VERTICAL DEVELOPMENT

Mechanised Slot Rising

Mining operations frequently require a slot or box hole within stoping blocks to provide void space for subsequent blasting operations. Traditionally these have been excavated by either the inherently high risk hand held method; the moderate risk, high consequence long hole blasting method or the low risk although time consuming method of box hole raise boring.

To address the shortcomings of the traditional methods, Mancala in conjunction with Herrenknecht of Germany has developed the Vertical Miner. The  is a self propelled, electrically powered (Jumbo Box connection) machine designed to quickly and safely bore vertical to -60 degree, 1.1m diameter blind up-holes to 35m in length. Based upon proven pipe jacking technology, the MVM has 950kN of thrust and 48kNm of torque enabling it to bore through most rock formations.

At its recent commissioning at Newcrest's Cadia mine, the MVM has bored over 650m achieving the boring cycle of rig up, bore and rig down in 30 hours for an 18m hole. With productivity a KPI within the MVM's design, the machine uses standard mine services, does not need a concrete pad and is self contained. Tram to site (3kph), bore a hole and tram away. Operator safety is inherent in the MVM with the operator stationed remotely from the machine, drill pipe stationary (head alone rotates) and spoil is directed internally within the thrust pipes to a collection bin.

With an operational capability of 30m, the MVM can be used to excavate mine infrastructure, including escape rises and ventiliation shafts.  Further applications for the MVM beyond box hole boring include narrow vein mining of high value ore.

Conventional Raise Bore

In 1994 Mancala commenced raise boring in the Australian market as an adjunct to its shaft construction techniques of Horadiam and Bench and Line.

These methods of shaft construction each require a small diameter pilot shaft, upon which the larger shaft is constructed. At the turn of the 21st century, Mancala recognised a need in the Australian market for a professional, innovative and above all else safe raise boring contractor.  Subsequently, Mancala's raise boring business unit has grown to encompass eight rigs with capabilities to ream holes from 200mm to 5.5m in diameter and nominally 600m in length.

Site based operations are supported by a comprehensive management system which aims to provide the safest, most reliable and productive raise boing service in Australia and the Australasian region.

Our current raise bore fleet consists of:

Collars and Liners

With over 20 years' experience in shaft construction and ancillary activities, Mancala is able to provide its clients with:

• Geotechnical appraisal of the proposed shaft site;
• Design and construction of surface infrastructure which can combine the requirements of both the raise boring activity and the final shaft use (e.g. fan, evasse or GAG installations);
• Pre or post sinking in near surface lithologies using a variety of methods and
• Non-entry shaft support using either sprayed fibrecrete or steel liners.

Over recent years Mancala has seen an increasing requirement for shaft support which incorporates speed of installation, structural certification and flexibility. As a consequence Mancala has adapted and improved the process of using galvanised steel liners as a non-entry method of ground control for vertical raise bored shafts.

The concept uses modular liner segments which are assembled as the installation is lowered into the shaft immediately following the raise boring activity.  The method which can incorporate grouting of the shaft/liner annulus has been used on shafts up to 5.5m in diameter and in excess of 320m depth with the total liner segments weigh over 240 tonnes.   

Off site fabrication and on site assembly during raise boring allows installation rates of up to 40 metres per day.  Adaption of the liner design to incorporate ladderways for second egress or service lines are available.

Flame Proof System for Raise Bore Underground Coal

Mancala has recently developed a fully certified and compliant raise bore power pack for use in Australian underground coal mines.  The power pack is designed for use in conjunction with all of Mancala's small to medium size raise bore rigs and is certified to:

• MDG 1010
• MDG 15
• MDG 35.1
• MDG 1030
• MDG41

The power pack features:

• Remote control via an operator pod
• Quick Detach System, fork tynes, lifting lugs and skid base to provide mobility options
• 110% capacity incorporated oil bund
• Australian Standards electrical compliance of 3000, 60079, 1299 and 1972

Bore Hole Hoisting

The low capital cost, rapid deployment and simple operation of the BHH system can minimise the requirement for underground haulage capacity in situations where existing infrastructure is distant to mining areas. For long strike ore bodies, the BHH system can be installed at predetermined locations along strike, providing hoisting capacity and services access to underground.

