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Curragh Colliery-Coal Mine

Australia / Queensland / Blackwater /
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CURRAGH MINING

One of Australia’s largest independent coal producersCurragh Mine is operated by Wesfarmers Curragh Pty Ltd and covers an area of approximately 12,600 hectares in the coal-rich Bowen Basin of Central Queensland - 14 kilometres north-west of Blackwater and approximately 200 kilometres west of Rockhampton. The mine includes the Curragh Mine, Frasers Mine, New Mammoth Mine, and Mount Morgan Shaft Mine. Mount Morgan Shaft is the southern most pit, and New Mammoth is directly north of that.

One of Australia’s largest independent coal producers, Curragh currently produces 6.5 million tonnes of export coal and 2.5 million tonnes of domestic coal per year.

Open cut reserves at Curragh allow production levels to be maintained to at least 2025, sustaining an efficient mining operation whilst providing a reliable supply for customers and an acceptable return on our shareholders’ investments.


OPERATIONS

MaintenenceCurragh recognises the importance of reliable and efficient machinery to ensure continued coal supply to meet our customer requirements.

Curragh’s maintenance team ensures mine equipment remains in an operational condition to meet mining requirements and that mine infrastructure is operational.

Curragh employees, with assistance from contract resources, are responsible for maintaining all mine equipment, which includes the dragline fleet, overburden drills, coal haulers, rear dump trucks, loading units, dozers, graders and ancillary equipment, as well as all mine electrical and fixed infrastructure.


MiningMining at Curragh takes place on the Aries, Castor, Pollux and Pisces seams within the Rangal Coal Measures of Queensland’s Bowen Basin. The geology is comparatively complex with some significant faulting and variation of seam thickness across the deposit.

The average seam thickness is 2.5 metres for the Aries seam, 1.8 metres for the Castor seam, 2.8 metres for the Pollux seam and 1.8 metres for the Pisces seam.

Detailed mine planning assisted by a highly sophisticated coal preparation plant ensures that saleable products meet the specifications required by Curragh’s customers.

Developed over a strike length of approximately 27 kilometres, mining at Curragh commenced at the line of oxidation and has progressed down dip to the east. The topography also slopes towards the east, limiting the increase in prime strip ratio.

Mining begins with removal of vegetation and stockpiling of topsoil for use in rehabilitating previously mined areas. Overburden above the coal seam is generally drilled, charged with explosives and blasted. Draglines then remove the overburden to expose the Aries seam. In areas where the depth of the Aries seam exceeds the dig depth capability of the dragline, or the presence of loose alluvium precludes blasthole drilling, pre-strip operations are employed. Pre-strip is carried out using a dragline or a truck and shovel operations.

Curragh Mine has four Marion electric draglines for overburden removal including one of the world’s largest—a Marion 8750 Super, with a 114m3 bucket. The draglines operate a multi-pass digging method. Strip widths are nominally 60 metres with the design highwall angle in most areas at 63°.

A fifth dragline—a P&H 2355—provides operational flexibility by performing smaller scale tasks more efficiently than truck and shovel operations.

Exposed seams are accessed by operating low wall ramps with coal mined by hydraulic excavator or front-end loader into 240 tonne capacity bottom dump coal haulers and 200 tonne capacity rear dumps, which transport the coal to the Coal Handling and Preparation Plant for crushing and processing.

After the upper seams (Aries and Castor) are removed, the interburden to the Pollux seam is drilled and blasted. Operating from the low wall on the spoil pile, the dragline then exposes the Pollux and Pisces seams for mining.

In December 2004, mining operations utilising contractors commenced pre-strip operations at Curragh North. Burden is removed by both dragline and contracted excavator and truck operations. In May 2006, M8200 Dragline 301 was relocated from Curragh to Curragh North for burden removal. In September 2007, Dragline 301 was joined at Curragh North by M8750 Super Dragline 304. Dragline burden removal will continue to be supplemented by truck and shovel pre-strip fleets with excavators and trucks used to mine the coal. Coal is transported to the Coal Handling and Preparation Plant on an overland conveyor system for processing.


