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By Georgene Renner, William R. Yernberg, Steve Kral

Agapito Associates (AAI) provides consulting services in geo-engineering, mining engineering and related disciplines. Founded in 1978, the firm operates out of offices in Grand Junction, CO, Golden, CO and Lombard, IL. Members of the staff include mining, civil and geological engineers, physicists, geologists, numerical analysts, computer specialists, instrumentation specialists, plus administration and technical support personnel. AAI has provided consulting and engineering services to mining companies producing base metals, precious metals, coal, potash, trona, limestone, oil shale and salt, and to defense and nuclear-waste disposal industries. AAI also provides services for measuring in situ horizontal stresses using an advanced biaxial overcore stress downhole measurement system developed by Sigra of Australia. Since 1978, AAI has measured in situ stress in copper, oil shale, molybdenum, trona, limestone and coal mines, and in tunnels and concrete structures. Since 1994, the staff has completed 527 overcore stress determinations. AAI has the equipment and personnel for overcoring, sample coring and instrumentation installation in limited access, surface and underground mines. Portable Longyear CP-65 drills, borehole deformation gauges and strain indicators are used for difficult-access overcoring and are permissible for use in gassy mines.

Jan 1, 2006

The selection and implementation of the right technology for a project is critical to the future development of the resource industry. It is essential for companies to ensure ongoing competitive viability that where practical new or alternative technology be adopted. Analysis of historical data relating to development of resource-based process plants provides an enlightening insight into the key factors which influence their success or failure. The adoption of new technology does not guarantee the success of a project. The outcomes of this analysis have been used to develop some general guidelines and principles the author believes are useful in the selection and implementation of new or alternative technology in resource projects. This paper is available as a PowerPoint presentation only.

Jan 1, 2006

By Valentine A. Chanturiya

The aim of this paper is basically to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine noble metals. We studied the influence of nanosecond High-Power Electromagnetic Pulses (HPEMP) on the physical and technological properties of refractory gold-containing ores and beneficiation products. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation, which makes for efficient access of lixiviant solutions to precious metal grains and enhanced precious metal recovery into lixivia during leaching. Preliminary processing of gravity concentrate with a HPEMP resulted in significant increase of gold and silver extraction into lixivia during the cyanidation stage, with gold recovery increased by ~31% (from 51.2% in a blank test to 82.3% after irradiation). Gold recovery from stale gold-containing dressing tailings products increased after pulses-irradiation from 8-12% to 80-90%.

Jan 1, 2006

By Kot F. v. Unrug

The present combination of coal market prices and reserves, situated in the Central Appalachian Coal Field, is such that mining of smaller coal reserve blocks has become economically attractive. In above drainage deposits, and particularly under mountain ridges, overburden depth can be changing within a wide range. Mines operating in these deposits are usually developing mains along the center of the ridge, with panels projecting from the mains towards the outcrop. Due to changing topography, proximity of the outcrop, and related cover depth, the panels have various lengths. In this reported case study, a mine in Pike County, Kentucky, along the Kentucky ?West Virginia border, difficult ground conditions were encountered, during the development of the mains, under shallow cover, along a narrow mountain ridge. An area having unusual density of vertical joints was encountered. Mining operations were suspended because of roof stability concerns. The ground conditions were studied, analyzed, and control measures proposed to ensure safe passage through the difficult roof area of the mine. The advancement of the mains, through this area of challenging ground conditions, was successfully completed. In this paper, ground conditions are described, with an explanation of the geologic process contributing to their formation. It is interesting to note that similar locations were predicted by the authors, to be encountered in the same mine, based upon the experience gathered from studying conditions of the case described within this paper. When approaching the predicted locations, stability problems appeared to be even more challenging than those encountered previously. Due to changes in the coal market, mine management chose to move the affected mining section to another area of the mine having better coal quality. The advancement of the mains, through the difficult ground conditions, was temporarily postponed. Based upon the analysis of a probable kinematical mechanism of blocks in the mine roof, ground control measures were proposed. The actual application of these principles proved to be appropriate, ensuring safe passage through the difficult ground conditions encountered in the mine.

