A special shredding plant works in continuous operation and can be serviced without long downtimes

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1 Material pollution in waste paper recycling A special shredding plant works in continuous operation and can be serviced without long downtimes (February 2013) Who removes the plastic rings from the empty writing pad or tears the plastic off the chocolate Advent calendar before disposing of it? Certainly not all of us. In this way, foreign materials and impurities find their way into the waste paper and these have to be removed during the recycling process before the material can be further processed as paper pulp. Thereafter, the separated mass, the so-called "reject material", is shredded and dehydrated, so that it can be disposed of or used internally for the generation of power. As paper machines operate 24 hours per day, there are demanding requirements for the shredding machines, too. They have not only to be suitable for continuous operation, but also for quick and easy maintenance, in order to avoid production delays. That is why the shredders have to be robust and they must be able to deal with the wet material. For this purpose, Erdwich Zerkleinerungssysteme GmbH has developed special models which can be individually adapted. In Germany, about 243 kg of paper was consumed per capita in 2010, which corresponds to a total consumption of nearly 20 million tonnes. Thereof, more than 15 tonnes was able to be recycled and reused. Thus, there is a waste paper usage of 70 per cent in the manufacturing industry an increase of 21 per cent during the past 20 years. At the same time, however, the demand for sustainability and recyclability has increased and for this reason the industry is permanently working on developing further improvements. By way of example, the recycling company operating the most rapid plant in Europe expanded its process lines by an individual shredder for foreign substances. Waste to Energy Energy carrier out of refuse The machine from Erdwich Zerkleinerungssysteme GmbH is used here in the brown 1

2 paper recycling process. For that purpose, the paper mass is dissolved in a so-called "pulper, a large container with a stirring device, before it can be further processed as wet pulp. During this process, the reject material, foreign substances and impurities such as plastic or metals, are filtered out. "At a daily throughput of 1,900 tonnes, between 100 and 150 tonnes of reject material are generated, explains Reinhard Hirschmiller, production manager at Erdwich Zerkleinerungssysteme GmbH. The separated mass is shredded in several steps, then dehydrated and used internally by the company for generation of power. In accord with the maxim "Waste to Energy", the recycled waste is used there as residual derivated fuel (RDF). "Using our mechanical engineering, the residual materials are shredded to a size of under 50 millimetres and then burnt in combined heat and power generation plants. From there, the energy is returned to the larger industrial plants - such as paper mills - in the form of process steam or on-site heating, Hirschmiller explains. "In this way, this sector supplies itself with energy." Special barriers protect against moisture and prevent wear This machine has been designed by Erdwich especially for processing the wet reject material. In the wet area, high-quality, reliable sealing systems are necessary in order to protect the bearings and gears from water ingress. "That is why we equipped the plant with sealing elements and so-called barrier walls," says Hirschmiller. The wearresistant barrier wall separates the cutting gear from the upstream seal by using stuffing boxes which provides additional protection for the main bearing seal by means of a labyrinth packing. Thus, the barrier wall also serves as protection against wear, as the machine housing does not come into contact with the bearing nor with the reject material. Furthermore, the machine bearing is well protected against the penetration of liquids and dirt by the stuffing box seal which can be replaced with little effort in a few steps. On paper machines, special attention is addressed to the reliability of continuous operation of the units, as the plant operates 24 hours per day without interruption. That is why it is important in case of maintenance work or foreign material jamming the machine that the shredder installation is mobile. This enables it to be removed from the process chain without interrupting the production process. In some cases, an additional 2

3 shredder is even installed in stand-by mode and guarantees further operation of the plant in an emergency. The circumstances influence the decision as to whether this is necessary, and the plant is then individually planned by Erdwich. "Every customer has his own specifications requiring the installation of individual components produced by particular manufacturers. That is why our engineering department has to individually convert and adapt every component to meet the specific requirements," explains Hirschmiller. Thus, in this case, the integration of the machine into the overall control system required a 100 per cent signal exchange and a correspondingly high planning effort. "To this end, our technicians provide comprehensive, customer-specific, projectrelated documentations," continues Hirschmiller. "Because finally it is important that our plants satisfy the highest demands for an extended period." 3

4 Background The company Erdwich Zerkleinerungssysteme GmbH was founded by Johann Erdwich in 1972 as a mechanical engineering and metal construction company. Presently, 35 persons are employed. The three core businesses of the company for machine and system engineering are divided into the fields of recycling and reusing reusable waste, destruction of hazardous waste of all kind and shredding of refuse for volume reduction. In the segment of recycling plants for refrigerating devices, Erdwich GmbH ranks globally under the top three companies. 4

5 Graphical material: Picture-ID: Rejectmaterial.jpg Caption: For the recycling of paper, the paper mass is dissolved in a so-called "pulper, a large container with a stirring device, before it can be further processed as wet pulp. During this process, the reject material, foreign substances and impurities such as plastic or metals, are filtered out. Picture-ID: Palm.jpg Caption: From 1,900 tonnes of waste paper, between 100 and 150 tonnes of reject material is discharged each day. It is shredded in several steps, then dehydrated and disposed of or used internally for generation of power. Picture-ID: Anlage_Förderband.jpg Caption: The machine from Erdwich has been designed especially for processing the wet reject material. In the wet area, high-quality, reliable sealing systems are necessary in order to protect the bearings and gears from water ingress. 5

6 Picture-ID: Schottwand.jpg Caption: The barrier wall separates the cutting gear from the seals. Thus, it also serves as protection against wear, as the machine housing does not come into contact with the bearing nor with the reject material. Picture-ID: Shredderwelle_Draufsicht.jpg Caption: "Using the mechanical engineering from Erdwich, the residual materials are shredded to a size of under 50 millimetres and then burnt in combined heat and power generation plants. From there, the energy is returned to the paper mills. 6

7 More information for readers/observers/sales prospects: ERDWICH Zerkleinerungssysteme GmbH Johann Erdwich, Managing Director Kolpingstr. 8, D Kaufering, Germany Tel.: , Fax: infoline@erdwich.de, Internet: More information for the editorial staff Pressebüro Beatrix Gebhardt-Seele Leonrodstraße 68, D München, Germany Tel.: , Fax: pressebuero@gebhardt-seele.de Internet: Reprint free of charge provided the source is stated, specimen copy requested 7