February 2014

The next generation in nickel mining

The Sudbury basin has a long history of nickel production, and Totten, Vale’s latest operation, continues the tradition

By Correy Baldwin

The Sudbury basin has a long history of nickel production, and Vale’s latest mine – its first new nickel mine in the area in decades – continues this tradition. The Totten mine is also an ideal opportunity for the company to put a new set of tools to work in an old mining community.

“We anticipate that Totten mine will become a template for the development of other Vale mines in the future,” says Kelly Strong, vice-president of Ontario and U.K. operations. “It’s not often that we have the opportunity to build a new mine, so a decision was made early on in the project to build Totten with some of the best technology, automation and environmental management in the industry.”

Bob Booth, who oversaw development as senior project manager and who is now operations manager, agrees: “It began with the idea of how to build a mine with a potential for a 20-year mine life that would have a small environmental footprint with the highest focus on health and safety.”

Vale built its own management team to oversee project planning, and Booth says this in-house team – dubbed Team Totten – was key to successfully bringing the project through some difficult engineering challenges. “Numerous cost-­efficiencies were gained by utilizing internal resources,” he says. “And with a more thorough understanding of our organization, Vale’s own project team was also able to achieve more creative solutions to project challenges.”

Programmed logic

Totten is Vale’s most automated underground mine. One particular achievement is the automated ventilation on demand system (VOD). A series of vent-monitoring stations keeps track of ventilation volumes, as well as temperature, humidity, and carbon dioxide levels. All equipment and personnel cap lamps are equipped with radio-frequency identification (RFID) tags that are recognized by the system supplied by Simsmart Technology. Should the ventilation demands increase or decrease, control louvers and variable speed drives will adjust the volumes accordingly.

“Rather than supply levels that are inactive with expensive ventilation, we can direct the ventilation in the right places,” explains Erick Jarvi, chief engineer for operations. “If there are any issues that cannot be resolved with additional ventilation, the operations centre is alerted immediately and the operator is contacted. This system has drastically improved blast clearing times as well.”

Booth says the energy savings are significant: “We’re not wasting our community’s valuable energy on running a fan that isn’t required.”

VOD is just one part of Totten’s distributed control system, or DCS, furnished by ABB. The DCS – a first for Vale’s Sudbury operations – covers everything from ventilation and heating, to hydraulic pumps and motors, to the crusher, loading pockets, hoists and conveyor belts.

Mine automation commonly uses individual control boxes called programmable logic controllers (PLCs), each of which usually controls one component of the mining process. The DCS uses controllers similar to a PLC. These controllers are all tied together into one centrally controlled automation network that is monitored by the central control system.

“It’s basically a bunch of computers in the mine, all linked together, with the main brains located on the surface in a central computer bank, which communicates with the PLCs or controllers,” says Jack MacIsaac, automation lead at Totten.

“The central control room looks a bit like the bridge of the starship Enterprise,” jokes MacIsaac, describing the wall-to-wall computer screens with system-wide data and crisp video footage from throughout the mine. “Every system creates a visual graphic, which the operator can interface with.”

The DCS monitors and records data on the performance of every piece of equipment in every system, and is automated to adjust this performance when necessary, thereby maintaining efficiency.

“In the case of the VOD system, workers and machinery are tagged and tracked,” explains MacIsaac. “That information is gathered by the DCS system, which then makes adjustments to ventilation equipment automatically to ensure the air gets to where it is needed.”

An operator can access data in real time and interact with each system through the DCS to adjust various operations or correct systems if production variables change. Maintenance crews can track equipment performance to better diagnose a breakdown, or anticipate equipment breakdown before it occurs; and historical data can be analyzed to develop more effective maintenance schedules. Any deviation in a data set – raised engine temperature or RPM in a haul truck, for example – would set off an alert, to which the DCS and its operators would respond.

Data gathered by the DCS can be used to improve every aspect of running the mine. For Booth, it is a key component of personnel safety management: “We know where everyone is underground, as well as the equipment. We can monitor how they interact around the different workplaces to ensure that our people are working safely.”

“The DCS removes people from higher-risk jobs,” he says. “It reduces the risk of something adverse happening in that interrelationship of equipment and people.”

On the other hand, says Booth, this increase in automation increases the need for high-tech jobs. Vale employs two full-time operators working on the system, along with a crew of field workers and electricians. “We require fibre-optic specialists, networking specialists and wireless network specialists, and automation technicians who are familiar with DCS,” says Booth. “As well, production and maintenance employees are trained to understand the technology and automation features of Totten mine, and how those features impact their work environment.”

