Recycling for assurance of materials supplies – status and potentials

Berlin Recycling and Industrial Materials Conference, Berlin/Germany (26.–27.05.2009)

Just six months after the first event of this series, TK Verlag Nietwerder held the second Berlin Recycling and Industrial Materials Conference on May 26 and 27, 2009, under the proven scientific leadership of Prof. Dr.-Ing. habil. Dr. h. c. Karl J. Thomé-Kozmiensky. A clear shift in content emphases, in favour of preparation and recycling processes, was apparent in the fact that other renowned engineers have been coopted on to the organizing committee, alongside Attorney Dr. Andrea Versteyl, of the Versteyl firm of attorneys, Berlin, among them Prof. em. Dr.-Ing. habil. Eberhard Gock, Prof. Dr.-Ing. Daniel Goldmann and Prof. Dr.-Ing. Reinhard Scholz, all from the Technical University of Clausthal-Zellerfeld, illustrating that the targeted closer cooperation with this celebrated institution had now become reality. The occasion for the conference was provided by the EU Council Directive on Waste, which came into effect on December 22, 2008, and must be implemented in Germany by December 12, 2010. More than 250 interested participants from recycling enterprises, planning consultancies, universities, administrative bodies, industrial confederations and many other institutions took up the invitation to Berlin. The conference provided a good opportunity of gathering ideas for future corporate development, conducting detailed discussions with highly competent experts, and obtaining information on the latest trends in the field of the scientific, technical and legal aspects of the preparation of waste and raw materials, and recycling.

1 Politics – Law – Industry
Moving in the tense field between the waste-management industry and waste-management policy, the speakers for the first series of topics examined political, legal, economic and general technical aspects of the recovery of useful materials from waste.

Karl J. Thomé-Kozmiensky’s opening address alone (Fig. 1) illustrated extremely clearly the significance of the council’s directive for the German waste-management industry. It does not, admittedly, mark the opening of any new age for Germany and other countries with highly developed waste-management arrangements, but it does achieve clarity of terms and definitions, and provides the same bases for all member states. Monitoring of specified recycling rates and quality parameters necessitates a high level of administrative input. There are also implications for equipment fabrication and process-engineering. There is, indeed, much that is technically feasible, but it becomes increasingly difficult to provide affordable solution routes, the greater the demands made on quality and quantity. In addition, the reprocessing of waste to achieve high-quality industrial raw materials still remains more cost-intensive than the “energy route”, which is nowadays available at rates of 60 to 80 t/t.

Undersecretary Thomas Rummler, of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU), Bonn, addressed the audience on the “Effects of the Council Directive on Waste on materials flows and resources policy”. Pressure on the earth’s ecological systems is growing, the demand for industrial raw materials is continuously expanding as a consequence of the steady increase in the world’s population, and industrial raw materials are becoming ever scarcer. A high potential contained in secondary raw materials exists, on the other hand. It is the aim of the Council Directive on Waste to conserve natural resources and optimize waste recycling, in order to achieve high qualities. Waste avoidance and recycling are highlighted as strategies, product responsibility demanded, and the circular economy promoted.
Analogous conclusions were also drawn by Burkhard Landers, president of the Bundesverband Sekundärrohstoffe und Entsorgung e. V. (Federal Association for Secondary Raw Materials and Disposal, German abbreviation: bvse), who focused in his paper on “Materials-route valorization in Germany” on the Federal Republic’s pioneering role. He called for product responsibility to take account not only of economic but also, and much more intensively, ecological aspects. Citing the examples of scrap, plastic waste, used glass and used paper, he illustrated that recycling is active resource conservation and environmental protection, and that there are no alternatives. Particularly in a resources-poor country such as Germany, materials-route recycling will increasingly become a future market.
BSR Berliner Stadtreinigungsbetriebe, Berlin’s municipal hygiene and cleaning organization, is already well on the way to achieving this, as board chairperson Vera Gäde-Butzlaff demonstrated in her paper on “Municipal resources management - added value for Berlin”. The organization, which now employs more than 5,500 persons, already reprocesses 95 % of waste, 30 % via the materials route. Transition from “trash collector to recycled-materials manager”; and from simply being a collector and transporter to becoming a plant operator, has made this possible.
Following these addresses, which assigned high priorities to the most complete and highest-quality recycling possible, Undersecretary Heinz-Ulrich Bertram, of the Lower Saxony Ministry of the Environment, Hanover asked the pertinent question of “Do we still need landfills? – The limitations of recycling”. The answer was already encapsulated in his paper’s title, signifying that recycling without landfills is not yet feasible. The landfill is an integral element in the circular economy; for both ecological and economic reasons, it is necessary as an augmentation of the overall system, but only for waste materials which can be usefully processed neither via the materials, nor by the thermal route (such as fire waste, asbestos waste, dredging and excavation waste and highway-engineering rubble containing tar and pitch).

