Page 38 - HUB-4 Magazine Issue 94

Quarrying
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.
Flexible added value
Due to the natural grain spectrum and the current market
situation, 10,000 to 20,000 tons of oversize material
particularly in the 4/8 and 16/32 mm grain sizes occur in the
plant in Saaldorf per year. On the other hand, there is often a
high demand for high-quality 0/4 concrete sand.
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.
The decision to go with the ‘sand machine’
‘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
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www.hub-4.com Sept/Oct - Issue 94