Hydrometallurgy 94 (2008) 58–68

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Hydrometallurgy j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / h y d r o m e t

Progress after three years of BioMinE—Research and Technological Development project for a global assessment of biohydrometallurgical processes applied to European non-ferrous metal resources D. Morin a,⁎, T. Pinches b, J. Huisman c, C. Frias d, A. Norberg e, E. Forssberg f a

Ecotechnology Unit, Environment and Process Division, BRGM, BP6009, 45060 Orléans Cedex 2, France Mintek, Randburg, South Africa c Paques, AB Balk, The Netherlands d Técnicas Reunidas, Madrid, Spain e Skeria, Skellefteå, Sweden f Luleå University, Luleå, Sweden b

A R T I C L E

I N F O

Available online 6 June 2008 Keywords: Biohydrometallurgy Biomining Bioleaching Non-ferrous metals Gold Copper Nickel Zinc European integrated project

A B S T R A C T BioMinE is an integrated project under the sixth framework programme of research supported by the European Commission, which started in November 2004 and will last until October 2008 (Ref. NMP2-CT2005-500329). It is dedicated to the evaluation of biohydrometallurgy to improve the exploitation of the European non-ferrous metal resources in a sustainable way. At the end of 2007, the Consortium of BioMinE comprised 37 partners from industry (13 including 6 Small or Medium Enterprises), research organisations (8), universities (15), and government (1). The participants are from 13 EU member states and from Serbia and South Africa (INCO Countries). For more details see http://biomine.brgm.fr. The three main kinds of resources considered for bioleaching studies are: - Copper polymetallics (concentrates and tailings), - Zinc polymetallics (zinc and zinc polymetallic concentrates) - Secondary wastes (tailings, rock and metallurgical wastes, etc.) For each of these resources, amenability studies of application of bioleaching technologies by various approaches have been undertaken or still ongoing. Further processing assessment will be conducted up to the demonstration scale. Technological improvements have been made to apply bioleaching in the context of the European resources in terms of complexity and sustainability requirements. The relevant fundamental studies covering bio-prospecting, molecular ecology, biochemistry, and genetics areas aimed at improving the understanding and the control of the selected technologies have given original results. Much progress has also been obtained in the use of the microbial sulfate-reducing process to polish effluents and to recover metals from leachates containing low concentrations of metals. The finding of micro-organisms thriving at low and high temperature, respectively 8 and 65 °C, leads to an extension of the application range of the process. It has been also observed that this process could be pushed down to pH 4.5 and 4 creating opportunities of selective metal recovery as metal sulphides. It has also been demonstrated that sulphate can be removed at high concentrations, as well as arsenic or selenium. The next step in this work is pilot testing. This will allow to determine scale-up criteria and to assess the residual metal concentration under actual conditions. The pilot-scale demonstration operations, as well as the techno-economic and comparative sustainability assessments will be achieved during 2008, the last year of the project. The prototypes of the learning objects for training about biohydrometallurgy accessible by internet have been elaborated. A public output of this work is accessible at http://wiki.biomine.skelleftea.se/wiki. The basic knowledge thus delivered is aimed at disseminating the understanding of the origins and use of biohydrometallurgy. Contacts with mining operators in Europe have been taken and collaboration schemes have been established in various ways according to the respective contexts. When a high potential of technical

⁎ Corresponding author. E-mail addresses: [email protected] (D. Morin), [email protected] (T. Pinches), [email protected] (J. Huisman), [email protected] (C. Frias), [email protected] (A. Norberg), [email protected] (E. Forssberg). 0304-386X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.hydromet.2008.05.050

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involvement could be foreseen, a direct participation of the mining operators in the project was favoured, this led to integrate KGHM (Pol), Boliden (Sw) and Copper Institute of Bor (Serbia) into the consortium of partners. When no direct technical commitment was conceivable at the first stage, collaboration was established with companies with the most urgent requirement to have access to the relevant resource. © 2008 Elsevier B.V. All rights reserved.

1. Introduction The European non-ferrous metals mining industry has initiated and developed the BioMinE project as they identified the need to find new processes for metal extraction from resources of today and of tomorrow. Currently, the extracting and metallurgical industries can cope with the huge demands of the emerging countries but the prices of metals have soared at unexpected sky-high values. Many metal market analysts predict that a new area has begun and that the prices will remain high for an extended period. They will most probably not go down to levels before the recent increase in metal prices. Large orebodies of natural metal resources that can be processed easily with conventional techniques are becoming scarce. In addition, recently discovered deposits have a more complex mineralogy than before. In the present context, some mining regions of the world are becoming wealthier as their resources are still relatively abundant and have the right characteristics to serve as feed for current metallurgical technologies. Chile is an example in case of copper. Others regions, like Europe, are (nowadays) poor in primary resources and have a growing economic dependence on substances that are absolutely necessary to their industry. From the point of view of the European extractive metallurgy, Europe has two converging ways to loosen the grip. One is to discover new resources on its own territory and the other is to develop its own technologies for its own resources. By the means of exploring all the options for a sustainable development and investing in research in innovative technologies able to deal with difficult-totreat resources, Europe is getting ahead for the production of metals in the future. Conventional technologies to extract base metals are mainly based on pyrometallurgy. This is, compared to hydrometallurgy rather restricted with regard to ranges of metals grades and impurities it can process. Hydrometallurgy has provided many alternatives that are more or less universally applicable at various costs and profits. The aim to keep elements in their aqueous phase reduces the risks of uncontrolled emissions. Many technologies have been developed to selectively recover impurities and valuable metals. However, the efficiency of these technologies has a cost in energy and in complexity. Biohydrometallurgy results in lower energy expenses and simplifies the treatment of complex materials due to the catalytic effect exerted by the microbiological processes on the oxidizing reactions of the metal-bearing sulfides. This initial picture of the base metal metallurgy sector guided the designers of the BioMinE project in the organisation of the project focused on the evaluation of processes to be applied in Europe to European resources. BioMinE is an integrated project under the sixth framework programme of research supported by the European Commission, which started in November 2004 and will last until October 2008. At the end of 2007, the Consortium of BioMinE comprised 37 partners from industry (13 including 6 SMEs), research organisations (8), universities (15), and government (1). The participants are from 13 EU member states and from Serbia and South Africa (INCO Countries). For more details see http://biomine.brgm.fr. The names of the organizations partners of BioMinE, which are quoted in the text, are listed in Table 1.