Andrea Versteyl examined the consequential problems of the environmental subsidy (the so-called “wrecking bonus”) for purchase of a new vehicle – i.e., the storage of dismantled life-expired vehicles – and outlined “Bridging solutions for (this) recycling waste from an approval-law viewpoint”. The “Export restrictions on secondary raw materials – monitoring of waste cartage” by Olaf Kropp, of Sonderabfall-Management-Gesellschaft Rheinland Pfalz mbH, Mainz, and “Setting standards for disposal procedures via BVT codes” by Johanna Raasch, of Hamburg, papers, examined other legal questions.

The next series of topics focused on technical matters of a more general nature. Daniel Goldmann, of the Technical University of Clausthal, for example, reported on the “Opening-up of new secondary materials potentials from waste flows via the development of networked valorization structures and multi-stage upgrading processes”. As he stated, the fact that the complexity of the products which will later become waste is increasing more and more, means that technically and logistically optimized waste-to-materials conversion structures are the precondition for efficient se-condary raw-material management. The greatest possible degree of capture of waste flows and their cataloguing by quantity, points of production and times of production, plus the resource potentials they contain, provides the basis for this. Multi-stage treatment and upgrading processes permit the conversion of waste to secondary raw materials in an economically optimized manner provided various materials flows can be added or subtracted at various points in the valorization network.
Eberhard Gock, of the Technical University of Clausthal, then focused on the chronological and technical “Developments in waste processing”, examining numerous examples from research and industrial practice. He outlined, for example, solution routes for the preparation and recycling of waste from materials recovery (including slurry ponds in barytes mining, and spoil heaps in non-ferrous metal extraction), recycling of electronics scrap (filter dusts), the beverages industry (filter sludges), chemical process-engineering (phosphating solutions for corrosion protection, H2SO4 from production of TiO2 pigments) and in steel metallurgy (removal of zinc from steel scrap), all of which necessitate highly sophisticated preparation and process engineering. Mechanical reprocessing methods have predominated in the past, whereas nowadays increasingly complicated materials systems make preparation routes no longer conceivable without the use of chemical processes.
The following two overview papers, by Reinhard Scholz, of the Technical University of Clausthal, “Thermal processes for metals recycling”, and Jürgen Antrekowitsch, of the Leoben University of Mining and Technology (Austria), “Metallurgical recycling of metal-containing byproducts and scrap – a process-engineering and materials-policy challenge” examined the recycling of metals. Both speakers outlined the great potential of metals recycling in terms, on the one hand, of materials recovery and, on the other hand, of energy-savings. As was mentioned, a whole series of solution variants already exist, the majority of which still require optimization, however.

The first day of the conference (Fig. 2) closed with a platform discussion on the topic of the “Consequences of the economic crisis for the recycling market - assured valorization via municipal or private disposal organizations”, a theme which was intended to – and did – provoke lively discussion. There continues to be scarcely any conformity between private and municipal disposal organizations, despite the fact that both sides argue in favour of healthy co-existence.

The second day of the conference was divided into three sections, held in parallel:
• Preparation equipment
• Plastics waste – Urban mining – Mineral waste
• Life-expired vehicles – Electrical and electronics scrap – Iron and non-ferrous metals. In line with AT International's brief, we report here on the papers from the first category in rather greater detail.

