Recycling Asphalt – An Economic Advantage
Reprocessing reclaimed asphalt not only makes economic sense in a price-sensitive market, it also preserves valuable natural resources. The Benninghoven recycling granulator is a specialized plant designed to meet the demands of the asphalt industry by delivering high levels of production with minimum fines and dust content
Impact and jaw crushers were primarily developed for the reduction of hard materials, such as rock and concrete rubble, where a high-energy input is required for the crushing process. The use of such machines in the recycling of reclaimed asphalt tends to result in fragmentation of the aggregates within the asphalt and the production of a high percentage of fines. To achieve the end-product grading required, large quantities of virgin rock must then be added. In addition, the fine-grained material in the crushed asphalt absorbs large quantities of water, thus resulting in additional cost in the asphalt plant drying process.
In developing an asphalt recycling machine, the main criteria for Benninghoven’s research and development team was to design a highly efficient granulator capable of breaking reclaimed asphalt blocks and planings down to a set recyclable size without reducing the original stone content.
The resulting Benninghoven BRG 2000 recycling granulator is capable of sizing one or two products simultaneously at rates of up to 200 tonnes/h. In its mobile form, the compact unit with its high level of mobility and quick set-up times, is particularly well suited to the economic and efficient handling of small quantities of material.
Principle of operation
The granulator’s primary crusher is fed, by wheel loader, with slabs of reclaimed asphalt measuring up to 1,800mm in length. Hydraulically powered arms press the material on to the single rotating grinding rotor, where the cutting teeth act against the adjustable crusher camber bar to break down the feed material. If the feed material contains iron components, the spring-mounted breaker bar allows the material to pass, without causing damage, for removal by a magnetic separator.
The speed of the milling shaft is controlled electronically and ensures a consistent feed and high production rate regardless of the material type. The resulting material, pre-crushed to around 0–60 mm, is then transferred on to a conveyor belt that feeds a high-capacity, two-deck vibrating screen which delivers two finished products (0–8mm and 8–22mm) ready for stockpiling.
Any oversize material passes to a secondary double-shaft granulator beneath the screen for final reduction. The final size is obtained by variable adjustment of the gap between the granulator rotors, while space-saving recirculation of the re-crushed material to the high-capacity screen ensures that the finished product contains only the required sizes. A user-friendly self-regulating control system allows automatic operation of the plant, which means that constant monitoring by an operator is not necessary, thereby reducing operating costs.
The reducing action of the granulator, which only briefly comes into contact with the feed material, ensures that the entire plant operates with very low wear rates. The material is handled in such a way that the original grain structure of the aggregates is preserved, thereby ensuring a quality product containing minimum fines that is suitable for further processing through an asphalt production plant. The machine is offered in various models including fully mobile, skid-mounted and stationary. For further information visit: www.benninghoven.com