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By R Wynn, T J. Akroyd, C Costa

In an environment of lower zinc prices, falling revenues and reducing zinc feed grades, Century mine implemented a fast-tracked capital upgrade program in less than 15 months. The program was designed to increase ore milling throughput capacity by 20 per cent and optimise the capacity of the flotation plant to increase zinc recovery by approximately 2.5 per cent whilst maintaining final zinc concentrate grade.A key aspect of this program was minimising capital expenditure by better utilising existing capacity and only adding capacity where absolutely required to address critical processing bottlenecks. By gaining an understanding of plant process bottlenecks and future ore blends, and by carefully selecting appropriate technologies for particular specific flotation applications, maximum return on minimal capital investment was achieved.The close collaborative work achieved between the metallurgy processing department and other operational departments on-site was also critical to the success of this project. This work increased the mining and processing capacity of the mine and port site respectively, such that the full value of the process plant modification could be achieved.Capital payback on this investment was achieved in approximately three and a half months.This case study demonstrates the extra value to a mining business that can be achieved through fully understanding the mining/processing value chain and by careful targeted action to address critical bottlenecks in the processing chain from the mine through to the port site.CITATION:Akroyd, T J, Wynn, R and Costa, C, 2014. MMG Century Mine, a case study – maximising project net present value through targeted capital expenditure and process optimisation against a backdrop of falling metal prices and feed grades, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 417–426 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

Efficient project planning during the detailed feasibility to final engineering stages of a project requires not only the accurate prediction of the grade, tonnes and recovery, but their degree of variability as well. An understanding of the major parameters involved in the grade and tonnage estimates is essential, and the communication to those receiving the results is most important. The personnel involved in the project require more than just a global reserves classification. Quality parameters other than grade should be evaluated as carefully as the estimate itself. This paper does not present any novel ideas to overcome or enhance any of this. Rather, it takes a step back and tries to look at the global picture of requirements for proper project planning.

Jan 1, 1987

By H Law, M Muller

Mount Isa Mines (MIM) Copper Concentrator currently utilises Agitair 120 banks for its roughing flotation circuit. Apart from a rotor change, the only other significant work completed to the Agitair banks since their installation and commissioning over 40 years ago has been a like for like refurbishment in 2016. The Agitair banks at the MIM Copper Concentrator currently utilise the Pipsa rotor design which progressively replaced the original Chile X rotor design in the 1980’s and 90’s in the copper concentrator. Since the development of the Pipsa rotors, modern rotors such as the Dorr-Oliver (DO) high shear rotors have been released to the market with proven recovery and concentrate grade improvements over previous rotor designs. This paper aims to detail the installation, testing and comparison of Pipsa versus Dorr-Oliver rotors in two different flotation sections of the MIM Copper Concentrator.CITATION:Muller, M and Law, H, 2018. High shear rotor trials in the Mount Isa Mines Copper Concentrator, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 393–402 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By L Gobbo

X-ray diffraction (XRD) provides useful information about the composition of an ore sample in terms of quantification of crystalline phases and amorphous content. The use of new, fast detection systems implemented in CubiX FAST industrial diffractometers creates the opportunity to use this technique in exploration and modern process control. Besides the chemical composition of iron ores, their phase composition is also an important factor for exploration, quality control and processing. In the analysis of iron ore, XRD can identify the phases containing iron, such as haematite Fe2O3, magnetite Fe3O4, and goethite FeO(OH), and any other mineral phases present, especially silicas. Quantitative analysis is possible by various classical methods such as straight line or polynomial calibration with standards, but modern quantification analysis techniques such as Rietveld analysis or full pattern autoscale analysis are attractive alternatives, as they do not require any standards. These methods offer impressive accuracy and speed of analysis. Another analysis technique offering great benefit to ore exploration and process control is cluster analysis. This technique greatly simplifies the analysis of a large amount of data, eg from drill core samplings, and automatically sorts closely related scans of an experiment into separate clusters and marks the most representative scan of each cluster as well as outlying patterns. This can facilitate multi-dimensional compositional mapping of ore deposits, identifying regions of favourable mineral composition and allows fast and reliable tracking of the process. It is the most economic procedure to have automatic data evaluation without involving any dedicated personnel in the process. Details of the techniques used, sample optimisation methodologies, results, data precision and limitations will be discussed. The approaches have enormous potential as an inexpensive, reliable tool, useful in the characterisation of iron ore materials in an industrial environment.

