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By J Karlovšek

Civil engineering infrastructures are often subjected to different types of natural and mechanical activities. These influences may result in serviceability or even in stability of structures due to material deformations, increased water content within the materials used or the formation of internal or adjacent cavities that may threaten the infrastructure. Construction practices can lead to development of such defects in the form of cavities. In civil engineering it is crucial to detect these variations in material properties and to detect the presence of defects. However, as they are often hidden from view, these attributes may be difficult or impossible to target with traditional testing methods. For these reasons rapid geophysical methods, such as ground penetrating radar (GPR), are increasingly being used. At the University of Queensland (UQ) GPR is used for detection of voids and cavities which have been caused by an over excavation of the earth pressure balance machine (EPB) operating in a closed mode.A variety of numerical simulations using the finite-difference time-domain (FDTD) methods and preliminary experiments have been carried out in order to specify information about the nature, type, size, location and other characteristics of targets to be detected by GPR. In doing this the difficulty of interpreting GPR data, which is mainly due to the complexity of the factors involved in multiple possible solutions of the observed features, can be overcome.

Mar 8, 2011

By Nikaido M, Kanda Y

A rotary type separator has been developed which separates particles on the basis of their shape. This separator was applied to a particle size range of about 50 - 120 ¦m, and to our present knowledge may be the smallest size range ever to be separated. A theory of the separation is given based on the difference of an adhesive force of the particles: the adhesive force between spherical particles and plate is more powerful than that of irregular shaped particles for the same particle size. These facts have been ascertained by the measurement of an adhesive force by a centrifugal method. US and Japanese patents have been obtained on this separator, which consists of a borosilicate glass cylinder of 150 mm outside diameter, 120 mm in width, and an AC electromagnet. The samples used in this study were mixtures of spherical glass particles and non-spherical shaped glass particles. The results are summarised as follows. In the case of mixtures of spherical particles and irregular shaped particles in the weight ratio of 1:1, the spherical content of the spherical product became 70 per cent - 75 per cent, and in the case of 3:1, the content became 87 per cent - 90 per cent, as the result of one separating operation. However, for a mixture of somewhat rounded particles and irregular shaped particles of weight ratio 1:1, the rounded content varied between 58 per cent - 73 per cent. The feed rate of the particles mixtures was about 0.3 g/min. Newton's Efficiency was 20 per cent - 60 per cent. The separator may find application in shape separation of ceramic powder, metal powder or industrial diamond powder.

Jan 1, 1993

By Mine F. J, Woods P. H

The Top End of the Northern Territory lies in the monsoonal zone and receives rain during the November-April period. Initially, at the start of the wet season, rain storms are localised, but, following the descent of the monsoonal trough from below the equator, widespread rain occurs. Overflow incidents at mine sites tend to arise midway through the annual wet season when excess water accumulated in ponds begins to discharge to the external environment. Remote-access monitoring may be undertaken at mine sites using equipment to continuously measure water quality parameters with storage of the information on a data logger. The data is then retrieved by visiting the site and transferring it to a portable computer or by remotely accessing the system using a telemetry system and transmission via telephone, VHF/UHF or satellite. Such systems are readily available and vary in cost depending on the sophistication of the data transfer system. Available sensors for continuous monitoring include those for conductivity, temperature, pH and other ion selective electrodes, eg nitrate, and water level. Of these variables, conductivity is most useful due to its inherent accuracy and stability of reading. Remote monitoring capability is able to provide: (i) more intensive monitoring of key issues; (ii) more timely information; (iii) correct perspective on the degree of environmental problem; and (iv) information from remote locations, which would be difficult to monitor by more conventional methods. Examples are given for applications of continuously logged measurement of conductivity of waters discharging to drains and in creeks at Pine Creek, Ranger, Nabarlek and Woodcutters mines in the Northern Territory. These applications demonstrate the timeliness of the continuous monitoring technique.

