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21st century arrives early at Kiruna.

New Ore Processing Facilities Completed, New Main Level on Schedule for 1997 Start

The first major phase of LKAB's investment project at its Kiruna operation is coming on stream. The new ore concentrator and pellet-plant installation has been completed and testing and commissioning is underway. The concentrator is expected to go into operation shortly and the pellet plant at the beginning of 1995. Work continues on the huge program to develop a new production level, and related facilities, in the underground mine. This phase of the investment program will not be fully completed until the turn of the century.

Confidence in the future is a scarce commodity in difficult times. LKAB is a brilliant exception. Just over a decade ago LKAB emerged from its "seven lean years". From the mid-70s until the end of 1982 the company lost an average of about SEK 500M/yr (some $70M/yr at today's exchange rates). Iron-ore markets collapsed, fixed costs were high, and LKAB was squeezed in the middle. In 1974 LKAB produced a record 30M mt ore. One year later shipments had collapsed to 21M mt and the red ink was starting to flow. By 1982 shipments were down to 13M mt and accumulated losses exceeded SEK 3B.

By the time LKAB got back into the black in 1983, production had been cut to 8M mt and the number of employees cut to around 3,300 from more than 8,000 in 1976.

But LKAB survived, and by the time of its centenary in 1990, its then president Wiking Sjostrand could already report that investments would be made at Kiruna for "...a new, large-scale mining system, a new haulage system including a new main level, and a new ore processing structure... the time also appears to be ripe to expand pelletizing capacity at Kiruna."

Furthermore, once the lean years were over and LKAB returned to the black, a combination of rationalization, cost cutting, good ore prices, and high demand resulted in some of the best financial results in the company's history in terms of kronor. Through improved planning and control LKAB reduced its inventories to a minimum and transformed tied-up capital into liquid assets. In the words of the then president Sjostrand, "We have succeeded so well that our cash coffers are brimming."

$550M Investment Program

Since then decisions have been take, and work wholly or partially completed on investments totally $500M at Kiruna alone. Cash-rich LKAB has been able to finance this huge investment out of its own resources.

These investments include:

* A new main haulage level in the mine at a depth of 1,045 m to extend the life of the mine a further 20 yr.

* A new concentrator for pellet-feed production.

* A new pelletizing plant raising LKAB's total pelletizing capacity by 4M mt/yr to 15M mt/yr. As a result of these investments, LKAB's total capacity for iron-ore products (including the Malmberget mine and plants and the Svappavaara pellet plant) will increase by 3M mt/yr to a level of 24M mt/yr.

The decision to make these investments was based above all on an analysis of the market. Since the 1960s LKAB's product mix has shifted dramatically. At that time, high phosphorus ores dominated and pellet deliveries were insignificant. In line with structural changes in the European steel industry, steel-making based on high-phosphorus ores has shrunk and will eventually be phased out altogether. Low-phosphorus sinter fines have remained a fairly constant proportion of the product mix, but a clear trend can be seen in the blast-furnace steel-making sector to move away from sintering strands for feed preparation--not least because of environmental considerations.

These trends mean pellets are where it's at, and that is where LKAB intends to be--indeed already is to a very large extent. The new pellet plant will raise the share of pellets in LKAB's production to 60% of volume and 75% of value.

Carl Ameln, LKAB president, says "We foresee strong growth in the direct reduction market in the coming years, while an increase in the use of blast-furnace pellets will be the result of more stringent environmental controls forcing many steelworks to abandon sintering in favor of pellets."

Total world pellet production amounts to approximately 200M mt/yr of which about one third is destined for the export market (the rest is produced/consumed internally by integrated steelmakers). Just over 80% of these export pellets are for blast furnace feed, the remainder are for direct reduction plants.

LKAB has achieved up to a 20% share of the world market for export pellets. In 1993 this market share fell back to around 15%. This was because new direct-reduction plant capacity/demand rose so rapidly that LKAB was unable to keep up with it while still servicing its existing customers.

In 1993 LKAB sold all the products it was able to produce, and in addition reduced its stocks to 0.9M mt. Shipments were 20.1M mt and production was 18.7M mt. The inventory thus reached its lowest level in recent history, indeed the company felt it was slightly too low for comfort.

LKAB has continued in 1994 with demand for its products still exceeding delivery capacity. Many contract customers in Europe and in the Middle East are demanding more pellets than they have contracted for.

The new concentrator and pellet plant will permit LKAB to immediately satisfy the demands of this growing market on top of its existing commitments. The timing has turned out to be excellent. The new capacity is coming on stream just when the demand is growing strongly, and LKAB will have no problem in disposing of its expanded pellet production. In addition, the recent investments have been made during a period of economic downturn in Sweden--when there were few other big projects for engineering and construction firms to bid for. Competition has been strong, and this has resulted in major savings in the cost of the investment.

Underground and Surface Projects

Half of LKAB's future oriented investments in Kiruna are being made underground and half on surface--in processing facilities. This article uses the nomenclature adopted by the mine, so a short course in Swedish acronyms is in order.

FPS, Framtida Produktionssystem, or Future Production System is the name given to the overall project which will assure mining at Kiruna well into the next century, and increase both production and product quality. It comprises two parts:

KUJ 2000, Kiruna Underjord, or Kiruna Underground, which refers to the investments in the underground mine. The largest investment here is in the transportation system comprising the new haulage, crushing, and hoisting facilities. The investments in mine operations themselves will involve the implementation of large-scale stoping systems, automation, and a new ventilation system.

SAK 2000, Sovring, Anrikning, och Kulsintring, or Dressing, Concentration, and Pelletizing is the part of the investment program covering the new concentrator and pellet plant.

The significance of '2000' in the project acronyms is self evident.

The largest single item in the FPS investment program is the new underground transport level, accounting for over SEK 1.7B at 1991 values. The main investment components (in billion SEK at 1991 values are as follows:
New transport level                   1.703
New ventilation system                  0.3
Increased production capacity           0.2
New concentrator                        0.4
New pelletizing plant                  1.05

Total                                 3.653


In current money, the investment total is over SEK 4B or almost $500M.

The payment schedule for these investments is shown in Figure 1 and the cumulative investment through the year 2000 in Figure 2. The general time schedule for the implementation and completion of the components of the FPS project is shown in Figure 3.