Jan 1, 2006

By C Glassock, P Tilyard, T Sandeman

Computer simulation is a well accepted tool for modelling the behaviour of large and complex operating systems. It is a particularly useful technique in complex operations where there are multiple interactions between the inputs and outputs of various unit operations. It can be utilised during the early stages of a project as part of the business case definition phase or the early engineering phases, or alternatively to help understand the various options available in an upgrade or expansion. With the design of a new processing plant to handle a different ore type at Lihir Gold Limited (Lihir), there was concern that the existing conveying system could separately handle the increased tonnages. A simulation model was constructed which allowed Lihir to examine the impact on the conveying system of the new process plant, as well as investigate the effect of different trucking options. As is often the case, once the simulation model was built, further understanding of the downstream bottlenecks was able to be investigated, including the sizing of critical equipment.

Jan 1, 2006

By Mika Muinonen

"Dewatering of nickel concentrate at the INCO Thompson integrated mine-metallurgical site takes place within the smelter plant. The eight original 60 foot diameter cable torque thickeners of which four were operational and eight Dorrco internal drum filters have been replaced with a single Outokumpu high rate thickener and a single Lasta pressure filter. The modernization has resulted in a filter cake which has a more stable and lower moisture content. Control of the entire dewatering process has been improved and costs have been reduced.Typical filter cake produced from the Dorrco filters during processing of high tonnages of Birchtree mine ore was ~20% moisture vs. ~13% moisture for concentrate produced from the Thompson mine ore. The high moistures were correlated with the amount of fine magnesium silicate gangue in the concentrate. As Birchtree ore processing rates have increased, this filter cake moisture became unacceptable because of material handling problems and the impact on furnace metallurgy. The Dorrco filters were replaced with the Lasta filter in 2003 that has consistently produced filter cake at ~11% moisture.This paper summarizes the piloting, design, installation and commissioning of the modernized dewatering circuit.INTRODUCTIONThe Thompson integrated nickel processing facility was built in 1958 and originally consisted of a mine-mill-smelter and, soon after, a refinery.Nickel concentrate is pumped from the mill as a dilute slurry directly to the smelter facility ~200 meters along an unheated pipe trestle. Originally, nickel concentrate was de-watered using up to 8 conventional 60-foot diameter thickeners and 8 internal vacuum drum filters."

Jan 1, 2006

By N. Shi, T. G. Joseph

The design of dippers for cable shovels has essentially remained unchanged for the last 100 years. In the past 10 years, shovel manufacturers have started taking another look at dipper design, resulting in changes that have borne models from major manufacturers that address some of the wear conditions and material retention problems that dominate maintenance and operational costs. However, with the exception of added lateral curvatures to the front and corners of the dipper, the geometry is essentially unchanged. This paper looks at the criteria that have resulted in the first new cutting dipper design in a century. The design is based on kinematic considerations, reflected in a revolutionary geometry that matches the range of motions of the shovel, designed to minimize wear, impact loading and power required to dig, thus maximizing productivity for a minimum energy requirement. The shape configuration is such that the weight of the dipper is reduced through wall thickness, enabling a larger capacity dipper to be conceived for the same shovel. Benefits are reflected in reduced operational and maintenance costs and increased productivity.

Jan 1, 2006

By Xi Zhang

A technique for fabricating free-standing, high-aspect-ratio porous and pillar-type Ni structures has been developed using wet Si processing. A wafer of (100) Si was initially etched in HF solution to form deep pores with micron-sized diameter. The aspect ratio can exceed 200. By introducing the as-etched Si into a defined aqueous Ni2+ solution, Ni deposits grew rapidly onto the sidewalls and replaced the Si. Long-time immersion allows the Si sidewalls to be completely converted and thus form a metallic Ni structure with high-aspect-ratio pores. It is known that close-packed submicron Si pillars can be formed by oxidizing and subsequent etching of the macropore sidewalls. Treated in the same Ni solution, high-aspect-ratio Ni pillars were correspondingly emerged by replicating the original pillar-type Si structure.

Jan 1, 2006

By A. L. D. Skury

In the synthesis of diamond, the precursor graphite must present a degree of crystallinity to assure optimum yield and quality for the transformed crystals. X-ray diffraction, SEM and TEM analyses were carried out to investigate the structural and morphologic transformations produced in natural graphite by high pressure-high temperature treatment. The present study had as its objective to characterize the morphological and structural changes suffered by a natural graphite that was subjected to high pressure and high temperature treatments in the region of diamond thermodynamic stability. The results indicate that the material that constitutes the gasket, for the deformable capsule, could act as catalyst in the graphite recrystallization process.