After having described in a previous paper the context and the objectives of the project at its beginning (Morin et al., 2006), this one gives an overview of the progress of BioMinE after three years. 2. Selection of resources and roadmap for the RTD studies Not all the European resources would be good candidates for the assessment of the application of biotreatments and a rational screening was required. Two objectives had to converge. The first was to characterise what a typically European resource amenable for biotreatment would mean. The second was to make available samples of such typical resources for testing within the project. The first was mainly based on existing knowledge and the use of data base of geological information. This was done during the first year of the project in the frame of the workpackage 1 of the project with the support of the know-how of the experts in the application of the relevant biotechnologies (Lips and the BioMinE Consortium, 2006). This screening was unique for Europe and was even the first one of its kind in the world. The result was a selection of potential resources to which application of the biotechnologies could be the solution for a more profitable exploitation than with conventional technologies. A roadmap of the major part of the work in the project could then be designed. Since the first year it has thus been agreed that low-grade complex copper and zinc concentrates and secondary resources of the mining activities would be the targeted resources of the project. The existing biotechnologies that fit to the European targets were identified like for example tank leaching for copper concentrates. New technologies to be developed for new resources were determined, for instance indirect bioleaching for certain zinc concentrates. New concepts of equipment to fit the characteristics of low-grade resources had to be elaborated with for example the design of a low-cost bioreactor. The possibility to recover more metal from process and bleed streams by integrating a biotechnological treatment based on metal sulfide precipitation was planned to be assessed. Some fundamental research has been isolated at the beginning of the project that would allow a progress for the development of biohydrometallurgy specifically in Europe. An example is the study of genomics. This is justified by the expectation that this knowledge will clarify the real capacities of the micro-organisms. Furthermore, Europe has the potential to carry out consistent work in this area on the long term. The investigation in the bio-flotation technique has the same kind of justification. There is clearly no hope to develop a commercial application within the time frame of BioMinE but on the long term Europe will benefit of the advantages of a real breakthrough if viable technology could result from the research in this area and if interesting spin-off could be developed. However, some other fundamental work could be bent to the objectives of the project in terms of resources like the search for new species and the design of consortia for the treatment of selected resources in predefined conditions. More practically, from the beginning of the project a specific effort was made to better use molecular techniques for identifying and monitoring the population of micro-organisms with the aim to identify what each technique will be most appropriate to obtain specific information. The second objective of workpackage 1 (WP1) at the end of the screening of the resources was to make benchmark resources available. This was possible through a regular dialogue with the mining operators recognized as the potential end-users of the

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Table 1 List of the 37 BioMinE organizations participating in BioMinE project in 2007 Partner name and short name

Countries

Bureau de Recherches Géologiques et Minières (BRGM) Tampere University of Technology (TUT) Technische Universitaet Berlin (TUB) Universitaet Duisburg-Essen (UDE) Institute of Geology and Mineral Exploration (IGME) National Technical University of Athens (NTUA) Bioclear B.V. (Bioclear) Paques B.V. (Paques) Wageningen University (WU) Instityt Metali Niezelaznych (IMN) Instituto National De Engeharia (INETI) De Beers Consolidated (DBCM) Mintek (Mintek) University of Cape Town (UCT) University of Stellenbosch (Stellenbosch) Universidad Autonoma de Madrid (UAM) Luleå University of Technology (Ltu) MEAB Metallextraktion AB (MEAB) Umeå University (Umu) CellFacts Instruments Ltd (CIL) Imperial College of Science and Technology (Imperial) Rio Tinto (Rio Tinto) University of Wales, Bangor (UWB) University of Warwick (Warwick) Tecnicas Reunidas (TR) Outotec (OTT) Umicore (Umicore) Skeria Untvecklung, Skellefteå (Skeria) Centre National de la Recherche Scientifique (CNRS) University of Stuttgart (USTUTT) PE International (PE Int) Institute for Non-ferrous and Rare Metals (IMNR) Milton Roy Mixing (MRM) New Boliden (Boliden) Copper Institute Bor (CIB) KGHM Polska Miedź, S.A. (KGHM) University of Seville (US)

Fr Fin Ger Ger Gr Gr Nl Nl Nl Pol Port RSA RSA RSA RSA Sp Sw Ger Sw UK UK UK UK UK Sp Fin Bel Sw Fr Ger Ger Rom Fr Sw Ser Pol Sp

technologies developed. By capturing the interest of Boliden, KGHM, Rio Narcea, Somincor, Lunding Mining, Bor District and some other companies, a large part of the major operators in this field in Europe could contribute in giving access to samples of the relevant resources. This is during the second year of the project that the work plan on applications could be drawn up per resource and per technology from the amenability test work (Workpackages 2 and 3) to the possible demonstration of validated treatments (Workpackage 4). Since then, this roadmap (based on ‘Exploitable results’) has been the main structure for the activities of resources assessment from the technical point of view and the guide for the exploitation of applied results of the project. In the same time, the structure of management of the exploitable results has been much improved on the basis of a screening of the main potential outcomes of the project aligned with the vision of the applications on which our work has been focused. The implementation of the concept of clusters of partners associated in the development of specific results to exploit has been undertaken and formalized during the third year of the project (Workpackage 5). 3. Bioleaching From a practical point of view, two dominant aspects have characterized the project at the end of the third year: • The first is the achievement of a large bulk of preliminary assessments of resources and technologies screened and selected during the two first years of the project (in WP1, 2 and 3). • The second is the focus on bench-scale experiments towards pilotscale demonstration operations on the selected resources.

In the background of this major stream of development activities, research work has been continued on specific subjects of interest mainly in the area of bioleaching and for the benefit of a better understanding and control of the processes. Test work on the application of bioleaching has been carried out in the frame of WP2 for quite a large range of European resources with the various techniques previously selected for their presumed appropriateness. Direct or indirect bioleaching were assessed on Ni– Cu, Cu, Zn, Pb and Zn/Pb concentrates and wastes (tailings and slags). The technical results of the bench-scale studies are satisfactory and generally confirm the validity of undertaking operations at pilot scale and subsequent calculation of costs at a pre-feasibility level for the technologies applied to the benchmark resources selected. The benchmark resources concerned are particularly a Ni–Cu concentrate of the Aguablanca mine (Spain, Rio Narcea), a Cu concentrate of the Majdanpeck-Veliki Krivelj mines of the Bor district (Serbia), Zn and Pb concentrates of the Tara Mine (Ireland, Boliden), and secondary resources of Bor and Lubin (Poland). Fundamental issues about bioleaching which have been addressed for their pertinence in the case of European context have significantly progressed towards a better efficiency and sustainability of the applications of the processes. A non-exhaustive selection of these technical studies is as follows: • Use of wastes as reagents • Enhancement of bioreactors for regenerating ferric as oxidant in the configuration of the indirect bioleaching process • Prevention of passivation of chalcopyrite during bioleaching • Biostabilisation of arsenic in solid bioresidues • Reduction of elemental sulfur in the solid residues of bioleached refractory gold ores to lower the consumption of cyanide required for the recovery of the precious metal • Determination of the operating conditions of bioleaching of slags and tailings • Identification and characterisation of low-temperature microorganisms • Understanding of the biochemical mechanisms of tolerance to high concentrations of inhibiting elements • Selection of bacterial cultures able to tolerate high Zn concentrations in solution (up to 75 g/l). 3.1. Tank bioleaching of Cu and Cu polymetallic concentrates The main thrust of the RTD activities using the copper concentrates was conventional “direct” tank bioleaching. Furthermore, it was clear that the use of thermophilic cultures enabling faster leach kinetics, particularly for the leaching of chalcopyrite, would be a key requirement. Taken together with downstream processing studies carried out under workpackage 4, these results were being used for preliminary techno-economic evaluations to plan the scope of integrated piloting campaigns to be completed during the latter part of year 3 and year 4 of the project. The Aguablanca Cu–Ni concentrate (Cu; 7.5%, Ni; 5.6%, Fe; 32.7%, S=; 32.3%) had also been subjected to preliminary amenability testing using “indirect” bioleaching. However, for this concentrate, technoeconomic studies indicated that conventional “direct” bioleaching was the preferred technology. While Ni (pentlandite) and Cu (chalcopyrite) bioleaching have been studied fairly extensively in the past, there have been no known published studies on the bioleaching of polymetallic Ni–Cu concentrates. The current biohydrometallurgical studies therefore represent novel technology development. Bioleaching design criteria for the piloting campaign were based on an extended period of laboratory and bench-scale RTD activities. This confirmed the requirement for use of thermophilic cultures for effective bioleaching of the chalcopyrite component. Novel bioleaching operating conditions and control

