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By B J. Monaghan, P Zulli, X F. Dong

In the lower zone of blast furnace (BF), slag trickles down through a packed bed of carbonaceous particles in the form of films, rivulets or droplets. During its downward flow, there are significant interactions occurring between slag and other phases, ie gas and packing particles. In particular, the interaction between gas and slag is closely associated with the key flow phenomena such as loading, flooding or channelling in the lower zone of the BF. With gas introduced laterally through tuyeres and slag flowing downward from the cohesive zone to the hearth, this interaction varies throughout the lower zone and in the cohesive zone:  strong cross-flow of gas relative to the slag occurs in front of the raceway  counter-current flow of gas and slag occurs in the upper parts of the lower zone  both strong cross- and counter-current flow of gas and slag around and within the cohesive zone. These interactions can be linked to furnace irregularities, affecting smooth operation and limiting production. Therefore, understanding the gas-slag interaction and its influencing factors remains critical for BF process control. In the current review, the physical behaviour and key influencing factors of gas and slag flow are initially examined. Numerical models describing gas and slag flows in a packed bed at micro-, mesoand macro-scopic levels, are reviewed. Each simulation approach has its advantages and limitations, as well as unique assumptions when used in BF process modelling. Applications of these approaches to gas-slag flow in key identified functional zones will highlight the differences between approaches and modelling outcomes. As no single approach can fully address all aspects of gasslag interactions, an integration of different approaches is considered an effective and beneficial method in providing a more complete understanding of gas-slag flow in the BF process.

Jun 19, 2024

By Chapman G. J

Mining operations require detailed and precise methods and procedures for the optimum selection of ore from waste. A fundamental procedure applied to achieve this selection is accurate sampling. The key parameter to accurate sampling is an understanding of the degree of heterogeneity of the key element contained within a sampling mass. This paper will describe the methods applied for the calculation of the fundamental sampling error and the techniques used to achieve a representative sample in the Fimiston Open Pit, Kalgoorlie.The utilisation of Pierre Gy's sampling theory has optimised the blast hole sample quality and quantity for submission to the assay laboratory. This has resulted in reduced cost and optimised assay reliability in statistical terms. Similarly the analysis of exploration drill holes for resource definition has optimised drilling procedures in terms of the drilling method, sample length and sample quantity.

Jan 1, 1993

By J Andrina, D Richards

The Grasberg is a large copper and gold open pit mine operated by PT Freeport Indonesia and located in the high equatorial mountains of Papua Province, Indonesia. The climate is alpine/sub-alpine with little seasonal variation in temperature and rainfall. The annual precipitation varies from about 3000 to 5000 mm over short distances around the Grasberg, but in general, an average daily precipitation of 10 mm per day applies and leaching of the overburden is continuous throughout the year. Mining commenced in 1988, and almost all of the overburden mined up to 2003 was potentially acid forming. The current acid drainage from this overburden is being collected and treated. From 2004 to the end of the Grasberg pit operation in 2014, approximately 70 per cent of the overburden will be potentially acid forming and 30 per cent limestone. A program of laboratory leach columns, field test pads and an instrumented full-scale dump was developed with the objective of defining scale up factors to quantify the acid and metal leaching rates and to evaluate the stockpile geochemistry and control options. The results of an ongoing seven year program have demonstrated feasible scale up between laboratory columns, field test pads and the trial dump in relation to material geochemistry and ARD evolution trends at Grasberg. The potentially acid forming waste types are highly reactive and maximum acid generation rate occurs within two to three years and that maximum copper release occurs within one to two years of exposure. The results also show that the net acid generation (NAG) test provides a good estimate for the potential acid load from overburden types. The chemistry, temperature and oxygen data from the trial dump suggest that oxidation and acid generation is occurring throughout the dump but at a decreasing mass rate with increasing distance from the toe of the dump. It is apparent that convection and/or advection are important mechanisms for the transport of oxygen into and within the dump. Key results and findings of the investigations carried out are presented and the implications of the findings for long-term ARD management at the Grasberg mine are outlined.

