SHAFT SINKING
Shaft sinking operations at 9600L elevation – Kidd Mine D Shaft now part of Glencore Kidd Operations in Timmins , Ontario
Integral infrastructure
With the post-COVID-19 commodity price revival up and running , greenfield and brownfield developments are back on the agenda . Dan Gleeson looks at some of the shaft sinking projects and contractors set to unlock this new growth
COVID-19 has affected every part of the mining process ; from logistics to mineral processing , to drilling and blasting and exploration , to human resources and catering .
The shaft sinking sector has not been spared – it is hard to abide by social distance requirements at the bottom of a mine shaft without it affecting productivity – yet , it has fared better than some mining developments , with the majority of shaft sinking projects continuing throughout the pandemic .
Eric Kohtakangas , Executive VP of Growth & Acquisitions for Cementation Canada , explained why this might be : “ Given that shafts often fulfil a vital ventilation function beyond access or material handling , it could be assumed that shafts would remain high in clients ’ priority of their portfolio of planned works , especially for mine expansions and approved greenfield sites ,” he said .
This has certainly been the case at some highprofile projects such as the Turquoise Ridge Third Shaft in Nevada , USA , the Macassa # 4 Shaft project in Ontario , Canada and the Nezhinsky potash project in Belarus ( more later ).
Surprisingly , all three of these projects have remained within or ahead of schedule despite the pandemic headwinds .
The third shaft at Turquoise Ridge , a mine
owned 61.5 % by Barrick and 38.5 % by Newmont within the Nevada Gold Mines joint venture , was
recently sunk to its final depth of 989 m below the collar in June .
Barrick said in its June quarter results :
“ Construction of the Third Shaft at Turquoise Ridge , which has a hoisting capacity of 5,500 t / d , continues to advance according to schedule and within budget . We continue to expect commissioning in late 2022 .”
Together with increased hoisting capacity , the development of the Third Shaft , steered by Thyssen Mining , is expected to provide additional ventilation for underground mining operations as well as shorter material haulage distances .
The focus of the project is now shifting from sinking activities to equipping , with fabrication of the shaft and loading pocket steel underway , as well as other early procurement items necessary to complete the construction of the project .
At Macassa , the # 4 Shaft project remained over a month ahead of schedule at the end of the June quarter , and was on track for completion in late 2022 .
This shaft , engineered by Cementation Canada but sunk in-house by Kirkland Lake Gold crews , could lead to production at the highgrade gold mine growing to over 400,000 oz / y at significantly improved unit costs , according to Kirkland Lake . In addition , working conditions will be improved at the mine , with total ventilation capacity expected to more than double . Future exploration activities could also be positively impacted .
Both examples prove Kohtakangas ’ point , while highlighting just how skilled these shaft sinking specialists are .
A double-edged sword
Jochen Greinacher , Managing Director of Redpath Deilmann , is aware of such skill , referring to the team that sunk the shafts at the Nezhinsky mine , in Lyuban , Belarus , as “ exceptional ”.
This team , aided by the second generation of Herrenknecht ’ s Shaft Boring Roadheader ( SBR ), broke a company record dating back to 1938 , which , itself , was achieved at a time when safety was far from the main consideration on shaft sinking projects .
The Nezhinsky team , in contrast , completed the whole sink and equipping of both shafts ahead of schedule with a Herrenknecht SBR while registering just one reportable accident ( finger injury ).
The use of the SBR , which allowed simultaneous excavating and lining without exposure to the shaft bottom in many sections of the Nezhinsky sinking project , undoubtedly played a role , but the team controlling that machine had to battle weak rock , water ingress
106 International Mining | SEPTEMBER 2021