SHAFT SINKING excluding shaft stations and loading pocket , is planned to be 3.2 m / d , with the initial sink to 200-m depth at 70 % of this rate . Following sinking and lining , shaft equipping is scheduled to take two months which includes shaft stations and the loading pocket .”
While the prefeasibility study on the Island III expansion assumed one bucket for hoisting rock from the shaft face , Redpath ’ s plan is for two buckets , which will reduce the mucking time , with the double-drum production hoist utilised for this purpose , according to Fitzgerald , adding that the service hoist will be used to install shaft utilities , allowing for more concurrent work .
“ Two slick lines will be used for concrete delivery , located on opposite sides of the shaft , allowing concrete liner placement from two locations concurrently ,” he said . “ Redpath will be using shaft jumbos ( for drilling ) slung from the headframe , rather than nested on the galloway structure , which has provided space for the second bucket and allows ready maintenance of the jumbos in the headframe .”
Redpath will be using its instrumentation and control technology to ensure maximum safety and productivity on the project , which will allow up to four conveyances to work concurrently in the shaft , according to Fitzgerald .
He added : “ While not new to the industry , we have seen significant benefits from having Redpath work with our engineering consulting group and steel supplier / fabricator for headframe design to provide the required functionality for both sinking / equipping and production phases .”
As of August , shaft pre-sink work had commenced , with a plan to kick off actual shaft sinking in the September quarter of 2023 . funds for the project , we were going full steam ahead with procuring long-lead items ,” he said . “ Even though this happened during the COVID pandemic , it didn ’ t delay the project and we are about to go into full sink on both shafts .”
Lucara Diamond Corp , the majority owner of Karowe , confirmed in its June quarter results that the shaft sinking phase had now commenced .
It said pre-sink activities for both the production and ventilation shafts were completed , including placement and erection of headgear for the production shaft . It added that the production shaft stage winder was installed and roped-up , while commencing of the main sinking for the production shaft was expected to take place later in the year .
The sinking project is part of the Karowe UGP , which is expected to extend the mine life to at least 2040 .
Macnab says a copper project in Brazil is currently going through a similar process .
“ The client approached us with a concept for transitioning the mine from open cast to underground that proved to be unsuitable ,” he said . “ We came up with a solution within 10 weeks , developed that to the next phase , and were able to cut off about a year of the cycle of getting the project off the ground simply because we had inhouse designs , costing and schedules that we could draw on from our UMS METS business , saving the client time and money in the feasibility phase .”
UMS has since been appointed to undertake the engineering and procurement for a new
1,500-m-deep shaft at the mine in Brazil .
IM
Front-end engineering capability
Over the last five years , the United Mining Services ( UMS ) Group says it has evolved its operations to combine the capabilities of the UMS METS and UMS Shaft Sinkers businesses , and facilitate a seamless project transition for clients from concept to prefeasibility , feasibility and into execution .
The Karowe Underground Mine Expansion Project in Botswana is a prime example of a client benefitting from UMS ’ front-end capability , according to Murray Macnab , UMS Group Executive Technical Director .
UMS has been contracted to engineer and design the shaft sinking of 750-m-deep production ( 8.5-m-diameter ) and ventilation shafts ( 6-m-diameter ) at the mine .
The client approached UMS with a feasibility study to convert the open-pit mine to underground to extend the mine life to at least 2040 .
“ We did the trade-offs first , followed by the detailed design , and , while the client was raising
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SEPTEMBER 2022 | International Mining 89