In total, Totten will employ a workforce of around 175 people. Some of these individuals come from Sagamok Anishnawbek First Nation due to employment and training opportunities made available in an Impact Benefit Agreement that was signed in 2012.

Vale worked with several contractors, including Cementation Canada, to bring Sagamok employees onto Totten’s construction teams, updating their skills through a new miner training program. Totten’s relationship with the Sagamok community continues into production, both through direct employment and through operational contractors. T. Bell Transport, which has been hired to haul ore from Totten to the mill, is hiring Sagamok members as drivers, mechanics and office staff.

Challenging ground conditions

The economic potential of the Totten mine ore body has been known for over a century. First discovered in 1884, Inco acquired the property in 1935, and sunk two shafts in the 1960s. But, says Jarvi, “the mine sat from 1972, flooded.” When Vale acquired Inco in 2006, the company immediately began plans to develop Totten mine. The second shaft sunk by Inco, which Vale planned to use for Totten, would have to be dewatered before any other work could begin. Vale contracted AMEC to design and build a wastewater treatment plant, which treated 300 million gallons of water pumped from the mine during the dewatering phase of the project.

“A lot of the original ground support had deteriorated,” says Jarvi. “When they were dewatering they discovered a lot of ground condition issues.” Totten brought Cementation Canada to rehabilitate the 40-year-old timbered shaft and bring it up to today’s standards. In 2007, Cementation assessed and stabilized the shaft, and also designed and managed the construction of a new head frame and hoist house.

“When you’re going into an existing mine access, like an old timber shaft, there are a lot of unknowns,” says Eric Kohtakangas, Cementation Canada vice-president of operations. “When you begin to pump the mine out, and you begin to expose things, that’s really when you begin to see the conditions. You’re also introducing air into the mine, and that’s when you start to get a little bit of rotting, until you can get the entire new infrastructure in place.”

“If you put water in any type of opening, it creates a certain amount of lateral force. It holds things in place.” Unstable ground conditions are created, explains Kohtakangas, when this pressure is taken away. And Totten was no exception.

These difficult ground conditions proved to be more extensive than expected, and necessitated a delayed start date (from March 2011 to the end of 2013) and a budget update (from $450 million to $760 million).

2013 was a busy year. By August, Totten had developed 43,200 feet of lateral mine workings. “We’re going to start out with two mining fronts,” says Jarvi, “one at the 3,150 level and another one at the 3,850 level. By 2016 or so, we’re going to establish a third mining front at the 4,170 level.”

An underground jaw crusher was installed at the 3,880 level. “We have a crusher that was installed in Elliot Lake in the 1970s,” says Booth. “We’ve had it refurbished with some of our engineering and fabrication partners to tie in hydraulic toggle technology.” The crusher will be capable of handling 2,200 tpd of fine ore, which will then be hoisted to the surface and shipped by haul truck directly to Vale’s Clarabelle Mill for processing, 40 kilometres away.

After a 23-month ramp-up, Totten will hit full production by 2016, running at 2,200 tpd, or 750,000 tpa.

A new geological model

Totten is situated along an offset of the Sudbury Basin, known as the Worthington Offset. This meant that although Totten is Vale’s sixth operating mine in the Sudbury area, the company could not model the mine after its other projects in the Basin.

“Our offset environment has presented some challenges due to contrasting rock properties,” explains Jarvi. “But as our underground diamond drilling programs got underway and development advanced, core logging and underground mapping began to develop a more complex geological picture of the Totten deposit.” Once the team was able to back up this data with visual confirmation of the different rock types and their interactions, strengths and structures, Jarvi says they were able to develop a dynamic ground control strategy.

The ore body itself is a high-grade nickel-copper deposit, also containing precious metals. “The ore body is very steeply dipping,” says Jarvi. “And the footwall and hanging wall contacts seem to be quite well defined, which is a benefit. It lends itself well to the blast hole stoping mining method we’ve adopted. It’s going to be a nice ore body.”

Totten currently has a 12-year mine life, with an additional eight to 10 years based on currently known mineral resources and exploration targets. Meanwhile, exploration drilling continues on the Totten property, and Booth is optimistic that Totten’s resource will grow: “If there’s one thing I’ve learned, it’s that we always mine below shaft bottom at any mine in the Sudbury Basin.”

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