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By M I. Pownceby, A Guiraud, S Purohit

Sticking and breakage of iron ore pellets during high temperature reduction can result in several operational challenges during shaft furnace ironmaking. With the shift to H2-based DRI processes and decreasing iron ore quality, this issue becomes more prominent. It is therefore important to understand how the iron ore chemistry and mineralogy affects the sticking and breakage of pellets inside the shaft furnace. This study provides a review of the mechanisms that lead to sticking and breakage of pellets inside the shaft furnace. The sticking index of pellets is related to the rate of metallic iron production as well as the precipitation morphology of product iron. Sticking of pellets is also enhanced by the formation of low-melting slag phases. The breakage of pellets inside the shaft furnace is often associated with the mechanical load of burden and pellet swelling, which is caused due to iron whisker or protruded iron formation. This paper investigates how the composition of iron ore, particularly the presence of different impurity oxides such as SiO2, Al2O3, MgO, CaO and alkali oxides in the pellets, influences the sticking and swelling indices. The effect of ore mineralogy on these adverse behaviours is also discussed.

Sep 18, 2023

By T G. Vizcarra, B Wong

Optimisation projects are regularly undertaken without knowing the root cause of an issue. It is all well and good to trial a multitude of flotation reagents, change the operating characteristics of your flotation cells, or add more media into your ball mills, but time and again, root cause analysis traces issues back to the performance of hydrocyclones. In JKTech's experience, hydrocyclones are poorly operated and maintained (in both primary grinding and regrind circuits), exacerbating issues that many operations commonly experience.Recent case studies are presented where JKTech has been engaged to improve the process only to discover that the hydrocyclones were the main issue. At one operation it was found that the hydrocyclone feed density gauge was reading significantly lower to the actual density. Following re-calibration of the gauge, and with further improvement of cyclone operational and design parameters using JKSimMet, a significantly sharper efficiency curve was achieved. This resulted in improvements to downstream recoveries while alleviating pumping capacities that were previously constrained by fines and water caught up in recirculating loads.Several other case studies are presented which may seem to be relatively basic, but many basics seem to be getting lost in the day-to-day responsibilities of the modern plant metallurgist. Simple fixes to hydrocyclones can result in significant production increases, but more focus is needed in monitoring these to sustain the benefits.CITATION:Wong, B and Vizcarra, T G, 2018. What category cyclone is devastating your plant?, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 665–673 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By P F. Knights, P Boniwell

This paper investigates the causes of low effective utilisation of the production drill fleet at the Telfer Underground Gold Mine, as measured by the percussion hours per shift. The first part of this paper focuses on a site time and motion study conducted to accurately identify shift time allocation and optimal drilling parameters (manual versus automatic, and suitable flushing mediums for varying ground conditions) as well as quantifying the business potential for automated or remotely operated production drilling. The second part of the paper focuses on the rate of successful hole completion for automated production drilling during shift changes. Two main areas of drill optimisation were identified. Firstly, a site-specific drilling procedure was established so as to ensure that all operators were drilling using optimal parameters. Total production metres per rig increased by 10.7 per cent as a result of the implementation of this standard. It was observed that a 25 per cent faster overall drill cycle was achieved using air mist flushing, and that manual drilling achieves a 19 per cent faster overall drilling cycle in comparison to automated drilling. Secondly, routine provision to the maintenance department of automation reliability reports that outlined the principal causes of unsuccessful hole completion led to an increase in production metres of a further 4.1 per cent, measured between January 2007 and August 2007. First hole automation reliability increased from 39 per cent to over 77 per cent over the same time period. Second hole automation completion was increased to 74 per cent, leading to a higher proportion of production achieved through automated technologies.

