ENVIRONMENTAL FOOTPRINTING OF METALLURGICAL COPPER PROCESSING TECHNOLOGY

Transcription

1 To be Copper 2013 Chile ENVIRONMENTAL FOOTPRINTING OF METALLURGICAL COPPER PROCESSING TECHNOLOGY -Linking GaBi to HSC Sim- M.A. Reuter, I. Kojo, A. Roine and M. Jåfs Outotec Oyj Riihitontuntie 7 Espoo, Finland markus.reuter@outotec.com J. Gediga and H. Florin PE-International Hauptstraße Leinfelden-Echterdingen, Germany ABSTRACT This paper will discuss the use of HSC Sim ( and GaBi ( for foot-printing process technology and complete plant and larger system solutions (e.g. recycling chains). In a recent development together with PE- International, HSC Sim s simulation functionality has been expanded to create files that can be exported in a format that can be directly loaded into GaBi to create a GaBi-model from a complete HSC Sim flowsheet and subsequently produce an environmental assessment locally positioned wherever the plant is situated. This is very useful for the evaluation of existing industrial plants represented by suitable HSC Sim flowsheets, as well as the evaluation of various scenarios to estimate the impact of newly designed solutions based on the rigor of metallurgical flowsheeting (mass and energy balances) and associated process models. It goes without saying that this connection enables the access to highly detailed process information through HSC Sim and thence providing a rigorous basis on which to perform environmental impact assessment and identify the best process options for each site based on the local conditions and energy footprints. In addition to this LCA analysis, HSC Sim has also been expanded to include exergy, which is rather useful to also understand the entropy flows in systems permitting evaluating systems on a more fundamental basis.

2 INTRODUCTION Metals are an essential and critical component of today s society: a moment s reflection on their ubiquitous presence in virtually all energy and material production processes, products, infrastructure, confirms this. Metals play a key role in Enabling Sustainability through societies various high-tech applications. However, the resources of our planet are limited, as is the strain to which we can subject it in terms of emissions, pollution, and disposal of waste. For these reasons, finding ways to lower the environmental footprint of our collective existence and therefore lowering greenhouse gas emissions and help mitigate climate change is a vital priority [1-2]. The maximization of resource efficiency [3-4] is the underlying theme of this contribution. It will be shown what depth and detail that is required to systemically fully understand resource efficiency in the context of material use and copper metal production. Design for Resource Efficiency is elaborated on with on the basis of physics rather than simplistic material flow analysis approaches which provide no basis to improve resource efficiency as is the usual methodology in environmental impact assessment. In support of this, the detailed data that are required, the technological understanding and design that impact on resource efficiency is reflected by Figure 1. The highlighted aspects in Figure 1 are among others implicitly and explicitly discussed include multi-physics modeling within a feasible techno-economic framework. Figure 1 Resource Efficiency and how it relates to metal production in its systemic complexity.

3 The metal and material interactions in the system can be rather complex if one considers not only primary but also secondary resource as reflected in by the complex designed copper minerals in end-of-life products in Figure 2. Chalcopyrite CuFeS 2 and >15 minors e.g. Au, As, Ag, Se etc. Material combinations and Designed Consumer Minerals Material connections Designer Copper Minerals >40 elements complexly linked Figure 2 Improving resource efficiency relies on detailed knowledge on the interaction of all elements in primary as well as secondary recycled resources as depicted by Figure 1 copper metallurgy is a key metal for enabling recycling of e-waste [4]. Joined Materials Company Location Technology Production from secondary Cu (tpa) Dowa Mining Kosaka, Japan Ausmelt TSL 25,000 Korea Zinc Onsan, ROK Ausmelt TSL Unknown Global Resources & Materials Danyang, ROK Ausmelt TSL 25,000 Figure 3 Some Outotec technology for the smelting of secondary resources (e.g. e-waste, copper containing materials and recyclates) applied in closing the loop in Figure 1.

