pleted in 2010 mining is now sche- duled to continue until 2029. The latest technology including Atlas Copco Pit Viper and SmartROC drilling rigs is helping Boliden to double concentrator throughput of low-grade copper ore and deliver a competitive concentrate to its Swedish smelting and refining complex.
The Aitik 36 project has increased ore production, and has put Aitik on pace to reach 36 Mt/y by the end of 2012.The investment will make Aitik one of the most cost-efficient mines in the world.
state-of-the-art and larger scale con- centrator would be technically and economically able to continue recov- ering concentrate from significantly lower grade ore reserves at Aitik. The available tonnage would allow Aitik to process 36 Mt/y by 2014 and continue production until 2029. Concentrate shipment to Rönnskär could be improved by building a rail spur from the mine site to the main line instead of trucking the material to the station at Gällivare. The €600 million ($845 mn) Aitik 36 Project was launched in 2007; the new transport and processing sys- tems came fully on-stream in April 2010 and the official opening by King Carl XVI Gustaf was held on August 1, 2010.
The mining operation in Aitik is ba- sed on proven and probable reserves of 710 Mt. As of December 2011 proven reserves totaled 486 Mt, grading 0.25% copper, 0.15 g/t gold, and 1.6 g/t silver, while probable reserves were 224 Mt. Although the grade is low, Aitik does get a little help from nature due to the good rock conditions that enable’s the mine to have really steep slopes – 47°
on the footwalls and 52° on the hang- ing wall. This means they don’t have to mine too much waste rock. For the Life of Mine the waste-ore strip ratio is as low as 0.5:1.
To achieve the required ore extrac- tion rate the Aitik 36 project team decided to cut back the pit boundary in a number of places and to mine down to 600 meters. A supplementary open pit has been developed at Salmijärvi, one kilometer southeast of the main mine. Currently, Salmijärvi is at 60 meters depth with plans to reach 210 meters depth in approximately 10 years. Nils Johansson said, “Today we’re mining the southern part [of the mine] for ore and the northern part for waste, head- ing for ore. And then there are two levels active in Salmijärvi as well, so we have two main fronts and two sec- ondary fronts."
In all more than 80 Mt/y of rock will be moved and Aitik 36 included a largely new in-pit crushing and con- veying system to contain mine site rock haulage costs as well as additional new shovels and trucks. Boliden under- took a thorough evaluation of available
options in 2007 and decided to continue primarily with electric-powered equip- ment. Loading and haulage capacity would be raised by buying new models from the suppliers of the existing fleets. But the drilling rigs evaluation persuaded Boliden to switch suppliers.
drill fleet build-up
Aitik’s primary blasting requirement is to produce a fragmentation suited not only to the loading, hauling, crushing and conveying equipment but also to the grinding system Boliden favors. They’re doing so using auto-genous milling, which means it’s important to get the drilling and blasting right.
The blasthole drilling effort at Aitik has been shared between Boliden per- sonnel doing the bench production drill- ing and an NCC team contracted to do the pre-splitting. Aitik chose to retain this division of labor so NCC was able to continue using its Atlas Copco ROC L8 machines for downhole drilling straight contour holes. Boliden, on the other hand, needed to upgrade their fleet of large rotary drill rigs with four
Boliden undertook a thorough evaluation before deciding to invest in four new Pit Viper 351 rotary drill rigs. Boliden’s criteria included the ability to drill 311 mm holes to a depth of 19 meters.
Top: Nils Johansson, Drill Supervisor. Bottom: Peter Palo, Drill Superintendent and acting Mine Manager.
new units. The project team’s primary criterion was the ability to single pass drill 311 mm diameter holes to a depth of at least 19 m: drilling big 311 mm holes going 16 to 17 m deep eliminates the risk of deviation, points out Peter Palo, Boliden’s acting mine manager and development superintendent. Also extremely important for the fragmenta- tion is the positional accuracy of each hole; the more accurate the holes, the wider the pattern can be. That way Aitik can actually save drill meters and drill fewer holes. Ability to drill the right hole depths is also important, with smooth blasting to yield good flat surfaces for the large loaders and trucks.
Drilling to the right depth also means there will be less loose rock to drill through on the next level down.
Consequently, the team looked for features such as finger-tip joystick con- trols, programmable automatic drilling modes and GPS-based hole naviga- tion. Other major considerations were good built-in safety and productivity enhancing features such as an opera- tor-friendly cabin, ease of raising and
lowering the tower for tramming, and the ability to drill angled holes.