Cutting Freight Costs Too

The investment program will reduce internal costs at Kiruna, but there is an important external cost factor which affects LKAB. Products shipped by the railroad to Lulea in Sweden and Narvik in Norway have, in the past, incurred high freight charges levied by the Swedish and Norwegian state railways. In 1991 the ton-kilometer rates charged by these railroad systems were from two to four times as high as the highest freight rates paid by iron-ore shippers in Australia, Brazil, or Canada.

In January 1993 LKAB was able to take over the traffic rights for the section between Lulea and Riksgransen on the Swedish/Norwegian border. LKAB could, in theory, operate the railroad itself, but it has chosen, for the intermediate term at least, to use the state railroads as contractors. The three companies are now working together to make the transportation facilities as efficient as possible.

In 1993 LKAB's total manufacturing costs declined by SEK 500M or just over 15%. An important explanation for this dramatic decrease was the new ore-freight agreement that entered into force at the beginning of the year. LKAB says that a great deal remains to be done in the rail-freight area in order to bring costs down to internationally competitive levels. The goal is to achieve these levels by the time that the current freight agreement expires at the end of 1997. The development of new locomotives and new, larger ore cars will increase the payload per train.

In another transport-related project, LKAB broke the first ground last June for a new ore harbor in Lulea. SEK 290M is being invested in the new harbor which will be more efficient and flexible than the existing facilities. New and more efficient technology will be used in the entire chain from rail car unloading to ship loading. It is estimated that unloading a current train of 52 cars (4,000 mt ore) will take about 30 min.

High Quality Products

LKAB is one of the world's eight largest iron-ore producers. It has underground mines, concentrators, and pelletizing plants at Kiruna and Malmberget, and pelletizing plant at Svappavaara. Current ore production rates at Kiruna and Malmberget are around 20M mt/yr and 10M mt/yr respectively. All these facilities are north of the Arctic Circle in Swedish lapland. The ore products are shipped from the ports of Narvik in Norway and Lulea in Sweden--the latter is the seat of the LKAB head office.

An ore train from Kiruna to Narvik has 52 cars and loads more than 4,000 mt. Normally 13 such trains run each day.

LKAB is the only large-scale iron-ore exporter left in Europe. Some 85% of LKAB's products are delivered to steel mills in Europe. The balance goes to customers in the Middle and Far East. Although LKAB mines ore underground, while its leading competitors in Australia and Brazil have lower-cost open-pit mines, the Swedish company has one big advantage--nearness to the market. Its biggest customers are located only a few days by boat from its ore harbors. Its biggest single customer is the Swedish steelmaker SSAB. SSAB takes nearly 20% of LKAB's production, mainly for its blast-furnace steel plant at Lulea.

Higher transport cost for deliveries to its Asian customers are offset by the quality advantages these steelmakers gain from LKAB's high-quality pellets.

LKAB is the only pellet producer with complete flexibility between blast-furnace and direct-reduction pellets--or indeed any other conceivable grade. Because the ore is magnetite, which undergoes an exothermic reaction during sintering, the operating costs are low. As much as 68% of the energy needed for pelletizing is generated through the oxidation of magnetite and external fuel only accounts for 38%. A side benefit of this is cleaner operation, since air pollution is directly related to fuel consumption.

LKAB's first pellet plant, a shaft furnace, was put into operation at Malmberget in 1954/1955. From then on the company steadily invested in new capacity and new techniques. Further plants were put into operation at Kiruna in 1965 (a straight grate), at Svappavaara in 1967 (a grate kiln), and at Malmberget (steel-belt process) in 1973. The old Kiruna plant was replaced in 1981 by a new Allis Chalmers grate kiln plant. The oldest of the Kiruna plants has now been pulled down to make room for the new KK3 pellet plant.

Research has been underway for several years into a new type of pellets using an organic binder. Successful tests were conducted during 1993. The goal is to launch a new generation of pellets commercially in 1995. The new pellets are said to offer considerable advantages to steelmakers in the form of a more even and energy-efficient blast-furnace process, and a higher and more uniform quality steel.

LKAB's ambition is that its new generation of pellets should represent just as an important advance in technological and commercial terms as the launching of its olivine pellets in the early 1980s.

KUJ 2000--The Underground Dimension

The Kiruna magnetite deposit is over 4 km long, has an average thickness of 80 m, and a known depth of 2 km with a constant dip of 55 [degrees]. Since mining started just over a century ago, some 800M mt ore have been extracted. The remaining geological reserve is possibly over 1B mt. The remaining ore reserve, however, within the present mining limits above the main 775-m level is only about 110M mt. At current production rates this is barely sufficient to last until the end of the century. By developing the new 1045-m main haulage level, an additional 300M mt is added to the ore reserves.

LKAB is the only large iron-ore producer that mines underground. Kiruna is the largest underground mine, of any kind, in the world. The total paved road distance underground is some 400 km. To profitably mine iron ore underground, you have to be highly efficient. For decades LKAB has been a watchword in the industry for innovation and high-technology mining. Remote controlled loaders, drill jumbos, and trains are already in use, some for many years. Kiruna is probably the most visited mine in the world. Since the lean years of mid-70s and early 80s, when high fixed costs and a collapse in markets nearly drowned LKAB in a bath of red ink, Kiruna has come roaring back with a mine development program that will assure its future.

It is not only a question of building a new main level to insure that there is enough ore for mining operations to continue until about 2015. The whole mining system is being redeveloped to permit higher production/productivity and lower-cost mining--with much greater concentration and flexibility. Additionally, and very importantly, operations will switch to three-shift continuous, from two shift/d at present. The project plan for the new mining system was devised with the goal of reducing production costs by 25%.

Improved Transport System

Already in the mid-80s Kiruna engineers were considering the possibilities for a less costly and more efficient operations in the future. Starting in 1989 and 1990 planning groups were formed to design the new transport and mining systems that would be needed within KUJ 2000. The goal for the new transport system was that it must cost less to operate and maintain than the existing rail system on the 775-m main level. The goal for the new mining system was that it must reduce costs by applying large-scale, even more-automated operations--to allow concentrated, continuous mining.

The transport group investigated all options from big trucks (as used at Malmberget) to underground grinding and hydraulic hoisting. In the end it was clear that a railbound system, similar in principle to that used on the 775-m level, and vertical hoisting in skips was still the best solution.

The requirement for the system is that it should have a capacity to handle 26M mt/yr ore and continuously deliver it to the surface plants which operate on a 24-hr basis. The new level has the capability to deliver two ore qualities (and a third too if necessary). The Kiruna magnetite ore has varying quantities of impurities, of which phosphorus is the most important. Production from different areas must be segregated, or blended, in the transport system to meet the requirements of the surface treatment plants, and eventually of the customers.

