Decision making to support sustainability in the copper industry: technology selection

Transcription

1 Decision making to support sustainability in the copper industry: technology selection D. P. Giurco, M. Stewart and J. G. Petrie Department of Chemical Engineering University of Sydney Sydney, New South Wales 2006 Australia Sustainability: the integration of social, environmental and economic perspectives, is an issue of paramount importance to the future of the minerals and metals industries. This paper explores the local and global environmental impacts arising from the mining and primary production of refined copper for the major regions of the world. The macro-distribution of copper mining, refining and consumption are presented together with a technology-specific breakdown of primary production method, namely: flash smelting; reverberatory and electric smelting; and heap leach, solvent extraction, electrowinning (SX/EW). The environmental performance of each process is modelled using Life Cycle Assessment (LCA). The issue of local conditions and regional bias is explored in a more detailed case study comparing the performance of technologies operating in Chile and Australia. An indication of how technology-based decisions can be made to support sustainability is provided through a scenario analysis. This scenario explores the change in environmental burdens arising from replacing ageing reverberatory smelters with flash smelters or SX/EW. INTRODUCTION Presently, the minerals processing industry is seeking ways to better integrate the principles of sustainability into its operations and corporate strategies. It recognises that due consideration must be given to environmental, social and economic issues together, in order to make meaningful progress towards sustainable development [1]. This paper contributes to the minerals and sustainability question, with a focus on the environmental component of sustainable development within the context of the copper industry. Minerals and metals are global commodities whose mining and processing give rise to a diversity of environmental impacts. These environmental impacts are both local and global. A significant challenge facing the minerals industry is to better understand these local and global impacts in the context of technologies used for minerals processing. This will enable the most appropriate technologies to be chosen in given situations. Life Cycle Assessment (LCA) is introduced here as a tool to obtain an environmental profile of mineral processing activities in the copper industry. This will establish an environmental performance baseline for the status quo of the industry against which new technologies can be compared. In this paper, results are presented which enable the exploration of trade-offs in environmental effects between major technologies currently in place. By providing information to decision makers about the local and global environmental burdens associated with particular technologies, decision makers are better placed to guide the industry on a path towards sustainable development. APPROACH To begin, it is necessary to map, in each region of the world, the distribution of copper flows through the material economy, in order to provide a context for the associated environmental burdens of copper processing which will later be detailed. This regional analysis serves to highlight the disparity between production occurring mainly in the developing world and consumption occurring mainly in the developed world. In so doing, wider questions of equity and distribution begin to be raised. The arguments around social considerations will not be developed in greater depth in this paper. Notwithstanding, the results from this study can be used as a basis for discussion around social issues arising from the environmental impacts presented. The decision context for this paper is the copper industry. However, the methodology proposed is transferable to other primary metal industries. After aluminium, copper is the most widely used non-ferrous

2 metal with an annual production in excess of 12,000,000 tonnes [2]. It finds wide usage in electrical and electronic goods and is an important world commodity. The statement by Hilson [3] that; "the development of cleaner minerals technologies has contributed substantially to the prevention of pollution and improved environmental performance", has remained largely untested on a global scale. This paper will outline a baseline environmental performance for the status quo of the industry in The long term aim of this research is to guide a strategic embracing of new technologies in appropriate locations, through a better understanding of each technology's environmental performance. The reason for a focus on technology is that for a particular location and grade of an ore, the technology selected for processing the ore to refined metal is pivotal in defining the overall environmental impact. This is explored in a detailed case study comparing the current performance of Chilean and Australian technologies. It includes differences between ore grades and electricity generation methods between the two countries. Having established a baseline environmental performance for the industry, one can investigate how the environmental performance of geographic regions would change if different technologies were to be introduced. It is important here to consider all technically feasible technologies as well as those currently operating. In this paper, a scenario is explored where ageing reverberatory smelters are replaced worldwide with either of two newer options: flash smelting or heap leach SX/EW. This serves as a key example for demonstrating the methodology of how environmental sustainability can be supported through informed decision making around technology selection. MATERIAL ECONOMY OF COPPER Figure 1 provides an indication of macro-flows of copper globally, showing the distribution of extraction, primary production (from virgin ore) and consumption worldwide. The countries within each region depicted in Figures 1, 2, and 7 are listed in Table 1. Secondary production (that which uses recycled material as a feed) was not monitored in this study. The majority of copper mining occurs in Latin America, whose production is dominated by Chile. In North America, Africa and Central Asia, primary production of copper is approximately equal to the amount of copper mined in these regions. In the resource intensive economies of Latin America and Oceania, copper concentrate is exported and the local primary production is reduced. This exported copper concentrate finds its way to the highly industrialised region of Europe and to Japan. These intercontinental flows reinforce the need to study the industry at a global level. Europe, Japan (and also China) import copper concentrate for processing to refined copper in order to supply their significant local demand. The remaining shortfall in demand in the more industrialised regions Figure 1: Location of copper mining, primary production and consumption for regions of the world. (compiled with data from [2]).