Jan 1, 1994

By Robertson K. S, Hunter T. C

AEG-Elotherm's electromagnetic dosing channel, or Eldomet, is a recent invention enabling the transport and metering of molten metals. The development of a reliable refract- ory lining, and the use of suitable construct- ion and operating techniques has led to the successful application of the Eldomet for casting copper anodes at Copper Refineries Pty. Ltd.

Jan 1, 1974

By Bucknell WR, Clarke DE

The paper provides a company's view of the relative merits of various valuation methods and outlines the basic approach it takes to the valuation of an exploration property. The negotiating process and methods of acquiring an interest in an exploration property is discussed The valuation methods discussed are: 1. Exploration Expenditure. 2. Real Estate. 3. Joint Venture Terms. 4. Rule of Thumb. 5. Net Present Value - Discounted Cash Flow. 6. Geoengineering.

Jan 1, 1994

By P A. Montoya

La Colosa is a world-class porphyry Au project located in Colombia, currently undergoing prefeasibility analysis. As part of collaboration between AngloGold Ashanti and the AMIRA P843A GeMIII Project, the application of emerging geometallurgical characterisation testing and modelling tools has been incorporated in early stages of project development. The aim of the geometallurgical study is to map inherent comminution variability across the La Colosa deposit providing information critical for mine/mill design and optimisation. In this study, site-based data incorporating multi-element assays, quantitative analyse X-ray difraction QXRD bulk mineralogy measurements, EQUOtip rebound hardness data, and routine geological logging information from 59 diamond drill holes has been integrated with a range of geometallurgically specific comminution test (ie GeMCi, A × b, BMWi). The work in this paper demonstrates the integration techniques used at La Colosa to link routine data acquisition methods with comminution test results through the development of proxy support models. The integration incorporates a range of statistical techniques including principal component analysis and regression modelling. By creating proxy models, comminution index estimates can be propagated into the geological database enabling comminution processing domains to be defined. These domains provide the first spatial representation of comminution performance and variability at La Colosa and can be compared against traditional geological domains. This study provides the foundation for ongoing comminution characterisation as the La Colosa project evolves through project cycles into an operational mine.

Sep 5, 2011

By P Malkin, S Thomas, P M. Stone, D Kostyuk

In open pit mining, it is common that the bottleneck to productivity and profit lies in the truck-shovel mining operation, especially as strip ratios and mining intensity have increased with resource depletion and advances in mining equipment capabilities. This paper outlines a study of truck-shovel productivity using a new proprietary discrete event simulation platform for truck-shovel operations called MineDES. The study will specifically address the issue of whether truck queuing at shovels should be considered productive or not, and how mining engineers can determine the optimal truck fleet size for specific operational configurations.The MineDES simulation platform will be described and illustrated, highlighting the features that make it an appropriate tool for conducting the experiments at the heart of this study. The study encompasses a set of experiments, consisting of a number of simple truck-shovel operational scenarios for a benchmark open pit mining operation, which are simulated using MineDES. Each experiment is designed to highlight different factors, which are most important in calculating the ideal truck fleet size and for understanding the marginal productive impact of each additional truck added to the fleet. The scenarios will principally address the issues of how different types and levels of unscheduled equipment downtime and process variation, combined with the traffic delays/congestion arising in more intense mining operations, will affect productivity. The results of the experiments are interpreted using a simple fit-for-purpose cost and revenue model in order to highlight the indicative cost of over- or under-trucked configurations.The study has found that the optimal fleet size that maximises productivity and value will, in the presence of even small process variation, lead to non-zero trucks queuing at shovels on average. As process variations and unscheduled downtime events increase in the truck-shovel system, the required fleet size to optimise productivity and value increases. MineDES provides a convenient platform for quantifying this for real operations.CITATION:Kostyuk, D, Thomas, S, Malkin, P and Stone, P M, 2014. Is truck queuing productive?, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 267–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By R Minnitt

