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By H M. Ahmed, W S. Dunbar

Construction of cave mining systems requires significant capital expenditure and long-term commitment of human, equipment and material resources before production commences. Risks and uncertainties of these large-scale mining projects are significantly higher than for small-scale projects. This is due to the complexity and interactions of the construction schedule components and the large scale and uniqueness of such projects. One way to successfully manage construction uncertainties that would lead to schedule delays is to include a reasonable cost contingency in the budget estimation. A real options approach based on the least-squares Monte Carlo (LSM) method is used to estimate cost contingency associated with schedule uncertainty in mass mining projects. Cost contingency is estimated as the cost of potential project crashing (acceleration) decisions, which pays for not extending the schedule. While such a significant undertaking is expected to be subject to some delays, these can have an enormous impact on the economic value of such projects. The value of the crashing option was explicitly formalised into the process of valuation, as it is assumed to be a single option being considered in the valuation at every decision point prior to the construction completion date. As a part of the proposed method, a stochastic function for the percentage of remaining scope of work for the remaining duration of the entire project was integrated into a framework of numerical simulations. This ensured that this function can implicitly account for sources of schedule uncertainties for projects represented by multiple and overlapping work packages. The LSM method was applied to a real case scenario in an operating block cave mine, with modified scale and features. The results yielded by the LSM method indicated that significant changes in capital budget allocation stem from variation in a contractor’s risk perception and confidence level of estimated delays.CITATION:Ahmed, H M and Dunbar, W S, 2016. Budget estimation and contingency allocation of block cave construction using least-squares Monte Carlo real options, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 801–808 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Electrochemical Behaviour of Massive Chaclopyrite Bioleached Electrodes in Presence of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus In this work, the monitoring of bacterial and chemical dissolution of massive chaclopyrite was evaluated using cyclic voltammetry (CV); the mineral surface was examined using scanning electron microscopy (SEM) and the elements were examined by Energy Dispersive X-ray Analysis (EDAX). The electrolyte employed for the electrochemical tests was the medium used to bioleaching the electrodes (3.0 g/L (NH4)2+SO4, 0.5 g/L K2HPO4, 0.5 g/L MgSO4+7H2O and 0.1 g/L Ca(NO3)2).The results showed differences in voltagramms carried out by Acidithiobacillus ferrooxidans and Acidithiobacillus caldus: In bioleached electrodes tested in the presence of Acidithiobacillus ferrooxidans, the anodic and cathodic current signals were larger than with Acidithiobacillus caldus. The analysis of CV results allowed attributing the different peaks observed in both the direct and reverse potential scanning to the oxidation of chaclopyrite to a secondary copper mineral (bornite, chalcocite and covellite) and its reduction via different non stoichiometric copper sulphides intermediaries. Surface evidences were observed by SEM, and chemical elements evidences were also investigated by EDAX.

Sep 13, 2010

By A Kemp, I Taylor, S C. Lamoureux

Detailed landform designs were completed for six (integrated) iron ore waste rock dumps at a Western Australian iron ore mine site to meet closure objectives and to optimise material movements for closure. The designs were based on specific physical and geochemical properties of waste material and the design was undertaken to enhance long-term stability of the dumps and optimise material movements, and therefore minimise closure cost. Construction of the re-shaped waste rock dumps have been completed. Following construction, surface material characteristics were found to deviate from those used in the design assessment. Materials present at surface following re-shaping were generally finer textured than those sampled for modelling. It is anticipated that the embankment slopes may experience increased rates of surface erosion compared to the rates predicted from modelling and used in design. The finer textured material is thought to be generated from exposing finer material that has migrated into the coarser matrix over time or that was not present in the sampled top surface of the landforms. This is due to armouring processes over time and this phenomenon is likely to recur following further wet seasons. The majority of the waste materials present in the waste rock dumps were subgrade banded iron formations (BIF) and chert, which are generally competent and geochemically inert. Some waste material was known to have an elevated risk of erosion but present in relatively small quantities. The presence of a large number of dolerite dyke swarms indicates appreciable volumes of dolerite were produced as waste from the pits. This material has an elevated risk of being highly erodible/dispersive. Clays and shales are also likely to be present in the dumps and are considered to be less competent material (relative to the BIF/chert). This paper presents the process from upfront materials assessment through detailed design to construction of the rehabilitated waste rock dumps, and post-construction sampling and testing to validate model findings.CITATION:Kemp, A, Taylor, I and Lamoureux, S C, 2017. Design to closure – construction of detailed rehabilitation designed iron ore waste rock dumps based on upfront site specific assessment, in Proceedings Iron Ore 2017, pp 353–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By R Battison, R Duggan, S Esen, K Henley, P Dare-Bryan

