Search Documents

Iron formation-hosted iron ore deposits account for the majority of current world iron ore production and consist of three classes: unenriched primary iron formation with typically 25 to 45 wt per cent Fe; martite-goethite ore formed by supergene processes, with abundant hydrous iron oxides containing 60 to 63 wt per cent Fe; and high-grade hematite ores thought to be of hypogene or metamorphic origin overprinted by subsequent supergene enrichment with 60 to 68 wt per cent Fe.Individual iron ore deposits range from a few millions of tonnes to over two billion tonnes at >64 wt per cent Fe, although most are within the range of 200 to 500 Mt. In the Hamersley Province of Western Australia, martite-goethite ores are largely developed in the Marra Mamba Iron Formation, although high (>0.08 per cent P) phosphorous mineralisation is also well developed in the stratigraphically higher Brockman Iron Formation. Whilst the vast majority of high-grade microplaty hematite ore is best developed in the Brockman Iron Formation, this paper provides the first textural evidence of locally significant microplaty hematite mineralisation in the Nammuldi Member of the Marra Mamba Iron Formation, in the Chichester Ranges at the Christmas Creek, Cloud Break and Mount Nicholas prospects. Petrographic studies have identified a high-grade Fe texture composed of nanometre scale plates of hematite in mineralised sections of primary microplaty hematite deposits in the Pilbara and elsewhere, well below the normal depth of weathering or dehydration. The population of nanometre to micrometre scale hematite plates is interpreted to represent various stages of nucleation, crystallisation and progressive growth of hematite from the primary ore-forming fluid in areas that were once iron-rich carbonates or silicates in the BIF.

Jan 1, 2005

By P Card

Some project managers accept unsatisfactory economic evaluation modelling because they are unaware of what constitutes good practice. They tend to leave it to the evaluation specialist or others to decide. The AusIMM has published on its website a draft set of guidelines for technical economic evaluation which will allow these project managers to take control and demand worldÆs best practices.The style of the guidelines is described and the source of a worked spreadsheet example in Excel is given.Economic evaluation in project management is described. A simple test for the acceptance or rejection of evaluation work is offered. The nature of modelling and evaluation in each of the three study phases of concept, prefeasibility and final feasibility are described. Suggestions on the selection of specialists for each phase are given. The three levels of evaluation thinking are described, namely, modelling, valuation and evaluation. Finally the meaning of æfinancial analysisÆ is explained.The conclusion is that æthe role of an economic evaluation specialist is to create models and evaluations for the whole project team to readily understand and use: it is not to create models for his/her own useÆ.CITATION:Card, P, 2012. What project managers must demand from an economic evaluation!, in Proceedings Project Evaluation 2012 , pp 173-176 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By D Schwab, R M. Tosdal

The Quesnell-Stikine arcs, in the Canadian Cordillera, are host to Triassic and Early Jurassic alkalic porphyry Cu-Au and calc-alkalic porphyry Cu-(Mo-Au) deposits formed outboard of ancestralNorth America in island-arc tectonic settings (McMillan, 1991). The majority of the alkalic porphyry Cu-Au deposits are products of a discrete magmatic event at the end of the Triassic, with a second and smaller event in the Early Jurassic (Mortensen, Ghosh and Ferri, 1995). Of the Triassic complexes, the Galore Creek alkalic intrusive suite is one of the largest and most silica-undersaturated intrusive complexes, and host to the most significant undeveloped alkalic porphyry Cu-Au resource in North America (Lang, Stanley and Thompson, 1995). Because of the common presence of feldspathoidal-bearing rocks in the complex (Enns et al, 1995), Galore Creek likely represents an end member example of the alkalic porphyry Cu-Au class. The Galore Creek alkalic Cu-Au-Ag porphyry district, located in NW British Columbia (Canada), contains 12 mineralised prospects (Enns et al, 1995; Micko et al, 2007; Schwab et al, in press) with a total measured and indicated resources of 785.7 Mt at 0.52 per cent Cu, 0.29 g/t Au and 4.87 g/t Ag (NovaGold Resources Inc, February, 2008). The Central Zone is the largest and best delineated. Other economically important mineralised centres include the South-West, Bountiful, West Fork and Junction deposits. The South-West Zone, the focus of this contribution, is a Cu-Au-Ag breccia-centred deposit with a measured and indicated resource of 69 Mt grading 0.42 per cent Cu, 0.69 g/t Au, 2.67 g/t Ag. Hosted in brecciated intrusive rocks, the South-West Zone is distinctly younger than the Central Zone and most of the other mineralised centres (Enns et al, 1995; Schwab et al, in press). The South-West Zone therefore preserves the late stages of hydrothermal evolution at Galore Creek. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By C A. Foss, K Leslie, C Arnold

