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MINTEK ANNUAL REPORT – 2008

"Mintek has been granted Medium-Term Expenditure

Framework (MTEF) funding by the

Treasury, over three years, specifically

for uranium-related work, and is exploring a possible link with a Uranium Centre of Excellence in conjunction with

the DST. "


GolD InDUSTry

AuTEK – developing new industrial applications for gold

Project AuTEK, the joint R&D initiative between Mintek and the three major South African gold producers to extend the industrial uses for gold, has been running for nine years. The project has three main areas, in the fields of catalysis, nanotechnology, and biomedical applications.

Biomedical programme

The AuTEK Biomedical programme, which is co-funded by Harmony Gold, focuses on the discovery of new types of gold-based biomedical agents with the emphasis on HIV/AIDS, cancer, and malaria. In 2007, a strategic decision was taken to focus the in-house research effort on HIV, with both the cancer and malaria research programmes continuing at the universities, although still directed by Mintek. Promising results emanating from the universities will be brought in-house and developed further through various established networks.

Research under the HIV programme is aimed at increasing the in-house knowledge base, focusing on gold-based drugs and the HIV integrase enzyme.

Novel synthetic compounds submitted by consortium members and collaborators in the programme are screened theoretically and evaluated experimentally for cytotoxicity, anti-viral activity and solubility, while focused research projects take place in-house. Progress in both the screening and the research legs continues to be made within expected time-frames, and two series of potential anti-HIV compounds have been identified that warrant further investigation.

Over the past two years in the cancer programme, AuTEK Biomed has actively pursued the development of a "hit" series of compounds (active and selective). Primary progress includes the filing of a South African provisional patent covering a family of metal-based

Research, Development & Technology

Dr Molefi Motuku,GM: Research and

Development.

anti-cancer compounds, and the submission of five series

of samples to partners in the USA for further development.

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Top left: The THRIP-funded NMR Spectrometer, used to analyse the structures of new compounds developed in the AuTEK biomedical programme.

Middle: Screening platform for HIV, malaria, and TB to support the South

African research community.

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the potential for funding to set up the proposed central in vitro screening facility.

One of AuTEK Biomed’s key competitive edges includes the ability to not only screen compounds within their intended discipline but to extend the screening to a "shotgun" approach within other areas. More than fifty compounds prepared within the malaria research programme are currently being screened for anti-cancer and anti-HIV properties.

The close of 2007 saw the graduation of a number of long-term bursars and the incorporation of some into other aspects of the AuTEK Biomed program. Since commencement, AuTEK Biomed has seen the graduation of four PhD and six MSc candidates, with a further four PhD and three MSc graduations expected mid-2008.

In an effort to comply with international standards, AuTEK Biomed has spent the past year establishing the necessary procedures and documentation for Good Laboratory Practices (GLP), and is now undertaking the final steps towards implementation and the application of quality standards to the biomedical facility. A pre-assessment is planned for mid-2008.

Although most of the malaria research activities are now university-based, Mintek continues to play a role though its position on the South African Malaria Initiative (SAMI) steering committee.

"Gold catalysts are unique in terms

of their ability to catalyse oxidation

reactions at low temperature and/by the use of molecular

oxygen."

Dr Roger Paul,GM: Technology.


Recent SAMI endeavours include the Lifelab in vitro screening platform for HIV, malaria, and TB to support the South African research community. Mintek led the HIV leg of the pre-proposal, as well as championing the process. Though initial approaches to appropriate

funding mechanisms were unsuccessful, efforts are continuing to investigate

Left: Purification of nanoparticles using size exclusion chromatography (SEC).


Mintek’s on-site facilities were expanded with the commissioning of a Bruker 400 MHz AVANCE III NMR Spectrometer, which was purchased with AuTEK THRIP funding. This instrument is not only an indispensable analytical tool, but will also be used in various other aspects of Biomed’s drug discovery endeavours.

The Department of Science and Technology (DST) has set up the Technology Innovation Agency (TIA) to incorporate various existing funding institutions. This will involve a fair amount of restructuring, and the establishment of a number of centres of competence. In line with its decision to focus on HIV in-house, Mintek is in discussions with the DST with a view to participate in the anticipated HIV Competence Centre.

Representatives from AuTEK Biomed participated in the European Collaboration Network COST D39 Action workshop on metal-based drug design and action in Lausanne, Switzerland, as well as in various local conferences and workshops. 2008 will see the attendance of international meetings that include the 4th International Symposium on Bio-organometallic Chemistry (ISBOMS’08) and Aids ’08, both in the USA.

Nanotechnology

The Mintek/DST Nanotechnology Innovation Centre (NIC), an initiative of the Department of Science and Technology, was launched in November 2007. The centre will receive R50 million over the next three years to research mineral-based technologies for use in health (sensors and biolabelling) and water nanotechnology applications.

Activities in the nanominerals

and sensor platforms are under way, with three main categories of products – monolayer protected clusters (MPCs), biconjugates, and colloids – ready for trialling. Mintek has supplied samples of various types to other research institutions, and sold a batch of gold nanoparticles to an industrial client to test the effect of adding precious-metal nanoparticles to their industrial processes. Preliminary discussions have been held with several UK-based nano-industries for the supply of material, and it is expected that definitive agreements could be reached in mid-2008. The value addition to these materials through processing at Mintek is about a hundred-fold.