Jan 1, 2003

By A Bennett, A Peck

BHP has recently constructed a Hot Briquetted Iron Plant at Port Hedland in the Pilbara region of Western Australia. Supply of iron ore fines to the plant is by conveyor from the companyÆs existing Nelson Point stockyards. The conveyor passes under Port Hedland harbour in a concrete segmentally lined tunnel, approximately 1030 m long and with a 5.1 m external diameter. The tunnel was constructed by a Tunnel Boring Machine (TBM) which both excavated the ground and erected the tunnel lining. The tunnel was bored between cut and cover in situ concrete portal structures, the TBM being launched from the Finucane Island side towards Port Hedland town. The alignment required lengthy gradients of 1:6 on either side of the harbourÆs dredged channel, under which the tunnel is bored with a minimum clearance of 8 m.The tunnel is fitted-out with:1800 mm belt conveyor capable of 10 000 tph;walkway along which a specially designed inspection/ maintenance vehicle can run; andtunnel services including power, light, fire detection and suppression communications, water mains for wash down and sumps and pumps for drainage.This paper gives a general overview of the design and construct contract, important aspects of the design and the construction process itself.

Jan 1, 1999

By J Austin, R Bitencourt

Differences between the long-term model (LTM) and mine geology system (MGS) grade control block-outs on a blast block scale can impose difficulties to planning crusher feed grade and tonnes on a monthly to weekly blend basis. Detailed geological input to short-term planning has been integral to improve the performance and reduce risk in six-week to three-month production schedules and local variability in tonnage and grades is often not accurately represented in the LTM. The challenge of producing to combined target specifications from different mine sites in an integrated mine to ship business has been reduced with the creation of blast blockout-based short-term model. These short-term blast block models (STBBM or STM) are robust predictive tools created for upcoming benches of current mining areas by firstly collecting data from the pit in the form of bench and face mapping and projecting the structure and stratigraphy down to the next bench. A wire-frame of the projected contacts based on material destination from production blockouts is created and then checked against the LTM. Blast block data from the bench above including assay results and material logging is extracted and validated according to the projected wire-frames (geozones). Individual blast blocks and a full block model are created for each bench production defined by the STP (bench plans). Data output from the STM is in a compatible format for import into scheduling specific software packages. Additional information is incorporated into the STM to allow querying of drill penetration rates, predicted powder factors, material hardness and feed type to further aid in the production planning process and cost forecasting. To date, reconciliation of the STM has been pleasing and certainly an improvement on the LTM, especially in areas where variability is higher due to geological complexity. Short-term predictions derived from in-pit geological observations allow mine planners to more confidently decide on mining block sizes and schedule tonnages and grades, reducing the risk component attached to developing production schedules based directly upon long-term orebody models and mine plans.

Jan 1, 2005

By D Reid

Many of the relevant engineering behaviours of tailings are controlled to a large degree by the density of the material. For example, loose tailings are prone to brittle strength loss, while dense tailings are dilative (i.e. gain strength) at large shear strains. The critical state framework has been successfully developed over the past few decades to assess whether in situ conditions are contractive or dilative, and estimate relevant engineering parameters on that basis. Tailings comprising primarily silt-sized particles, when subaqueously deposited, often form a particularly loose state compared to subaerially deposited material of similar index properties. Such subaqueous deposition occurs in the decant pond area, where the tailings typically pluviate in quiescent conditions within a pond of standing water. Silt tailings deposited in such a manner have been observed to be extremely loose in a number of TSF investigations. Of particular concern, the deposited material in such cases appear to be significantly looser than can be reproduced in the laboratory - even using moist tamping, the sample preparation method which can usually produce the loosest samples possible in laboratory conditions. While the loose density of subaqueously deposited silt tailings is clear, in a well-managed upstream-raised TSF the decant pond is usually small and far from the perimeter embankments, however there are a number of examples where the engineering performance of such materials becomes relevant – for example, when historical deposition practices were poor, resulting in subaqueous deposition near the perimeter embankment. This paper outlines the geotechnical characterisation of a number of such subaqueously-deposited zones, compares the in situ state to that achievable in the laboratory, and discusses options for assessing the expected engineering performance of such materials when comparable laboratory tests are unavailable.

