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By Barnett DW

Financial risk analysis provides the tools to examine the uncertainty of capital decisions in new mining ventures. This paper explores the methodology by which financial risks can be studied and quantified. The most commonly used risk evaluation methods, such as sensitivity analysis and discount rate adjustment, are presented as an introduction to a more comprehensive discussion of stochastic methods of discounted cash flow analysis using Monte Carlo sampling. The discussion is illustrated with examples of a stochastic discounted cash flow. The advantages of Monte Carlo sampling in risk analysis are discussed together with its problems, particularly those originating from the correlation amongst the variables that determine the economic output of a mining venture, and the difficulties created by insufficient data, imperfect knowledge and complexity. The paper also surveys the most commonly used software used in risk analysis.

Jan 1, 1994

By Wardle L, Wright G

This paper describes the investigations and results of monitoring of deformations of houses located within the area of influence of a pillar collapse over the Westfalen No. 3 coal mine near Ipswich, Queensland. The subsidence resulted in minor subsidence of at least 18 modem houses and serious damage to 4 others. The history of the events and the measures taken to deal with the physical problems arising are described. The investigations and results are described and related to the mining methods and geology. The stability of coal pillars up to 9.6 m high was considered and computer modelling undertaken to relate surface subsidence to estimates of the extent of pillar failure. Assessments were made of the likely extent of subsidence during the incident. Measurements of distortion and tilt were obtained as the ground slowly subsided and criteria established to determine when the structures were deemed to be unsafe. Detailed surveys of houses affected or anticipated to become affected were also undertaken. Four houses were condemned and subsequently demolished as a result of excessive tilt. The methods of assessment are described and the implications of the results related to the various' house designs.

Jan 1, 1992

Different mineral structures can act as mineral reservoirs for the immobilisation of toxic compounds. In the paper different mineral structures will be explained and their potential for incorporation of heavy metals and anions will be shown. The following structures will be explained (P÷llmann, 2007):apatites (incorporation of heavy metals, silicate apatites);ettringites (fixation of oxo-anions);layered double hydroxides (fixation of heavy metals, fixation of anions, fixation of organics, sorption materials); andmanganese oxides. Different possibilities of solid solution and incorporation in crystal structures will be explained and advantages of stable minerals be proved using experiences with real toxic wastes. In the process of thermal treatment the formation of primary mineral reservoirs will be shown. The precursor phases (similar to well known cement minerals) react in contact with water to form secondary mineral reservoirs (cement hydration mineral products). The formation condition of primary and secondary mineral reservoirs and their stabilities and incorporation possibilities will be shown. Examples for incorporation of various elements are given. Application for water clarification will be outlined.

Jan 1, 2008

By Richardson G. W, Yap L. C

Friction rock stabilisers (FRS) are steel-based, thin-walled tubular ground reinforcement widely used in underground mines in Western Australia. Following installation these stabilisers are subject to corrosion which may reduce the load carrying capacity and lead to unexpected ground falls. Although corrosion has been recognised as a common occurrence, particularly under aggressive mine water and mineral conditions present in underground mines, the knowledge of the effects of corrosion on the mechanical behaviour of FRS is limited. The Department of Minerals and Energy of Western Australia has conducted a laboratory based program of studies to investigate the effect of corrosion on the mechanical properties of FRS. The studies have focused on the effect of corrosion on tensile strength of FRS and frictional resistance along the interface between FRS and the drillhole wall. The results indicate that under certain conditions corrosion damage can significantly reduce the effectiveness of FRS.

Jan 1, 1996

By Bukeikhanov D. G, Syedin V. F, Sagyngaliyev K. S

The present paper describes a method of simulating deposits of com- posite structure by means of computers. The method employs mathematical tech- niques to study the openworks zone formation dynamics in open-pit mines with any mode of the works front ad- vance as well as to determine, on oriented graphs,the optimal direction of openworks expansion.