2 Preparation equipment
August van der Beek, of Metso Lindemann GmbH, Düsseldorf, reported on “Perspectives in shredder technology”. His main focus was on the central element of these metal-recovery systems, the shredder, which makes up the first comminution stage in the recycling of life-expired vehicles. The “Power Zerdirator”, a hammer mill equipped for wear reasons with freely swinging hammers and screens, as well as a dedusting system, was highlighted, for example. The machine is available in various sizes (rotor-cross diameter 1.75 m to 3.00 m), and is capable of producing 40 000 to 500 000 t/a of finished product. Specific production costs are around 15 t/t for the smaller systems, reducing to approximately half of this for larger installations. The integration of a classifier permits separation into a light and a heavy shredder fraction. Further metal contents are recovered from both of these fractions. Dedusting can be simplified via the injection of water (fixing of dust, and reduction of the danger of explosion, thanks to expulsion of O2). The company has the world’s largest comminution pilot facility and can supply all-in shredder installations if required.
Walter F.  Weber, of MHG Maschinenfabrik Hombak GmbH, Zweibrücken, examined the entire spectrum of comminution machinery used in the recycling sector (cutting, hammer and impact mills, and also granulators). He focused particular attention on the thorny problem of wear, which is countered via the development of corresponding wear elements. The influencing parameters of the individual machines were discussed, and various special processes examined, including, for example, the use of cryogenics for digestion and breakdown of composite materials (separation of metal and rubber in the case of tyres, for example).

A relatively simple but operationally reliable and affordable procedure was presented by Michael Bräumer, of mbb – Ingenieurbüro für Aufbereitungstechnik, Bernsdorf, in his address on the “Upgrading of minerals from waste via wet processing on the vertical jig”. Organics-containing waste is removed in order to maintain < 3 % TOC (disposal criterion) in a vibrating sorting tube similar to a dredger hose and featuring a wear layer of 10 to 12 mm. Applications include the cleaning of road sweepings, drain and sewer cleaning waste and screened sand from cleaning of mixed building waste.

The paper “Screening technology for removal of fines” by Uwe Bruder, of Derrick Corporation, Hirschau, focused on the optimization of fine screening. Examination of theoretical considerations was followed by illustration of practical implementation of the knowledge thus obtained. It is, above all, design modifications to the dry and wet screens, including the screen decks, application of water to the screens, and variation of the operating parameters, which permit high-selectivity screening in the fines range (around < 500 µm). High frequencies at low amplitudes, combined with large open screen surfaces areas, guarantee high processing rates and product qualities. Such screens are increasingly coming into use, particularly in Europe, in recycling plants for various materials systems, in addition to their traditional applications (ore and minerals preparation and the sand industry).

In his paper on “New potentials in density-based sorting”, Hermann Wotruba, of the RWTH Aachen, outlined the increasing importance of dry processes resulting from the increasingly diminished availability and increasingly high costs of water. He also mentioned the limitations of the known processes, however: low specific throughputs, tightly classified feed, and the absence of automatic extraction. Against this background, he disclosed, the RWTH Aachen is busy developing a new dry-functioning jig (the allair jig). Air pulses are transmitted here, by means of the combination of the correct air flow and pressure, via vibration through a flowing bed. This stratifies the material, permitting separation. Extraction control is accomplished by means of radiometric measurements of density. The achievable selectivity is comparable to that of wet jigs. Applications include the removal of bitumen or gypsum from rubble, for example. The limitations of such systems can be found in the < 2 mm particle-size range, for which a further machine has been developed, the dry-functioning fluidized-bed fines classifier (Akaflow), which is suitable for separation of multiple products and has been successfully used in the density sorting of stainless steel slag, for instance. Potential applications in the field of recycling still remain unknown up to now, however. Operators with corresponding tasks requiring solution are therefore being sought.