Jul 1, 2021

By D Thomas, B Gallagher

Valuable data for geotechnical interpretation and integration into effective Australian underground mine planning may often be available, yet is not always fully appreciated or utilised, particularly in the early stages of mine planning or in due diligence studies. There may be considerable benefits associated with early prioritisation of geotechnical evaluation and impact on mine planning. Unidentified, misinterpreted, or ill-defined adverse geological and related geotechnical resource characteristics can pose significant business risk to underground coal projects and operations. Preliminary resource definition in the early conceptual mine planning stages attributes significant focus (entirely warranted) on resource quality and structural geology constraints. Yet detailed geotechnical data analysis and interpretation, which may have a substantial down stream impact and sensitivity with respect to future mine planning strategies, at times is given lower priority, or scoped and resourced in the later stages of a bankable feasibility study. Through extensive mine planning experience and observation of downstream process impacts, it has been found there is often data available for geotechnical analysis that does not readily stand out or is not adequately understood or utilised, available at the early (conceptual) stages of mine planning. Part of the issue may be that exploration geologists are not necessarily experienced geotechnical engineers and do not necessarily recognise or understand all important parameters. Subject to appropriate application of experienced professionals data can be manipulated to provide key geotechnical hazard assessment at minimal cost, and provide a framework for understanding and optimising the mine planning process. Although there is no single prescribed strategy for resource evaluation from a geotechnical perspective, potential business risks and mitigation approaches can and should be adopted at the conceptual mine planning stage. There has been a recent focus in the metals industry to provide a reporting framework for geotechnical classification of mining projects. This paper outlines the strategies and gives examples of key analyses adopted in mine planning and discusses the relative merits of adopting a reporting framework as a tool for geotechnical classification in mine planning.

Jan 1, 2005

By H. J. Glass, A J. Cornah

Improving the quality of the variogram helps to improve subsequent estimation and simulation processes. Two strategies for conditioning data prior to construction of the variogram are investigated using data from the Luce iron ore deposit in Canada. One strategy is the classic approach in which the deposit is subdivided into a set of structural domains. The domains are analysed individually and datapairs are recombined to produce a variogram. The second strategy is reconstruction of the deposit at an earlier stage of its history through unfolding. This involves transformation of the Cartesian coordinates into stratigraphic coordinate system. Improvement in the variogram quality, expressed in a decreased weighted deviation from a fitted model, is observed for both types of data conditioning. This indicates that, for the Luce deposit, application of data conditioning could also help to inform the selection of sampling locations.

Jan 1, 2006

Future hard rock mining will gradually move towards complete mechanisation which lends itself to remote control and ultimately to robotic mining. This will require different technical inputs into mining engineering and one of these is in the area of rock'mechanics. Traditional hard rock mining has had little rock mechanics input. Problems arising from high stresses and poor ground conditions have in most cases be remedied after they occurred, in the worst case by abandoning a particular stope or area and starting elsewhere. In a fully mechanised remote or robotic mining situation the financial penalty for such an approach could be severe, as a major part of the production costs will be in the development and the equipment. It is therefore imperative that a complete rock mechanics feasibility study is undertaken before an area is set up for robot mining and that a continuous stability monitoring system is installed that will predict rock behaviour well in advance of mining, such that the necessary ground control measures can be implemented without impeding the continuity of mining. This system will utilise already existing instrumentation such as extensometers and stress cells, and possibly additional improved instrumentation which has to be developed for this particular Application.

Jan 1, 1986

By M J M Cunningham, M Greentree, J H Liu

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Palaeozoic rocks of north-eastern Laos are an attractive target for gold explorers due to the complex tectonic history and lack of past exploration in the region. Alluvial workings along the Nam Xiang River and its tributaries have highlighted the potential for gold mineralisation in the Vieng Kham region. The Nam Xiang River follows a regionally-extensive NNE-striking thrust fault. Adjacent to the Nam Xiang fault, the dip of the main foliation steepens, and in many places the stratigraphy is overturned as a result of this faulting.United Minerals and Mining Company conducted a regional exploration program to explore for gold. This included stream sediment and rock-chip sampling, and airborne geophysics. Geochemical anomalies were followed up with more detailed exploration, including geological mapping and soil sampling. Despite the relatively deep weathering profile, gold mineralisation is associated with a low-level but well-defined gold-in-soil anomaly. Drilling has shown that gold mineralisation occurs on structures and fabrics parallel to the main Nam Xiang fault. The highest gold grades are associated with brecciated sandstones that have experienced strong carbonate alteration. This suggests that late-stage structures such as the Nam Xiang fault are the major control on gold mineralisation in the region.CITATION:Greentree, M, Cunningham, M J M and Liu, J H, 2015. Gold mineralisation along the Nam Xiang fault, Vieng Kham Project, North-east Laos, in Proceedings PACRIM 2015 Congress, pp 177–182 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Marwick PL

As part of its operations Hamersley Iron operates a heavy medium Concentrator to upgrade low grade, unsaleable iron ore to produce saleable lump and fines products. Firstly, the attempts at delivering a blended feed in both chemical and physical characteristics are presented. Improvements in blending controls are shown to have given process performance improvements. Secondly, improvements to the feed preparation section are detailed. These alterations are providing a much cleaner feed to the subsequent processing stages.

