Search Documents

By F Shi, W Valery

WMC Fertilizers (WMCF) operates a Beneficiation Plant at Phosphate Hill in Queensland, Australia. The plant consists of two-stages of crushing, followed by a wet scrubbing and desliming circuit. Ore is then fed to a tertiary crusher and a milling/classification circuit, with the final product going to a swing-lift thickener and storage tanks. From the slurry storage tanks, the phosphate rock is fed to a horizontal belt filters which dewater the phosphate rock ahead of a hemi-hydrate phosphoric acid plant. The water soluble recovery of phosphate in the phosphoric acid plant is dependent on the moisture content in the filter cake, as this governs the wash water addition to the hemi-hydrate filters. Since commencement of operation, the moisture content of the filter cake fed to the phosphoric acid plant has been higher than design reducing the phosphoric acid plant recovery and at times reducing the throughput through the phosphoric acid plant. The moisture content in the filter cake can be decreased by reducing the generation of fines in the milling and classification circuit (classified as û38 micron material). This paper identifies the causes of fines generation in the Phosphate Hill beneficiation plant. It discusses the options that were assessed to minimise fines generation, and outlines the results to date of circuit changes undertaken at Phosphate Hill.

Jan 1, 2003

By K Le Bron

Fatalities that occurred because of rock falls in off-reef excavations (excluding shafts) over the last three years range between ten per cent and 20 per cent of the total number of fatalities that have occurred due to rock falls in the South African mining industry. These rock falls, mostly exacerbated by blasting practices, occur because of failure on discontinuities within the rock mass. Among other reasons of their occurrence is insufficient support installation or the incorrect assessment of rock mass conditions. This report presents qualitative analysis intended to outline rock stability conditions in tunnels subjected to dynamic loading. Seismic waves including those created by firing an explosive charge in tunnel rocks are considered. The rock behaviour is monitored using geophones and extensometers variably installed to record the near and far effects of roof bolt support units on a dynamically loaded rock. The paper discusses the results of field investigations.

Jan 1, 1999

By Nye P. B, Fisher N. H

At the second Empire Mining and Metallurgical Congress held in 1927, the Empire Council of Mining and Metallurgical Institutions was formed and it was proposed that the Council take steps to prepare a "Review of the Mineral Resources and Industries of the Empire." At the third congress in 1930, it was resolved that the proposal to institute the review should be submitted to the Imperial Conference held in 1930. This was done, and the Minerals Committee, of the Imperial Economic Committee compiled, an interimreport which was based on statistics of imports and exports, and did not consider resources and consumption.In 1942 the Institution of Mining and Metallurgy, London, wrote to the Empire Council and stated that it was desirable that the Council should be in a position to take part in decisions affecting the future of the mining and metallurgical industries. The Council communicated with the constituent Institutions regarding the nominations of two members then in England. Subsequently the Mining, Geological and Metallurgical ,Institute of India prepared a review of the mineral resources and industries of India and their post-war development, and the Empire Council forwarded a copy to the Australasian Institute of Mining and Metallurgy and asked if that Institute would submit a review on simjIar lines for Australia. The Australasian Institute arranged that the Australian review should be prepared by...

