Not so. In fact, Salmi told E&MJ in August, the mine has achieved the target output rate, despite some slippage in equipment delivery schedules, and optimization is in focus. But Kemi has also already had to raise the ore production rate and to start a major expansion.

The reason for the immediate increase in ore output is that Kemi will renovate the heavy medium separation plant that yields 10- to 120-mm upgraded lumpy ore (grading 35% Cr2O3) and needs to stockpile this product ahead of the project. Output has been raised by approximately 10,000 mt/month so that production will increase to nearly 1.3 million mt in 2008 and will be 1.3 million mt in 2009.

The expansion is, of course, in response to Outokumpu’s €420-million F3 project, made public in June this year, to double ferrochrome production at Tornio to 530,000 mt/y (See E&MJ, July/August, p. 32). This project, to be completed at the end of January 2011, will make the company’s stainless steelmaking facilities comfortably self-sufficient in ferrochrome and possibly enable the company to take advantage of ferrochrome spot market opportunities to a greater extent than it can at present. And, Outokumpu calculates, the expansion will reduce global carbon dioxide emissions by 1 million mt relative to sourcing the ferrochrome from South Africa or Kazakhstan.

The project did not come as a great surprise to Kemi, said Salmi: the Kemi concentrator and Tornio ferrochrome plant capacities have been a bottleneck between readily available mining and steelmaking capacity and the company had been mulling a ferrochrome expansion since the 1990s. The investment covers a third ferrochrome furnace, a new concentrator line to increase the output of 45% Cr2O3 fine metallurgical concentrate, a totally updated lumpy ore concentrator line and some new mine development.

Resource Evaluation
To meet the expanded ferrochrome plant’s needs, ore production must be more than doubled to 2.65 million mt/y. In this light Outokumpu plans a capacity of 3 million mt/y. With proven reserves of 38 million mt and 85 million mt of probable reserves, Kemi is not short of chromite. The orebodies extend through three main areas, Surmaoja in the southwest, the central section and the Viiamaa area in the northeast. All three have been open pit mined while the main hoisting shaft is located between Surmaoja and the central section where the present underground operations take place. All three contain further resources, the question is how best to mine the multiple orebodies to yield the necessary grades.

One immediate issue is an increase in stresses within the mine, which has caused some movement and a number of collapses. This summer the Finnish exploration drilling contractor Suomen Malmi Oy (Smoy) planned and carried out a core drilling program at the 475 m level, using Kemi’s Atlas Copco Diamec U6 APC rig and operators to drill 4.5-in. holes intended to yield geomechanical information.

On the detailed exploration front, the Diamec is presently determining the ore boundaries for each stope in the current mining areas, using three to five holes, mainly horizontal but with some up and down holes. These are drilled 10 to 20 m to locate the contacts on either side of the orebody. Some drilling upwards into the new mining levels is also underway. The deepest core drilling done to date has reached the - 650-m level but GTK has done contract surveys on the property to depths of several kilometres with Russian seismic equipment. The results are due by year-end and will provide information about the main ore section and extensions on the south western and north eastern sections for planning a new core drilling program to 800 m or 1,000 m. Meanwhile Kemi plans to buy a new core drilling rig for the ore determination on the -350 and -375 m levels.

Expansion Under Way
Extra production will initially be achieved by bench cut-and-fill (BCF) mining of two more levels—at 350 m and 375 m and upwards. These are above the current BCF stoping sections, with the open pit bottom at 210 m. Developing the new levels will require driving 11.5 km of new tunnels. Contract work started in September this year and should be completed by the end of 2010. Thereafter the contractor is scheduled to develop 5 km/y for stoping while Kemi personnel will drive the main roadways for stopes. Meanwhile Kemi personnel are working on extensions in the 400 and 500 m levels and will in future do 4 km/y of tunnel development. The main workshop on the 500 m level will be extended, with new offices and storage facilities. The mine has already started to add new operational personnel to cope with the higher production targets. There are 45 miners at present and 15 more are to be hired with two year’s training provided for new miners. More blue and white collar workers will also be recruited, raising the total workforce of the mine department to 94 by the end of 2010.

All future mine planning is being done by a project group at Kemi and the mine is looking to beef up its management structure to coordinate work in the extended mine. As manager-mining, Salmi will be assisted by a coordinator, with a manager for each key function—mine planning, maintenance, contractor supervision (one per shift), occupational safety, and infrastructure management. The mine planner and maintenance manager will each have a designer, these being new posts as are the coordinator, contractor supervisor and infrastructure management roles. Actual infrastructure development underground is carried out by a contractor, Maansiirto Jänkälät Oy, with 20 people operating from the mine’s 115 m level workshop.

Kemi is currently using two Atlas Copco Cabletec bolters similar to the LC model shown here.

The heavy medium separation plant renovation will start in mid-2010, again using Wemco Drum type separators but with updated technology. The fine concentrate expansion project will also include the removal of the remaining Reichert cones in the existing plant, some of which were replaced by spirals in 2003. Salmi confirmed that the switch to road haulage of concentrates has been very successful, with no accidents or delays, but Outokumpu will discuss the contract covering the expanded output with Finnish Rail as well as with road hauliers.

Rock Reinforcement
To address the geomechanical problems noted above, the stope support system has been enhanced with extra cable bolting and mesh in conjunction with careful analysis of each stope.

Swellex bolts are inserted cut by cut using the mine’s two Atlas Copco Boltec rigs with screen handling arm. As the stope drives are now also wider than before, a third bolter may be needed. Two layers of shotcrete are sprayed, using one older Normet Spraymec 1050 and a new 9050 machine that has been working since April 2007.

Subsequently, Kemi’s Atlas Copco Cabletec LC rigs ply their trade, bolting the roof with two cables per hole. The new Atlas Copco Cabletec LC rig was delivered in spring this year and has been used together with the prototype Cabletec—which Kemi jointly developed with the manufacturer— rather than replacing it. A third cable bolter will probably be required for stope drive preparation on the 350 and 375 m levels.

Salmi commented that that a successful outcome from the LHD automation project that Atlas Copco is progressing at Kemi, together with the mine’s underground loading and haulage contractor, could be a big help in future, particularly in view of the geomechanical problems. The system being tested utilizes the mine’s W-LAN network for data communication. This network was also used earlier this year by Forcit Oy and Orica for remote-controlled blasting.

The Finnish explosives company Forcit Oy does all Kemi’s charging and blasting. Kemi is maintaining its policy of keeping its crucial equipment fleet up-to-date and will replace the two Normet machines with new 60 Series units in December. The mine will also hopefully take delivery of a new Atlas Copco Boomer E2 C drilling rig and a Simba M7 C in February 2009. These too will replace existing units. The fact that selling machinery in good condition is rather easy at the moment does help of course, Salmi said.