Increased catch bench crest loss has been observed in recent years at Barrick’s Cowal Gold Mine situated in central New South Wales, Australia. A project was initiated to diagnose the cause of the crest loss, and evaluate ways to limit its effect on final walls.A range of different blast measurement techniques were utilised to evaluate the progressive damage caused to catch berms by presplit, production and trim blasts. Techniques employed included; single point vibration measurement, cross-hole seismic analysis, precision berm surveys, horizontal p-wave velocity measurements, crest loss volume calculation and water level changes between blasts.Blast measurements showed that the majority of damage to the catch berm was caused by the presplit blasts, which registered vibrations greater than 700 mm/s at 5 m behind the presplit line. As a result, considerable changes were made to the blast designs after a series of computer simulations via mechanistic blast modelling (MBM). The uncharged presplit collar was increased from 2 m to 4 m, and every second hole was left uncharged. Vibration modelling using a multiple seed wave (MSW) model was used to optimise trim blast delay timing. Burden relief was changed from 16 ms/m to 27 ms/m using one hole firing per 4 ms time window, and the initiation angle was changed from shallow to steep. These changes in the presplit loading and trim timing helped reduce catch bench crest loss by 1–2 m.Trim shots using a high strength bulk emulsion explosive were also identified as contributors to berm damage after analysis of blast monitoring and MBM modelling. The modelling study resulted in the generation of alternative blast designs to minimise the crest loss, including the use of low-density/low-velocity of detonation (VOD) bulk explosive product (Flexigel™ Advantage) in trim pattern designs. This was trialled on the Northern and Eastern pit walls to evaluate the damage to catch berms on final walls. The trials demonstrated that berm vibration was reduced significantly; fragmentation was similar (or slightly blockier) compared to the fragmentation using the old blast designs; displacement of the berm was reduced, so increased catch bench widths were attained. This paper summarises the trials, and presents a summary of the crest loss to date.CITATION:Battison, R, Esen, S, Duggan, R, Henley, K and Dare-Bryan, P, 2015. Reducing crest loss at Barrick Cowal Gold Mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 189–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

While I contemplate the formidable catalogue of bodies and organisations participating in this Conference and the impressive array of qualifications chalked up after the names of the representatives I am indeed honoured to be invited to address you. When I consider the theme you have chosen for your conference I am also somewhat daunted: "The Twenty First Century - Mining for Mankind". It is indeed dramatic, challenging. But what, I ask myself, can a mere KCMG say to all you professional fellows and doctors and academicians? It is not for me to stray on to the more esoteric areas that you will be covering, thereby running the risk of teaching my grandmother how to suck manganese nodules. On the other hand it seems to me that you deserve more than the courtesies, not to say banalities, that are sometimes - sadly, and unjustly - regarded as the stock in trade of diplomats.

Jan 1, 1986

Gentlemen, you heard the good Doctor has commissioned me to make a'summary of the proceedings to date and also to close the said proceedings. It seems that over the years the business of making a summary alternates between'Mr. Pearce and myself, also I,think that w~oever is around onthe day in question 'obtains the task and apparently I drew it this, year. It is hoped you will be patient as previous experience in this capacity'indicates that the best way to proceed is to have a brief summary on each paper and then do a summary of summa~ies. This makes the approacha little cumbersome but it is felt to be fair to each author and it brings'back to the audience some recollections of what transpired at the time and they can make their own decisions, which may not necessarily agree with those of the 'sum'marisor.

Jan 1, 1983

Modern, research-based approaches to mineral exploration are essential to the future maintenance of the mineral industry. These need to fully utilise the rapidly expanding growth of understanding of the evolution of the earth's crust, and be properly integrated with advances in understanding of chemical and physical processes involved in ore formation. BMR has a major role to play in supporting the growth and utilisation of this research base, as well as maintaining the national geological and geophysical bases which are essential both to tactical and strategic interests of Australia and of its mineral industry. The objective development of data-process modelling is one target of such strategic research based on a more integrated approach to research by BMR, mineral companies, CSIRO and the universities with emphasis given to promoting positive feedback during research activities. Examples of the success of strategic research in Australia and overseas are noted in the Text.