Jan 1, 1946

By Miller D. R

The mineral exploration and extraction industries have gained major cost and efficiency benefits from the use of computers. However these industries are now at a cross-roads with two seemingly disparate developments - that of an increasing number of complex geoscience databases and, at the same time, the merging of all known data for the particular regions at minimal cost. These two developments can be managed by the development and of an industry accepted geoscience data model and dictionary. This will provide a common basis of understanding for geoscience data through a common language and a common structure for geoscience information. Integration of specialist systems and databases can then proceed efficiently. The development of a data model is going ahead with consensus from the mining industry. This is a joint government and industry funded project and managed through the Australian Mineral Industries Research Association, AMIRA. AMIRA is a well known research broker to the Australian mining industry obtaining sponsorship for projects both from private and government groups. The AMIRA project, P431, called the Geoscience Data Model, is to be the Australian standard data model for geoscience disciplines. The requirement for a standard geoscience data model has been recognised in Australia for some time. In October 1991, the Australian Government Geoscience Database Policy Advisory Committee (GGDPAC) established a Geoscience Data Standards Working Group which drafted a comprehensive list of data categories of the geoscience area. An AMIRA project called AMDEX was established to develop a transfer standard for the mining industry data at about the same time as this committee was in operation. The first AMDEX sponsors meeting was held in May 1991. It was proposed to use the US Spatial Data Transfer Standard (SDTS) as the basis to transfer mining data in AMDEX. A limited data model of mining data to be transferred was developed for the AMDEX standard under SDTS. The Australian Geological Survey Organisation (AGSO) saw the need to extend this and develop a complete data model for the geosciences and proposed this as a new project to AMIRA. This was strongly supported by GGDPAC which lead to sponsorship of the project from most state geological surveys. The Geoscience Data Model can be broken down into separate data models for a number of geoscience themes and sponsorship obtained so far will enable models to be developed for a comprehensive set of themes selected by the project sponsors. Further sponsorship is required to enable a more complete coverage of the geoscience area to be developed. Sponsorship for the Geoscience Data Model has been strong from the geological surveys and there was some effort by GGDPAC to promote the project in these organisations. An Australian geoscience data model is of immediate use to the geological surveys in assisting the standardising of huge quantities of geoscience data held by government agencies and it is preferable that this be an Australia-wide standard.

Jan 1, 1995

By T Gready

Stawell Gold Mines operates the Magdala underground mine in western Victoria, Australia. Several orebodies are extracted by longhole open stoping at a depth of 900 m below the town of Stawell. Some stopes are backfilled with cemented slurry rock fill (CSRF) to ensure stability, increase recovery of ore reserves, minimise dilution of ore grades, and add value to the project. StawellÆs simple CSRF system is described, including the novel equipment used to minimise capital costs. Design criteria, operating procedures, monitoring systems and results are discussed in detail. Practical aspects are considered, including lessons learnt about barricades, overbreak and segregation. The economics of CSRF are discussed, including capital costs, operating costs and the total cost per ounce of gold poured. Options for mining with and without CSRF are compared in terms of return on investment and net cash flows. Examples demonstrate the method used to calculate æbreak-evenÆ stope ore grades which determine whether or not CSRF will add value in different circumstances.

Jan 1, 2002

Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

By Hedge AS

Mt Whaleback is one of the largest open-cut iron ore mines in the world. Haulage cost is the single largest component of operating costs at the mine. Past studies towards alternatives to truck haulage have recognised the potential viability of an in-pit crushing and conveying system, dependent on the proportion of uphill haulage. After seventeen years of mining Mt Whaleback still contains more than 1,000 million tonnes of ore, needing 1,800 million tonnes of waste removal to extract it. What was once a quarry has now turned into a large open pit. The increasing proportion of uphill haulage, the need to replace ageing 120 ton and 200 ton trucks and the necessity of achieving and maintaining a higher stripping ratio prompted, in 1984, the initiation of a new feasibility study into the viability of alternative material handling systems. A semi-mobile in-pit crushing and conveying system was found to be most suited to Mt Whaleback conditions. The East Pit was selected as the best location based on the analysis of haulage profiles measured on long term incremental mine plans. A capacity of 22 million tonnes per year was considered achievable by the proven technology currently available. A detailed estimation of capital and operating costs of two systems - one with trucks only and another with trucks, crusher and conveyor - for the removal of 22 million tonnes per year of waste rock, showed substantial cost savings achievable by the proposed system. An economic evaluation of the two systems established the advantages of constructing the in-pit crushing and conveying system. This is now under construction and will be commissioned in early 1987. Experience gained in constructing and operating this installation is expected to influence decisions on similar installations in future.

Jan 1, 1986

By Wharton P, Voigt R

In order to do the discharge estimation better, it is valuable to find out appropriate formulas for estimating discharge in various pits, based on accumulating data, summarizing discharge patterns applying optimum seeking method and principle, by seeking redical exponent with help of the method of exhaustion, as well as testing and making statistics, in accordance with the quality standards established by our practical experience.