3 of North America, Europe and East Asia comes predominantly from the less industrialised region of Latin America. The difference in geographical distribution of copper ore extraction and final copper consumption raises important issues. With the developing countries of the southern hemisphere supplying the majority of material for consumption in the largely industrialised northern hemisphere, the issue of equity of distribution is introduced. In the context of sustainability, as well as considering less harmful methods for primary production which is the focus of this paper dematerialization and recycling within industrialised economies must also be included in the wider discussion. Table 1: Description of countries falling within regional classifications depicted in this paper Region Countries North America Canada, United States of America Latin America Mexico and Central America, South America Europe Western Europe, Bulgaria, Cyprus, Macedonia, Poland, Romania, Serbia, Slovakia Central Asia Russia, India, Armenia, Georgia, Iran, Kazakhstan, Oman, S. Arabia, Turkey, Uzbekistan East Asia China, Mongolia, Nepal, Japan, South East Asian and Pacific Rim countries Africa All of Africa Oceania Australia, Papua New Guinea, New Zealand TECHNOLOGIES Three technology classes were modelled in this investigation, which together account for over 90% of copper processing undertaken around the world in [4]. These are: 1. Flash smelting & similar technologies 2. Reverberatory Smelting & Electric Smelting 3. Hydrometallurgical Acid heap leach, Solvent Extraction & Electrowinning (SX/EW) Flash Smelting Outokumpu flash smelting is the dominant technology utilised in the copper industry today. Approximately half of all smelters currently operating use the technology, which is still being installed in new operations [5, 6]. Outokumpu technology is the basis for environmental performance modelling using LCA in the flash smelting class. However, at the level of model detail accommodated in this study, other high intensity oxygen enriched smelting technologies such as Inco flash smelting, Noranda, El Teniente, Mitsubishi and IsaSmelt are considered similar. Reverberatory & Electric Smelting Reverberatory smelting was once the mainstay of smelting operations, but the last new reverberatory furnace was commissioned in 1976 [7]. It has largely been replaced by flash smelting technology which is less costly to operate and better facilitates gaseous management for the production of sulfuric acid. Reverberatory furnaces have been modelled in this comparison as they still represent a significant (although declining) proportion of processing capacity worldwide. Electric smelting has been included with reverberatory smelting as it is also a thermal process rather than an oxidation process with similar energy intensity to reverberatory smelting. Furthermore, there are very few electric smelters being used for primary production worldwide, so the environmental performance in this class will be dominated by reverberatory smelting operations. Hydrometallurgy Hydrometallurgical options including the heap leach / solvent extraction / electrowinning combination considered here, represent the most rapidly expanding class of technologies under development [5]. This is in part driven by a decline in the availability of higher grade ores (e.g. >2% copper) necessitating increased mining of lower grade ores (e.g. 0.5% copper). When lower grade ores are processed into concentrates, they can contain impurity levels which are too high to enable them to be processed in a smelter. In these cases, hydrometallurgical processing of the ore may be a viable option, as it can better handle contaminated feeds. Furthermore, hydrometallurgy is practised with both copper oxide ores as well as sulfide ores. Oxide ores are not processed in flash smelters as they lack sulfur in the feed, which is needed for the oxidation reaction which supplies heat to the furnace. In hydrometallurgical copper processing, the majority of operations are an acid heap leach followed by solvent extraction and electrowinning, although other processes based on bio-leaching and chloride leaching are gaining in popularity. New and emerging technologies will be included in the comparison at a later stage, after the current environmental profile of the industry is established in this paper.