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Fig. 1. CARD-FISH (Catalysed Reporter Deposition–Fluorescent In Situ Hybridization) hybridized bacteria with specific probes in R2. A: CARD-FISH with THC642, specific for members of the A. caldus specie. B: CARD-FISH with LEP154, specific for members of the L. ferriphilum species. Tendency of L. ferriphilum to form clusters can be observed (B) against the planktonic A. caldus (A). Scale bar, 2 µm (Universidad Autonoma de Madrid).

strategies have been identified which have the potential to significantly increase the rates of Cu and Ni leaching. It has also been shown that use of these operational strategies has the potential to reduce process (energy) costs by allowing control of chalcopyrite-sulfide oxidation (elemental sulfur production) and of the amount of pyrite oxidised. The bench-scale and integrated piloting results on the copper concentrate will also provide the experimental data for the ongoing development of a tank bioleaching model being undertaken by the University of Cape Town. Up to now UCT have tested the model for mesophilic bioleaching systems and this is now being expanded to include thermophilic systems, where the model would allow investigation of hypothetically different reactor configurations and operating strategies. During the third year of the project, samples of copper concentrates were received from the Majdanpek and the Veliki Krievelj mines of RTB-Bor, Serbia. A sample of copper sulfide concentrate from RTBBor smelter slag was also received. Initial tests have confirmed that all these resources show good amenability to bioleaching. Bench-scale bioleaching development and optimisation work has now started with the intention of generating design criteria for an integrated piloting campaign using the RTB-Bor Cu resources to be started in early 2008. INETI has also carried out laboratory bioleaching amenability testing

on the Neves Corvo chalcopyrite concentrate using thermophilic cultures isolated and characterised from hot springs in the Azores. In the Aguablanca Ni–Cu and the Majdanpek and Veliki Krievelj Cu concentrates, the major copper mineral is chalcopyrite. This is also the case for other BioMinE concentrate resources such as those from the Boliden district and Neves Corvo. Chalcopyrite does not generally leach well in acid-sulfate leach environments due to surface passivation and the use of thermophilic cultures (up to 80 °C) is usually necessary to achieve acceptable leach kinetics. As a result, further RTD activities have now started to provide molecular tools to identify and enumerate thermophiles in the high-temperature copper bioleaching systems. Specifically, Q-PCR (Quantitative Polymerase Chain Reaction, used by Bioclear) and CARD-FISH (Catalysed Reporter Deposition–Fluorescent In Situ Hybridization, used by Universidad Autonoma de Madrid, see Fig. 1) methods will be developed using samples generated during the ongoing piloting and bench-scale research activities. In addition, Bioclear are developing a biomolecular tool for monitoring the level of microbial “activity” and Warwick University functional gene probes to investigate and monitor specific activities such as Fe and S oxidation (Bathe and Norris, 2007). The role of extracellular polysaccharide and cell attachment in bioleaching

Fig. 2. Combination of atomic force and epifluorescence microscopy for visualization of leaching bacteria on pyrite developed by the University of Duisburg-Essen.

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systems using thermophiles is presently unknown. Related research is therefore being undertaken in conjunction with the bench- and pilot scale using Cu concentrates mentioned above in particular in using the method of combination of atomic force microscopy and fluorescent in situ hybridisation developed by the University of Duisburg-Essen (illustrated in Fig. 2, Mangold et al., 2008). Other innovative approaches to bioleaching of copper concentrates are being undertaken by Boliden and Technical University of Lulea (Ltu). The main objective here is to investigate bioleaching strategies for the selective removal of impurities such as arsenic and antimony from copper concentrates. A broad range of research investigations related to bioleaching consortia applicable to the various BioMinE resources has now been completed. It should be noted that prior to BioMinE there was very little published information available on the microbial consortia occurring in tank bioleaching processes. A major study by UWB (Johnson et al., 2007) has investigated the structure of consortia established on eleven types of sulfide concentrates using 23 different species and strains. These studies show that a “one size fits all” approach is inappropriate and that there may be considerable benefits arising from the use of optimised microbial consortia for specific concentrates and the operating conditions chosen with scenarios as illustrated in Fig. 3. Another relevant finding from the microbial genetics studies at Stellenbosch University is that metals resistance in the microbial consortia is aided by mobile metal resistance genes, which may be recruited from the horizontal gene pool acquired via metal resistance plasmids or transposons (Tuffin et al., 2006). It appears that genes conferring high levels of resistance to arsenic previously found in stains of Leptospirilli from South Africa are also present in isolates from different parts of Europe (Kloppers et al., 2007).

Fig. 3. Different approaches for optimising and designing bioleaching consortia (University of Wales, Bangor).

objective has been to devise strategies that promote bacterial iron oxidation but which might significantly reduce the level of bacterial sulfur oxidation. The strategies investigated were (i) use of a lowresidence-time bioleaching process fed with an Fe-oxidising culture (bio-generator concept) (Ltu, Boliden), (ii) the use of various selective bioleaching process operating conditions (Mintek), and (iii) the use of metabolic blockers (Umu, UDE and CNRS). To date, only the first approach has provided indications of potential success. Some partners (CNRS, UDE and Umu) are now adopting a genomics approach to better define sulfur oxidation pathways and consequently ways in which these might be manipulated. RTD activities by IMNR have established an effective tank bioleaching process to treat the Baia Mare Pb–Zn-precious metals concentrate. The major emphasis over the reporting period has been to provide sufficiently large residue samples to Técnicas Reunidas for Pb and precious metals recovery work under workpackage 4.