Jan 1, 2006

By V. Coetzee

Keywords: Pyrometallurgy, furnace, PGM, platinum, nickel, copper, electric smelting, six-in-line, Peirce-Smith, Impala Platinum In 1992, a paper was compiled highlighting a common-sense approach to electric smelting at Impala Platinum. Since then, the smelter complex has undergone considerable changes. Mineral economics, UG2 exploitation, and changing environmental legislation have enforced numerous process upgrades, yet a common-sense approach has always been adopted. This document details the major changes in the smelter complex at Mineral Processes (Minpro) over the past 15 years, and provides the rationale for the changes.

Jan 1, 2006

By B Mil, D P. Adhikary, M S. Craig, P Rutzou

As shallow coal reserves with easier mining conditions are exhausted, future deep coal mining with difficult mining conditions may face significant economic, technical and environmental challenges. Moreover, due to increased coal production capacity with the new generation longwall systems, predicting adverse mining conditions has become more important than ever before. The potential impact of these difficult conditions is an increase in mining risks and costs. Reliable prediction of rock mass deformation, mine stability and mine water inflow is not only essential for improving mine safety and reduction of coal production costs, but it is also important for the assessment and management of the environmental impact of mining. This paper briefly describes an integrated approach to mine groundwater simulation and prediction. Central to this integrated approach is a three-dimensional computer code called COSFLOW, developed by CSIRO of Australia in collaboration with NEDO and JCOAL of Japan to address the pressing issues of mine water management. COSFLOW incorporates unique features that make it ideal for the simulation of coal mining and examining the interaction between rock fracture, aquifer interference and water flow. This paper also presents an example of an application of the integrated approach and COSFLOW in water inflow prediction at Springvale Mine in New South Wales.

Jan 1, 2006

By D S. Perera, P Wal, D C. Southam, J L. Lowe

The Cooperative Research Centre for Sustainable Resource Processing (CSRP) is undertaking a large research project involving partners from industry, universities and government, which aims to develop the necessary chemical and structural understanding of geopolymer materials made from waste products for them to be used to capture a significant market share of the concrete business for a given industrial region. We are investigating the suitability of a range of soluble silica-bearing waste streams for use as geopolymer concrete feedstocks. In order to utilise a variety of waste streams, either singly or blended, an understanding of the role of secondary metal ions (Fe, Ca, Mg, Ti, etc) in the geopolymerisation process is essential. A range of experimental and analytical techniques is therefore being used to better understand the structure-chemistry-property relationships of geopolymers. Currently, we are investigating geopolymers made from a variety of waste streams (fly ash, kaolinite, red mud, etc) available in the Kwinana Industrial Region, Western Australia. This paper will detail how the basic scientific research underpinning the project is vital if waste streams of varying composition are to be successfully used in a commercial concrete product and the regional synergies required to develop geopolymers from waste streams.

Jan 1, 2006

By Peter Deming

"PART 1 OF 2INTRODUCTIONSlurry trenches are the least cost hydraulic barrier available, if the excavated spoils can be recycled into backfill. As such, slurry trenches are constructed where possible, sometimes at high risk. Slurry trenches are also used to install biopolymer drainage trenches, which have a low safety factor because the biopolymer slurry weight is marginally greater than the weight of water. In marginal ground the construction risk falls to both the Owner who designs and asks for the construction, and the Contractor who manages the work and promises to complete the project successfully. This paper discusses design and construction of slurry trench barriers in marginally stable ground and where groundwater chemistry invokes the need for slurry management details to obtain proper backfill placement.As a designer, Mueser Rutledge Consulting Engineers works for both Owners and Contractors. We are usually able to convince Owners of their responsibility for design detailing in order to obtain a working final product and to obtain reasonable bids from Contractors by disclosing construction needs and designing to reduce the contractor’s exposure. We often work for Contractors to produce designs which result in successful construction in projects where the Owner’s engineer places the responsibility of design and construction on the Contractor.This paper is intended to inform both Owner and Contractor audiences of resources which are available to reduce the risks of trench collapse in difficult ground conditions. We hope it serves this purpose.DESIGNSubsurface InvestigationsSubsurface conditions should be defined by borings focused on definition of the soil profile and soil design parameters. After general subsurface conditions are defined, barrier borings should be drilled along the final alignment.Definition of Soil Strength and CompactnessCompactness of sand and gravel strata should be defined with Standard Penetration Test N-values. The shear strength of cohesive materials should be defined by laboratory testing. Silt and fine sand strata with little cohesion should be investigated using mud rotary techniques to prevent disturbance. General strength characterization by soil layer should be used for analysis of trench wall stability."

