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By R Sridhar, M Fe, W G. Bacon

The problems of magnetite build-up have plagued the non-ferrous pyrometallurgical industry for many years. To better understand these problems, a study was undertaken to determine the thermodynamic variables that affect the behaviour of magnetite under different smelting conditions. Equilibration studies were performed in the nickel smelting systems of matte-gas and matte-slag(silica saturation)-gas. The relationship of thermodynamic variables such as temperature, sulphur and oxygen partial pressure and matte grade on iron and magnetite activities were calculated and the significance on smelting parameters such as metal losses and partition coefficients were defined. The experimental data from this study were employed to develop practical methods which could be used to control the build up of magnetite, as well as to obtain additional metallurgical benefits. In general, a lower sulphur partial pressure and higher temperature operation was shown to enhance the metallurgical benefits of nickel smelting by decreasing the magnetite activity. Operating in this manner can also have added benefits such as higher metal recoveries, more efficient vessel utilisation and efficiency and lower smelter emissions at equivalent or higher primary furnace matte grades.

Jan 1, 2000

By J S. J van Deventer

Geopolymerisation is a new technology that processes and transforms aluminosilicate minerals into mechanically strong and chemically stable products. In this investigation, minerals such as fly ash and kaolinite were used as the solid raw materials for geopolymerisation. Inorganic salts were added to the geopolymeric pastes to simulate ionic contamination during processing for building and construction applications. The resultant products were examined and characterised physically. It was found that the early strength development of geopolymeric pastes could be changed according to the nature as well as the extent of the contamination. At a small dosage, the effect of the contamination on the early geopolymeric system depended heavily on the nature of the artificial surfaces that were created in the geopolymeric solution through the addition of the chemical additives. For example, the samples containing MgCl2 and Mg(NO3)2 had shown the same yield stress developments due to the similar surfaces that were formed. The cations of these salts were expected to hydrolyse and form magnesium hydroxide precipitates immediately after the addition to the early geopolymeric systems. The calcium cations of CaCl2 also precipitated upon addition, but the nature of the surfaces of these hydroxides was quite different to those of the magnesium hydroxides and gave rise to different yield stress development. The samples that contained the insoluble salts (in water) demonstrated different yield stress development when compared to each other because of the different nature of the additive surfaces that were exposed to the geopolymeric solution. These results suggested that heterogeneous nucleation could be responsible for the change of the rheological behaviour upon inorganic salt addition. When the extent of the ionic contamination was large, the anions released from the insoluble salts (in water) changed the nature as well as the concentration of the geopolymeric solution and the setting processes were retarded. Oxides, in general, behaved very differently from other salts, indicating the uniqueness of the oxygen anions in a system rich in hydroxyl and silicate anions. The inorganic salt contamination in geopolymers did not show any significant signs of structural change according to the XRD diffractograms collected. The seven-day compressive strength was not lowered by the inorganic salt contamination and it could sometimes be beneficial to the product performance, for example, an increase of 20 MPa was induced by the addition of calcium oxide. Inorganic salts as chemical additives have demonstrated the potential to modify setting times of geopolymers without sacrificing much of the productsÆ strength and integrity.

Jan 1, 2000

Recent legislation in the environmental field gives the mining industry an opportunity to take timely action to address its image. Shifting the focus away from mining (the activity) to minerals (the resource) will enable the mining industry to stand on equal footing with other industries and will help minimise the vulnerability to political and interest groupsÆ interference.

Jan 1, 1993

By J Zhou, D M. Hunter, S M. Iveson, K P. Galvin

The REFLUX Classifier is used to perform particle separations on the basis of density utilising a set of parallel inclined channels positioned above a vertical fluidised section. In continuous mode, feed enters part way up the vertical section, while fluidisation water is introduced from below. Lower density particles are conveyed upwards and collected in an overflow stream, while high density particles segregate onto the inclined surfaces, settle to the base of the system and empty via an underflow stream. Pressure transducers are used to measure the suspension density in the vertical section. This suspension density is maintained by a pneumatically controlled underflow valve to maintain a target suspension density or ‘set point’.Previously, Galvin et al (2010) demonstrated the significant improvement achieved via a new laminar-shear separation mechanism, achieved by utilising closely spaced inclined channels in the REFLUX Classifier. For the separation of low-density coal particles from mineral matter, a channel spacing of 6 mm proved effective; however, for the separation of gangue minerals from much higher density minerals such as iron ore, the shear-induced lift needs to be even higher. In this paper, we examine the influence of two different channel widths on the continuous processing of an industrial iron ore feed in the REFLUX Classifier. It was found that when moving from 6.0 mm to 3.0 mm channels, the ability of the system to reject coarser gangue material and retain finer high density material across a particle size range from 0.125 to 1.0 mm was increased, resulting in a higher grade product.CITATION:Hunter, D M, Zhou, J, Iveson, S M and Galvin, K P, 2017. Influence of shear rate on separation of iron ore fines using the REFLUXTM Classifier, in Proceedings Iron Ore 2017, pp 205–210 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By C M. Evans, D Thomas