Capacities

The BHH system has been used at the Glennies Creek Colliery in NSW to hoist shaft construction waste rock from 330m depth at a rate of 450 tonnes/day (160k tpa).

The scalability and flexibility of the system allow cost effective haulage capacities to 350k tpa using a 6 tonne capacity conveyance, 2.44m diameter raise bore hole and to depths of 650m.

SHAFT SINKING 

Mancala traditional shaft sinking capabilities have been utilised in numerous applications including:

• Pre sinks in areas of poor ground conditions prior to full shaft excavation by other methods
• Underground coal storage silos
• Complete shaft excavation up to 6.0m diameter and 250m depth - concrete or fibrecrete lining
• Ore pass refurbishment and lining by shrinking

The Future Developments:

• Non-entry 14m diameter to 500m depth
• Mancala in conjunction with Herrenknecht is developing methodologies to reliably sink and concrete line shafts at productivities which far exceed existing technologies 

SHAFT REHABILITATION

Using either Mancala's mobile head frames and winders or client's existing infrastructure, Mancala can safely and efficiently repair high value mine assets.  Mancala has decades of experience in shaft refurbishment and maintains a core of highly experienced shaft miners for such tasks.

With Mancala's infrastructure, we can refurbish any shaft configuration from 2.4m diameter to 5.0m and up to 500m depth.Notable achievements in the area was the Beaconsfield mines, Hart Shaft refurbishment which involved 400m of refurbishment and re-equipping while de-watering up to 800 litres per second.  More recently Mancala was contracted to remove or replace 200m of shaft furniture in the Vatukoula Gold Mine's Philip Shaft.  All work was undertaken while the shaft was in operation with no incidents or disruption to production.

Vertical Development

HORADIAM EXCAVATION

Mancala's method of progressive shaft opening via raise boring and Horadiam techniques can be used in the excavation of new shafts and for construction of large underground coal bins.

Mancala's Horadiam method offers a significant increase in productivity compared to traditional sinking methods.

Construction can take place in relatively poor rock masses where large diameter raise boring would be considered high risk.The progressive shaft opening technique allows the inherent geotechnical risk in shaft construction to be effectively managed.At each stage of the shaft's construction the geotechnical characteristics of the rock mass can be assessed and appropriate ground support regimes can be installed.

Horadiam construction of large diameter shafts incorporate:

Minimised Risk

• Technical and commercial risk can be minimised via continuous assessment of the geotechnical environment.Permanent ground support can be installed beyond the shaft's final diameter prior to excavation. 

Fast and Efficient

• At Lenstier where traditional raise boring methods failed, Mancala enlarged a 2.4m diameter shaft of 200m length to 5.5m in less than 9 weeks on site.
• The productivity, efficiency and flexibility of Horadiam place it as one of the most cost effective methods of shaft construction.
• The top down temporary support and Horadiam drilling followed by blasting from the bottom up ensures men are working at all times under fully inspected and supported ground.
• Shaft centre line accuracy of 0.01% of the shaft length can be achieved using a directionally drilled pilot hole.During refurbishment or enlargement shafts can effectively be straightened by varying the Horadiam blast hole lengths.
• Mancala has excavated over 3.0km of shafts up to 6.0m diameter using the Horadiam technique. Clients have opted for fibrecrete or concrete lining incorporating various water control devices.

EGRESS SYSTEM

Mancala introduced the concept of suspended modular ladder ways to the Australian market in 1994. In the following years Mancala has designed and installed more than 5.0km of service escape ladder ways in the civil and metaliferous mining industries. Ladders have been installed from both surface and underground locations, in vertical and inclined shafts with completed lengths exceeding 300m.

When combined with our other services, Mancala can offer clients the complete ladder way service comprising:

• Design
• Certification
• Fabrication
• Raise boring
• Installation
• Shaft ground support

In situations where a mechanised egress system is required, Mancala can design, fabricate and install winder and Alimak based systems.