Keestrack optimizes electric drive technology in Norwegian quarries

08 November 2019

Last October Keestrack’s distributor Fredheim Maskin AS organized their 10th demo days. At their open days, they open their offices, warehouse and service centre to the public. A shuttle service to a nearby quarry was organised to showcased Keestrack’s solutions for modern aggregate production in Norwegian quarries.

Keestrack offers today the most versatile range of hybrid and plug-in solutions in mobile processing technology for quarrying and recycling applications. This applies to the complete product range, from screening plants and stockpile conveyors to mobile track-mounted crushing solutions of all relevant technologies and for all production capacities.

The Norwegian market

Natural stone is Norway’s biggest export product in volume. Only oil is a bigger export product when expressed in value. As the global demand for aggregates is rising the demand is also rising in the Nordic countries. Fredheim sells and services Keestrack track mobile crushing and screening equipment and advises their customers on their specific needs. For most quarry applications Fredheim advises a complete production train on the described specifications of the client. Generally a jaw crusher is used for primary crushing and a cone crusher for producing defined aggregates end products.

Environmental protection & zero-emission production

Norwegian government and the general public is very concerned about their environment. A zero carbon footprint and environmental protection has high priority especially when operating near urban surroundings. This is also one of the reasons Keestrack’s hybrid and electric plug-in systems are popular in Norway. The additional higher investment for the electric drive systems is earned back very quick.

Replacing hydraulic drives on conveyors, screen shafts and crusher drives by electric motors avoid long oil piping with leak-prone hose connections. Thermal problems in operations under extreme conditions are eliminated. With significantly lower oil quantities and extended change intervals the smaller hydraulic systems of Keestrack’s “e”-versions not only save the environment but also real money. In full-electric operation, this also applies to lubricants, filters and other wear parts of the onboard diesel. Less engine hours mean less maintenance and downtime, which has a positive impact on total cost of ownership, as well as the higher value retention. And finally: engine problems on a diesel-hydraulic crusher can stop the whole production or job-site. With a plug-in hybrid machine, a total breakdown can be avoided by providing an external gen-set to ensure the completion of the project without delay.

Ecologic & economic granite processing

On the demo site Fredheim Maskin showed, besides some recycling applications, the production of six end products with a capacity of 200 t/h in granite. The production line was running fully electric via the drop-off engine/genset of the H6e. Also the primary crushing and scalping has been plugged-in to this production process.

The project layout of the Granit processing set-up.

Primary crushing

The newly designed B7e primary jaw crusher is especially designed for quarry applications with a feed size up to 700 mm and a feed capacity up to 600 tons per hour.

The Keestrack B7e is especially designed for quarrying. The 70-tonnes jaw crusher with max. 700 t/h is one of the models, which is only available as full-electric plug-in version.

The heavy range B7e jaw crusher as primary crusher was connected to the K7e scalper via a plug-out connection. The K7e is specially designed for heavy duty scalping of big feed sizes due to its high screen box. With its punched plate top deck of 60 mm and its bottom deck of 25 mm mesh it produced 2 final products 0/20 mm (90t/h), 20/60 mm (95t/h) and an oversize >60 mm (185t/h). The C.S.S. of the B7e was set on 110 mm, the feed capacity at 370 t/h. The 1200 x 830 mm feed opening of the heavy range jaw crusher has automatic hydraulic gap adjustment and is provided with an ultra-sonic sensor to provide optimal feed control resulting in less wear and best product shape possible. The reversible jaw movement can clear blockages easily and the heavy duty flywheel with a diameter of 1300 mm ensures a high inertia. The B7e has a slidable and drop-off hopper for easier maintenance access, and can be transported separately. The B7e is also equipped with a drop-off engine unit.

Keestrack B7e in combination with the K7e scalper for primary crushing and screening.

Production of six defined end-products

For producing six defined granite aggregates products with a production capacity of 200 t/h the following set-up was showcased: An electric feeding hopper on skids, the heavy range Keestrack H6e cone crusher with infeed belt, single deck pre-screen and 3-deck after screen with recirculation belt, followed by a K3e screen. To facilitate stockpiling there were two S1e stackers with automatic swivelling function and one S5e track mobile stacker applied. All the above equipment, including the primary jaw crusher B7e and scalper K7e was fed by the drop-off engine/generator unit of the H6e.

The complete set up for producing six defined granite aggregates products at 200t/h

The electric feeding hopper was loaded by a wheel loader at 200 t/h, via the infeed belt of the H6e it reached the 4,5 m² single deck pre-screen (wire mesh 20 mm), the screened material was stockpiled via the automatic swivelling S1e stacker (0/20mm at 15 t.p.h.) with a stockpile capacity of 700 t. The >20 mm was led into the cone crusher which was set at C.S.S. 20,5 mm, throw 32 mm, via the hanging 3-deck after-screen (top deck square mesh 25 mm, middle deck square mesh 20 mm and bottom deck mesh 8 x 50 mm) the oversize was returned to the cone via the return conveyor, the upper deck fraction was stockpiled on the right side of the H6e via the automated swivelling stacker S1e (16/22 mm) at 43 t.p.h. with a stockpile capacity of ca. 1.900t. The middle deck fraction was stockpiled by the track mounted S5e stacker (11/16 mm) at 43 t.p.h. with a stockpile capacity of 2.500 t. The remaining material was transported via the H6e’s fines conveyor into the K3e screen with the following configuration: Top deck square mesh 8 mm and bottom deck 4 x 200mm. Resulting in 8/11 mm grainsize coming from the left conveyor at 23 t.p.h. at a stockpile of 110 t, 4/8 mm grainsize coming from the right conveyor at 27 t.p.h. with a 120 t stockpile and 0/4 mm grainsize coming from the main conveyor at 49 t.p.h. at a 100 t stockpile.

The new H6e with infeed belt and single deck pre-screen and oversize return conveyor.

Electric power from 1 source

The drop-off unit of the H6e provided all electricity to drive all equipment on site, the advantages of such a drop-off engine unit is it lowers the service costs due to; less dust emissions in the filters, less vibrations, easier and safer maintenance due to working on ground level and lower noise levels at the machine.

The drop-off engine/gen set unit of the H6e of 700 kVA, on the complete right, supplying the primary and secondary production line from electricity.

The gen set of 700 kVA provided the power supply (plug-in) to all machines described above with a total fuel consumption of less than 90 litres an hour. The power needed by machine is calculated at the following ratio: B7e 25 l/h, K7e 8 l/h, H6e 45 l/h, S1e both 1l/h, K3e 5l/h, S5e 5 l/h.

The granite processing production line combined with the primary crushing and screening line showed the huge saving potentials of the Keestrack “e”-version hybrid electric plug-in concept. The gains could be even higher if the complete production line would have been connected to the mains by plug-in. Compared to conventional diesel-hydraulic systems, energy costs can be reduced up to 80%, the noise levels during emission-free plug-in operation by about 30% according to Keestrack.

Thanks to their on-board diesels, Keestrack's modern "e"-versions remain as flexible and highly mobile as conventional technology without having to add a lot of additional transport weight, ± 1000 kg compared to the respective diesel-hydraulic version.

The K3e in front of the H6e, accompanied by two S1e swivelling stackers and a track mobile S5e stacker.

Even the larger hybrid plants can be transported in one piece, without dismantling. This also contributes to short set-up times. The full integration of all electrical system functions are controlled by the intelligent Keestrack plant control. This includes numerous automated routines (eg. sequential start/stop) and the comprehensive monitoring, with bi-directional transmission of machine and production data, via the satellite-based Keestrack-er system.

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