4 DISTRIBUTION OF TECHNOLOGIES FOR PRIMARY PRODUCTION The magnitude and proportion of the various copper technologies used in each world region is depicted in Figure 2. The main points to note are: a mix of technologies are used in each region, with flash smelting being the dominant technology; SX/EW is most practiced in North and Latin America; the older reverberatory smelting technology still accounts for 10-15% of world production. Figure 2: Technologies used for copper refining across the world- size of circle relative to production (compiled with data from [2, 7, 8]) LIFE CYCLE ASSESSMENT OF ENVIRONMENTAL PERFORMANCE Choice of environmental performance assessment tool At this point we wish to select a tool for assessing the environmental performance of each technology. Numerous approaches exist, including LCA, Environmental Impact Assessment, Materials Intensity per Unit of Service, Cost Benefit Analysis and Materials Flux Analysis, to name but some. Each technique has particular strengths. However, their application is dependent on the stage of the project's development [9]. In this work, we are interested in characterising the average performance of a technology without knowledge of site-specific conditions. Unlike Environmental Impact Assessment, LCA has the flexibility to be used without site-specific information. LCA provides information on the performance of a process relative to its potential to contribute to recognised local and global environmental problems: e.g. Global Warming, Ozone Depletion, Acidification, Eutrophication, Human Toxicity, Eco- Toxicity and Smog. Description of Life Cycle Assessment In brief LCA involves: defining a boundary for the system under investigation; creating an inventory of inputs and outputs for this system; assessing the environmental impacts (Global Warming, Eco-toxicity etc.) attributable to these inputs and outputs, based on standard characterisation factors. The results may then be used in an improvement analysis, targeting areas of the process causing the most environmental impact. For a detailed description of LCA refer to SETAC [10]. Stewart & Petrie [11] more specifically outline the use of LCA in minerals processing. In this current work, a 'first-order' LCA is performed on three main classes of copper refining technologies: flash smelting, reverberatory & electric smelting and heap leach, SX/EW. At this level of detail, the following LCA impact categories were selected for inclusion in the comparison: Global Warming, Acidification, Eco-toxicity and Smog. Further information regarding these impact categories is given in Table 2. There are two lines of argument supporting this choice of categories. First, in all selected categories a significant effect was observed in the study, furthermore with significant variation in the effect seen between technologies. Secondly, the categories chosen demonstrate a breadth of effects which manifest both locally (e.g. Eco-toxicity) and globally (e.g. Global Warming) and which may arise directly from the copper

5 processing (e.g. Acidification from smelter emissions) or indirectly (e.g. Smog, from the burning of coal to provide electricity for the process). This representative selection highlights the usefulness of the LCA approach for describing both local and global effects, and with its wide system boundary, both direct and indirect effects. The chosen impact categories can be augmented by others such as overall energy and water consumption, both of which are included in the Chile / Australia case study presented later in the paper. This investigation extends the work of Norgate & Rankin [12] who undertook an LCA of copper processing, but considered only Global Warming and Acidification effects. This work also compares a greater number of technologies by including reverberatory smelting in addition to flash smelting and heap leach SX/EW. Table 2: Description of LCA impact categories significant in this study Impact category Description Impact manifested Global Warming Contribution to global warming due to the Greenhouse Effect. Globally Acidification Decreasing the ph of natural systems through mechanisms such as acid rain. Regionally Eco-toxicity In this paper, Eco-toxicity means toxicity to aquatic ecosystems. It is Locally reasoned that any terrestrial toxicity will eventually appear in groundwater and is covered under aquatic toxicity. Smog Atmospheric pollution in the form of smog. Locally FLOWSHEETS AND MODELS Flowsheets for flash and reverberatory smelting and heap leach SX / EW are presented in Figures 3, 4 and 5. REVERTS SILICADUST SLAG PROCESS SCRAP ORE DIESEL Open Cut Under ground Comminution Concentrate Matte Blister Copper Refined Copper Smelting Converting Electro-refining Evaporation FUEL OIL C Copper Product Slag Tailings C & Combustion Emissions Slag Electric Slag Cleaning Furnace Acid Plant Effluent (incl. metals) FLASH SMELTER Slag H 2SO 4 93% 7% Figure 3: Flowsheet of Flash Smelter REVERTS SILICADUST SLAG PROCESS SCRAP ORE DIESEL Open Cut Under ground Comminution Concentrate Matte Blister Copper Refined Copper Reverbatory Converting Electro-refining Evaporation FUEL OIL Furnace C Copper Product Slag C & Combustion Emissions Tailings Slag Acid Plant Effluent (incl. metals) REVERBATORY SMELTER H 2SO 4 5% 95% Figure 4: Flowsheet of Reverberatory Smelter ORE Crushed Ore Pregnant Liquor Loaded Solvent Cu Rich Electrolyte Leach Solvent Solvent Open Under Stripped Solvent Cu Poor Electrolyte (Heap) Extraction Extraction DIESEL Cut ground EVAPORATION (Loading) (Stripping) Crushing STEAM Electrowinning Waste Rock Acid Make-up Purge Stream Refined Copper Copper Product HEAP LEACH / SX / EW H 2 SO 4 Figure 5: Flowsheet of Heap Leach / Solvent Extraction / Electrowinning