Magnetic susceptibility measurements provide rapid, non-destructive testing of drill core, but cannot directly map magnetite and/or hematite content. Combined magnetic susceptibility and magnetisation measurements provide much more diagnostic information and, with sparse calibration constraints, are able to quantify magnetite and hematite concentrations and potentially map differences in grain size and texture. We have developed a travelling three-component vector magnetometer that can be run alongside core to map its external magnetic field. The logger has been designed to operate in core sheds and at remote drill sites. It is used to rapidly scan a length of core, with each core being scanned in different rotations. The magnetic field contributions from any remanent magnetisation rotates with the core and cause differences between successive measurements, while the field contributions from any induced magnetisations with isotropic magnetic susceptibility remain constant. Deconvolution of the magnetic field data with simultaneous three-channel inversions of the multirotation data separates remanent and induced components. Interpretation of this data provides estimates of the intensities of induced and remanent magnetisations, the orientation of the remanent magnetisations and the ratios of the induced and remanent magnetisation strengths. We expect these magnetisation parameters to correlate with stratigraphy through a banded-iron formation. Furthermore, we anticipate that we will be able to use this information to map zones of oxidation and other changes along the core. This novel instrument is one component of an integrated CSIRO program to provide new capabilities for iron ore exploration and development based on studies of magnetic fields and magnetisations at scales ranging from centimetres for these core investigations to tens of kilometres for formation studies.CITATION:Foss, C A, Leslie, K and Arnold, C, 2015. Rapid logging of different magnetic phases in banded ironstones using a travelling three-component vector magnetometer, in Proceedings Iron Ore 2015, pp 271–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By B McFadyen, Y Potvin, K Woodward

The Australian Centre for Geomechanics (ACG) held two workshops in 2019—one in Australia and one in Canada—to discuss processes and methods currently used in the mining industry for stope design and reconciliation. In practice, this work strives to optimise stope performance and aims to maximise ore recovery (minimise underbreak), while minimising dilution (overbreak). One of the key findings from the workshops was that current stope design practices, almost exclusively, rely on some versions of the empirical Stability Graph methods developed in 1980s. Although robust and useful at the feasibility study stage, there are a number of inherent shortcomings with this approach. The Stability Graph’s limitations first lie in that it cannot assess underbreak, which is a very important measure of performance. Furthermore, the method doesn’t consider a number of factors which often have a critical influence on stope stability, for example, drilling and blasting or the presence of faults. Given the current industry standard practice, there is a great opportunity to reinvent the stope design process to optimise performance. A finding of the workshops was that every mine quantifies stope performance in terms of volume reconciliation with a focus on dilution and ore losses, and reconciling metal tonnes recovered from the mill. Many mines further investigate stope performance by looking at individual stope faces and the causes for the deviations between the planned stope shape and the measured cavity. Recent research at the ACG has shown that investigating overbreak and underbreak at a higher resolution is a powerful way to identify the root causes of overbreak and underbreak. Finer scale assessment is achieved using an octree analyses, which effectively divides the relevant stope volume into cubes on the scale of a metre and produces many tens of thousands of data points. The octree data structure and subsequent analysis underpins a data-driven stope design methodology. The ACG is currently developing a design approach based on multivariate modelling methods that can account for the many variables that influence stope performance and forecast stope overbreak and underbreak results. Back-analysing stopes based on octree reconciliation results provides a rich database for training the model. Once the model can achieve reliable forecasting of overbreak and underbreak, an interactive drill-and-blast design will allow for the assessment of different firing strategies to optimise stope performance.

