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By Denholm W. T, Rankin W. J

The reduction of zinc from lead blast furnace slags using hydrogen was studied at 1300¦C as part of a laboratory investigation of zinc fuming. To perform the experiments, 300 g "spent slag" was melted in a crucible. Hydrogen was then injected into the slag through a lance and fresh blast furnace slag was added regularly in small quantities over a period of 40 minutes. Zinc added in the fresh slag was reduced and the zinc level of the bulk slag attained a steady state value of between 1 and 9% after about 10 minutes, depending on the gas injection rate. Because of the high reactivity of hydrogen, bulk supply of hydrogen to the slag was the rate limiting step at the flow rates used and it is believed that the gas-slag reactions in the system were at equilibrium. A partially/stabilized zirconia cell with a Ni/NiO reference electrode was immersed in the slags during the experiments and the steady/state oxygen potentials of the slags were measured. By using the experimental oxygen potential values and calculated values of the steady state concentrations of zinc in the offgas, the activity of ZnO in the slags was calculated from the Gibbs's free energy change for the reaction:

Jan 1, 1989

By N Harries

The management of risks associated with slope instability is an essential process in the safe and economic operation of open cut mines. The æslope stability radarÆ (SSR) has been developed to better manage those risks. The SSR can remotely scan a rock slope to continuously measure any movement of the face. The system can detect and alert users of wall movements with submillimetre precision. The high level of movement precision and broad area coverage of the rock face can allow for a better understanding of the geomechanics of slope deformation, including magnitude of potential failures and additional warning time of impending instability. Additionally, radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, 24 hours a day. SSR systems have been deployed in many mines in Australia, Indonesia, Africa, Chile and the United States. Greater than 100 rock falls and waste dump failures (from several tonnes to millions of tonnes) have been monitored, and on every occasion precursor æwarningÆ movements were recorded by the SSR. This technology enables a radical change in the management of risks in open cut mining. This paper presents recent case studies of how the SSR technology has provided safety and productivity benefits to large open cut metalliferous mines.

Jan 1, 2007

By Unver B

Longwall advance mining is still the predaninant system of coal extraction in the U.K., contribiiting to sane 70 % of underground coal production. Gate roadways providing access to a longwall advancing coal face are maintained adjacent to a rib pillar under high strata abutment pressures and the caving rock mass. It is very difficult to realistically model such access roadways using mathematical or numerical techniques and hence, predict roadway closure. For the past 15 years, a research group in Nottingham University has been engaged in the study of longwall gate roadway stability using observation methods. Gate roadway deformations have been measured in 224 gate roadways and a comprehensive data base has been established. The paper describes the statistical analysis of this database and presents sane. predictive equations which will enable a forecast of the gate roadway closure to he made. Further field work to validate these equations. is described together with an error analysis. The results are very promising and indicate that it is possible to predict gate roadway closure in the U.K. within practical limits of Accuracy.

Jan 1, 1986

By Z Chang, S A. Mrozek, S Windle

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. It is important to understand skarn-porphyry transitions in order to use exposed skarns to look for associated and potentially larger porphyries. For such purposes, a good start is to understand the transition between porphyry and skarn in known deposits. In this contribution, we report the transition at Antamina, Peru, where skarns occur in and around a Miocene complex comprised of more than seven porphyritic intrusions. There are three types of skarn-porphyry relationships. The earliest intrusive phase, P1A, contains both endoskarn and porphyry-style quartz veins with secondary biotite halos. The porphyry quartz veins and endoskarns formed at the same time. Locally, the intrusion contains only endoskarn without porphyry quartz veins and is surrounded by exoskarns in carbonate wall rocks. In the third scenario, later porphyry (P2) intruding into P1A porphyry and skarns related to P1A contains abundant granular quartz veins and secondary biotite alteration but does not have significant endoskarn. The granular quartz veins also extend into earlier P1A skarns. The scarcity of endoskarn associated with P2 is related to the supply of Ca. The earliest P1A intrusion intruded into carbonates that supplied abundant Ca, therefore both endoskarns and exoskarns formed. In contrast, where the wall rocks of the later P2 intrusion are P1A or skarn related to P1A, there was little free Ca, therefore only porphyry-style quartz veins formed.CITATION:Chang, Z, Mrozek, S A, Meinert, L D and Windle, S, 2015. Skarn-porphyry transition – an example from the Antamina skarn, Peru, in Proceedings PACRIM 2015 Congress, pp 409–414 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The St George orebodies are situated within the tectonically disrupted eastern limb of the Boogardie Syncline.Highly disturbed rafts of banded chert formations occur within a sequence of felsic volcanic tuffs. The chert forms the hostrock for the gold mineralization.The gold distribution within the irregular and narrow banded chert formations is erratic and patchy. The average gold content of the two orebodies is between 3 - 4 g/t Au.Economic mining of these relative small, irregular and low grade St. George orebodies can be carried out by using a highly selective mining method.The highly selective mining method uses an excavator as the principle mining tool. Blasting, breaking and loading of the rocks is done in a different way than by using a front-end loader as with the conventional mining method. Simple, and therefore cheaper, blasting breaks the rocks and lifts them up without major displacements.

