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By Turner WG, Short RR

Obviously, the paramount advantages of contract mining have been recognised by mine developers throughout Australia, as evidenced by surface gold mining operations of significant output almost exclusively being performed under contract. These paramount advantages of using an experienced professionally managed contractor result from the mine developer being freed from financing the required relatively large capital expenditure at current relatively high interest rates or in a capital scarce stock market, and from the need to recruit and sustain a large operating work force in a competitive labour market.

Jan 1, 1990

Equity finance provides the most suitable and frequently the only access to capital during the exploration and evaluation stages of resource projects when project risk is at its highest. Investors are prepared to provide equity funds in the knowledge that they are compensated for the higher risk they take on with higher potential returns or sufficient upside potential to justify the higher risk. The context of resource projects which determines the role of equity finance has changed considerably. Prior to the resurgence of the gold price and the development of new mining technology many resource projects were selectively mining orebodies by underground methods frequently with limited reserves proved up in advance of mining. The limited proved ore reserves base and the volatility of the gold price all contributed to a higher risk and higher return investment environment in which the use of equity finance was more appropriate and frequently the only option for capital raising. The financial risk of a resources project can be transferred to an underwriter who makes the commitment to distribute the financial risk between a number of investors. There is also the opportunity for financiers to use a mix of equity and debt finance to allow a company to proceed with the development stage where without such a mix the resource project would not proceed. By using a level of equity finance the project becomes robust enough in its ability to service the debt finance facility and the project proceeds with the equity participants receiving a suitable risk reward return. The liquidity from the establishment of a market for the company's securities enhances further capital raising and generally enables the company to satisfy its financial requirements on more favourable terms particularly during bull markets. The role of equity finance in the management of the financial risk during the exploration, evaluation, development and mining stages of resource projects is summarised in Table 1. In more detail the principal roles of equity finance and the ways in which equity finance impact on the risk management of resource projects will be considered in turn.

Jan 1, 1994

An approximate rapid design system for tunnel liners and underground structures is presented which permits the effects of structure geometry and stiffness, rock quality in terms of its deformation modulus, and the applied system loading to be entered as data to produce direct designs conforming to stress limitations, optimum reinforcement requirements and restraints on section dimensions. An 'equivalent column' concept is introduced for modelling the rock mass in contact with the structure. Only the rock treatment is given in detail but the results of sensitivity analyses, with reference to rock quality, for a typical liner design are given and these results related to a number of empirical design approaches.

Jan 1, 1976

By X B. Sun

Mining work is a high-risk operatation under a special environment. It is affected by space, lighting, noise, vibration, dust, air pollution, etc as well as coal seam conditions, complicated geology construction, combustion of coal, gas, coal dust, etc. Factors which affects safety production are numerous, eg natural conditions, technical equipment level, producersÆ and managersÆ qualities. It is a complex system engineering to ensure mining safety and high efficiency. Among the ideology, methods and measures of safety management are the most important factors besides safety technology. Mine productive environment is a main problem that affects minerÆs work as far as safety and health are concerned. Combining ChinaÆs mine productive environment situation and using human ergonomics theory, this paper explores a series of measures and suggestions as to how to reinforce safety management, how to build up the safety management ideology, how to improve the mine production environment, how to decrease coal mine accidents, and how to ensure mining safety and high efficiency.

Jan 1, 2003

By P Christen

The Ernest Henry Copper gold mine situated in North West Queensland, Australia, is owned and operated by Xstrata Copper. Currently the open pit produces 11 Mtpa of ore. With open pit mining ceasing in mid 2011 development has begun on an underground sublevel cave mine to extend the life of the operation by another 12 years. When completed the open pit will be 530 m deep and 1.5 km in diameter. The orebody dips at approximately 45° and has been outlined a further 450 m below the base of the pit. This provides some challenges for the Ernest Henry underground mine which is designed to initially truck development and production ore from the end of the pit until a hoisting shaft is commissioned in 2013. Production will then increase to 5.0 Mtpa on its way to an ultimate rate of 6.0 Mtpa in 2016.This paper will focus on the capital development and infrastructure requirements for the underground mine. Areas covered include mine accesses, ore handling system, accommodations for the dip of the orebody, primary ventilation design, dewatering systems and selection of an underground workshop over surface only maintenance.Discussions include the complications arising due to the mine being located directly below a large open pit and the combination of first principle cost analysis and risk assessment which has been used to safely optimise the feasibility study designs.