Solid EnergyÆs Wangaloa open cast coal mine was operated between 1945 - 1989, and remained closed and disused until 2001 when SENZ initiated a mine rehabilitation programme. It is nearing the final stages of physical and environmental rehabilitation, aimed at creating an aesthetically pleasing and useful landscape. The final goals of these efforts are to produce an area, which has recreational and educational value. SENZÆs holistic approach to rehabilitation has been undertaken, treating the entire historical mine footprint instead of focusing only on those disturbed areas and the minimum range of issues just to meet with legal compliance. Rehabilitation at the site has included overburden modification with an emphasis on stability, removal and replacement of unhealthy and invasive plant species, and an AgLime amendment to alter soil pH conditions, which would support native plant species. To date, most ongoing activities relate to final planting and plant upkeep, and maintenance of the landform including ongoing erosion control, pest control, environmental monitoring, and research. Environmental quality concerns at the site may be treated by using a combination of methods, including regrading and capping of acid-generating pyrites, soil treatment with AgLime, and passive wetland treatment within existing water courses. Following major works, the mine site area may be opened to the public for recreational activities, interpretive displays on historical mining activities, and observation and appreciation for otherwise unseen geological features. SENZÆs holistic approach to reclamation, rather than treating minor issues, will result in the former mine site being transformed into an asset and the environmental and financial liability associated with the closed mine being discharged. Former mine sites can be turned from environmental liabilities with no recreational or public value (and potentially dangerous to life) into sites that can be safely used by the public for recreational and educational purposes.

Jan 1, 2006

By D H. Lee, J F, J H. Rubinstein

This paper examines the problem of optimising the life-of-mine costs of an underground mine, focussing particularly on the costs associated with the underground development needed to provide access to and haulage from the ore zones. This mine optimisation problem is modelled as a network and a solution technique is outlined. The effectiveness of this solution technique is then demonstrated by applying it to a prototype test example and some actual case studies. Finally, extensions of this technique to other underground mining problems are discussed.

Jan 1, 2000

By D Lalor, N Goodman

The increasing demand for batteries is resulting in the development of large-scale projects for the production of key battery metals such as nickel and vanadium. Several of these projects plan to extract the battery metals from the ore via chemical roasting, leaving large volumes of waste iron oxides after fuming and/or leaching of the battery metals. These iron oxide wastes can be smelted in a HIsmelt furnace using biochar as the reductant, to produce clean, green pig iron with net zero carbon emissions. This green pig iron can then be added to basic oxygen or electric arc steelmaking furnaces to produce green, net zero carbon, steel. This paper describes the flow sheets and the economics for potential projects producing green pig iron via HIsmelt using waste iron oxides from nickel and vanadium production plants.

Sep 18, 2023

Minerals Industry - 5 Year Outlook AusIMM sponsored project Positioning the Minerals industry for the 21st Century Does this seem right for New Zealand?  To ascertain the industry's perceptions of issues and capacity to address them: Industry context and issues Capabilities of professional staff Access to professional staff Balancing supply and demand Industry must do it. Cannot wait for others.   Some observations... Negative image - constrains capacity to influence community and government Major repositioning of professional staff competencies required Existing organisational arrangements and capabilities are under pressure to change Difficult to access professional staff of required capability Facing significant external challenges - with real concern about capacity to address them Prevailing culture not suited to needs of the future High level felt need for change The industry has a choiceà We can define where we want to be and act decisively Or We can respond to the future as it unfolds.

Jan 1, 2000

By D R. Carr

The installation of the Flotation Capacity Project flow sheet in the copper concentrator at Mount Isa Mines Limited has recently been completed. The project involved increasing the flotation capacity with Wemco tank cells and Jameson cells as well as changing the copper cleaner circuit layout. The engineering design and construction for the brownfield expansion had significant involvement from operational, maintenance and technical personnel adopting the same approach as the highly successful George Fisher project in the Lead/Zinc Concentrator at MIM. The involvement of people familiar with the concentrator allowed for smooth integration of the changes into an operating concentrator with minimal downtime. Detailed circuit analysis over many years identified opportunities for improvements in the flotation circuit for both grade and recovery. This paper describes the program of work that led to the Copper Concentrator Flotation Capacity Project, and the implementation of the circuit expansion and flow sheet changes that resulted in an overall improvement in the circuit recovery.

