Planning is key to staying on track at Sudbury mine

Not every discovery made in 2001 will be hitting its stride in 2009, but Xstrata Nickel’s NICKEL RIM SOUTH PROJECT is shaping up to be one of this industry’s brightest lights. Best of all, the project is setting the ultimate standard for mine development– faster and safer than ever before.

Such an accomplishment doesn’t just happen. It’s achieved by thorough early planning, which in turn allows for fast, efficient execution.

Conventional thinking was set aside. Project Director Greg Ashe (since transferred to Xstrata’s Brunswick Mine) said,”This isn’t the traditional phased underground mining project. We sank two shafts at once and got them completed three years faster than if we had used the traditional approach of sinking an exploration shaft first.” The ventilation and production shafts were begun in 2005 and completed last year.

The decision was made to proceed with development of the Nickel Rim Mine with Inferred Mineral Resources rather than upgrade the resources to Indicated and Measured. The influencing factors were the high grade nature of the mineralization, which would mitigate other technical risks, and the depth and attitude of the mineralization, which would make upgrading the resource time consuming and costly. The reward clearly outweighed the technical risk.

Ten thousand metres of lateral development and 80,000 m of diamond drilling are to be done this year. A 2,500-m-long, 15% internal ramp is in the works. Despite a hectic schedule, Nickel Rim is on-time and on-budget while other projects are stalling due to uncontrollable labour and material costs.

Nickel Rim benefits from its location on the east rim of the Sudbury Basin. The geological knowledge gained from a century of exploration and mining the basin and the dedicated people who stayed with the project after Xstrata bought out Falconbridge made it possible to move quickly toward production. The proximity to Sudbury also meant there was a pool of skilled labour from which to draw. Not every new discovery enjoys these advantages.

Despite such advantages, no project such as Nickel Rim could be fast tracked without the talents of engineers and contractors with specialized abilities. Geologists are credited with having made a very reliable block model. Planners have devised a cost-effective method of bulk mining. Engineers have been flexibility into the design at every step. Experience has taught everyone an excellent understanding of grade control in the Sudbury Basin.

The desire to hire the best is evident in the list of contractors at Nickel Rim. Cementation Canada was awarded the contract for shaft sinking and lateral development. The engineering, procurement, construction and management work went to a 50:50 joint venture of Hatch and McIntosh Engineering (Hatch McIntosh Alliance or HMA). HMA has picked specialized subcontractors as needed to complete, engineering, mine planning and construction of the surface buildings and infrastructure.

Rick Collins, project manager, told CMJ that no one firm can do all the engineering work. “We looked for the specialists in each area, then our job is to co-ordinate the flow of information at all levels.”

The Nickel Rim project management philosophy is to maintain tight control over the schedule, break the project into manageable parts, and make decisions on a “best for project” basis. Individual contractors take ownership of their parts of the project. Everyone is clear on the goal, to create a safe, productive mine, and a strong and inclusive Nickel Rim South team has been created.

“Our EPCM approach has been a huge part of our success,” Collins said. “We are very proud of our cost control, which is linked to our schedule. And that all comes down to good early planning. Using the earned value analysis of costs, we are four per cent under budget.”

Safety first

The industry’s best safety record is part of what sets Nickel Rim South above other projects. In March 2008, the project recorded 3 million person-hours without a lost time accident. Approximately 4,300 people from 380 organizations and businesses have worked at the site in the last 4 1 /2 years.

Nickel Rim did it by adopting a “zero harm”program, asking questions about safety attitudes before hiring, and always putting safety at the front of people’s thinking.

As little as 25 years ago, shaft sinking crews used to expect that for every 1,000 feet of shaft that they sunk, there would be a fatality, explained Greg Ashe. That old idea is put to rest.

Ashe insists, “If what you are planning to do will hurt people, you shouldn’t be doing it.” Instead the project has adopted a top to bottom safety first message that is paying off.

“Whenever you put the focus on something,” said safety manager Dave Stephen, “it happens.”

The Nickel Rim safety culture is spreading to other mines in the Sudbury Basin because it works. Now that lost time accidents are a thing of the past at Nickel Rim, the next goal is to avoid medical injuries.

As Ashe said, “You can never, never stop trying to improve safety.”

Resources

The high-grade Nickel Rim South resource was discovered in 2001 between 1,400 and 1,750 m below the surface. The mineralization forms two distinct zones, the Footwall zone (FW), and the Contact zone. This is consistent with a Sudbury Basin Contact-Footwall Deposit Model containing The Nickel Rim property contains 14.5 million tonnes of inferred resources averaging 1.6% Ni, 3.1% Cu plus high PGM values.

A Sudbury Basin contact-type mineralized lens occurs in the immediate hanging wall above and sub-parallel to the Footwall zone. Sulphides in this environment are predominately pyrrhotite with lesser amounts of pentlandite and chalcopyrite. The distribution of sulphides tends from finely disseminated in the upper portions of the Sublayer through to semi-massive and massive sulphide along the lower contact of the Sublayer.

Footwall zone sulphides occur largely within strongly brecciated Sudbury Breccia that is located 50-200 meters in the footwall from the contact zone. Sulphide textures are substantially different from those within the Contact zone, with massive veins and stringers predominating. The Footwall zone is characterized by highly evolved copper-nickel-precious- metal-bearing sulphides that are strong- ly enriched with copper and precious metals relative to Contact type deposits.

