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By Aspinall T. O

This paper discusses the identification and assessment of risk for mining developments particularly for open pit mining. A distinction between sensitivity studies and risk analysis is developed, demonstrating the importance of geological and mining engineering judgement -as applied by experienced practitioners to the analysis and assessment of risk in such projects. Technical and financial risk analysis are discussed under: ò mineral resources and ore reserves; ò mining and processing methods; ò project construction; ò financing; and ò costs and commodity pricing predictions.

Jan 1, 1994

Much of the data required for the evaluation of mine design is obtained from bore cores. It is essential to collect data that is useful and not to overlook features which might have adverse effects upon the mining practices and which might not be readily discernible to the untrained eye when examining bore cores. Interpretation of the data has progressed from the use of single-value properties, such as ultimate compressive strength or Young's modulus, to the utilisation of most measurable quantities. The simulation techniques used employ physical and mathematical models for prediction of mining conditions or strata behaviour. The application and capabilities of these methods to mine design are discussed.

Jan 1, 1977

By West R

Since its introduction in 1989, the Australasian Joint Ore Reserves Code (the JORC Code or the Code) has been one of the success stories of the informational interface between the mining industry and investors. This is due variously to the user-friendly nature of the Code itself, to its practical approach to this complex subject, and to the way in which its requirements have been implemented in practice. Recognition of its utility and effectiveness has influenced a significant number of mining countries to re-assess their reporting standards with the positive outcome being that for the first time, a set of standard international definitions for reporting of mineral resources and reserves is a realistic possibility.

Jan 1, 1996

Gallery Stoping, an old but little used stoping method, has been reintroduced to workings at the Paringa South Shaft.Orebodies which are amenable to such a method are being mined in this manner with considerable advantages and savings.The advantages of gallery stoping as used at Paringa, compared with traditional mining methods are:1. constant cash flow2. low set up cost and initial stope development3. nearly 1005 recovery 4. no access problems 5. quicker tonnagesAs compared with highly mechanized mining methods, it has been found to be slower but requires less development, gives improved grade control, has less impact on the surrounding rock and fragmentation is much better, reducing secondary blasting costs.This paper examines the mining method and illustrates the advantages of gallery stoping at Paringa.

Jan 1, 1985

In a coal mine there are many substances capable of ignition under certain circumstances, which can be placed in the following groups: ordinary combustible solids, dusts, liquids and vapours, gases, metals and plastics. There are many factors influencing ignition, including temperature, minimum ignition energy, particle size, explosion pressure level, rate of pressure rise, specific energy content and also explosive limit. Not all are applicable in every case. Frictional ignition of methane is an accident statistic of increasing concern and is considered in some detail. Practical measures that can be taken to reduce the incidence of frictional ignitions are considered, and also possible ways of ignition suppression.

Jan 1, 1981

By Govett G. J S, Currie D. A, Cohen D. R

Analysis of mechanical size fractions of soils around the Paddington deposit (W.A.) and the Charters Towers Goldfields (Queensland) shows a bimodal gold distribution, with enrichment in the coarsest and finest fractions; this is probably a common feature of soils in arid terrains. To establish the true distribution of Au within the soil fractions, the effect of bulk Au content and percent weight variations in size fractions can be reduced by a normali- zing procedure. The greatest extent of lateral dispersion of Au recorded in the -125 ¦m fraction at Paddington and the -63 ¦m in the Charters Towers area as compared to the coarser fractions, and increas- ed levels of sample representivity in the finer fractions, favours their use in exploration. If orientation studies indicate the preferen- tial use of coarse or intermediate fractions, only wet sieving can quantitatively dis- aggregate the clays and remove finer contamina- ting material. The collection of extremely fine fractions such as the -63 ¦m is also accelerated by wet sieving. The additional costs of wet sieving may be offset by better interpretation of results through increased analytical sample representivity, anomaly contrast and continuity.