Jan 1, 2006

By R Whittering, C Greet

High chrome grinding media has been used in the mining industry for quite some time, as it often proves economical on a wear basis. However, it is unusual for an operation to change to high chrome solely due to its metallurgical benefits. KagaraÆs Mount Garnet operation made the change from forged steel to high chrome media after laboratory testwork indicated that copper grades and recoveries would improve. The outcome was remarkable with positive changes in pulp chemistry throughout the circuit accompanied by marked improvements in copper, lead and zinc grades and recoveries. Reagent dosage rates were reduced, often by more than half, and the grinding media wear rate dropped to less than a third of the wear rate of the forged steel media. The economic analysis showed that out of the total increase of revenue and savings from metallurgical improvements and reagent and media consumption reductions the metallurgical improvements made up approximately 73 per cent, the reduced reagents saved 25 per cent and the savings through reduced media wear contributing by just over one per cent. This indicates that the popular view of high chrome media only being trialled in the plant for wear economics is outdated and the focus of operations should be shifted to using high chrome media for the metallurgical benefits.

Jan 1, 2006

By Ross Nairn

"Tulawaka Mine is a joint venture between Pangea Minerals Limited 70% (a wholly-owned subsidiary of Barrick Gold Corporation) and Northern Mining 30%. Tulawaka Mine is located in North West of Tanzania in the Lake Victoria Goldfields. Tulawaka Mine is scheduled to process 360,000 tonnes per year at an average 11.5 g/t head grade over a 4 year mine life.The Tulawaka Process Plant uses single stage crushing, single stage SAG milling, gravity, intensive leach of gravity concentrates, CIL, Zadra desorption and cyanide detoxification to process the ore. Gold recovery exceeds (or is expected to) 95%.The Process Plant was designed and constructed under the supervision of Ausenco Engineering of Australia. Site works commenced in January 2004, Process Plant construction commenced in July 2004 and the first ore was presented to the Process Plant 26th February 2005. The first gold was poured on 15th March 2005. All construction contractors were demobilized from site 7th April 2005. Major achievements have been 3.4 million hrs LTI free during construction and operation to date, training of the Tanzanian workforce at Bulyanhulu Mine prior to commissioning, a succession plan to replace expatriate personnel with Tanzanian staff and significant over performance of the Process Plant against design.INTRODUCTIONTulawaka Mine is situated approximately 160 km south west of Mwanza in the western Lake Victoria Goldfields District of north western Tanzania. The property is held under a joint venture between Pangea Goldfields Inc (70%), a wholly owned subsidiary of Barrick Gold Corporation, and Explorations Minieres Du Nord Ltée (30%). A location map showing the position of the operation in Tanzania is shown in Figure 1.Mine site staff at Tulawaka comprises a combination of Tanzanian and Expatriate personnel. All Pangea personnel live on site and commute to their place of residence for their R&R on a 9 weeks on 4 weeks off roster."

Jan 1, 2006

By P. Middendorp, Gerald E. H. Verbeek

"INTRODUCTIONStatic Load Testing (SLT) is generally considered the pile testing method that provides the de-facto answers regarding pile capacity and load-deflection behavior. However, as this testing method is time consuming and costly, alternative pile testing methods are applied, such as High-Strain Dynamic Testing (HSDT), commonly referred to as Dynamic Load Testing (DLT), and Rapid Load Testing (RLT), which includes Statnamic Testing (STN) and the Fundex Pile Load Tester (PLT). Extensive descriptions of these pile testing methods as well as comparisons of the results from these two methods have been widely published, but little is written on the choice between HSDT and RLT. This article will address this issue for concrete piles by discussing five different aspects that should be considered when making a choice between HSDT and RLT for either cast-in-situ piles or precast driven piles. TIMINGThe timing of the pile load test is independent of the testing method. For cast-in-situ piles load testing is performed some time after the pile has been installed (to allow the pile to obtain the compressive strength required to withstand the test load), while for precast driven piles load testing is performed after a so-called set-up period following pile installation (to allow the soil to recover from driving induced disturbances and, at least in most cases,regain strength).In other words, the timing of the test does not affect the choice of the testing method.ACCURACY OF THE APPLIED LOADWhen a pile is tested by RLT the applied load is measured by a calibrated load cell placed on the pile head, just as it would be during SLT. This means that the error in the applied load value is less than 0.1% of the maximum range of the load cell.However, when a pile is tested by HSDT the load is calculated from the measured strains, which means that the outcome is dependent on the pile material properties. In this case the applied load (F) on the pile head is calculated by multiplying the measured strain (?) with either the calculated or estimated elastic modulus of concrete (E) and the pile cross section (A).The elastic modulus is generally back calculated from the (average) stress wave velocity (c), which in turn is derived from the reflection time (T) it takes for a stress wave to travel over the pile length (L) from the pile head to the pile toe and back to the pile head."