Two methods of calibrating the parameters K and Alpha for use in Gy’s formula for the fundamental sampling error were investigated. Approximately 480 kg of broken ore from Harmony’s Target gold mine in South Africa was used to compile the replicate samples for two experiments. The duplicate series analysis (DSA) and segregation free analysis (SFA) methods differ in terms of their approach to recovering the sized materials required for the calibration procedure. In this experiment the DSA method split off six more-or-less equal masses of material from a 75 kg lot that was successively crushed to finer and finer fragment sizes. The sublots so formed were split into 32 samples and fire assayed for gold. The SFA method used approximately 250 kg of broken ore crushed to 95 per cent passing 2.50 cm, which was then passed through successively finer screens until a sublot of less than 0.0075 cm was obtained. Each of the 15 sublots obtained in this way were split using a riffle splitter into 32 samples that were fire assayed. A total of 672 fire assays were used in these experiments. The sampling parameters K and Alpha were used for the compilation of a nomogram and to calculate the gold liberation size of the ores. While there are no definitive results in terms of the actual gold grain sizes against which the calculated sizes can be compared, it appears that the DSA method produces more acceptable results.CITATION:Minnitt, R, 2014. A comparison of two methods for calculating the constants K and alpha in a broken ore, in Proceedings Sampling 2014 , pp 165–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By D J. Williams, S Islam

Fine-grained coal tailings slurry undergoes only limited settling and self-weight consolidation, and tends to remain slurry-like and unsuitable for conventional laboratory consolidation testing. In addition, constant rate of loading consolidation testing is more representative of the continuous disposal of tailings slurry into a tailings storage facility (TSF) than conventional step loading. The laboratory consolidation testing of coal tailings slurry under a constant rate of loading has been carried out in a purpose-built, large-scale, slurry consolidometer, instrumented with load cells and pore water pressure (PWP) transducers. In the slurry consolidometer, the rate of loading may be varied to represent the actual rate of rise of the tailings in the TSF. A slow rate of loading increases the test duration, while too fast a rate of loading may build up very high excess PWP, without achieving significant consolidation. For the particular fine-grained coal tailings slurry tested, the rate of loading in the slurry consolidometer is varied to access its effect on the development and dissipation of excess PWP. The resulting consolidation parameters are evaluated and explained using the recorded settlement and PWP data.CITATION:Islam, S and Williams, D J, 2018. Optimisation of constant rate of loading slurry consolidometer testing of fine-grained coal tailings, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 72–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By S E. Thornett, P L. Kitto, R S. Longley

"The Mbalam Iron Ore Project covers mineralisation in two areas of metamorphosed hematitic banded iron formation (itabirite) in the north-west Congo Craton; namely at Mbarga in south-east Cameroon and at Nabeba in north-west Republic of Congo. The site locations are shown in Figures 1 and 2.The Mbalam Project history is an example of a compressed, yet highly successful, exploration timetable. Due to the thick inaccessible equatorial forest location, the first access was by helicopter in February 2007 at the Mbarga Deposit. Drilling commenced four months later in June 2007. A maiden JORC Code compliant æhigh-grade hematiteÆ inferred mineral resource (190 Mt at 60 per cent Fe) was defined in May 2008, followed by a maiden æitabirite hematiteÆ inferred resource in July 2008 (1.2 Bt at 37 per cent Fe). Subsequently, road access to Nabeba was established in January 2010, with a maiden high-grade hematite inferred mineral resource (200 Mt at 63 per cent Fe) identified only five months later in June 2010. A maiden itabirite hematite inferred resource at Nabeba was announced in June 2012 (1.4 Bt at 34 per cent Fe). The success of the exploration programs has been due to two main factors: Establishment of high-quality camps and facilities at Mbarga and later at Nabeba in Republic of Congo. Exploration support included satellite links for site servers and communications, field logging computers, data acquisition software, an on-site sample preparation laboratory, portable hand-held X-ray fluorescence (XRF) and company-owned drill rigs from 2009. An experienced and dynamic technical support group based in Perth to provide database facilities, data evaluation, internal auditing and software support, resulting in expedited resource estimation and economic evaluation with state-of-the-art mining software. In June 2012, Sundance Resources Ltd announced the current mineral resources for the project of 775.4 Mt at 57.2 per cent Fe of high-grade hematite and 4.047 Bt at 36.3 per cent Fe of itabirite hematite. In December 2012, high-grade hematite ore reserves of 436.3 Mt at 62.6 per cent Fe were announced. These world-class resources and reserves have been delineated and evaluated in a very rapid time frame. This would be considered extraordinary in any environment, let alone in the remote equatorial forest of central Africa.CITATION:Longley, R S, Kitto, P L and Thornett, S E, 2013. Exploration history of the Mbalam Iron Ore Project, in Proceedings Iron Ore 2013 , pp 107-116 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