Jan 1, 2008

By S F. Rogers, K Doumis, J H. Graaf, B J. Barsanti

Advances in technology now allow geotechnical practitioners to better describe the properties and variability of a rock mass through advances in surface and underground mapping, borehole technology and geophysical imaging. Yet the way in which practitioners use this data is not being realised to its full potential and the quality and quantity of data that is collected is often superior to the conventional design approaches that are typically adopted. A discrete fracture network (DFN) approach provides the ideal basis for using this data to generate geologically-realistic rock mass models based on parameters derived from field data, which more effectively capture the variability and rock mass behaviour. However, until recently, the DFN approach has mainly been applied to cave mining and small-scale models associated with synthetic rock mass modelling or groundwater flow modelling for the nuclear waste and oil and gas industries.Ground support design for blocky rock masses in Australia is often dealt with in a rather traditional manner, adopting either an observational empirical approach through rock mass classification systems or conventional wedge stability analysis techniques. Using these methods requires several generalised assumptions about the rock mass fabric and excavation geometry. As such, the support system is often designed for a worst-case scenario based on a predetermined risk tolerance that the mine is willing to accept and a design block size that is generally determined by the proposed excavation dimension.A study by Doumis (2014) used conventional wedge stability analysis and the probabilistic key block analysis software JBlock (Esterhuizen, 1996) to estimate potential block sizes and support requirements. A DFN approach has also been adopted at Callie underground mine using FracMan™ software (Golder Associates, 2014). The methodology of the DFN wedge analysis will be compared with the key block analysis work undertaken by Doumis.CITATION:Graaf, J H, Barsanti, B J, Doumis, K and Rogers, S F, 2014. Towards the implementation of discrete fracture network modelling as a geotechnical design tool – case study of callie underground mine, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 399–408 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By G M. Jeffress, D C. Arne

There are two discrete aspects to collecting portable X-ray fluorescence (pXRF) data to obtain reliable results and to comply with reporting requirements under the 2012 edition of the JORC Code (JORC, 2012) – sampling method and quality assurance. A robust sampling program is required to obtain representative material for analysis. The appropriate method should be established for a particular project using a small orientation study. A variety of approaches to sampling soils, drill cuttings, rock faces and diamond drill core are discussed. These include using multiple spot analyses, scanning using a single operating beam and the collection of cutting saw pulps. The operator must also be aware of the attenuating effects of analysing through sample bags of different material types for various elements as well as the limitations of current pXRF instruments in reporting reliable data for certain elements. The analysis of the samples must also be accompanied by a quality assurance program in order to generate data that are ‘fit for purpose’. This includes recording X-ray tube resolution on a routine basis, using matrix-appropriate standards for which total elemental concentrations are available, using silica blanks, capturing sufficient duplicate analyses to constrain data precision and obtaining check assays to calibrate pXRF data against laboratory data. Examples of quality control approaches and data are presented. Table 1 of the 2012 JORC Code also recommends that information on instrument make and model, reading times and calibration be provided in any reporting of pXRF data. To this should be added information on operating mode and temperature, software version and moisture content of the samples. A robust sampling methodology with a suitable quality assurance/quality control program should produce pXRF data of sufficient quality for public reporting purposes, provided that the data are presented using appropriate cautionary language and adequate supporting information.CITATION:Arne, D C and Jeffress, G M, 2014. Sampling and analysis for public reporting of portable x-ray fluorescence data under the 2012 edition of the JORC Code, in Proceedings Sampling 2014 , pp 57–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By G P. S Resende, D E. G Oliveira, E A. S Baeta, T F. Bravin

There is currently in the mining industry, as well as in other industries, a movement seeking to increase investments in decarbonisation processes to help combat global warming. Among some initiatives taken is replacing diesel-powered mobile equipment in the mines with electricity-powered equipment, such as electric off-highway trucks or even belt conveyors in the mining operation. Samarco is a Brazilian mining company that since its conception has used a conveyor belt mining system in its mining operation, using only a small number of trucks to complement the mining process. This mining process that combines conveyor belts and trucks has brought environmental gains for the company since the environmental impact of conventional truck-only mining is greater than that of the combined system. To measure these gains, a medium-term mining plan was developed in which two fleet scenarios were detailed. One scenario contemplated a high level of detail of belt mining seeking its maximisation, while the other considered the operation performed 100 per cent by trucks, eliminating the use of conveyor belts. Through the comparison of these two scenarios, it was possible to make an inventory of atmospheric emissions and greenhouse gases for each one of them considering data such as types of equipment, diesel consumption, total distance travelled and energy consumption. The results showed that the fleet scenario with conveyor belts results in periods with up to 15 per cent less greenhouse gas emissions and 37 per cent less total particulates compared with the truck-only scenario. Therefore, the results confirm the environmental benefits of the method and the need to look for ways to even expand it in future operations through a study to identify the potential areas in the long-term mining plan.

