Tag Archives: Shaft sinking

Herrenknecht heralds ‘game changer for shaft sinking in soft and medium-hard rock’

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Having successfully excavated two 8-11 m diameter blind shafts using Shaft Boring Roadheaders (SBRs) at the BHP-owned Jansen potash project, Herrenknecht is leveraging all the lessons it learnt in Saskatchewan, Canada, to ensure this technology proves to be a “game changer” for the sinking of shafts in soft and medium-hard rock.

Mining contractor DMC Mining Services used two SBRs to excavate the blind shafts at Jansen, with the successful project completion acting as proof of the feasibility and advantages of the Herrenknecht SBR concept for the mining industry, according to the Germany-based company.

In August 2018, the mining industry milestone was achieved with the successful completion of two blind shafts to depths of -975 and -1,005 m, respectively, at the Jansen potash project. For the first time, shafts in the mining business were sunk using only mechanical excavation for this reference project.

Two Herrenknecht SBRs excavated the ground by a partial-face cutting method, using a cutting drum mounted on a telescopic boom. The excavated rock was then conveyed from the bench by an innovative pneumatic mucking system (PNM) and transferred into muck buckets to be hoisted to surface, the company said.

An innovative laser navigation system designed by the Herrenknecht subsidiary, VMT Group, using target units mounted on the SBR and lasers connected to the shaft wall, was used to keep the machines on track.

Herrenknecht, with its experience as a technology leader in mechanised tunnelling, developed the SBR for the mechanised sinking of blind shafts in soft to medium-hard rock. Based on the proven technology of the Herrenknecht Vertical Shaft Sinking Machine (VSM), the SBR offers improved safety performance compared with conventional shaft sinking methods while also achieving higher advance rates, according to the company.

The geological conditions at Jansen, however, were anything but easy. At a depth of around 450 m, the SBR encountered a layer of extremely hard competent rock causing excessive pick wear and low rates of advance. To overcome this and some further hardness challenges, the cutting drum was upgraded to a hard-rock cutting drum and torque output was doubled.

Because an existing high-pressure underground waterway, known as the Blairmore aquifer, posed a risk for water ingress into the shaft, ground freezing was executed temporarily in 2011 by BHP to a depth of approximately 650 m.

A major success in this difficult geology was the use of a mechanical ring erector, which allowed the installation of steel tubbing segments with minimal risk to personnel and a high degree of accuracy, according to Herrenknecht. The steel liner rings were installed through the Blairmore aquifer to assist in the development of a composite steel and concrete watertight liner in both shafts.

Since the project-specific design changes at Jansen required modifications to the SBRs, Herrenknecht, together with contractor DMC Mining Services, refined the SBR technology over the long term. The result is the second generation of Herrenknecht SBR technology.

As an example, the second generation SBR is equipped with an additional stabilisation level that allows the fixation of the SBR centre pipe on both ends. This ensures a stable transfer of the reaction forces from the cutting process to the shaft wall without movement of the machine – even with fluctuating excavation diameter of 8-11 m, as encountered at the Jansen potash project.

In addition to an improved filter system, a new design of the PNM system was installed in the second-generation machine, which results in a higher degree of separation in the suction tank itself, allowing wet material and even water to be handled.

Martin-Devid Herrenknecht, General Manager Mining at Herrenknecht, said: “The technical development of the second SBR generation is based on the lessons learnt from the Jansen project.” Two SBRs of this generation are currently in operation in Belarus and achieving good performance as a result of the improvements made, Herrenknecht said. “This pioneering approach is certainly a game changer for shaft sinking in soft and medium-hard rock, impacting the whole mining industry,” he said.

After the successful excavation at Jansen, another task was to be managed: the disassembly of the huge machines in the deep shafts. To remove the SBR from the shaft bottom, it was necessary to reduce the weight of the machine from 390 t to 340 t. This was achieved by stripping all components off the SBR that were in the excavation chamber. Both SBRs were safely extracted from the two shafts at the Jansen potash project in May 2019.

The Jansen potash project, located approximately 140 km east of Saskatoon, Saskatchewan, is a BHP-owned future potential potash mine with an expected initial mining output of around 3-4.5 Mt/y with valuable expansion options.

Agnico continuing to innovate at Kittilä gold mine as shaft project progresses

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Agnico Eagle is likely to leverage more innovation at its Kittilä gold mine in northern Finland judging by André van Wageningen’s presentation at the FEM conference in Levi, this week.

