Sizes of the primary and secondary steps
|CST 1200||1,000||1.4 - 2.0||80||100 - 200|
|CST 800-10 SR-WB||800||1,000||8 - 22||50 - 150|
Composition of the feed material
|Primary crushing step||- milling material|
- asphalt clods up to 1.9 m edge length and a thickness of
|Secondary crushing step||- 0/80 mm|
- coarse grain of up to 120 mm
|Crushing gap||adjustable||Flexible adjustment on the control system during production in order to run different granulation|
|Overfilling protection||integrated||In case of feeding too large grain the hydraulic adjustment of the roll is used in order to pull in the coarse material|
|Overload protection||integrated||Autonomous draw-back of the roller and automatic return into the pre-adjusted gap width|
|Reversing operation||automated||Blockage is removed independently|
|Crushing tools||Quick-Change-System||Exchange of the complete roll in no time|
|Control system||Machine is fully automated||Machine and process can be supervised and adjusted by means of an operating panel. Feed and withdraw systems can be integrated in the control system|
How to get a high amount of usable granulate from clods and milling material
In order to achieve such a result, a primary crusher crushes the asphalt to be extracted to a size of < 100 mm in a primary crushing step. In order to be able to even cope with bulky chunk sizes and large edge lengths the crushing tool was manufactured in a way that direct draw-in of the feed material by means of large digging teeth is ensured. At low circumferential speed the teeth grab into the material so that it is already pre-crushed in a gentle and low-wear way. Clods and plates with edge lengths of up to 1.8 m and thickness of up to 400 mm are processed. Particles below the defined target granulation are being discharged over a sieving grate before they reach the crushing unit. By means of this concept it is possible to push through an amount of 150 t/ h while the amount of large clods in the feed material can be up to 50%.
The secondary crushing step takes up the complete material from the primary crusher and crushes only those grain sizes which are larger than the target granulation. The double roll system is characterized by an innovative tooth technology which is causal for a high crushing ratio. This process is convincing because naturally existing predetermined breaking points in the old asphalt are utilized. This means that pressure leads to a precise separation exactly between stone grain and binder filling. In this way, reliable granulations of < 11 to < 22 mm can be produced. Due to limited crushing space geometry the amount of oversized grain is less than 1%.
The result counts
Sieving analyses from extracted samples have revealed that granulations 0/22 from asphalt clod material only contained sand portions of 12% and less than 2% dust. The grain form of the stone fraction regained from this procedure is cubical. The largely separated bitumen binder concentrates in the form of adhesions on single stones. These results are proving a very gentle processing of the old asphalt. Especially the low amount of sand shows that the original stone matrix in its structure is almost complete and without undesired additional sand and dust particles in the target grain due to an overload of stress are found. Even for bitumen there is an ideal separation so that it can be used again as an important valuable substance.
Safe operation with high performances
Both crushers have a hydraulic overload protection in order to automatically remove disturbing material from the crushing space without damage of the machine. In order to immediately react upon changing material characteristics in the feed material, also the crushing gap in both crushing steps can individually be adjusted by means of the control panel during the crushing process. The application of a subsequent sieving unit is possible for example in order to lead back oversized grain to the secondary crusher.
Depending on the needs of the operator, the roll crushing unit can be either a track mobile or a wheeled mobile crushing unit. The crushers can serve as an additional system in the processing of asphalt in stationary recycling plants as well.
Depending on the machine size the crushers achieve performances of up to 300 t/h. In order to ensure an efficient operation of the unit, the control system takes over the optimum feed. In the knowledge around the user demands regarding the availability, all CST machines have been equipped with a quick-change system with which the rolls can be exchanged in no time.