Figure 4 shows how the the Kiruna mine has progressively deepened since it was first worked as an open pit just over a century ago.

The KUJ 2000 transport system basically comprises a new horizontal haulage level and a subvertical shaft system to connect it to the existing surface shafts. The 1045-m transport level accommodates a shuttle train system in which trains haul ore from eight groups of ore passes along the 4-km strike to the dumping stations at the new subvertical shafts. Each ore-pass group consists of three or four shafts. At full production, five 500-mt trains (driverless and automated) will be required on the new level. These trains, already operating on the 775-m level, will be transferred to the new haulage level as operations on the upper level decrease.

Through careful planning and computer simulation tests it has been possible to minimize the need for double-track transport on 1045-m level. From the ore passes right through to the entrance to the dumping stations, there will only be single-track operation. Double tracks are only needed where the trains unload at the crusher bins. This means much less development work, and also higher production reliability when in operation.

There are four dumping stations on the 1045-m level. The crushing stations below these will be equipped with the primary gyratory crushers moved down from the existing crushing stations on the 775-m level. The 1045-m level is planned to go into operation in May 1997, and the changeover from 775-m level operations will be completed in year 2000.

The four subvertical shafts will be equipped with rock hoists to raise the ore to the transfer station for the surface shafts. The present 775-m level shaft bins etc. will be used for the transfer station. At present Kiruna has eight surface hoists. Because of the change from two- to three-shift operations underground, it will be possible to assure surface hoisting with six winders. Two of the existing surface hoists will be refurbished and moved underground to join two new ones in the subvertical shafts hoist room on 740-m level.

The ore transport and dumping/crushing is automated and computer controlled. As in the existing haulage level, operators in a central control room supervise the loading of the trains from the ore-pass boxes via television monitors and remote controls. Normally, no workers are on the haulage level itself.

Below the new haulage level there is a sump for all mine water and a central pump station on 1065-m level. The total pumping capacity is 48 [m.sup.3]/min. There is an additional pump station at the foot of the subvertical shaft ramp system at the 1180-m level, the lowest point of the mine.

Large-Scale Mining

The mining method which will be applied below the 775-m level will be large-scale sublevel caving with vertical sublevel intervals of as much as 30 m. At present Kiruna's production is approximately 80% from sublevel caving and 20% from sublevel stoping. The mine will eventually move to 100% sublevel caving.

Since the late 80s the sublevel interval has progressively been scaled up from 12 m to 22 m to 24 m. Currently 27-m level interval layouts are being used. Below the 775-m level the first stopes will be developed with 28.5-m level intervals, and 30-m is the next goal (there are already some 32-m level interval stopes at Malmberget).

The 7-m x 5-m drill drifts are at intervals of 25 m along strike. Burden between fans is 3.5 m, and it may be possible to increase this to 3.7 m.

This increase in scale has important benefits for productivity and concentration of mining. Under the old system of 12-m level intervals, and 2-m burdens, one fan blast yielded about 1,500 mt broken ore. A 30-m level interval with 3.5-m burden between fans will yield about 14K mt broken ore per blast. Thus to achieve an ore production of 60K mt/d (corresponding to about 20M mt/yr), about 40 stope blasts would be required under the small-scale system, but only a handful will be needed with large stopes.

With the old layout, and scattered mining, blasting took place throughout the mine every evening. Because of this, and the mine layout and ventilation system, only two-shift mining was possible.

Referring to Figure 7 it can be seen how the new production level has been divided into eight production blocks along about 3.2-km strike length within the current mining limits. The block lengths vary from 336 m to 523 m and they contain from 34M to 41M mt ore each.

There are four main ramp systems along strike--each ramp serving two adjacent blocks. Each block is effectively an independent mining unit. The blocks have separate ventilation systems and they are linked to the four ramp systems in such a manner that continuous mining operations are possible. While one or more blocks are being blasted, others can be kept in operation. Because of the large fan tonnages, and the independent blocks, instead of mine-wide blasts, only a few fans need be blasted in, say, two blocks, while the rest of the mine continues to operate without interruption.

The ramps are laid out in a systematic manner so that the connections to each drilling level on the mining blocks come directly underneath one another. This gives great advantages with respect to servicing the mining levels and designing stoping strategies.

Figure 8 shows how the production blocks are connected to the footwall haulage system via eight groups of ore passes. Each group consists of three or four passes, making a total of about 30--compared to the 44 ore and waste passes required on the 775-m level. Each ore pass is about 280 m long and the total ore-pass development for the 775-1045-m block will amount to 8.5 km. There will be no separate passes for waste rock in the new mining level. The development waste will be mixed with high-phosphorus ore which will increase the dilution factor of this raw ore from 18% to 20%.

The 775-1045-m ore block will be mined in nine horizontal slices with the first slice mined from the 791-m level and the last from the 1020-m level. The development of the 791 sublevel is expected to start at the end of 1995, and cave drilling will start in 1996. First production will be in conjunction with the beginning of haulage operations on the new 1045-m main level in May 1997.

New Ventilation System

The ventilation system for the 775-1045-m mining block is a big, big project. Analyses of the future mine show an air requirement of 900-1,200 [m.sup.3]/sec. The new ventilation system requires 16 shafts from surface to provide each of the eight production blocks with its own intake and exhaust system. However, compared to the present system which has two distribution levels and about 50, upcast and downcast air-shafts, it is a simple system. The advantage of this is that it lends itself to automation and control. In particular, in conjunction with the new block-unit layout of the mine, it means that big savings can be effected in directing air only to where it is needed--and cutting off ventilation to areas which do not require fresh air at any particular time.

The 16 vent shafts will be 3-m-dia and total 16.4 km in length. They will be drilled by raise borer, each in two stages. The drilling will continue until nearly the turn of the century. The two vent shafts from each of two blocks are brought together in groups of four in four surface fan houses. The 16 new ventilation fans will be powered by Siemens speed-regulated AC motors. The electric motors are of the new 1LA8 design and total installed power will be 11.36MW. Siemens will also supply 16 digital frequency convertors. Kiruna is using a mine ventilation control system based on the PowerVent technology of Boliden Process Control AB. This system utilizes distributed PLC's with powerline communication and no separate signal cables to control fans, doors, etc. to achieve high energy savings.

Main-Level and Shaft Contractors

Figure 9 shows the time schedule for construction of the KUJ 2000 project. Rock excavation work on the new main level started in the fall of 1990. About 1M [m.sup.3] rock must be excavated to make room for the new facilities. To date about three quarters of the rock excavation is complete.

