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By S N. Nyoni, K C. Corin, C T. O’Connor

Considering future water scenarios, as influenced by the increasing scarcity of water and the move towards sustainable process engineering etc, the closed water circuit becomes an important point of study in metallurgical operations, such as in milling and flotation. However, a deterrent in the use of recycled process water is often a lack of understanding of the effects of the accumulation of dissolved ions and other process chemicals. Recovery of the valuable minerals may be impacted by the concomitant complex mineral-pulp chemistry interactions. Literature indicates that these interactions are not necessarily antagonistic to process outcomes. Wet milling using steel media results in the dissolution of Fe from the media, the rate of which is dependent, inter alia, on the type of media and the chemical conditions of the aqueous environment in the mill. The pulp-phase interactions of dissolved ions with sulfide minerals may result in significant changes to the chemical conditions in the mill, which may subsequently impact negatively on the flotation recoveries. To understand the effect of these interactions in the context of the processing of sulfide minerals, this study seeks to consider the effect of three factors, viz mineral type – pyrite (Py) and galena (Gn) -, milling media of different compositions – forged steel (FS), 21 per cent high chrome and ceramic media -, and water chemistry, viz, deionised water (DI) and synthetic plant water (SPW). Ceramic media and galena are used for the respective control cases where the milling media and sulfide mineral contribute no Fe species. Using DI as a control case, a high ionic strength case is used to mimic the changes in water chemistry for a closed water circuit. Batch flotation tests are used as a diagnostic tool to determine the effects of these media-water-mineral interactions to investigate correlations between the chemical reactions occurring and chemical species present during the milling process and the ultimate flotation performance.

Aug 24, 2022

By R J. Longbottom

In this study the bonding within reduced titanomagnetite-coal compacts was investigated. The aim of the study was to better understand the binding mechanisms in the reduced compacts and, based on this understanding, to improve on their strength.Titanomagnetite ore was combined with sub-bituminous coal to form compacts. The compacts were then reduced by heating in a thermogravimetric furnace (TGA) to temperatures between 1000 - 1300°C under argon. The reaction progress was monitored by measuring the weight loss with time. The reduced compacts were found to have low strength in compression testing. The main form of bonding between the reduced titanomagnetite particles in the compact was by the formation of a slag-like material. Increasing the fi nal reduction temperature was found to have a profound effect on the strength of the compacts by promoting the formation of this slag-like material.Attempts to improve the strength of the compacts were made by changing two variables, the type of coal and the addition of rice husks. The addition of coking coal gave reacted samples that had little strength, while the addition of rice husks may have enhanced the strength of the reduced compacts.

Jul 11, 2011

By J Jackson, M F. Young

"Ore is the economic portion of a mineral deposit that can be extracted economically. Hence an ore type is a classification of the ore based on one or more dominant characteristics in order to enable communication between unit operations and/or technical disciplines.In project evaluation, ore types are often defined early based on geological observations by geologists and initial metallurgical testing is based around this classification even though a number of processing options can be under evaluation. However, the geological drivers of performance for each of these processes can be very different and the ore type classification for one process may not be relevant for another. In operations an ore type, as either defined in the project evaluation phase or those that evolve with additional knowledge, is unlikely to provide the knowledge required across all the unit operations. The ore type has a meaning to someone but does not necessarily for all unit operations across the value chain.Geometallurgical or orebody knowledge has evolved through the consideration of multiple processes within the value chain, the improved understanding of variability of process performance within ore types and the effect on the complexity of the mineral extraction processes. Furthermore orebody knowledge has been moving from personal based knowledge and understanding to a more process oriented approach where measurement and spatial and process performance modelling is playing a greater role. Advances in mine planning and scheduling allow for both detailed analysis of the block model and the expected extraction processing attributes across various time scales. This capability of analysing and describing the complexity still requires to be communicated to the various unit operations, which may be beyond the traditional classification of an ore type.The limitations of an ore type and potential alternatives to enable the relevant information to be communicated to the relevant groups are outlined through a number of case examples across the value chain.CITATION:Jackson, J and Young, M F, 2016. Ore Type – Everything to Someone but Nothing to Anyone, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 267–274 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By S Raval

The estimation of greenhouse gas emissions from coalmines is increasingly becoming a priority for both operators and regulators. At the same time, involved scientific challenges in the methane measurements is generating significant interest from global research community. Various technology providers are also actively engaged in improving their sensors and platforms to address the measurement challenges and capitalise the market opportunities. This presentation highlights rapidly evolving multifaceted landscape of coalmine greenhouse gas emissions. It covers the advances in sensors for the detections, including ground-based, airborne, and satellite-based systems as well as models for the emission estimations, including attempts to reduce the involved uncertainties.