3.2. Tank bioleaching of Zn and Zn polymetallic concentrates 3.3. Tank bioleaching of Au concentrates For the zinc and zinc polymetallic RTD activities, the main subject was the application of indirect bioleaching technology. A key challenge that had been successfully addressed was the intensification of the ferrous iron bio-oxidation step in the process. A preliminary techno-economic assessment for indirect bioleaching of zinc and zinc polymetallic concentrates was produced, which indicated some scaleup challenges to be addressed but indicated the potential for favourable economics. For comparative purposes, RTD on direct tank bioleaching was also carried out. In this case, three technical challenges were identified to achieve improved economics. These were the need for microbial tolerance to high quantities of silver commonly occurring in these types of concentrates, maximising microbial tolerance to high Zn tenors which could facilitate direct electrowinning of Zn metal (eliminates solvent extraction step), and a reduction in energy requirements by control of the amount of sulfide oxidised to sulfate. A zinc concentrate from the Boliden Petiknäs mine, Sweden, was supplied and used in these studies. While the ability to control sulfide oxidation had not shown any success, good progress was made in adapting the culture to higher metal concentrations. Due to the lower value of Zn compared to Cu and Ni, the key objective for ZnS bioleaching is to minimise costs associated with the Zn bioleaching-metals recovery circuit. One way to do this is to maximise the Zn tenor obtained to the extent (N50 g/l) that a simplified hydrometallurgical circuit involving direct electrowinning of Zn might be an option. Bench-scale testing at Mintek using mesophilic and moderately thermophilic cultures bioleaching Petiknäs Zn concentrate achieved Zn concentrations of 75 g/l. An alternative approach investigated is to limit the energy costs for sulfide oxidation by promoting sulfide oxidation to the level of elemental sulfur, rather than its complete oxidation to sulfate. In the “indirect” bioleaching process this is achieved because the chemical oxidation of base metal sulfide yields largely an elemental sulfur product. In “direct” bioleaching the

Bioleaching of refractory sulfide gold concentrates is a commercialised technology and the challenges under BioMinE have been to address environmental issues arising from the use of cyanide to recover the gold and the safe disposal of arsenic-containing waste residues. Good progress had been made in the use of thermophilic cultures capable of reducing final residue sulfur content and a concomitant decrease in cyanide consumption. Gold concentrates derived from the Petiknäs Norra mine, Sweden and the Sheba mine, South Africa, have been employed in these studies. Other ideas introduced were the use of bioleaching process configurations which might achieve selective leaching of arsenopyrite over pyrite, where arsenopyrite is the main gold-hosting mineral. The work on bioleaching of gold concentrates by Mintek on Sheba and Petiknäs Norra gold concentrates in bench-scale piloting using mesophile, moderate thermophile and thermophile cultures has been completed. Results using a thermophile culture have identified optimum operating conditions which allow for at least a ten-fold decrease in cyanide consumption for gold leaching compared to the current commercial process using the lower temperature cultures. This results from a significant reduction in the bioleach residue elemental sulfur content. The ability to minimise cyanide usage may be a significant factor in meeting statutory environmental impact requirements for the use of this technology in Europe. The cyanide consumptions obtained were at or below the levels normally associated with non-sulfide-free-milling gold ores. The results also show final waste leach liquors where the level of As(III) is twenty-fold less than the minimum achievable using the lower temperature cultures. A related technology advance, which has been further consolidated over the reporting period, is conversion of waste bioleach solids to “controlled low-strength materials” (CLSM) with application for encapsulated systems underground (studied by

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Imperial College see Bouzalakos et al., 2008 and Chan and Dudeney, 2008). This would facilitate potential structural applications as an alternative to conventional disposal in tailings dams. In the longer term, the ongoing studies being carried out by Stellenbosch on the molecular biology of metals resistance mechanisms may have significant impact on developing strategies for designing and operating bioleaching processes to tolerate high concentrations of inhibitory metals such as arsenic found in refractory gold concentrates. Similarly, the progress being made by Warwick, CNRS and Umu in understanding and cellular sulfur oxidation mechanisms will impact on the development of process options for sulfur management. At the biological level, the major immediate contribution, which is closely related to the foregoing research areas, in advancing refractory Au bioleaching technology is the ability to monitor and characterise the microbial consortia and relating the changes to consortia composition to the concentrate characteristics and to the process operating conditions (d'Hugues et al., 2007). 3.4. Indirect tank bioleaching of base metal concentrates BioMinE is addressing the development of the bio-oxidation unit operation in the indirect bioleaching process i.e. an intensive process for bacterial oxidation of ferrous to ferric iron. Tempere University of Technology and Outotec participated in progressing the development of a high-rate fluidised bed bioreactor with optimum performance with respect to Fe tolerance and low pH (b1.0) to maximise Fe solubility (Puhakka et al., 2007). Process operation using a Leptospirillum ferriphilum dominated fluidised bed reactor at an Fe concentration of 60 g/l was feasible. This has been extended to experimentation coupled to kinetic modelling addressing the simultaneous effects of Fe3+ concentration and various base metals (Ni and Zn) on reactor performance. These data were used by Outotec to assess the techno-economic feasibility of applying indirect bioleaching to treat base metal ores and concentrates and as the basis for comparison with different technology processing options. Special focus was to compare and evaluate the techno-economic aspects of indirect bioleaching with other process options for treating the Finnish low-grade Ni concentrate from the Hitura mine. Conclusions reached by Outotec to date are that indirect bioleaching will require optimum project scenarios for financial success. University of Seville has been collaborating with Técnicas Reunidas in a similar way to develop an enhanced bio-oxidation reactor for ferric iron production. In this case the RTD activities have focussed on bioreactor culture adaptation simultaneously to high ferrous iron and Zn. These activities are being carried out primarily as a contribution to the integrated piloting campaign and techno-economic study for indirect bioleaching of zinc sulfide concentrates. 3.5. Heap bioleaching of base metal sulfide ores While no significant European target resources had emerged at the beginning of the reporting period, it is recognised that one potential opportunity for heap bioleaching in Europe is heap bioleaching of lowgrade chalcopyrite-containing ores. In common with tank bioleaching of chalcopyrite-containing concentrates, the challenge for heap bioleaching is the slow copper leaching kinetics due to the passivation of the chalcopyrite mineral surface. For this reason, a testwork programme was developed and started by Outotec to investigate the passivation phenomenon and to develop methods for potential process management procedures to overcome it using ore from Boliden's Aitik mine, Sweden. The leach characteristics of gangue minerals, particularly silicate minerals, in heap leaching operations can be of major significance. Umu has now completed the studies on the leaching of a range of silicate minerals in bioleaching chemical environments. A key finding is that fluoride leached from silicate minerals may have an inhibitory effect on acidophiles.