Sep 18, 2023

Rosebery Mine is situated on the west coast of Tasmania and is AustraliaÆs largest volcanic-hosted base and precious metals deposit (zinc, lead, copper, gold and silver). The milling operation has been producing zinc, lead and copper concentrates continuously for over 100 years. RoseberyÆs long life demonstrates the operation to be high grade, and high margin, capable of operating through several commodity price cycles. Paradoxically, throughout this long history the ælife-of-mineÆ as defined by proven and probable reserves has been short. Zinifex has demonstrated its commitment to discover the future of Rosebery with the growth project æProject HorizonsÆ. The aim of the project is to extend the life of mine beyond 2020, with an additional exploration expenditure of $19 million over three years. Despite the maturity of the deposit, early success has confirmed the potential with the discovery of new resources. Mine planning strategic studies are challenging established paradigms of mine production, throughput rates and metal cut-off grades. Discovering the optimal process rate for Rosebery, by examining the æHill of ValueÆ and underground mine optimisation is proving critical to the best exploitation of RoseberyÆs rich resources. The promise of finding a mine within a mine is being realised, with new lenses being delivered by exploration success and real grade/tonnage options optimised through dynamic mine planning. The future of Rosebery is co-dependent on these two areas of discovery. This ensures capital expenditure decisions are informed, to secure the next 20 years of wealth creation and beyond.

Jan 1, 2008

By R Ayothiraman

Tunnel excavation may induce adverse effects on nearby existing structures/foundations in urban areas. Accurate prediction of tunnelling effects on pile foundations of nearby structures in the urban environment poses a major challenge during design. Several studies have been undertaken to understand the mechanisms of the soil-tunnel-pile interaction, which focused only on influence of tunnelling on nearby existing building and foundations. However, effect of pile loading on existing tunnels did not receive enough research attention so far. So it is essential to measure the response of existing tunnel-lining due to loading on newly constructed pile to assess to the safety against the additional forces/moment caused by pile loading and to evaluate the critical distance for the proposed construction of any structures from the tunnel location. This paper presents result of three-dimensional (3D) finite element analysis carried out in ABAQUS to investigate the effects of pile loading on existing tunnels embedded in cohesive soil. It is found that the effects on tunnel lining depend on horizontal separation distance between pile and tunnel as well as location/elevation of pile tip with respect to tunnel location.

Mar 8, 2011

During the life of a mining project in Papua New Guinea (PNG), the greatest impact is on the people of the project area and the most intense, day-to-day contact is between these people and the project's field staff. Yet formal structures at present emphasise contact between much higher levels of national government and company personnel. Whilst understandable, this is unfortunate particularly since, given the nature of PNG politics, villagers do have a powerful influence on project success, as recent dramatic events on Bougainville have indicated. A greater role for local views and greater attention to such views by other parties is clearly required. But to achieve a successful marriage between informal village politics and the formal structures of investment procedures will require considerable patience and adjustment. This should be reflected in the cost of project development and be regarded as being as of a significance equal to that currently accorded to the technical aspects of project development.

Jan 1, 1990

By W Assibey-Bonsu

The paper provides a brief review of the multivariate uniform conditioning and the localised multivariate uniform conditioning techniques and presents a case study based on a porphyry copper gold deposit in Peru. Two other important scenarios have been investigated and will be particularly emphasised: The recovered selective mining unit (SMU)s depend on a combination of copper and gold content, which can be expressed by means of ænet smelter returnsÆ (NSR). Two approaches are compared. Firstly, the application of a composite cut-off on NSR on the joint distribution of each grade and the application of uniform conditioning to three variables is investigated, ie for the first approach NSR is used as the main variable. The second approach considers copper as the main variable. In the case of multiple domains the procedure used to apply the technique to process mixed panels is clarified and recommendations are made.