The production of citrate-stabilised gold nanoparticles for biolabelling has been scaled up to the 20 litre stage, demonstrating that commercial quantities of nanoparticles can be successfully synthesised.

Two MSc projects are under way at Rhodes University, and a PhD at the University of Free State, on the

biosynthesis of platinum and gold nanoparticles respectively, with the aim of elucidating how biochemical mechanisms influence particle size and shape.

In electrochemistry, the focus has been on building up infrastructure for testing sensors. Work will start in the second quarter of 2008 on the prototyping of lateral flow tests for point-of-care diagnostic (screening) applications in rural areas.

The consortium agreement between the various stakeholders of the NIC – the DST, Mintek, the Water Research Commission, the Medical Research Council, and the

Middle right: Prototype lateral flow sensor using gold nanoparticles.

Bottom right: High-resolution scanning electron microscope in the

nanotechnology laboratory.

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universities of Johannesburg, the Western Cape, and Rhodes, was signed in March 2008. University funding was available from the beginning of the academic year, and the NIC is currently supporting about 30 bursars from Honours up to post-Doctoral levels.

A particular highlight of the NIC has been the establishment of a nano-minerals programme in South Africa that includes clays, metals, and metal oxides as well as precious metals, and which approaches nanotechnology from a metallurgical/minerals science viewpoint rather than from the more commonly-used chemical science perspective.

Research under the AuTEK nanotechnology programme is co-funded by Gold Fields.

Catalysis

Gold catalysts are unique in terms of their ability to catalyse oxidation reactions at low temperature and/or by the use of molecular oxygen. Examples of such reactions include:

• CO oxidation – e.g. gas masks, air purification;

• Oxidation or selective oxidation of organics – e.g. glucose to

gluconic acid, cyclohexane to nylon precursors;

• Epoxidation – e.g. propene – propene oxide (a plastics precursor);

• Mercury removal from coal power plant emissions; and,

• Hydrodechlorination (destruction) of groundwater pollutants such as trichloro-ethene.

The widespread industrial use of gold catalysts in such applications could result in a large offtake of gold, and furthermore would add to the range of precious-metal beneficiation initiatives in South Africa.

Novel gold catalysts produced by the AuTEK Catalysis group are marketed to potential end-users under the name AUROliteTM, in conjunction with the World Gold Council (WGC). The AUROliteTM range includes powdered or shape-formed gold materials based on TiO2, Al2O3, and ZnO supports.

Mintek has seen a drastic upswing in demand for its gold catalysts since the start of 2008, with particularly interest from end-users in the field of CO oxidation.

This is regarded as a payoff to its marketing efforts with the WGC, and justifies the further scale-up of the production process from the current 15 kg level to 65 kg batches.

The AuTEK Catalysis programme is co-sponsored by AngloGold Ashanti.

Cyanide Services

Mintek has been involved in cyanide-related research and routine work for over 25 years, and has built a solid foundation in soil, solution, and gas-phase analysis and mass-balancing of cyanide. The Cyanide Centre is an industry-focused hub that aims to assist in minimising risks associated with cyanide use, increase general knowledge on all cyanide-related issues, and provide management tools to reduce the gap between legislative requirements and actual cyanide levels attained.

The Cyanide Services laboratory has been certified by SANAS, the South African National Accreditation Services, as meeting the requirements of ISO 17025 (Testing and Calibration Laboratories). The specific scope of the certification is for water-quality evaluation by determination of total cyanide and weak acid dissociable (WAD) cyanide, using continuous flow analysis (SANAS/ISO 14403), for process and environmental samples. With environmental criteria and process controls in the gold industry becoming more sophisticated, the need for data provided by independently certified laboratories has increased significantly.

During the period under review, a pre-operational site-assessment audit was undertaken for a development-stage gold project in Malaysia. A plant and environmental forensic audit (for both cyanide and arsenic) was

Top left: Assembly of prototype lateral flow sensors.

Middle: Underground visit to monitor cyanide levels in backfill.

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Left: ISO 17025 audit of the Cyanide Services laboratory.


carried out at the Obuasi mine in Ghana, and cyanide destruction testwork conducted for several gold projects in West Africa and locally. Mintek has also been commissioned by Gold Fields to monitor all surface discharges and groundwater borehole samples on their mines in the West Wits area.

Mintek contributed its intensive knowledge of the environmental fate of cyanide to a collaborative project with AngoGold Ashanti and the zoology department of North-West University, which investigated the behaviour of birds using the tailings environment as a habitat. The project has resulted in a better understanding of the effectiveness of current management practices in protecting birds from cyanide, as well as indicating where certain improvements could be made.