Mar 15, 2021

By Gray E, Banks J

In mine site revegetation, exotic grasses are more commonly used than native grasses. This is due to unavailability of native grass seed on a commerical scale and lack of information on agronomical aspects of native grasses. This paper lists a number of native grass species that have the potential to grow well on mine sites, and provides some information on their seed collection, processing and germination. Further, it demonstrates via results of a field trial conducted at Ranger Mine spoil the relative performance of ten native grasses and Rhodes grass. It is concluded that (i) some native grasses have similar ability to grow on mine spoils compared to Rhodes grass and (ii) the use of native grasses have added advantages in ecosystem restoration.

Jan 1, 1994

By M Alston

Many organisations struggle to yield meaningful outcomes from incident investigations. This paper will demonstrate that we can discover systemic issues by rethinking the ‘Why’ and ‘How’ of investigations, fostering genuine risk reduction. Key points: 1. Shift from ‘prevent recurrence’ to ‘learn and reduce risk’: conventional investigations focus narrowly on recurrence prevention, resulting in narrowly focused investigations with limited ability to identify and reduce organisational risk. Redirecting our objective to learning and improvement opens avenues for broader risk mitigation. 2. Understanding daily work for risk insights: recognise that work is not always completed in full compliance with procedures. Workers will adapt how they complete tasks influenced by the conditions and management systems that exist every day. Understanding the conditions and systems affecting everyday work is vital for uncovering systemic risks. 3. Unearth systemic issues through in-depth exploration: many investigations address surface concerns such as lack of training, incorrect procedures, equipment not being maintained, and missing overarching organisational risks. Systemic, organisation-wide risks are not identified. To discover these systemic issues and create shared learnings, investigators must question management systems, including resourcing, planning and risk management. 4. Design actions for safe failure: common actions like discipline and training fall short and do not reduce risk. Resilience emerges from well-designed controls. Incorporate planning, better resources, interlocks, and guarding to bridge the gap between task execution and risk. 5. Investigation Reports as a Business Case: Investigation reports should not simply state historical information regarding an incident. They are to facilitate decision-making and be presented as a business case to drive change. Organisations can move beyond localised risk and ineffective administrative actions by changing investigation objectives and methods. They can facilitate learning, understand daily work intricacies, identify systemic issues, and enhance the capacity for safety, driving lasting risk reduction.

Apr 16, 2024

Gold mineralisation at the Kerimenge-Lemenge prospects is a classical example of myltiple, overprinting events, associated with intrusive-related hydrothermal systems. Repeated emplacement of high level dacitic porphyry bodies (Edie Porphyry; 2.4 - 3.8 Ma) was accompanied by a phreatomagmatic eruption which formed a diatreme-maar complex. Later hydrothermal fluids utilised permeable fault zones and diatreme contacts. Mineralisation took place during two main events. Stage I consists of early quartz - illite/sericite - carbonate phase with associated pyrite-arsenopyrite mineralisation. This phase is zoned from quartz - sericite-pyrite/arsenopyrite in the south at depth, to dominantly manganocarbonate - illitic clay - arsenopyrite- pyrite_s significant base metals in the north and at shallow levels. The majority of known gold (18.1 Mt @ 2.0 g/t Au) at Kerimenge is associated with Stage I activity. The gold occurs primary within the lattice of the sulphides and is metallurgically refractory. Fluid inclusion studies indicate early boiling and progressive cooling and dilution of hydrothermal fluids during the evolution of the Stage I event. Near paleosurface condensation of gases, which evolved off the boiling system at depth, produced abundant low pH bicarbonate fluids. During the waning phases of Stage I activity, these bicarbonate condensate fluids descended down permeable structures and formed banded manganocarbonate veins. High grade non-refractory gold mineralisation during Stage II event is restricted to favourable structures at relatively shallow levels and in the northern regions of the prospect area. Gold in this event exhibits a distinctive Au - Ag - Te -Cu geochemical signature, and is associated with hessite - tennantite - chalcopyrite mineralisation within quartz veining. Alteration and fluid inclusion studies indicate that this style of mineralisation is a result of the quenching of pulses of hot, late magmatic mineralised fluids by the cold condensate waters.