Mar 21, 2011

By R H. Sibson

The gold province of Otago occupies an area of upwarped basement, the Otago Schist, comprising predominantly quartzofeldspathic and volcanogenic metasediments. This assemblage is the product of collisional tectonic deformation and associated metamorphism, mainly to lower greenschist facies, during the Rangitata Orogeny (200-100 Ma). Historically this region has produced 240 tonnes of gold, 4% (10 t.) of which was from the mining of Cretaceous goldquartz mineralised vein systems. Auriferous vein systems in the Otago Schist are mainly hosted within NW trending normal fault-fracture arrays, however NW trending reverse fault-hosted vein systems also occur. We propose that the Late Cretaceous-mid Tertiary Otago Schist structure represents a regional anticlinorium containing flexural folds of at least two wavelengths. The anticlinorium structure has been quantified by determining variations in angular discordance between schistosity and the Otago Peneplain, a Late Cretaceous-mid Tertiary erosion surface covering most of the Otago district. A structural model for the evolution of the post-collisional anticlinorium requires the cooling surficial zone (carapace) of a retrograding metamorphic belt to behave as an elastic lid. Erosion of topographic load on the carapace drove isostatic uplift, which was greatest in the tectonically thickened core of the orogen. In this way differential uplift produced flexural deformation in the elastic carapace, expressed as a large scale arching of the orogenic belt. Flexure created tangential longitudinal strains in the outer-arc, leading to extension and the formation of mineralised normal faults. These structures are separated by a neutral surface from shortening and associated mineralised reverse faults in the inner-arc. Our structural model predicts that the distribution of auriferous lodes should be localised about zones of maximum flexural curvature, where the tangential longitudinal strains are highest. As a result, NW-SE hinge regions separating schistosity dip domains in the Otago gold province may have new found significance as potential exploration targets.

Jan 1, 1995

By Sibson RH

The gold province of Otago occupies an area of upwarped basement, the Otago Schist, comprising predominantly quartzofeldspathic and volcanogenic metasediments. This assemblage is the product of collisional tectonic deformation and associated metamorphism, mainly to lower greenschist facies, during the Rangitata Orogeny (200-100 Ma). Historically this region has produced 240 tonnes of gold, 4% (10 t.) of which was from the mining of Cretaceous gold- quartz mineralised vein systems. Auriferous vein systems in the Otago Schist are mainly hosted within NW trending normal fault-fracture arrays, however NW trending reverse fault-hosted vein systems also occur. We propose that the Late Cretaceous-mid Tertiary Otago Schist structure represents a regional anticlinorium containing flexural folds of at least two wavelengths. The anticlinorium structure has been quantified by determining variations in angular discordance between schistosity and the Otago Peneplain, a Late Cretaceous-mid Tertiary erosion surface covering most of the Otago district. A structural model for the evolution of the post-collisional anticlinorium requires the cooling surficial zone (carapace) of a retrograding metamorphic belt to behave as an elastic lid. Erosion of topographic load on the carapace drove isostatic uplift, which was greatest in the tectonically thickened core of the orogen. In this way differential uplift produced flexural deformation in the elastic carapace, expressed as a large scale arching of the orogenic belt. Flexure created tangential longitudinal strains in the outer-arc, leading to extension and the formation of mineralised normal faults. These structures are separated by a neutral surface from shortening and associated mineralised reverse faults in the inner-arc. Our structural model predicts that the distribution of auriferous lodes should be localised about zones of maximum flexural curvature, where the tangential longitudinal strains are highest. As a result, NW-SE hinge regions separating schistosity dip domains in the Otago gold province may have new found significance as potential exploration targets.