6 From these flowsheets, the level of detail of inputs and outputs included in the models and the system boundary for each technology can be seen. It has been ensured that the level of detail of information used for each model is consistent. This allows valid comparisons to be made between technologies. In LCA terms, the system boundary applied to these technologies can be termed 'cradle-to-gate', that is, from initial extraction of the ore (cradle) to the processing of refined copper, out the 'gate' of the processing plant. In relation to the global material flows depicted in Figure 1, the system boundary includes mining and primary production. This investigation considers how improvements in environmental performance could be made through technology selection; each technology makes the same refined copper product and there is no need to consider the use of this refined copper beyond manufacture, as this is independent of the metals' production method. LCA studies which include the effects of copper consumption by further tracking its manufacture, use and final disposal would be termed 'cradle-to-grave'. No such studies are available at this time. Input-output models were developed using the technique of Stewart and Petrie [8]. In addition to the inputs outlined in Figures 3, 4, 5, the elements of Cu, Fe and S which are the principal components of interest in a copper sulfide ore were tracked through the process. All heavy metals/contaminants and the remaining gangue/waste rock were also monitored. The models can easily accommodate changes in ore grade, mining method (above ground/underground) fuel and electricity consumption and total throughput for each process. The inventory of inputs, outputs and products for each process is coupled with characterisation factors from the SimaPro LCA database which link the environmental burdens described by the inventory to quantified effects in the designated life cycle impact categories. PRINCIPAL ASSUMPTIONS Table 3 lists the principal assumptions used to define the performance of unit processes within the system boundary. The reference year is Sulfide ore was modelled for each technology, as this accounts for over 80% of copper mined worldwide. The ore grade, mining method and electricity supply are consistent across process options in order to assist comparison. Table 3: Principal modelling assumptions [4, 7, 12] Flash Smelter Reverberatory Smelter Heap Leach SX / EW Ore type Sulfide Sulfide Sulfide Ore grade 0.5% Cu 0.5% Cu 0.5% Cu method Open cut Open cut Open cut Overall Recovery 88% 88% 62% Total Electricity (kwh / t Cu) Electricity supply Coal Based Power Coal Based Power Coal Based Power Fuel Oil (t / t Cu) Diesel (t / t Cu) capture for H 2 SO 4 production 93% 5% H 2 SO 4 acid make up (t / t Cu) 1.7 MAIN ENVIRONMENTAL IMPACTS OF TECHNOLOGIES Figure 6 describes the environmental performance of each technology in four impact categories: Global Warming, Acidification, Eco-toxicity and Smog. Each category has one substance as a reference. For Global Warming, C is the reference and other compounds contributing to global warming are scaled accordingly, for example CH 4 has 21 times the greenhouse forcing potential of C. The representation in Figure 6(a) is hence a depiction of the global warming potential in equivalent kilograms of carbon dioxide per tonne of refined copper (kg C eq. / t Cu). The reference substance for acidification is sulfur dioxide ( ). For smog, POCP is the abbreviation for photochemical oxidation potential, and the reference substance is ethene. Eco-toxicity is expressed relative to the eco-toxicity of the reference substance, chromium (VI). Global Warming Figure 6(a) shows that flash smelting and reverberatory smelting have a similar global warming impact. Reverberatory smelting does not obtain energy from the burning of sulfides and consequently has a significant fossil fuel requirement to maintain high temperatures in the furnace. Flash smelting harnesses energy from the burning of the copper sulfide concentrates by adding oxygen to the furnace and requires only a small fossil fuel input for temperature control. However, oxygen manufacture requires considerable electricity, which using coal based power, results in an approximately equivalent overall global warming contribution. SX/EW has the highest global warming impact due to its high electricity requirement. Electricity consumption is much higher for electrowinning (in SX/EW) than for electro-refining due to electrowinning's high voltage requirement (~3 V) compared with electro-refining (~0.2 V) [7].