Jan 1, 1988

In todayÆs demanding business landscape continual change and technological advancement is a given. With these changes there is now, more than ever, a need to ensure sustainable growth in respect of value protection and value adding whilst meeting the pressures and expectations of the societies in which we operate. Traditionally the management of safety has been a very reactive activity in the business, in some cases seen as an irritation and a disruptive process that demands a focus on preventing reoccurrences. This in turn has focused the measurement of safety performance on a range of lagging indicators û æafter the effect managementÆ. Gaining and maintaining a licence to operate is crucial to a sustainable business but as a prerequisite, organisations need to have a demonstrable ability to manage the safety of their people, as well as mitigating the people risk associated with the business activity. A major focus in the last decade has been on the implementation of enterprise risk management programs, where risk becomes embedded in all business systems and processes and the organisationsÆ genetic make up is programmed to analyse and integrate risk management into all facets of the business activity. The management of safety should be no different. One school of thought argues that there are no new accidents, but rather our inability to learn from the past. Others believe that as long as we have an appetite to achieve the unachievable, we will have to continue to push the boundaries, our safety comfort zones and inevitably take risks. Single reliance on highly evolved technical systems, elaborate processes, highly skilled people, safe equipment and safe work environments have shown one thing û they are not sustainable in providing adequate coverage in the business. In analysing a range of factors associated with some of the worst catastrophes of the 20th century, it can be suggested that they were in fact predictable and inevitable and that an integrated approach underpinned by sound risk management systems could have determined a different result. The key to a sustainable approach in the management of safety requires us to look at a multitude of aspects that collectively allow the performance of an organisation to be predictable. To have certainty in the business activities it is necessary to have controls in place that will mitigate the risks normally associated with unwanted events. It is ensuring that human factors effectively contribute to monitoring the planned approach and being able to safely adjust to any variability. In essence this is having the ability to proactively plan for the longer term. The sentiments articulated by organisational leaders echo that safety management is good business. Surely then a good business is a sustainable business, and a sustainable business is one that provides lasting benefits to its stakeholders.

Jan 1, 2006

By C Kusi-Manu, E Nyamusika

Geita Gold Mining Limited (GGML) is owned and jointly managed by Ashanti Goldfields Company (Ghana) and Anglogold (South Africa). The mine is currently one of the largest gold producing open pit operations in Africa producing 620 000 ounces of gold and mining in excess of 70 000 000 tonnes of material per annum. The mine currently has 2000 full time employeeÆs and a mine life in excess of 12 years. Geita Gold Mine is comprised of 11 different gold deposits situated in the Lake Victoria Goldfields of North Western Tanzania (Figure 1). The gold deposits are primarily associated with banded ironstone formations within an Archaean greenstone belt. Current global resources, including Inferred, stand at 129.5 million tonnes grading 3.91 g/t (16.2 M oz). Open pit reserves total 70.4 million tonnes grading 4.16 g/t (9.4 M oz). The majority of the gold resource is hosted by the three deposits (Nyankanga, Lone Cone and Geita Hill) within the æGeita TrendÆ a large and continuous (>4 km long) mineralised zone (Adofo, 2002). Geita Gold Mine commenced operations in June 2000, as the second large-scale open pit gold mine in Tanzania. The new workforce of 800 people had no previous experience in open pit gold mining. Since the start of the operation, Geita Gold MineÆs management ambition was to become a world leader in the application of best practice in all technical disciplines and in operational success. Staff development and training was identified as one of the major components in the company achieving its aim. Geita Gold MineÆs management has committed the necessary training staff, resources and the commitment of over $US 1 M a year to staff training and development programs for 2003 and 2004. The process and management of Geita Gold MineÆs mining geology staff training and development program is presented in this paper.

Jan 1, 2003

The stratigraphy of the Singleton Coal Measures is reviewed and a revised stratigrapixy which has been ratified by the N.S.W. Standing Committee for Coalfield geology is nominated and defined by a selected type section. Withir the type section the occurrence of repetitive phases are illustrated and described. Coal. Measure units within the Singleton Coal Mean sures, termed the Wollombi and Wittingham Coal Measures respectively, are correlated with the Newcastle and Tomago Coal Measures. In formal nomenclature the Singleton Coal Measures are designated the Singleton Super Group. The major depositional cycles within the Coal Mea- sures are outlined together with those lesser phases within the Coal bearing sequences that influence the mining conditions likely to be encountered. Both tectonic and sedimentary features of the Singleton Coal Measures are considered and the localized post depositional effects on the coal seams and roof strata in- duced by differential, compactions are emphar Sized.