Jan 1, 1995

By Aspinall T. O, Bell L. C

Increased awareness and stricter enforcement of regulatory requirements for adequate rehabilitation of surface mining sites has made environmental planning an essential part of strip mine planning. Rehabilitation is site specific and should be based on data which relate to that site. Cost-effective spoil pile design to minimise erosion is an important part of rehabilitation. Spoil pile design is an integral part of strip mine design. QCT Resources Limited has provided a postgraduate scholarship toward research in this area. The controlling factors of spoil pile design are post-mining land use, drainage requirements and degree and rate of erosion. The extent to which mine design is controlled by these factors is determined by regulatory requirements. To plan acceptable rehabilitation programs, erosion processes must be accurately modelled, and a range of erosion prediction models are available. Useful prediction models can be placed in two categories with the first category containing soil loss prediction models which can be used to predict the amount of soil lost from an area over a short or long term basis. Models in this category include the Universal Soil Loss Equation (USLE), Water Erosion Prediction Project (WEPP), Griffith University Erosion and Sedimentation System (GUESS) and Chemical, Runoff and Erosion from Agricultural Management Systems (CREAMS). The second category contains topographic evolution models which give an indication of the long term morphological development of a formed surface subjected to erosion processes. Models in this category include "Topog", Willgoose's Physically Based Catchment Evolution Model and Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS). The USLE has been used in the agricultural field for soil loss prediction. To apply the equation to mine sites in Central Queensland, it is necessary to understand the factors affecting erosion at the sites. This understanding should allow the variables of the equation to be quantified. The rainfall factor applied in the USLE is independent of engineering design or soil management techniques. The factor of spoil erodibility is dependent on the material's physical and chemical properties and can vary from site to site. In the equation, the topographic factor, cover and management factor and conservation practices factor can be varied by design to reduce erosion on rehabilitated areas.

Jan 1, 1991

By A E. Annels, M NoppT

Ore Reserves are key mining company assets and their reliable estimation is crucial for both feasibility studies and the day to day operation of a mine. The reserve is based on the Mineral Resource after the application of certain technical and economic parameters. Engineering aspects of reserve estimation can be accurately determined to ¦10 per cent, however the majority of project risk will revolve around the resource. A final Ore Reserve generally contains a set of figures quoted without reference to its potential errors. Rarely are overall confidence limits quoted and, if they are, they often do not take into account many of the factors that cause uncertainty in the grade and tonnage estimates. There is thus an unquantifiable risk, which the operator should be aware of. This paper presents a review of the possible sources of error that might occur during the various phases of an exploration and estimation programme which are carried through into the Ore Reserve and hence mine design.

Jan 1, 2002

The basic purpose of blast design is to produce rock in a size range which is within the requirements of the materials handling system. Once this is achieved, one would like to find the fragmentation which minimises total production costs. The former objective requires that fragmentation be assessed by some means, possibly as simple as counting the number of oversize rocks. To determine the 'optimum' fragmentation, however, accurate knowledge of the complete fragmentation distribution is required. The use of muckpile surface images to determine blast fragmentation is the only feasible technique when one does not want to disturb the production cycle; however, a number of problems exist with the use of images amongst which are determining size from a two-dimensional particle shape, estimating the fines which are missing due to image resolution, the size of a 'representative' sample, errors due to the distortion of particle images, etc This paper briefly describes methods of determining rock size from images and expands on the various errors which exist in assessing fragmentation by photographs. Methods to minimise and account for the errors are given, when possible.