Jan 1, 1977

By M Brewster

Goldfields Abosso Goldfields Limited (AGL) is a Ghanaian registered company that owns and operates the Damang Gold Mine. Gold Fields Ghana Holdings Limited holds a 71.1 per cent interest in AGL. The Damang concession held by Gold Fields Ghana Holdings Limited covers a total area of 271 km2 located 40 km north of the town of Tarkwa in the south-western part of Ghana. Gold Fields as a company registered on the New York Stock Exchange is legally obliged to be SOX (Sarbanes-Oxley). Sarbanes-Oxley Section 404 (SOX404) is on management assessment of internal controls. The Mineral Resource Management (MRM) function of AGL manages three Prospecting Licenses and two mining licences. At least ten pits/prospects are scattered along the two limbs of the Damang Anticline and have two main types of mineralisation notably Paleoplacer and Hydrothermal. Thus SOX404 procedures are put in place to treat each mineralisation type in the best way for reliable resource outputs and estimates. Generating auditable resources for AGL is a prime but most important function of MRM. Thus important checks are built and designed to ensure that all relevant geological and geostatistical inputs conform to procedures outlined under SOX404 requirements. More importantly sign offs are designed to ensure that technical personnel involved in all aspects of resource and reserve generation are satisfied and can be held accountable.

Jan 1, 2007

By Bacigalupo-Rose

Simulations of complex physical phenomena, such as hurricanes and fluid flow around space vehicles, can now be effectively explored using modem visualisation techniques which have been developed to examine the results of numerical modelling using supercomputers. These techniques are also being applied extensively in medical investigations, including viewing the interior of the human brain. We have now applied these same techniques to the visualisation of gold deposits.Grade control in open pit gold mining operations may involve the collection of at least half a million samples in each mine. Extensive drilling programs also accompany the early reserve evaluation stages and exploration in advance of mining. Maximum utilisation of these very large amounts of information requires an ability to integrate, examine and present large three-dimensional data sets in order to be able to derive and effectively communicate information on grade distribution and geological controls.

Jan 1, 1993

Our ultimate resources come from the Sun and the Earth System. At this time we face a world crisis in energy, water and soil resources. Global pollution problems are increasing in almost all nations. There is an urgent need to use our vast knowledge with a new wisdom and this requires new integrated teams of experts to provide the best alternatives for the needed new development problems. These teams must include economists, engineers and a broad spectrum of scientists. Today it is possible to produce clean energy, stop soil erosion, clean water and reduce and use wastes of many types.

Jan 1, 1995

By Ghose AK

Design and selection of support systems for longwall faces call for in-depth know- ledge of strata mechanics and in particular of strata-support interactions. The paper presents the results of field investigations and analysis of a difficult-to-cave roof using powered supports under a massive dolerite sill in Central India using a state- of-the-art datalogger system. The mechanised long wall face was equipped with 4/680 tons chockshields operated on the IFS mode using a 300 KW DERD shearer. The datalogger system was capable of storing data simulta- neously in 32 channels. The paper describes the monitoring system and the monitoring programme. The system provided useful information on support behaviour, build- up of leg pressures and face convergence during an intense dynamic periodic weighting phenomenon which destroyed the integrity of almost half of the face supports. At this point, the face had advanced by about 197 metres from the barrier. The paper outlines a post-mortem analysis of this dynamic event and provides a critical evaluation of the data collected for understanding strata support interaction and the behaviour of the massive sill in the overburden.

Jan 1, 1992

By T Mizuta, D Ishiyama

The Vienna Wood hydrothermal is hosted by mid-oceanic ridge type basalt in graben morphology and is located in the Central Manus Basin. The hydrothermal field is about 300 metres in diameter and consist of a sulphide mounds and tall huge death and active chimneys. From the three distinct ore types collected from the Vienna Wood site, the dominant ore minerals recognised are pyrite, wurtzite, sphalerite, chalcopyrite, Fe-oxide and gangue minerals of anhydrite, gypsum, barite and silica. The consistencies in the paragenetic sequence and in the spatial distribution of the sulfides across the three ore types suggest that similar hydrothermal process exist across active and death chimneys. Fluid inclusion studies reveal a homogenisation temperature of 190-260¦C and an average salinity of 5.1-5.4 wt per cent NaCl equiv. The pH of the hydrothermal fluid ranges from 4.2 to 6.1. Bulk chemical analyses indicate that the mineralisation in the Vienna Wood can be classified into the Zn-(Cu-Pb) type of mineralisation. The tenors of the ore and mineral assemblage resemble those of the Mid-oceanic ridge system and ancient ophiolite hosted massive sulphide deposits of Cyprus and Oman.