Jan 1, 1972

Stringent environmental benchmarks imposed by governments and successful legal challenges in the country of origin have changed the risk profile for all mining companies over recent years. In developing countries, however, where high government standards may not always be in place, direct community action has often made worthless substantial investments in otherwise viable mining operations. Real limitations are therefore imposed from these risks on all areas of mining activity, wherever they may be. Thus, the bar has been raised for all companies developing or operating mines. This paper argues real financial and global industry reputation benefits accrue when all known environmental risks, where practical, are managed. In response, among major international mining companies, as the industry moves towards greater global consolidation, senior management teams have increasingly adopted corporate governance standards including æTriple Bottom LineÆ (shareholder/government/community) sustainability reporting. Sustainability reporting is encouraged by improved international stockholder and financial investor perceptions by contributing to lowered social, community and geopolitical risk which lowers the cost of access to funds as well as improving staff morale and productivity. New mines must not only be primarily financially viable but must operate throughout in a sustainable way. Case studies of some recent mining operations, who have not foreseen or proactively managed major environmental risks, demonstrate the dire financial and personal implications for managers, directors and shareholders from not identifying and managing these environmental risks. Merely having a corporate policy statement on environmental standards or high level Government approvals process for a mining activity does not preclude mining operations from the risk of direct action by local populations or future adverse legal implications from risks which were perhaps identified but not mitigated effectively. Methods and processes for the identification and active management of environmental risks in the global arena are discussed to add a practical element to sustainability, based on the authors recent strategy development processes with governments and major mining houses such as BHPBillition, Rio and Xstrata. Emphasis is placed on proactive, innovative yet practical solutions which, where possible, show positive contributions firstly to the financial bottom line but also the community at large.

Jan 1, 2003

DCF Valuations are very important to individuals and companies involved in the mining industry. Such valuations are critical to investment decisions in relation to new and existing projects. In particular they provide fundamental information to shareholders in the event of a capital raising or takeover and to financiers supporting mining companies and projects. Also, DCF Valuations are often used to support asset carrying values in the financial statements of mining companies. This paper presents a Chartered Accountant's (CA's) perspective on the main issues to be considered in preparing, analysing and relying upon DCF methods in mineral valuations and provides some practical examples relating to key issues. The paper makes the important point that DCF methods involve making assumptions about future events and circumstances that inherently contain uncertainty which results in a valuation prepared on a DCF basis providing a range of values that are not perfect or accurate. In order that DCF valuations provide meaningful information the underlying methodology used and assumptions made must be consistent, sound and well supported. Credibility of those involved in preparing mineral valuations is vital and this paper supports the adoption of sound practices by all concerned.

Jan 1, 1994

The major slime forming minerals in coal seams are generally montmorillonite, illite and kaolinite, and due to the consistant trend to full seam mechanisation in New South Wales and Queensland these minerals remain in the feed to a coal preparation plant. After coming into contact with water their size degradation is very rapid, and therefore they mostly report to the fine coal cleaning section of the plant. Froth flotation, being the most effective method of beneficiating fine coal, is widely practised in these two major coal producing states of Australia. Plant experience and laboratory tests suggest that the presence of these slimes in the flotation circuit depresses the flotation of fine coal. Although the deleterious effects of slimes on the flotation behaviour of minerals is well known, the mode of their adsorption at the mineral surface has been a subject of controversy for some time. In this paper, on the basis of the surface properties of slime forming minerals and coal, a model has been put forward to explain the adsorption of slimes at the coal surface. The degree of slime coating has been examined by scanning electron microscopy. Laboratory tests have revealed that with the appropriate use of polyvalent phosphate electrolytes these slimes can be liberated from the coal surface. Just attrition and desliming are not enough to ensure complete liberation of slimes. Coal, after treatment with these electrolytes and then deslimed, floats readily with a common frother, such as MIBC. Modifications in the conventional flotation circuits have been suggested to ensure an efficient flotation of fine coal.