Jan 1, 1976

A thousand writers have harped upon the wondrous nature of the inventive faculty. They realise that man is a creator, and that capital and labour alike are, and will always be impotent without machinery and processes that is invention. What Bacon has said is echoed by them all, "the introduction of new inventions seemeth to be the very chiefest of human actions. The benefit of new inventions may extend to all mankind-they make all men happy without injury to 'any' they are new creations and imitations of God's own works." My remarks will occupy another field I will refer to some of those features of the Patent Laws of different countries, which prevent the use of new inventions, oppress the development or inventive' genius, and diminish human happiness and progress' Wherever Patent Laws are framed and administered upon wrong principles, these results are inevitably found. A concise, complete, common-sense comparison of the chief Patent Laws of the world cannot easily be found but to avoid seeing scrappy, misleading references to Patent Law in the press particularly the English-would be equally difficult. Writers who are considered authorities so frequently make minor issues prominent and so uniformly fail to give weight to fundamental principles that the effect on the public is to mislead.

Escondida is a state-of-the-art copper mining operation. It is the major copper project of the 1990s and is the largest new investment in the industry - a US$823 million project. It accounts for about six per cent of Chile's total exports, making Escondida the largest private exporting company in Chile.

Jan 1, 1992

By P Crorkan

Within the framework in which future exploitations for Codelco-Chile Divisi=n El Teniente are situated, regarding the deepening of its reserves and the geotechnical problems that affect their recovery, it becomes strategic to evolve with new variants, which make deep mining possible. Codelco ChileÆs Divisi=n El Teniente is progressing within its long-term planning the exploitation of a sector called Esmeralda, which includes its removal through the gravitational caving method (panel caving). It is planned to use pre-caving, which basically consists of developing and undermining the undercut level, without having developed the infrastructure of the production and transport levels. This is carried out in order to achieve a better redistribution of the stresses, thus obtaining higher quality in the infrastructure development of these levels as well as less risk. The extraction reserves for this area, estimated through the opportunity cost selection criteria, were determined at 348 million tons with an average grade of 1.014 per cent Cu. The project carried out geological and geotechnical studies in order to prevent the geomechanical risks of the sector to be exploited, which is a site conformed totally by primary ore. Lithologically, it occurs mainly in Andesite, located at the western limit by Brecha Braden Pipe. There are also varieties of porphyries and hydrothermal breaches of anhydrite. The Esmeralda Mine production program will increase from 4000 tpd (average) in 1998 to its 45 000 tpd rate of production estimated for the year 2005. The approved investment for the period 1995 to 1999 is $US 150 million, out of a total $US 213 million for the project. At feasibility study level and before the project, it showed a Net Present Value of $US 342 million, an Internal Rate of Return of 37 per cent and an IVAN indicator of 2.3 for a ten per cent discount rate and a copper price of 100 US cents/lb.

Jan 1, 2000

The grades of alluvial ore deposits are low compared with grades of hard rock mining. This factor, combined with other parameters of irregular distribution of particles, bedrock irregularities, size of particles, nugget effect, ore characteristics, and wet horizons, combine to place alluvial deposits among the most difficult to evaluate, and on which to establish an ore reserve with a high degree of confidence. With increased geological input, correct selection and implementation of sampling method, due regard to sample representativity and process design, these confidence levels can be achieved.

Jan 1, 1987

The paper presents a brief history of endeavours to start a mining education programme which began in the days when Papua New Guinea's first large mine, at Panguna (Bougainville), was coming into production. The status of the Public Investment Programme in Mining Engineering and the facilities being created for the education and training of Papua New Guinean citizens in mining and mineral processing are also described. Future expansion plans are also detailed including those for the commencement of petroleum engineering and geological engineering which would include courses in mining geology, exploration geology, engineering geology and petroleum geology. The paper also looks at the manpower training requirements in the lower levels of mining industry such as pit foreman, blasting foreman and other similar positions. It stresses the need to start mining technical training programs at pre- employment level and at certificate level in a technical college, possibly Lae Technical Colleqe.