Metallurgical process work

Laboratory-scale gravity concentration and leach optimisation tests were conducted on four composite drill-core samples from Etruscan Resources’ Agbaou gold project in Côte d’Ivoire. The results were incorporated in the ongoing feasibility study, which is being prepared under the supervision of MDM Engineering and Coffey Mining. Previously, Mintek did similar work for Etruscan’s Youga project in Burkina Faso, which began production at the beginning of March 2008.

Confirmatory testwork was done on samples from the Lily gold mine (Eastern Goldfields) via MDM Engineering. A bankable feasibility study for the underground development was completed in March 2008 by Turgis Consulting.

A major programme of testwork for BASF South Africa examined the effect of wetting agents on the dissolution of gold during heap leaching of ores from West Africa and the USA. This work is being extended to the effect of the agents on carbon regeneration.

Top right: A bench-scale centrigual concentrator used to recover coarse

free gold particles prior to leaching.

Middle: A typical screen-printed electrode used in electrochemical

studies.

Routine weekly leach tests were conducted for Grinaker-LTA to monitor the performance of the Segala gold plant in Mali. This project has been ongoing for several years.

Extensive testwork was conducted to optimise the process parameters for IAMGOLD’s Mupane gold mine in Botswana and AngloGold Ashanti’s Navachab mine in Namibia. Other work included scoping studies to select processing routes for projects in South Africa and Latin America, confirmatory leach tests for Kalgold (Harmony Gold Mining), and an investigation of the effect of osmiridium (a naturally occurring alloy of osmium and iridium) on the gold leach process for Knelson Concentrators. Process testwork was begun as part of the pre-feasibility study on the Monarch gold deposit in Mozambique for Sephaku Holdings (African Process Minerals).

PlaTInUM-GroUP METalS (PGM) InDUSTryConRoast process development

A continuous smelting campaign to recover PGMs from revert tailings and high-chromium concentrates for Braemore Platinum, utilising

Mintek’s DC arc-based ConRoast technology, started at the end of September 2007. In the six months to end March 2008, a total of more than 5 600 t of material were processed at feed rates of more than 1 000 tons per month. PGM recoveries consistently exceeded 99 per cent, even when smelting selected lower-grade revert tailings. The sulphur dioxide (SO2) emissions were negligible, registering below three parts per million (ppm).

The ConRoast technology is able to recover PGMs from concentrates and other materials that contain high levels of chromium and low sulphur, which are metallurgically challenging for conventional "six-in-line" smelters. Most of the development-stage PGM projects in South Africa would produce concentrates with higher chromium and/or nickel contents. Moreover, the established smelters are running at, or near to, capacity. Braemore, in conjunction with TWP Consulting, is finalising a feasibility study for a new 10 MW ConRoast smelting facility on the western limb of the Bushveld Complex to treat concentrates from emerging and established PGM producers.

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Right: Cyanide destruction testwork.


Commissioning is planned for 2010, and this could be followed by a larger facility of about 40 MW incorporating a base metal refinery, on the eastern limb.

Various unit process options in the ConRoast flowsheet have been extensively tested in Mintek’s facilities, as well as those of leading global specialist engineering companies. The dead-roasting step has been tested by major fluidised-bed vendors in pilot plants in North America and Europe, and water atomisation of the alloy from the DC arc furnace has been conducted by the leading supplier of atomisation technology in the UK. Small-scale roasting and smelting tests on a range of PGM concentrates have been completed, and converting tests of the product alloy have started at small-scale.

Batch pressure-leaching testwork on samples of the atomised PGM-bearing alloy is being conducted in conjunction with Hydromet (Pty) Ltd in Springs. This will extend to piloting, incorporating both leaching and downstream recovery steps, at Mintek in the second half of

2008. The flowsheet consists of pressure leaching, iron removal, recovery of nickel and cobalt as a mixed hydroxide, and copper electrowinning. The PGMs remain in the residue from copper leaching, which will be a suitable feed to a precious-metals refinery.

In mid-2008, the demonstration smelting facility will be upgraded to double its capacity to 2 000 t/month. This will involve installing a 4 m diameter DC arc furnace, a flash dryer to replace the current rotary kiln, and modifications to the power supply and gas cleaning plant.

Process development and optimisation

Bench-scale comminution and flotation work were done on core samples from Wesizwe Platinum’s Frischgewaagd-Ledig project in the Pilanesberg area, with the emphasis on ore variability. Wesizwe gave the go-ahead for the project in March 2008, after completing a positive bankable feasibility study. Similar work was undertaken for the adjacent Ngonyama project (Area 1 of the

Western Bushveld Joint Venture between Platinum Group Metals Ltd, Anglo Platinum, and Wesizwe), as input to the feasibility study headed by Turnberry Projects.

The final phases of testwork were completed in support of the feasibility study for Barrick Gold’s Sedibelo project, which was extensively piloted the previous year (Annual Report 2007).

Other projects included ore characterisation to assist in the design of mill liners for Platinum Australia’s Smokey Hills project, and bench-scale flotation work on core samples from M’Phatlele (Platmin Ltd). An evaluation of gangue depressants for possible use in the flotation circuit at the potential Blue Ridge West UG2 plant was carried out for Senmin.