Jan 1, 2009

Tourmaline-bearing rocks are a rare rock type of Suites 3, 4 and 5 at Broken Hill. Minor laminated plagioclase-quartz-tourmaline rocks occur in association with the quartz- magnetite rocks of Suite 3 with the greatest abundance of tourmaline-bearing rocks present in Suite 4 intimately associated with lode horizon, scheelite mineralisation and zinc mineralistion - all approximate strike equivalents of the Broken Hill Pb-Zn-Ag deposit. Bedded quartz-tourmaline rocks, tourmalinites, tourmaline-rich pelite and tourmaline-bearing lode horizon have been recorded from suite 4. The bedded tourmaline rocks rarely display cross bedding, graded bedding, slump structures and small scale intraformational breccias. Minor tourmaline-gahnite-bearing pelites are present in Suite 5. The sedimentary structures, metamorphic textures, the stratigraphic position of the tourmaline-rocks and the presence of quartz-tourmaline-gahnite-spessartine (-fluorapatite) lode rocks indicates that the mineralisation at Broken Hill and the tourmaline-rich rocks are all products of submarine exhalative hot spring systems which were most active during deposition of Suite 4 rocks. Tourmaline is chemically different from that associated with granitic activity and from other submarine exhalative tourmaline-rich rocks because the premetamorphic alteration at Broken Hill involved addition of Fe, Ti and F and subtraction of Mg - a feature reflected in the chemistry of tourmaline from Broken Hill.

Jan 1, 1983

By W Newns

This paper describes laboratory and in situ tests and determines a set of parameters for stiffness and strength properties for a weak sedimentary rock mass, the East Coast Bays Formation of Auckland. The parameters derived are discussed in relation to peak strength and in respect of deformation limits associated with sequential excavate and support (SEM) or conventional tunnelling.

Mar 8, 2011

By Sans H

The geostatistical Discrete Gaussian (DG) model is demonstrated to be capable of providing an effective means of implementing change of support for Enterprise-style mineralisation and thus providing reliable global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively skewed, therefore significant deskewing of the histogram and reduction of variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced short range structures are observed in variograms. The experimental test was run for a change of support for which the variance reduction was. approximately 60 per cent. This reduction is similar to that predicted by Krige's Relationship ('the volume-variance relationship') for the practical situation of a change of support from 5 m vertical blasthole samples to 3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage relationships for a wide range of cut off grades. The experimental test indicated that, given a representative histogram and variogram, the DG change of support provides a computationally efficient and practical means of reliably assessing global mineable resources at the early stages of a mining project. Further, it allows a range of selectivity strategies to be meaningfully and comparatively considered prior to mining.

Jan 1, 1995

By B Saunders, J Carpenter

PanAust’s Phu Kham copper-gold operation (Phu Kham) in Laos is currently limited by throughput in the Semi Autogenous Grinding (SAG) mill. The ability to accurately predict SAG mill throughput (throughput) is therefore critical to accurately forecast copper and gold production. During the fourth quarter of 2016 the proportion of hard unweathered rocks in the mill feed increased, resulting in a period of lower than expected throughput. These low throughput rates prompted a study with the aim of identifying a practical solution for throughput predictions. The study identified an empirical modelling approach based on actual SAG mill throughput rates. The empirical model was then optimised by linear programming to identify the ideal feed blend of unweathered rocks to achieve a maximum SAG mill throughput.Rock strength was the initial focus of the throughput study at Phu Kham because previous studies had identified a strong link between rock strength and throughput. It was determined that there was insufficient valid data to adequately model but sufficient data to qualitatively characterise rock strength. The data identified that the weathering and lithology had a controlling influence on the rock strength. Complicating throughput predictions were operational improvements (changes to blasting and mill settings) implemented in response to the lower than expected throughput. This created uncertainty with the throughput equations. A self-learning empirical modelling method was developed to predict the throughput by incorporating fundamental rock properties with operational practices and improvements. The method is based on the proportion of mill feed with similar weathering and lithology (a proxy for comminution performance) and the actual mill throughput using the SAG mill as the analytical instrument. The modelling method simultaneously incorporated the sum and interaction of unmodelled influences including blasting, crushing and mill settings. The empirical modelling method worked at Phu Kham because the lithology and weathering has an intuitive and observable controlling influence on SAG mill throughput. The modelling method is described along with a worked example of feed blend optimisation using linear programming.CITATION:Carpenter, J and Saunders, B, 2017. Empirical mill throughput modelling and linear programming for blend optimisation at the Phu Kham copper-gold operation, Laos, in Proceedings Tenth International Mining Geology Conference 2017, pp 291–296 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