Sep 26, 2011

By D C. Ford

The Argyle AK1 orebody was discovered in 1979 and subsequently found to be a large, economically viable reserve with high grade diamondiferous ore. Production began via an open pit operation at the end of 1985 and has continued for some 25 years to present day. This, however, will come to an end in the next few years with production moving to an underground operation via block-cave mining methods.A series of studies from 2001 - 2005 was carried out; diamond drilling commenced after approval in 2006, from an exploration drive to determine the likelihood of the current proposed block cave operation.In 2006, development of the block cave project began, in order to realise the part of the orebody below the extent of the open pit mining operation.Development of the block cave technique, comprising an undercut level beneath the target zone of the orebody with subsequent extraction level 15 - 20 m beneath, relies largely on a number of block-caving parameters (hydraulic radius, rock type, structure and orientation of stress and grade of the orebody). These all have an influence on cave ability and eventual profit of the operation. Evaluation of further potential for taking this orebody beyond the block cave phase with options such as sublevel-caving are being considered for the UG-2 portion of the resource/reserve. Diamond drilling for this work is currently under revise.The challenges faced in transitioning form the surface operations to the underground, comprising a changing workforce, converging development drives, underground aquifers, major excavations and transportation of ore via automation are intriguing.

Aug 22, 2011

By S Mitra, D O’Dea, N Barrett, T Honeyands, P Zulli

The steel industry continues to explore and demonstrate technologies that decrease its greenhouse gas emissions, especially in blast furnace ironmaking where alternate operating conditions will be required. As the furnace has been optimised over many years, it is approaching the minimum fuel rate possible with coke and Pulverised Coal Injection (PCI). Alternative operating conditions are therefore required to further decrease greenhouse gas emissions. Because of this, hydrogen has been proposed as a reducing agent in the blast furnace. Injection of hydrogen through the tuyeres was assessed using a comprehensive 2D blast furnace global model. The model was calibrated to a blast furnace operating with PCI as a base case and various approaches to hydrogen injection assessed, with a particular focus on displacing PCI. The maximum hydrogen injection rate of 19.5 kg H2 per tonne of hot metal was predicted, limited by decreases in the raceway adiabatic flame temperature and top gas temperature. Internal blast furnace conditions, such as gas composition and reduction degree were also predicted. Holistic analysis was performed to estimate the effectiveness of hydrogen injection on reduction of greenhouse gas emissions. Based on these results, the changes in blast furnace operation and emissions under hydrogen injection are discussed.

Nov 8, 2021

By A Murphy

Mining plants and infrastructure, and the decisions made by their designers, can have large impacts on their environmental and social context, commonly referred to as the site or plant footprint. They can also be the source of constructive contributions to sustainable development when designers are enabled via the information, systems and tools to incorporate sustainability in engineering processes. A facility’s footprint and the project’s contribution to sustainability – economic, environmental and social aspects – are now key considerations in regulatory approval processes and are the fundamental drivers of support, or opposition, from the project’s stakeholders.Historically, plant and infrastructure designers have not been well integrated with the environmental and social professionals who are engaged to pursue regulatory approvals. Despite this, many objectives central to technical and process engineering have in fact contributed positively to a facility’s footprint and indeed its contribution to sustainable development. Examples of these objectives include increasing process and energy efficiency, and minimising the quantities of waste requiring disposal. With the framework of sustainability, mining plant and infrastructure designers are indeed at the forefront of incorporating sustainability into resource industry projects and are central to the process of obtaining regulatory approvals and ongoing stakeholder support. The process of incorporation starts with a shared understanding of sustainability and sustainable development, and continues with project processes that facilitate information and knowledge exchange throughout the project life cycle.CITATION:Murphy, A, 2014. Incorporating sustainability into mining plant and infrastructure design, in Proceedings Life-of-Mine 2014 , pp 637–646 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

A hidden asset in most exploration and mining activities is data. Common practice involves the spending of large amounts of money to discover, define and prove the viability of a mining project. Some organisations have used operations research analysis and internal costing methods to allocate a value to their data and to compare the costs of data maintenance to other more tangible activities like plant and equipment maintenance. Those organisations, which do not undertake such an analysis often, have little knowledge or understanding of the extent and the worth of their data. Often the organisations lack of knowledge and understanding of the data is indicated by their failure to fully exploit or realise their opportunities. The focus of this paper is to discuss new technologies that optimise the management and security of collected and derived data. The technologies discussed are components of the software systems acQuire and MineSight.