7 Acidification The acidification potential is significantly higher for the reverberatory furnace, due to its lack of adequate capture. While no is produced at the SX/EW plant, the associated acidification effect arises from the burning of coal for electricity generation. Eco-toxicity The eco-toxicity is highest for the reverberatory smelter due to its high fuel oil consumption. Smog Smog arises mainly through the burning of diesel associated with mining. Without an LCA approach, such an environmental impact could be easily overlooked as it is not manifested on-site at the copper processing facility. Balancing the four impacts The question of which environmental effect is most significant depends on its importance to the decision maker. Global warming currently has a high profile as an environmental effect of concern within the scientific and wider community. However, it is prudent to afford it due consideration along with other environmental effects, rather than as the only issue of importance. LCA has been used here as a good starting point for a more balanced approach to decision making. Global Warming Impact from 1 t copper production Eco-toxicity Impact from 1 t copper production 25, ,000 kg CO2 equivalent / t Cu (a) 20,000 15,000 10,000 5,000 0 REVERB FLASH SX / EW Refining Eco-toxicity units / t Cu (b) 250, , , ,000 50,000 0 REVERB FLASH SX / EW Refining Acidification Impact from 1 t copper production Smog Impact from 1 t copper production kg SO2 equivalent / t Cu 3,000 2,500 2,000 1,500 1, Refining kg POCP equivalent / t Cu Refining (c) REVERB FLASH SX / EW (d) REVERB FLASH SX / EW Figure 6: Most significant environmental impacts from LCA for production of 1 t refined copper DISTRIBUTION OF ENVIRONMENTAL IMPACTS By combining the environmental performance models of individual technologies (Figure 6) with the regional production data for each technology (Figure 2), Figure 7 gives a region-specific indication of the major environmental effects, both local and global, occurring as a result of primary copper production worldwide. The column size in Figure 7 indicates the percentage of the total effect for that impact category to which either the mining activities or primary production activities are responsible for each region. The magnitude of the total effect for each impact category is listed in the legend in Figure 7. It can be seen that the percentage contribution to acidification from refining processes is low in Oceania regions where no reverberatory smelters are operating. Conversely, acidification stands out as a major effect, relative to others, in Africa, Central and East Asia, which still operate a sizeable capacity of reverberatory smelters. The large acidification effect in Latin America is just as much a function of the large production capacity in that region, as of the mix of technologies. Global warming is most significant in Latin America, the largest producing region, which also has a considerable amount of energy intensive SX/EW operations in place. The importance of Figure 7 is that it presents an overview of the distribution of environmental impacts from copper processing worldwide, from which changes to the status quo can be compared. Linking the

8 results back to copper consumption (Figure 1), it prompts the further need for large consuming regions such as Europe who only have a small burned associated with copper mining and refining to assume more responsibility for the copper used in its economy which is extracted and refined elsewhere. Figure 7: Distribution of Global Warming, Acidification, Eco-toxicity, Smog for mining and refining COUNTRY ANALYSIS: CHILE / AUSTRALIA COMPARISON This section explores a more detailed analysis of the technologies in two specific countries: Australia, and Chile the world's largest copper producer. In response to the Kyoto Protocol, there is increasing pressure on countries to examine their contribution to global warming. The case study presented here considers the ore grade and electricity mix for each technology in both countries. These are two of the most important factors affecting global warming, which, in addition to the copper processing technology itself, have a significant impact on the overall environmental performance of the process. Table 4 lists the principal assumptions for the models in this case study. All other unspecified assumptions (except for total electricity usage) are as described in Table 3. The results of the environmental performance modelling are presented in Table 5. Table 4: Principal assumptions for Chile / Australia Comparison REVERB Chile FLASH Chile FLASH Australia SX / EW Chile SX / EW Australia Ore Grade (% Cu) Electricity Mix 70% Hydro 30% Coal 70% Hydro 30% Coal 100% Coal 70% Hydro 30% Coal 100 % Coal Table 5: Utility consumption and environmental impacts for the production of 1 tonne refined copper product REVERB FLASH FLASH SX / EW SX / EW Australia Chile Chile Australia Chile Water (m³) Energy (MJ) 59,000 44,000 70,000 82,000 81,000 Global Warming (kg C eq) 4,300 3,300 8,400 6,200 10,600 Acidification (kg eq) 2, Eco-toxicity (Eco-toxicity units) 240,000 89,000 97,000 48,000 26,000 Smog (kg POCP eq)