4 It would be self evident that the environmental impact studies for primary and secondary/recycling metals production must consider this non-linear detail to ensure that all aspects of the impact are well understood. If for example recycling is considered, the detailed metallurgical processes occurring in furnaces such as shown in Figure 3, that distribute the various compounds and elements in Figure 2 to various phases, should be included in the evaluation. This would provide a complete and more detailed picture of the complete material cycle and therefore provides insight into how resource efficiency can be improved. It also ensures that data collected for these systems are in a format that can be used and applied in rigorous process simulation as required by for example HSC Sim type of process simulation including all minerals, phases etc. Rigorous process simulation as shown Figure 4 [5] is very helpful to close the material balance for all the included process and hence be a valuable tool to minimize the losses as reflected in Figure 1. This figure shows the processing of end-of-life products, inclusive of dismantling as well as final metal production (inclusive of refining). Figure 4 A process flowsheet for End-of-Life products using HSC Sim.

5 EXPLORING THE FUNDAMENTAL PROCESS BENCHMARK It is clearly evident from the above that in order to fully understand the environmental impact of metallurgical processes requires deep knowledge of the various aspects of the whole material chain. A detailed environmental impact evaluation of Best Available Technique (BAT) without considering all the mentioned detail for example in a typical copper flow sheet as shown by Figure 6 would not help to innovatively improve the fundamental benchmark of the industry as depicted by Figure 5. Cu Process/Plant/System - KPIs (Minimize losses hence maximize resource efficiency) System Integrated Copper Processes Driving Cu-processes ever closer to their systemic, technological and hence physics based limits, while decreasing product variability. The ultimate benchmark of Copper industry sector Fundamental Cu Process and System Benchmark Techno-economic based New Cu Process Benchmark Technology and Systemic Innovation (Digitalization) Present Time (Years) Figure 5 Improving Resource Efficiency by systemically approaching the fundamental techno-economic limits of metal production systems (yellow dots) i.e. the ultimate attractor of a resource efficient copper industry (BAT: Best Available Technique). Figure 5 depicts the ambition of the copper industry to get closer to the technoeconomically feasible resource efficiency, by quantifying all losses and therefore better understanding which aspects impact most the migration to the ultimate operating point for the copper industry. Also possible innovation may lower the ultimate achievable operating point that will increase resource efficiency even further. In this paper we will briefly discuss how rigorous process tool can be used for example to evaluate typical copper plants as shown in Figure 6 (for example). To assist in this also environmental impact the GaBi software will be used that has been linked to HSC Sim as shown in Figure 7.

6 Figure 6 A primary copper flow sheet for the smelting of copper concentrate depicting various Outotec technologies inclusive of Flash Converting and Kaldo. LCA software as shown on the right in Figure 7 generally relies on average process data for the various metals to assess their impact when used in product design and applications. As there are variations in any flowsheet as well their application of BAT in addition to processes being situated at different locations globally, impacts due to changing energy mixes, resource impacts, and transport, and etc., environmental impacts for a specific plant can vary significantly around the average. It can therefore be very useful to evaluate the impact of specific processes at specific locations to assess their real impact as well as reveal true potential for process improvement. This rigorous link provides some obvious and very useful benefits, which include: Maximizing the strengths of each software platform and their respective databases (thermochemical and environmental respectively) to evaluate systems. At the same time this rigorous link will also reveal weaknesses which would then provide the true points which have to be improved to ensure that resource efficiency can be realized to its techno-economic limits. All streams are mapped in detail including all compositional data not only as elements but also as compounds as a function of a unique concentrate feed suite (e.g. LCA databases detail only a few slag types, while in fact each process has its unique slag) or recyclate and residue suite for secondary processing. Flue dusts and other fugitive emissions can be quantified and/or characterized at least to understand their full impact.