The underground coal mining industry in Australia has, in the last 30 years, undergone a revolution in production methods, techniques and results probably unparalleled elsewhere in the world. It can lay claim not only to leading the fight against pneumoconiosis and setting high safety standards generally, but has at the same time recorded comparatively high rates of increase in output per man shift. The latter has been achieved as a result of progressively matching the latest in production and underground transportation equipment with significant changes in seam development and extraction techniques and the introduction of stress-relieving extraction methods unique to the world scene. However, the seam recovery factor is still too low. Apart from the overall objectives of maximising production and commercial returns with the greatest safety, there must be a concentration towards maximising seam recovery, particularly in high seams. The search will continue for systems which are more completely continuous mining operations than the present stop-go operations, with longwall having long term potential in this regard, but as yet not sufficiently developed to engender confidence for its more general use. Techniques developed in the last 10 years make the development and extraction of deeper seams, perhaps to 2500 feet or more, feasible with continuous miners as well as longwall. The future will see a greater use of continuous shifts at mines, larger mines with more sophisticated management organisation, extensible belts at the face, better systems of immediate roof support at the face, remote operation of face equipment, greater use of roof bolts and the longer roof cables. With commercial confidence in coal mining now virtually assured to at least the turn of the century, the stage is set for heavy capital development in the industry which will undoubtedly include major research into the whole area of mining methods and equipment. We must ensure that our contribution to such research equitably matches other coal producing countries.

Jan 1, 1975

By R Zhang, X Huang, M Zhou, X Lv, C Bai

Iron ore sinter accounts for a large proportion of blast furnace ferrous burden in Chinese steel mills. Depleting high-grade iron ore resources and spreading complexity of iron ores in mineralogy and morphology have made it more difficult to utilise iron ores efficiently and economically. In this paper, the physical properties of iron ore particles were characterised using mechanical sieving, laser sizing and gas adsorption. From those measurements, two physical indices (fractal dimension of the particle size distribution and surface morphological factor) are defined as important variables for optimising the granulation performance of iron ores. The moisture capacity and the contact angle of iron ore particles with water were also measured to determine the strategy of water-feed in the granulation process. It can be concluded from the experimental results that an increase in the fractal dimension of the iron ore particles will lead to a better granulation performance, while an increase in moisture capacity with a range of 12.8 ~ 14.8 per cent would increase the optimum water content where the granule packed bed achieves its best permeability. Furthermore, the optimum permeability varies inversely with the moisture capacity of the sinter mixture.CITATION:Huang, X, Lv, X, Zhang, R, Bai, C and Zhou, M, 2013. Iron ore characteristics and their application in optimising the granulation process, in Proceedings Iron Ore 2013 , pp 261-268 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By J Li

Cannington Mine has been developing through paste backfilled stopes since the year 2000. These paste drives have been used as either production drill accesses or long-term bypasses. Prior to this study, the ground support requirements for each paste development cut were: an initial 50 mm layer of fibrecrete, weld mesh bolted with 2.4 m split sets, followed by a second coat of 50 mm fibrecrete. Both layers of fibrecrete and the layer of mesh were to be installed before the next cut could be bored and fired. This support regime proved successful at Cannington, however, the total cycle time for each cut was lengthy due to the installation and curing times associated with each layer of surface support. In an effort to reduce the cycle time a study was carried out, with the aid of RocScience’s Phase2 numerical modelling software. The modelling reviewed all of the parameters controlling the stability of a newly excavated development cut. The parameters studied included the early strength of fibrecrete, the ground support load capacity, and the strength of the paste fill masses which varies depending on the cement content. As a result of the study, the ground support standard was revised. The revision has significantly decreased the cycle time as well as fibrecrete consumption, all the while maintaining the safety of personnel and equipment.