Mother Nature controls, technical professionals model and miners decide. Decisions to explore, mine and mill. Mine decisions, mine design, planning and scheduling are subject to the quality of models û geological models, geotechnical models, resource models, density models. The closer these models are to reality, the more accurate the predicted outcome. So why is it we delegate the modelling tasks to the most junior and least experienced people? If we insist on this, we need to support them û to provide them with æexperience acceleratorsÆ. Technical mentoring is the most effective way to provide the right information at the right time. When this information (read skills) is supplied at the right time we can inject experience into the quality of our modelling and into our decision- making processes. The objective of this paper is to share those behaviours and manners that foster relationships and create frameworks for skills and experience transfer. Central to this is an understanding of how adults learn, an understanding of the basic rules of mentoring etiquette, and the three keys to building meaningful mentoring relationships. An understanding of adult learning processes and styles provides a structure within which a mentor can understand the learnerÆs perspective. Understanding the world from the learnerÆs point is critical to selecting the right language to engage, teach and transfer skills. Basic rules of mentoring etiquette like timeliness, respect and trust need to be brought into the consciousness so they can be agreed on and monitored to prevent conflicts in cultural and generational norms between the mentor and the learner.Meaningful relationships hinge on the three behaviours: truly listening, rather than just hearing; understanding the technical issues within the WIIFM (whatÆs in it for me?) question; and facilitative behaviour. Stronger and more meaningful technical mentoring relationships within our industry will bridge the generational gap and ensure we can capture and capitalise on the wealth of grey hair experience and develop an informed group of young decision-makers.

Jan 1, 2006

By P C. J Blackney, I M. Glacken

Spotted Quoll is a massive sulfide nickel deposit located in the Forrestania greenstone belt in the Archaean Yilgarn block in Western Australia. Discovered in October 2007, mining has progressed from open pit to underground and currently uses longhole open stoping with paste fill as the primary stoping method. Immediately prior to 2019, the Mineral Resource estimate (MRE) was defined by a single grade domain of nickel greater than or equal to 0.8 per cent, irrespective of the host lithology, a legacy of the original ore wireframe being built using explicit methods. While a number of obvious structural offsets were honoured in this nickel grade domain, only one modelled fault was used to undertake domaining of arsenic. From 2019 onwards, implicit modelling in Leapfrog Geo™ was used to construct a mine-scale geological model, which triggered the definition of a high-grade core of massive/matrix nickel sulfides surrounded by a low-grade halo of stringer/disseminated nickel sulfides in the surrounding rock. As part of the evolution of the geological model and with the aid of Seequent Central™ to allow collaboration between site-based mine geologists, Perth-based resource geologists and Melbourne-based consultants, a detailed review of the structural mapping was carried out as additional information from underground development became available. This allowed numerous faults and shears to be identified – particularly in the lower half of the mine. These were used to define further structural domains and to refine the understanding of the nickel and arsenic grade distributions in the mineralised envelope. The increased definition to the domains provided by the geological model resulted in a significant improvement in the accuracy of the Mineral Resource estimate, as measured by reconciliation using voids of the mined stopes determined from the cavity monitoring survey (CMS).