Jan 1, 1999

By C MacRae, N Wilson

CSIRO Minerals has recently developed an electron microprobe (EMP) based imaging (or mapping) method for characterising ilmenite concentrates. The method requires an electron microprobe analyser to collect elemental X-ray maps which are then processed via an in-house developed software module (CHIMAGE). The type of information readily available from EMP mapping includes; primary phase identification, modal analysis of phases, chemical analysis of individual phases, textural information (eg the alteration stages in the formation of leucoxene or pseudorutile from primary ilmenite and the development of macro-porosity), and the identification of coatings or pore-fill material. All of these parameters will impact on the choice of future downstream processing options considered for any particular ilmenite concentrate. The method has been demonstrated to be a sensitive analytical tool for assessing the distribution of aluminosilicate minor impurities in ilmenite feedstocks from the West Coast of Australia and also for characterising the complex chrome-spinel gangue phases common in East Coast ilmenite concentrates from the Murray Basin.

Jan 1, 2001

A description of:1. Air-lock at No. 14 Upcast shaft.2. Pit-top gates at Dudley winding shaft.3. Safety rider employed in sinking No. 18 shaft.1. AIR-LOCK AT No. 14 SHAFT.Some time ago it became desirable to raise and lower the McBride tunnel men to save them walking the inclined tunnel, about a mile in length, with a dip of nearly 600 ft., and a maximum gradient of 1 in 4. The main Upcast shaft, No. 14, was, therefore, equipped for winding the men. As this shaft was the main ventilating shaft for the McBride tunnel mine, it was necessary to take the greatest precautions against leakage of air. The writer therefore devised the concrete structure shown in Plate 1.The structure, as shown, surrounds the shaft inside the poppet legs. As the men are wound on double-decked cages (twelve men to each deck) provision is made at both top and bottom for the two decks to be loaded and emptied simultaneously. The doorsover the sky shaft, shown in the drawing, have been cut out and the sky shaft has been close-timbered with a double layer of T. and G. flooring boards, with building paper between, nearly up to the thimble frame, a small hole only being left for the winding rope topass through. The space between the ramps is glazed with plate glass to allow the winding-engine driver a good view of the pit top.The men are wound from two levels, 302 ft. and 611 ft.2. PIT-TOP GATES AT DUDLEY WINDING SHAFTTo minimise the shock to cage, couplings and rope when winding quickly, the writer devised the apparatus and arrangement shown in Plate n.

Jan 1, 1928

By K Haroon, J D. Speed, S P. Wood

Online analysis of continuous and batch processes has seen a dramatic increase in recent years, with examples ranging from petrochemicals to pharmaceuticals, to industrial biotechnology and food and drink. The particularly challenging environment of alumina processing has meant that instrumentation needs specific features and characteristics to be truly suitable, features such as: robustness, resistance to caustic conditions both in the analyte and the ambient environment, and reliability for long-term continuous use. Here we present the development of a novel FTIR spectrometer that achieves these requirements through the use of a static optics arrangement of mirrors, and stable diamond-tipped light-pipe probe. Firstly we give a very brief explanation of spectroscopic analysis, and the difference between FTIR and other infrared methodologies. Next we outline the novel arrangement of mirrors required to produce an interferogram without moving mirrors, and compare the benefits and drawbacks of this approach instead of conventional designs. We then share the results of laboratory analysis of synthetic Bayer liquors, with detection limits for aluminium hydroxide, sodium hydroxide, sodium carbonate and various sodium salts of organic acids. We then share the results of analysis on production samples, both in idealised laboratory conditions and then online in the process itself. Lastly we present work on in situ ultrasonic descaling solutions to avoid scale build-up and provide continuous cleaning of the probe – preventing the need for probe removal and manual cleaning.