Sep 1, 2024

By Payne AR

The high cost of gateroad repairs and maintenance in U.K. longwall coalmining is a clear indication of the failure of permanent support systems to fulfill their prime function, i.e. control of strata movement. The main component of gateroad support is the pack, the design and materials of which have experienced an important development process during the last 10-15 years. More recently, research investigators have attempted to give a design basis to pack quality and dimension, and reference is made to two theoretical approaches. In the course of a current research programme based upon in situ monitoring, interim design recommendations have been proposed as a means of effecting improvement in support efficiency. Identification of characteristic deformation behaviour forms the basis of the recommendations made and the subsequent improvement in gateroad performance reported.

Jan 1, 1986

By S Zummar, A Van den Bulck, T De Staercke, T Van Rompaey

An increase of 22 per cent in lead usage is expected in the European Union by 2050. During lead refining, the Harris process is a critical step in which a salt melt is used to remove arsenic, tin and antimony. During this process, the caustic salt melt absorbs these impurities, requiring regular evacuation before saturation. Current metallurgical practices for: 1) determining the end point of the lead alloy involve time-consuming sampling and offline analysis, and 2) determining the end point of the caustic salt melt are based on subjective visual observations by the operator. In the context of Industry 4.0 concept, automating these processes becomes desirable, as smart sensors systematically collect real-time data in an unbiased manner. This research focuses on monitoring the Harris refining process using objective methodologies. Two different methodologies are investigated. The first methodology focuses on electrical conductivity changes of the caustic salt melt as function of Sb content. For this study, synthetic and industrial samples are used. A lab-scale electrical conductivity set-up was built to accommodate the aggressiveness of the salt melt. Initial findings suggest a promising relationship between electrical conductivity and Sb content in the caustic salt melt. Although the results are preliminary, the study provides valuable insights by enabling real-time measurements. The second methodology focuses on measuring the electromotive force (EMF) in lead doped with Sb at pilot-scale. Multiple probes are reevaluated for their effectiveness in Sb measurement. Ultimately, a partially stabilised MgO probe with Ni as a reference, without cardboard and copper protection caps, yields promising results. A correlation between EMF and Sb content is observed. However, repeatability issues arise due to possible wire interference at low temperatures. The results underscore the potential of advanced measurement techniques in optimising lead alloy production within the context of Industry 4.0.

Aug 21, 2024

Mining of the silver-lead-zinc orebodies at the George Fisher Mine officially started in 2000. A review of mining performance to date shows that many of the extracted primary stopes have experienced some degree of hangingwall dilution. The degree of hangingwall failure in the stopes became progressively more extensive throughout mining of the orebodies in 2001 and 2002, culminating in the unplanned catastrophic failure of the 744D stope in which the ore between 13C (2683RL) and 12L (2714RL) sublevels caved into the previously mined cavity between 13L (2654RL) and 13C sublevels. This was followed several months later by another unplanned caving event in a nearby stope, 740D. As a direct result of these unplanned failures it was decided to mine the stopes with a smaller span than had been previously planned and in a primary-secondary pyramidal stoping sequence. To limit the exposure of the stope hangingwall, a hangingwall drive is no longer developed and therefore geologists no longer have access to the detailed geological information that this provided. Geologists at George Fisher Mine have had to be adaptable and flexible in response to these proposed changes and rely more on data from drilling than mapping for their geological interpretation. The result is that the drilling cycle has become much more critical in the planning process.