Jan 1, 1984

By Still RF

Sintering of lead and zinc concentrates is practised by Sulphide Corporation Pty. Limited to provide both desuiphurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulphur dioxide gas for sulphuric acid manufacture. From November, 1969 a 20 percent increase in production rate has been obtained through improvements in operating technique. A gradual increase in bed permeability was achieved by modifications to the feed mix conditioning equipment and by improving moisture control. However advantage could not be taken of the higher permeability to increase sulphur elimination because the hardness of the lump sinter decreased. Higher throughput, better quality sinter and more stable sintering conditions were however made possible by simultaneously: 1. reducing segregation and compaction in the sinter bed, by narrowing the discharge opening of the main layer feed hopper, 2. reducing the sizing of sinter returns to give a closer size spectrum of particles in the feed mix, and 3. increasing the sulphide sulphur content of the feed mix to give higher bed Temperatures.

Jan 1, 1972

By A J. Tucker, L Bottomley

The principle objective of development mining is to create thoroughfares that can be accessed by personnel and machinery for the entire life of an underground mine. The drill and blast process, being the primary method used when creating these thoroughfares, needs to be able to adequately fracture the rock to be removed whilst at the same time minimising any damage that may be sustained to the rock surface that remains. This process of damage prevention is known by a variety of different names including smooth blasting, sculpture blasting, contour blasting and controlled blasting. Whilst the terms are different, the objective is the same and that is to reduce and better distribute the explosive charges to minimise stressing and fracturing of the rock beyond the neat excavation line. The process in this report will be referred to as perimeter control blasting. This paper will discuss the benefits of using perimeter control blasting in a development mining operation and the theories that govern how these blasting techniques work. The methods that are used to implement perimeter control blasting will also be addressed, paying particular attention to how these blasting techniques have evolved, spawning new and improved perimeter control products. Finally some attention will be given to the process of optimising perimeter control blasting in any underground mining operation.

Jan 1, 2005

With mining development on hold and other underground works in a slowdown, the development of nuclear wa te repositories takes centre tage on the American rock engineering scene. Three repositorie for commercial spent fuel-in salt, tuff, and basalt-are in the phase of site characterisation and conceptual design, and one pilot project for defense high-level wa te in salt is under construction. A repository design for crystal line rock has recently been postponed.Because of strict quality assurance requirements throughout design and construction, and because of the need to predict and ascertain in advance the satisfactory performance of the underground openings, much intellectual energy has been expended to analyse underground openings in the unusual circumstances of the repository environment. In the long term, these efforts will lead to an improved understanding of rock behaviour and improved methods of underground analysis and design. For the shorter term, a formalised ground control plan was developed, the principles of which may be applied to other types of projects.This paper summarises the status of underground design and construction for nuclear waste repositories and presents some details of the ground control plan and its individual elements.