Jan 1, 2003

This paper discusses the application of a computerised model based on genetic algorithms (GAs), called GenRel, for reliability assessment of underground mine hoisting systems. The purpose of this paper is to investigate whether GenRel can be applied to predict future failure data of a mine hoisting system based on historical records of failures. The incentive of selecting the GAs for prediction of failures is that GAs are a class of evolutionary algorithms which imitate the biological evolution procedures such as reproduction, selection, crossover and mutation. The reliability of mining equipment changes over time due to an array of factors (eg equipment age, the operating environment, number and quality of repair). These factors affect the equipment's failure patterns and have complex impacts on the equipment's reliability characteristics. The failure patterns are assumed to follow a biological evolution process, and thus GAs can be considered applicable in the modelling process.To conduct the reliability assessment, a study was carried out with historical failure data of hoists in the time period from January to December 2007. Two failure data sets of two mine hoisting systems were collected from two typical underground mines in Ontario, Canada, which are denoted as the NA mine and the SB mine. The failure data sets were prepared in the format of time between failures (TBF). Then, these data sets were entered in GenRel to generate predicted failure data sets for the period of January to March 2008. The paper discusses the statistical similarity of the actual failure data sets for the period of January to March 2008 with the predicted failure data set generated by GenRel in the same time period.

Dec 6, 2010

This is what I term ... the graveyard end of any Conference. It's almost over. Those of you remaining are either all talked out or past the information overload stage. And some of the sensible? ones have left for more exciting field trips, or gone back to their work-site where they earn their daily crust, or headed off South to another Conference of interest to the Energy sector that is being held currently in Christchurch. But that's OK. I have a thick skin! And neither am I particularly Politically Correct! I am not a miner: I am not involved in the mining industry in a hands on way at all. I am not even an academic. I am not even too sure why I am here ... apart from the fact that I agreed to come! At various times in my life I have been a D istrict Councillor, Chairman of a Regional Council and even an MP. I am a supporter of responsible mining.  All of what I have to say is my own point of view rather than that of either the Coal Producers' Federation or the mining industry. That is not to say that we are often in agreement, but I thought I would clear that point right at the outset. And some of what I will talk about will not strictly be to the topic - it's hardly mind-bending riveting stuff. Well, is it? But obviously because you are still here you have some interest in the topic.

Jan 1, 1997

Phosphorus Phase Analysis of Medium-Low-Grade Rare-Earths-Bearing Phosphate Ores

Sep 13, 2010

By S Jahanshahi, D R. Swinbourne

The classical metal-slag-gas equilibrium technique was used to study the thermodynamic activity of cobalt, iron and their oxides in iron silicate based slags containing under controlled oxygen potential (3.70 x 10-8 to 2.95 x 10-7 atm) at 1573 K. The measured activity of cobalt oxide in FeOx-25 wt per cent SiO2 slags showed positive deviation from ideal behaviour for melts with up to ten wt per cent CoO. At higher silica contents, the behaviour became closer to ideal and in accord with previous studies on silica saturated slags. The activity coefficient of FeO in these slags had virtually no dependence on the CoO content. Partial substitution of silica by lime resulted in an increase of the activities and activity coefficients of CoO, FeO, Fe2O3 and Fe3O4. The results indicate that saturation of the slag with a magnetite phase occurs at CaO contents of five wt per cent and higher. Phase equilibria studies SiO2-FeO-Fe2O3-CaO slags containing cobalt were also carried out using the drop-quench technique. Results from these experiments confirmed the formation of a magnetite solid solution containing about three wt per cent CoO at lime contents of five wt per cent and higher at 1573 K and 2.9 x 10-7 atm of oxygen.

Jan 1, 2000

Alluvial gold was found in the Terawhiti area, West of Wellington, in the 1850s. This led to the discovery of reef gold. Periods of minor 'gold fever', company flotations, and mining activity occured between 1869 - 1973, 1881 - 1986, and in the late 1880s, with one final company active in 1911 - 1914. 1n the early 1980s, further field work was carried out. No viable mining operations resulted from any of this activity.