Jan 1, 1986

By Shanahorn C

During the last decade the proper training of operating and maintenance staff has been recognised as directly contributing to the successful startup and continuing operations of a metallurgical project. During this period Bechtel has assisted clients in the design, development and implementation of such training. The clients have been located in Australia, Papua New Guinea, Africa, China and North America. The programmes have addressed mobile and fixed plant operations and maintenance in coal, copper, gold, borax and other mining environments. The level of sophistication has varied from highly structured and documented instruction to less formal, yet controlled efforts to reorient and enhance the skills of experienced workers to training personnel with no previous work experience. Many lessons have been learned, some easier than others. This presentation will recount the elements of various projects which enhanced and detracted from the cost-effective achievement of the goals which training was

Jan 1, 1986

By P Murthy, Z Guan, P Townson

In this paper, we introduce a methodology to optimise mining equipment operation in terms of the conflicting concerns of productivity and availability. We also introduce the concept of damage points and equipment dutymeters. These provide the mine management with tools to monitor the success of such optimisation. Since we have quoted the results of an on-going Australian Coal Association Research Program (ACARP) project, the apparent focus of this article is on draglines. However, the concept is equally applicable to other equipment. Mining is the type of business that requires a large investment in capital infrastructure and equipment to produce a product that is sold at a relatively low unit cost. In such a business, the key to competitiveness lies in achieving the full realisation of capital investment ie sustained production at high levels. Some of the concepts outlined in this paper are essential components of this picture.

Jan 1, 2000

The Prospero orebody is a part of the Helene mine at Cosmos and was scheduled to begin production in March 2008 after the exhaustion of the Tapinos orebody in the same mine. Treatment of the Tapinos orebody was challenging and it was envisaged that Prospero would have similar properties given that it was also anomalous in deleterious elements and would be of a similar mineral hosting. It was deemed necessary to undertake a metallurgical test work program to identify any potential processing issues, complex mineralogy or significant metallurgical domains. The paper discusses the processes which were employed to undertake the metallurgical test work program and describes the aspects that can be employed by other developers to quickly and effectively assess potential future orebodies. It will demonstrate that the work was successful at determining expected metallurgical behaviour, providing direction for mining operations and highlighting areas for more extensive research.

Jan 1, 2009

It is a privilege for me to participate in this vitally important discussion of The Role of Governments in the Management of Resources. The distinction of my fellow participants is evidence that this event is a matter of extreme importance and attracts international attention. In the management of natural resources, government and private enterprise share awesome responsibilities for the economic well-being of nations. Mining and its relation to the prosperity of nations is almost as old as recorded history. Copper was being mined and extractive metal- lurgy practised at Timna in Israel's southern desert as far back as 4000 B.C., and the rich mines of Laurium not only saved the Greeks from Persian domination 2500 years ago, but also provided Athens with a monopoly of silver in the Mediterranean world. This bolstered the economic power of Athens and led to the golden age of Greek commerce and culture.

Jan 1, 1978

By A Domanti, C Jewkes

This paper describes the design and constructability issues investigated in the selection of a trenchless solution in comparison to trenched construction options as part of a scoping study for the augmentation of the existing Bulimba Creek Trunk Sewer in Brisbane. Initial work involved the planning of alignment options vis-a-vis ground geology, geotechnical conditions, location and depth of shafts considering potential construction technology, flotation and stability of the tunnel, availability of construction sites and the influence of construction works on neighbourhood properties and the immediate environment. Two design pipe sizes, DN1200 and DN1500, were considered, and factors including jacking forces, specification of product pipes, pipe joints, pipe jacking methods and the associated impacts of ground settlement were carried out. Of particular interest was research on suitable lubricating fluids with the potential to minimise jacking forces and maximise the length of pipeline between launch and reception shafts.

Jan 1, 2008

By Ely K. W

On January 21, 1986, a methane ignition and subsequent mine fire occurred in the under- ground workings of the Jim Walter Resources, Incorporated No. 3 Mine located near Adger, Alabama. The fire, which began on a longwall face and eventually spread into the adjacent gob area, could not be extinguished directly and raged out of control for several hours. Sealing operations were begun underground by Mine Rescue Teams and the fire area was successfully sealed with the mine able to resume production in about one month. The No. 3 Mine liberated over sixteen million cubic feet of methane in twenty-four hours. The operation was unique, in that, the successful underground sealing of a fire in an ultra-gassy mine had not been attempted or com- pleted for several years. Maps and charts are included to give explanation of the typical data used to manage the recovery effort.

Jan 1, 1988

By Coxhead B. A, Brandt B. A

The geological exploration and evaluation of coal reserves involves the appraisal of very large amounts of data. Computers afford an ideal means of handling and manipulating the data, thereby avoiding the laborious and expensive method of manually compiling the logs in full descriptive language. The Minad system of computer storage and retrieval of geological and analytical data is particularly suited to the description of cores and cuttings from exploration drill-holes. The encoded data is arranged in a 120-column computer output sheet format; descriptive geological information in a 54-column geolog and analytical information in a 64-column assaylog. The acquired data is quantitative, uniform and relatively complete and can be selectively retrieved for processing by a wide range of specialized computer programs developed for the coal mining industry. Visual retrieval of data for manual processing is facilitated by the use of simple codes and logical word abbreviations.