Mar 21, 2011

By Y Xu, T Rowles, B Dareeju, A Dissanayake

Recent updates on tailings dam design guidelines require analysis of undrained (short-term) stability with the application of the SHANSEP model. The SHANSEP model, which was originally developed for alluvial soils, predicates that the Undrained Shear Strength (Su) increases with increasing effective stress. Residual soils by their nature do not necessarily follow this relationship. This paper examines an alternate method to define Su over a range of effective stress conditions for residual soils. Residual soils, formed by weathering of their parent rocks, are generally micro-structured in nature. The microstructural features, such as interparticle bonding, play a fundamental role in stress-strain behaviour of the residual soils. As interparticle bonding is independent of effective stress and void ratio, the undrained shear strength of residual soils is expected to be less dependent on effective stress than alluvial soils, especially at low stress levels. A series of triaxial tests conducted on residual soils, however, indicated that the undrained shear strength and the undrained shear strength ratio (Su/σv’) are to a degree dependant on effective stress. It was found that the undrained shear strength ratio is significantly higher under low stress levels and progressively reduces with increasing effective stress. Based on the laboratory testing data, a strength function with varying undrained shear strength ratios can be developed for the residual soils under the stress range anticipated for a design of a tailings dam. This includes capping the input undrained strength at lower effective stresses based on the drained (effective) and minimum undrained strength. The Factor of Safety (FOS) calculated for the embankment utilising the traditional limit equilibrium (LE) method indicated the application of undrained strength function for the residual soils can provide a significant optimisation for the embankment design compared to adopting a constant undrained shear strength ratio or constant undrained shear strength in the design.

Jul 1, 2021

By J Harmse

This paper deals with the modernisation of the brakes on an electrically coupled Blair multi-rope hoist and covers the removal of the old calliper brakes and hydraulic control system, and its replacement with brake discs, disc braking units and hydraulic control systems. The paper covers the braking requirements of the hoist, which is made up of two electrically coupled single-drum hoists, together with the theory behind the choice of brakes and control systems supplied. The paper also covers the project logistics that were required in order to install and commission the new brakes and control systems with the minimum disruption to production on the only rock hoist on a major production shaft. Items covered include the modifications to civil works, pre-installation of bearing lubrication systems, brake discs and hydraulics and the interfacing of the new hydraulic control system to the existing electric control system. It had to be designed to be compatible to a new electric drive and control system due for installation at the end of 2005.

Jan 1, 2005

By D R. Seaman, Y Peng, F Burns, D J. Bradshaw

Telfer Gold Mine is a gold-copper mine in the eastern Pilbara of Western Australia, owned and operated by Newcrest Mining Limited. TelferÆs ores are processed by a dual train, 21 Mt/a, concentrator where gold is primarily recovered by gravity concentration and the flotation of a gold-bearing copper concentrate. A minor portion of TelferÆs gold is also recovered to a pyrite concentrate that undergoes treatment via carbon-in-leach (CIL) cyanidation. The gold recovery of the CIL circuit is below the industry standard and operates with a high reagent consumption rate.With a new fine-grinding facility, the Telfer process plant will have the ability to liberate copper and gold from the pyrite concentrate and recover these by flotation prior to the existing leaching circuit. This process will improve overall gold and copper extraction, while reducing reagent consumption in the CIL circuit.This article is an overview of the development of this methodology. Size-by-size analysis and mineralogical studies of monthly composites identified factors limiting the CIL gold recovery and the causes of high reagent consumption. Laboratory studies confirmed a relationship between the regrind product size and gold leach recovery. The addition of an intermediate flotation stage ensured that the regrind circuit will improve overall recovery while at the same time reducing operating costs. Without the addition of a flotation stage, the additional reagent consumption from regrinding alone would be prohibitive towards increasing recovery. Pilot scale studies confirmed the conditions required to selectively recover gold and copper from the pyrite concentrate as well as establishing the full scale regrinding energy requirements. Construction of this facility at Telfer is currently underway.CITATION:Burns, F, Seaman, D R, Peng, Y and Bradshaw, D J, 2012. Development of a pyrite regrind circuit at Telfer Gold Mine, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 45-52 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Christie AB