All of the new level and shaft development is being done by contractors. The main contractor for the new mining level is the KUJ-Bygg consortium formed by the two Swedish contractors Siab and Skanska. KUJ-Bygg was established in 1990 to undertake underground development and construction work in Kiruna. It employs about 75 people, with yearly billings of around SEK 75M.

By mid-1994 KUJ-Bygg had completed 15 km of drifts and rock caverns with cross sections from 16 to 150 [m.sup.2], which amounts to about 500M [m.sup.3] rock. Most of this work has been development and underground construction for the 1045-m level.

The first stage to be completed is a ramp down to the 1180-m sump level, the railroad switching/unloading station on the 1045-m haulage level, a rock cavern for the four crushers, a skip-loading level, four train-unloading and crusher bins, and several different service levels for the four new subvertical shafts.

The excavations are scaled by a sub-contractor using a modified Akerman 117 excavator equipped with a scaling head. All drifts are reinforced with 3 cm shotcrete and grouted bolts. In areas with very bad ground or in rock caverns designed to contain heavy machinery, 10 cm reinforced shotcrete and grouted bolts on a 1.5-m spacing pattern are used.

The next main excavation stage, which was recently started, is 12 km of main drifts amounting to 300K [m.sup.3] of rock excavation.

In August the first concrete construction stage started. Some 10K [m.sup.3] concrete and 2,500 mt steel will be installed in this stage.

Another major excavation project that is nearing completion is the underground bin for pellet storage. This bin has capacity of 10K [m.sup.3] pellets, corresponding to four trainloads. The great spans (50 m high and 12 m wide) and the fact that the bin is near surface means extensive rock support was required. The roof and walls are supported by 10 cm of reinforced shotcrete and 4-m grouted bolts on a 1.2-m pattern. The bin will be operational in January 1995.

For drilling, KUJ-Bygg has a fleet of one AMV and four Atlas Copco development jumbos, one Atlas Copco Simba 262C long-hole jumbo, one Atlas Copco 642 crawler jumbo, and one Tamrock Solo 3000 jumbo. Normally ANFO is used for charging, but in wet areas Dynamex (or similar) is used.

For raise work (ventilation shafts etc.) KUJ-Bygg uses Alimak raise climbers. The length of the Alimak shafts varies from 40-100 m and the cross sections are 12 [m.sup.2].

The main shaft and raise contractor for KUJ 2000 is the Swedish contractor Kraftbyggarna. Kraftbyggarna is drilling the four subvertical shafts using a Robbins 82R raise drill. The shafts are reamed out to 2.1-m-dia with the raise borer, and then slashed to final 24 [m.sup.2] cross section by drilling from a sinking stage.

Kraftbyggarna has also been entrusted with the program of surface ventilation shaft and ore pass development for the 775-1045-m mining level. The contractor will use three Indau raise borers equipped with Robbins 2.4-m-dia reamers, extendible to 3-m-dia. The drills will start working in November 1994 on the 16.4 km of vent shafts. They will also be used to bore the 8.1 km of 2.4-m-dia ore passes. This vent-shaft and ore-pass boring-phase is expected to take about five years to complete.

Precision Blasthole Drilling

The new large-scale stoping system will require drilling very straight blastholes up to 55 m in length. This calls for a completely new drilling system. The answer is the Wassara water-powered in-the-hole hammer. This drill has been developed by the LKAB subsidiary, G-Drill, under the leadership of the inventor Per Gustafsson. Gustafsson's experience with water-powered hammers goes back to the early 80's when he was engaged in such R&D work at Atlas Copco.

Prototypes of the hammer have been in use in LKAB for almost five years where they have drilled about 500 km in the Malmberget and Kiruna mines. The hammers have also been tested at Kidd Creek mine in Canada with very positive results.

Conventional air-powered in-hole hammers drill much straighter holes than hydraulic top hammers, but their penetration rate is comparatively low. The big advantage of water-powered hammers over air-powered in-hole hammers is the penetration rate, often two to three times that of an air-powered hammer with similar accuracy.

In order to reap the full advantages of the new water hammer, it must part of a total drilling system that is designed for accuracy and high productivity. The Atlas Copco Simba W469 is this system. It is a drill jumbo based on the well-known Simba production rig and developed through close cooperation between LKAB and Atlas Copco.

The three principal goals set for the new rig were to:

* Improve drilling precision

* Reduce capital and drilling costs

* Increase mechanical availibity

The Simba W469 is remote controlled and has the capacity to drill automatically 10 holes of 115-mm-dia and with a length of up to 55 m. The accuracy demands are very high. The maximum set-up error is 0.5 [degrees] and the angular precision of the fan rings must be 0.1 [degree]. The maximum hole-end deviation is no more than 1.5%. The rig is set up and aligned on a laser beam.

Figure 10 shows the design of the new rig. It is single-boomed in order to maximize reliability and availability (if boom availability is 90%, a twin-boom machine will have 81% availability, which is unacceptable). In order to achieve straight holes, extension tubes rather than rods are essential. The tube-carousel is set back from the boom in order not to interfere with accurate boom positioning and to keep the tubes clear of drill cuttings running out of the hole.

After drilling 55 m the bits will need resharpening. Thus provision will be made to mount extra hammer/bit units on the carousel so that they can be automatically changed, just like the tubes, as drilling proceeds from hole to hole in the fan.

Eventually it is planned that one operator will control three drills from the central control room on 775-m level mentioned above in connection with the remote control loading and haulage on the 1045-m level. In the initial stages of application of the Simba W469s, the operator will work from a mobile control vehicle parked in the section.

In order to maximize the operating time of the rigs, a maintenance schedule comparable to that of the aircraft industry is envisaged. The cost breakdown for operating such a rig is estimated as:
Maintenance                         36%
Energy                               4%
Drill string                        18%
Wassara drill                       17%
Operator                             8%
Capital costs                       17%

Total                              100%


The first of the new rigs will be delivered to LKAB towards the end of this year and a further nine to 11 units will be delivered from 1995 through to 1998. The total value of this order is about SEK 80M. From 1998 the new rigs are expected to meet the full production drilling requirements of 30M mt/yr ore at the Kiruna and Malberget mines.

Raising, Bolting, Scaling

In-hole hammers are also being used in a new raising technique which has been developed by the mining equipment company, Kiruna Mine Tech. Traditionally Alimak raise climbers have been used to mine the slot raises for blasting stopes in Kiruna. A few years ago the Kiruna Raise Drill method was introduced to supplement Alimak raising for slots.