Jan 1, 1988

The mineral sands industry in Australia can contribute much more sig- nificantly to economic development beyond the year 2000 by increased production of constituent minerals such as ilmenite, zircon, rutile, leu- coxene and monazite from existing and new resources, and especially from downstream processing to intermediate and finished products based on these resources. The end-use areas for mineral sand-based products include those products whose demand is tied to general economic growth, such as paints and plastics, and refractory bricks for the steel industry. High techno- logy applications such as zirconia ceramics and super-magnets are indica- tive of new developments in technology which provide considerable scope for expansion at higher rates than overall western world economic growth. An optimistic outlook for the industry is outlined, based upon a brief review of opportunities.

Jan 1, 1988

There are a number a stages in a project at which an audit must, or should, be undertaken. An independent audit may be necessary for the comfort of directors and/or financiers before the major finance is committed, but an internal pre-development audit is the opportunity for the management team to take stock of the project and reaffirm their confidence and commitment. Maxims for project success are given and a check list for pre-development audits is presented. The need of mid-development audits may arise and their brief will depend on the circumstances arising. A game theory approach to decision-making is demonstrated in which the alternative of fast-tracking a development is considered. At the conclusion of the project, before the team is disbanded, a post-development audit should be made. Valuable learning can come from this process which could give important guidelines for future projects and a check list is presented.

Jan 1, 1997

A thick sequence of alkaline intrusions and volcanic rocks underlies a Quaternary caldera on Liliir Island. The sequence is host to a still active sub-aerial hydrothermal system and associated epithermal gold mineralisation. Sub-horizontal alteration horizons exhibit progressively increasing chondrite norma-lised (La/Lu) en and (La/Sm) cn ratios from unaltered shoshonites, to the potassic alteration zone, to the argillic altera-tion zone to the advanced argillic alte-ration zone. The increasing fractionation of HEE, and especially of LHEE, up the alteration sequence is the result of de-creasing pH, temperature and alkalinity of the hydrothermal fluids with increa-sing alteration intensity. HRE3 were especially mobile in argillic and advanced argillic alteration units characterised by acid fluid conditions and large fluid volumes. Abundant Cl, S and CO2 within the hydrothermal fluids and thus abundant REE complexing agents and large fluid volumes favoured the mobility of REE during hydro-thermal alteration of the volcanic rocks and intrusions. Steam escape, mixing of the gases with groundwater and a change from a magmatic neutral chloride hydro-thermal system to a meteoric acid sulphate system was accompanied by liquid/vapour ratio changes, pronounced alkalinity, pH and temperature decreases, and fluid/rock ratio increases. This caused the mobili-sation, fractionation and deposition of PF.F.

Jan 1, 1990

The process of establishing the design criteria is the key step in commencing a new project.. The method for establishing design criteria and translating them to a workable plant design is described. INTRODUCTION The use of activated charcoal to recover gold from alkaline cyanide leach liquors is the most rapidly expanding technology in hydrometallurgy today. The process, known as carbon-in-pulp (CIP), has replaced countercurrent decantation as the method for recovering gold by cyanidation. Carbon-in-pulp entails mixing activated charcoal with a ground ore-water slurry containing gold cyanide, allowing the charcoal to adsorb the gold, and then mechanically removing the gold loaded charcoal from the pulp. The pulp is sent to tailing disposal and the loaded charcoal is sent for gold bullion production. Activated charcoal's affinity for gold has been docu- mented for over one hundred years. In the first cyanide plants, one of the preferred methods of stealing gold was to place a piece

Jan 1, 1982

By Kister H

Hoesch HUttenwerke AG, Dortmund, West Germany, is an integrated steel work of the Estel-group. The nominal annual production capacity-is about 7 Mio tons of steel. Hoesch has along experience in operation of diffe-rent types of slag granulation plants and of utilization of the granulated product. This experience is used to granulate a large amount of blast furnace slag and to process it in own cement plants and produce blast fur-nace cement.