Mar 22, 2022

By Y Akiti, J Moller, E Esper, R Rugolo, A Pains

"Morro do Ouro Mine is a high tonnage/low-grade mine located in Paracatu, Minas Gerais State, Brazil. The mines move around 55 Mt of ore per year at an average grade of 0.4 g/t. The auriferous mineralisation of Morro do Ouro is related to hydrothermal fluids rich in arsenic (As), gold (Au), lead (Pb) and zinc (Zn). These percolated along favourable structures contained within phyllites of Upper Proterozoic age and defined a mineralised megaboudin which outcropped with 4 km extension and up to 2 km in width. The litologies in the interior of this structure are typically more deformed, sericitised and sulfidised, and exhibit the development of quartz boudins in the centre of the more deformed zones where are found the higher Au grades and the coarser sulfide crystals. Gold is preferentially associated with arsenopyrite, mainly occurring in fractures or aggregations of crystals and is rarely in solid solution or refractory. Over 90 per cent of the gold contained in the sulfide ore is free or extractable by cyanidisation. The current mineral reserve is 17.9 Mt at 0.403 g/t published at the end of 2012.In order to get a good grade estimation that represents the orebody more accurately a solids methodology was used to distinguish the different orebodies. Before 2011 the orebodies were worked with two domains relating to the weathered mantle. The B1 ore, which is oxidised, is located at the top of mineralisation, and is used to feed Plant 1. Underneath B2 ore, which is fresh sulfide bearing, represents over 30 years of production in Plant 2.In order to improve the predictability of gold grade estimation in geological modelling and to get a better predicting behaviour of each domain on the deposit, studies were carried out in which it was possible to show a correlation between elements and the mineralisation. One strong correlation and spatial distribution between Au and As, As and sulfur (S), Au and Pb, Au and Zn were found.Based on geochemistry, mineral correlations, amount of sulfide, structural deformation, texture of sulfides and the daily experience of the mine, it was possible to create solids that individualised bodies with similar mineralogical and chemical characteristics using the parameters listed above.After 2011, a new modelling concept was proposed and built with 11 different domains, compared with the previous, and with two more parameters: recovery acid neutralised capacity (ANC).Each of these bodies have different behaviours in mineral processing, like flotation and metallurgy. For example, bodies with pyrrhotite bring problems in the flotation, bodies with high arsenic do not recover well, bodies with high As with coarse texture have good recovery, bodies with fine texture do not have good adherence in production.In the present state of knowledge, protocols are being developed for bench testing to predict the recovery of each geochemical domain aiming to include these in the geological model for the parameter recovery. It is intended to create a field throughput in the model of ounces per hour, from each block of each domain to better predict the production, using the parameter recovery, Au and Bond Work Index (BWI).CITATION:Esper, E, Rugolo, R, Moller, J, Akiti, Y and Pains, A, 2013. Morro do Ouro geological model with a metallurgical view, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 67-74 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By P Kittler

In the spectrum of mining-related disciplines, geometallurgy sits between resource geology and metallurgical engineering. Unlike its neighbours, it is a relatively young discipline and its concepts, procedures and techniques are still evolving. Relevant geometallurgical issues differ from one deposit to the next so there is no single template that can be used in all situations, meaning that geometallurgy programs are nearly always customised and tailored to the deposit and the situation.Over time, a number of key mistakes are seen to emerge regularly. The eventual impact of these mistakes can vary from suboptimal performance of mine and plant to complete failure of the operation. For instance, poor characterisation of ore lithologies and their spatial distribution can have negative impacts on processing plant throughput. However, when combined with failure to identify critical blending constraints it can result in a totally inoperable plant.A number of common mistakes committed during geometallurgical programs are discussed and some preferred alternative approaches are suggested