A 10-in.-dia pilot hole is drilled first. After drilling the pilot hole, the Kiruna Drill is mounted on the rig. The Kiruna Drill consists of two or alternatively three Ingersoll-Rand IR SF6 in-hole hammers mounted together. These are equipped with 8-in. dia bits which in combination give a 680-mm-dia hole. Penetration rate at Kiruna has varied from 1m/hr in hard waste rock to 1.8 m/hr in ore. A special container is placed against the hole collar to catch drill cuttings and water which are led away through a hose.

After drilling 5-8 m, if needed, a special guide is placed in the drill string to keep it straight. Using the guide, inclined holes angled at up to 45 [degrees] can be drilled. The guide is not normally needed for vertical holes.

After drilling the 680-mm hole, blastholes are drilled in a special pattern around it and the complete raise is blasted out in one round using delays. Raises of up to 40-m long have been mined by this method at Kiruna. The limit is set by the blasting technique. The drilling is only limited by the carrying capacity of the boom. It is reported that slot raises of 18 to 35 m in length can be completed in half to one-third the time required to mine a slot with a raise climber. In addition, the miners are not exposed to the dangers and discomforts of being in the raise themselves.

Kiruna uses about 20 km/yr cable bolts for rock reinforcement. The average hole length is 7 m and the diameter is 64 mm, but in some areas cable bolts up to 40 m long are used. Swedengineers Minetech AB recently delivered a new one-man operated cable-bolter to the mine. The new unit is mounted on a truck chassis equipped with a hydraulic crane. All functions are hydraulically operated by remote control so that the operator can stand under safe roof. The cable bolter is fitted at the end of the crane. A clamping device at the bolter head holds the cable and prevents it falling out of the hole. The cable cutter and injection nozzle are also mounted at the bolter head. In the so-called Kiruna method, the cable is inserted first and grouting takes place afterwards. The special 26-mm-dia bolting cable is equipped with an air-bleed tube in the middle so that the hole can be grouted after the cable is inserted.

LKAB produces more than iron-ore products. Readers will realize that its engineers and miners have invented, or helped develop, many new and ingenious mining machines and methods.

The Swedengineers company mentioned above in connection with the rockbolter was actually formed in 1982 by people connected with LKAB who took over the sales of innovations developed in the mines. Most of these innovations were connected with rock reinforcement methods such as shotcreting, rockbolting, reinforcement nets, and cable bolting.

In order to operate safely, rock must not only be reinforced, but loose rock on the surface of openings must be safely scaled off. LKAB, in cooperation with a local specialized manufacturer, Bask, has developed one of the most advanced scaling methods in the world, which has greatly reduced accidents during scaling. The Bask mechanized scalers have a specially designed scaling boom, a safety cabin with data information display, and are mounted on diesel- or gasoline driven carriers. LKAB uses five Bask mechanized scalers at Kiruna and Malmberget; it has ordered three more.

Remote-Control, Automated LHDs

Possibly the most futuristic component of the future production system is the planned use of remote controlled and automated LHDs to muck ore from the drawpoints of the sublevel cave stopes and tram it to the ore passes. Operators in the control center of 775-m level will each be in charge of up to three LHDs. The operators load and unload the machines via remote control at the drawpoints and dumping points, but the LHDs will travel under automatic control between the two points.

The specifications for the LHD's are for electric-powered machines operating with a supply voltage of 1,000V. They must have an independent operating range of at least 350 m. The scoop capacity should be at least 8.5 [m.sup.3] to give an average scoop load of 25 mt. Some eight to 10 machines will be required.

Kiruna has done much test work on the remote control/automation of LHDs. Figure 12 shows the arrangement used with a Tamrock Toro loader where a buried control wire in the roadway allows the loader's position to be determined. The LHD's position is fed into a computer and compared to a pre-determined route/speed pattern. The appropriate adjustment-command signal is radioed to the unit's control receiver and converted into the required steering/speed adjustment. Video monitors allow the remote operator to take over, seeing what is happening in loading.

No decision has yet been taken on what the final remote control/automation system for the LHDs should be. It may be that a simpler navigation system, e.g. having the LHD "visually" follow a white marker line on the roof could be the best practical solution.

SAK 2000--The Concentrator and Pellet Plant

Half of LKAB's future-oriented investment is being made underground. The other half is being made above ground in new ore-processing facilities. In December 1992 LKAB decided to increase pelletizing capacity at Kiruna by 4M mt/yr. This meant that a new concentrator would also have to be built. This expansion of processing capacity constitutes the SAK 2000 project. A two-year time frame was envisaged from decision to start-up. This has been adhered to. The new concentrator is gearing up now for test operation, and commercial pellet production will start at the beginning of 1995 with full production planned for May 1995.

The first processing step for the Kiruna ore is underground primary crushing to -100 mm. On surface, the ore may go to the sorting plant, or directly to a concentrator.

The Kiruna concentrators apply a series of magnetic separation steps to produce a very high grade magnetite concentrate as pellet-plant feed. In addition the concentrators have a flotation section for the reduction of phosphorus content in the ore if necessary.

The phosphorus content of the Kiruna orebody is declining with increasing depth, but the market for high-phosphorus products is declining even faster. LKAB has only two customers left buying this grade of material.

The strategy is to supply mainly belt-separated high-phosphorus ore at -100-mm direct from the mine to the new concentrator (KA2) which will operate with the phosphorus-reduction flotation step, while the existing KA1 concentrator will be fed with low-phosphorus ore and operate without the flotation step. If necessary, the KA1 can also operate with flotation. In this manner, more high-phosphorus ore can be used as raw material for pellets--to meet the increasing demand for this product while compensating for the reduction in demand for high-phosphorus products. Mill feed to KA2 will be approximately 58-59% Fe and 1% P. Final concentrate should be around 71% Fe, 0.025% P, and 0.5% Si.

Autogenous Grinding Mills

The KA2 concentrator has two parallel lines with a combined capacity of 700-800 mt/hr throughput. In broad outline, the new concentrator flowsheet is similar to that of the existing plant. The single big difference is in the grinding step. KA2 employs primary autogenous grinding while KA1 has primary ball mills. This is LKAB's first application of AG. Secondary grinding is KA2, as in KA1, is in pebble mills.

