LOESCHE

Selective comminution of concrete waste and recovery of the concrete constituents in a grinding-drying process

1 Vickers hardness values of the individual concrete components

2 Schematic section through the Loesche mill with designation of the individual process sectors

3 Pilot plant mill, LM 3.6/2 with two standard grinding rollers

4 Products of the pilot test series. Left: ground filler, right: liberated concrete aggregate

5 Setting parameters of the pilot plant LM 3.6/2 and effects on the products of the selective comminution process

6 Particles from the coarse ground product, embedded in resin for microscopic examination. Left: light material (-2.5 t/m³, right: heavy material (+ 2.5 t/m³)

7 Concrete granulates. Upper: 2/8 mm after the Loesche process, lower: 4/30 mm, conventional

8 Increase in compressive strength (MPa) after 28 days due to the usage of reclaimed filler compared to the inert additive of 30 weight-% of quartz sand

9 Schematic representation of the process for processing concrete rubble by the Loesche system

10 Flow sheet of a Loesche-system co-grinding plant

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All Loesche

THE BERLIN WALL – is not recycled yet

All Loesche

Using a Loesche VRM, trials were carried out in order to determine the extent to which the constituents of concrete waste could be made suitable by a special recycling process for use as a substitute for the natural rock fraction in components. In this process, the employment of suitable separation equipment played a crucial role.

1 Summary

This article describes a new process for the separate recovery of the components of concrete waste by means of selective comminution in combination with dry separation by density. The process is based on a Loesche roller mill, which liberates the gravel and sand fractions in a non-destructive manner. Post-separation of the coarse fraction using an air jigging machine or dry fluidized bed separation ultimately produces a recyclate of such a good quality that it can be used to completely replace the natural rock fraction. Pilot results of the selective comminution are presented and it...

TEXT Andre Bätz¹, Holger Wulfert¹, Paul Erwerth¹, Andreas Schiffers², Andreas Jungmann², Dirk van Mechelen³
¹Loesche GmbH, Dusseldorf/Germany; ²Cala Aufbereitungstechnik GmbH & Co. KG, Germany; ³Aggregate Consultants bvba, Tisselt/Belgium