Jan 1, 2003

By R Brown

The Singapore Land Transport Authority Contract C917A is for the design, construction and completion of all outstanding works under the original Contract 917, including taking over the design and construction responsibility for the works carried out by previous contractor. Construction works connect the bored tunnels between the stations at King Albert Park and Sixth Avenue on the Downtown Line two in Singapore.The original contractor became insolvent leaving the works incomplete. On 29 August 2013 McConnell Dowell were awarded the completion contract following a fast-tracked tender process. The completion contract required a quick start and therefore the recruitment of some of the original workforce. A large majority of the original workforce was from Malaysia, Indonesia, China, Philippines, Bangladesh, India and Thailand. In order to ensure that the safety standards were upheld, and that the new workforce embraced a safety culture, a behaviour based safety (BBS) approach was implemented.The BBS approach was implemented to overcome the existing poor cultural safety behaviours, and to ensure that high standards and expectations for safety were implemented. This ensured that the workforce were comfortable in identifying hazards, avoiding shortcuts, and changing poor safety behaviours.This article outlines how a BBS program was delivered on the C917A project, containing defined goals, communication tools, and assessment and feedback models.CITATION:Brown, R, 2014. Behaviour-based safety with a foreign-based workforce, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 65–68 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By P M. Dight

Shotcrete usage in declines and developments has become pervasive as operators strive to achieve production improvements. Issues of mix control, fibreload, thickness control, temperature and curing conditions all play a part in the quality control. Often to overcome some of the quality control issues designers over specify the strength requirements in order to meet their operational constraints. Adherence to the standard civil testing requirements of 28 days moist cured at 21ºC without properly calibrating these results to the changing environment underground leads to contractual disputes. There are a number of standard tests specified including cylinder tests, cored tests, beam tests and round determinate panel (RDP) panel tests. The logistics of storing these samples and then transporting them to concrete testing laboratories without due regard to temperature changes with time can influence the results. All the samples can be readily handled by personnel except the RDP panel. The standard RDP panel is 800 mm diameter by 75 mm thick and requires an ITH machine at the mine and a fork lift at the laboratory to move it around. This paper will examine the possibility of a panel which provides scalable results to the standard RDP panel but can be easily handled by personnel and/or tested on site with suitable equipment. This allows for faster turn around and better quality control for the sample prior to testing. This enhances the identification of quality control issues at the mine and improves safety.

Mar 21, 2011

By S Brochot, M-V Durance

In many cases, current metallurgical accounting practice does not consider the errors associated with the measurements used in obtaining the metal balance. Considering all measurement errors, including errors associated at each step of the process - from sampling and analytical errors to measurement errors in circuit instrumentation, can improve the accuracy of the final metal balance - assisting in the improvement of process performance, optimisation and control.The consequences of the inclusion of measurement errors on metal balance for different circuit configurations and typical metallurgical accounting practice (two product and three product formulae) will be discussed in this paper.Examples of the tools, methodology of implementation, and periodical metal balance tasks are presented to illustrate the advantage of this approach in meeting the different requirements of each department.CITATION:Brochot, S and Durance, M-V, 2012. A new approach to metallurgical accounting, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 217-224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Kentwell D. J, Cusak C. J, Harvey-Kelly F. E L, M D. Goodz

The Morning Star Gold Mine presents an example of a prolific operation with considerable historical records, mine workings, drill hole logs and countless plans from greater than 20 adjacent mines which have now been consolidated to form the current project. Implementation of 3D computer modelling in the planning stages has provided an additional tool to integrate and refine geological models as a guide to some exploration strategies. It has allowed for a re- interpretation of the host rock units, dimensional constraints, new exploration extensions and provisional resource modelling. The initial consideration of this project was to integrate 135 years of mining history into a single database. Each historic mining area had an unrelated mine grid, often established parallel to the long axis of their main stopes; some were based on magnetic or true north. Survey plans were in chain, imperial or metric units. Through the manipulation and rotation of old grids, previously unrelated mine workings began to form continuous mineralised zones, with unmined portions still remaining in between the existing development. Furthermore the current drillhole database of >433 holes showed numerous confirmatory intersections of new mineralisation. A series of tiered tables were created within a relational database to derive guidelines for assessing data to attribute a Mineral Prospectivity Value [MPV] based on key indicators of mineralisation. Indicator logging now forms the basis of geological descriptions.