7 Rigorous closed mass and energy balances for each element are given. In many cases the average LCA databases do not provide consistency in this regard. HSC Sim can also provide exergy data. Therefore combining exergy and LCA type information can help much to further drive copper production to its technoeconomic limits. Harmonizing the LCA and the metallurgical process simulation community has enormous advantages. The simulation component provides the total freedom to create whichever process and impact it, obviously if appropriate environmental data is present in the GaBi database that can be mapped to the flows in the simulator. Figure 7 The linking of rigorous simulation and design tool HSC Sim ( and PE-International s ( GaBi software. The example links concentrator, smelting and refining inclusive of sulfur capture to GaBi to provide the shown environmental impact bottom right. Due to the unique situation that exists at each industrial facility, we do not present specific data in this paper as it would not be representative. Simulating BAT with HSC Sim and calculating an impact with GaBi must be done separately for different industrial facilities, because average values may lead to incorrect conclusions and in the end do not show what has to be truly improved at each facility. This is a rigorous goal to strive for i.e. to get the lowest impact for each facility with its unique technology and feed suite, which will obviously lower the footprint of the complete industry.

8 RESOURCE EFFICIENCY QUANTIFIED BY RIGOROUS SIMULATION Figure 8 forms the basis of all the data and simulations that are used in this discussion. This figure shows a typical flash smelting furnace and Peirce-Smith converters as well as sulfuric acid and refining plants. Also some mass flow data in kg/h are shown as well as some data for the FSF slag stream. Figure 8 A HSC Sim 7.1 simulator version of Figure 6 with some detail of the slag stream shown on the right hand side window. This model is the basis for the discussion example in this paper, noting that converting is done in Peirce-Smiths. The software link depicted by Figure 7 makes it possible to create GaBi processes from the HSC Sim process simulation models for complete plants or reactors as shown in Figure 8. These processes can now be used to create any GaBi process. The next figures depict some of the software steps using the LCA functionality within HSC Sim including among others the following: After creating a simulation model as shown in Figure 8 all streams can be collected depicted by Figure 9. Following the various tasks as shown on the bottom tab (Mapping, Normalize, Export, Get Indicators, Save, Close), manual mapping is performed that links all the HSC Sim flows (which can have arbitrary

9 names) to equivalents in the GaBi database. The structure and data names tags are duplicated in HSC Sim as shown. The mapping also indicates if streams flow to the environment or the techno-sphere for example. This selection obviously also has an effect on the final environmental impact thus careful selection is required by knowledgeable individuals. The product is selected as shown Figure 9, which is the flow around which all other streams are normalized in this case blister copper is the pivot. Subsequently data is normalized by using the appropriate action in HSC s LCA functionality tool after various manual input are entered that do not appear in the simulation such as blowers, launder gas burners etc. This is depicted by Figure 10. Figure 10 also shows that all similar streams from the GaBi point of view are collated i.e. all streams with the same GaBi name allocation are added. Subsequently these data can be exported to GaBi to produce a process as also reflected by Figure 10. This process is now saved in the GaBi databases (appears as a HSC sub-directory in GaBi collecting all HSC processes) and can be used for example as a BAT copper production process, with a fully consistent mass and energy balance. This is interesting if for example Original Equipment Manufacturers (OEMs) are considering selecting the environmentally cleanest possible materials in their products in the environmental evaluations.

10 Figure 9 The LCA-Functionality in HSC Sim showing how variables in the simulator and their names are collected and subsequently mapped to the GaBi database variables with a mapping tool that contains the GaBi variable database listing (right window)

11 Figure 10 After the mapping as shown in Figure 9, data is normalized to GaBi variables (i.e. all mappings with same GaBi variable name are collected) and subsequently can be exported to be directly imported as a process as shown by the right hand figure from GaBi QUANTIFYING RESOURCE EFFICIENCY & SUSTAINABILITY From Figure 10 it would be clear that a complete flowsheet is summarized (crunched) into one black-box GaBi-process and can now be used in GaBi. As mentioned all flows are balanced, which is not necessary the case in the usual environmental databases. If required an LCA can be done for a reactor, or a complete production site or a complete system as shown by Figure 2 and Figure 4, hence the approach is totally scalable and hence extremely useful for process benchmarking. Figure 11 shows three processes simulated with HSC and exported to GaBi and subsequently used within GaBi to produce a GaBi plan that links mined material to final refined cathode. Once this GaBi-plan has been created as depicted by Figure 11 various other analyses can be done such as showing the Sankey energy flows for the selected inputs (which vary in this case from a Finnish energy mix, to GaBi specific data for the production of the materials as well as German Oxygen production data, EU fuel production impact data the user can select from various in the GaBi database).