Jan 1, 1978

By J Bartlett, P Quigley

Historical research has played a significant role in the rebirth of the Bendigo Goldfield. The historical research undertaken by the company has been directed to specific areas such as verifying the total gold production of the field, the gold production from defined blocks on each of the major anticlines, the extent of workings of each mine which exceeded 200 m depth, the size and style of reefs mined in each shaft and also within specific domains of the field. Application of this data has assisted in the determination of possible dimensions of different reef styles and the location of mineralisation within each reef system. Description of grade variation, percentage of quartz and the amount and species of accessory sulphide minerals, as well as early geotechnical observations accompanying stoping methodologies, provides valuable analogues for reef structure being defined in the current program. Historical information on shafts on the two anticlines the company is exploring has allowed the postulation and recognition of repetition of reef development within the same stratigraphy in the hinge zones of the adjacent folds. The similarities of mineralisation styles across the field within both specific lithological units and structural setting has had important implications in respect to exploration drill targeting and the estimation of grade and tonnes.

Jan 1, 2003

The story of the rise, progress, and development of our modern railway system is a long but an exceedingly interesting one. The phases it has passed through, the discussions that have arisen from time to time on the most economic modes of construction and working, and the final result these various discussions have led to, are full of importance and interest to the engineer. It is not my intention to deal historically with the subject. I desire simply to speak to the requirements of the hour in Australia. It will not be disputed, I think, that these colonies have reached a point in railway construction and management when, if additional lines to any extent are still to be built, a different principle must be adopted. There are yet large tracts and areas of country to be tapped by the rail and the locomotive, which for years to come must remain untouched if the same expensive gauges and modes of construction are continued. We have yet to see clearly the necessity of introducing a system of light lines that will pay their own way and at the same time augment the traffic of our main lines. This question really no longer remains an unsolved problem. It lies, in a few words, in the acceptance of the, narrowest gauge and the simplest mode of construction that can constitute a pacticable railway. I fear it is hopeless to suggest that private companies should be legally permitted to construct such lines. It seems as if it were next to impossible to move official authorities to enter upon the construction of lines on this principle. It is, all the same an undoubted fact that if private companies could obtain Acts of Parliament, that in several of the colonies a new impetus would be given to railway construction.I may point out that not only has the principle of narrow gauge light railways been adopted in India but private companies are obtaining power to build them. Outside of :England many narrow gauge lines have been made, and in France, Denmark, Italy, and Sweden they have been highly successful.

By Y Lin, B J. Seligmann, M Hassall, S Micklethwaite

For multi-site mining companies, checking the quality and consistency of the data recorded in risk registers is important for confirming how well mine safety management systems have been implemented. However, this task is complicated by the differences in scope of the site, their particular nature, the complexity of the operations and many other factors that can introduce nuances to the characteristics of the risk registers. We present here an application of a technique called Causal Network Topology Analysis for comparing the quality and consistency of risk registers. By quality we refer to, for example: - missing causal relationships between risks - location of missing controls - focus of risk treatment strategies: prevention versus mitigation controls. By consistency we refer to how causally interdependent are the risk events. There are often causal interactions between the lines of a risk register that mean that the likelihood and consequence scores that are applied to each risk event are not independent. We measure this degree of interactions by: - proportion of independent scenarios per register - efficiency of risk treatment strategy comparison. This approach can indicate quality and consistency differences between registers irrespective of the actual details of the site or operation. This occurs by comparing aspects of the structure of a causal network extracted from how the risk events, causes, controls and consequences causally interact. In this work we compare pairs of registers to demonstrate the approach.

Apr 16, 2024

By Basillo CI

The adsorption mechanisms of various thiol collectors can be subdivided into four classes: chemisorption, EC-mechanism, catalytic oxidation and metathetical substitution. The chemisorption mechanism occurs at potentials below the thermodynamic potentials for the metal-thiol compound formation and is reversible. The EC-mechanism occurs when the mineral is sufficiently oxidised to liberate metal ions to form metal-xanthates; therefore, it is observed with more easily oxidisable minerals and/or with collectors having large pK values. Thionocarbamates adsorb on sulphide minerals via the EC-mechanism due to their large pK values. Although the adsorption occurs at very low potentials as compared to xanthates, it is irreversible with large overpotentials. On the other hand, the adsorption of modified thiophosphates and thiophosphinates occurs near the thermodynamic potentials because of the low pK values. The metathetical substitution is believed to occur only when a mineral is highly oxidised. These classifications are useful for studying the effects of electrochemical potentials and the molecular structure on the collector adsorption Mechanisms.