However, operators’ opinions regar- ding the merits of the various models available were therefore particularly important and Boliden was able to take some of them to the Atlas Copco Drilling Solutions (ADS) premises in Garland to check out the Pit Viper rigs. Palo says the feedback was clear; the operators preferred the ergonomics of these machines, especially the joystick control. Equally, the electric version of the hydraulic drive rotary head Pit Viper (PV-351) met the Boliden manag- ers’ requirements as to drilling capa- bility and ease of operation. Indeed, commented Peter Palo, the team was convinced that the Pit Vipers were the most advanced rigs of their kind on the market. “I can tell you that if we looked at the market today, there’s little com- petition, said Johansson. “It’s the most modern machine on the market, and it’s been proved in the availability as well.” According to Johansson, the Pit Viper 351’s availability is 95%. “It’s really, really extreme,” he said. As of July 2012, the four PV-351’s have logged
between 11,000 to 15,000 drilling hours since they arrived on site in 2009.
Striving for automation
Atlas Copco’s Rig Control System (RCS) technology has a number of benefits, and Boliden’s technical department took notice. Johansson said, “The probability of being able to use the autonomous functions in the future is a big reason that they wanted to buy Atlas Copco rigs.” Using automated features, such as drilling, tramming, and leveling is an attractive option for Aitik’s mine personnel, but it’s something they won’t fully implement until the future.Boliden and Atlas Copco agreed to operationally test the Pit Viper 351’s automation software back in 2009. The products were put under testing and development dating back to 2009 and the operational testing began in April 2012. The culminating test is to put a full drill plan in and to have the rig achieve predictable and repeatable results consistently.
Due to the overwhelming success of the new expansion, more focus on
The PV-351, installed with RCS, offer features like finger-tip joystick controls, a comfortable cabin, ability to drill angled holes, and ease of raising and lowering the tower for tramming.
the drills autonomous capabilities has been implemented by mine personnel. According to Johansson, all full-time drill operators have been trained on the autonomous functions, auto-drilling and auto-leveling, but auto-leveling seems to be favored by the drillers. “The drillers are using it more and a lot of drillers like to drill manually; the older ones,” said Palo. “The younger ones drill automatically.” But, how fast and how a fully-autonomous rig will be utilized remains in question among mine personnel. Depending on who you ask, the goal to become fully autonomous will be within the three and ten year range.
When asked about how automation will improve productivity at Aitik Palo responded, “I’d really like to see it,
because we can drill on a shift change and dinner breaks and so on, and we can speed up production by at least 10-15%.” Johansson has set-up five shifts during the week running eight hours each, with 12-hour shifts on the weekend. That makes for a 24-hour day in which the rigs are being utilized 65% of the time. “We have downtime when we change the shifts, but it’s not something that we worry about,” said Johansson. “We do pay the operators to have the opportunity to change shifts at the rig, but today we don’t have to because of the uptime on the machines, and also the planning ahead and everything is at a level where we don’t actually have to worry.” Drilling during 80% of the shift is the goal for Aitik, and using a fully-automated rig
is how they plan to get there. Aitik will be using its Pit Viper 351’s fully autono- mously at different points throughout the day in the future. Johansson states that one of the biggest benefits of run- ning a rig autonomously is less down time for shift changes and dinner breaks. Using the rigs autonomously during shift changes and dinner breaks could increase drill time to 80% each day. Many people relate fully-autono- mous functionality to staff reduction, but Johansson states that’s not the case. “They see [drill operators] autonomous drilling as a huge part as they’re partici- pating in a project where we’ll eliminate their jobs, but we don’t have any plans to eliminate their jobs,” said Johansson. “If anything we’ll add to our staff and it’s a way to increase safety.”
Not only does the RCS enable drill and blast plans to be loaded directly into the rigs’ computers, the system also provides a high level of automa- tion, such as GPS hole navigation – a major contributor to hole depth qual- ity – plus remote tramming and auto- drilling as well as auto-leveling. The Desktop Viewer allows remote mainte- nance problem-solving. Moving about the PV-351 is safe and four cameras provide good visibility where there is no sight line. The 65 ft tower can be lowered in eight minutes or less, enabling much quicker relocation times than some competing rigs can achieve. The angle drilling option is relatively expensive, but Aitik calculated that having it fitted to just two of the four rigs would achieve the degree of opera- tional flexibility required.
Preparations for delivery of the PV-351 machines started during 2008, including training at the fac- tory in Garland, TX for Swedish Atlas Copco rig assembly and maintenance personnel and for Boliden operators. Assembly of the first machine was completed in January 2009.
The local Atlas Copco team worked with Aitik engineering personnel under the guidance of Atlas Copco experts from Garland. The rigs are maintained by Aitik staff assisted by an Atlas Copco technician, with servicing after each 250 hours of operation.
In June 2012 Boliden reported 95% availability. Atlas Copco has also
One of the four Pit Viper 351 drill rigs at the Aitik Mine: The Atlas Copco Rig Control System (RCS) offers a wide range of features for automation, safety and communications.
continued to provide training for new operators, and plans to continue run- ning culminating tests to drill an entire drill plan in a predictable, repeatable form. Atlas Copco engineers continue to create interfaces for autonomous operation, but are working with mines to define a new role of what an operator actually is.