Tag Archives: SBR

Woodsmith-MTS-Anglo

Anglo American lays out 5 Mt/y Woodsmith polyhalite plan ahead of full design review

This week, Anglo American hosted an investor and analyst day at its in-development Woodsmith project, in the UK, with several key technology takeaways cropping up from an in-depth presentation from Tom McCulley, CEO, Crop Nutrients.

In reviewing progress and the past, McCulley stated that Anglo has decided to start Woodsmith as a 5 Mt/y operation, with a staged ramp-up planned to the 13 Mt/y rate. The plan to sink 1,600 m production and service shafts, establish a mechanised mine, construct the 37-km-long underground tunnel and build a materials handling facility with priority access export facilities remain part of this. The potential to phase ventilation & production level development within the underground mine, potential to phase conveyor upgrades in the underground tunnel and the potential to carry out a phased expansion as required for the export facilities are all options for the 13 Mt/y blueprint.

This change has required some of the scope to go back to study phase – hence the reason why Anglo has been mooting detailed design reviews and non-critical path studies – looking at how to optimise investment and modularise the construction to get maximum value from each phase, McCulley said.

“I feel far more comfortable today about how we are setting up the project for the long-term success but managing in a capital efficient way,” McCulley said during his presentation.

Some of the elements keen observers have been watching at Woodsmith are related to mechanised underground development – both vertical (via shaft sinking) and horizontally (via tunnel boring machines (TBMs) for the 37-km-long tunnel).

TBM-led tunnel transformation

In terms of the latter, Anglo American is soon expecting to set a World Record for the longest TBM tunnel developed by a single TBM. This is currently set at 25.8 km, with the Woodsmith team having already reached the 25-km (25.3 km) mark.

“Beyond this we will pass our next intermediate shaft at Ladycross, where we will take a 3-4 month maintenance pause as we set up the TBM for the final push to 37 km, and we expect to reach the Woodsmith mine in late 2026,” McCulley said.

The machine used at Woodsmith is a Herrenknecht hard-rock TBM that, McCulley says, works similarly to the Shaft Boring Roadheaders (SBRs) being used for shaft sinking (more on that soon) in that it cuts the soils, without blasting, and the material is transported through the machine and out of the tunnel via a conveyor that is part of the TBM.

“In addition to excavating the material, the TBM also simultaneously lines the tunnel via pre-cast concrete segments (six segments make up a ring around the circumference of the tunnel); these concrete segments are fabricated at the Teesside port by a project dedicated facility,” McCulley said.

He said in every measure the tunnelling on the project to date has been an amazing success, aided by a solid team performance. This team is made up of contractors from Strabag, Herrenknecht and Anglo’s in-house personnel.

Progress has been aided by consistent ground conditions across the tunnel within what is called Mudstone strata, McCulley said.

“These conditions are very predictable and cutting is easy for the machine which minimises the bearing wear, which is a key risk area for the TBM,” he said. “This consistent strata has allowed us to switch our strategy from three TBMs to one TBM for the entire 37 km, which means we will not only pass the World Record, but we will also smash it when we reach Woodsmith in late 2026. This reduction in TBMs had a knock-on impact of saving significant capital over what was originally planned.”

Anglo is consistently seeing average rates increase to over 20 m/d and trending closer to 25 m/d, which compares favourably with about 16-17 m/d in late 2021.

Tom McCulley-Anglo American
Tom McCulley, CEO, Crop Nutrients

SBRs on the up

Mine development via TBMs is relatively proven when compared with the use of Herrenknecht SBRs for shaft sinking in mining, with Woodsmith representing only the third deployment of the technology in mining following Jansen (BHP) and Nezhinsky (Slavkaliy).

Anglo has two SBRs on site at Woodsmith, sinking the production and service shafts at the project. Redpath, which carried out the shaft sinking work at Nezhinsky, is steering developments at these two shafts, in addition to the material transport system shaft. Only the much deeper production and service shafts are being sunk via mechanised means with the SBRs.

Overseeing this and all developments at the operation is Worley as an engineering, procurement and construction management contractor.

Sinking of the service shaft began in September-October 2022, followed some six months later with activities at the production shaft. McCulley said these two were now around 550-m deep and 340-m deep, respectively.

“We typically see more daily meters from the production shaft due to the service shaft lessons being applied to the production shaft, so I’m excited as I think we may have a race to polyhalite!” he said. “We are very pleased with the progress made on both shafts since Redpath started sinking in 2022.”

