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By H Zhang, A Lawrence

To accommodate the fast growing need for services in Singapore’s Marina Bay downtown area, Marina South, the construction of a common services tunnel (CST) was required. The CST includes various services such as telecom cables, power lines and water pipes. A deep excavation and temporary earth retaining system (TERS) was required to facilitate the construction of the tunnels. Marina Bay is reclaimed land over thick soft marine clay which is likely to be still consolidating. The deep soft marine clay poses a big challenge for deep excavations in downtown areas where highways and sensitive structures are close by. This paper presents a case study of part of the CST Phase 1B and 2 at Marina South, in particular a 26 m deep excavation supported by a 46 m diameter temporary caisson. The construction started in late 2006 and the basic structure was completed in early 2011. The caisson was formed by 1.0 m thick overlapping diaphragm wall panels with a capping beam and three ring beams at different depths. Two-dimensional finite element analyses were conducted to predict the ground settlement, lateral displacement, bending moment and hoop stresses in the diaphragm wall and ring beams during different excavation stages. A comprehensive instrumentation and monitoring scheme was established to verify the design predictions, control excavation safety and trigger the contingency plan to protect public safety. The impact of construction activity, unbalanced temporary stockpiles and adjacent deep excavation for a mole removal will be discussed.CITATION:Zhang, H and Lawrence, A, 2014. A case history of a deep excavation in a big circular shaft in Singapore marine clay, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 581–588 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Bioleaching Metals from Waste Printed Circuit Boards and the Shapes of Microorganisms

Sep 13, 2010

The Wattle Dam gold mine, located near Kambalda in the Goldfi elds region of Western Australia has recently progressed to an underground operation and is now believed to be Australia's highest grade operating gold mine. At end of March 2010, the deposit had reserves of 132 000 t @ 20.8 g/t for 88 000 oz and by the end of June 2010 had produced 110 000 oz from open-pit and underground mining. The Wattle Dam main lode is characterised by very coarse gold mineralisation. Gold occurs as cm to decimetre fracture fi ll veinlets, shear surface coatings and erratic fl akey clusters. The gold has no quartz or silica association and lacks adjacent low-grade mineralisation or alteration assemblage. Geologically it appears atypical of Archaean lode gold deposits and may represent an extreme end member of the type. Definition of the lode is largely dependent on effective geological identification of the host lode zone and an understanding of the erratic distribution and grade behaviour of a high-nugget, coarse gold deposit. Dependence on assay data to defi ne the lode zone would result in the deposit being mined incorrectly and much of the deposit being left unexploited. This paper discusses the geology, coarse gold characteristics and defi nition methods which are used to successfully defi ne and mine the deposit.

Aug 1, 2010

By B McCreath

Industrial process water for the Commodore Coal Mine and the adjoining Millmerran Power Station is provided by pumping secondary treated sewage effluent 100 km from the Wetalla Sewage Treatment Plant near Toowoomba. (A separate source is used for potable water.) The effluent is not of sufficient quality for discharge to a watercourse, but it is suitable, with further treatment, for the mine and power station. In designing and constructing the pipeline, special emphasis was placed on preventing accidental spills or planned releases to the environment. The pipeline and associated works can transfer 1000 ML/annum for reuse in the coal mine and power station.