Jan 1, 1993

Prior to the merger of BHP and Billiton, both companies had a keenfocus on improving their performance in health, safety, environment and community (HSEC) matters. This shared intent, albeit executed insomewhat different ways, provided an excellent foundation for the newCompany. During the integration planning phase, a team was formed toconsider the organisational design for consistently achieving world class HSEC performance. The design included the policy platform, resources, structures, standards and procedures to be implemented in the merged entity. A key aspect of the design was the fully integrated HSECManagement Standards. These Standards create the framework for theconsistent application of BHP BillitonÆs HSEC Policy at all of ourmanaged operations across the world. The Standards have their origin in similar frameworks adopted by BHP during the 1990s, as well as thewell-known quality related standards (eg ISO 14001). However, they areunique in that they combine all aspects of HSEC management into asingle integrated set of auditable standards. By combining these areas and integrating our HSEC Management Standards with other aspects of the æBHP Billiton WayÆ, we are establishing a holistic, line management driven improvement approach. Over time, the BHP Billiton Way will embed a systematic improvement philosophy that we expect will become a key source of competitive advantage. The HSEC Management Standards are consistent with ISO 14001,OHSAS 18001, the Australian Minerals Industry Code for EnvironmentalManagement and generally aligned with SA8000. While compliance withthese external standards ensures that a systematic approach andimprovement plans are in place, BHP BillitonÆs HSEC Standards gofurther to include minimum performance requirements that reflect theintent of our HSEC Policy. Therefore, implementation at site levelensures that robust systems are in place to implement our Policy and that accreditation can be achieved to external standards if required.To assess implementation of the HSEC Management Standards anaudit system has been designed which incorporates both self-assessmentand peer review. Each site is required to undertake an annualself-assessment of compliance with the Standards using a commonassessment protocol. Every three years a peer review is conducted at each site to confirm the results of self-assessment and to provide a means of sharing knowledge throughout the Company. The review teams are composed of line managers and HSEC professionals from around theCompany, representatives of our joint venture partners and independentspecialists as required. The Company has committed to public reportingof the audit results through our annual HSEC report and this is reflected in our published targets. From a wider perspective, as we in the resources industry strive tocollectively raise our HSEC performance and reputation, there may be arole for industry based HSEC Management Standards complemented bya level of independent review.

Jan 1, 2002

By P Duuring

Late-Archean banded iron formation (BIF)-hosted deposits in the Yilgarn Craton of Western Australia are less well understood compared to the larger Paleoproterozoic, Superior-type BIFhosted deposits of the Hamersley Province. The Weld Range greenstone belt, in the Murchison Domain of the Yilgarn Craton, hosts two Archean, high-grade deposits, Madoonga (68 Mt resource at 57.7 wt per cent Fe) and Beebyn (62 Mt resource at 59.6 wt per cent Fe, ASX announcement 2008). Five main types of high-grade (>55 wt per cent Fe) iron mineralisation at Weld Range each display characteristic grades, tonnage, and contaminant levels, which affect exploration strategies and beneficiation methods:1. ‘Residual’ ore formed as a result of two generations of hypogene alteration of BIF. The first alteration phase replaced silica-rich bands with siderite and/or Fe-rich dolomite; the second phase involved the removal of carbonate gangue minerals and the concentration of residual Fe oxide-rich bands in the BIF via volume reduction. The product is a high-grade, high-tonnage Fe orebody, with minor contaminants.2. Magnetite-bearing shear and fault zones cut BIF along lithological contacts. These zones of secondary magnetite formed as a result of the addition of hypogene magnetite via the circulation of Fe-rich, hypogene hydrothermal fluids through BIF. This type of mineralisation produces narrow (low-tonnage), high-grade magnetite-rich ore zones with high levels of contaminants (eg SiO2, Al2O3) due to the difficulty in mining these zones.3. Specular haematite ± quartz-bearing shear and fault zones cut residual orebodies and magnetite bearing structures. They share similar characteristics to magnetite-bearing structures.4. Goethite-haematite supergene ore zones are controlled by brittle faults that cut BIF. These faults promoted the flow of supergene fluids through BIF and resulted in large ore zones with variable Fe grades and contaminants.5. Detrital deposits comprise transported BIF fragments and are intensely goethite-haematite supergene-altered. These orebodies are locally extensive, with moderate Fe grades.

Jul 11, 2011