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By L O. ÆNeill, J Bebek

When Kalgoorlie Consolidated Gold Mines (KCGM) purchased its fleet of 18 CaterpillarÆs dump trucks in 1999, as part of its change to owner operated mining, five CaterpillarÆs Computer Aided Earthmoving Systems (CAES) were also commissioned on Komatsu PC8000 hydraulic shovels and Caterpillar D10R bulldozers. Since then the CAES system has been installed and operational on Komatsu PC3000 hydraulic shovel, CaterpillarÆs D10R dozers and Cat 994 front-end loader while Cat 854 wheel dozer has been fitted with CAESbasic. This investment in advanced machine guidance and control technology has proven very beneficial over the years for the Super Pit with improved safety and increased operating efficiency and productivity. The paper brings into focus how the CAES system adaptation in unique mining conditions assists in production gain, equipment operatorÆs safety, flexibility and independence, personnel removal from hazardous areas, acquisition of operational information and improvements in mine planning and design, benefiting the entire mining operation.

Jan 1, 2003

During the first five years of operation, the Lihir gold mine has steadily increased plant throughput rate to over 4 Mtpa, well above the original design capacity of 2.8 Mtpa. Understanding how future variations in ore type impact on plant performance has been an integral part of LihirÆs development program. This paper discusses the key drivers for significant improvements to the plant, including a second oxygen plant, a pilot flotation plant, an autoclave heat recovery circuit, a pebble crushing circuit and additional autoclave feed pumping capacity. The result is a process plant with the flexibility to accommodate variations in ore type without significant loss of throughput.

Jan 1, 2003

By P Wigley

New methods of analysing and modelling flotation circuits have been developed as part of the AMIRA P9 mineral processing research project. A study using these techniques was conducted on the Olympic Dam copper flotation circuit to provide the following outcomes: an estimate of the flotation cell hydrodynamic properties and froth performance characteristics, and identification of potential areas for improvement; an estimate of the feed floatability parameters for basic model development; and identification of potential flotation circuit improvement opportunities. A flotation circuit model of the Olympic Dam copper concentrator was developed using the data collected from mass balanced site surveys, along with hydrodynamic data, froth performance data and numerous laboratory batch flotation tests. The simulator that has been developed from the model has the ability to estimate the influence of selected changes (such as circuit changes) on flotation circuit performance. Several stream destination simulations were conducted to provide guidance for further testwork and possible circuit improvements. The results from these simulations are presented.

Jan 1, 2003

By J Brisebois

The derelict Lake George Mine is located at Captains Flat in NSW, acommunity of approximately 450, which lies some 43 km southeast ofQueanbeyan. It straddles the Molonglo River, which flows toQueanbeyan and thence the nationÆs capital, Canberra. Catastrophictailings dam failures in 1939 and again in 1943 resulted in the transportand dispersion of thousands of tonnes of sulfidic wastes downstream,with terminal settling in Lake Burley Griffin, in Canberra. The mine wasclosed in 1962, and major rehabilitation in 1996 - 1997 addressed the riskof further collapses, and reduced water flow into the underground mine.Nevertheless, acid mine drainage from the mine, and seepages ofcontaminated water from the capped tailings dumps continue to pollutethe Molonglo River for some 30 km downstream.Environmentally, the highest contributor to the total contaminant loadof the river is the Main Adit Spring. This was shown to be a constantgroundwater-driven acidic flow, with contaminant generation resultingalmost entirely from the ingress of gaseous oxygen into the undergroundworkings. Long term remediation may be possible at source, by pumpingreducing gases into the sealed mine, but the probability of thistechnology succeeding to the required degree is yet to be demonstrated. For at least the medium term, treatment of contaminated water flow(s)will be required to achieve any of the water quality targets that may beapplicable to the river. Three methodologies were short listed, but anumber of strategic uncertainties remain, which the NSW Derelict MinesProgram will address. Future risk arising from long-term contaminantrelease by the treatment wastes must be considered. Appropriate data,and realistic long-term performance parameters regarding the relativestabilities of water treatment sludges are scarce, and make properevaluation of competing technologies problematic.