Jan 1, 1997

IN preparing a sample of refined lead for analysis, it is necessary to exercise great care to avoid contaminatien, as the amounts of the various impurities present in market lead are very small. The lead is cut into convenient-sized pieces, which are flattened out with a hammer, so that, on putting tbe lead through the rolls, strips of about one inch in width and Ij32iu. in thickness are obtained. The hammer, anvil, and rolls should be carefully cleaned before use. The strips oflead are cut up into pieces of about one inch square. If the lead is roIled out very thin and cut up into small pieces there is considerable risk of the acid acting too violently and causing loss through frothing over. A blank assay on all the reagents used should becarried right through, along with the actual analysis of the lead. This is of the greatest importance, particularly with regard to the determination of such impurities as iron, sulphur, arsenic, and antimony.METHOD OF ANALYSISThe method of analysis is as follows: Take two lots of 600 gIm. each, place in a large beaker, add 2000 cc. distilled water and 750 cc. concentrated HNOs. Cover with a clock glass and warm on a hot asbestos plate until all action ceases. (If any white precipitate forms, filter off and examine for Sn and Sb.) Add 420 cc. H2S04 (1-1), and stir well while adding the acid: Allow PbS04 to settle, pour off the clear liquid into a 12-in. porcelain evaporating dish, and start evaporating down, the dish being placed directly on an 8-in. ring gas burner. Wash the precipitate three times by decantation using approximately 1200 cc. hot water for each washing, and stir well...

Jan 1, 1922

It is well documented that drill and blast outcomes affect the downstream mining processes of loading, hauling, crushing and grinding but it can also significantly impact on mine profitability via dilution, recovery percentage, lump generation (iron ore), fines generation (coal, iron ore), coal loss and final wall stability. Drill and blast must therefore be optimised to improve the overall profitability via positively impacting on productivity and saleable product generation. It is however, difficult to achieve this because of the complexity of the number of parameters that must be integrated and managed across the entire mine value chain, ie the concept of æMine to MillÆ. This paper highlights, via a simple case study, the need to have a mineÆs drill and blast system both in control (so that it is predictable to a high degree) and with minimal variability (so the design actually makes it into the field). This type of management control is essential prior to optimisation work being undertaken. The æTeam ApproachÆ is discussed to illustrate the methodology of achieving drill and blast optimisation. A case study is presented to illustrate the potential benefits of this approach which in this mine represented a 27 per cent reduction in powder factor with the downstream functions achieving higher productivity with the same or reduced maintenance costs. It is essential for Australian mineÆs to implement the appropriate management strategies and experienced personnel placement to ensure that their mineÆs drill and blast system is correctly managed to facilitate the optimisation of profit. Without this, the Australian mining sector will become increasingly uncompetitive.