On the advantages associated with using SBRs, McCulley said: “Some of the primary benefits of these machines is they are inherently safer than traditional sinking. They also eliminate the need for explosives, which is a huge benefit to us with the community as we don’t encounter noise complaints experienced in other mines. I expect these machines to be the future of shaft sinking. They are just safer, quicker and more predictable.”

The SBR is generally working in autonomous mode for most of the time following a program with pre-set parameters for cutting, according to McCulley, who said the company is expecting an average rate of 1 m/d in each shaft over the full 1,600-m length of the shafts.

“This 1 m/d includes all routine maintenance and what we call non-routine work, like installing water cubbies for pumping water out of the shafts, probe drilling, tubbing and grouting,” he said.

“Ultimately, this is the right machine for the job at Woodsmith and the cutting rates we achieve are 1.5-2 times what we would do with traditional methods.”

Looking at current sinking progress and plans to hit the orebody in 2027 in the service shaft (with the production shaft being six months behind that), McCulley pointed out a 250-m section of sinking in Sherwood Sandstone, which the company expects to reach next year.

“This 250 m of strata will see our rates reduced from our 1 m/d to something between 0.5 m and 0.75 m a day, and this will impact us for most of next year and early 2025,” McCulley said. “Once through that strata, we do not expect any further issues with the ground conditions significantly impacting production.”

The Sherwood Sandstone is characterised as a strata of highly competent rock, about 120 Mpa, according to McCulley, which is at the top end of the SBR rock hardness capacity given by Herrenknecht.

In addition to the hardness, this strata has the potential for some water fissures (ie cracks in the rock with high pressure water), according to McCulley.

“The good news for us is we hit a 2.5-m layer of this material a few weeks ago and we learned from this that we need to make some adjustments to our cutter heads and cutting picks, and now we are far more prepared than we would have been otherwise,” he said. “We are also prepared with alternative plans, including potential use of lasers, plasma blasting and/or microwaves if needed, but we expect our updated cutter head and next generation picks, developed by Element 6 of De Beers, will cut through the rock at the rates I previously mentioned. In addition, to the hard rock, this strata has a risk of high-water flows in small sections of the strata so we will need to seal the shaft via grout from the shaft. This means as we come across water, we will inject chemical grout into the fractures to block water bearing cavities and control water inflow.”

Adding to McCulley’s confidence is the fact that the nearby Boulby mine encountered the same strata some time ago, which that team progressed through via the same exact grouting technique Woodsmith is planning today.

In terms of priorities for 2023, McCulley said the team expected the service shaft to be between 650-700 m at the end of the year, versus the current circa-550 metres today, whereas the production shaft could reach 450 m by this point.

“Both shafts, if they hit the numbers noted will exceed our planned targets for the year,” he said.

“The MTS shaft and Ladycross shafts are both sunk, and we are working to fit them out during the remainder of the year. In the tunnel we have driven 4.3 km this year, we are at 25.3 km and we expect to reach 27 km, which is our stretch target for the year.”

For 2024, while Anglo continues to work through the studies, it doesn’t see any changes to its plans right now and still expects to be around the $1 billon capex number for the next few years.

McCulley added: “Our vision at Woodsmith with regards to technology is to ultimately develop a peopleless underground mine, where operations and maintenance are all controlled from the surface. This is a journey, but many technologies are already out there, we just need to put the system in place and the wherewithal to help the vendors take the next step. This will not happen from the start, but with our vision and with the team we have in place, I have no doubt that in the future this vision will become a reality.”

When at full production, Woodsmith will be a FutureSmart Mine with all the modern technologies, according to McCulley, with these characteristics ensuring the company has a low cost, high volume mine for many years to come. Continuous miners are expected to be used in a room & pillar mining application, combined with mine cars, shuttle cars or conveyors.

“On top of the mining/processing technology, I see some interesting parallels with the farming industry. They are rapidly adopting technologies, and we are very well placed to support this transition in areas like sensing, scanning, AI, etc. I think with our Anglo American Woodsmith project experience in technology we are uniquely positioned to help support this transition in farming and this is something that will have added value to our product for years to come.”

Woodsmith Shaft Boring Roadheaders about to re-start cutting process

One of the most-watched shaft sinking projects in the sector right now is located in the UK, with the Woodsmith project in north Yorkshire having been on the radar for a number of reasons.

First off, it is a project that has changed hands recently.