Jan 1, 1988

By Singh RN

The Bulli Coal Seam, located in the Illawarra Coalfield of New South Wales, has a long and varied history of sudden outbursts. From available information this problem has resulted in twelve fatalities over the last one hundred and one years, with over five hundred separate outburst incidents being identified. These incidents have varied in severity and intensity from the discharge of 1 to 2 tonne of coal, with a slight increase in gas emission, to the discharge of 200 to 400 tonne of coal with some 6,000 m3 of gas being liberated and large items of mining equipment being pushed 1 to 2 metres down the roadway.Geological features associated with these outbursts can be mapped on a regional and mine by mine basis, to provide some indication or warning. Similarly changes in gas content and gas composition can also be determined on a regional and mine by mine basis. However sudden geological changes (such as a 6.5 metre seam displacement within 15 metres) variations in gas content (such as 6 m3/tonne to 15 m3/tonne) and changes in gas composition (from 95% CH4 to 90% CO2) all within one mine does make the prediction or forecasting of outburst incidents exceedingly difficult.

Jan 1, 1998

Iron ore in the Pilbara Region of Western Australia varies in composition giving iron ore a range of densities. An accurate density figure of the material leads to accurate calculations of production throughput. Density studies of two separate iron ore mines were conducted in the Pilbara. Procedures and results are reported here.The Pilbara Region of Western Australia has a number of iron ore operations. Two mines have conducted density studies of their materials. The purpose for the studies was to determine an accurate in situ bulk density that could be applied to volume and tonnage calculations of the operation. It was identified that density was one culprit causing calculation variations. Density is an important figure used to estimate ore reserves, equipment requirements, production rates and indirectly costs and sales revenue. One study was conducted at Rio TintoÆs Robe River Mine based near the town of Pannawonica. Its Mesa J orebody is currently being mined and is a low-grade deposit of goethite and hematite (Burnham, 2003). A separate study was conducted at BHP BillitonÆs Yarrie Mine situated north of Newman and east of Pardoo. Its orebody consists of high grade formed by a supergene enrichment of cherty material and a burial metamorphism to produce hematite (Richardson, 2002). The method used to determine density was by large-scale samples using the pre-mining in situ volume of the material and the weight in tonnes after mining.

Jan 1, 2003

By A Kuras

Segmental tunnel linings are becoming more common in Australia. One current project employing a segmental lining is the City West Cable Tunnel (CWCT) in Sydney. The project has been commissioned by Energy Australia and is currently being constructed by Thiess Pty Ltd. The project includes 1.6 km of tunnel boring machine (TBM) driven, segmentally lined tunnel. The majority of the CWCT will be excavated through Hawkesbury Sandstone. The tunnel is required to carry a 132 kV electrical circuit under SydneyÆs central business district (CBD), between Haymarket and Energy AustraliaÆs City North Substation on Sussex Street. The segmental lining has been designed as a 3.2 m internal diameter, 200 mm thick universal ring with six trapezoidal segments. The design and detailing of this segmental lining presents some noteworthy challenges, including exposure to saline groundwater, and the exclusive use of steel fibres for flexural and tensile concrete reinforcement. This paper describes some of the key elements of the segmental lining design. These include:the case for choosing segmental linings over other forms of tunnel construction;the major design checks required of a segmental lining including ground loading, hydrostatic loading, joint bearing, joint rotation, ram loading and the early strength lifting case;the benefits of using steel fibres over conventional steel reinforcement;the design approach used for steel fibre reinforced concrete;the application of 3D computer modelling in the design;the provision for components including connector dowels and gaskets;the design for passive fire resistance; andthe design for durability of steel fibre reinforced concrete in a saline environment. Segmental lining design requires the application of specialist design approaches. Input is required by the construction team, as the methods of demoulding, handling, transportation and installation impact on the lining design. As the segmental lining is functioning as immediate ground support and also a permanent lining, high standards of manufacture and construction quality control are required to ensure that the 100-year design life is met. The requirement for a watertight tunnel means that detailing and installation of the EPDM gaskets is of importance.

Jan 1, 2008

By A Logan, B Cuthbert

Brown and Chitombo (2007) indicated that during the last two decades, the international mining industry has been using mainly mass mining methods to extract safely and economically some of the important commodities such as copper, diamonds, gold, iron and nickel. Mass mining may be implemented either on the surface through large open pits or underground using mining methods such as sublevel, block and panel caving. Developments in the last ten years have demonstrated that caving methods can be applied successfully in strong orebodies at greater depths and in increasingly challenging geotechnical environments for which more traditional mining methods would be unsuitable, unsafe and/or uneconomic. These underground mass mining challenges require æfront endÆ investigation and analysis, robust engineering design and disciplined implementation and operation. Newcrest Mining Limited has focused its efforts on the development of gold/copper projects of substantial scale and margin. To help achieve this, the company is applying and further developing mass mining methods. These include large-scale open pits (OP) and underground mining methods such as sublevel (SLC), block (BC) and panel caving (PC). Block and panel caving now offer economies of scale opportunities for Newcrest to achieve high production rates at lower production costs; thus enabling the exploitation of mineral endowments at higher margins. This paper discusses the practical aspects of caving technologies that Newcrest continues to develop through its expertise at Telfer and Ridgeway SLC operations, Ridgeway Deeps BC and Cadia East PC projects.