Jan 1, 1997

By D R. Wines

The design of near-surface civil infrastructure requires detailed consideration of the geological/ geotechnical conditions, excavation geometry and sequence and ground support measures to ensure stability of the underground openings and minimal impact on overlying or adjacent infrastructure. Twin parallel road tunnels have been designed and built with connecting cross passages and a piggyback busway tunnel as part of a large infrastructure project in Australia. The tunnels were excavated in poor to fair quality rocks using road headers. Temporary ground support includes shotcrete, rock bolts and canopy tubes. Extensive numerical analyses have been performed to analyse the expected behaviour of the tunnels during excavation, including two-dimensional analyses using UDEC and three-dimensional analyses using FLAC3D. Structural defects in the rock are explicitly included in the 2D analyses to examine the potential for localised ground instability. The stress redistribution is captured by the 3D modelling with an accurate representation of the complex excavation geometry and the detailed excavation and support sequence. This paper presents the modelling methodology, numerical results and discussions on integrating both 2D and 3D analyses to achieve reasonable design.

Mar 8, 2011

Esso-BHP have installed a Production Supervisory Control System that is presently controlling the offshore oil and gas facilities on the Barracouta and Marlin platforms from an onshore master station. This control is achieved with a computerized master station onshore which uses a UHF radio system for telemetry and control. The system is designed to control, monitor, and gather data from a large number of oil and gas production platforms and has flexability to handle future variations in operating conditions. Thn -etom ..ill kn nvt,,ndnd to thn I-lalihn+ rJ,+f, rr , Into +hie -- -A +n the lei...,fieh .,lo+fnrmc A.,;- 1071

Jan 1, 1970

By G Capes

A novel open stope design approach is presented that delivered improved performance in a mining area with poor ground conditions at the Olympic Dam mine. During 2019, a large open stope had an unplanned caving event resulting in the inability to extract the planned tonnes and subsequent sterilisation of nearby stopes. A design limitation was the lack of data and understanding around the alteration domain extents, the rock mass strength controls and limits, the failure modes controlling stope stability in the local area, and the use of conventional stope shapes. From the available data and failure observations, it was inferred that the dominant caving failure mode resulted from a blocky rock mass impacted by structure and alteration causing an unravelling failure mechanism. Numerical and empirical analyses were conducted to test this hypothesis and establish strength limits for design. The strength limits for the design were then used to provide a range of outcomes from which future stope design shapes such as chamfered backs could be selected. Three alternate chamfered geometries were selected to trial the innovative designs. The application of this methodology in 2020 resulted in overbreak reduction from >100 per cent in the initial caved stope to

Mar 29, 2023

By P B. Schwann

The commonly accepted genetic theories of Pilbara iron ores and Woodie Woodie manganese ores have often presented them as quite unique. This apparent uniqueness is not confined to just iron and manganese, but is also seen in gold and copper deposits in Western Australia. The published material on iron and manganese ores would seem to have either a quite complicated genesis or none at all. An alternate theory for the origin of these deposits is presented which involves a protore with simple oxidation and pH controls with hydrothermal fluid sources from the diagenesis and dewatering of the underlying strata. This theory explains the distribution, thinning, cold dolerites and very high concentrations of deleterious minerals observed in these deposits. This genesis system is also related to the systems that deposit hydrothermal gold and copper in sediments in the region.This paper presents the author’s observations, sampling and mapping after several decades studying and exploring for the minerals in Australia and locations overseas. All of these theories were developed with (or in spite of!) the guidance of Mal Kneeshaw, but would never have seen the light of day without him and the others presenting here. It is not what I would call scientifically polished, and possibly deserves more detailed studies; it is, however, presented as a discussion paper.CITATION:Schwann, P B, 2015. Related genesis for iron, manganese and gold-copper ores in Western Australia, in Proceedings Iron Ore 2015, pp 327–336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M J. Nugus