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The RTD activities supported by Rio Tinto have sought to address one of the major challenges that often cause heap leaching operations to fail, namely, methods of construction that impact negatively on fluid flow during heap operation. This has been addressed through a modelling approach to investigate the mechanisms that lead to particle segregation within heaps, allowing methods for the control of this phenomenon at bulk scale to be identified. Another opportunity considered for heap bioleaching technology was the treatment of tailings. However, the need to agglomerate tailings prior to heap leaching raises uncertainties regarding cost. 3.6. Tank bioleaching of flotation tailings and slags The choice of metallurgical wastes, such as tailings and slags, for bioleaching testing was guided by the techno-economic filter developed and reported during year 1 under WP1. Thus, waste resources were chosen that contained metal values which could justify their exploitation or, alternatively, where the possibility of coor parallel-processing of wastes with a hydrometallurgical operation is an option. Preliminary techno-economic studies on Ni-containing tailings from Aguablanca mine gave reasonably encouraging results but it was concluded that a more detailed study using project-specific data would be necessary to confirm this. Although no testwork had been undertaken at this point, after a visit to the RTB-Bor mine and discussions with the mine management, it was concluded that an integrated (bio)hydrometallurgical approach to treating primary concentrates, slag concentrates and tailings from the RTB-Bor mines in Serbia could represent a promising application opportunity. In other studies, the comparative characteristics of a range of metallurgical and industrial oxidic wastes which could be co-processed and/or used as alternative low-cost neutralisation agents in bioleaching processes was established. It was noted that while agglomeration or pelletisation of tailings followed by heap bioleaching is technically feasible, the cost implications will need to be further assessed on a project-specific basis. The alternative approach now being investigated by BRGM is the application of a concept of low duty bioreactor. The target resources under consideration are RTB-Bor copper tailings, Aguablanca Ni tailings and KGHM Cu tailings and low-grade middlings concentrate fraction. Bioleaching amenability has been carried out so far on RTB-Bor tailings and KGHM middlings. The low copper extractions observed for the RTB-Bor tailings using the mesophilic cultures used are related to the poor leachability of the chalcopyrite at the low temperature. Optimisation studies on the KGHM middlings showed a trend of decreasing Cu extraction with increasing feed solids. CIB more recently supplied Mintek with a characterised RTB-Bor Cu concentrate obtained by upgrading of the smelter slag (concentrate currently re-smelted). Bioleach testing on this material showed its ready amenability to bioleaching, and with increased Cu recoveries with increasing process temperature. These results confirm that the co-treatment of the slag with the RTB-Bor Cu concentrates would be an option for an integrated biohydrometallurgical plant at RTB-Bor. The other option being pursued by Seville is the indirect bioleaching of slags. University of Seville are testing a representative range of slag and slag products from reverberatory, electric and flash smelters, including from the Huelva smelter, Spain. Ltu has completed the neutralisation studies of 10 different oxidic byproducts from Swedish industry. Ltu and Boliden are now collaborating to test the use of selected oxidic wastes added as an alternative low-cost neutralisation agent to a refractory gold pyrite– arsenopyrite bioleaching system and the effects of this on bioleaching performance, gold recovery and cyanide consumption. IMN have shown that the total bio-degradation of organics stripped from Pb-bearing slimes was technically feasible to upgrade the slimes.

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3.7. Heap bioleaching of kimberlite ores

4.1. Metal sulfide separation and recovery

Another ongoing related activity has been the biotransformation (accelerated weathering) of diamond-hosting kimberlite ore which may allow the use of less intensive comminution methods. Laboratory results under idealised conditions in the presence of Fe, S and bacteria have clearly demonstrated the potential for biotransformation of the clay components in kimberlite ores (Gericke et al., 2007). Compression tests on treated ore samples clearly demonstrated a direct relationship between the degree of “weathering” and the compression stress measured, although XRD analyses of the mineralogical composition of feed and treated ore particles were shown to be similar.

The blue-sky research in WP3 is the development of beneficiation technology using the properties of bacteria, in particular for the separation of metal sulfides. An open mind is definitely kept to assess whether this know-how is applicable in other fields. The objective is to develop know-how and potential applications for the separation of minerals and metals using the selectivity of the interactions of micro-organisms with surfaces. The following raw materials were chosen for the fundamental research: sphalerite and galena. These minerals are often together mineralised in sulfidic deposits. A first approach that was followed was to use complete microbial cell. One group worked with yeast cells, the other with bacteria. The second approach was to synthesise the particular extracellular polymer that are involved in the attachment process. With the yeast cell, several column flotation tests were done. The pH value, pulp density of the sulfidic particles and biomass concentration were varied. It could be shown by the team of the Technical University of Berlin (Kuyumcu et al., 2007) that due to different surface charges of the several micro-organisms and mineral particles surface attachment occurs (Heterocoagulation = Biocoagulation). A yeast species like Yarrowia lipolytica was suitable. The process is selective. Y. lipolytica acts as collector for galena and sphalerite at different pH values. Flotation tests with the biocoagulates showed acceptable results with averaged recovery up to 90% for single minerals. The yeasts act as collectors for galena and sphalerite at pH-values of about 6 without additional chemicals. Loading densities of approximately one gram sphalerite per 5 to 10 grams yeast were obtained. In research conducted by Ltu (Vilinskaa et al., 2007) where bacterial cells are used, Acidithiobacillus ferrooxidans cells for the surface modification of chalcopyrite and pyrite relevant to the separation of metal sulfides from pyrite has been undertaken. The use of cells adapted to minerals by serial sub-culturing in the presence of minerals is also investigated. The cells exhibited an iso-electric point (iep) at pH 3 while the iep of chalcopyrite and pyrite found to be at pH 6 and 7.5 respectively. The presence of cells shifted the minerals iep close to cells iep, illustrating cells specific interaction with the minerals. The Leptospirillum ferrooxidans cells behaved differently in chalcopyrite–pyrite system than A. ferrooxidans cells where pyrite depressed and chalcopyrite floated with xanthate collector. The differences in the oxidation of mineral surfaces caused by their varied catalytic activity and the production of OH⁎ radical besides bacterial oxidation of the surfaces played a significant role for xanthate adsorption and flotation responses of the minerals. A second approach that is followed by UDE is not to work with complete organisms, but to try to extract and synthesise the EPS that is thought to be responsible for the selective binding to the metal sulfides. Experiments to stimulate EPS production by adding quorum sensing active agents have been started. Preliminary results indicate that two compound groups can be distinguished showing either a negative or a positive effect on attachment. So far, only the system pyrite with A. ferrooxidans ATCC 23270 has been investigated. Elucidation of EPS biosyntheses genes and regulation by the microarray technique (in cooperation with CNRS) in the systems pyrite with either A. ferrooxidans ATCC 23270 or strain A2 has been started.