Jan 1, 1991

Mount Isa Mines' Hilton Mine was brought into large-scale production in 1990/91 at a time of sharply falling metal prices. To ensure the operation's survival and eventual prosperity there was an urgent need to reduce operating costs and increase revenue. A target of a 40 per cent increase in productivity over five years was set. Strategies to obtain the required improvements were developed on the basis of greater involvement and increased contribution from the workforce, major changes to the mining methods and the development and application of new technology. This paper describes the organisational, operational and technological changes that have been implemented at Hilton and presents the results achieved to-date.

Jan 1, 1993

By W Donovan

Concern exists about the potential release of metals from the proposed mining operation at Martha Hill to the Ohinemuri River. Speculation on possible impacts is fuelled by the dearth of published data on existing metal levels not only for this river system but for streams throughout the Coromandel. At first sight this lack of data is surprising given the apparent interest in this subject and the fact that future mining activity in this region has been a possibility since at least 1979. That such a situation has arisen is not altogether unexpected given the difficulties faced by various organisations, including the mining industry, in determining metal levels which are generally acknowledged to be low. This paper presents data for a number of stations in the vicinity of the proposed operation; it explains the analytical procedures which were adopted and the rationale for them and relates the information which has been obtained to water quality criteria.

Jan 1, 1986

With the introduction of the Health and Safety in Employment (HSE) Act 1992 and the subsequent repeal of regulations pertaining to mining, there has been an upheaval of the management of health and safety in mines.  More than ever, employers know that they must ensure that their workers are competent to carry out their assigned tasks.

Jan 1, 1997

By R Shrimali, P Rajmeny, L Shekhawat, A Joshi

Rampura Agucha open pit mine has successfully been excavated to a depth of 320 m, incorporating multistage working. The key to success is the implementation of presplitting as control blast measures at every stage of mining, including intermediate cut backs, in addition to the final wall. The major challenges encountered in establishing presplitting in the hang wall as compared to the footwall of the mine are:reversely dipping foliation, ie dipping into the hang wall itselfstriking obliquely at an angle of 20–30° with regards to the general strike of the pit wallthe presence of numerous geological planes of weaknesses like major faults, slips, etc.Control blast parameters like hole inclination, spacing and stand-off with buffer row were chosen initially from the literature survey and were subsequently fine-tuned by field trials to the mine geo-mining conditions of the hang wall. Electronic initiation used for trim blasts along with double presplitting in fault-affected zones helped in getting better presplit performance and resultant stability of the hang wall.CITATION:Rajmeny, P, Shrimali, R, Shekhawat, L and Joshi, A, 2015. Establishing the design parameters of a control blast for long-term stability of the hang wall at Rampura Agucha Mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 437–446 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Beardsmore G. R

Geothermal gradients in the Gippsland Basin commonly exceed 35¦ C/km. Consequently models of thermal maturation may indicate exploration targets with an anomalous age/depth distribution. However regional geothermal models are constrained primarily by observations of surface heat flow. High geothermal gradients may simply reflect the presence of low conductivity coal beds within the basin. Heat flow data are not readily available for the Gippsland Basin. Normally special purpose drill holes are required to provide direct determinations of surface heat flow. These provide core samples for thermal conductivity and allow measurements of a stable geothermal gradient at least one year after drilling. Different indirect procedures are now required to provide estimates for the Gippsland Basin. Bottom hole temperatures can be used with suitable corrections to provide an indication of the regional geothermal gradient. However the corresponding thermal conductivities are more difficult to determine. Geophysical logs can be used to detect the major lithologies but detailed statistical analysis is required for numerical estimates. Complex mixing models are now suggested for geothermal surveys linking physical properties to variations in the mineralogy of each well. Allowing for low conductivity coal measures the data in the Gippsland Basin suggest values for heat flow consistent with regional trends in Australia. Interpretation is complicated by overprinting of transient thermal events with different time scales. Apart from the tectonics of basin evolution geothermal signatures may be complicated by regional ground water migration, the 'hot spot' trace associated with southward younging of Cainozoic volcanism, diagenesis, and basin refraction.

Jan 1, 1992