There was a consistently high demand for mineralogical service work to characterise PGM flotation products during plant design, optimisation, and troubleshooting projects. Two of the top QEMSCAN experts from Intellection in Australia visited Mintek for a week-long exercise in evaluating and upgrading the facilities for quantitative PGM mineralogy.

In conjunction with the University of the Free State, Mintek has entered into the Inkaba yeAfrica programme of earth science collaboration between South Africa and Germany, which will form a basis for mineralogically-oriented PGM R&D. In 2008, research will focus on the automated identification of PGMs at high resolutions (less than 5 μm), which is a somewhat contentious issue. Another area of activity will consider the applicability of base-metal sulphide minerals as proxies for determining the behaviour of PGMs in recovery processes.

Mintek has commissioned a

Top left: The 80-ton uniaxial compression press for powder-metallurgy work.

Middle: Tapping PGM-bearing alloy from the DC furnace.

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Left: Ingot of PGM-bearing iron alloy.


second high pressure grinding roll (HPGR) to complement the Polysius unit that was installed in 2006. The new machine, supplied by Koppern, has a 1 m diameter roll and a nominal throughput of up to 50 tons per hour, which is sufficiently large for the results to be scaled up directly from pilot work to full scale. Together, the two units enable Mintek to undertake HPGR work on any material at various scales. Testwork to date, mainly on various PGM ores, has indicated that the results are very orebody-specific, but that energy savings of more than 20 per cent are possible in grinding to 300 μm size. An extensive R&D programme has been planned, which will address two key areas – energy reduction compared with conventional crushing/SAG/ball milling circuits, and the effect on downstream processes such as flotation and leaching. In the course of the past year, Mintek has gained a lot of experience relating to HPGR technology and its appropriateness for various PGM, gold, uranium, and base-metal ores, and can offer the only independent facility in South Africa for conducting pilot-scale testwork to produce high-quality data suitable for feasibility studies.

Advanced materials incorporating PGMs

As part of the development of the thermodynamic database for the Pt-Al-Cr-Ru system, the phase diagram work has been completed on the Pt-Al-Cr system. This enables the optimisation of the Pt-Al-Cr model against the available experimental data. The Al-Cr-Ru model has also been completed. Both these systems were calculated in collaboration with Dr A. Watson of Leeds University. The two models were combined with those of

systems completed earlier – Pt-Al-Ru and Pt-Cr-Ru – to establish a database for Pt-Al-Cr-Ru. With this database, phase equilibria from 600ºC up to the liquidus temperature can be predicted reasonably well, and it can thus be a valuable tool if the alloy system were to be commercialised in an application for high temperature and/or corrosive environments.

An 80 t uniaxial compression press, built entirely in South Africa and funded by the DST under the Advanced Metals Initiative, was commissioned for research in powder metallurgy. The unit will be used mainly to produce metallic powder components, although it is also able to handle ceramic materials. The press can be operated in conjunction with a water atomiser that produces metallic powder feedstock down to a size of 20-100 μm from materials with melting points up to 2000°C. Although installed specifically to handle platinum-based alloys, the atomiser is being used for a range of metals, including ferrous alloys. These two items of equipment, which constitute the first R&D

facility in South Africa combining water atomisation and uniaxial compaction, are being used to investigate the influence of powder properties such as particle size, flowability, and compressibility on the strength and density of powder metallurgy components.

Powder metallurgy is used to manufacture small, high-precision components that do not require machining to finish them. Mintek is investigating in particular the application of the technique to platinum-based superalloy components, which are difficult to fabricate in bulk form. Currently, standard specimens can be manufactured and tested to Metal Powder Industries Federation (MPIF) specifications.

A simultaneous thermal analyser, partially funded by the NRF under the National Equipment Programme, has been commissioned for high-temperature differential thermal analysis and thermogravimetry of metallic materials. The instrument, which is one of only a few in the southern hemisphere, is equipped with a tungsten

furnace capable of temperatures

Top left: The water atomiser handles materials with melting points up to

2000oC.

Middle: The Knoppern high-pressure grinding roll (HPGR).

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Right: The wear-resistant roll surface of the Knoppern HPGR is

manufactured by a special powder-metallurgy process.


up to 2 400°C, and will be used primarily for investigating phase transformations and melting characteristics of materials for high-temperature applications.

Mintek, in partnership with the University of Cape Town’s Chemical Engineering Department, has been appointed by the DST to establish a Hydrogen Catalysis Competence Centre. This forms part of the implementation of the DST’s National hydrogen and fuel cell technologies research, development and innovation strategy that is to be officially launched in June 2008. A long-term goal of the strategy is the development of a local manufacturing base that will supply at least 25 per cent of the global demand for platinum group metals value-added products into the fuel cell sector by 2020. Products could include fuel cell catalysts, membrane electrode assemblies, stacks, fuel processors, and hydrogen storage systems, among others. The Hydrogen Catalysis Competence Centre will initially focus on the development of fuel cell catalysts, membrane

electrode assemblies, and fuel processors for use in combined heat and power, portable power, and fuel-cell vehicle applications that have been identified as important future markets for Proton Exchange Membrane (PEM) fuel cell systems. The first year will largely be devoted to establishing the centre, initiating the R&D programmes, and sourcing and commissioning fuel cell and stack testing facilities and fabrication equipment for membrane electrode assemblies.