3.8. General research activities Significant RTD effort by a number of partners during years 1 and 2 had gone into bio-prospecting and as a result a microbial culture register was created to support needs arising from bioleaching research on the various identified target resources and for other research purposes. Over this period, it was also recognised that the bio-prospecting activities were intimately inter-related with the microbial consortia and biomolecular tools activities. The major technology advance arising from these combined studies was the provision of a range of tools to more rigorously define and monitor the mesophilic and moderately thermophilic consortia that exist in bioleaching systems. In view of the emerging importance of thermophilic bioleaching processes, it was considered important to now extend these capabilities to include the thermophilic processes. A notable advance was the isolation of psychrotolerant acidophiles, which may have previously unrecognised importance for the start-up of heap bioleaching processes in cold conditions (Dopson et al., 2007). Other key advances were studies using “constructed” consortia of four key types of mesophilic micro-organisms found in the tank bioleaching systems. This work has begun to provide improved understanding of the consortia dynamics for the bioleaching of a number of the target concentrate resources. Ongoing studies have also addressed the role of extracellular polysaccharides in cell-mineral attachment and their relation to bioleaching performance (Harneit and Sand, 2007). An important advance regarding an improved understanding of the molecular biology (genetics, transcriptomics and proteomics) has been promising research results on functional gene probes which may enable the detection of key specific activities in thermophiles, such as iron and sulfur oxidation, to be monitored during bioleaching. Related ongoing research was the use of a transcriptomics approach to investigate the expression of iron and sulfur oxidation pathways in mesophilic bioleaching species (Bruscella et al., 2007). Steady progress was also made in developing genetic systems for the important bioleaching micro-organisms, with specific focus on achieving an improved understanding of the metals resistance mechanisms. This is state-of-the-art research and there are no other known research groups carrying out similar work. 4. Metal separation and recovery from solids and liquids A major driver for the work on bioleaching (WP2) is to reduce the environmental impact of the mineral industry. However, that cannot be completely prevented. The aim of the work package 3 of BioMinE is to develop technologies that can tackle environmental issues that remain despite these efforts. The technologies (like treatment or polishing of the final effluents) should fill the gaps or interact with existing treatment technologies to ensure that the overall metal extraction process is environmentally benign. But, WP3 goes further than just a developing treatment technique. The aim is also to integrate treatment and metal recovery. This can be especially attractive for metal of secondary importance in concentrates; metals that are often wasted to the tailings dam.

4.2. Dissolved metal recovery from bioleachates This exploitable result and the cluster around are focused on three possible applications: 1) Recovery of metals secondary metals from bioleach stream (or other leached streams like autoclave). ‘Secondary metals’ are for

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example nickel from a Cu/Ni concentrate or copper and zinc from a gold leaching operation. 2) Recovery of metals from wastes and tailings treatment. The technoeconomical filter that was developed and applied in the first year of BioMinE indicated that the wastes and tailings represent a massive resource in Europe. In WP2 the focus is on dissolving these metals with low-cost and low-intensity bioreactors. A SX-EW metal recovery system will be uneconomic when such technology is applied on a small scale or with low intensity. An economic alternative is to produce a pure intermediate product (a sulfide or carbonate) that can be sold as a high-value concentrate to a smelter or a hydrometallurgical plant. 3) Recovery of metals from naturally leached streams. A large opportunity actually exists to recover metals from run-offs from old mines, tailings etc. This so-called acid mine/rock drainage can contain metal concentration of up to 1000 mg/l copper at flows of a dozen to several 100 m3/h. However, the Cu load is often too small for a conventional SX-EW so the stream is at best neutralised and the metals are wasted to the tailings dam. A biologically driven metal recovery can recover these metals at an attractive price. So, acid mine drainage with a relatively high metal contents (i.e. 500 mg/l of copper) could be turned into a resource or asset instead of being a problem. The objective for this exploitable result is to collect technology that can economically and efficiently recover valuable metals of medium concentration from aqueous streams. The work under this “exploitable result” is directed both to the abiotic precipitation of metals (for example nickel precipitation from Cu/Ni tank leach after Cu SX-EW) and to the (selective) precipitation of metals inside a bioreactor with sulfidogenic biomass. Both rely on the same principles with regard to the metals because the selective recovery of metals from either bioleaching or waste streams can be achieved through exploitation of the different solubilities of various metal sulfides, e.g. the Ksp Cu bb Zn b Fe. The major control parameter is the pH. In off-line systems, several precipitation stages can be operated at different pHs that are all fed with either gaseous or dissolved sulfide. Key to commercial and/or large-scale deployment of such a technology is the development of systems with better process control e.g. ability to achieve selective precipitation from mixed metal solutions. Acidophilic sulfate-reducing bacteria (aSRB) have been targeted as interesting agents for use in such selective metal recovery systems. One important objective of the project was to increase the understanding of the physiology of these microbes, relative to their potential metal precipitation. The practical work in BioMinE with acidophilic sulfate-reducing bacteria (aSRB) showed that recovery of Zn from a Zn and Fe containing solution was successful in a bench-scale system. The bacteria isolated in the bioreactor were identified as Desulfosporosinus sp. that grew better at pH 5 than at pH 6, indicating that they are acidophiles. However, the conversion of the electron donor glycerol is incomplete and the by-product acetate becomes easily toxic at the low pH of the experiment. It is almost certain that a second organism is present that converts the acetate. Novel strains of aSRB have previously been isolated by UWB from a mine site in southern Spain. Phylogenetic analysis indicated that these are distinct from the Desulfosporosinus sp. isolate M1 that have been tested under lower pHs. Growth was seen on plates at a pH as low as 2.5. The aSRB cultures were further assessed for their use of various organic electron donors using a 96-well plate assay. A variety of compounds was tested with the mixed culture to see if they could support sulfate reduction by the co-culture. These included a variety of sugars that Acidocella PFBC can use for growth aerobically (but not anaerobically) such as fructose and sucrose, as well as some aromatic compounds including benzoate and phenol. In addition, other compounds that did not support growth of either micro-organism