Jan 1, 2003

An Integrated Solid Waste Management Method for Western Macedonia, Greece

Sep 13, 2010

By J Franz, S Bock, N Hentrich

Artificial ground freezing is the unrivalled method for groundwater control during mine shaft sinking. Moreover, ground freezing may also provide temporary ground support. The fast development of fibre-optic temperature monitoring devices, three-dimensional freeze pipe survey methods and numerical modelling software provide grounds for developing new and reliable tools for ground control during freeze shaft sinking. This paper presents examples of predictive numerical models that are based on back-analysis and calibration of temperature data that covers the complete construction cycle from pre-freezing through to artificial thawing. The back-analyses showed that standard numerical models are not capable of predicting the prevailing thermo-mechanical conditions satisfactorily. This paper describes the development and implementation of new tools for improved consideration of concrete hydration and latent heat, along with the introduction of other algorithms that improve and simplify the efforts of managing complex numerical models. A function is presented that allows for an automated correction of the model’s mesh based on results of three-dimensional freeze pipe surveys. This paper demonstrates that the latter consideration is important, because the often employed assumption of idealised freeze circle geometry in numerical models impacts on the accuracy of such model’s predictions. Subsequently, the verification of these extended numerical models is demonstrated. Due to its flexibility, the FLAC3DTM code was employed for the numerical modelling. This software provides the possibility of implementing additional functions written in internal FISH or Python language into the models. It is concluded that state-of-the-art techniques for freeze hole drilling and surveying, on-site monitoring and advanced numerical analysis provide a significant potential for both the design and the operation of largescale ground freezing measures. The application of the extended numerical models for predictive simulations during construction allows for temporary shaft lining optimisation, for assisting in operational decision making and for compensating temporary loss of monitoring data. Suggestions are made for required future work in order to further improve the developed ground control tools. CITATION:Bock, S, Franz, J and Hentrich, N, 2018. New tools for ground control in freeze shaft sinking, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 393–406 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

Ladies and gentlemen, distinguished guests and fellow members of The AusIMM, good morning.   Thank you for the opportunity to address you all today, Crown Minerals are very pleased to be associated with the conference again this year, and I commend the committee on their organisation and delivery of this yearÆs event.   As you can see from the topic of my discussion, I would like to broach the subject of collaboration between ourselves û Crown Minerals û and you our clients, and convince you that we are on the right track but can each do more.

Jan 1, 2007

By P Holtham, K Duffy, B, W Valery, E Tabosa, rade

Pre-concentration has potential to significantly improve Mineral Resource efficiency by removing gangue early in the process, before energy intensive and expensive comminution and fine processing. However, there are numerous options for pre-concentration and the performance and benefits of these are very case specific. To determine the best option for a particular deposit and to successfully integrate it into the overall mining and processing operations requires comprehensive evaluation. This needs to consider orebody suitability, technology capability and economic viability. The in-situ variability of a deposit and how it is influenced by mining methods and the liberation size of gangue are key factors which are generally not well understood. Geostatistical methods provide an insight into orebody variability, and the overall selection of any pre-concentration solution must be an integrated approach between geology, mining and processing. Many pre-concentration evaluations investigate the potential of just one option. Technology selection should start wide and may include: selective mining, pre-screening (with or without selective blasting), sorting (bulk and or particle), coarse gravity separation (e.g. jigging, DMS), coarse particle flotation, magnetic separation, etc. The upgrade performance of these processes is very ore specific and should be determined from testing, with detailed multi-component modelling used to determine the overall process performance. Many of these pre-concentration processes require significant ancillary equipment, feed preparation and materials handling. It is important to realistically estimate all costs to understand overall economics and select the best option. Some examples showing evaluation and comparison of pre-concentration options are presented in this paper. These include assessments of in-situ variability using geostatistical tools, process modelling of pre-concentration options and overall performance, preliminary layouts and cost estimates, and economic evaluations.

Nov 10, 2020

By H R. Phillips

During the 1980s and early 1990s, the South African coal industry experienced a series of methane explosions in which well over 200 coal miners lost their lives. In addition, a fire and an explosion in the gold mining sector claimed a further 240 lives. These tragic incidents resulted in the establishment of a research facility at Kloppersbos dedicated to explosion and fires research and the funding of an extensive research program, and almost certainly influenced the government of the day in its decision to establish, in 1993, the Leon Commission of Enquiry into Mine Health and Safety. The results of this focused research program, the wide-ranging recommendations of the Leon Commission and the determination of the coal mining industry to improve its safety record all combined to result in the past 20 years without a major explosion.This paper lists some of the research outcomes and, through three case studies, illustrates what can be learnt from investigations following explosions. The paper concludes with an evaluation of some of the findings of the Royal Commission on the Pike River coal tragedy. Many of the Commission’s conclusions are pertinent and relevant to the coal mining industry worldwide and their implementation could significantly improve coalmine safety; however, a careful study of the available facts indicates there could well be an alternative explanation of the source of the methane, the location of the ignition and the size of the explosion at the Pike River coalmine.CITATION:Phillips, H R, 2015. Lessons learnt from mine explosions, in Proceedings The Australian Mine Ventilation Conference, pp 19–28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By T Bookless, J Pownell, D Meadows