In a talk titled, Building future mines through collaboration, van Wageningen, Engineering Manager of the Shaft project at Agnico Eagle Finland, said the company was testing out battery-electric equipment and could potentially apply LTE in the underground mine next year.

Much of the battery-electric machine testing the company is carrying out at the mine is in partnership with the EU-funded SIMS project, but van Wageningen said the company has also acquired two electric bolters outside of the program.

As recently as last week, Agnico tested out an Epiroc MT42 Minetruck and ST14 Scooptram at the mine (pictured), with van Wageningen saying the trials had, so far, gone well, with operators noticing less heat generation and vibrations, and better air quality within the operating environment.

“The battery capacity is of course the main concern,” he said in answer to an audience question about how the electrified equipment had so far performed. “Our mine is designed to drive up and…[the machines] have a limited capacity for [that].”

On the topic of collaboration, van Wageningen mentioned that if Agnico had decided on the use of battery-electric and electrified equipment four or five years ago, it would have likely deepened the shaft further and redesigned the mine to suit the reduced ventilation needs and required battery charging/changeout infrastructure.

“If you go for electrification, you either do it or you don’t as you have to build charging stations for this,” he said, adding that these need to be plotted around the mine in relevant locations to ensure the machines are as productive as possible.

As it stands, the company plans to go down to 1,040 m below surface as part of an expansion plan at the mine to increase production by 25% to 2 Mt/y of ore. This could see Kittilä add 50,000-70,000 oz/y of gold to its profile.

The company is building the 5.6 m diameter shaft by, first, raiseboring to 4 m diameter and then slashing to 5.6 m, van Wageningen said. The company is then concrete casting the shaft.

van Wageningen said Agnico has raisebored down to 875 m, and the 94 m headframe was likely to be finalised in the very near future.

The deepening of Kittilä and the evolution towards using autonomous underground machinery is probably behind the company’s plans to leverage LTE communications at the operation.

Agnico is already a leader when it comes to LTE, having become the first company to roll out the communications technology at an underground mine – the La Ronde Zone 5 operation in Quebec, Canada. This move was predicated on Agnico trialling autonomous equipment underground at the mine. In its June quarte results, the company said results from these trials had produced “favourable” results.

BHP’s Jansen potash project set for early-2021 investment decision

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While uncertainty remains around the construction of BHP’s Jansen potash project in Saskatchewan, Canada, the company, in its September quarter results, confirmed it is still spending money on the asset prior to making a development decision.

BHP said the Jansen Stage 1 potash project will be presented to the board for a final investment decision by February 2021. The currently Stage 1 plan, which is in the feasibility study stage, involves building out initial capacity of 4.3-4.5 Mt/y of potash, with expansion optionality.

The miner has, so far, committed to spending $2.7 billion on the project. This is expected to result in the excavation and lining of the 7.3 m diameter production (975 m deep) and service (1,005 m deep, pictured) shafts – sunk by DMC Mining using Herrenknecht’s Shaft Boring Roadheader – and the installation of essential surface infrastructure and utilities. The overall Stage 1 project is expected to have a capital outlay of $5.3-5.7 billion.

In the September quarter results, BHP said in order to make a final investment decision, work on engineering to support project planning and on finalising the port solution is required. The BHP Board has, as a result, approved $144 million of spending for these activities, with an additional $201 million in funding set aside to further de-risk the project. The latter is focused on the mine’s scope of work, advancing other engineering and procurement activities, and preparation works for underground infrastructure, it said.

“This will enable an efficient transition of the project team between the study and execution phase, should the project be approved,” BHP said, adding that the release of funding to the project will be staged over this period.

The company, meanwhile, gave an update on its South Flank iron ore development, in the Pilbara of Western Australia, with CEO Andrew Mackenzie saying the project was 50% complete, with all major items on schedule and budget.

South Flank, which is expected to cost $4.6 billion to build, is set to replace production from the existing Yandi mine, which is reaching the end of its economic life. BHP is targeting first ore extraction at the operation in 2021 and expects to ramp up to 80 Mt/y of output.

Master Drilling continues down technology path amid global uncertainty

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Master Drilling Group included details of its remote drilling technology, commissioning of the Mobile Tunnel Borer (MTB) and the first phase of its shaft boring system development within its latest financial results release.