All of the grinding mills have been supplied by Morgardshammar. In addition to the two AG mills and two pebble mills, Morgardshammar also supplied a 3.5-m-dia x 4.8-m-long ball-mill which is used for the grinding of additives such as dolomite or olivine which are required for the pellet mix.

The two primary AG mills are 6.5-m-dia x 5.3-m long. They are shell-supported on hydrostatic shoe-bearings and are driven through gear boxes by 1,000 rpm, 4.5 MW output electric motors. The discharge trommel recovers the 10-35 mm product as pebbles for the secondary mills. Excess coarse material is crushed in Morgardshammar cone crushers in the mill circuit and returned to the mill.

Mill liners are supplied by Skega and Trellex. Comparative liner tests are being conducted by using Skega liners on one grinding line and Trellex liners on the other. Skega has had an ongoing technical development cooperation program with LKAB for many years. Teams from the supplier and mining company meet regularly for technical discussions. Three areas of importance for the SAK 2000 project have been design of mill liners, pebble grates, and trommels. All five mill-discharge trommels in KA2 were supplied by Skega.

Trellex magnetic liners are used on three of the pebble mills in the old concentrator are being used on one of the pebble mills in the new plant.

As the main supplier of mill liners for SAK 2000, Skega became involved at an early stage of the project with specific recommendations on liner design. Liner design is critical from the point of view of life, mill economy, maintenance schedules, and liner replacement (drilling patterns).

Undersize from the AG-mill discharge trommels is pumped to a Denver-Sala spiral classifier from where underflow is returned to the AG mill and overflow goes to primary magnetic separation.

Magnetic Separation and Flotation

The Denver-Sala magnetic separators in the new concentrator have been upscaled to 3-m long compared to the 1.8-m long x 1.2-m-dia units in the KA1 concentrator. The magnetic concentrate from the separators goes for secondary grinding in the pebble mills, and the tailing goes to the new tailing thickener.

The coarse product from the 6.5-m-dia x 8.5-m long pebble mills is returned to the primary AG mills, the fine product is classified in a bank of Larox hydrocyclones. Cyclone underflow passes through a Denver-Sala magnetic separator. Concentrate is returned to the pebble mill while the tailing goes to the tailing thickener.

Overflow from the pebble-mill cyclones goes to the two-stage, four-group magnetic pre-separator section which is designed to remove as much phosphorus and silica (non magnetics) as possible ahead of dephosphorizing flotation.

The apatite (phosphorus) mineral is removed from the flotation feed in banks of Outokumpu 40 [m.sup.3] flotation cells using fatty-acid reagents. Retention time is about 20 min. The apatite concentrate is cleaned magnetically before going to the tailing thickener. The non-floating magnetite concentrate goes for final magnetic separation in another two-stage, four group separator section.

A new Denver-Sala 65-m-dia thickener has been built for the tailings from the new concentrator and pellet plants. At a later stage it will also handle tailings from the KA1 concentrator. Approximately 200 [m.sup.3]/min water will pass through the new thickener. Because the thickener receives pellet plant tailing, the underflow is passed through a magnetic control separator before going to the tailings pond. The magnetite concentrate recovered is returned to the pebble mills.

A new control room has been built from which both concentrators are now controlled.

The entire process instrumentation, monitoring, and process control systems to control the concentrators and pelletizing plants were supplied by Tillquist Process AB, the Swedish representative of Hartmann & Braun of Germany. The whole system comprises the CIM/21 process data management system for 10K signals plus two Contronic P process control systems with a total of 7,500 signals. In both new Contronic P systems, four control stations in total control the process and 20 process stations perform comprehensive monitoring and control tasks. CIM/21 collects and evaluates data systematically for calculations, production control, and analyses of process interdependences. CIM/21 permits the representation and comparison of this data in graphic or tabular manner on workstation or PC screens. Process, lab, or production data can be combined freely. A playback function allows the representation of historical processes at selectable speed.

Besides the dynamical process variables from all process systems, the process graphics also display data from Oracle-based applications. The data is displayed in real-time in selected time windows. The report tools of the relational databases are available for logging.

Revamping Hoisting System

The opening of the new haulage level means that Kiruna will have to change from single-stage to double-stage hoisting. The existing hoisting system, installed about 25 years ago, comprised eight hoists lifting ore from a depth of 802 m through the vertical, surface shafts. The system incorporated the then most modern technology, and was full automatic. It was delivered by ASEA (now ABB). ABB has also been entrusted with delivering the new hoisting system.

The changeover period from the 775-m to the 1045-m haulage level will extend over a total period of about six years. Two of the present eight hoists will be moved underground. These, and two new hoists, will be installed for the subvertical hoisting. The changeover must be made without any interruption to production--which indeed must even be increased over the period.

The six hoists in the surface headframe will all be modernized before the subvertical shafts are completed. Then the two new and two modernized hoists will be installed underground. Production will then start from the 1045-m level. On average, one hoist at a time is out of operation undergoing modernization.

The modernization optimizes the hoisting cycle by applying the latest in hoist drive technology, control systems, man-machine communications (MMC), and diagnostics. By increasing the mean time between failures and decreasing the mean time to repair, the production rate will be increased by 12.5% and the availability by almost 100%. This was verified after completion of the first hoist revamp, and study of its performance operating 24 hr/d over several months.

The four subvertical hoists will lift the ore 355 m to the transfer station which utilizes the bins and conveyors of the existing 775-m haulage level. There the surface-shaft skips are loaded for the 802 m lift to the headframe. The capacity of the system is 26M mt/yr.

On the mechanical side, hoist modernization includes:

* Replacement of brake position limit-switches by analog position transducers;

* New brake hydraulic station-improved functionality/diagnostics;

* Installation of constant retardation control at emergency braking;

* New oil-lubrication system and improve seals for bearings;

* New calibration system for load cell under the measuring pocket;

* Broken rope-wire detector

In the new calibration system for the measuring-pocket load cell, the Pressductor load-cell is calibrated in situ without the need for a known weight. In the past, verification of the "as installed" accuracy of such load cells has been a general problem.

The modernization of the hoist electrics includes:

* New, fully digital microprocessor-controlled thyristor convertors with fewer, more powerful, thyristors (one per branch versus 10 in the past) and built-in data logger for diagnostics with first-up indication and post-mortem review;

* New microprocessor-based hoist-control system ABB Master 200/1 including:

- Closed-loop position and speed control, automatic compensation for friction liner wear;

- Digital hoist monitoring;

- Loading and dumping sequences integrated into hoist-control system;

- Fiber-optic cables for data transmission between the loading level and the hoist-control microprocessor as well as to the central hoist-monitoring system;

- Brake-disc temperature monitoring, with hoisting speed limited to 10 m/sec at a preset disc-temperature value;

- Magnetic marks on the ropes to replace limit switches in the retardation zones;

- Ore-flow monitor to detect skip emptied at the dumping station;

- Semi-automatic tests of safety devices (statutory tests)

To meet today's requirement for reports and trend curves on production, availability, and other statistics, and to verify statutory test results, etc., a microprocessor-based ABB Advent system with color graphics, keyboards, and printers was selected.