The ever increasing trend of the gold price has meant that ore deposits that were previously considered too complex, or unattractive by virtue of their low gold grade, are now being investigated more closely. These ore deposits present a greater risk of failure than previously was the case. To ensure that the risk of project failure is reduced and the maximum value is derived from the deposit, its mineralogy, as well as other characteristics, should be well understood such that the optimum process can be designed.Quite often the flow sheet design is assembled using individual process components, from various sources, and without consideration of the complete system. Test work programs require careful planning and an open viewpoint in terms of comminution circuit design particularly with respect to ever increasing power costs across the globe. As an example, high pressure grinding roll (HPGR) technology in many cases offers better mineral liberation than the more traditional comminution devices and it does so at a reduced energy input, and yet HPGR test work is often restricted in its scope due to the perceived novelty of the technology and the resultant lack of generally agreed and accepted test work routes.In this paper the authors outline a typical HPGR test work process route driven by the needs of different ore types and illustrate that to optimise the project value, any test work program should start from the premise that thorough understanding of the ore is vital.CITATION:Bookless, T, Meadows, D and Pownell, J, 2013. Enhancing project value through a designed high pressure grinding roll test work program, in Proceedings World Gold 2013 , pp 291-300 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

Within CRLÆs lifetime there have been a number of products that have proceeded through their life cycles. In each case market forces and technological advances have forced the cessation of the product. The company has then had to develop alternative outlets for its copper. Sometimes it has produced a similar product to fill the same market. In other cases the extra copper is sold as cathode. Today, CRL produces no semi-fabricated copper products and all cathode is sold. More recently, CRL has ventured into the sale of technology and manufacture of cathode motherplates. This area, whilst it is not what had been a traditional area of core business, has been found to be profitable.

Jan 1, 1998

It is a great honour to be privileged to address The Institute for a second time as President and I appreciate it more than I can say. Eight years ago in Hobart I tried to cover the development of the mineral industry in Tasmania. That was a general subject. Tonight I want to be more specific - I propose to talk to you about rutile.The choice of subject for a Presidential Address is never easy. One is addressing an informed audience and the best one can do is to try to crystallize a particular subject and to present it in a form that willbe of interest to those who listen.I looked carefully at the addresses given by our Presidents over the past seven or eight years. The titles are impressive, the content excellent, and the length, as published, much greater than I had hoped.It is therefore with some trepidation that I have chosen as a subject one only of the three crystal forms of titanium dioxide. This subject is not as limited as may at first appear.There are two aspects with which I can deal - the mineral itself, which has become familiar as the major product of the East Coast beach sand operations, and the lesser-known "synthetic" product, which is the major pigment in almost all the white paints in common use today, and in cosmetics and white-walled tyres and toothpaste, and even the better types of fine papers. The synthetic form of rutile is' the "whitest"of white pigments.

Jan 1, 1966

By C De-Vitry

In skewed distributions seen in many geochemical data sets, samples at the extreme ends of the distribution are often termed ‘outliers’. Samples considered as outliers can often make exploratory data analysis and resource estimation more difficult and less reliable. Such outlier samples may be legitimate because they are part of a natural high- or low-grade tail in the distribution. How these samples are identified and dealt with in resource estimation can often be a material issue for the Competent Person, particularly under the latest edition of the JORC Code (JORC, 2012). This paper discusses the identification and characterisation of outliers and high- and low-grade tails and proposes methods to deal with them in estimation.For dealing with outliers and high-grade tails ,very simple approaches, such as top-cutting through to more advanced geostatistical approaches, are discussed. The strengths and weaknesses of each approach are also outlined. Some examples of how the underlying geological understanding of a deposit influences the view of outliers and low-/high-grade tails is provided. The importance of documenting, communicating and challenging a given geological model is also discussed. Finally, some ideas for dealing with the uncertainty created by outliers are outlined.CITATION:De-Vitry, C, 2014. Identifying and dealing with outliers in resource estimation, in Proceedings Ninth International Mining Geology Conference 2014 , pp 159–168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By N Clarke, J Hunt, A Barros, L Keeney