Reporting “reasonable results” for the six months ended June 30, 2019, which included a 3.8% year-on-year increase in revenue to $70 million and a 5.6% jump in headline earnings per share, the company’s CEO, Danie Pretorius, said Master Drilling had worked hard on stabilising new operations and growing its presence in new territories.

“In the face of continued uncertainty and volatility, which has inevitably impacted on business performance, we have remained committed to our strategic journey of diversifying our presence across geographies, commodities and sectors,” he said, adding that the company saw new business opportunities in Russia and Australia.

Even with only a slight increase in earnings and revenue, Master Drillings new business pipeline encompassing all geographies remained “solid” at $297.1 million, the company said. Its order book totalled $198.6 million at the end of the period.

Pretorius added: “While political and economic factors continue to shape our operating environment, at Master Drilling we continue to spearhead technological development, stabilise our global footprint and explore new business opportunities. As a result, the business remains stable and well positioned to benefit from an improved global economic climate.”

Master Drilling, one of the largest rock boring and drilling services providers in the world, spends the bulk of its capital spend on capacity expansion, some of which has begun to yield positive results, such as remote drilling technology, the company said.

“Having completed testing of this (remote drilling) technology in South Africa, Master Drilling has successfully implemented it in Mexico and Peru,” the company said. The test in South Africa took place 3 km underground at AngloGold Ashanti’s Mponeng gold mine, the world’s deepest gold mine. This saw a raisebore machine operated remotely.

Meanwhile, the commissioning of the MTB at Northam Platinum’s Eland mine, in South Africa, is currently underway, with underground drilling having already commenced, the company said. This follows testing at a quarry just outside of Rome, Italy, last year.

The first phase of the company’s shaft boring system – a new shaft sinking system (reported on in the annual shaft sinking feature in IM September 2019) – is also in the process of commissioning, the company said.

“This bears testament to Master Drilling’s unwavering commitment to technology development and testing, which will continue to be a key focus during the remainder of 2019,” the company concluded.

Shaft sinking complete at Caledonia Mining’s Blanket gold mine

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Shaft sinking at the new Central Shaft at Caledonia Mining’s 49%-owned Blanket gold mine, in Zimbabwe, has been completed, the company reports.

The Central Shaft project has been in progress since early 2015, with Caledonia spending some $44 million sinking a new shaft from surface to a depth of over 1,200 m.

Sinking of the shaft was predicated on increasing gold production to 80,000 oz/y of gold, compared with 54,512 oz produced in 2018 and the 53,000-56,000 oz expected in 2019.

The project now moves to the equipping phase prior to commissioning, which is expected during the September quarter of 2020, the company noted. Production from Blanket mine is then expected to progressively increase to the target 80,000 oz/y of gold from 2022 onwards.

“The company expects the increased production, combined with economies of scale and lower future capital investment, will result in significant increases in Caledonia’s profit and distributable cash,” it said.

Pre-sink of Shaft 2 at Ivanhoe’s Platreef underground project months away

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In a review of exploration and development activities in 2018, Ivanhoe Mines has gone into some detail on developments at Shaft 2 at the Platreef PGM-nickel-copper-gold project on the northern limb of South Africa’s Bushveld Complex.

This follows a project update issued just after the Mining Indaba event in February.

Shaft 1, expected to reach its final depth of 982 m below surface in early 2020, will ultimately become the primary ventilation shaft during the project’s initial 4 Mt/y production case, but Shaft 2, around 100 m northeast of Shaft 1, will provide primary access to the mining zones.

Ivanhoe said Shaft 2 will have an internal diameter of 10 m, will be lined with concrete and sunk to a planned, final depth of more than 1,104 m below surface.

It will be equipped with two 40-t rock-hoisting skips capable of hoisting a total of 6 Mt/y of ore – the single largest hoisting capacity at any mine in Africa. The headgear for the permanent hoisting facility was designed by South Africa-based Murray & Roberts Cementation.

Ivanhoe said nine blasts were successfully completed in 2018 enabling the excavation of Shaft 2’s box cut to a depth of approximately 29 m below surface and the construction of the concrete hitch (shaft collar foundation) for the 103-m-tall concrete headgear (preparations pictured here) that will house the shaft’s permanent hoisting facilities and support the shaft collar.

Excavation of the box cut and construction of the hitch foundation is expected to be completed in the June quarter, enabling the beginning of the pre-sink, that will extend 84 m below surface, it said.