Jan 1, 1979

By Mostyn G

In the last three decades various theories have been presented to allow the estimation of the force required to cut rock. These have generally relied on an hypothesised mechanism of chip formation.The paper presents results of an experimental program completed on an unjointed artificial rock in which the force and chip geometry were measured during deep cutting with a quarter scale bulldozer tyne. The program included various depths of cut and artificial rock of varying strength. The experimental results are compared with predictions based on three expressions for cutting force. Generally the measured forces are within the range of those predicted but none of the methods predicts the cutting force with any accuracy. It is considered that the discrepancies are due, in part, to the fact the that actual shape of the chip formed in deep cutting is quite different to that assumed in developing the theories and thus the theories cannot be expected to predict the cutting forces. It is concluded that Evans and Nishimatsu's theories predict lower bound estimates of the horizontal cutting forces. Deliac and Fairhurst's approach appears to over estimate the forces required to cut rock. New methods of prediction are required based on the observed mechanisms of failure.

Jan 1, 1993

By Newman D, Wyslouzil DM

Different conventional and non-conventional flowsheet configurations were examined for the treatment of a number of refractory lead-zinc and copper-lead-zinc ores containing carbonaceous pyrite, flotable non sulphide gangue and pre-activated zinc. The flowsheet configuration for the processing of complex massive sulphide ores has a remarkable effect on the overall metallurgical results. Conventional sequential flowsheets, with circulation of intermediate products for both lead-zinc and copper-lead-zinc ores, gave poor metallurgical results and often saleable concentrates were difficult to produce. The concept of semi-bulk flotation and double bulk flotation with coarser grinding of the ore, followed by single or double-stage regrinding and sequential flotation was established to be most effective in achieving optimum metallurgical results. This flowsheet design gave superior results as compared to the conventional sequential flowsheet, and resulted in a lower reagent consumption, a significant reduction in the circulation load of intermediate products, and improvement in the rate of flotation of valuable minerals. Thus, optimum flotation conditions were provided for different products within the flowsheet.

Jan 1, 1993

Before any accident prevention and total safety programme can succeed, a safety concientiousness or attitude needs to be implanted in the employees' minds. Psycholog- ical and physiological conditions play a vital role in accident causation and prevention. Both need attention in a good safety programme, but working place conditions and environment are more easily corrected. However, the challenge is to change attitudes in the minds of men - psychological factors in accidents. To do this does not require a Safety Officer, but does require a Safety Adviser. At Blackwater mine a Safety Adviser is available to all sections of the organisation to guide and assist, to provide data and material to use at meetings, to help in accident investi- gations and to help organise training. To eventually achieve total commitment requires every member of the management team to be a salesman towards all around selling an attitude to safe working, a way of life. At Blackwater mine the workforce is young overall with most employees being under 40 years old. Psychologically this is a quite different problem to a balanced ages working group. A great deal of effort is needed to communicate with the younger, articulate, better educated employee who is also generally a skilled operator in the capital intensive

Jan 1, 1975

A geologic, petrographic and geochemical study has been performed on the pyroclastic flow deposits in the coastal area of East Zhejiang Province, Southeast China. This study leads to classification of the pyroclastic flow deposits into three associations: the extrusive type, the surge type and the ash flow type welded tuff associations. Through detailed investigation and comparison of the characteristics of these lithologic associations, with emphasis on the welded tuffs, a comprehensive model has been proposed to demonstrate the petrogenesis of the pyroclastic flow deposits.

Jan 1, 1995

As part of a prefeasibility study being undertaken by Newcrest Mining Limited, the Cadia East Implementation Team has developed an access decline to the proposed underground operation. This paper describes new technologies that have been employed in this development, which include: high frequency drifters that have penetration rates one and a half times that of competitors, ensuring minimal increase in drill time, despite rounds greater than 5.5 m;automated drilling used in conjunction with laser navigation and face pattern design software, which facilitates exact positioning of hole collars, lengths and lookouts for accuracy and repeatability; andemulsion charging that reduces manual handling; has variable string loading capabilities, via its hose retraction system, for perimeter control and reduced fume characteristics. A Six Sigma improvement process was used to support the system change undertaken and demonstrated that development rates improved 60 per cent above the comparable single heading benchmark.