FErroUS METalS InDUSTryTwo engineers from Mintek assisted in testwork, at a research facility in Germany, for the pre-reduction of vanadium-bearing titaniferous magnetite from the eastern Bushveld Complex, using about 100 t of concentrate prepared at Mintek by low-intensity magnetic separation. This follows small-scale smelting tests carried out previously at Mintek (Annual Report 2007). The Kermas Group, Samancor Chrome’s majority shareholder, plans to develop a 700 kt/a ductile iron project based on the resource,

which contains an estimated 150 Mt of magnetite ore at an average grade of about 60.8% Fe2O3 and 14.4% Ti2O5. The upper zone of the Bushveld Complex contains vast resources of titaniferous magnetite, which is exploited for iron, in some places. However, the titanium content of the one has never been factored into calculations of global titanium reserves, because there is currently no commercially available technology to beneficiate the titanium. Mintek is in the final stages of developing a technology that can upgrade the titanium content of a discard slag from the iron recovery process and render it into a saleable oxide titanium product.

As part of a Science Vote-funded project, a small-scale DC furnace was operated in submerged-arc mode (as opposed to the more usually employed transferred-arc configuration) to produce high-carbon ferromanganese and silicomanganese alloys from manganese ore. The results were benchmarked against a conventional AC submerged-arc furnace operation at a similar scale (about 150 kW). The results from the silicomanganese campaign are still being evaluated, but in the case of ferromanganese there was no significant difference between the manganese recoveries using an AC or DC operation. AC submerged arc furnaces for manganese alloy production are limited for electrical reasons to a maximum size below the economic optimum. The testwork represents a significant step towards overcoming this limitation.

In a project for a large ferro-alloy manufacturer, ferroniobium was successfully produced from de-phosphorised slag by aluminothermic reduction in a DC arc furnace.

Top left: Casting grinding balls from an experimental alloy.

Middle: Tapping the DC furnace.

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Left: The control room for the DC furnace facility.


A literature study has identified opportunities to investigate the use of a DC arc furnace to produce solar-grade silicon for photovoltaic cells. Historically, the solar industry has relied mainly on the supply of reject semiconductor-grade polysilicon, which is manufactured from metallurgical-grade silicon using trichlorosilane (SiHCl3) distillation and reduction. This production method is characterised by high energy consumption and large amounts of wastes containing environmentally harmful chlorine-based compounds and the product is expensive. The development of a direct route to produce solar-grade feedstock, with fewer steps, would reduce the cost of the product, and increase the reliability of the supply. Small-scale testwork on the proposed process is planned for 2008.

Mintek previously carried out bench-scale testwork on three different ore types (limonite, nontronite and saprolite) from Oriel Resources’ Shevchenko nickel laterite project to evaluate the leaching efficiencies and acid consumption. During the period under review, further laboratory work was conducted on purification of the leach liquor and precipitation of a mixed nickel-cobalt hydroxide product.

Two phases of a DC furnace chromite smelting project were completed successfully, utilising 5 t and 180 t of feed respectively, for a client in central Asia. The target ferrochromium quality was attained in both runs.

Fundamental and applied recovery testwork continued for Kumba Resources to evaluate processing options for the upgrading of iron ore from the Sishen South project and other orebodies. A research project funded by Kumba has begun

to investigate the magnetic separation of iron-ore fines and slimes with a particle size of less than 1 mm. Preliminary testwork was conducted to develop a flowsheet for the Zandrivierspoort magnetite deposit in Limpopo province, using selective crushing and milling, magnetic separation, and flotation. A model has been developed to predict the jigging response of iron ores using information from Mintek’s Mineral Density Separator.

Detailed mineralogical investigations were conducted on samples from four iron-ore deposits in India, followed by beneficiation tests and development of a recommended flowsheet. A total of 26 1-ton samples were submitted for the testwork, which consisted of dense-media separation and jigging of the coarse fractions, and multi-gravity separations and magnetic separation on the fines. A larger-scale programme of testwork for this project is anticipated in 2008. Magnetic separation methods were investigated for upgrading samples from Mount Nimba, one of the largest iron-ore deposits in West Africa.

The Innovation Fund project to develop more cost-effective grinding media has entered its second year, and good progress has been made in identifying potential steel alloys for this application. Production of grinding balls on a pilot scale is planned for the second half of 2008, and these will be subjected to marked-ball test (MBT) experiments in Mintek’s laboratory grinding mills. The aim of these experiments is to narrow the ball compositions to one or two recipes, which will, after optimisation of the composition, a batch of balls will be evaluated in extended testing in the industrial-scale grinding mills of the project partners, Anglo Platinum and Impala Platinum, during the final year of the project.

In the past two years, Mintek has been involved in initiatives to commercialise the outputs from two further Innovation Fund projects. The HerculesTM project, which involves the development of a low nickel austentic stainless steel grade for structural applications, is currently being commercialised with the assistance

Top right: A fractured mill-liner, one of the investigations conducted by the

Metals Technology Centre.