In July 2017, Ivanhoe, which indirectly owns 64% of the Platreef project through its subsidiary, Ivanplats, issued an independent, definitive feasibility study (DFS) for Platreef covering the first phase of production at an initial mining rate of 4 Mt/y. The DFS estimated Platreef’s initial, average annual production rate would be 476,000 oz of platinum, palladium, rhodium and gold, plus 21 MIb (9,525 t) of nickel and 13 MIb (5,897 t) of copper.

Rock boring and remote drilling technologies highlighted in Master Drilling results

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Master Drilling might have faced a tough macroeconomic operating environment than previously expected in 2018, but the company was able to make progress on several fronts.

The company’s revenues increased 14.2% year-on-year to $138.7 million in 2018, while its headline earnings per share decreased 7.8% to $0.107.

Master Drilling CEO, Danie Pretorius, said notwithstanding the difficult trading conditions, the company “remained steadfast in the pursuit and implementation” of its strategy, “laying the foundation for future growth through the continued development of new, ground-breaking technologies, the expansion of our global footprint and by nurturing our client and business relationships”.

The company exited the year with an order book of $203.6 million and a pipeline of $578.6 million.

In terms of the company’s “ground-breaking technologies”, the company said it made progress on three fronts:

On the former, Master Drilling said, following testing at a quarry in Italy, the MTB was being shipped back to South Africa to take part in a pilot project.

It said testing of the Blind Shaft Boring system technology was also underway.

And, on the remote drilling applications, it had this to say:

“Recently, Master Drilling introduced Remote Drilling, which has been successfully commissioned at AngloGold Ashanti’s Mponeng mine, considered the world’s deepest mine.

“Remote drilling enables operation of an automated drill rig from a remote location. Master Drilling’s remote raise bore machine is currently working 3 km underground at Mponeng mine which is being operated from the contractor’s site office on surface.”

The Master Drilling remote system is a proprietary ‘plug and play’ control and display module that connects to the drill rig’s local control module through the mine’s underground and shaft communication network, it said.

“By removing all personnel from the dangerous underground environment, this self-driven mechanism has proven to improve production time and confirms that autonomous drilling technology is at the core of safer mining operations,” it said.

Murray & Roberts Cementation to sink ventilation shaft at Palabora copper mine

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Murray & Roberts Cementation says it has been awarded a contract by Palabora Mining Co for a 1,200 m deep ventilation shaft at its copper complex in Phalaborwa, Limpopo Province, South Africa.

The shaft, with a lined diameter of 8.5 m, will reach a final blind sink depth of 1,190 m before a drop raise takes it to its final depth, according to Braam Blom, Project Executive at Murray & Roberts Cementation.

“The duration of this project is expected to be just over three years,” Blom said. “After mobilisation, site establishment and surface civils have been completed, we expect to conduct pre-sinking until the end of 2019, with the use of our special shaft sinking gantry to a shaft depth of 65 m.”

A surface headgear and winder installation will then be constructed from January to March 2020. This will facilitate the slow sink to 200 m and the main sink until February 2022. Canadian shutter and lining methods will be employed, the company said. The team is expected to conduct shaft stripping by mid-April 2022 and to dis-establish the site by the end of May 2022, it said.

“There will be no stations or other excavations required, so this will help keep the team in a sinking cycle and optimise production levels,” Blom said. “We will run full calendar operations with 12 hour shifts and cycles of five day shifts, five night shifts and five shifts off.”

A relatively small labour force of 123 people is planned for steady main sinking conditions, with some sub-contractors conducting surface piling and civil works for the winder, headgear and other site construction. Shaft drilling itself will be done with two twin-boom Komatsu shaft drill rigs, and mucking by a Komatsu excavator with close to 1 t of loading capacity.

Blom said ground conditions were expected to be a challenge in some areas, as profiled from the cover and core drilling “However, we have various ways of reducing the risk and downtime during these intersections – such as keeping the shaft lining as close as possible to the shaft bottom,” he said.

Palabora operates a large block cave copper mine and smelter complex employing around 2,200 people, according to the company’s website. It has developed a $410 million underground mine with a production capacity of 30,000 t/d of ore.

Herrenknecht brings boxhole backreaming to shaft sinking market

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Herrenknecht expects to install one of its new boxhole backreaming machines in a mine in Asia later this year, one of the company’s Mining Project Managers, Alexander Frey, told attendees at an SME technical presentation, in Denver, Colorado, last week.