Jan 1, 2008

The Southwest Pacific is a region of active volcanism and geothermal systems. Only in New Zealand have the geothermal systems been exploited for electricity generation and industrial processing. At present, approximately 280 MWe of geothermal electricity is generated in New Zealand. A considerable amount of further exploration work is required before the total geothermal potential of the region can be assessed and before the significance of these resources can be judged against other local energy sources.

Jan 1, 1990

By H R. Phillips

Fresh air intake in an underground coal mine is of critical importance to the occupational health and safety of workers due to the dynamic, confined and dangerous nature of the mining environment. In most coal mines in South Africa, belt road is not separated from the fresh air intake to the sections. Intake air to coal production faces generally contains dust generated by conveyor belts, transfer points and travelling roads. Long roadways (up to a few kilometres in some of the existing mines) to the coal sections are involved in the ventilation circuits of individual sections. This leads to a progressive increase in the dust levels in the intake fresh air and thus high dust levels in the air delivered to the working sections downstream. In the process of reducing worker exposure to dust in the face area, attention to the monitoring of fresh intake air is generally given a low priority. This paper summarises the intake dust levels measured in selected South African underground coal mining sections over the past five years and its use as a parameter in assessing worker exposure to dust through a newly developed model called the Dust Exposure Level Index (DELI). Based on the measured data of the South African coal mines, the average section intake dust level was 0.78 mg/m3. Approximately 60 per cent of the samples collected for the study have exceeded the 0.5 mg/m3. The intake dust level measured at a longwall face was much higher than in the CM headings. The measured section intake dust levels furnish the South African coal mining industry with the latest depiction of the level of face area dust contamination due to the intake air. Further, this paper demonstrates the use of intake dust level as a parameter in estimating exposure levels of workers, as it clearly plays as a corner stone in effective control of exposure to face area respirable dust. It must be borne in mind that intake dust is a base level to the mine worker exposed to dust without carrying out any additional work in the section. If the intake air is seriously contaminated by airborne respirable dust; then the exposure of the workforce in the section will constantly be elevated by that background dust level.

Jan 1, 2005

By S Kodate, Ö Aydan, Y Suda, J Tomiyama

Fracture zones are commonly found in the Earth’s crust. These zones may cause very severe engineering problems. Therefore, the formation and the assessment of the mechanical characteristics of these zones is of great concern for rock engineers. A new double shearing jig was used to study the formation of shear zones in rock under static and impact loading conditions using the device developed by the authors. A series of experiments were undertaken to investigate formation on the formation and characteristics of fracture zones in laboratory. Although actual fracture zones are more complicated, various tests give some insight view of the formation of fracture zones as well as some information on their mechanical behaviour under both dynamic conditions and static conditions. The authors report the outcomes of these experiments and discuss their implications in practice.

Nov 29, 2022

Project managers must juggle many aspects to bring their project in on time, on budget, and in accordance with the aims of the project owner. Whether the project is a mining feasibility study, a technology implementation or a construction project, it falls to the project manager and his or her team to deal with risk from two standpoints, which may be at odds with one another. First, a project team must deal with risks to the project itself û that is, risks to on-time, on-spec and on-budget delivery against the value promise made to the customer. Second, there is the management of risks within the subject matter of the project, undertaken on behalf of the customer. The project manager cannot dodge this responsibility; yet there is a tendency (particularly in smaller, in-house studies) to avoid digging too deep, possibly for fear of what may be uncovered! This paper investigates the responsibilities of project teams in regard to risk management and reporting. It examines ownership of project risk; the nature of risk management activities undertaken by the team during the course of a project; and outlines some controls to ensure that the two opposing arms of project risk are reconciled for the benefit of both the project team and the project owner.

Jan 1, 2007