9 The results of the case study highlight a number of significant points arising from the difference in ore grade and electricity mix between the two countries. Energy use in SX/EW processes is much higher than for reverberatory and flash smelting. Chile's energy use per tonne of copper is the highest of all processes due to it utilising the lowest grade ore. However, the global warming effect of Chile's SX/EW process is still less than for both the SX/EW and flash processes in Australia. This is due to Chile's high percentage of electricity sourced from hydropower which in this study is assumed not to contribute to global warming. While the use of hydropower in Chile reduces the global warming burden of its SX/EW process, one impact which it does not assist in reducing is smog. As a direct result of the low ore grade used for SX/EW in Chile which requires more diesel for mining and ore transport the smog effect is much higher than for SX/EW in Australia. Water consumption for SX/EW in Australia is lowest due to its high ore grade. This analysis, highlights the usefulness of integrating regional circumstances into the assessment. Technology choices can then be supported with an understanding of local conditions and region-specific concerns for particular environmental effects. SCENARIO ANALYSIS: REPLACEMENT OF REVERBERATORY SMELTERS Having established the environmental performance for each technology, it is possible to use this information to investigate 'what if' scenarios, either on a global or regional basis. As a demonstration of this approach, a scenario is considered where the world's ageing reverberatory smelters are replaced with either: heap leach/sx/ew; or flash smelting. The change in environmental impact of such an outcome is then determined. Production figures for each technology are given in Table 6. Table 6: Primary production of refined copper in 1999 by processing route [2, 8] Flash Smelter Reverberatory Smelter Heap Leach SX / EW World Production 1999 (t Cu) 8,000,000 2,000,000 2,300,000 The results of the scenario analysis are presented in Figure 8. The effects in Figure 8(a) are relative to the effects from reverberatory smelting only. In Figure 8(b) the effects are relative to the effects for world production from all technologies. A score of 1.0 means the effect is the same as when the reverberatory furnace was used. In the comparison of flash smelting with reverberatory smelting in Figure 8(a), it is observed that in all environmental impacts, flash smelting has a lower environmental impact than for reverberatory smelting. SX/EW scores even lower than flash smelting for acidification and eco-toxicity yet higher (even that the reverberatory smelter itself) for global warming and smog. The decision maker posed with the question of which technology should be implemented to replace reverberatory furnaces, is now faced with a dilemma based on this information. In practice, economic and social factors would also enter the decision making process, but for the moment consideration will remain with the environmental information at hand. In essence, there is a trade-off to be made between lower acidification and eco-toxicity but higher global warming and smog with SX/EW and low to mid-range scores in all categories for flash smelting. If all impact categories were of equal importance, then it would seem appropriate to select flash smelting. However, if local residents or regulators were consulted about a preferred process, SX/EW may be favoured as its site-specific impacts are less. Eco-toxicity, which manifests locally, is less, and acidification effects from the site itself are negligible, as no is formed in the process. In fact the acidification effect attributed to SX/EW, like the smog and global warming effects, arise mainly from coal based power generation used to supply electricity for the process. It is quite possible that the power station is located a significant distance from the copper processing facility, in which case the local community may not ascribe the same concern to effects which occur elsewhere. It is a difficult task for any decision maker to balance concerns near and far with effects being manifested locally and globally. In the current environmental debate, there is a large focus on reducing global warming which may over-ride other factors, leading to the selection of flash smelting as a preferred option. In reality, this is likely to not always be practicable given the declining grades of copper ores available, which better lend themselves to be processed via hydrometallurgical routes. In this climate, a hydrometallurgical plant coupled with a renewable energy source would stand out as an attractive option. Figure 8(b) reveals that the introduction of either technology will greatly reduce the acidification burden for the world, due to copper refining. In the case of global warming and smog, the choice of either technology effects only a minor change in the total burden attributable to copper processing worldwide. Going beyond the specific details of this scenario, a valuable approach has been demonstrated which better informs the decision maker about the local and global environmental effects of copper technologies based on a Life Cycle approach.