Jan 1, 1993

By G Wyartt

Systems such as Davey Bickford’s Daveytronic® SP blast initiation system and electronic detonators have been an integral part of drill and blast activities in Australia for over a decade, with the significant benefits of electronic blasting well documented. Since 2010 the Multiblast feature has been commercially available, which enables eight individual blast patterns (up to 1500 detonators each) to be blasted in the same firing window. Synchroblast has been in active operation since 2012, which allows a blast of up to 4500 detonators – either as a single blast pattern, or several smaller adjacent blast patterns – to be reliably initiated.Multiblast manages blasts separately but concurrently, allowing all blasts to conduct prefiring checks simultaneously from the firing point utilising only one remote blasting unit. Each blast can be selected and fired individually, in a sequence determined by the operator by scrolling through the colour display. Synchroblast automatically detects the blasting configuration, and manages all detonators as a single blast pattern. This simplifies the design and blasting processes for the mining operation.Multiblast and Synchroblast are routinely employed throughout Australia and globally in both open cut and underground operations, enabling optimal productivity due to increased blast volume and reduced operational downtime associated with blasting events.A number of case studies will be presented in this paper, detailing various mining operations that are consistently blasting in excess of 2500 detonators per blasting event as a part of standard drill and blast operations. Blasts over 3000 detonators are becoming more frequent as mine planning departments adapt to this operational capability and flexibility.CITATION:Wyartt, G, 2017. Multi and Synchroblasting – maximising operational productivity, in Proceedings Iron Ore 2017, pp 631–634 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By C Ferron, R Massimi

There is approximately 240 000 tonnes of arsenic trioxide dust stored in underground chambers at the Giant Mine in Yellowknife, Northwest Territories, Canada. To minimise the amount of arsenic released to the environment, a number of closure alternatives are being considered. One alternative is to mine the dust, encapsulate it and dispose the mixture into a secured landfill. The potential leaching behaviour of the encapsulated dust was examined in a laboratory programme. Cylinders of arsenic trioxide dust mixed with cement/aggregate and bitumen were prepared. The dust content varied between zero per cent and 60 per cent of dry weight charge. The cement cylinders were tested for strength, leaching and freeze/thaw durability. The bitumen cylinders were tested for leaching only. The results show that increasing dust content in the cement cylinders negatively impacts the strength and the freeze/thaw durability of the samples. A contributing factor is likely the high water to cement ratio in the samples. Leaching tests show that arsenic release from cement cylinders increase with increasing dust content. Arsenic concentrations in leachates do reach a plateau at a certain point in time. Arsenic release from bitumen cylinders was significantly lower compared to cement cylinders. Arsenic concentrations eventually were less than 0.05 mg/L in samples containing up to 25 per cent arsenic trioxide dust. Arsenic leaching rates were found to decrease by an order of magnitude over the course of three months.

Jan 1, 2003

Grinding and Beneficiation Characteristics of a Low-Grade Haematite Ore

Sep 13, 2010

Newmont Waihi Operations is participating in the initiation of a community liaison forum in association with the local district council. The objective is to provide a forum for the free and regular exchange of ideas, concerns and information, and through improved communication seek to achieve a more comprehensive set of solutions to community, operating and closure issues associated with Martha Mine. A similar liaison forum has been operated on two previous occasions during earlier phases of the present mine's operation. This paper deals with the practical aspects of setting up a liaison forum to act as an effective conduit between regulators, mine operators, local businesses and the community. The mechanisms and procedures for identifying community issues and concerns are dealt with. The actions and structures required to ensure effective ongoing community 'buy in' at all levels are discussed. Corporate philosophies are addressed. Specific examples from Martha Mine, Waihi New Zealand will be used to illustrate the paper. This will include a brief explanation of previous and current community issues, Newmont Waihi's operations both at Martha Mine and the proposed Favona underground mine, and the practical issues involved in setting up a liaison forum.

Jan 1, 2003

The Department of Mineral Resources is the lead agency in mine site environment management and control inNew South Wales. The Department introduced a Mining, Rehabilitation and Environmental Management Plan (MREMP) process several years ago in order to integrate the activities of other government agencies who may have a material interest at the mine site. The MREMP process has resulted in a spirit of trust and co-operation between agencies and between agencies and mining companies. The spirit of co-operation has been reflected in greater public confidence that mining is environmentally responsible.  

Jan 1, 1995

By P G. Hicks

The influence of feed size and pulp density on the specific rate ofbreakage of quartz was investigated. Plots of log fraction of feedremaining within the feed size interval against grinding time allowed the application of the first order grinding model to be examined. Substantial non-linearities were observed for all feed sizes due to environmental and material factors. For feed sizes above 1.3 mm, the specific rate of quartz breakage was higher with rod milling than ball milling, but below this size the reverse was true. Material that remained in the feed size interval after the initial grinding broke more slowly in subsequent grinding than the original feed material. Grinding media and time as well as feed size influenced the effects of pulp density on grinding. More dilute pulps (eg 50 per cent solids density by weight) were favoured for higher rates of breakage in rod milling but for ball milling, the optimum pulp density appeared to be 60 to 70 per cent solids by weight.

Jan 1, 1998