The Gramalote orebody is a large low-grade gold deposit situated in the San Roque municipality, 124 km north-east of Medellin in Antioquia, Colombia. It is jointly owned by AngloGold Ashanti (AGA) and B2Gold and is currently in Feasibility Study phase. In 2013 AGA requested CRCORE to undertake a preliminary study of the potential application at Gramalote of pre-concentration by screening, part of the Grade Engineering suite. 160 samples of coarse assay rejects (-3 mm) were tested and showed one of the strongest responses seen worldwide to that time, suggesting that about 70% of the gold could be recovered into 40% of the mass. This was seen as potentially markedly improving the Gramalote economics. A large-scale testing program was implemented on site to follow up these results. A total of 18 samples of 17 t each were mined along a pre-existing exploration adit. A complex test flowsheet allowed size fractions to be generated from the as-received material as well as after crushing to 53, 23 and 3 mm, all from the same head sample. The procedures were designed after carrying out a heterogeneity study to measure sampling errors. The coarser size fractions were designed to study the effect of crushing on upgrade response and predict the response on open-pit run-of-mine ore. The finer size fractions were designed to investigate means of predicting the upgrade response across the orebody. The large-scale testing closely confirmed the average upgrade response as predicted from drill core assay rejects but found that only the -53 mm crushed material accurately predicted the upgrade response of individual samples. Ore geochemistry was able to usefully distinguish samples with good and poor response. A small study on drill core suggested that, for Gramalote, fine crushed material distinguishes vein associated and disseminated values but not other factors that control actual outcomes.

Nov 10, 2020

In this paper, the scientific bases of creation of simulation modelling systems of excavator-truck-conveyor complex work are represented. During the simulation modelling process of big mining and transport systems work the strict and full account of an order and sequence of all operations of simulated process is carried out. Step-by-step fixing of mining and transport system elements condition - excavators in loading and unloading points, trucks, road section, unloading points in storage bin, crushers and conveyors is conducted. Work and idle time of system elements are considered. During modelling process the information characterising system work as a whole is collected. It allows us to establish qualitative and quantitative influence of each system element on the final results of its functioning and provides to estimate rationality of a particular organisation variant of mining and transport equipment interaction from technological positions. Simulation results are: economic and technological indicators of mining and transport complex functioning of the period for each subsystem, as well as on the road, the points of loading, unloading and reloading.

Dec 6, 2010

THE art of mine surveying has made very great progress in recent years, and is still advancing, perhaps faster than any other branch of surveying. The scope of the mine surveyor's duties has greatly increased, his instruments and methods have improved, the responsibility of his position is greater, and the end is not yet in sight.It might be supposed that such a steadily growing subject would have an adequate literature, but this is by no means the case and outsiders commonly judge mine surveyors by their text-books. Hardly any condemnation can be too strong for most of these books. The English books truckle to the antiquated and crude methods apparently still in use in England, and thereby largely aid in perpetuating them; they commonly in illustrative examples give the distances in fathoms, feet, and inches; they spend page after page discoursing on instruments that should have been forgotten long ago; they try to antagonize theory and practice by detailing such calculations as that a certain vein will contain 2,003.907 pounds of galena per square fathom, and then reduce this amazing quantity to hundredweights, quarters, and pounds. Nothing can be more unscientific, or, for that matter, less businesslike, than unwarranted assumptions of accuracy; it is, perhaps, the greatest curse of applied science. Here we have a calculation to thethousandth part of a pound, when there is probably an unavoidable error of two hundred pounds. What shall we say of a man who explains how to measure the depths of shafts to the hundredth part of an inch by means of short brass rods screwed together...

