of convergence occurred in one
hour, 900mm ater 12 hours.
Jones said hoses and couplings were
damaged, valve blocks split and canopies and
lemniscates cracked. High pressure water
was used over shields to gain height.
he mine ran a secondary bypass
hydraulic system and conducted two weeks
of repairs once height was regained.
BMA Asset President Rag Udd said BMA’s
team onsite at Broadmeadow had done a
“very safe and professional job in managing
therecoveryofthelongwall”.
“he demonstration of passion, innovation
andawillingnesstostepuptosafelyresolve
this issue has been very impressive.
“I also want to thank the other parts
of the BMA business and others across
the underground mining sector for the
assistance we received.”
Uddsaidthelongwallresumedfull
production within weeks of the incident.Broadmeadow’s
LTCC future
BHP Billiton sees the potential for more expansion in Queensland’s Bowen
Basin and is keen to continue the improvements in longwall top coal caving
at its Broadmeadow mine. By Lou Caruana
http://www.miningmonthly.com December 2017 AMM 25
internationalcoalnews.com