The Geita gold mines in north-western Tanzania have produced 5 Moz of gold from an estimated endowment of 15 Moz. They are generally classified as typical Archaean orogenic banded iron formations (BIF)-hosted gold deposits in banded iron formations as described by Goldfarb, Groves and Gardoll (2001); Neall and Phillips (1987); Phillips and Powell (1993) and Neall (1987). The controls on gold mineralisation have been reassessed to conclude that Nyankanga, and we conclude that Nyankanga, the largest deposits within the group, developed during a dynamic and protracted deformation history intimately associated with several stages of hydrothermal fluid flow and alteration. The fluid-induced fractures associated with gold mineralisation are primarily manifested as submillimetre to metre-scale fractures and breccias developed preferentially in rocks that have been previously deformed and altered by silicification or seafloor metasomatism. This realisation detracts from the exploration and mining strategies that would solely concentrate on fluid pathways and associated wallrock alteration and veining solely within the BIFs as hosts for economic gold mineralisation.

Aug 22, 2011

By S H. Algie, E J. Knoblauch, I A. Lovatt, S G. Doig

Mill operating teams are expected to engage in a perpetual quest for process improvement – pushing the boundaries of practical process limits and testing new technology to achieve the next step-change in plant performance. Often the barrier to improvement lies in gaining management approval for process changes.Getting approval for investment in novel technology carries an added degree of difficulty, particularly in risk-averse operations, when it challenges conventional wisdom. A case in point is a new technology for controlling variability in slurry distribution. There is a widely held view that less-than-specified classification efficiency and spraying and roping of individual units in a hydrocyclone cluster, must be accepted as unavoidable. That these are wholly correctable deficiencies resulting from unequal loading of the individual units seems a bold claim. Wouldn’t the high turbulence of pumped slurries overcome all potential for segregation of solids? This paper discusses how the task of developing confidence in a new technology can be approached by a combination of physical modelling at small scale, and full-scale operating experience. Proving efficacy then leads to the next task: demonstrating value. Again, the particular technology serves as an example that could be of value to others developing relatively low-cost technologies. A high-pay-off as an investment may be achieved with improvements in metallurgical performance that are small in relation to normal process variations. This has led to an exploration of how process simulation modelling could be used, in conjunction with production data, to provide a benchmark for the expected change, which could be expressed in monetary terms.The next goal, which is currently being achieved in operating plants, is to realise the greater value now available through the optimisation of cyclone configuration, which becomes practical when the confounding effects of cluster instability are removed through equal loading.CITATION:Doig, S G, Algie, S H, Lovatt, I A and Knoblauch, E J, 2018. Investing in new process improvement technology: reducing the risk of implementation – a way forward, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By M Suzuki

Although several models for the surface tension of molten oxide slag have been proposed, suitably accurate predictions of this property are not yet possible. The surface tension, or surface excess free energy, of molten oxides is largely determined by the ionic coordination induced by surface relaxation. However, the associated mechanism of surface structural relaxation for molten oxide mixtures such as slag is complex and not yet fully understood. To allow a better evaluation of surface relaxation characteristics, the present work analysed the ionic coordination associated with the surface-relaxed states of several oxide mixtures. This work especially focused on calcium aluminate slags because these materials exhibit complex relationships between composition and surface tension. The effects of incorporating low concentrations of SiO2 as a surface active component on the surface ionic coordination were also examined. X-ray absorption techniques were used to assess oxygen and cationic elements in glassy samples after surface relaxation treatments, and molecular dynamics simulations based on a polarisable ion model of molten slag with vacuum/melt interfaces were also performed. The X-ray absorption techniques provided data related to electron yields (which are primarily associated with surface features) and fluorescence yields (which evaluate the bulk material). Thus, the ionic coordination characteristics of both regions were investigated. The results of molecular dynamics calculations allowed statistical analysis of the distributions of Al- or Sicentred polymorphs as well as the bond angles between cations and oxygen anions in the vacuumexposed and bulk regions in the equilibrated melt. The results indicated that bridging oxygen ions were preferentially distributed in the relaxed surface region rather than non-bridging oxygens. These bridging oxygen ions represented vertex connections between AlO4 or SiO4 tetrahedra. In the case of the calcium aluminate slags, the addition of one Ca2+ ion as charge compensation for two Al3+ ions was found to be necessary to form two AlO4 tetrahedra. This specific feature of surface ionic coordination could be responsible for the complex trends observed in surface tension data. The incorporation of low concentrations of SiO2 reduced the proportion of tetrahedrally-coordinated Al ions such that higher coordination states become dominant in the bulk of the material, whereas AlO4 tetrahedra were preferentially distributed in the surface region. SiO4 tetrahedra were the preferred Si-centred polymorph and were likely connected to one another to form bridging oxygen ions at the surface. On the basis of these results, a model to predict slag surface tension was proposed, and the energy of the formation of the ionic clusters resulting from surface relaxation was taken into account.