Jan 1, 2008

The implementation of a process information management system (PIMS) is to provide a single online, real-time information system. This system provides a unique and completely open view for everyone, based on the key business drivers. It is structured around the three key concepts: process, maintenance and stocks. It combines numerous applications and provides accessibility to common tools and reports, through a web-based user interface, for every one from the floor operator to the General Manager. This æunique and commonÆ view displays raw, online process information that provides a quick health check of the operation at a glance, highlighting areas that require further investigation. The system is based on a hierarchical system of views, from the overview of the whole plant flow sheet to the more detailed operational shop view. It provides a synthetic view between continuous and batch operations, enabling the tracking of each batch produced. The batch view displays the critical batch components, and a comparison with each component of an ideal batch. This enables detailed analysis of each batch to identify areas of improvement. The information system will consist of an online reconciliation of stocks and flow data. This enables focus on the recovery of each process unit on a regular basis. This paper discusses the design strategy for the Process Information Management System, to ensure a unique and open view on the key business drivers is achieved and implemented successfully.

Jan 1, 2005

The difference between a hypothetical and a theoretical approach is considered and the advantages in using a hypothesis is discussed. Virgin horizontal stresses play an important role in stabilising strata which bridge across an excavation, and reduces the tensile stresses which develop in a beam subjected to bending. Simple formulae are deduced for the bridging of a thick massive stratum under such conditions. At shallow depths, tensile failure on the upper side of the beam is the most likely cause of fracture, but below a certain depth this gives place to compressive failure on the underside, with the possible incidence of rock bumps. The presence of strong massive beds delay the onset of subsidence and may restrict the width of the subsidence trough. If the material involved in the caving is strong, this will reduce the final subsidence, especially at shallow depths. The British regulations for the control of aquifers and their dependence on the strain developed at the seabed are discussed. As an alternative, the concept of a disturbance factor is introduced to permit the consider- ation of aquifers at depth, leading to an explanation of the make of water on the first faces to be mined in the Selby Coalfield. 'Elie paper closes with a brief consideration of the different roles played by longwall face supports in the control of readily cavable strata, and the control of strong beds which hold up in the waste.

Jan 1, 1986

Geostatistical conditional simulation is a method to assess variability and risk in mineral deposits and the tool has wide potential applications in the iron ore industry. Correct reproduction of multivariate relationships is important in iron ore simulation, especially between Fe and impurities such as Al2O3, SiO2 and P. The turning bands simulation method, using a full model of coregionalisation for multiple attributes, is the main multivariate conditional simulation algorithm used in the Western Australian iron ore industry. This paper discusses the results of a more recent approach using minimum/maximum autocorrelation factors (MAF) to transform and decorrelate the multivariate data prior to independent sequential Gaussian simulation (SGS). MAF-SGS results are compared to those of the turning bands approach in the Yandicoogina channel iron ore deposit (CID), and both methods performed well in simulating Fe, SiO2, Al2O3 and P distributions. Extensive checking of simulations showed that both approaches could reproduce multivariate statistics and spatial continuity of the original conditioning data. Both approaches reproduced the histograms and variography of input sample composites. While the MAF-SGS approach requires additional transformations when compared with the single normal scores transformation required for the turning bands method, MAF requires only that the direct semivariograms be modelled. In contrast, using turning bands with multiple attributes requires modelling a full linear model of coregionalisation, which can be difficult to model because of the need to ensure the model is positive semi-definite. Turning bands may be preferred if there are a modest number of correlated variables allowing construction of a linear model of coregionalisation that adequately models the multivariate behaviour. MAF-SGS is preferable for larger numbers of correlated variables. Both MAF-SGS and turning bands methods performed well in conditional simulation of correlated variables at Yandicoogina.