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Middle: The feed system and the electrode configuration (right) of the

refurbished DC arc smelter.


of a local technology transfer company, Licensing Technology Network (LTN), which is affiliated with Yet2.com as an authorised independent technology broker for South African technology. The Hercules technology was featured at the Yet2.com Executive Brief conference in Boston, Massachussets, USA in November 2007. Efforts are currently under way to secure funding to commercialise this technology. The Smartbolt® technology – a "smart" material for monitoring roof support conditions in mining applications – has been trademarked.

The Mintek Metals Technology Centre (MTC), which was formed to address the shortage of metallurgical skills in South Africa, experienced another busy year.

A total of 112 Metallurgical Evaluation Reports were completed, ranging from hardness tests on components to melting and casting of alloys, corrosion studies for material selection for plant construction, and failure analyses on various items of equipment. The young metallurgical graduates that passed through the system were in

demand, and took up positions in industry shortly after completing their training. We anticipate that the four trainees currently in the system will also move on to the industrial sector.

non-FErroUS METalS InDUSTryLarge-scale piloting of Mintek’s bacterial heap-leaching technology for low-grade chalcopyrite materials has been completed at the Sarcheshmeh Complex of the National Iranian Copper Industries Company (NICICO). Since early 2006, three 20 kt heaps have been leached. NICICO have constructed a further three leach heaps to test various design aspects such as aeration rate, particle size, and higher contents of primary sulphide material, and Mintek is providing off-site consultation to this ongoing work. Mintek and NICICO have entered into an agreement to jointly complete a feasibility study for the installation of a 14 000 tons copper per year commercial plant, utilising the technology, at the Dahrezar copper mine near Sarcheshmeh. Mintek has subcontracted a number of South African-based engineering

companies to complete specialised engineering components in the study, such as the design of the heap pads and cross-country pipelines. Completion of the feasibility study and the decision to proceed with the commercial plant are expected by the end of calendar 2008.

The heap leaching competency developed at Sarcheshmeh has led to further heap leaching service work. A range of heap leaching projects have been started not only for treatment of low-grade copper ores, but also for uranium and nickel ores. These include projects for overseas-based mining companies and ore deposits, but are mostly for junior mining companies exploiting base metal and uranium deposits in the southern African region.

The four-year BioMinE project, which started at the end of 2004 and is partly funded under the European Union’s (EU) Sixth Framework Programme, is nearing the end of its third year. This project has afforded Mintek the opportunity of working closely with European institutions on the fundamentals of biotechnology in mineral processing, and a number of methods have been developed for identifying and modifying micro-organisms using modern molecular techniques. Mintek is pursuing commercial applications in nickel and copper bioleaching in conjunction with European industrial partners, and these initiatives will continue after the BioMinE project comes to an end. An integrated piloting campaign for the leaching and recovery of nickel and copper from concentrate derived from the Aguablanca mine in Spain was started. A number of our European partners in the BioMinE project visited Mintek to participate in and discuss these piloting activities. Amenability work was carried out on material from the Bor copper mine in Serbia,

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Top left: Nickel hydroxide produced from the bioleaching of low-grade nickel concentrate.

Middle: Piloting the flowsheet for the Idaho Cobalt project.

Left: Cobalt "rounds". Electrowinning in this form reduces the risk of stress damaging the cathode.


which is being re-developed by an Austrian company, and piloting is scheduled for the second quarter of 2008.

A major activity under Science Vote funding has been the development of the HeapStar operator guidance system for heap leaching processes. The "professional" version of this package is now well advanced, and functionality testing using real heap leach data from the NICICO Dahrezar pilot plant has started. Mintek has signed a project with an Australian consortium for a package that includes an evaluation version of HeapStar and an instrumentation package for the Finders Wetar copper project in Indonesia.

Molecular biology techniques (real-time polymerase chain reaction or PCR techniques) have been established for identifying and quantifying bacterial types in tank bioleaching consortia. A Q-PCR machine for replicating DNA sequences in specific micro-organisms has been commissioned. This work will be extended to heap-leach systems during 2008. Progress is being made in research projects supported at the University of the Witwatersrand and the University of KwaZulu Natal on bioleaching of nickel laterites and diamond-hosting kimberlite, respectively. Good progress is also being made in research projects supported at Rhodes University and the University of the Free State on the biosynthesis of platinum and gold nanostructures, respectively.

A collaborative project with the Belarus Institute of Physical Organic Chemistry on the use of ion-exchange fibres for copper removal from cobalt electrolytes has been completed. It was found that the fibres have faster kinetics than granular ion-exchange resins, and the volume of the material required can be reduced by more than 90%, resulting in smaller, less

costly plants. However, the fibres have a lower capacity, and require larger volumes of sulphuric acid for regeneration. Mintek is looking to test the fibres on a larger scale at a mine site in 2008. The Institute is continuing to supply fibres on a commercial basis, and tests are planned on a range of additional applications, including scavenging PGMs from waste streams, nickel removal from cobalt electrolytes, and uranium and arsenic removal. Development of a new method of PGM analysis, using ion exchange fibres to concentrate the metals from solution, is also under consideration.