Two distinct ore zones–the nickel-rich zone in the hanging wall and the copper-rich footwall–are apparent. Of the expected revenue stream, 55% will come from nickel, 26% from copper, and 19% from PGMs. That makes Nickel Rim less of a “nickel”mine and far more interesting.

Site development

An area of approximately 10 ha was cleared for the Nickel Rim South surface structures. The footprint is deliberately small since there is no mineral processing plant at the mine site. Ore from Nickel Rim will be trucked to Xstrata’s Strathcona mill.

The compact site is home for everything else a modern mine needs. There are ventilation (43-m-tall) and a production (60-m-tall) headframes with their respective hoist houses. The shop, fuel and lubrication facility, electrical sub-station, pump house and sewage treatment plant are arranged around the back perimeter. There is also a settling pond and a water retention pond.

Rounding out the buildings is the temporary office and dry complex. To replace it a permanent, modular administration building has been ordered from NRB of Grimsby, Ont. It will meet the Leadership in Energy and Environmental Design (LEED™) Gold standard. The builder is assembling the 100 modules in Hamilton, Ont.

The decision to contract out the administration building rather than build it on site is in keeping with Nickel Rim’s philosophy to focus on what its people do best, that is mine making not office construction. The decision als
o relieved congestion at a very busy development. The new structure is to be installed and in use in early 2009.

Another engineering decision makes the Nickel Rim South site unique. Then entire active site footprint of 10 ha has been paved. This was done to avoid any contamination if there should ever be a spill of something (motor oil), and clean up will be easy. This is the type of forward planning that creates an clean environmental record during development and operation of the mine .

Maintaining an operation without environmental contamination is paramount because Wahnapitei Lake, the drinking water source for nearby communities, is only 2 km from the mine property. The entire mine site has been paved to make clean up of potential spills effective. Paving also makes it easier to divert, collect and treat water runoff.

Nickel Rim South mine

CMJ’s tour of the Nickel Rim South mine with underground superintendent Jim Wilson began at the collar of the ventilation shaft. The shaft is 1,675 m deep and concrete-lined with a 6.1-m inside diameter. A used Nordberg hoist was installed for sinking, and it has been through this shaft that all development, drilling and mechanical teams entered the mine, six people at a time in a very small cage. Equipment and supplies went down this way too. Coming up of the vent shaft was all the mine exhaust.

When completed, the ventilation system will be a pull type with two 4,500-hp Howden fans pulling exhaust air out of the workings.

The production shaft is concrete-lined, 1.6 m diameter and 1,735 m deep. As well as the cage, it also accommodates a pair of 17.7-t skips and a 12-person maryanne. To keep all this moving, a 4.5-m-diameter Davy Markham double-drum hoist from England is installed. Two additional service compartments have been established. Fresh air is drawn down the production shaft.

When the production shaft is fully functional in April 2009, the temporary skip will be removed from the ventilation shaft.

The mine is developing on three levels– the 1280, 1480 and 1660. They are similar in layout, but CMJ toured level 1280. The drift is 5.3 x 5.3 m wide and is excavated in an elongated oval shape in the contact zone. Bisecting the middle, between the two long sides, is the opening for the garage. There is one garage on each level. A new electrical substation is also being established on level 1280.

Nickel Rim planners have devised a three-step program of ground support: scale and wash, shotcrete, and bolt.

They have chosen high-pressure water scalers (HPWS) that does exactly as the name suggests: remove loose material from walls and back with a jet of high-pressure water. This is not new technology, but the application is slightly different. There will be one per level.

Each level will also have a shotcrete system consisting of a rubber-tired mixing truck and Marcotte sprayer. An accelerant is added to the shotcrete to shorten curing times, and where extra strength is necessary, short polypropylene fibres are mixed into the cement. Openings are also bolted with 2.4-m rebar and resin

Each level will also have its own fuelling station, powder magazine, shotcrete system, and refuge station. Until the permanent refuse stations are built, temporary modular stations have been set in each shaft station.

The existence of two discrete ore zones– nickel-rich in the hanging wall and copper-rich in the footwall–led engineers to design a dual ore handling system to keep the two types separate. Rather than install an expensive underground crusher, two Teledyne rock breakers will reduce ore to -400 mm ahead of skipping.

Access to the mine was greatly improved by the long-awaited commissioning of the new 112 person cage on July 2. The new cage has the capacity to take an entire shift crew underground in one trip while they breath fresh air. The cage was fabricated by Stainless.

Technology.

With the larger cage in service, the job of handing over the mine to Xstrata crews begins. This will be accomplished in three steps. The first crew began training at the beginning of June and will be deployed in the mine as soon as the production cage goes into service. They will work on level 1280 to prepare it for mining the ore in April 2009. The second crew will begin training in December to take over level 1480 from development crews in January 2009. The third crew will take charge of level 1660 in July 2009 following a month of training. The production crews will be drawn from Xstrata’s existing workforce.

Going forward

By the time the Nickel Rim South mine reaches commercial production in September 2009, rigorous deposit definition will define the existing resource. There still remains a lot of unexplored ground around the new infrastructure that will continue to be explored from underground and surface for years to come to add additional resource to life of mine at Nickel Rim South.

In addition to the exploration potential on Xstrata nickel property, another significant undeveloped resource lies on Vale Inco ground. The nearby Victor deposit (2 km north of Nickel Rim) has been developed but is not active. It could be reached from the Nickel Rim underground workings and mined profitably.

Perhaps someday that will be the first step in a rationalized approach to mining and processing the ores of the Sudbury Basin.

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