Jan 1, 2006

By R Norris, M Dunne

Substantial efforts by the industry, as well as by process and equipment designers, have resulted in many innovative developments that provide cost effective reductions in water usage. This paper showcases four emerging best practices in industry including examples of recent installations. Belt press filters are a small fraction of the operating and capital cost of alternative ædryÆ tailings technologies. This gives operators who must ædryÆ their tailings a competitive advantage and makes such operations much more sustainable. The new generation of belt filter presses use less energy, produces lower cake moistures and better disposal stacking properties. The need for tailings storage facilities may be eliminated or in some cases high-grade tailings can be dewatered and sold as a low value product. Mining applications include sand tailings, sinter plant waste, coal tailings and power station fly ash. Flip-flow screening machines are proven worldwide in the dry classification of coal and other minerals, reducing the size of beneficiation plants, whilst reducing energy, water demand and media consumption. They also allow the screening of wet/sticky materials not able to be sized using conventional screens. Lamella separators are used for toxic water clarification and/or sludge thickening in many downstream metal industries with the underflow often dewatered in a belt filter press. Such low cost, high capacity thickeners could also be used instead of conventional thickeners at smaller mines. The simple and reliable continuous washing upward flow (CWUF) sand filters have been used for treatment of waste water from coal preparation plants and steel works as well as in the production of potable water. The filtered waste water from mining processes can then either be reused or discharged from site. Other installations include cleaning mine water to prevent the blocking of dust suppression spray nozzles.

Jan 1, 2006

By Bowen Li

Silicon Carbide is an excellent refractory material. Its physical properties make it extremely useful, particularly in applications where corrosion resistance and wear are important considerations. Commercial silicon carbide refractory is frequently manufactured by bonding silicon carbide particles with clay; however, clay may cause problems in the sintered products. This study investigates the potential of replacing a portion of the clay with andalusite powder. The results show that micron size andalusite powder can improve not only the strength of the refractory but also the sinterability. The mechanisms for these improvements are discussed.

Jan 1, 2006

By R Wolff

One critical factor in open pit mining projects is the estimation of the recoverable reserves. The reason for this is that at the valuation stage there is a lack of information about future metal prices and production costs. Consequently, the estimation of the recoverable reserves needs to be done based on a fixed break-even cut-off grade (BECG), in which fixed expected metal prices and production costs are assumed throughout the operating life of the mine (OLM). In this paper, an alternative technique for estimating the recoverable reserves of an open pit mining project is presented and explained in detail. The main characteristic of this technique is that it estimates the recoverable reserves of the project using mining costs as reference: this is done due to the fact that mining costs are easier to model than metal prices. Another important characteristic of this technique is that it uses the uncertainty of the geology of the orebody, given by simulations of the deposit, to make final strategic decisions, such as the selection of the operating life of the mine and the optimal production rate, which minimise the risk of not achieving future production targets while maximising the upside potential of future rewards. As it will be shown, the final outcome of the proposed technique is the generation of a robust open pit design, that include cutbacks and ultimate pit limits, called the marginal open pit mine design (MOPMD). One characteristic of the MOPMD is that, at each production period, it will be characterised by their respective geological uncertainty, given as probability distributions of ore, waste and metal quantities, and by marginal economical project indicators, such as cut-off grades and metal prices, among others. The details follow in the paper.

Jan 1, 2006

By N. Shariatmadari

In recent years, determining bearing capacity of piles from in-situ testing data as a complement of static and dynamic analysis has been used by geotechnical engineers. In this paper, different approaches for estimating base bearing capacity of piles from SPT data has been compared and evaluated. A new method for pile base bearing capacity in sand is proposed using SPT records. Data averaging, failure zone extension, and plunging failure of piles have been addressed in the proposed approach. A data bank comprising 10 full scale static load tests on instrumented piles and 26 dynamic tests, analyzed with signal matching technique by CAPWAP software, was used for validation. The SPT data that was performed close to pile locations is also included in the data base. Comparison of current methods by error investigation with Log-Normal approach demonstrates that the proposed method predicts pile base capacity with more accuracy and less scatter in comparison to other methods.

Jan 1, 2006