Looking to produce a system able to develop ore passes with simultaneous drilling and lining, the company has adapted boxhole boring machines it has been working on for the past nine years – which use an adapted form of the pipe jacking method – and come up with the boxhole backreaming machine.

This new machine can stabilise the shaft with thrust pipes and a steel liner, which avoids collapses of the shaft or a rework, while reducing the amount of activities in the upper level during mine development.

Herrenknecht has already built one machine and tested it at a mine in the Black Forest of Germany, Frey said. This testing saw the company sink an ore pass with a 2.8 m diameter and 22 m length at an angle of 19°. During this test work in 150 MPa Gneiss rock, Herrenknecht achieved reaming rates of up to 1.3 m/h, Frey said. According to Frey, the machine, which is equipped with a cutterhead like those employed on raiseborers, can cut really hard rock.

He added that the machines would likely be used for safely and efficiently sinking ore passes with a maximum 70 m shaft length and 3 m diameter, but it could also find other industry applications.

Variable rock mass pushes Rio off course at Oyu Tolgoi Underground project

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Rio Tinto has said completion of the Oyu Tolgoi underground copper-gold mine, in Mongolia, could be delayed for several months as detailed geotechnical data has revealed the rock mass is more variable than previously envisaged.

Oyu Tolgoi Underground is Rio’s major copper growth project. When the underground mine is fully ramped up, the existing open pit and underground, combined, are expected to produce more than 500,000 t/y of copper.

In Rio’s 2018 results, the company said the underground project continued to progress last year with the construction of critical above- and below-ground infrastructure. Detailed engineering design work and overall construction progress was mostly on track, with the main focus, in 2018, being on underground lateral development, the fit out of shaft 2 (the main production shaft), support infrastructure and the convey-to-surface decline.

Recent achievements at the operation, owned 66% by Turquoise Hill Resources (THR) and 34% by the Mongolian government, with Rio Tinto holding a majority stake in THR, include the completion of the overland conveyor connecting shaft 2 to the coarse ore stockpile, significant progress on the second underground crusher and the expansion of the central heating plant, Rio said.

“Overall, the underground lateral development has been proceeding well, with a total of 19 km achieved at the end of January 2019, against our second annual reforecast target of 19.8 km,” Rio said.

But, for the second quarterly report in a row, Rio flagged delays in completing the underground project.

“With the structural, mechanical and electrical fitout of shaft 2, it is now clear that the completion of this technically complex installation and commissioning work will be delayed by several months,” Rio said. “Delayed completion of the shaft, which provides additional hoist capacity to accelerate lateral development, will further delay the date we reach sustainable production beyond the nine-month delay indicated in October 2018.”

Back then, difficult ground conditions had slowed progress in some areas of the underground development, but, as the lateral development has continued, Rio said it had learnt more about the rock mass around and under the orebody and has access to more detailed geotechnical data than was available from surface drilling.

“This data reveals there are areas of the mine footprint where the strength of the rock mass is more variable than anticipated in the feasibility study,” Rio said. “This will require some potentially significant changes to the design of some future elements of the development and the development schedule.”

Detailed design work is now underway as is the work necessary to estimate the impact on cost and schedule from these changes and the delay in commissioning shaft 2, Rio said, while admitting that first production was unlikely to occur in the September quarter of 2021 as previously guided.

There were still many positive development takeaways from the mining major’s 2018 results, in addition to the record $13.5 billion it returned to shareholders as part of last year’s operational performance.

This included, among others, an update on the Kemano hydropower project in Kitimat, British Columbia, and the latest on AutoHaul™, the world’s first automated heavy-haul, long distance rail network.

On the former, a $500 million project in its aluminium business where Rio is constructing a required second tunnel at its hydropower facility, the company said it was expecting to complete the project by late-2020.

It will supply the Kemano powerhouse with water from the Nachako Reservoir, creating a back up to the original tunnel built over 60 years ago.

“We completed the starter tunnel in December 2018 and began boring the main tunnel in January 2019,” it said.

The company is carrying out this excavation with a 1,300-t tunnel boring machine (pictured) that will dig 7.6 km of tunnel through a mountain as part of a project to enhance the long-term security of a clean power supply for the BC Works aluminium smelter.

On AutoHaul, Rio said, in December 2018, it successfully deployed the autonomous rail network.

“Since completing the first autonomous haulage run in July 2018, we have steadily increased the number of driverless journeys, with more than 1.6 million km travelled autonomously in 2018,” Rio said.

The programme is now focused on optimising autonomous operations, according to Rio.