Jan 1, 1999

By J Coombes

Within the mining industry there is a growing trend of placing inexperienced technical people into positions of responsibility beyond their readiness. Their responsibilities often include providing the fundamental basis for decision-making: the resource model or even the daily grade control estimates. Whilst software continues to make the processes more accessible, the thinking and rationale for selecting parameters still requires control rather than auto-piloting. Operators run these systems in virtual isolation, and have limited immediate access to experts. Beyond the stress of the professional burden are the increased risks to the mining operations and overall project success.While many experienced experts recall being thrown in the deep end, the relative isolation from experts coupled with the gravity of professional burden before readiness, is less familiar. Many recall in intimate detail the experts who gave them direction, assisted them along the way and even helped them claw out of inadvertent mistakes. Experienced professionals all have a responsibility to enable capability across the generations, to ease the burden and to mitigate the risks.This paper provides an outline of how mentoring as an on-the-job professional development process can be structured to more fully enable success of a mentoring program. Three examples complement the principles presented.CITATION:Coombes, J, 2012. Structuring meaningful mentoring, in Proceedings International Mine Management 2012, pp 15-22 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By B T. Qin, C Zhu, Y W. Jia, Y Lu, F L. Li, Q L. Shi

Air leakage through rock fractures in coal mining is a major cause of coal spontaneous combustion. In order to overcome the deficiency of the existing fire control technology and prevent coal spontaneous combustion by isolating coal from oxygen, the article proposes a novel technology of inorganic solidified foam (ISF) with high expansion to fill fractures effectively. ISF consists of fly ash, cement, setting accelerator, redispersible polymer powder, water and aqueous foam. For preparing homogeneous and stable ISF, a preparation system with a pore type foam generator, a mixer device installed with a hollow shaft and helical blades, air compressor, slush pump and monitoring instruments was developed, and the working principles of key devices were elucidated. Based on a series of experiments on the different ratios of each component material and technological parameters of the preparation system, ISF with a foam expansion ratio of 8~10 and dry density of 250–400 kg/m3 was prepared. The relationship between elastic compressive strength, modulus of elasticity and density was summarised. Based on the injection experiment for fracture of loose coal pile with high temperature, the characteristics of sealing air leakage, compressive strength, thermal insulation, flow and cooling of ISF in the fresh state were investigated, indicating that ISF can effectively cut off the air leakage and cover the coal sample to reduce the temperature in the earlier stage, and ISF can remain stable and not crack. The ISF was applied to Luwa coalmine to seal small coal pillar pressure fractures and loose coal fractures in goaf. After press-casting the ISF in Luwa coalmine, the pressure-difference of inner-outer increased, meaning the effect of external conditions on the pressure-difference decreased, showing that it could plug the air leakage effectively.CITATION:Qin, B T, Shi, Q L, Lu, Y, Zhu, C, Li, F L and Jia, Y W, 2015. The novel technology of inorganic solidified foam with high expansion for preventing coal spontaneous combustion, in Proceedings The Australian Mine Ventilation Conference, pp 121–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By R A. Pax

Heavy machinery such as AG and SAG mills generate a significant amount of noise due to the processes that are occurring inside them. From an environmental perspective, the level of noise generated is a significant occupational safety hazard. However from a technical perspective the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of the primary comminution tumbling mills. Traditionally, the use of perfect mixing has been assumed when modelling the operation of AG/SAG mills. If this were true then the acoustic emissions from AG/SAG mills would be uniform along the length of the mill. Experimentally this has been found not to be the case. From another perspective it should not be the case because of the different conditions existing at the feed end compared to the discharge end. This paper presents the results determined by non-contact acoustics and their analysis in terms of understanding of the mechanisms occurring inside a mill.

Aug 8, 2011

By B Oostendorp, R van der Merwe, P

In order to assess whether polysaccharide depressants are strongly or weakly and reversibly bound to the surface of talc, a series of experiments was conducted on New York talc in which the floatability of the talc in a microflotation cell was determined. The talc was conditioned in solutions of carboxymethyl cellulose (CMC) or guar gum in 10-2 ionic strength Ca(NO3)2 or Mg(NO3)2. The talc was then washed with four successive aliquots of water, or cation solution, to try to remove the polymer and the flotation response of the talc was assessed. CMCs of different charge (DS) were used to assess the effect of charge on the strength of bonding. The results show that CMC and guar gum could be removed to a large extent from the talc surface by washing with water (the floatability was restored), however very little could be removed from the surface by washing with cation solution. The higher charge CMC was easier to remove from the talc planes in the absence of cations than the lower charge CMC. Thus CMC bonding to talc has been shown to be irreversible or very slowly reversible only if cations are present, implying that cations are necessary to keep the polymer bound to the surface of the planes to effect depression. The presence of ions in solution also had the effect of maintaining surface coverage of the talc by guar gum.