Originally guided by Sirius Minerals, the 10 Mt/y project was acquired by Anglo American in 2020, a transaction that came with a fresh look at the whole project execution phase.

The change in ownership and re-assessment of plans drawn up by Sirius – a much smaller company guided by different investor pressures and operating procedures – led to Anglo American relieving DMC Mining, the lead shaft sinking contractor, of its duties.

Another reason for watching the project is the planned use of Shaft Boring Roadheader (SBR) technology from Herrenknecht.

After debuting at the Jansen potash project in Saskatchewan, Canada, where it excavated two 8-11 m diameter blind shafts down to circa-1,000-m-depth with the help of DMC as the contractor, SBR 2.0 – the second generation of the technology – was put to the test in Belarus at the Slavkaliy-owned Nezhinsky potash project. It ended up breaking shaft sinking records under the guidance of contractor Redpath Deilmann on a project to sink two 8-m diameter shafts (one to 750-m depth and one to 697-m depth).

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

The SBR is a 60-m tall, suspended shaft sinking machine, with 12 work decks and two service platforms. A telescopic, boom-mounted cutting head is used to precisely excavate rock via a partial-face cutting method. The cutting head works in a cycle, starting each cut from shaft centre to shaft wall, repeating until a layer of material is removed. Excavation proceeds in 1-m increments, followed by SBR lowering sequences.

The SBR was chosen for Woodsmith by Sirius over the conventional drill and blasting method due to its advantages in improving safety and schedule. This methodology, Sirius said, would allow the company to satisfy several operational objectives, moving away from the use of explosives and providing a safer, more predictable work method. Instead of a linear process, the SBR allows work to be completed concurrently as the shaft is sunk, as well as minimising damage to exposed host rock, and further improving safety while minimising downtime. Work decks above the cutting head allow workers to install shaft lining and tubbing as excavation continues, while a pneumatic mucking system removes waste rock.

The third generation of technology – which builds on the first two deployments with, among other things, the addition of two retractable robotic probes to test and grout the ground ahead for safer excavation and an additional control cabin on surface for more remote operation – is due to sink production and service shafts with 6.75-m diameters to depths of 1,594 m and 1,565 m, respectively, at Woodsmith based on the Sirius plan.

These SBRs are being supported by four triple sheaved winches from SMS SIEMAG and conveyors from Herrenknecht-owned H + E Logistik GmbH, among other support equipment.

Work on the service shaft commenced in 2021 with former Anglo American Chief Executive, Mark Cutifani, confirming in July of that year that the “first cut” with the SBR had taken place in the service shaft.

This progress was made while the company was still completing a detailed technical review on Woodsmith to ensure the technical and commercial integrity of the full scope of its design. This review has a particular focus on the sinking of the two main shafts, the development of the underground mining area, and the changes required to accommodate both increased production capacity and the more efficient and scalable mining method of using only continuous miners, Anglo American said.

Since the first cut was made in July 2021, however, Anglo American and Redpath Deilmann – which is now leading the sinking project as shaft sinking contractor – have been reviewing the existing plans for sinking with the SBRs, carrying out minor hardware changes on the machines and ensuring all staff have the appropriate training to facilitate the completion of the shaft sinking process. The Redpath Group is also involved in the drill-and-blast-based sinking for the materials transport system (MTS) shaft.

Various shaft sinking rates have been mooted in the past at Woodsmith, and Anglo American is currently working to develop the optimal solution for the facility based on technical standards.

The sinking at Woodsmith represents a different challenge to the two previous SBR projects conducted to this point.

For starters, there is no ground freezing expected to take place at Woodsmith – unlike what happened in Canada and Belarus. This process, while time consuming and only used to freeze unstable water-bearing strata around the shaft, can create more rock uniformity to aide consistent cutting rates.

There is also the MTS level to consider at Woodsmith, with plans to carry out lateral development work around the 360-m-level to join up the production shaft with this level where polyhalite ore will be transported along a 37-km tunnel to Wilton near the port. This means vertical cutting and loading may be halted while the MTS level connection is established.

All these factors, along with the performance of previous SBR work, will be incorporated into the engineering work Anglo American is carrying out at Woodsmith, but, in terms of the SBR, signs are that work on the service shaft could recommence shortly, with plans to start sinking in the production shaft by the end of the year.

Anglo American eyes polyhalite potential with Sirius Minerals bid

Anglo American has gone public with a bid to buy Sirius Minerals and its North Yorkshire polyhalite project in the UK.