Jan 1, 2003

The Awareness and Preparedness for Emergencies at the Local Level (APELL) program is a process that helps people prevent, prepare for and respond appropriately to accidents and emergencies. APELL was developed by the United Nations Environment Program, in cooperation with industry groups, governments and local communities. Since its beginnings in1988, the program has been implemented in more than30 countries. APELL is a tool for bringing people together to allow effective communication about risks and emergency response. The program provides a common-sense approach to accident prevention and response.

Jan 1, 2003

Blasting is a common practice in mining whereby solid rock is fractured, using explosives, to a more manageable size. The effectiveness of blasting influences a number of downstream activities such as shovel digability, crusher throughput and mill throughput. As the cost of explosives is relatively low compared to milling costs (mainly due to power consumption), blasting practices can be optimised so that the downstream processes are made more efficient, and an overall cost saving made. This is the basis of the Mine to Mill approach. The effectiveness of the blasting is influenced by two main factors, the blasting practices used (eg explosive amount and type) and the geology of the area. As the geology cannot be altered, the blasting practices must be refined to create optimum blasting. Kalgoorlie Consolidated Gold Mines (KCGM) Fimiston operation, located in the heart of the Kalgoorlie Goldfields is the largest gold mine in Australia. Mine to Mill at KCGM has had varied success, with initial positive indications being lessened by a number of factors, including the increase in the amount of voids.

Jan 1, 2003

By Victor M. Mercado, Jay B. Shah

Spalding DeDecker Associates, Inc. (SDA) designed a tunnel project that fulfilled the Sustainability Objectives of Social Equity, Environment, and Economics. The project translated the principles of Sustainable Development into actions that lessened the impacts of construction on environment, lives of residents, businesses, traffic, and other social systems (i.e., shopping, recreational, and educational). The project involved the construction of a 16,108 feet of 84 inch diameter sanitary sewer interceptor by tunneling 40 feet beneath the ground surface through difficult geological and hydrogeological settings. An effective public information and stakeholders relationship program was developed to achieve the stated objectives of sustainability.

Jan 1, 2003

By Takahiko Okura

Most non-ferrous raw materials are associated with sulphur. To extract the metals, the sulphur is recovered typically as Sulphuric acid or liquid S02. On the other hand, natural gas may contain over 20% of hydrogen sulphide (H2S) and a huge quantity of elemental sulphur is produced through oil and gas refining processes in the world. A large fraction of the sulphur mined from natural sources is eventually returned to the earth as fertilizers, by-products of desulphurisation and neutralisation processes, or as fugitives to the atmosphere. However, the supply and demand for sulphur are in imbalance. Such situation urges to develop a new smelting process without sulphuric acid production. This paper briefly reviews the global sulphur balance and the technologies for recovering elemental sulphur. The core of this paper is a proposal to convert S02 gas to elemental sulphur by using organic materials. Some results of thermodynamic calculations and experiments are presented.

Jan 1, 2003

All large open pits in Australia have been mined, or are planned to be mined well below the local water table. This raises several issues that impact on mine safety, mining costs and regulatory approvals. Some pits will be æwetÆ, where they are mined through permeable horizons and where there will be measurable groundwater inflows. These will require some form of dewatering. There may also be some difficulties in the disposal of excess water. Other pits, may be ædryÆ, where they are mined through impermeable material and there are no measurable groundwater inflows but where there are stability issues related to hydrostatic pressures within the pit walls. These may require some form of depressurisation. Some pits are a combination of both. Effective management of groundwater inflows and groundwater related stability issues and the development of cost effective and environmentally acceptable dewatering and depressurisation systems requires an understanding of site specific hydrogeological conditions and practical experience in what works best for different conditions. The presentation will include an outline of the key hydrogeological factors that impact on large pits, practical methodologies for achieving dewatering/ depressurisation, and some case studies from the Goldfields, Pilbara and North Queensland.