Another dry-functioning separation process was explained by Markus Riggemann, of Trenn- und Sortiertechnik GmbH, Weißenhorn: “Dry separating tables for waste processing”. Riggemann drew attention to numerous examples to demonstrate that good separation results can also be achieved in the field of recycling using tables sloping in both one and two dimensions, after appropriate modification to match the particular task (e.g. processing of household refuse, electric cables, electronics scrap and shredder lights). Narrow fractions, he stated, are necessary to permit optimum separation, and prescreening is therefore recommendable. The machine is notable for its simple use and handling, robustness and durability.
In his paper on “Observations on the sorting of particle systems by particle geometry”, Dipl.-Ing. Martin Steuer, of the Technical University and Mining Academy of Freiberg, stated that sorting on the basis of particle morphology can be extremely successful in the case of mixtures in which the geometry can be correlated to differing productspecific characteristics. A high-throughput and high-performance particle-geometry sorting principle, serial classification, has been developed to exploit this principle. This classification method involves sorting by means of chronologically and spatially separate classification on the basis of at least two characteristic particle dimensions. Any mechanical screen is potentially suitable for the application of this principle. The new particle-geometry classification process has been patented and is currently undergoing industrial-scale testing in the form of double serial classification.

Another sorting concept was the subject of the address by Ulrich Kohaupt, of Steinert Elektromagnetbau GmbH, Cologne: “Aspects in the selection and use of eddy-current separators”. Under this principle, which is suitable for the separation of non-ferrous metals and permits classification down to a particle size of 1 mm, economic efficiency is a question of the selection of the correct technology. The eccentric pole system developed within the company has significant advantages over other eddy-current separators, including the adjustability of the pulse, greater spacing between the two discharge parabolas, and therefore more space for the vertex plate. The eddy-current separator does, it is true, require higher levels of investment, but these are balanced out by greater availability and superior separating performance.

A further example of an application in waste processing was analyzed by Rainer Köhnlechner, of hamos GmbH, of Penzberg: “The use of electrostatic separation technologies for industrial byproducts – electrical scrap, cable waste and mixtures of plastics”. Electrostatic separators have, admittedly, been in use for no less than one hundred years, but only for around twenty years in the waste-management sector, for separation of metals from plastics, for instance. This sorting process is particularly in demand in cases in which valuable raw materials, such as metals, can still be recovered from product mixtures which cannot be further separated using conventional methods. The broad spectrum of potential applications was outlined using a large number of examples, including the processing of cable waste, separation of HDPE and PP, separation of aluminium and plastics in composite waste, and the recycling of life-expired window systems.
A comprehensive status report on “Sensor-assisted processing systems” was provided by Thomas Preetz, of the RWTH Aachen. Sensor technology, which was initially used for quality-control purposes in the foodstuffs sector, is now a fixed feature in the recycling industry, with steadily expanding applications. It forms the technological basis for quality-assured secondary materials production. Summarizing his observations, Preetz noted that the technical possibilities offered by sensor systems have still not by any means been exhausted. Quality assurance is a decisive factor on the road to successful secondary raw materials, and sensors can be used here to control preparation processes and provide the key to success.

Citing the example of a production process for substitute fuels, Jan Rosenkranz, of the Technical University of Berlin, furnished proof that “Model-assisted simulation of mechanical preparation processes for treatment of household waste” permits detailed computation of complex preparation pro-cesses. The generation of a mathematical model for description of physical material conversion in the individual interlinked basic process-engineering operations, and the use of this model in a closed simulation computation for the pro-cess as a whole, makes it possible to study the behaviour of aggregates in a treatment plant for various feed materials, and also featuring fluctuations in composition, as early as the design phase. The model implementation also includes po-tentials for performance of technical system tests and trials.

3 Plastics waste
This series of papers focused both on questions of waste management, market data on plastics recycling in general (Holger Alwast, of Prognos AG, Berlin) on PVC, in particular (Werner Preusker, of AG PVC und Umwelt e.V., Bonn) and on technical processing matters (Peter Wiedemann, WIPAG Süd GmbH & Co. KG, Neuburg: “Comminution and separation of plastics”; Jörg Woidasky, Fraunhofer ICT, Schwanewede: “Technical perspectives in plastics recycling”). All these addresses emphasized the great potential of plastics recycling and the fact that this must be exploited not only in Germany, but throughout Europe.

