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By G L. Simmons, K M. LeVier, R Kappes

The low potential hydrophobic state of pyrite in amyl xanthate (PAX) flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at NewmontÆs Lone Tree Plant in Nevada. Initially, the N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments, and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Experimental results show the importance of the pyrite surface state and the rather interesting features of the activation process.

Jan 1, 2005

By Nag D. K

The Dolphin Scheelite orebody is located near the old mining town of Grassy on the south-east comer of King Island in Tasmania. Surface open cut mining of the Dolphin deposit was conducted for a number of years, then the proximity of the sea and adverse stipping ratio led to underground mining. As a result of the variable orientation and dimensions of parts of the orebody a number of mining methods were practiced at the Dolphin mine until 1990 when a combination of high processing and surface site costs coupled with low tungsten prices led to the cessation of operations. In this paper the different mining methods practised are examined and critically reviewed. The more successful mining methods were developed with experience and improving equipment technology to the extent that the underground operation produced ore at the lowest unit cost during the final years of operation.

Jan 1, 1995

The purpose of this study was to investigate the effectiveness of froth fl otation for the recovery of gold from the gravity tailing stream of the former Lihir Gold Limited (LGL) operation in Ballarat. The P80 of the tailings was determined by screen analysis as 1 mm, with test work conducted on as received material along with samples ground to P80 sizes of 47, 78 and 134 microns. Laboratory scale batch flotation tests were conducted at both natural and elevated pH to investigate the impact of pyrite depression on gold recovery. Results indicated that although an increase in grade from approximately 0.7 g/t to 3 g/t was achievable at a natural pH and a P80 of 134 micron, gold recovery was low at just 35 per cent. Finer grind sizes were found to have an adverse effect on both grade and recovery. Future efforts will be focused on the sub 310 micron size fraction of the tailings, which was revealed to contain approximately 85 per cent of the available gold and may be amenable to cyanidation or ultra-fine gravity treatment.

Aug 1, 2010

Detailed underground mine design and optimisation studies undertaken by the author over the past few years have clearly demonstrated that additional value can be created by varying the cut-off grade (COG) spatially throughout a deposit as well as over time. This additional value can be particularly significant for marginal operations. This paper, by way of worked examples, illustrates the conceptual and practical considerations of applying a differential cut-off policy for an underground mine to both maximise value and manage risks associated with production and metal price volatility. Consideration is given to both the design stage of a new mine and to the strategic and practical application of a differential cut-off policy in an operating mine.

Jan 1, 2005

By Forssberg E

This paper presents the experimental results on the effects of slurry Theology on ultra-fine grinding by a stirred ball mill. The amount of dispersant, slurry density and the particle size were selected as the parameters. The viscosity of dolomite-water slurry was measured by rotational viscometers. It was found that by adding enough dispersant, the effect of particle size from 1 to 10 pm on the slurry theology could be eliminated, but a strong effect of slurry density (tested for a range of 65 to 75 wt per cent) remained. The use of dispersant transformed the slurry from Bingham plastic flow to dilatant flow, which reduced the yield stress to zero, but increased the viscosity at higher shear rates. During the milling process, the viscosity was stable. The yield stress, however, increased suddenly from zero after a certain milling time. The mill operation stopped at the point where the yield stress increased due to poor slurry fluidity. The milling efficiency was found to be higher at a lower amount of dispersant addition or a lower slurry density within the experimental limits.

