https://www.miningweekly.com

Machine reduces shaft-sinking time by 20% to 30%

5th September 2014

By: Chantelle Kotze

  

Font size: - +

Mining contracting company Murray & Roberts Cementation, in partnership with tunnel boring machine manufacturer Herrenknecht and Germany-based Thyssen Schachtbau, has developed the latest-generation rodless shaft-boring machine, known as the shaft-boring enlarger (SBE), which reduces shaft-sinking time by between 20% and 30%, compared with conventional shaft-sinking technology.

The machine became available to the market in June, subsequent to the six months that it took the partners to develop the machine.

The companies embarked on the development of the new generation SBE in January owing to two key factors. The manufacturer of the old- generation machine fell out of the marketplace and there was still a demand for this type of shaft boring machine but, specifically, one that could go beyond the capacity of the older machines and one that was more powerful and could bore larger diameter shafts.

Murray & Roberts Cementation business development executive Allan Widlake explains that the newly developed 350 t SBE machine basically works like a modern hard-rock tunnel-boring machine, but vertically.

He says the choice of this particular sinking method is not limited to a certain depth; however, it is conditional upon having an access drift available at the lowest part of the shaft, as well as sufficient debris clearance capacity for the excavated material.

The sinking of a shaft with the SBE occurs in three phases. Firstly, a pilot hole is created from surface downwards using directional drilling to set the vertical target axis.

Once at the bottom, workers in the drift replace the drill bit with a reamer to enable the enlargement of the pilot hole from bottom to top using the raise boring technique to an advance hole diameter of between 1.8 m and 2.4 m.

Lastly, the SBE enlarges the advance hole to a shaft diameter of between 7.5 m and 9.5 m.

The advantage of shaft sinking using the SBE, compared with conventional shaft sinking method, is that the SBE can bore, support and line the shaft simultaneously, without any stoppages.

While there are many parameters that influence the time it takes to sink a shaft using an SBE, the machine enables significantly higher sinking speeds at an average advance rate between 6 m and 10 m a day, which includes the supporting and lining of the shaft.

The high precision in terms of the vertical and circular shape of the shaft cross-section and the virtually vibration-free ground treatment are further advantages of shaft boring using a SBE machine.

This concept of enlarging an advance hole using rodless shaft boring technology, which was established in the market as V-mole technology, has been around since the early 1970s as patented by Thyssen Schachtbau.

Since then, Thyssen Schachtbau has been involved in sinking over 50 V-mole shaft boring projects with a cumulative depth of 20 km and finished diameters varying between 5 m and 8.2 m.

The world’s deepest surface shaft to be sunk using the V-mole system is the Primsmulde shaft, at Ensdorf colliery, in Germany, owned by German coal mining corporation RAG AG, formerly Ruhrkohle. The shaft was sunk between 2001 and 2012 and has a final depth of 1 260 m and a diameter of 7.8 m.

In South Africa, there have been two such shafts bored to date. These are the subvertical ventilation shaft at Gold Fields’ South Deep mine, on the West Rand, and a ventilation shaft at gold miner Sibanye Gold’s Beatrix West Section, previously the Oryx mine, in the Free State.

The SBE is ideal for the sinking of ventilation shafts in brownfield mining operations with existing bottom access but can also be used to sink mine production shafts.

Widlake tells Mining Weekly that it is currently in talks with several local clients that have long-term plans for establishing new shafts, which “we believe will provided us with contract opportunities in the next few years”.

Edited by Martin Zhuwakinyu
Creamer Media Senior Deputy Editor

Comments

The content you are trying to access is only available to subscribers.

If you are already a subscriber, you can Login Here.

If you are not a subscriber, you can subscribe now, by selecting one of the below options.

For more information or assistance, please contact us at subscriptions@creamermedia.co.za.

Option 1 (equivalent of R125 a month):

Receive a weekly copy of Creamer Media's Engineering News & Mining Weekly magazine
(print copy for those in South Africa and e-magazine for those outside of South Africa)
Receive daily email newsletters
Access to full search results
Access archive of magazine back copies
Access to Projects in Progress
Access to ONE Research Report of your choice in PDF format

Option 2 (equivalent of R375 a month):

All benefits from Option 1
PLUS
Access to Creamer Media's Research Channel Africa for ALL Research Reports, in PDF format, on various industrial and mining sectors including Electricity; Water; Energy Transition; Hydrogen; Roads, Rail and Ports; Coal; Gold; Platinum; Battery Metals; etc.

Already a subscriber?

Forgotten your password?

MAGAZINE & ONLINE

SUBSCRIBE

RESEARCH CHANNEL AFRICA

SUBSCRIBE

CORPORATE PACKAGES

CLICK FOR A QUOTATION