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were tested, including sugars such a glucose and galactose, as well as methanol. In no case, however, was sulfate reduction apparent, indicating that the syntrophic partnership was limited by the provision of acetate to Acidocella PFBC by the aSRB, and that only acetate can be catabolised by PFBC in the absence of oxygen. It appears that selective metal recovery systems based on these aSRB are limited to a small range of potential electron donors, notably only those that can be used by the aSRB. Previously it was shown that two different aSRB isolates (M1 and PFB) were capable of using the same range of electron donors, including glycerol, ethanol, mannitol, fumarate, citrate, succinate, glutamate, propionate and yeast extract. Isolate PFB was also able to reduce sulfate, using malate as electron donor. Previous work also identified that the two aSRB produce acetate from organic electron donors, which can inhibit aSRB at low pH. However, in consortium consisting of the aSRB and a second heterotrophic acidophile (Acidocella PFBC), no acetate was detected due to syntrophic interactions between the two acidophiles. Paques and WU worked on acidophilic or acido-tolerant sulfatereducing bacteria with H2 as electron donor and CO2 as carbon source. Here, the aim is to precipitate nickel selectively from a stream containing iron and nickel. First, a test was run at pH 6 to separate zinc and iron. That proved feasible. Then, the same was done for nickel and iron. The results were also promising although the system was slightly less stable. Both the nickel and zinc sulfide could be removed from the bioreactor effluent by settling. An investigation was also done in the toxicity of sulfide at a pH of 5 in a gas-lift reactor. The removal of sulfate became incomplete at a sulfide concentration of N500 mg/l. The population in these bioreactors has also been studied. Considerable progress has been achieved with the molecular phylogeny of the pH 5 (16S rRNA), pH 4.5 (16S rRNA and dsrB), and low and high sulfate-reducing bioreactors (16S rRNA) are now completed. An experimental set-up has been operated for biological sulfur reduction for those systems where the metal is precipitated in a separate compartment (contactor) from the bioreactor. The process could be further improved. An H2S concentration of N15% in the rich gas to the contactor could be achieved and this could be maintained. The sulfide precipitation was also tested for nickel. Good recovery rates (N99%) from a 5 g/l solution could be obtained at a pH b 5. 4.3. Water purification, recovery and reuse The metal and mining industry is well known (and criticised) for its large impact on local water conditions in the widest sense. Effects on groundwater levels, consumption of water for processing plant, acid mine drainage and the release of water with a quality that is often insufficient to allow reuse, are the main issues. Developed technologies are aimed at improving the quality of discharge for a variety of applications and particularly the effluents of bioleaching operations. They are focussed on the use of biological processes but also take interactions with other processes like membrane technology also into account. As a first step, as much as possible of valuable metals should be recovered. Then, the water should be processed to remove remaining metals and salts. The aim is to process water to a level that is suited for the envisioned reuse. The objective of this exploitable result is to collect technology to purify water for different types of reuse, with biotechnological processes as a core component. The microbial population in fluidised bed reactors that were primarily aimed to remove sulfate from water has been investigated. The water that is released from bioleaching operations is often of a high temperature. A biological sulfate removal/sulfide generation at high temperature is beneficial when processes are coupled. Work has primarily been done on both thermophillic (65 °C) and psychrophillic (9 °C) organisms. The electron donor of a fluidised bed

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Fig. 4. Treatment flowsheet devised by Imperial College using filtration and reverse osmosis for recycling water in the process of bioleaching of refractory gold concentrates.

reactor (FBR) was switched from ethanol to formic acid to test whether the volumetric activity could be increased. This proved indeed the case as the activity increased two-fold to a maximum 850 mg/l/d rate of sulfate, although after a long lag period. The population was studied with PCR-DGGE (Polymerase Chain ReactionDenaturing gradient gel electrophoresis). The population was still surprisingly diverse despite the high temperature. A second new thermophillic SRB genus was described: Desulfurispora thermophila gen. nov., sp. nov. and deposited into public databases (Deutsche Sammlung für Mikroorganismen, DSM and Japan Collection of Microorganisms, JCM). Additionally a manuscript on the description of another new sulfate-reducing species, Desulfotomaculum alcoholovorum, sp. nov., was submitted. The increase in activity upon a change of ethanol to formiate was more pronounced under psychrophillic conditions; an increase from 0.4 to 1.4 g/l/d of SO4 conversion was observed at a residence time of approximately 20 h. The conversion of sulfate was not always stable as it fluctuated between 50 and 90%. The reactor operation could be stabilised by applying a slightly higher influent pH from 3 to 4.5 and by lowering the free sulfide concentration through precipitation. A PCR-DGGE analysis indicated that all bacteria present in this culture had a resemblance with previously known bacteria of 98% or more. The picture in Fig. 4 shows in a simple way imagined by Imperial's team how membrane technology can be introduced into a bioleaching flowsheet to upgrade the water quality. The work on membrane technology with synthetic liquors, based on data from an industrial process, were subjected to filtration, reverse osmosis and/or resin ion exchange processes under designed conditions in a re-circulating system. Arsenical ferrihydrite precipitated from the synthetic liquors with lime retained most of the arsenic(V) (As b 100 ppb). Over 90% of residual As(V) was removed by reverse osmosis thus achieving the WHO standard (As b 50 ppb for discharge). Drinking water standards were readily achieved by reverse osmosis and ion exchange employed in sequence. Arsenic(III) was poorly retained by the RO membrane

(only 20–55% removal) because arsenite existed as neutral molecule (which readily penetrated the membrane). Therefore prior oxidation of As(III) to As(V) is a pre-requisite. The ecotoxicological assessment (Algaltoxkit) that was used in the beginning of the project by Umicore proved also useful in this research although the analyses were time consuming and required experience with algal cultures. The algae became insensitive to arsenic below 100 ppb. With regard to the removal of heavy metals, synthetic mine liquor was spiked with high concentration of Cu, Ni, Zn, Cd (1 g/l) and Pb, Hg (0.5 g/l). The percentage of heavy metal removal with neutralisation and precipitation was approximately 98–99% for Cu, Pb and Hg, but less for Ni, Zn and Cd. Reverse osmosis achieved more than 90% removal of Cu, Ni, Zn and Cd but very poor removal of (un-ionised) Hg. Concerning waste from cyanidation, cyanide residues (typically 2 g/l and 0.18 g/L for 35 and 70 °C bioleach) could be destroyed (e.g., by hydrogen peroxide); complexed (e.g. with iron salts); or recycled. Preparation of Prussian blue with iron from bioleaching was successful in the laboratory at initial low pH but the complex did not survive neutralisation. This work is also useful for effluent polishing. 4.4. Effluent polishing The demands on the quality of the final effluent of industries, including metal and mining, are becoming more strict as the European Water Directive is coming into force. The way the water quality is determined is also likely to change. Currently the quality is basically determined based on concentrations of compounds. However, ecotoxicity tests, which determine the quality of an effluent with a test on organisms like bacteria, algae, fish, etc., are expected to be required. Furthermore, the type, quantity and quality of the receiving water will be taken into account. The experimental work in the first year of BioMinE showed that a biological treatment resulted in less ecotoxicity than a physicochemical treatment. However, metals like arsenic, selenium, thallium