Jan 1, 1993

By P Thompson, D Rose, S Yu, W Baum, R Zahn, D Meadows, G Hall

Opportunities to improve mill operations are often cited by mining companies and recognised in many concentrators spread throughout the world but are not always followed through. Copper-molybdenum concentrator operations are challenged by a continuously increasing list of detrimental factors. They include deteriorating ore characteristics and poor mineralogical information on deeper ores, water quality and availability, steel wear and increasing power costs. Rapidly declining productivity, sustainability and environmental factors, new taxes, mining industry global skill set shortages, to name but a few, must also be considered. The days of maximising value by just increasing production or simple cost cutting are fading and will not be sufficient for the future of more complex mineral processing operations and larger plants. As a result, FLSmidth’s Global Process Technology Group has launched a plant and process optimisation program based on mineralogical and metallurgical surveys.Copper-molybdenum concentrators of the future need a paradigm shift. Modelling and simulation tools alone are not the answer to complex mineralogical associations and larger scale equipment and operations. Detailed area by area review aimed at identifying process constraints in terms of equipment and operating practice in conjunction with robust diagnostic work, ie mineralogical and metallurgical characterisation, are mandatory for process optimisation. The navigational beacon, for all operations who want to remain competitive, will be ‘process efficiency’. Since the use of automated mineral analysers has become more readily available and reliable, mineralogical-metallurgical plant surveys have proven themselves as the most efficient tool for optimising plant performance.The following paper will illustrate how operations can move toward eliminating under-performing flow sheets, fixing run-away flotation conditions, maximising individual process equipment performance, preventing shortcuts in Bond work index testing which may cause the failure of comminution models and minimising costly and time-consuming ‘debottlenecking’. As previous plant surveys have shown, the net project cash flow can be increased by 50 to 200 per cent if a combination of robust ore characterisation and plant process mineralogy is performed. The combined plant survey approach has been demonstrated successfully in a multitude of operations. This includes the use of key ore types in concert with statistically sampled process streams, bench-scale metallurgical tests and automated mineral analysis on a size-by-size basis.CITATION:Meadows, D, Hall, G, Rose, D, Thompson, P, Baum, W, Zahn, R and Yu, S, 2014. Copper-molybdenum concentrator surveys using mineralogy and process benchmarking tools to improve overall plant performance, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By D Hatton, S Wilson, F Orrante, M Taghimohammadi, F van der Walt, N Arslan, M Westcott

"Cayeli Bakir Isletmeleri is an underground copper-zinc mine in turkey. The ore is highly variable with feed grades ranging from 1–4 per cent copper and 1–10 per cent zinc. Due to this variability, ore characterisation and blending strategies are crucial for performance optimisation.This paper presents a case study for a multidisciplinary approach to process optimisation, integrating Geometallurgical and advanced control methods to achieve optimised plant performance. The results from comprehensive metallurgical tests and surveys were used to develop a mathematical model utilising SGS’s Integrated Geometallurgical Simulator® (version number 2.5.24.0). The model was employed to determine the most appropriate operational settings required to ensure that optimised grades and recoveries are achieved for each ore type.SGS’s Modular Expert Technology (MET) expert system was then implemented to target these optimum operational ranges utilising online grade and froth velocity measurements. The successful conversion and deployment of the modelled process parameters into an expert system has resulted in significant improvements in overall recovery and circuit stability.Citation:Arslan, N, Westcott, M, van der Walt, F, Hatton, D, Taghimohammadi, M, Orrante, F and Wilson, S, 2016. A Multidisciplinary Approach to the Optimisation and Control of a Copper-zinc Grinding and Flotation Circuit, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 115–122 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By L Lorenzen, H Muller

"Every year a large number of projects are evaluated by small listed and unlisted mining companies that are hoping to find the ideal project, which will catapult them from a mining junior status to that of a mid-tier mining company. Usually this includes finding the æidealÆ or ærightÆ orebody and then developing a process which will allow cost-effective recovery of the valuable metals and the production of a saleable product. These dreams are seldom realised and there are a number of good and obvious reasons for this. Issues that are generally high up on the agenda for the smaller companies are: cost of developing a project before the feasibility study stage finding a suitable, or optimum processing technology financing of the project dealing with risk.The most expensive part of the development process for the small miner is often the exploration side of the business and finding the æidealÆ orebody. However, finding the right orebody will not be discussed in this paper. The æidealÆ orebody does not necessarily solve the problems of the mining junior, as much of the uncertainty lies in the process required to recover and produce the final metal product. Once a mineralised deposit has been identified and the grade at least reasonably qualified, the development of a suitable process becomes the driver to convert the deposit into an orebody. This paper proposes that a small exploration company has a very limited opportunity to succeed if it does not do sufficient homework before it identifies the æidealÆ orebody. The risk profile for the small mining company, by its very nature, has to be different to that of a major company and as a result the opportunities often lie in managing different and often new process options, which may be the key to bring such projects on line successfully.CITATION:Muller, H and Lorenzen, L, 2012. Project selection and process development for mining juniors, in Proceedings Project Evaluation 2012, pp 149-158 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 24, 2012