Jan 1, 1987

This paper examines the various stages of development and design work which were necessary to develop the cemented rock fill system for copper mining at Mount Isa. The reason for a cemented sand fill development program together with details of the test work undertaken are briefly outlined. The testwork associated with the selection of a suitable local rock to supple- ment the cemented hydraulic fill is discussed, as is the method for underground placement and mixing of the graded rock with the cemented hydraulic fill. The design features of the final system which incorporates a graded rock handling system and a cemented hydraulic fill reticula- tion system is outlined.

Jan 1, 1973

Factors influencing Cost, systems available for transporting minerals, particularly on land, and methods used for comparing costs are reviewed. A case study presents comparative costs graphically for coal haulage, assumed in Queensland, by 31-6" gauge rail, belt conveyor, 120 ton road train, slurry pipeline, and transmission of electrical energy by transmission line. The effect on comparative results of alternative methods of including initial capital and capital replacement costs is considered and approximate break-even points between systems, bearing in mind the assumptions taken, are discussed.

Jan 1, 1973

Grade control aims to deliver quality tonnes to the mill via accurate definition of ore and waste. It comprises data collection and interpretation; local reserve estimation; supervision of development and mining; and stockpile management. The foundation of all grade control programs should be that of high quality sampling supported by geology. The requirement for quality grade control samples has long been recognised, where they should be representative, unbiased, safe and operationally timely. Underground sampling methods include chip and channel samples; grab samples; and drill-based samples. To achieve quality samples, collection techniques employed should minimise delimitation, extraction and preparation errors. Grade control staff should be well-trained and motivated, and mining staff should understand the need for grade control. This paper reviews grade control sampling methods and presents recommendations for best practice and minimisation of sampling errors.

Mar 1, 2010

A BRIEF account of the water-power potentialities of Tasmania is given, together with possible applications of the power commercially. A short history of the Waddamana development is then given, and the main works are described.WATER POWER POTENTIALITIESTasmania is an island of approximately 24,500 sq. miles area (exclusive of small islands). An area of 12,000 sq. miles is at an elevation of over 1000 ft. above sea-level, and of 2300 sq. miles at over 3000 ft. above sea-level. Average annual rainfall varies from' over 140 in. on West Coast to 20 in. on East Coast, and for the whole island averages 48.5 in. The total water-power available, based on conservative figures for run off and efficiency, is 6,000,000 b.h.p. Only a small percentage of this total will, under present conditions, and under likely conditions in the immediate future, be capable of being developed commercially.An extensive hydro-metric and water-power survey is at present being carried out in order to collect information concerning the most promising water-power schemes. Already 400,000 b.h.p. has been located in different proposals, and there is still a large area of very likely country along the West Coast which has not been investigated yet. Tasmania thus has very vast power potentialities, which, combined with good ports and communications and wonderful mineral and timber resources, should augur well for the establishment of the great key industries, particularly chemical and metallurgical.