4 Mineral waste
The tonnage waste yielded in the mining and construction industries continues to offer a broad field for the research, development and industrial application of recycling pro-cesses, as was outlined in five papers presented at the con-ference. The spectrum examined ranged from recycled building materials (Undersecretary Otto Bischlager, of the Bavarian State Ministry of the Environment and Public Health, Munich: “Valorization of recycled building materials in highway engineering in Bavaria”), via “Valorization of power-generating plant byproducts and gypsum-containing waste from decommissioning projects” (Michael Zingk, GFR mbH, Hanover), up to and including “Valorization of dry extracted ash and slags from waste incineration” (Norbert Eickhoff, Martin GmbH für Umwelt- und Energietechnik, Munich). The potentials for recycling and utilization of such secondary raw materials are considerable, but continue to be hindered by reservations on the part of possible users.

5 Life-expired vehicles
The life-expired vehicle recycling sector, which is currently enjoying a boom, illustrates extremely impressively how legislation (environmental regulations) and the increasing costs of primary raw materials have resulted in a one-time waste flow developing ever more into a source of secondary raw materials. New treatment technologies and sales channels for secondary materials generated from the complex mixture of waste that constitutes life-expired vehicles have expanded the valorization chain, as Daniel Goldmann, of the Technical University of Clausthal, noted in his observations on the “Status of life-expired vehicle recycling - developments during the past twenty years and perspectives for the future”. Central topics in processing of life-expired vehicles are the shredder machines and their materials output flows which, against the background of new legislation, are now the focus of numerous studies, design and technical modifications, and discussions. These problems were the subject, for instance, of the papers presented by Detlef Alsleben, of DEUMU – Deutsche Erz- und Metallunion, Peine (“Supply of scrap to the steel industry – the shredder as the central element in secondary materials preparation”), Ioannnis Karanatsios, SICON GmbH, Hilchenbach (“Processes for preparation of shredder lights”) and Thomas Bürgler, voest alpine Stahl GmbH, Linz, Austria (“Materials flows from shredder byproduct processing for [raw] mate-rials-route recycling-experience gained in industrial operation”).

6 Ferrous and non-ferrous metals
The subject of “Modern copper recycling” was examined by Christian Kawohl, of Aurubis AG, Lünen, and will very likely be of great interest in the mid- to long-term, despite the current collapse of prices on the metals markets. The same is also true of zinc-bearing waste, which mainly originates from the recycling of zinc-plated steel, in the form either of EAF (Electric Arc Furnace) dust and as sludge from zinc-plating shops, and also as filter dust from foundries. Reimund Westphal, of Recylex GmbH, Goslar, illustrated the technical methods which have been developed for this purpose, and the economic and ecological targets which can be achieved using these processes. Recycling of life-expired products, he commented, is a vital necessity for the conservation of resources and protection of the environment, particularly in the energy-intensive processes for production of metals from ever poorer and ever more depleted primary raw materials. The same is equally true of lead, which this speaker also included in his observations (“Recycling of lead- and zinc-bearing waste”).
7 Concluding remarks
The conference illustrated the recycling and processing of waste from the most diverse range of materials systems under the conditions imposed by recent legal provisions and, in particular, the European Council Directive n Waste. The various overview papers examined important technological aspects of recycling, with particular attention to processing, and also metallurgy. A large number of applications were cited to demonstrate that waste processing nowadays signifies recovery of the useful materials contained in the initial product with as little loss as possible. The classical reprocessing methods are, in addition, now no longer adequate, and processes are thus becoming ever more complex, while sensor technology is becoming more and more firmly established for the improvement of separation efficiency. The papers included not only practice-based addresses, but also scientific work, the practical implementation of which will result in further technological advances.

The participants at this conference also had adequate opportunity of discussing these and other topics with their specialist colleagues (Fig. 3). This year’s Berlin Recycling and Industrial Materials Conference was thus again a platform for all persons interested in these fields, and provided these persons simultaneously with an opportunity of making new and consolidating existing contacts.

The majority of the papers included in the conference agenda have been published in “Recycling und Industrial raw materials” Volume 2, TK Verlag Karl Thomé-Kozmiensky, Neuruppin 2009, ISBN 978 –3-935317-40-5.      Hf


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