12 Figure 11 The energy Sankey diagram for the given processes in copper production as simulated with HSC Sim and presented by GaBi, starting with flotation and ending with refined copper product via flash smelting and Peirce-Smith converting. Figure 12 A GaBi impact assessment based on the HSC Sim simulation of the flowsheet in Figure 8 showing the Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP) and the Ozone Depletion Potential (ODP).

13 Each process that has been extracted from HSC Sim is a consistent black-box of that process only revealing the major in- and outflows. This is extremely powerful to disseminate consistent data for all copper making processes which support the usually more average data found in the environmental databases. The concise results documented above make clear that each selection of inputs of materials will provide a new answer, hence making more detailed results than the generalized Figure 12 (from which quantitative results have been removed) rather impossible to present, lest a biased picture is presented. Nevertheless, Figure 11 shows that electricity generation has the major impact in the first 3 categories shown and oxygen production in the fourth for the given simulated BAT technology and plants and the indicated input suite. The rigor of the HSC Sim process simulation makes it also possible to evaluate the exergy flows [5] of the system as shown for example by Figure 13, from which it is clear where the biggest losses take place. These obviously will and are being addressed for the copper industry to approach the attractor (yellow dots) in Figure 5. Figure 13 The exergy flow diagram for a typical copper smelting plant. CONCLUSIONS This paper briefly shows that the combination of rigorous process simulation (that produces closed mass and energy balances as well as exergy flows) and environmental impact software can provide a very useful basis to evaluate complex material flow and metal production plants and systems.

14 This combination also provides an unbiased basis for benchmarking technologies and plants while at the same time also revealing strengths and weaknesses not only in technology but also in assessment platforms and tools. This provides a rigorous basis to drive innovation and Quantify Sustainability; it reveals what can be done to improve rather than just showing how bad industry is, it enables sustainability by suggesting also solutions. In addition this HSC Sim and GaBi link renders transparent environmental computations and impact assessments and opens the dialogue between the different actors which includes process metallurgical simulation, the usual basis in any discussion in the process metallurgical world. This link will also help to bring thermodynamics and process physics more rigorously into policy discussions around environmental legislation. This was also recently mentioned on the European Commission s Resource Efficiency platform website [6]. REFERENCES 1. B.D. Santer et al., A search for human influences on the thermal structure of the atmosphere, Nature, Vol. 382, 4 th July, 1996, IPCC, Climate Change 2007: Synthesis Report Synthesis Report, An Assessment of the Intergovernmental Panel on Climate Change, This underlying report, adopted section by section at IPCC Plenary XXVII (Valencia, Spain, November 2007), represents the formally agreed statement of the IPCC concerning key findings and uncertainties contained in the Working Group contributions to the 4 th Assessment Report (2007). 3. UNEP, Metal Recycling: Opportunities, Limits, Infrastructure, A Report of the Working Group on the Global Metal Flows to the International Resource Panel. Reuter, M. A.; Hudson, C.; van Schaik, A.; Heiskanen, K.; Meskers, C.; Hagelüken, C., 2013, 316p EUROPEAN COMMISSION, Brussels, , SEC(2011) 1067 final, Roadmap to a Resource Efficient Europe, {COM(2011) 571 final} {SEC(2011) 1068 final}, M.A. Reuter, Limits of Design for Recycling and Sustainability : A Review, Waste and Biomass Valorisation, Vol. 2, 2011, European Commission