Laboratory testwork, consisting of crushing and dense-media separation followed by comminution and flotation, was completed as part of a pre-feasibility study by Norilsk Nickel on the upgrading of nickel-copper ore from the Selkirk deposit at Tati Nickel in Botswana. The results will be used to determine whether the ore can be upgraded to a feed suitable for the Activox® refinery. A study by the previous owner, LionOre Mining International, indicated that exploiting the low-grade mineralisation surrounding

the old underground workings at Selkirk could extend the life of Tati by more than 10 years. Mintek also investigated various methods of upgrading the discards from magnetic separation at Tati’s Phoenix operation, as well as a variability study on samples taken across the discards dump.

The results of evaluation work at Tati Nickel in Botswana on the Mintek-developed nickel synergist NicksynTM (Annual Report 2007) were presented at the Fourth Southern African Base Metals Conference in Namibia. Testwork at Tati continued during the period under review, and an approach has been received for trials on material from a Latin American laterite deposit.

Bench-scale development work was completed on the copper recovery and purification circuit for Mutanda Mining in the DRC. Further work is planned on cobalt recovery, which will be carried out in conjunction with a pilot campaign to evaluate the copper circuit. Similar small-scale work, involving comminution, leach optimisation, and cobalt recovery and purification, was completed for TEAL Exploration and Mining’s

Top right: Process development work for a copper-cobalt project in the

DRC.

Middle: Ion-exchange fibres.

Right: Iron and sulphate pollution in Spain’s historic Rio Tinto mining

district is caused by naturally-occuring sulphide-oxidising micro-

organisms.

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Kalumines copper-cobalt project.Mintek previously conducted

two mini-plant runs to develop a hydrometallurgical process for the Idaho Cobalt Project (Annual Report 2006). During 2007, a full piloting exercise was carried out, encompassing purification of the cobalt stream, nickel removal using the Ionex CIX pilot unit from Ionex Separations, and electrowinning in a divided cell to produce cobalt "rounds".

Improved analytical methods for the determination of both major and minor elements, to deliver better quality data for mass balancing in copper-cobalt piloting, have been developed and validated.

Characterisation testwork, including mineralogical investigations, dense media separation (DMS) and flotation, was carried out on samples from two zinc projects in Latin America - Sierra Mojada in Mexico, and Accha in Peru. The aim of the work was to separate the zinc minerals from the acid-consuming gangue in the ore

prior to recovery by leaching. Both projects were conducted under the supervision of Johannesburg-based project management company Green Team International (GTI), who managed the feasibility study on the Skorpion zinc project in Namibia on behalf of the owner. Heavy liquid separation and preliminary leaching tests were also conducted, as part of a prefeasibility study by GTI, on samples from the Omitiomire copper project in central Namibia.

A fundamental investigation was conducted on the use of magnesium oxide to remove cobalt from the bleed stream on a copper recovery circuit. This is usually done by cobalt-nickel solvent extraction, but the sodium hydroxide added to control the pH forms sodium sulphate, which constitutes an environmental liability. The work showed that magnesium oxide results in a very pure product with a cobalt hydroxide content of around 40 per cent, compared to between 20 and 30 per cent by the conventional route.

The government has identified

titanium as a strategic opportunity

for beneficiation and value

addition. This initiative, which

is being driven by the DST and

the DTI, embraces both titanium

metal and titanium dioxide

(TiO2) pigment. Mintek provided

considerable support to the

programme, including laboratory-

scale testwork to optimise

production routes, the assessment

and development of new

technologies for titanium metal

production, and techno-economic

studies of different technology

options and flowsheets. Mintek is

also participating in a programme

under the DST’s Advanced Metals

Initiative aimed at optimising

the properties of titanium metal

powder for direct fabrication of

components, which would reduce

the number of processing steps

needed.

InDUSTrIal MInEralSAt the end of the period under

review, Atomaer (RSA) Pty

Ltd began commissioning a

demonstration plant, employing

Mintek’s SAVMIN™ technology,

for treating acid mine water

at Randfontein, west of

Johannesburg. The technology will

be evaluated by Western Utilities

Corporation (Pty) Ltd, a subsidiary

of UK-based Watermark Global plc,

for treating contaminated water on

the Witwatersrand gold fields.

The SAVMIN process, which is

based on the selective precipitation

of insoluble sulphates, has

previously been evaluated and

demonstrated in three pilot

plant operations, at Stilfontein

Gold Mine, Navigation Colliery,

and Grootvlei Gold Mine. The

Randfontein plant, which

incorporates Atomaer’s Filblast®

Left: Laboratory work on the NicksynTM nickel synogist reagent.

24


Top right: Kimbolite indicator minerals garnet (pink) and ilmenite

(black).

Middle: The new Cameca electron microprobe.

reactor technology, has a capacity to treat 4 m3 of contaminated water per hour and represents the largest pilot evaluation of the technology to date. The plant is of a size that will demonstrate the engineering performance as well as the process chemistry, enable accurate determination of operating efficiency and cost, and ensure reliable engineering scale-up to full commercial application.