Jan 1, 2005

By Andrews B. S

The sinter plant at the Sulphide Corporation's Cockle Creek works produces a feed for the company's Imperial Smelting Furnace. The feed contains lead and zinc oxides and all the fluxes necessary for furnace operation. The quality of this feed is a major factor in furnace performance and the considerable flexibility of operation possible at the sinter plant has been used in efforts to achieve optimum operating conditions.Operating data is processed daily and information gathered from this source has led to three of the four improvements described.These improvements have resulted from elimination of gas recirculation, reduction of sinter returns sizing and alteration of ignition conditions and main layer fuel loading.

Jan 1, 1964

By Vink L, Johnson N. W, Mackenzie J, Young M. F, Johnston M, Landmark V

The influence of ore textures on metallurgical behaviour is poorly understood for most ores. An alternative method for characterising ore textures and for determining the resulting implications on ore processing has been developed for the Geor

Jan 1, 1998

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

By R T. A MacGillivray, S B. Curtis

Bacteriophage (phage) are viruses that infect bacteria. Protein coatings on the surface of the phage particle can be genetically engineered so that they bind to inorganic molecules. The filamentous phage particle is about 930 nanometres in length and 6.5 nanometres in diameter and consists of a single-stranded molecule of DNA surrounded by five different coat protein molecules denoted P3, P6, P7, P8 and P9. Peptide sequences in the P3 coat protein that bind to sphalerite and chalcopyrite have been identified. The binding is selective; phage with specific P3 peptide sequences bind to minerals but do not bind to silica or to pyrite. Two peptide sequences in the P8 coat protein that bind selectively to chalcopyrite and pyrite have also been identified. The amino acids in the P8 binding sequences are hydrophilic and thus a coating of a mineral particle with phage having these peptide sequences may render the particle hydrophilic. Experiments are underway to confirm this. Phage are relatively easy to grow and are not living organisms requiring an energy source to maintain life. Phage can also tolerate a range of pH and temperatures. Given this, and the ability to indentify phage coat proteins that bind selectively to a variety of inorganic molecules, phage have the potential to be useful tools in mineral processing and waste treatment.

Jan 1, 2008

By I KylmSkorpi, H Mansikkaviita

The traditional direct-heated drying process has been replaced by the steam drying process in non-ferrous metal smelters, where steam is available from waste heat boilers. Many recent projects have selected Kumera Steam Dryers in equipping a new production line or modifying an old production line. The industrial performance of the steam dryers has shown significant energy saving and emission reduction. The steam dryers have been operated at high availability and long maintenance interval. As the process principle of Kumera Steam Dryer is different from other equipment, the set-up for steam dryer plants is configured to fit the smelter site and operation conditions to achieve optimal performance. This article discusses the equipment involved in the steam drying process and their combination options.

Jan 1, 2008

By C Torrisi, J Andreatidis, M Duffy

BHPÆs Cannington process plant was commissioned in October 1997. The Cannington ore contains high grades of silver, lead and zinc but also contains high levels of fluorine which must be removed to produce a marketable concentrate. As a consequence the plant is more complex than the typical base metal concentrator. Some of the features of the Cannington operation include a single stage autogenous mill, multiple stages of flotation cleaning, two leach circuits, pressure filtration and a paste fill plant. The start-up and achievement of design performance for new lead/zinc operations has traditionally taken much longer than for gold or copper operation and is littered with many tales of woe with feasibility targets often not achieved (Agarwal, Brown and Katrak, 1984; Bulatovic and Wyslouzil, 1999; Leung, Andreatidis, Woodall and Alford, 1996; Sherman, 1999; Ward, 1998).

Jan 1, 2000