Aug 24, 2022

By M Spagnolo, M Ashley, D, L Reemeyer

PasmincoÆs Century Concentrator in North West Queensland commenced operations in November 1999. The nameplate production capacity of 500 000 tpa of zinc metal production in concentrate was achieved in August 2002. Completion of the production ramp up was successful due to the culmination of a number of initiatives throughout 2001 and 2002. Mine to mill interaction to understand and eliminate head grade related bottlenecks affecting Concentrator production and reduce feed variation. Grinding circuit process development û operating and process control strategies to improve stability and reduce grind size to support zinc recovery. Pumping upgrades to control spillage in ultrafine zinc flotation Low density zinc flotation strategy û to improve silica-sphalerite separation to improve zinc recovery while maintaining acceptable silica in final concentrate. Flotation circuit process development û froth crowders, froth cameras and reagent control strategies to improve primary zinc flotation performance. Review and implementation of longer campaigns between planned shutdowns to improve availability. Team reorganisation û to improve setting and implementation of metallurgical strategies. This paper describes these initiatives and their contribution in achieving the production target. It also notes the ball mill motor failures that delayed the successful achievement of the ramp up, and CenturyÆs response to minimise the production impact. The paper also outlines the capital improvement program that was implemented to improve zinc recovery to design 82.5 per cent recovery once the production rate had been achieved.

Jan 1, 2003

By H Park, V Sahajwalla

"Due to the increasing amount of gangues in iron ores, a beneficiation process is required more as a preliminary step for ironmaking process. However, mechanical grinding and washing of iron ore needs tremendous effort that increases operating cost. Therefore, there is a necessity of a novel approach to ironmaking which can tolerate considerable amounts of silica or alumina. In the present study, a high alumina-carbon composite pellet was examined for an ironmaking process. The effect of compositional changes in the CaO-FexOy-Al2O3-SiO2 oxide system on the reduction of carbon composite pellets was investigated in a purpose built thermo-gravimetric analyser (TGA) at 1473K (1200¦C). As a result, alumina increased the reaction rate of carbon composite pellets by increasing surface area, while silica decreased the reaction rate by lowering surface area of samples. Infrared gas analysis assisted with the reaction kinetics of carbon composite pellets through measurement of CO and CO2 in off-gases. This study will assist with establishing the new pelletising method which differs from the conventional fluxed pellets.CITATION:Park, H and Sahajwalla, V, 2013. Effect of CaO-FexOy-Al2O3-SiO2 oxide system on the reduction of carbon composite pellets, in Proceedings Iron Ore 2013, pp 467-472 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

By R Lau

The fire safety design for road tunnels includes the following aspects: active systems, passive provisions and operational procedures. The active systems include the smoke control system, fire suppression system, detection system and fire fighter’s assistance systems. Passive provisions include escape passages, fire separation and fire resistance systems. The operational procedures refer to fire fighter access, reporting and alerts, evacuation processes and crowd control.Currently, these systems are typically designed by different designers or teams. These systems are intended to work together in a coordinated manner to provide the desired safety outcome. However, in practice, this is not always happening. The fire engineering process is supposed to bring together all these aspects and arrive at an integrated safety system. The fi re engineering process in practice is not integrating the design with the practice or reality and is thus arriving at less than desirably efficient safety systems.The example of design inputs shows how disconnected each system design basis is. The smoke control system design is based on the design fire size. The performance of the smoke control system is to achieve a smoke free environment for a defined space for a particular fire size – the design fire. The fire suppression system – most commonly sprinklers or deluge systems, is designed according to codes and to achieve a certain water discharge rate. The fire detection system is designed to detect temperature rise/rate of rise and perhaps density of smoke. Fire separation is determined to provide a certain period of service – mostly for structural elements. Escape route size and location is determined mostly by code compliance. Evacuation procedures are determined by Authority operational requirements rather than human behaviour.To arrive at an integrated fire safety system, the design basis and performances must be coordinated. An approach using fire scenarios would ensure all systems are designed to a common performance requirement. This paper will discuss how the current design approach outcomes compared with a fire scenario approach. More effective and efficient fire safety systems would require the stake holders to understand the implication of this approach and to embrace this through the fire engineering process.

Mar 8, 2011