Quality products made from oversize aggregates
Oversize aggregates are a major challenge for many operators. The high-quality aggregates are often stored in a space-consuming way or even disposed of by backfilling at a considerable loss. Nevertheless, even large quantities can be processed with a manageable amount of engineering effort thus achieving significantly higher added value. This is put into practice at Plant 2 in Saaldorf of the German Austrian Moosleitner Group, where an SBM vertical impact crusher model V8 crushes oversize aggregates with grain sizes 4/8 and 16/32 mm to produce high-quality crushed stone fines 0/4 as an additive to washed concrete sand 0/4.
With around 600,000 tons of gravel and a further 120,000 tons of certified recycled construction materials, Plant 2 in Saaldorf is the largest facility of the German Austrian Moosleitner Group. Two gravel quarries, three concrete plants, and several quarries, recycling facilities, and landfill sites, either operated independently or in cooperation with partners, belong to the raw material, building material, and environmental sector in both countries. With a total of over 200 employees, this long-established family business also operates in the fields of earthworks, civil engineering, road construction, and demolition across national borders.
Since the beginning of 2023, road construction materials in the Saaldorf plant have been processed by a track-mobile SBM impact crusher type REMAX 400 (0/400 to certified grain sizes 0/16, 0/22, 0/32, 0/63 mm). The aggregates for two of the company's own concrete factories and other concrete factories in the region are supplied by a stationary 300 t/h gravel washing plant. From 0/100 feed material, the multi-stage screening plant produces high-quality 0/4, 4/8, 8/16-, and 16/32-mm grain sizes with an average annual output of around 400,000 tons. Already since 2010, some of the coarse 32/70 grain size and other surplus materials have been processed into chippings and crushed stone fines, primarily for asphalt production, by an 80 t/h cone crusher located directly next to the gravel washing plant.
Since the end of 2023, an SBM V8 vertical impact crusher has been solving this problem: Particularly developed to efficiently produce sand this compact crusher was integrated into the existing crushing plant with feed hopper, feed conveyor and double-deck screen. With an output of 60–70 tons per hour, the SBM V8 crusher now processes oversize aggregates 4/8 and 16/32 to high-quality 0/4 crushed stone fines which can be directly mixed with washed 0/4 concrete sand without further processing thanks to the distinctive cubic grain form and precisely adjustable grain size distribution. Depending on the results of the corresponding laboratory tests, between 10 and 20% are added, whereby the targeted control of the properties of the crushed grain sizes also allows to optimise the quality of the 0/4 delivered grain sizes by correcting the grain size distribution.
‘Our solution with the SBM V8 vertical shaft impact crusher has fulfilled all expectations,’ explains Senior Manager Matthias Moosleitner, who runs the Moosleitner Group together with his wife Martina and son Mathias. The evaluation phase lasted a good six months including on-site assessments of various already implemented solutions for oversize aggregates. Different tertiary crushers were assessed not only in terms of their crushing characteristics – the focus was on finding the economically best technical integration into the existing gravel washing plant.
The aim was to achieve a final product that was as compatible as possible with the washed concrete sand in Saaldorf in terms of grain form and grain size distribution. The decision was eventually taken in favour of the SBM V8 vertical impact crusher: Just like larger V-crushers with outputs of up to 160 t/h, it was particularly developed to produce sand and to make poorly shaped fines more cubic. With vertical feeding (feed sizes 35/40 mm), the patented SBM inlet control and the electric drive with frequency converter-controlled rotor speed as the key control parameter, SBM vertical shaft impact crushers can be integrated into existing plants very easily and simply. In the standard design, crushing takes place in the material cushion or ‘“material bed”' thanks to the high energy input of the especially developed high-speed rotors. The SBM inlet control with filling level monitoring at the material hopper minimises the pull effect even at constantly high rotor speeds, thereby ensuring that the material bed is maintained and guaranteeing uniform quality, low wear costs, and low dust emissions under full or partial load.
The SBM V8 vertical impact crusher has around 10 tons and is an easily relocatable unit in a steel structure with a surrounding maintenance platform. Therefore, it was very simple to integrate it into the existing installation in Saaldorf. The crusher is fed by wheel loader via a pivoting conveyor belt; the crushed material is transported to the double-deck screen by oversize material return conveyor belt to the feed hopper; and there are wide conveyor belts for the final grain sizes 5/8 mm chippings and 0/4 mm crushed stone fines.
![[Translate to Englisch:] SBM Vertikalbrecher V8](https://www.sbm-mp.at/fileadmin/_processed_/a/2/csm_SBM_Moosleitner_V8_3_29f82533ca.jpg)
After some 200 operating hours, Matthias Moosleitner is very positive: ‘We were able to integrate the SBM V8 into our crushing plant without any problems. It delivers consistently high-quality products, both in terms of grain form and grain size distribution, which is essential for the controlled addition to our washed concrete sand.’ The production output is also excellent: ‘With 60 to 70 t/h, it easily equals the sand output of our washing plant, and its independent operation gives us complete flexibility to process any oversize aggregates at hand.’
Plant Manager Peter Gastberger also emphasises the advantages of the SBMM vertical impact crusher: ‘With V8, we can precisely adjust the properties of the crushed material 0/4 mm to the washed material. Currently we are working with three pre-settings in the crusher control system taking into account the usual variability in the washed sand.’ The SBM V8 crusher also excels in operation and maintenance: ‘Even under full load, the crusher operates quietly, with low vibration and virtually no dust thanks to the inlet control. Especially in direct comparison with our cone crusher, wear is extremely low, which minimises maintenance and significantly increases the availability of the V8 due to the electric drive concept.’ Take winter operation, for example: While the cone crusher, with its some 300 l of gearbox respectively hydraulic oil, requires a considerable lead time at low temperatures, the SBM crusher V8 is ready for operation in no time at all thanks to its grease lubrication and only 10 l of hydraulic volume necessary for the gap adjustment.