Sep 5, 2011

Adsorption Behaviours of Humic Substances onto Iron Ore Particle Surface Humic substances extracted from lignite mainly consist of fulvic acids (FA) and humic acids (HA), which have been successfully used as good composite binders for iron ore pellets in laboratory tests and industrial production. However, there exists a general lack of understanding of the interaction between humic substances and iron ore particles surfaces. In this research, by means of zeta potential measurements, Fourier Transform Infrared (FTIR) spectrum, colorimetric method and Environmental Scanning Electron Micrograph (ESEM) imaging, the adsorption behaviours of FA and HA onto the surfaces of iron ore particles are investigated. The zeta potential results indicate that adsorption of FA on the iron ore particles can be characterised by specific and electrostatic interactions, while adsorption of HA is by electrostatic and chemical adsorption interactions. FTIR spectrum results show that adsorption force of FA on the iron ore particle surfaces is stronger than that of HA. From results of colorimetric method, compared with HA, adsorption amount and adsorption rate of FA is more and faster, respectively. FA molecule presents on the surface of magnetite in the shape of an araneose network structure according to the ESEM images, while HA molecule appears on the surface of magnetite in the form of small flocs or microclusters. Humic substances are effective to iron ore pelletisation. Comparsion of agglomeration results show that the different mechanisms of adsorption result in varied agglomeration behaviours. Theses findings above would be beneficial to the implications of composite binder for agglomeration.  

Sep 13, 2010

By A F. von Wielligh, M Scott, L Keeney

Operational Grade Engineering (GE) is the early (pre-processing) discard of low-grade mineralised and/or barren rock to improve the ore grade and/or reduce deleterious elements within the run of mine ore to be processed. GE activities generally have an impact on primary and ancillary mining activities, equipment utilization and overall equipment productivity. By discarding material which would have reported as ore (in a non-GE mine plan) means that GE must increases the total ore and total rock mining rate requirements to sustain mill feed targets. One challenge of GE and the planning of GE activities is that there are several indirect parameters which impact operational productivity. Modelling these potential impacts and determining if they can be overcome with alternate mine sequences, equipment application or possibly a different equipment fleet altogether is a key question requiring investigation. Overcoming these potential productivity obstacles associated with a more complex operation by introducing new operational parameters and destinations for ore and possibly sub-grade blocks, requires a GE mine plan that is coupled with detailed equipment productivity metrics and a sound operational plan incorporating all GE infrastructure requirements. Several GE mine plans and equipment productivity models indicate that mining rates generally need to increase by approximately 5% to 15% to sustain mill targets and often negatively impact equipment unit productivity metrices through increased cycle times, additional queuing and destination changes. These changes to productivity metrics are however offset by step change increases in asset value. This paper details a methodology to develop GE mine plans that incorporate equipment modelling, flexible mine sequencing and equipment-based production scheduling. In addition, the paper will outline impacts of GE planning on equipment unit productivities through worked examples and models.

Nov 10, 2020

By PáDeáBosscher, A Bruwier, M Weidenbach, C Philippe, T Ly, A Van Den Bosch

In the mining business the cost of grinding media represents up to 40 per cent of the total milling cost and therefore grinding media optimisation has a direct impact on the concentratorsÆ bottom line. In the process of optimising grinding media alloys, Magotteaux developed its own methodology which consists of a series of analyses, tests, calculations and evaluations and assist the concentrator in optimising their processes.This paper presents the Prominent Hill case study where this methodology has been applied on both the secondary ball mill and regrind IsaMill«.The analysis of the wear conditions in the secondary ball mill allows Magotteaux to select a series of grinding media alloys to be tested to reduce grinding media consumption. By marking these different grinding media types with a unique drilling pattern, one can quantify the relative wear performance and cost effectiveness of each grinding media type within the same milling environment. After selecting the most economical grinding media composition a full scale industrial trial, involving topping up the selected grinding media is carried out and the media wear performance closely monitored and analysed.For stirred grinding mills, suppliers propose different grinding media, mainly ceramic beads, with specific properties and cost. Therefore the concentratorsÆ choice is a compromise between grinding efficiency, wear resistance and cost. The selection of the correct grinding media for stirred milling and the assessment procedure will be presented in this paper. The test results of the new stirred grinding media type in the regrind IsaMill« at Prominent Hill are presented and analysed.CITATION:Weidenbach, M, Van Den Bosch, A, Bruwier, A, Ly, T, De Bosscher, P and Philippe, C, 2012. Forging ahead - A collaboration between the OZ Minerals Prominent Hill Concentrator and Magotteaux to improve plant performance, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 105-110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Lewis RW, Tullemans FJ, Gallo JB