By Ulvelin K, Antila K

Large scale cut and fill mining in narrow silver-lead-zinc orebodies began at Mount Isa in 1964. Initially each orebody was one stope and access was via raises from the level above. Upholing was the principal mining method, although flatbacking was employed where ground conditions were more difficult. Developments since have included access via footwall inclines and connection of all stopes with major crosscuts. Flatbacking is the principal method. The most recent cut and fill operation is now fully mechanised using drilling jumbos, rockbolting jumbos and load-haul-dump units. Improved ground support and drilling and blasting practices have enhanced safety, recovery and productivity in all cut and fill operations.

Jan 1, 1988

The New Guinea Mobile Belt is the northern zone of the Melanesian Orogeny (Dow and Sukamto, 1984), which consists of a complex zone ofupthrusted and accreted, regionally metamorphosed geosynclinal sediments and volcanics of Mesozoic to Eocene age and the overlying sediments. On the northern margin of this accreted terrane, formed an Eocene to Middle Miocene island arc. The North New Guinea Basin formed during the Upper Oligocene on the accreted margin. The depositional history of this basin is complicated by major crustal movements during the Upper Miocene to Holocene. During the Middle to Upper Miocene two magmatic arcs were emplaced. The northern magmatic arc is in part, spatically and genetically related to the Eocene to Middle Miocene island arc. The Maramuni-Utawa Magmatic Arc (southern) is a result of the Oligocene accretion and regional metamorphism. Coincident witt these magmatic arcs are belts of mineralization containing porphyry Cu-Au, epithermal/hydrothermal Au, Ag + Cu-Pb-Zn, exhalative Cu-Pb-Zn + Ag-Au, lateritic Ni-Cr-Co + PGE and alluvial Au, PGE, Cr occurrences and deposits. An intergrated tectonic model is presented for these and other data for the northern zone of the Melanesian Orogeny.

Jan 1, 1990

Changes in prices and costs change the mineable grade and the profitabil- ity of an ore reserve. In a static world the grade required for an ore reserve is measured by the ratio: Cost/tonne of ore x 100 Price received/tonne of product and profitability by the ratio:- Price received/tonne of product Cost/tonne of product If the words cost and price refer to average cost and average price over some suitable period, say 3 to 5 years, the above ratios express the convent- ional wisdom of the mining engineer, and assume there will be no change in technology or politics.

Jan 1, 1979

By J Zhou, X Bi, Y Yan, W Peng, H Yang, D Weng, P Li

Fortescue Metals Group (FMG) fines from Western Australia is a hematite and limonite mix characterised by high crystal water content. Due to its higher supply capacity and lower prices, the Wuhan Iron and Steel Corporation (Group) intended to use more FMG fines in the sinter mix. It is understood that sinter quality is closely related to its microstructure featured by the hardness and brittleness of different mineral phases, the content of micro pores, and trans-cracks. In order to maintain sinter qualities such as tumble index, reducibility and so on at higher FMG fines blend ratios, a research project was initiated to study the effects of the FMG fines blending ratio on sinter microstructure. Research results showed that at higher FMG fines ratios, the hardness of hematite and magnetite were both decreased while the hardness of calcium ferrite showed a tendency to decrease. The number of cracks that were generated during Vickers hardness measurement in various mineral phases decreased, but their length was shortened, and the variation of crack lengths increased. The contents of hematite and magnetite were also reduced and the reduction of magnetite was clearer. Also the content of calcium ferrite and pores rose and the magnitude of the increase of pores was greater. Among all the mineral phases in sinter cakes, the Vickers hardness of hematite was highest within the range of 879 N/mm2 ~ 942 N/mm2, and therefore the decrease of its content in sinter and the enhancement of its brittleness, ie the number of cracks increased, were harmful to sinter strength. In addition, the excessive increase in pores content is also not favourable to sinter strength.CITATION:Bi, X, Yan, Y, Zhou, J, Peng, W, Li, P, Yang, H and Weng, D, 2013. Study of sinter microstructure with various blend ratios of Fortescue Metals Group fines, in Proceedings Iron Ore 2013 , pp 331-336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Matsuo T, Uga Y