Stream sediment geochemical analyses from 140 mining company exploration surveys of the Coromandel, Northwest Nelson, Marlborough and Westland regions of New Zealand have been compiled from open file reports and entered on a database called REGCHEM (for Regional Exploration GeoCHEMistry). REGCHEM is supported by GEOEXPL, a custom-written computer software application which operates under the Microsoft Access relational database mangement system on a PC-type computer. The data are plotted as maps using the Maplnfo geographic information system (GIS) package. Thesholds separating anomolous values from background values are determined using the PROBPLOT univariant statistical package, which enables the descrimination and modelling of several populations. Relevant REGCHEM data are being incorporated into a GIS for the Coromandel region as part of ongoing studies to sevelop mineral deposit and metallogenic models for the region, and to assess regional prospectivity.]

Jan 1, 1995

This paper reviews the development and operation of a small underground tin mine in NE Tasmania. Tin mineralisation was discovered in the Lottah area in the 1880's with early alluvial and eluvial workings leading to the development of large low grade open pit operations. Apart from short lived activities operations ceased in 1915. Intensive exploration in 1978-81 outlined substantial tonnages of low grade tin mineralisation (0.2% Sn) of open pit material. An underground ore body was also located (800 000 tonnes 0.6% Sn). Spectrum Resources Australia Pty Limited acquired a 98 percent interest in the property in 1988. Mine and mill development began in early 1989 based on an underground mine utilising trackless mining using room and pillar with fill stoping. The milling circuit involves primary jaw crushing, Barmac secondary crushing to lmm, Mogensen and DSM screens with jigs and tables to make a wet concentrate. Final tin concentrates are produced by high tension and magnetic separation. Planned production rates are 500 t/day with a mine life of 6-7 years.

Jan 1, 1990

By Young DJ

Gold mineralisation at the Hamata prospect is related to a series of stacked pyrite and quartz-pyrite veins associated with a number of shears which strike N to NE and dip E. Mineralisation is contained entirely within the Morobe Granodiorite close to the intersection of the Upper Watut Fault and some younger NE to SW striking faults. The prospect was originally detected in 1987 by a regional stream sediment sampling programme. Subsequent mapping and sampling outlined an anomalous zone approximately 900m long by 300m wide. Drill testing has indicated a resource of 46Mt at 0.9 g/t Au.

Jan 1, 1991

By Hayes P. C

The reduction of small, dense zinc oxide (ZnO) samples in CO/CO2, and CO/N2 gas mixtures has been investigated at temperatures between 900 and 1100¦C. The microstructural characterisation of the reacted and partially reduced samples was complemented with measurements of the rates of the reactions. The mechanisms and kinetics of reduction of zinc oxide were found to be dependent upon the CO partial pressure, the oxygen potential of the gas mixtures, temperature and degree of reduction.

Jan 1, 1991

Open pit mines in the Yilgam Craton have unique hydrogeological characteristics resulting from a combination of geology, mineralisation and the complex and extended development of the regolith. The principal features of this geological relationship are:ò deep and complex multi-stage development of the weathering profile; ò steeply dipping rock layering;ò supergene enrichment; andò mining across the regolith/rock interface.These features result in large changes in permeability horizontally across rock layers; vertically through the weathering profile and along-strike in association with mineralisation and the mineralised Structure.

Jan 1, 1993

The hydraulic backfilling of mine tailings has proven very successful at the Homestake Mine in Lead, South Dakota. It allows greater versatility, selectivity and safety in mining. It has also minimized surface subsidence and underground rock movement. The tight filling also eliminates underground fires. This paper explains the hydraulic backfill method used and the problems encountered by so doing.

Jan 1, 1973