Jan 1, 2003

By Del Brock, Dan Wooton

The design/build of two adjacent vertical mine shafts in difficult ground conditions at a mining complex in the midwestern United States required innovative construction techniques. Construction of the 267-m-deep Service Shaft required full depth dewatering wells and ground freezing. Blind drilling was utilized to excavate the 257-m-deep Production Shaft and it was finished with a steel/concrete composite liner that was floated into place. An equally unique component of the installation included supplying a high capacity vertical conveyor system, featuring a 273-m-lift. Other components of the project include the mine level development, as well as the design and installation of three hoisting systems, including a 45-ton capacity men/materials hoisting system.

Jan 1, 2003

By Satoshi Itoh

Phase equilibria and activities of the components in the liquid lead-antimony-oxygen ternary system, which is of fundamental importance for discussing the' recovery of lead and antimony from a used lead-battery, have been investigated at 1173 and 1223 K. The two liquid phases of metal and oxide were observed at the temperatures studied, and the tie lines indicating isoactivities were determined. The activities of PbO, SbO1.5 and Sb2O3) in the PbO-SbO1.5 and PbO-Sb2O3 pseudo-binary systems were then obtained by applying the Gibbs-Duhem equation to the phase relation of metal-oxide equilibrium. Both in the pseudo-binary systems the activities exhibit negative deviations from Raoult's law. The vapor pressures of lead, antimony and lead oxide, antimony oxide were calculated by using the activities of the components in the lead-antimony-oxygen ternary system. As a result, an oxidation of antimony concentrated in an anode slime followed by evaporation as antimony oxide Sb406 was found to be considerably effective for the recovery of lead and antimony from a used lead-battery.

Jan 1, 2003

By C Kusi-Manu, E Nyamusika

Geita Gold Mining Limited (GGML) is owned and jointly managed by Ashanti Goldfields Company (Ghana) and Anglogold (South Africa). The mine is currently one of the largest gold producing open pit operations in Africa producing 620 000 ounces of gold and mining in excess of 70 000 000 tonnes of material per annum. The mine currently has 2000 full time employeeÆs and a mine life in excess of 12 years. Geita Gold Mine is comprised of 11 different gold deposits situated in the Lake Victoria Goldfields of North Western Tanzania (Figure 1). The gold deposits are primarily associated with banded ironstone formations within an Archaean greenstone belt. Current global resources, including Inferred, stand at 129.5 million tonnes grading 3.91 g/t (16.2 M oz). Open pit reserves total 70.4 million tonnes grading 4.16 g/t (9.4 M oz). The majority of the gold resource is hosted by the three deposits (Nyankanga, Lone Cone and Geita Hill) within the æGeita TrendÆ a large and continuous (>4 km long) mineralised zone (Adofo, 2002). Geita Gold Mine commenced operations in June 2000, as the second large-scale open pit gold mine in Tanzania. The new workforce of 800 people had no previous experience in open pit gold mining. Since the start of the operation, Geita Gold MineÆs management ambition was to become a world leader in the application of best practice in all technical disciplines and in operational success. Staff development and training was identified as one of the major components in the company achieving its aim. Geita Gold MineÆs management has committed the necessary training staff, resources and the commitment of over $US 1 M a year to staff training and development programs for 2003 and 2004. The process and management of Geita Gold MineÆs mining geology staff training and development program is presented in this paper.

Jan 1, 2003

By G M. T, M Zh Bitimbayev, F K. Shadiyev

In the paper a complex problem was formulated for studying and establishing an effective and safe technology of selective underground leaching of useful components from polymetallic ores. Solving this problem will allow increasing technical and economic efficiency, technological and ecological safety of mining of useful minerals of polymetallic deposits.