The tunnelling work to construct a sewage trunk line designed by the Sewage Bureau of Kobe City along north side slope of Rokko mountain range incorporated an all ground condition type (broad spectrum) TBM with slurry transport system with jet pump manufactured by Kawasaki Heavy Industries, Ltd. Boring dia. of the tunnel measured to 2.0 m. The construction planning and implemen- tation were done by Ohbayashi Corporation, the general contractor. The heading way was 3342.4 m in overall length.; construction work ran from April '84 to June '85. The max. daily progress marked 31.9 m and the max. monthly progress 493.1 m according to the relevant record. The machine proceeded with the work under geological conditions featured with conglomerate, rhyolite, tuff breccia and slate, whereby soft soil zone mostly of clay was encountered in a limited area. In the latter case, however, steel segments were substituted for supporting steel ribs. The tunnel was routed beneath a meandering road with the result that more than 40% of overall length show a curvature of 50 to 200 m radius.

Jan 1, 1987

By S DeKruijff

The Mount Isa Mines Copper Mine in Mount Isa started producing copper in 1966. The Copper Mine gradually increased production rates to nearly six million tonnes per year. Over the last three years the mine has been in a gradual ramp down due to the reduction of primary ore sources and head grade. The majority of ore sources are predominantly in pillar retreat sequences bounded by multiple fill masses. There also a substantial lower grade resource delineated to the south of the main orebody. These remaining ore sources present significant engineering challenges to obtain a safe and cost-effective extraction. Stope designs have become increasingly complex and require additional engineering and operations input and analysis. This paper describes the major planning and operational challenges and issues associated with the stope design and extraction of an orebody in the later stages of mine life.

Jan 1, 2000

By Lo YC, Pate WT

In recent years there has been a great deal of interest in ways to optimise the performance of mineral processing plants. This paper describes a methodology developed for optimisation of autogenous and semiautogenous mills. The methodology involves plant sampling, batch testing, modelling, computer simulation, control strategy evaluation and implementation. The models have been tested in plant operations to verify the research findings and predictions. Two example applications of this approach to plant optimisation are presented. Benefits reported in these two examples are in the range of four - eight per cent increase in size reduction efficiency.

Jan 1, 1993

The law including legislation such as the Occupational Health & Safety Act 1983 imposes stringent obligations on employers to ensure the health and safety of their employees. The use of pre-employment medical examinations is one tool that employers can use to assess the suitability of a job applicant for a particular position and protect themselves from prosecution or claims for compensation or damages.At the same time, however, legislation such as The Disability Discrimination Act 1992 (Commonwealth) ("DDA") and The Anti-Discrimination Act 1977 (New South Wales) ("ADA") affords protection to individuals against discrimination.

Jan 1, 1998

By P Joyce, A S. Ray, P S. Thomas, J Haggman

Climate change and global warming present a significant challenge as unsustainable levels of greenhouse gas emissions arising from human activities continue to be emitted. The cement industry is responsible for between five and ten per cent of annual world carbon dioxide emissions; most arising from the manufacture of Portland cement (PC). An effective way of reducing emissions is by incorporating supplementary cementitious materials (SCMs) as partial PC replacements. SCMs are silicate or aluminosilicate based pozzolanic materials which, in finely divided form, combine with water and calcium hydroxide (lime), liberated by cement hydration, to form compounds exhibiting cementitious properties. Pitchstone is such an aluminosilicate and has the potential to act as an effective pozzolan for partial replacement of PC. In North Queensland, Australia, a vast deposit of pitchstone is mined and processed for expandable perlite aggregate. During the classification stage of the excavated natural material, waste pitchstone fines (PF) less than 0.5 mm in size are generated. This study evaluates the waste PF as a viable, eco-friendly pozzolan for the partial replacement of PC. The reactivity of the PF is compared to fly ash (FA), using the pozzolanic compressive strength activity index (SAI) after seven, 28, and 91 days ageing at 20 per cent and 40 per cent PC substitutions. PF was found to be comparable to FA as a pozzolan at 20 per cent PC substitution at all ages tested. However, for the 40 per cent substitution blends significant strength was only achieved at 91 days ageing for the FA blend. The pozzolanic reactivity was also investigated using thermogravimetric analysis to determine the degree of free lime present after 91 days. In all cases where an SCM was added, the free lime was observed to be consumed with increasing age.