The all-cash bid, which values Sirius at £386 million ($507 million), comes shortly after Sirius announced a strategic review for the project that included a broader process to seek a major strategic partner for the asset.

Anglo says it identified the project as being of potential interest some time ago, given the quality of the underlying asset in terms of scale, resource life, operating cost profile and the nature and quality of its product.

The North Yorkshire polyhalite project, which is spilit into two stages, will see product extracted via two mine shafts and transported to Teesside, in the northeast of England, on a conveyer belt system in an underground tunnel. It will then be granulated at a materials handling facility (MHF), with the majority being exported to overseas markets.

Infrastructure development on the project includes sinking the shafts at the Woodsmith mine to access the polyhalite deposit (using Herrenknecht’s Shaft Boring Roadheader); developing a 37 km-long underground mineral transport system using tunnel boring machines; constructing a MHF in Teesside for granulating or chipping the mined material into the final product; and harbour facilities comprising an approximately 3.5 km-long overland conveyor, a ship berth and a ship loader located adjacent to the harbour on the River Tees.

In its announcement this morning, Anglo said: “The project has the potential to fit well with Anglo American’s established strategy of focusing on world-class assets, particularly in the context of Anglo American’s portfolio trajectory towards later cycle products that support a fast-growing global population and a cleaner, greener, more sustainable world.”

Anglo is not new to the fertiliser market having, until 2016, a phosphates business in Brazil. It sold the mine, beneficiation plant, two chemical complexes and two further mineral deposits that made up this business that year to China Molybdenum in a $1.5 billion deal that also included its niobium assets.

Sirius announced its strategic review back in September 2019 after it had to terminate a $2.5 billion revolving credit facility stage 2 financing for the project (to get it to 20 Mt/y capacity) due to a worsening of market conditions for a required bond raising.

This led to the company slowing development across the project in order to preserve funding to allow more time to “develop alternatives and preserve the significant amount of inherent value in this world-class project”, Chris Fraser, Managing Director and CEO, said at the time.

This saw the company lay out a pathway that would still see first polyhalite production in the June quarter of 2022, but could see the ramp-up to stage one 10 Mt/y polyhalite capacity reached in the September quarters of 2025 or 2026, depending on if there was a 12 or 24 month deferral of the planned development scope.

Anglo said, during the first two years after an offer is successfully completed, development work on the project is expected to be broadly in line with Sirius’ revised development plan “although Anglo American intends to update the development timeline, optimise mine design and ensure appropriate integration with its own operating standards and practices”.

It added: “Anglo believes that the project has the potential to become a world-class, low-cost and long-life asset. Sirius has progressed the development of the project to an advanced stage, with construction now under way for over two years.

“Sirius has indicated that this is currently the world’s largest known high-grade polyhalite deposit with a JORC reserve of 290 Mt, with a grade of 88.8%, and a resource of 2,690 Mt. The resource indicated by Sirius has the scale, thickness and quality to be mined efficiently using bulk mining methods through a relatively simple, low-energy, non-chemical production process.”

In addition, Sirius has indicated the project could operate at an EBITDA margin potentially well in excess of 50%, according to Anglo, leaving the project well positioned for strong through-the-cycle profitability with a long anticipated asset life.

“At this stage, the project requires a significant amount of further financing to develop and commission the operation that has proven challenging for Sirius to procure on an economic basis,” the diversified miner said. “Anglo American, as one of the world’s leading mining companies, has the resources and capabilities to help build on the achievements of the Sirius team. Anglo American remains committed to its disciplined capital allocation framework.”

Anglo explained that there is potential long-term benefits in applying its technical expertise in both the development and operational phases, as well as utilising its recognised Operating Model to drive safety and productivity to “world-leading standards”.

“Integration into Anglo American’s global marketing network would provide full mine-to-market capabilities and build on Anglo American’s institutional experience in the world’s major fertiliser markets,” it added.

Sirius’ polyhalite product, POLY4, is a multi-nutrient fertiliser certified for organic use and has the potential to generate demand at a competitive cost that supports a strong margin, according to Anglo.

“POLY4 is an attractive low-chloride alternative to traditional potassium-bearing mineral products on a cost-effective basis. It includes four of the six key nutrients that plants need to grow – potassium, sulphur, magnesium and calcium,” it said. “The use of fertilisers is one of the most effective ways to improve agricultural yields and therefore help to address the anticipated future imbalance between food, feed and biofuel demand and supply caused by a fast-growing global population and limited additional land availability for agricultural use.”