Aug 21, 2024

By F Baars, M Zu, C A. RosiFre, L Lobato

A genetic model for the genesis of high-grade (>65 wt per cent Fe) Proterozoic, banded iron formation (BIF)-related iron deposits such as the Tom Price, Mount Whaleback deposits in the Hamersley Province (Australia), the N4E, N4W, N5 deposits at Carajßs (Brazil), the Aguas Claras, Conceitpo, and Casa de Pedra deposits in the Iron Quadrangle (Brazil), the Donkerpoort West, Kwagas East deposit in the Thabazimbi iron ore district (South Africa), or the Saksagan ore field at Krivoy Rog (Ukraine), needs to take into account the: timing of regional metamorphism with respect to the upgrade of BIF to high-grade iron ore; significance and relationship of the proto-ore to the hydrothermal alteration minerals and zonation and the process of iron enrichment; source and oxidation state of the hydrothermal fluids that caused the iron enrichment; types of geochemical processes that caused the hydrothermal alteration and iron enrichment; and significance of the widespread carbonatisation of the host rocks as a prerequisite for high-grade BIF-related iron mineralisation.We argue that a unifying model for high-grade BIF-related iron deposits cannot, presently, adequately explain the geological and geochemical characteristics observed in these deposits and, therefore, provide two end-member models that take into account the diversity of geological and geochemical ore deposit features. Our discrete model for the genesis of high-grade, BIF-related iron deposits is based on the interpreted tectonic setting, distinct hydrothermal fluid source of, and processes observed in, major BIF-related iron deposits. We divide two end-members: Proterozoic deep fault-magmatic (Carajßs) type, and Proterozoic rift-basin (Hamersley) type.Both end-members experienced varying degrees of deep weathering episodes that effected the hypogene enrichment and, ultimately, yielded the high-grade iron ore mined in many places today.

Jan 1, 2005

By G M. Mudd

Mine tailings represent one of the two largest sources of mine waste from the minerals industries (the other being waste rock). Given the problems of declining ore grades and growing production, tailings generation is increasing exponentially across the global mining industry. Common practice is for mines to build large containment dams to store tailings during operations, which are then rehabilitated following mine closure. At some sites, however, the controversial practices of riverine or marine dumping of tailings is still practiced. As recent tailings dam failures have shown, there are legitimate questions being raised about the long-term viability of leaving tailings above ground due to the risks of collapse and failure. At present, it is rare for mines to emplace tailings back into former mine voids following mine closure, most commonly into a former open pit mine void (although a fraction of the tailings may be used for underground mine backfill, this is minor in scale). The approach of in-pit tailings has numerous advantages, such as inherent physical stability, low to negligible acid and metalliferous drainage (AMD) risks, as well as allowing more productive use of formerly mined land. In tropical areas where surface repositories are prone to leakage with potential for AMD and widespread dispersal of radionuclides (in the case of uranium mining), in-pit management provides particularly strong advantages – thorough hydrogeological studies are required, however, to address residual groundwater contamination risks and to establish sound, long-term environmental monitoring regimes for groundwater quality and subsidence issues. This paper presents a study of in-pit tailings management and compares it with surface repositories established in a tropical climate. The comparisons lead to the conclusion that, at least under tropical conditions, in-pit tailings management should be considered as world’s best practice – especially for radioactive uranium tailings.

Aug 8, 2011