Jan 1, 2002

Average annual growth in consumption of primary energy in Australia over the past 10 years has been 5·5 per cent compared to a world average of 4·1 per cent.Over the next 10 years growth rate is expected to increase to 6 per cent per annum due largely to the rapid development in the mineral processing industry.By the end of the 19705 natural gas is expected to supply more than 9 per cent of Australia's primary energy market. Coal will supply 40 per cent and petroleum products 47 per cent. Nuclear energy will make its appearance but will make only a small contribution in the period.Australia has adequate reserves of natural gas and coal to supply its needs in the 1970s and beyond. However the newly developed reserves of crude oil, while supplying 60-70 per cent of requirements in the initialyears, will need regular and sizable additions if they are to keep pace with the expanding consumption. For Australia to become self sufficient in the period 1970-1990 it is estimated that new discoveries will need to approximate ten times the volume of recoverable reserves found in Australia to date.

Jan 1, 1971

By MacLean L

In 1975 the Commonwealth Government established import parity pricing for all liquid hydrocarbons discovered after the 16th September, 1975. These discoveries were termed "new oil" to differentiate them from existing discoveries and production. Overnight the price of the product being sought trebled, resulting in greatly enhanced economics by increasing the potential returns on existing prospects and by making smaller plays economically viable. After 18 years of drilling, the offshore Gippsland Basin has attained a moderate level of exploration for a basin of its size. Fifty seven prospects have been drilled within the basin but only a few of these were drilled along the southern and northern margins, while the deep water areas along the eastern margin have remained virtually undrilled following the Hapuku-1 oil discovery. The major hydrocarbon accumulations within the basin are trapped beneath the Latrobe Unconformity surface and exploration has largely concentrated on this single play in areas immediately adjacent to the major producing fields.

Jan 1, 1982

By P K. Banerjee, S Kumar

Indian iron ores with less than 62 per cent Fe are currently unexploited, except for a few sectors which export them to foreign countries. It is anticipated that by 2012 the countryÆs domestic steel production is likely to rise to the tune of 60 million tonnes per annum. To meet this requirement, it is necessary to utilise not only the existing high-grade deposits but it is also necessary to look into exploiting the leftover iron ores of lower grades. Hence, reserves with Fe content 62 per cent and below (particularly the ores with In the present paper, an attempt has been made to beneficiate three different types of low-grade iron ores selected from three different parts (states) of the country. In the paper, alternative routes for beneficiation and effective utilisation have been tested using different techniques in the laboratory in an attempt to match their (Al2O3/SiO2) ratio after thorough characterisation and liberation studies. The paper also encompasses the geological formations, occurrences and distribution of Indian iron ores as well as highlighting the problems associated with the fines, possible metallurgical routes, and their market segregation from the perspective of end users.

Jan 1, 2007

This paper will be a discussion of the geological exploration and drilling carried out on the Mt Davy Block, Greymouth Coalfield. A brief summary of the geology of the Greymouth Coalfield will be given to put the Mt Davy Block into perspective.

Jan 1, 1979

This paper details successful implementation of a revolutionary pit access system involving excavation of an 'in-the-wall' ramp at Three Mile Hill open pit operated by Gold Mines of Coolgardie, formerly Goldfan Limited, at Coolgardie, Western Australia. Three Mile Hill is a medium-size, open pit, gold operation typified by hard, competent, fresh rock conditions from near surface. The project involved construction of a haulage tunnel or decline access located in the wall of an open pit in place of a conventional pit access ramp. Works undertaken as discussed herein included excavation, support, ventilation, dewatering, services installation, commissioning and monitoring. Prior to implementation, the conventional hardrock pit slopes and designs were constrained by the presence of infrastructure and a main road to the North and by adjoining leases to the Southeast. The combination of these factors and economic considerations resulted in a decision to proceed with an innovative in-the-wall ramp access system that is believed to be the first of its type in Australia. Back-analysis indicates that implementation resulted in a cost saving of as much as A$3.6 million and increased mineable pit reserves. The paper deals with the successful implementation and operation of the in-the-wall ramp haulage as well as an economic evaluation that is aimed at drawing some general conclusions on favourable conditions for implementation in other mining scenarios.