Jan 1, 2008

By A Fern, A Hawkes, o, W Smith, K Mee

Serious Injury and Fatality (SIF) prevention remains a priority focus within high-risk industries sector. A major mining operation sought to strengthen their approach to the management of high-risk activities through an in-depth review of all historical incidents that had serious injury or fatality potential (SIFp) events (sometimes known as hi-potential events). The analysis found that the organisation invested a disproportionate level of resources, time and effort on low consequence incidents with a high proportion of SIFp incidents going under the radar. It was found that 76 per cent of SIFp incidents were rated in moderate or lower risk categories and conversely, almost half of those incidents with a ‘serious risk’ rating had little or no potential for a serious outcome. As a result of this project, the operation engaged in a renewed focus on critical risk management and enhanced its operating cadence in critical risk for the workforce. This included bow tie analysis, an update to critical risk standards and increased workforce engagement in the use of critical control verifications in the field. Data analytics with lead and lag indicators continue to provide senior leadership team and risk owners with an understanding of exposure for SIFp and control effectiveness. The audience will take away learnings from a real-world case study that provides data-driven insights of the human, local and organisational factors contributing to incidents with SIF potential. In addition, participants will understand the steps taken to categorise and analyse this incident data and the initiatives currently being implemented by the organisation as a result.

Apr 16, 2024

By Kapoor M. L

Emf measurements on SE galvanic cell: SS; Ni-NiO I solid electrolyte/ZrO2 + CaO I [Pb + Bi]liq alloy; (PbO); SS were made in the temperature range 913-1034 K to determine the thermodynamic properties of oxygen dissolution in liquid lead. Bismuth alloys with bismuth in the dilute concentration range of 0 to 3.08 mass per cent and oxygen in the alloy varied by equilibrating the metallic system with a suitable (PbO) slag. Wagner's interaction parameter approach was used to calculate the ternary interaction parameter, eBiO at temperatures of 913, 953 and 993 and 1034 K and to observe the temperature dependence eBiO = 19 200/T - 17.454. Quasichemical fonnulation was employed to yield lnf BiO and reveal the effect of bismuth on oxygen in lead. The results obtained are discussed on the basis of theoretical models and the value of Wagner's energy parameter 'h' estimated to predict the results in a Pb-Bi-O system.

Jan 1, 1995

Just as Australia is part of the Pacific Rim, so the Pacific Rim should be viewed as part of the whole world. That applies in particular to that scarce commodity û money. There are five main factors of production in any mining development û mineralisation, materials, manpower, management and money. LetÆs focus on the upstream input û mineralisation, and the downstream input û money, especially in the area of communications. Unknown to many, the Competent Person reporting on Mineral Resources and Mineral Reserves has a direct and unavoidable impact on the companyÆs financial statements û the profit and loss account and balance sheet. With respect to reporting of the major asset of most mining companies û the resources/reserves û investors are getting a better deal now than at any time in memory as regards flow and adequacy of information. Australia has been a world leader in this regard. The outlook is for even more informative and useful reporting. The more rigorous reporting requirements for Exploration Results and Mineral Resources/Reserves, which have become a worldwide phenomenon over the last five years, will continue. This will be positive for the mining industry as a whole and for Australia in particular. However competition for the scarce investment dollar will also increase. Put simply, mining has many competitors, unconnected with mining, for the capture of the investment dollar. It behoves all participants to recognise that there are three investment factors which influence strongly the willingness of investors to put money into mining. These are Confidence, Credibility and Consistency. AustraliaÆs investment image stands high in these three respects, but the competition will continue to grow. AustraliaÆs lead must be maintained. However, some investment decisions should not necessarily be based on fundamental, quantifiable facors. Some of these are outlined.

Jan 1, 2004