Jan 1, 2003

By David Corkum, David Hatem

Subsurface construction projects are risky ventures and the decision to deliver a project using the Design-Build model does not eliminate those risks. Differing site conditions, inadequate design, and delays will continue to plague some projects. The Design-Build procurement model, however, presents a broad opportunity to allocate those risks much differently than in the familiar Design-Bid-Build model. Starting with a philosophical approach to risk and reward, this paper discusses the continuum of possible risk allocation strategies. It concludes with a proposed optimum strategy in terms of the project’s overall economic efficiency, and points to the dispositive contractual provisions that serve to contour the risks.

Jan 1, 2003

By Bruce Hebblewhite

An ACARP-funded industry research project in Australia recently investigated the problem of premature rock bolt failures in underground coal mines. The project carried out limited sampling from 9 different collieries in NSW and Queensland, followed by a more comprehensive, controlled sampling from one colliery. Over 50 broken bolts were collected and subjected to metallurgical analysis at UNSW to determine both the steel composition and to analyse the fracture surfaces. Prior to this study, there had been anecdotal evidence of similar bolt failures from a number of sites within the industry. The sampling and analysis conducted by this project - whilst being below a statistically representative sample of the entire industry bolt population - highlighted the fact that bolt failures were continuing to occur at a number of sites, in both older and recently installed bolts. The failures were almost entirely attributable to stress corrosion cracking (SCC). It appears that a combination of factors - including steel composition, bolt manufacturing process, loading environment, geological and hydrological environment, bacterial corrosion - can all contribute to this problem. There is no simple solution, however, as with similar research findings from the UK, it appears that steels with higher values of fracture toughness, or Charpy Index, are less susceptible to SCC. Testing to date has been limited to bolt failures below the resin encapsulation horizon. A real concern is the potential extent of the problem at higher horizons, within the encapsulation. These may require some form of non-destructive testing (NDT) for detection. Initial trials in Australia of the ultrasonic device developed by DMT in Germany have proved encouraging. Further testing using this device is anticipated in future research. This paper describes the outcomes of the project, completed in 2002.

Jan 1, 2003

By Brajendra Mishra

Molten Salt electrolytic processes offer unique opportunities to extract and refine metals where gaseous or metallothemlic reduction, hydrometallurgical extraction and aqueous electrolytic methods are thermodynamically constrained. Production of aluminum and magnesium by molten salt electrolysis are well known commercial processes. Several other reactive metals, such as lanthanides and actinides, as well as beryllium and calcium, make use of molten salt processing for extraction and refining. This presentation describes the science of molten salt chemistry and electrochemistry for winning and refining of several metals. In addition, recovery of metals from waste process salts by molten salt reduction as well as oxidation have been discussed. Material issues in design of molten salt reactors have been included. Various applications have been presented through case studies. Experimental data have been included to justify the suitability as well as limitations of these specific processes.

Jan 1, 2003

By H Plewes, A Bur, L Murray, J Pottie

Water recovery from tailings for reuse in mineral processing is essential to operation of mines in the Atacama Desert of Chile. With annual rainfall of 5 mm, the prudent and efficient use of available water resources is a major issue for the Escondida Mine and other mines in the area. The Escondida Mine is located at an altitude of 3100 m, in a very arid, seismically active part of the Atacama Desert of northern Chile. The site is located about 170 km from the coastal city of Antofagasta. From 1994 to 2002, tailings were discharged into the Hamburgo Tailings Facility, which comprises a series of æpaddiesÆ located near the open pit and mill. Because water in the region is only obtainable from groundwater sources, the paddy system incorporated a number of design features with the aim to maximise water recovery from the tailings. As part of the recent mill expansion to 237 500 metric tonnes per day, a new tailings facility, the Laguna Seca Tailings Facility, projected to be one of the largest tailings facilities in the world, was commissioned in 2002. Extensive studies were conducted for the design of the new facility to predict water recovery from the conventional wet disposal of tailings. The predictions were calibrated against the performance of the Hamburgo Tailings Facility and subsequently re-calibrated against actual performance during the first year of operation at the Laguna Seca Tailings Facility. Initial operation of the Laguna Seca Facility was marked by a coincidental change in tailings characteristics from design, which highlighted the need for thoroughly understanding tailings behaviour during deposition, and the parameters and deposition techniques that could enhance water recovery. Systems have been put in place to manage the tailings deposition and respond to changes in key parameters such that water recovery targets can be reliably achieved. This paper describes the background studies that were conducted to evaluate evaporation and tailings behaviour, summarises the water balance and then presents some observations from the commissioning and start-up of the facility.