Jan 1, 1996

By D Craw

The Hyde Macraes Shear Zone is a mineralised low-angle shear within the Otago Schist traceable for ~30 km with a NW strike. It is been actively mined along 12km of this strike, producing >6 Moz of gold. The shear zone consists of greenschist facies rocks with a mineralogy only subtly different from that of the host schist. Pervasive fluid flow has occurred along grain boundaries and within microshears which have been enhanced by the deposition of hydrothermal graphite. We model the development of these microshears using a threedimensional numerical code. For an inhomogeneous initial rock with lithostatic fluid pressures and a dynamic permeability deformed under dextral non-coaxial flow, deformation is distributed into weak shear bands. Graphite deposition and associated reaction-softening has a dramatic effect on the development of model shear zones. Graphite is deposited into a shear band, weakening it and further localising the deformation into that shear band, producing an anastomosing and interconnected shear zone structure such as observed in the HMSZ. The degree of graphite precipitation and graphitic-induced weakening are varied in the models. More graphite precipitation with a low degree of reaction-softening results in more diffuse shear bands. In contrast less graphite deposition but with a high degree of reaction-softening more leads to the development of more focused shear bands. Graphite deposition has clearly controlled the formation of the HMSZ structure, and is an important indicator of potentially mineralised structures elsewhere.

Jan 1, 2007

Production from a major, deep orebody requires the construction of two 6 m diameter, 1000 m deep ventilation shafts over the next three years. Further ventilation upgrades have foreshadowed an additional 1500 m of 6 m diameter shafts beyond that. After reviewing the construction alternatives it was decided to raisebore the first shaft in one pass using Western Mining Corporation's 121R raiseborer and the Wirth sequential head. The significant cost and speed of construction potential of 6 m raiseboring justified the risks associated with this new technology. Large diameter sequential head raiseboring has only been carried out in South Africa. Over the last three years many lessons have been learnt and the technology has progressed to being considered feasible. Operating practice and the optimisation of raiseboring performance for specific ground conditions are the areas requiring further work. The development of large diameter raiseboring in South Africa and the site preparation and initial operation at Z.C. Mines are described. Comment on actual operating experience includes the geotechnical investigations, the raiseborer foundations, cuttings disposal and the drilling of the pilot hole which has progressed to beyond 450 m. Unforeseen difficulties with the verticality of the pilot hole and with mud losses illustrate the types of problems that can be expected.

Jan 1, 1988

By JSrvinen A, Yll÷ E

At Cominco's Zinc Refinery at Trail, British Columbia impurities are removed from zinc sulphate electrolyte by a two-stage purification process using zinc dust. Copper, cadmium and thallium are removed in the first stage whereas cobalt is removed in the second stage. Cobalt removal kinetics are affected by soluble antimony and copper additions to the electrolyte. This study was focused on the kinetics of cobalt removal by zinc powder cementation. Experimental variables included copper and antimony concentrations, pH and temperature. Common organic additives employed in zinc plants were studied to determine potential interactions with the cobalt removal process. Cementation products obtained from laboratory experiments and plant practice were studied using SEM. A number of significant results were obtained: 1. Copper and antimony ions were sustantially removed from solution during the early stages of the cementation reaction (within the first 15 minutes). Cobalt cementation kinetics are slow and follow a first order kinetic regime. 2. A drop in the cobalt removal rates can be correlated with a rise in the Eh of the slurry. 3. Ligninsulphonate, Percol 351 and animal glue at levels of 2 mg/L significantly impede cobalt cementation.

Jan 1, 1993

This paper will discuss the challenges and opportunities in the years 1998 to 2002 faced by the operation and personnel at Thalanga, and its continued survival through short life projects (three feasibilities in four years). It will describe the processing of the different ores, issues faced and operating and technical innovations that occurred during that period. This will include: commissioning on very high grade Cu ores, treatment of high Sulfur feed ores (~46 per cent S) and the effects of the installation of a Detritor Mill on the process.

Jan 1, 2003

Maximising margins in today's competitive international commodity markets demands superior productivity. This requires more than simply selecting the best equipment. It requires efficient production and commercial processes together with management systems recognised as international best practice. This paper introduces an integrated way of working that includes management systems for successfully changing work practices and attitudes, developing managers and increasing accountability. It provides an improvement methodology that includes systematic involvement of people in true continuous improvement of processes for maximising productivity and safety while minimising costs. Even though the principles are proven in all industry sectors worldwide, they are not always used correctly. This paper provides examples of traditional performance measurement systems to show how managers miss opportunities to control and improve both production and supporting service processes. It also describes the basic methodology for correct use of the principles and provides examples of correct implementation of modem systems in mining. The charts from actual mining case studies will be elaborated upon in the conference presentation. This paper's main aim is to provide background material for the presentation by introducing integrated principles for building best practice management systems for superior productivity and safety - for higher margins.

Jan 1, 1996