Jan 1, 1909

By B Taylor, S Evans

Bulk explosive technology for underground mining has not seen any significant technological advances since the widespread transition from ammonium nitrate fuel oil (ANFO) to ammonium nitrate emulsions (ANE) commencing in the 1980s. The in-hole energy profile that conventional ANE systems deliver is limited by the physics of chemical gassing and simple control systems. This compromises the range, precision, and accuracy of energy delivery into the blasthole, and in some cases limits the length of charge that can be delivered. Orica’s 4D™ bulk system removes many of these constraints, enabling better blasting performance across all underground mining methods. This paper reviews work completed at three mining operations across Australia, the United States, and Chile with a focus on how this system can improve mining operations and deliver sustained commercial and productivity benefits into the future. These benefits include improved ore recovery, reduced dilution from waste rock, and reduced overall explosives consumption. This paper also reviews how this new technology can be applied for planning future mining operations.

Sep 1, 2024

The Martha deposit is an economic giant epithermal gold deposit, with mined and unmined resources of more than 218 000 kg (7 Moz) Au. The Au-Ag, base metal sulphide-bearing quartz lodes in the Martha deposit form an extensive braided pattern within hydrothermally altered andesite wall rock. There are five main quartz lodes: 1.      Martha, 2.      Welcome, 3.      Edward, 4.      Empire, and 5.      Royal.   Information from historic mine plans and reports has been used to determine the depth distribution of economic ore within the Martha deposit. Economic ore (average of 10 g/t Au) in the Martha underground mine was at a maximum width and strike length between a vertical depth of 160 and 350 m. Below this depth the quartz-sulphide lodes continue, but the grade declined to sub-economic grades (< 4g/t Au) at about 575 m depth and economic ore shoots were localised, mainly on the hangingwall side of the lodes. Samples from exploration drill holes indicate that this decrease is associated with a depth zonation from electrum-bearing Zn-Pb-Cu-Ag sulphide ore (average 10 g/t Au) to sub-economic (< 2 g/t Au) electrum-poor Zn-Pb sulphide mineralisation.

Jan 1, 2006

Mineral exploration and mining in New Zealand has had almost five years of new legislation. The requirement for different consents is a challenging, time consuming, expensive exercise but in most cases the new procedure is working, although the matter of obtaining access to land is still a major issue. Priority is critical. After lodgment of an application for a minerals permit there are many other matters to address such as identifying land owners, occupiers and administrators, preparation of access applications, consultation and preparation of various resource consent applications.

Jan 1, 1996

By R Osterman

As mining companies have to go deeper in search of ore and coal, the importance of protecting the highwall increases. Wall fatigue also increases with importance of the long life expectancy of a highwall, in particular the impact of fatigue influenced by resonance. Resonance is the tendency of a material to oscillate with greater amplitude at certain frequencies when exposed to a periodic force. Until recently, only dominant frequencies, either natural or induced, were all that could be measured through the fast Fourier transform of the blast-induced wave form.This paper presents a novel method to accurately predict the resonant frequency of a highwall. In fact, the method can predict the natural frequencies between any two monitoring points placed in line with the source of impact, and as such it can be used to determine the resonant frequencies of any physical object. The method not only predicts the resonant frequencies of the material; it predicts the structural response of the total frequency spectrum. This method helps describe the response of a mechanical structure to excitation. It describes the structure’s efficiency in the use of energy, that is, whether energy is dampened or consumed in resonance.The initial predictions have been so accurate that it made it possible to determine the fundamental frequency and the first six harmonics of a highwall in a northern Queensland coalmine. With the use of electronic detonators, the blast can be timed with a repeating delay to create an induced artificial frequency that has been determined to retain the least amount of energy.CITATION:Osterman, R, 2015. Transfer function – new method to accurately predict resonant frequencies of a highwall, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 233–244 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015