Jan 1, 2003

By R L. Verburg, R Johnstone

DeBeers Canada Mining Inc (DeBeers) recently submitted an Environmental Assessment (EA) for its proposed Snap Lake Diamond Mine located in Northwest Territories, Canada. As part of the EA process, a site water quality management plan must be developed. Plan development requires an integrated approach such that the key factors influencing water quality can be identified and managed to minimise potential impact. A system model was therefore developed to simulate the site-wide water quality conditions and mass loadings to the principal environmental receptor of concern, Snap Lake, during operations and post-closure. Requirements of the simulation included integrating hydrology, geochemistry, hydrogeology and site management practices in a dynamic way. A unique feature of the site was the need to accommodate a complex flow system that included a feedback loop between lake water and mine water. A system model was constructed using the GoldSim software package that integrated on-site water quality and flow measurements, as well as results from independent groundwater flow and geochemical modelling efforts. The GoldSim model simulated concurrently the movement of 39 solutes through the subsurface mine and surface facilities. Solute sources considered included four different waste rock and tailings types, explosives use in the mine, treatment plant discharge, and recycled process water for dust suppression. Separate solubility constraints were identified for different regions of the flow system (eg underground mine; treatment facility; surface water bodies). Kinetic test data were used to derive temperature-dependent rate constants for use in calculating mass inputs from surface sources such as waste rock piles. The model generated water quality estimates over time for a variety of management scenarios at several potential discharge locations. The integrated approach used by the model was effective in identifying the significance of key factors influencing overall water quality such as explosives use, mine water inflow rates, waste rock reaction rates, site/mine management options, and effectiveness of treatment. The model provides an example of an effective tool for comprehensive, integrated system evaluation and management.

Jan 1, 2003

By Michael Karmis

The International Conference on Sustainable Development Indicators in the Mineral Industries(SDIMI 2003) was held May 21-23, 2003 on the island of Milos, Greece. The objective of this international conference was to assist the mining and minerals industries in their global transition to sustainable development. The main theme of the conference was the development, monitoring and assessment of sustainable development criteria for mineral operations. Emerging technologies were also presented that can assist in the development of criteria and performance indicators.

Jan 1, 2003

By Varadarajan Seshadri

The performance of mould fluxes in satisfying its quality requirements can have a significant effect on the efficiency of the continuous casting process and on the surface quality of the products. This performance is affected by various parameters including the characteristics of the mould fluxes, the quality of the steel being cast and the operational conditions of the caster. The extremely complex relationships involving the parameters mentioned above make it very difficult to have simple criteria for selecting mould fluxes for casting a certain grade of steel in a continuous casting machine. These difficulties led steelmakers and mould flux suppliers to select mould fluxes based mainly on plant trials. In the present work, a software to help in the analysis and development of mould fluxes for continuous casting was developed_ This software includes several models for prediction of mould flux viscosity and consumption. A mathematical model was also used to predict the heat flux through the mould flux. The proposed methodology was applied to continuous casting of crack sensitive steels_ Some of the results given by this software are presented, discussed and compared to plant data.

Jan 1, 2003