The man-machine-communication system is built on the principle of "information by exception". The important information such as alarms appear in red, while symbols for hoist system parts appear on the screen in pale or non-dominant colors.
New Kiruna Two-Stage Hoisting System

                          Surface Shafts             Subvertical Shafts

Number of Hoists     Two            Four          Three          One
Capacity             1,025 mt/hr    856 mt/hr     1,344 mt/hr    1,680 mt/hr
Motor power          4,300 kW       4,300 kW      4,300 kW       5,600 kW
Hoist type           Double         Single        Double         Double
30 mt
Conveyance weight    25.1 mt        32 mt         37.4 mt        44.1 mt
Hoisting depth       802 m          802 m         355 m          355 m
Hoisting speed       17 m/sec       17 m/sec      10 m/sec       10 m/sec
Pulley dia           3.25 m         3.25 m        3.25 m         3.25 m
Head ropes           Four           Six           Four           Four
Rope dia             40 mm          40 mm         40 mm          40 mm
Rope strand          Triangular     Triangular    Triangular     Triangular


Lake Ore

Although there is only some 110M mt ore reserve left above the 775-m haulage level within the present mining limits, there is the possibility for additional ore outside those limits. The northern part of the Kiruna orebody lies under a lake, Luossajarvi (the salmon lake in the Lappish language). The existence of the lake sterilizes ore in the northern part of the deposit. If the ore quality here is payable, and if the lake were to be partially drained, then around 100M mt additional ore could be mined.

LKAB has conducted extensive research into the possible consequences of the drainage. The findings of this research has been summarized in an environmental report. The company has applied to the various permittng authorities for permission to drain the southern part of Luossajarvi to gain safe access to the underlying ore. The project would affect about one-fifth of the 200-ha lake. A final decision on LKAB's application is still pending.

Wassara Water Drill

The Wassara drill combines the advantages of top and in-hole hammers. It uses normal mine water boosted by a separate pump to a pressure of around 180 bar. The mine water passes through a 100-micron filter to meet the requirements of the 110-kW piston pump. The latter is a standard triplex piston pump mounted on trailer (with electrics, hose connections, etc.). Standard 1.25-1.5-in. hydraulic hose is used. Water consumption varies according to wear; the expected level for the rig at Kiruna is 280 l/min at 180 bar.

The water hammer works and looks like an air hammer. The bits used are standard Cop 42 type. The penetration rate drilling 115-mm holes in hard rock (145 MPa or 21K lb/[in.sup.2]) is 45-90 cm/min which two to three times higher than conventional hammers. In Canadian mine test, the number of feet drilled per shift including downtime was doubled.

The water hammer requires service about twice as often in terms of meters drilled as an air hammer. The total life of a water hammer is 3-4 km hole drilled, compared to about 5 km hole drilled for an air hammer. There is good hole cleaning in bad ground both when drilling up or down. The good flushing reduces the risk of getting stuck and makes the use of low-clearance stabilizers for very straight holes possible.

The hammer uses four to six times less energy per drilled foot than an air drill. In the Canadian test the electrical power cost was nearly halved (air-system leakage excluded). There is no air-carried dust, or oil-fog in the air. In addition, since no oil is added to the flushing water, there is improved environmental water quality.

Sorting Plant

The underground primary crushers reduce the ore to -100 mm before it is hoisted to the sorting plant. By a discriminating process of quality sampling, the ore is classified underground according to phosphorus and alkali content. In the sorting plant the different ore types are treated in specific circuits incorporating fine crushing, screening, magnetic separation, and dewatering. About 15-20% of the raw feed to the sorting plant is rejected as waste by the Denver-Sala magnetic separators. The main product of the sorting plant is concentrator feed. However, it also delivers finished product for the market such as low-phosphorus sinter fines and high-phosphorus lump ore and fines.

Although the sorting plant as such does not figure in the SAK 2000 expansion and modernization project, important improvements and innovations have been introduced here in the past three of four years. The goals have been to maximize fine crushing to reduce the amount of grinding required downstream, and to move to open-circuit crushing to reduce the amount of material re-circulating on conveyors and make the system less complicated.

Since grinding consumes four times as much energy as crushing, the benefits of increased fine crushing are obvious. To achieve this, LKAB installed two Nordberg G 415 cone crushers, each with a rated capacity of 10K mt/d. One unit is operated continuously while the other is on permanent standby. Crushing 3.3-10 mm material, the output is as much as 60% -3.3 mm. The capacity of the crushers has also been better than expected, roughly 12K mt/d or 500 mt/hr, giving the sorting plant a capacity increase of 0.5M mt/yr ore.

The crushers are equipped with an electronic Lokoset automatic control system which optimized performance by monitoring and controlling setting, power draw, and hydraulic pressure.

Other new equipment in the sorting plant includes two Denver-Sala magnetic cobbing separators with a sector magnet system designed to treat large lumps of ore. Extensive use is made of Mogensen sizers/divergators for screening in the sorting plant and concentrator.

The sorting plant already supplies feed for two concentrators and their associated pellet plants--the existing Kiruna plants and those at Svappavaara. In future it will be able to supply feed to the new Kiruna concentrator as well, although initial plans for KA2 are for it to be fed with ore direct from the mine. Sorting plant capacity is not a problem.

Suppliers of Major Equipment for New Concentrator

Grinding mills Mill motors Mill liners Overhead cranes Crushers Thickener Conveyors Screw classifiers Cyclones Pinch valves Tailing/slurry pumps Water pumps Vibratory feeders Pebble screens Magnetic separators Morgardshammar AEG Skega, Trellex Munck Morgardshammar Denver-Sala KGS/Roxon Denver-Sala KGS/Larox KGS/Larox Denver-Sala Ahlstrom IFE Mogensen Sala

Grate-Kiln Pellet Plant

LKAB selected the Allis Mineral Systems Grate-Kiln process for its new pellet plant at Kiruna, KK3. This is the third Grate-Kiln plant installed by LKAB. The new plant differs in some ways from the very similar KK2 Kiruna pellet plant which was built in 1981. The magnetite slurry feed in the new plant is dewatered in Denver-Sala pressure filters, instead of on vacuum filters, the new plant has fewer, but larger-capacity, balling circuits, and the grate and cooler have larger areas than those in the KK2 plant. Figure 15 shows the KK3 pellet plant flowsheet.