10 Figure 8: Comparison of impacts arising if world production via Reverberatory smelting was replaced by either Flash smelting or Heap leach SX/EW These results present a vital link between the environmental copper processing technologies and the ability to make informed technology choices which are consistent with sustainable development. CONCLUDING REMARKS A baseline environmental performance has been established for the primary production of copper worldwide. Future work will also include secondary production and recycling. This paper has shown how the material flows of copper can be combined with an assessment of technology-specific environmental performance based on LCA, to allow major local and global environmental impacts to be mapped worldwide. Importantly, both local and global effects are monitored. The information has been subsequently used to explore the environmental trade-offs which apply when considering comparisons between specific countries and specific technology replacement scenarios, including the replacement of reverberatory smelters with newer technologies. This approach is recommended generally for establishing environmental performance information for mineral processes. If this is coupled with equivalent detail of economic and social analysis, more informed decisions around technology selection can be made which will result in progress toward sustainable development for the minerals industry. REFERENCES 1. GMI (2000), 'The Minerals and Sustainable Development (MMSD) Analysis: Why is this work needed', Global Initiative, Accessed from the Internet, 1st March, Edelstein, D. (1999), Minerals Yearbook: Copper. United States Geological Survey: Washington. 3. Hilson, G. (2000), 'Barriers to implementing cleaner technologies and cleaner production practices in the mining industry: a case of the americas'. Minerals Engineering, 13(7), Riekkola-Vanhanen, M. (1999), Finnish expert report on best available techniques in copper production and by-production of precious metals. Finnish Environment Institute: Helsinki. 5. Davenport, W. (1999), Copper extraction from the 60's into the 21st century, in Copper 99-Cobre 99, G. Eltringham, N. Piret, and M. Sahoo, Editors. The Minerals, Metals & Materials Society: Phoenix. p Hanniala, P., Helle, L., & Kojo, I. (1999), Competitiveness of the Outokumpu flash smelting technology now and in the third millennium, in Copper 99-Cobre 99, D. Gerrge, et al., Editors. The Minerals, Metals & Materials Society: Phoenix. p Biswas, A. & Davenport, W. (1994), Extractive metallurgy of copper. 3rd ed. Oxford: Elsevier. 8. Moreno, A., ed. World copper databook. 4th ed. 1999, Metal Bulletin Books: Surrey, UK. 9. Stewart, M., Basson, L., Alexander, B., & Petrie, J. (2000) Allied tools to LCA in the process industries. in Second national conference on Life Cycle Assessment February, Melbourne. 10. Society for Environmental Toxicology and Chemistry (SETAC) (1992), Guidelines for conduct of LCA peer review draft paper. SETAC: Penascola. 11. Stewart, M. & Petrie, J. (1996), Life cycle assessment for process design- the case of minerals processing, in Clean technology for the mining industry, M. Sanchez, F. Vergara, and S. Castro, Editors: Concepcion. 12. Norgate, T. & Rankin, W. (2000) Life cycle assessment of copper and nickel production. in MINPREX September, Melbourne, Australia.