Thinking outside of the box-hole

 Raise drilling seems to be the hot topic at the moment.

What was previously fairly staid technology has leaped ahead all of sudden, with innovation driving it push into areas which have never used the technique previously. 

In particular, there has been a serious shift to underground mining.

One of the newest developments on the block is Mancala’s mechanised vertical miner – the MVM1100.

In underground mines, a large number of short small diameter slot holes need to be excavated, the MVM1100 uses boxhole technology based on field proven pipe jacking methods to fulfill this fairly underserviced area.

Created in conjunction with German tunnelling firm Herrenknecht, the vertical miner was built as “we saw a need for a machine to carry out rises in underground mines which also eliminated the need for a person on site,” Mancala chief executive Martin Kyne told Australian Mining.

Typically, boxhole drilling sees an operator exposed to falling rocks during drilling.

One of the major safety features of this technology is its ability to drill ventilation shafts and ladderways instead of employing blasting methods or blind shaft drilling.

The need for this technology predominately came from Newcrest, for its Cadia gold mine, to help the miner with its block caving mining, with greater focus on safety following the recent Pike River coal mining accident.

Kyne explained that “essentially this technology is just pipejacking for a vertical miner, and from the technology side there is nothing revolutionary about it all, but it is a new application for it.

“You can use a raise bore machine and get similar results, but the mechanised vertical miners are able to do the same job safer and faster (compared to conventional systems), they can set up independently as the machine can tram about while remotely controlled and is able to be detached from the crawlers which typically move boxhole drills around the underground tunnels.”

This is what separates this 37 tonne machine from the pack.

It is able to drill slot hole diameters of up to one metre at lengths of up to 30 metres at inclinations of up to 30 degrees.

According to Mancala, by next year it will increase these capabilities to be to drill diameters of 1.5 metres and lengths of 69 metres.

It has a modular design and the cable and hose reel unit, transport system and power unit can be uncoupled for increased flexibility in compact work sites.

Its jacking frame provides a push force of approximately 2000kN, with its gripping unit stabilising the jacking frame and bracing itself against the roof and floor.

The hydraulic boxhole boring unit has a nominal cutting torque of 40kNm and its cutterhead rotates independently at the top of the drill pipe column, while its rotational speed and torque are adjustable via the control system.

It also features a skip, which allows discharged materials to be more easily handled and disposed.
A phase two model is in the wings and will come with a conveyor system to remove the ore.

The machine has already undergone months of testing at underground tunnels in Germany, and was commissioned last month.

According to Kyne it already meets New South Wales mining design guidelines.

Mancala is also reportedly developing a narrow vein miner.

Where this technology is really set to make an impact in hardrock mining is in its ability to fully tap the ore.

The drill works along the tunnel, drills a hole upwards into ore through to the next tunnel up, this shaft is then filled with paste or cement once the ore is removed.

The unit then leaves a space and repeats the process across the ore body.

Once this is done, and all the hollow vertical shafts have been filled, it comes back and drills into the spaces it previously left.

“It is an extremely precise unit, as the whole aim is to extract the ore with the least amount of dilution possible,” Kyne told Australian Mining.

 

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