The KK2 plant had a design capacity of 3.5M mt/yr pellets, but it is now operating at 4M mt/yr. The KK3 plant has a nominal capacity of 4M mt/yr so it is likely that the actual production could be pushed up towards 5M mt/yr if necessary.

Allis Mineral Systems, Pyro Systems Division in Waukesha, Wisconsin received an order in early 1992 for the design, engineering, and supply of the iron-ore pelletizing plant. Allis Mineral Systems is a member of the Swedish Svedala Industries group. The main components of the approximately $40M Grate-Kiln plant are a 60-m long by 4.6-m wide traveling grate for pellet drying and preheating, a 43-m long by 6.7-m-dia induration kiln, and a 3.6-m wide by 22-m-dia annular cooler.

The feed for the pellet plant is magnetite concentrate from the KA2 concentrator and additives such as dolomite or olivine for different pellet types. The various pellet types are manufactured in campaigns.

The additives are ground wet in one stage in a ball mill, spiral classifier, hydrocyclone circuit in the concentrator. The ground additives are fed to a agitated slurry make-up tank in the pellet plant. From there they are metered into the main magnetite slurry tank. The additive content of the magnetite slurry is about 3%.

The main magnetite slurry tank in the pellet plant is a concrete tank 18.3-m-dia and 16.7-m high which holds 4,000 [m.sup.3] slurry at 60-70% solids and an average maximum density of 2,300 kg/[m.sup.3]. The slurry must be agitated to keep a uniform density throughout the tank. That takes some stirring. Oy Japrotek AB designed especially sturdy and rigid agitation systems for the main tank and make-up tank. In the main tank the rubber-lined, four-blade hydrofoil-type impeller has a diameter of 5 m. The shaft is 500-mm-dia and the electrical drive is 160 kW. The specially designed drive gear allows the agitator to start up in the slurry from standstill.

The make-up tank is steel, 7-m-dia and 8.4-m high, and has a 3-m-dia impeller mounted on a 200-mm-dia shaft driven by a-30 kW motor.

Large Pressure Filters

The slurry is pumped to the filter section where it is dewatered in four Denver-Sala air pressure filters. The capacity of the four 50-chamber filters (250 mt/hr dry product each) is more than adequate for the designed plant feed, three would handle it, so security is built in to the system by always having a standby unit. By using pressure filters rather than vacuum filters as used in the KK1 plant, the dewatering is more precisely controlled thus avoiding quality variations. The moisture content of the slurry is reduced from 30-35% to 8.5-9%. The moisture content of the product can be controlled to +/- 0.1%.

The filters dewater the slurry in batches of 30 mt at a time. The dewatering cycle is about 6 min.

The air for the pressure filters, and for all other process requirements too, is supplied by a new compressor station. The three Ingersoll Rand Centac compressors probably constitute the biggest compressor installation made in Scandinavia in the past 20 years. Two compressors run constantly (8,760 hr/yr) while the third is on standby. Each compressor delivers 250 [m.sup.3]/min.

The dewatered concentrate is mixed with bentonite binder and conveyed to the balling section day bins. The green pellets are formed in four variable-inclination, variable-speed Mexor balling drums. With a diameter of 5 m and a length of 13 m each, these are probably the largest balling drums in the world. The older KK1 plant has six, smaller balling drums. Throughout the new plant the idea has been to use, where possible, fewer, larger units in each step to reduce the complexity and the number of conveyors required.

Each drum has a capacity of 300 mt/hr. Once again, the capacity of the system is such that three drums are adequate and one can be kept on standby.

The green balls are formed at 10-12 mm. Undersize balls are returned to the balling drums and oversize balls are crushed and returned to the day bins.

The adjustable-gap roller screens for ball sizing incorporate new LKAB design features which simplify screen changing. What took two shifts in the old plant can be accomplished in a few minutes in the new one.

Firing the Pellets

Correctly sized balls are conveyed to the sintering section where a feeder belt distributes them evenly onto a roller screen from where they are unloaded onto the grate. Pellets pass through four zones of drying and preheating on the grate to insure that moisture is driven off in a controlled manner and that cracking does not occur.

In the first stage of drying, Up-Draught Drying (UDD), heated air from the last stage of the cooler is used. This is followed by Down-Draught Drying (DDD). The partly dried pellets then pass into the Tempered Pre-Heat zone (TPH) where their temperature is further raised by hot down-draught gases, and finally into the Pre-Heat (PH) zone where they are heated by gases exhausting directly from the kiln.

The pre-heated pellets pass into the 33.5-m long refractory-lined kiln where they are sintered. By keeping the pellets at a constant temperature as they travel through the last 20 m of the kiln, a high pellet quality is insured.

The fired pellets are then cooled in three zones of an annular cooler. The cooling air is supplied from underneath, making it possible to maintain a relatively low temperature at the grate plates of the cooler. The quantity of cooling air supplied to each zone is calculated so as to produce the correct amount and temperature of air for the kiln and grate zones. Heated air which is not needed for the grate is diverted to a heat recycle system.

The energy in hot gases from the process is recuperated in an Ahlstrom waste-heat boiler plant. The gases are cleaned, de-sulphurized, and filtered before being released to the atmosphere through the 50-m stack. Due to control measures in the process and efficient cleaning systems, the environmental impact of the two pellet plants will be less than that of the original single plant.

Coal is the principal fuel for both plants although oil can be burned if necessary. Kiruna is located north of the Arctic circle, and the coal comes from--Australia. The new pellet plant's gas cleaning facilities mean that lower-quality less-expensive coal, e.g. from Poland, could be used if desired.
Suppliers of Major Equipment for New Pellet Plant

Kiln                         Allis Mineral Systems
Pressure Filters             Sala
Gas cleaning                 Novenco
Waste heat boiler            Ahlstrom
Balling drums                Mexor
Drive equipment              ABB Drives
Overhead cranes              Munk
Mixer agitators              Japrotek
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Title Annotation:includes related articles
Author:Wyllie, Robert J.M.
Publication:E&MJ - Engineering & Mining Journal
Article Type:Cover Story
Date:Oct 1, 1994
Words:10187
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