Overath SLM and Overath EPP

In the category ‘Think big! Complex energy efficiency projects’, the award goes to the tools manufacturer Overath SLM of Lohmar in North Rhine-Westphalia, and its sister company Overath EPP of Oebisfelde in Saxony-Anhalt, manufacturers of moulded foam products. These two have been able to make a leap in innovation by manufactur-ing tools using a 3D printing process. The energy savings achieved amount to 86 per cent during manufacturing of the tools and 79 per cent during their subsequent use.

Overath SLM develops and manufactures tools for series production of moulded parts in the particle foam industry. The activities of its sister company, Overath EPP GmbH, include producing assembly parts made of expanded polypropylene for the automotive industry, and using these tools for processing.

The core idea of this project consists of using an innovative 3D printing technique based on ‘selective laser melting’ (SLM). Overath SLM is able to save on material and reduce the weight of the tools using this process. Moreover, stainless steel is used instead of aluminium, which is energy-intensive to produce. This means high savings of energy and CO2 can already be achieved in the upstream chain.

In addition to these savings on energy and materials during manufacturing of the tools, considerable and specific advantages over conventional technologies also arise when they are used in the production of particle foams. The 3D printing technique results in a considerable reduction in energy use – up to 80 per cent – and a reduction of cooling water requirements.

The newly decoupled industrial heat is generated in the so-called contact plant during the conversion of sulphur dioxide, which is obtained during copper refining, into sulphuric acid. The exothermic chemical reaction releases the CO2-free heat. However, in order to be able to use it for external heat supply, it was necessary to raise the temperature level of the process from the current 65 °C to 117 °C. The process is now being operated at a temperature of 117 °C. This is the temperature at which the heat is released. This necessitated process engineering changes as well as new materials and plant components.

Aurubis and enercity conduct most of the industrial heat generated via a specially constructed 3.7 km heat transport pipeline from the plant site to eastern HafenCity. Aurubis also uses a quarter of the industrial heat in its own processes, such as heating the electrolyte during copper electrolysis. This reduces the company's natural gas requirements by around 50 gigawatt hours per year, which corresponds to an annual CO2 reduction of over 14,000 tonnes. The heat extraction measures were implemented in spring 2018. The first use of heat in HafenCity took place in late autumn 2018.

Energy efficiency measures

  • Adaptation of the sulphuric acid process to increase the temperature level
  • decoupling of industrial heat by technical conversion of the contact system
  • Erection of an internal heat transport pipeline
  • Transmission of industrial heat to supply eastern HafenCity with district heating
  • Use of industrial heat for in-house processes
  • Savings of 12 million m3 of cooling water per year

jury assessment

The jury selects Aurubis AG as the winner of the Energy Efficiency Award 2018 in the Energy Transition 2.0 category. The waste heat is now also used outside the plant in addition to being used internally. The external use of the waste heat by enercity Contracting NordGmbH makes a significant contribution to the climate protection goals of the City of Hamburg. With the help of industrial heat, it is even possible to fall short of the ambitious emission targets for supplying heat to the new HafenCity Ost development area. By using part of the heat internally within the plant, Aurubis can also cover almost half of its heat requirements for copper electrolysis and electrolyte treatment. The project has already been awarded as a lighthouse project of dena for waste heat utilisation and is one of the first major projects to be supported by the KfW promotional programme "Waste Heat".

company profile

Aurubis AG is an international supplier of non-ferrous metals and one of the largest copper recyclers in the world. The company processes complex metal concentrates, scrap metals and metal-containing recycling materials into metals of the highest quality. Aurubis produces more than 1 million tonnes annually.

copper cathodes and uses them to manufacture various copper products such as continuous cast wire rod, shapes or special wires and copper alloys.

Aurubis employs around 6,500 people and has production sites in Europe and the USA.