Gold mineralization at Kidston occurs in a semicontinuous zone near the margin of a large, late Palaeozoic breccia pipe. The pipe is ovoid in plan, funnel-shaped in cross section and straddles a contact between Proterozoic metamorphic and granitoid rocks which are intruded by a swarm of late Palaeozoic acid dykes. Rock fragments within the breccia pipe reflect the enclosing country rocks and mix in various proportions to form gradational lithological domains. Most of the gold is free and is located in the breccia matrix and in a set of inwardly dipping sheeted quartz veins which kink around the pipe margin. Sulphide minerals, dominantly pyrite, occur as disseminations in the breccia matrix and as aggregates in the cores of quartz veins. Hydrothermal altLration is pervasive within the breccia and is most intense in areas with the highest percentage of acid dyke fragments. Sericite and carbonate are the main alteration minerals. An empirically developed genetic theory for the formation of the breccia pipe and attendant mineralization involves magmatic and post-magmatic processes associated with the intrusion of a granitoid body to a shallow level in the crust. Economic evaluation of the deposit relied heavily on the results of diamond drilling. Both polygonal and geostatistical reserves were calculated and found to be in close agreement. Geostatistical reserves are considered to more closely reflect the tonnes and grade achievable during mining. Daily geological mine routine is strongly biased towards grade control allied with the practical aspects of open-pit mining. Tonnage/ grade correlations between ore blocks geostat- istically generated from exploration diamond core results and ore blocks generated from high

Jan 1, 1986

By Coates D. F, Neil T. J, O&apos

A proper economic analysis of pit slope design must reflect the trade-off between the benefits and the increased risks of slope fail- ure inherent in steeper slope angles. However, no formal framework for a proper analysis existed to date. This paper describes the results of the past four years' effort in which a formal eco- nomic analysis framework was developed and tested through a case study. This framework, in essence, consists of the availability of tested procedures and com- puter programs. The procedures as well as the programs are divided into two broad functional categories; (1) the first category related to assessing the economic benefits and costs associated with various pit slope angles and (2) the second category that determines the overall financial impact which the assessed benefits and costs exert to the mine operator's overall economic stature.

Jan 1, 1977

By J Yamatomi, Y Tamanishi, S Miwa

The four-dimensional (4D) network relaxation method, originally developed by Akaike in 1999, uses Lagrange relaxation and is known for its ability to include the price change and possible better outputs, but the computation time is huge. However, the continuous advancement in computer technologies allows the use of higher-speed computers with more memory capacity. Therefore, in this paper the authors have tried to implement the method with adjustments and improvements in its algorithm to suit the current computing system. As a result, the computation time has been drastically reduced and more constraints can be included, which makes the scheduling a more realistic one. The case study of an open pit gold mine with 129 500 blocks can be solved considering the capacity constraints in 71 seconds. In previous case studies, the mined ore had to be processed or disposed of immediately. Now, stockpiling can be included as another option. Since the details of the algorithm are still being improved, the computation time is a little longer than the previous cases without the stockpiling option. However, it is found that scheduling with the stockpiling option is possible in a reasonable time. In conclusion, the 4D network relaxation method has become more useful with advances in computer technologies and provides better results.

Sep 26, 2011