A Cameca SX50 electron microprobe has been commissioned, which significantly increases Mintek’s capacity for the in-situ geochemical analysis of minerals. The first commercial project on kimberlite indicator minerals for the diamond exploration industry was run on this instrument.

Mintek anticipates a large amount of similar work, and is hoping to establish a major service capability in this new area.

A large amount of gravity separation testwork, using heavy liquids, was carried out for De Beers. Mintek is the sole supplier of this service to De Beers.

A THRIP-funded investigation into the bioleaching of silicate minerals will be completed during 2008, and negotiations are under way to demonstrate on a larger scale the bio-accelerated weathering of kimberlite prior to crushing, which is aimed at facilitating the liberation of diamonds while reducing the chances of damage to the stones.

The South African Diamond and Precious Metals Regulator has granted R9 million towards the creation of a Diamond Provenance Laboratory at Mintek. The goal of the laboratory will be to combine physical characteristics such as size and spectral properties with chemical (trace-element) data to

cast light on the provenance of diamonds from alluvial deposits. Two senior staff members from the division were invited to participate in the European Commission’s Joint Research Centre workshop on diamond fingerprinting feasibility in August last year. Attendance at the "Antwerp World Diamond Conference SA Roadshow", the local "Diamonds – Source to Use" conference, and the quarterly "Kimberley Process South Africa Team" meeting, shows that Mintek is becoming well established in the South African diamond scene.

A new area of capability has been initiated in the field of quantitative mineralogical services for the construction industry. In collaboration with the University of Pretoria an attempt was made to manufacture clinker from manganese-mining waste. Although the material was not geochemically amenable, Mintek has begun using automated SEM techniques to characterise commercially manufactured clinkers. Allied to this project, an automated SEM examination of glass samples, was conducted, and Mintek will be looking at the

degradation of the refractory linings in glass furnaces with the aim of increasing the depth of experience that can be brought to slag analysis.

Uranium

The extended boom in uranium exploration has resulted in a continual stream of work in this field.

Extensive testwork, including flotation, uranium and gold leaching, and solvent extraction, was carried out for Mintails, which has the rights to exploit 323 Mt of surface tailings containing approximately 30.5 million pounds of U308 on the West Rand. In the 1980s, while the uranium price was at historically low levels, uranium recovery at the gold mines in this area was terminated, resulting in uranium-bearing slimes being deposited onto the dams after the gold had been recovered. The results indicate overall uranium recoveries of around 55 per cent.

Bench-scale comminution, scrubbing, and ion exchange testwork was done on samples from Trekkopje deposit in

Right: Part of the Atomaer SAVMINTM minewater treatment plant on the

West Rand.

25


Namibia, which is owned by Areva subsidiary UraMin, with the aim of determining the uranium distribution between the various fractions and the power consumption of the commercial scrubber. Leach optimisation was conducted for another Namibian project, being developed by Valencia Uranium, and this will be followed by ion exchange and solvent extraction work. An assessment of the ore and gangue mineralogy, comminution, and leaching testwork, were conducted as input to the pre-feasibility study for the African Energy Resources/Albidon Chirundu joint venture in Zambia. Mineralogical studies were started on core samples from A-Cap Resources’ Letlhakane project in Botswana in support of a scoping study by SRK Consulting, and this will be followed in 2008 by leaching and recovery testwork. The metallurgical testwork will include conventional and column leach tests to decide on the most appropriate process route.

Acid and alkaline leaching tests were conducted to determine

URANIUM TESTWORK

Top left: Leaching a sample from Bakouma, in the Central African Republic.

the most appropriate option for UraMin’s Bakouma uranium deposit in the Central African Republic. The Bakouma ore is rich in phosphate minerals, and this work also included the development of an improved ICP method for the simultaneous determination of uranium and calcium in matrices containing varying ratios of sulphuric and phosphoric acids. Comminution and solvent extraction work will continue in 2008 in support of a feasibility study.

South Africa aims to increase

the role of nuclear energy as part of the process of diversifying its primary energy sources, thereby reducing an over-reliance on coal with its attendant greenhouse-gas emissions, and addressing the growing demand for electricity. Many uranium prospects that were formerly considered to be uneconomic may be exploitable with the development of more complex processing technologies. In 2008, a Science Vote project will be started to develop a heap bioleach technique for low-grade pyrite-containing uranium ores. This will involve developing an understanding of the effect of gangue chemistry on scale-up factors and the in-heap generation of acid, ferric iron, and heat. Mintek has been granted Medium-Term Expenditure Framework (MTEF) funding by the Treasury, totalling R35 million over three years, specifically for uranium-related work, and is exploring a possible link with a Uranium Centre of Excellence in conjunction with the DST.

Above: Pressure leaching a Witwatersrand tailings sample.

Left: Ion-exchange separation work for the Trekkopje project in Namibia.

26

"The Mintek Metals Technology Centre (MTC), which was formed to address

the shortage of metallurgical skills

in South africa, experienced another

busy year."

research, development technology - mintek · meetings that include the 4th international symposium...

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