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etc. that are noxious at low concentrations receive more attention as problematic metals in final effluents. Experiments of sulfate reduction carried out by BRGM on acidic influent as high as 100 mg/l of As have shown the capacity of efficiently removing arsenic down to 1 mg/l. Molecular biology analyses were performed at different levels inside the fixed film bioreactor. Liquid samples were considered as representative of the biofilm colonizing the column. Biodiversity studies (16S rRNA gene for phylogenetic identification and arrA gene for arsenate reductase detection) were focused on the biofilm from the middle of the column. Analysis of 16S rRNA gene sequences revealed a diverse population composed of at least of 4 Gram+ genera. A new Desulfosporosinus strain (96% id. with Dsp. orientis) was selected in the column. Only one arrA sequence, related to Desulfosporosinus arrA sequence, was detected. Those results suggest that the new SRB is the only one responsible for As(V) reduction in the process. In the glycerol-fed bioreactor, the Desulfosporosinus ratio was important at the bioreactor bottom, near the feeding point, and decreased from this point to the outlet. This result is consistent with the sulfate reduction occurring in the first one third of the column, where the energetic substrate glycerol is available. Feeding with H2 increased the ratio of Desulfosporosinus and Sporomusa-like bacteria along the column, probably because H2 (energetic substrate for SRB) is uniformly distributed in the bioreactor. On another hand, a new sulfate-reducer was isolated from the bioreactor. Species description including determination of optimum pH, ability to use As(V) as terminal electron acceptor, substrates utilization, etc. is ongoing. NTUA's work is focussed on base metal removal from effluent of metallurgical processing (Kousi et al., 2007) with the main following objectives: • Residence time optimisation for both nutrient and waste stream, • Efficiency optimisation of the reactors in terms of metal removal for both synthetic and real wastewater. The solid phase inside the bioreactors was more closely investigated. Both XRD and SEM-EDX analyses show that metals like zinc and iron had precipitated as fine amorphous sulfides. This had as a drawback that bacterial cells become encapsulated by zinc and iron sulfides as observed by SEM-EDX. However, this did not appear to affect the bioreactor column performance. This is explained by the fact that the bacteria are continuously growing, thereby created new surface area for exchange of products and nutrients. 5. Studies of the integrated process flowsheets (WP4) This is during the third year of the project that the activity in the workpackage 4 has started being significant with the determination of

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the specifications of the operating conditions and of the equipment of the applications that include a processing step with the use of the bioleach technologies to be techno-economically evaluated. A focus on indirect bioleaching of zinc/lead bulk and polymetallic concentrates has demonstrated very attractive results and the combination of expertise in WP2 on microbial aspects and in WP4 on the process side have had a synergetic effect on the development studies. Work on the optimisation of the metal recovery from the pregnant solutions (Zn/Cu/Ni) or from the solid residues (Pb/Ag) according to the resources treated has progressed towards a reliable knowledge of the performances of the technologies used. The exploitation of the data obtained at bench-scale has allowed establishing the design of process flowsheets from the attack of the mineral resources by bioleaching to the recovery of pure metals and water recycling. The time schedule of this workpackage aiming at the demonstration operations during the fourth year of the project is quite respectful of the planning as shown in Fig. 5. 6. Training and dissemination of knowledge The work of design and implementation of learning objects on the web covered by the workpackage 6 has now a close and direct contact with the R&D activities, since this work has been fully accepted among the partners and is used by them. Many other partners than WP6 partners are now contributing to the work as extra services. This is especially true for the BioMineWiki (http://wiki.biomine.skelleftea.se/ wiki), which was launched during the spring of 2007. The wiki is on good way to develop into a ‘living’ instrument, a network community tool and a reference tool to be presented as a service for people starting a professional career in biohydrometallurgy. The wiki is expected to play a vital role in the dissemination and exploitation work also. 7. Economy and sustainability The study of the macro-economy of the markets of copper and zinc, which are the two main metals targeted in the project in the European perspective, have shown that the demand of those metals is so high that local mine-to-metal installations using biotechnological processes are particularly attractive, even if the viability of the implementation of such installations is site specific. Europe does have a lot of existing refining capacities and some are to be upgraded. Biotechnologies could be considered here not to replace the refining process but to overcome some problematic steps of the existing capacities. The successful development of a bioleaching route would enable existing facilities to expand their output without installing

Fig. 5. Time schedule from amenability test work to pilot-scale operations in the frame of BioMinE.

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Acknowledgements The mining owners and operators that have provided samples of the benchmark materials tested in the frame of the BioMinE are gratefully acknowledged as well as for the relevant information to their resources. These are Rio Narcea (Spain), Boliden (Sweden), RTBBor Grupa Mine (Serbia), KGHM (Poland) and Somincor (Portugal). This paper is a contribution to the coordination activities of the BioMinE project co-financed by the European Commission (through a contract under the reference NMP2-CT-2005-500329). References

Fig. 6. Conceptual cost comparison for base metal production route alternatives.

additional roasters. A further advantage would be the ability to accept a broader range of concentrates, including those unsuitable for roasting for example, those with high copper levels in the case of zinc concentrate for instance. After screening all the processing routes for extracting zinc from sulfide concentrate, it appears that the mine-to-metal route could be competitive depending on Treatment Charges/Refining Charge's forecasts and cost estimates. One should bare in mind that better recoveries can probably be obtained with a more basic concentration step in the mine-to-metal route than in the traditional one (see Fig. 5). This may be not only a way to raise the yield of recovery of metals from the mineral resources and to increase the diversity of the resources, but also to improve the sustainability of the whole process chain of production of metals from primary or secondary materials (Fig. 6). This will be during the fourth year of the project and while obtaining the results of techno-economic evaluation of the selected processes that the sustainability of the different routes will be assessed by USTUTT and PE International in comparison with conventional ways of recovering metals. 8. Conclusion While the market pull becomes more and more visible on a longterm basis with the high price levels of the non-ferrous metals, the technology push as developed in BioMinE is more and more selfassured and ready to match the needs. At the end of the first year, the objective of having selected benchmark resources was reached. Within the second year, the technologies for treating the typical European resources selected were established. The third year was particularly dedicated to achieving most part of the amenability testing and defining through bench-scale studies the operating conditions for pilot-scale demonstration operations to be mainly undertaken during the last year of the project. This is also during this last year of the project that the screening of the exploitable results has given more opportunity to the partners to focus their involvement and their efforts on subjects that represent a true European challenge. The clusters of partners around a limited number of exploitable results targeting real evaluation of processing routes have allowed rationalizing the work and reinforcing the motivation about the success in terms of applicability of the process developed.

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