Jan 1, 2007

In discussing the Asia-Pacific region weare talking about a region which has more than 60% of the world's population, a regional economy which will in 10 years be larger than the European Economic Community, and a group of countries with some of the highest electricity generation growth rates in the world. It is economically the most dynamic region in the world.

Jan 1, 1990

YOUR Excellency, Fellow Members of the Australasian Institute Of Mining Engineers and Gentlemen:- Nearly a decade has passed, since our Institute first met in New Zealand. May I, at the very outset of this second gathering, congratulate the Institute on the great progress that has been made in the interval. At the first meeting in New Zealand in the year 1903, I understand that less than 20 persons were present, and now in the large concourse before me I believe there are not fewer than 140 persons, while if every member of the Institute to-day where here there would be over 500 which is a great change from a membership of only 250 in 1903. I feel deeply appreciative of the honour you have conferred upon me by electing me your President for the year 1911. In return for the compliment, may I ask you to believe that I shall do everything in my power to further the interests of the Institute throughout the coming year.It is a great regret to me to realise that soon my work in New Zealand will be over. However, I trust that the new...

Jan 1, 1911

By E P. Donohue

Changes to water industry practice are required as a consequence of the Council of Australian Governments water reform agenda which binds all states and territories to a range of measures intended to drive new efficiency, sustainability, higher value use and proper provision for environmental needs. Queensland is implementing its reforms program through its water resource planning process, a legislatively underpinned program that provides for a new level of social, economic and environmental security. A water resource plan for the Fitzroy Basin has been finalised and its implementation plan, which details infrastructure operational arrangements for the basin, is due to be released later this year. The mining industry is a major contributor to the economy of the Basin, and although a comparatively minor water consumer, is now aligning its water use practices with the stateÆs maturing integrated resource management paradigm. This new culture presents both challenges and opportunities. Water reform in the Fitzroy basin is well advanced. The processes and institutional arrangements that have been developed are of significant importance to the aspirations of current and future minerals development. This paper outlines the current status of those reforms and the likely institutional framework for the near future. The paper also discusses how the reforms impact on the availability, access and security of water available to mining interests.

Jan 1, 2003

By Klenowski

Rational design of layouts for longwall operations is greatly facilitated by use of an accurate and economical method for predicting stresses and displacements. The displacement discontinuity method (a form of boundary element method) is based on replacing actual excavation geometries by thin slits of the same plan area. This approach allows three-dimensional stress- analysis at a fraction of the cost of alternative methods. The analyses can be readily performed on economical microcomputers, putting the analysis capability within the reach of mine-site personnel. This paper describes investigations associated with the German Creek Central Colliery, the first longwall operation in Queensland's Bowen Basin. The material properties used in the model, in particular the rock mass and goaf properties, have been 'tuned' to fit stress measurements obtained during extraction of the first and second longwall panels at the mine. The study shows that model predictions based on suitably scaled anisotropic rock strata properties are in good agreement with the stress measurements made to date. This model predicts average chain pillar loads significantly higher than predicted by models based on United Kingdom conditions. A working chain pillar design method is proposed using average pillar loads predicted by the numerical model and ultimate strength characteristics given by Bieniawski's formula.

Jan 1, 1988

Copper entering a lead ,smelter in concentrate or from other sources is recoVered as matte and speiss which contain appreciable quantities of lead. The matte and speiss are usually sold to copper smelters to recover the copper content and also any gold and silver in these products, but the value of the lead is largely lost. Some copper plants pay for portion of the lead content, but regarded as a means of recovering lead it is more costly and less efficient than if the lead were recovered at the lead smelter.Because of the value of this lead loss, the metallurgy of copper recovery has assumed greater importance in recent years owing to the rise on the price of lead.Two processes are in use today to produce matte and speiss, namely the iron matte process and the soda matte process developed by the American Smelting and Refining Co. 1 in D.S.A. The latter process is characterised by a higher copper to lead ratio than the older iron matting process.The following analyses are typical of matte and speiss produced at Broken Hill Associated Smelters, by both processes, although the soda matte process is still in a developmental stage and experience indicates that matte and speiss of lower lead tenor can be produced under favourable conditions.

Jan 1, 1951