ProcessingThe Coal Handling and Preparation Plant (CHPP) has been designed from extensive studies into the Curragh coal characteristics to achieve optimal coal quality and maximum coal recovery.

All sections of the plant have been designed to be highly efficient, with simultaneous production of two product streams, and effective blending of both feed and product coals.

The raw coal handling system consists of two main areas: the Curragh Run of Mine (ROM) system and the Curragh North ROM system.

The Curragh ROM system is a dual line design capable of crushing 1,200 tonnes per hour through each line (total 2,400 tonnes per hour). It also allows versatility by running coal to Preparation Plant feed stockpiles through one line and running bypass steam coal through another.

Curragh ROM coal is dumped by 240 tonne haul trucks into 500 tonne capacity hoppers. Variable speed apron feeders discharge coal into hammer-mills reducing coal lump to less than 400 millimetres.

Rotary breakers further reduce coal to a maximum size of 63 millimetres and from this point coal can either be sent directly as bypass coal to the secondary product coal line, or alternately, further crushed by double roll crushers to a maximum size of 32 millimetres and stacked as Preparation Plant feed. Plant feed is stacked in chevron piles to ensure consistent feed for the Preparation Plant.

The Curragh North ROM system is a single line system capable of crushing up to 2500 tonnes per hour. ROM coal is delivered by 190 tonne rear dump trucks or front end loaders to a 600t hopper. The coal is fed from the hopper via a chain feeder into a primary crusher. From the primary crusher, the coal is passed through a secondary crushing system to achieve a maximum lump size of 32mm.

The coal is then transported via the ‘World’s Longest Single Flight Conventional Conveyor’ at 20.02 kilometres in length and a top speed of 27km/hr to a 500 tonne bin at the Coal Handling and Preparation Plant feed stockpile area. From the 500 tonne bin, coal can be directly fed into the CHPP for processing, stockpiled to the Preparation Plant feed stockpiles or bypassed onto a secondary coal product pile.

Reclamation of plant feed from the Preparation Plant feed stockpiles is via two bridge reclaimers. Surge capacity, to provide consistent feed rate to the plant, is provided by two 250 tonne surge bins fitted with electro-magnetic vibratory feeders providing precise feed rate control.

The raw coal stackers and reclaimers are designed and utilised to ensure consistency in the quality and size distribution of the plant feed, prior to processing in the Preparation Plant.

Independently or simultaneously processing two different coal types, the plant handles up to a maximum of 1,750 tonnes of coal per hour through two modules.

On entering the plant the raw coal is screened into two size fractions. Producing both coking and steam coal, the coarse coal (+0.5 mm) is processed in a two-stage dense medium cyclone circuit with the fine coal (-0.5 mm) processed in a single stage froth flotation circuit. Recent upgrades in 2002 and 2004 have seen the introduction of modern coal processing technology into the Curragh CHPP. This technology includes the installation of two Horizontal Belt Filters, Jameson Flotation Cells, 1000mm large diameter dense medium cyclones, VM1500 coarse coal centrifuges, banana screens and dry distributors.

A computerised system using programmable logic controllers (PLCs) manages the operation of each item of equipment in the plant, controls the operation of density control systems, flow rates and feed rates, and protects equipment. In 2004, Quantum PLCs were installed to replace the outdated Modicon units. This provides the CHPP with newer technology and a more reliable and flexible operation.

Coal is stacked on two product stockpiles each capable of holding 150,000 tonnes of product. The travelling luffing stackers produce fully blended stockpiles resulting in all trains being dispatched with coal of consistent quality.

A Bucketwheel Reclaimer loads trains at a rate of around 3,600 tonnes per hour. Dependant on coal type, product is loaded into separate steam or coking coal train load out bins prior to being loaded onto 7,000 tonne trains bound for the Port of Gladstone. The separate train load out bins eliminate contamination between products.


Reference for information:
www.curragh.com.au/

www.curragh.com.au/operations/

Reference for location: bonzle.com/c/a?a=p&p=264394&c=3&x=148%2E856512348252&y=...
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Coordinates:   23°28'20"S   148°52'32"E
This article was last modified 7 years ago