Jan 1, 1923

By A W. Bewsher, T C. McCu, D B. Mapleson

The Miitel nickel sulfide deposit has been overprinted by a family of late stage structures that have acted as conduits for fluids that have contaminated the orebody with arsenic minerals. This has resulted in highly variable and unpredictable arsenic grades throughout the Miitel orebody. The ore produced from Miitel is processed under a toll-treatment agreement with Western Mining Resources Kambalda Nickel Concentrator. Part of this arrangement includes a financial penalty if monthly average arsenic grades in ore delivered exceed 800 ppm. This constraint has provided an extra challenge to the Miitel mine geologist in addition to daily underground duties. Routine development and stope mapping, close spaced sampling and cross-sectional interpretation were used in building an understanding of the structural controls of arsenic mineralisation and ore repetition at the Miitel nickel mine, and in providing maximum input to mine planning and scheduling. The distribution of structures responsible for arsenic introduction is now well understood from detailed mapping, sampling, and interpretation. By applying these insights to mine scheduling, the operation has successfully managed arsenic levels within the required specifications. Geological mapping has also improved the understanding of the structural complexity of the ore deposit, leading to the addition of ore tonnes and an increased confidence in resource modelling. Regular sampling and tight controls on data quality provided confidence in a strongly skewed arsenic data set. Multiple Indicator Kriging has been used for resource estimation of the arsenic contaminated nickel ore since it allows explicit control of the spatial influence of extreme grades in the positively skewed arsenic sample population. Both the grade control and exploration data sets are used to model the arsenic distribution.

Jan 1, 2003

By Wright S, Rogers L. J, Precious T. H

Brown coal and its char were investigated as substitutes for petroleum coke in the manufacture of anodes for Hall-Heroult cells. The char, which had been densified by several techniques, was made into compacts with various binders and the anodic consumption determined during electrolysis. The results were an improvement on previous work, but the anodes still fell short of acceptability for use in aluminium smelters because of intractable microporosity. Some options for future development have been discounted.

Jan 1, 1986

Based on twenty years of experiences of applying computers in mine water engineering in Hungary, a program package was developed for home utilization and for other users abroad as well. This program package has been adapted to the CAD System of Coal Mining of COMECON countries. The main features of the "mine water subsystem" in the CAD System of Coal Mining and short descriptions of the key programs of the package are presented in this paper. Foreword The serious water problems of Hungarian mining pressed and/or stimulated its professionals to apply computers for supporting their problem-solutions. The first trials of these computer applications in mine water engineering were dated from the sixties. Owing to its twenty years of experiences in computer appli- cations in mine water engineering the Central Institute for the Development of Mining in Hungary was requested to work out the "Subsystem of Mine Water" for the Computer Aided Design System ('CAD) of Coal Mines in COMECON countries. This paper gives a brief presentation on the main features of this "subsystem"with reference to significant components.

Jan 1, 1988

Mining is a high risk, high capital and potentially high reward undertaking. A large proportion of the risk comes from a lack of definition of the orebody (which also provides some of the potential) and the unpredictable nature of the market. This makes the planning process difficult but encourages the development of a robust yet flexible mining system. The system should be capable of absorbing some deviation from the anticipated concept without a significant impact on profitability. The mine planning process tends to consist of a series of related but discrete stages. For instance, the pit shells are designed, a schedule for the pit shells is created, a plant fleet is chosen to achieve the schedule and a financial analysis is carried out on that scenario. It is likely a few iterations are carried out using various mill throughputs to produce a favoured financial result. The problem is that handing results from stage æBÆ for use in æCÆ doesnÆt encourage a flexible system. æCÆ is likely to be built for exactly æBÆ. Unfortunately, in mining, æAÆ (the orebody) has the highest potential for variability and impacts everything else downstream. æDÆ the market also has high potential for unplanned variability. These variations can spread and æreverberateÆ through the whole mine process. For example an unexpected increase in ore oversize impacts all downstream mine processes to the primary crusher which may in turn create problems back æupstreamÆ by restricting throughput rate. Also an unexpected drop in demand or price could require modifications to the planned production rates. This paper looks at how mining process simulation can be used to support the development of strategies to counteract unforseen circumstances or alter production to match fluctuations in demand and price.

Jan 1, 2003

By H Zahiri

Utilisation of the InSAR technique for monitoring of subsidence in mining areas, employing open pit and underground mining methods, has large potential due to sensitivity and safety issues associated with usage of the classical surveying techniques. InSAR can also be very competitive concerning the cost of provided results. However, there are a few issues that may significantly limit InSAR applicability for subsidence monitoring in mining areas. The altered terrain topography, involving steep slopes and deep pits, may lead to the layover of radar signal for specific satellite and pit geometry. Also, the highly dynamic character of subsidence induced by mining, especially using mass mining methods, may lead to issues such as apparent heave and ambiguous results. In this paper the authors analyse the above-mentioned issues and demonstrate how InSAR technology was applied, as a supporting system, to monitor large scale and highly dynamic subsidence for a real case study in Western Australia.

Jan 1, 2008