Jan 1, 1977

By Anylmore M, Walker A, Fletcher A

Roasting of sulphide and sulph-arsenide gold ores produces unwanted emission of sulphur and arsenic oxides, and a less than complete recovery of gold. Pyrite loses sulphur and arsenopyrite loses arsenic at a useful rate at temperatures of 600¦C and above in an inert atmosphere. Sulphur and arsenic driven off can be condensed before entering the atmosphere. During the process, solid-solution gold redistributes itself on internal surfaces of the resulting iron sulphide. Two subsequent processing options may be used; direct cyanidation of the porous sulphide resulting from the anoxic pyrolysis, or a second-stage roast to oxidise the remaining iron sulphide. The first option may be viable under certain conditions of pyrolysis. The two-stage option has an environmental advantage over the traditional roast because it reduces oxide vapour emissions by 50 per cent. The second stage may provide nearly enough energy to sustain the entire process.

Jan 1, 1992

Large scale open pit mining at Ok Tedi and Misima are described in this paper. The paper also presents the socio-political problems encountered in the construction, operation and waste disposal of high technology, high output gold and copper mines in very remote and rugged terrains. Despite these handicaps, mining companies from all over the world have established top class mining facilities including huge open pits, underground mines and mineral processing plants to extract rich mineral deposits of gold, silver and copper.Papua New Guinea is the sixth largest gold and copper producer in the world. New projects likely to come on stream before the end of this century would make it the world's third largest gold producer. The mining industry is the largest organised industry in the country employing over 10 000 persons and investing over US $1000 million on these mega projects per year.

Jan 1, 1992

By Hellsten K, Eshuys E

The best long-term approach to exploration involves the use of extensive quality data and the integration of many different factors, methods and techniques. The successful exploration manager needs to integrate people, area selection and exploration methods, with the use of descriptive and genetic geological models. Based on a syn-metamorphic genetic model for Archaean gold, successful exploration in Western Australia requires the integration of data on anomalous gold, alteration, lithology and structure. Many other parameters such as geophysics, geochemistry and regolith studies provide additional, indirect information that needs to be integrated into the overall exploration programme. Timely access to research findings and ability to integrate these into immediate exploration has contributed considerably to the success of the gold industry in Western Australia since 1980. Extensive and deeper drilling, and the ability of computers to handle the volume of data generated have enabled effective testing of many more geological targets.

Jan 1, 1996

By Jones JJ

A laboratory study of size segregation is described using a model of a Paul Wurth hopper industrailly employed for blast furnace charg- ing purposes. Experimental charge materials used in the study were glass ballotin.i (1-4mm dia.) and sinter fines (0.25-4mm). The tracer material employed consisted of coloured glass beads. The results of the study show that the discharge stream from a Paul Wurth hopper is characterised by an initial negative segregation followed by a positive segregation and that this segregation pattern is a property of the hopper geometry and the filling conditions. A simple computer model based on experimental tracer concentration results is proposed. The measured segregation results and those predicted by the model show close agreement. Application of the results with special reference to the effect of size segregation on charge permeability in blast furnaces is also included.

Jan 1, 1984

An analysis of pumping figures suggests that there are two distinct styles of water inflow patterns in Zambia's mines. Carbonate hosted orebodies (Kabwe and Nampundwe) display a characteristic seasonal variation in water inflow with peak pumping showing a short time lag with respect to the rainfall pattern. Aquifer characteristics are controlled by secondary, weathering enhanced, near surface phenomena. Non-carbonate hosted orebodies such as those of the Copperbelt (Konkola and Nkana) occur in successions of highly variable lithology and consequently there are stacked aquifers of variable character. Inflow of water does not display seasonal variation. The major factors affecting the amount of inflow are the structural setting, the geometry of the orebody and the local lithostratigraphy. Thus the Konkola orebodies which occur in a saddle shaped open ended basin result in what is probably the wettest mine in the world, pumping some 376,000 cubic metres of water a day.

Jan 1, 1988

The operation of quarries for the production of crushed stone and aggregates, depends heavily on rock blasting efficiency, which usually represents a major share of total production costs. After investigating the causes of this situation, a series of technical aspects have been detected, and they are described for the purpose of contributing to the minimization of costs, which also reduces the effects of blasting on the environment. Utilization of empirical design methods, of inadequate explosive types, and of erroneous drilling pauems with respect to rock properties, are the main factors to be corrected, as a consequence of poor engineering criteria, with scarce use of computational methods and field instrumentation. Several concepts of blasting optimization are pointed out, and their application to industrial operations in a Portuguese limestone quarry indicated clear trends for the reduction of production costs, as well as some of the deleterious consequences of blasting on the environment.

Jan 1, 1990