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Mine planning studies of iron ore deposits are often based on resource models generated by ordinary kriging. Ordinary kriging aims for local accuracy to minimise the variance of expected estimation error but this is at the expense of reproducing variability of the original sampling data. Hence mine planning studies using kriged models are likely to underestimate product variability, and the required blending and stockpiling capacity to reduce variability to an acceptable level. Instead, conditional simulation models of the main chemical variables in iron ore are able to reproduce likely variability to be encountered during mining and processing. This approach is demonstrated in a case study of the Weld Range bedded iron ore deposit in Western Australia, with a comparison of ordinary kriging and conditional simulation models. Conditional simulation models suggest that, compared with the single ordinary kriging estimation, there is likely to be far greater block variability for iron and impurities, a greater requirement for stockpiling and blending capacity, highest variability in initial years of mining and less variability in later years of mining for deeper ore. The conditional simulations provide a more realistic range of mining outcomes for production of high-grade ore, which may be seven per cent less than in the kriged model, as well as for lower expected project net present value (NPV). In year one, the kriged model is conservative for NPV; however, in later years two to five the kriged model has higher NPV than most conditional simulations, suggesting expected NPV based on the kriged model may not be achieved. For improved decision-making in mine planning, a complete range of possible outcomes from conditional simulations of the deposit should be considered rather than relying on a single kriging estimation that may be an end member case in the range of possible mining outcomes.

Jan 1, 2009

By Weir D. R, Doyle B. N

The Sherritt Zinc Pressure Leaching Process is based upon the direct pressure leaching of zinc sulphide or lead-zinc bulk sulphide concentrates to produce zinc sulphate in solution and elemental sulphur in the leach residues. The zinc sulphate solution is compatible with conventional purification and electrowinning technology. The pressure leach residues can be treated for the recovery of elemental sulphur, lead and silver. With the conversion of sulphur to the elemental form, zinc pressure leaching allows zinc winning to be independent of sulphuric acid production. Direct pressure leaching of zinc sulphide concentrates was started commercially in October 1980. Continuing research and development studies have defined various pressure leaching configurations for integration with existing roast-leach operations, for grass roots plants, or for plants which are to have the roast-leach section completely replaced. These studies have included the treatment of zinc concentrates from various Australian producers and the development of process flowsheets for potential applications in Australia.

Jan 1, 1989

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

Jan 1, 1988

By Turco E, Pelizza S, Castellani F, Stanganelli V

Excavation are in progress for the building of tunnels of the waterworks in West Campania (Naples). The works afferent to part II envisage tunnelling through a miocenic clay formation over consolidated by two tunnels whose sections are respectively 50 and 10m2. Tunnel blasting is carried out by mechanical means. An excavator is used in the big tunnel, whereas in the small tunnel a roadheader machine is used for a short tract and a mechanized shield is used over a long stretch. The tunnel feature complex problems regarding stability. This is particularly so for the big tunnel whose face appears unstable. For this reason the clay on the face is sistematically bolted by means of 3-metre and 12-metre bolts. This prevent the use of a TBM for tunnel Excavation.

Jan 1, 1987

In order to realise seafloor massive sulfide (SMS) mining, the environmental baseline survey around targeted SMS mining areas and the creation of an environmental assessment technique suitable for quantifying the impacts of ocean floor mining are necessary. The targeted areas generally host large chemosynthetic communities in association with active hydrothermal venting. The ecosystem structure around the chemosynthetic communities has not been clarified yet in macro-scale or quantitatively. The systematic approach and plan for the baseline survey and the environmental assessmentÆs basic studies are introduced. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

A static equilibrium mathematical model of the lead,flotation circuit at The Zinc Corporation Limited is developed to permit the feasibility of applying computer control techniques to be studied. The model is based on the relationship between the cumulative recovery of a mineral species R from n flotation cells or assemblies in a unit given asR = M(1-(1 - p)?)where M is the maximum possible: recovery and p is the probability of flotation for the particular mineral.The verification of this relationship by data from pilot plant cell-to-cell and plant open flow flotation units shows that these systems behave as if the probability p is constant for each cell or assembly of anyone unit. It is also concluded from this study that mineral recovery is independent of the head assay. Two consequences of this probability relationship, are demonstrated.1. The total recovery from an open flow unit is enhanced by increasing the number of flotation assemblies but maintaining a constant flotation time and total air addition.2. The rougher and scavenger capacity required to recover a bulk lead-zinc concentrate is approximately half that used for selective flotation.The static equilibrium model is derived by solving a series, of mass balance equations which incorporate the recovery-probability relationship for each type of flotation unit. It is used to calculate the complete metallurgy of the circuit for any arrangement of cells knowing only the plant feed assays and the probabilities of flotation for the three mineral types, galena, marmatite, and gangue for rougher, scavenger, and cleaner flotation. The high degree of prediction obtained is demonstrated by comparison with plant results.Pulp flowrate is the principal variable affecting the accuracy of the present model. Work is in progress to establish this effect and permit the derivation of a dynamic model. Even so, the static model is valuable in its present form for the analysis and design of circuits, and optimisation studies using computer services have been conducted.

Jan 1, 1964

Groundwater issues for the mining industry are many and varied. When the depth of mining is below the water table/potentiometric surface, a groundwater æsinkÆ is created which alters the local groundwater flow regime resulting in minewater inflows. Assessment of mine dewatering, mine water balance and wastewater disposal requirements are central to the effective management of water in a mining operation. Each of these issues has a significant groundwater component. Other groundwater issues for mining operations include: water supply, aquifer storage and recovery, the impact on other groundwater users in respect of groundwater levels, bore yields and water quality, and the development of an effective groundwater monitoring network for early detection of impacts and to satisfy regulatory requirements. This paper outlines the techniques involved in assessing groundwater issues for project feasibility, during operation and post closure, and provides an overview of several mine dewatering and water disposal methods. The practical assessment of groundwater issues for the mining industry is illustrated with several case studies of mining projects in Australia, SE Asia and the subcontinent. These are projects to which the author has contributed during a career as a geologist/hydrogeologist spanning more than 25 years.

Jan 1, 2003

The purpose, basic data requirements and various analysis/modelling tools employed for geomechanical evaluation of mine-site conditions are overviewed. The impact and application of computer technology are dis- cussed. Broad guidelines and criteria are presented for establishment of a practical geomechanics data-base system to yield infor- mation suitable for mine design purposes. Future needs of the Australian mining in- dustry are examined.

Jan 1, 1983

There has been considerable attention in the literature to coarse sizing by wet and dry screening, but these methods have not proven to be applicable to the calculation of screen capacities for fine wet sizing, desliming and media recovery: A method is presented for the calculation of the size of screens for such duties, being based on the mean particle size of the oversize material on the screen which reflects the surface area from which the fines or media must be removed. Similarly for dewatering, it is the area from which the water must be drained. Desliming, media recovery and dewatering are each considered along with water require- ments both with the feed and as wash water.

Jan 1, 1984

By L Soares, W T. Hennies, F Fujimura

The engineering geological mapping of Metropolitan Area of Jopo Pessoa in the littoral zone of the Parafba State, northeast of Brazil, made possible the ambient characterisation for space using and its implications on the environmental resources. This region comes lately denoting an accented industrial growth and this work would help future projects of urban planning, distinguished by quick ground occupations for residential, industrial installations, farming, beyond mineral extractions. The mineral sector supplies material and substance demanded by industry and civil constructions, like as clay deposits, sands, calcareous rocks and mineral water. Many companies working there do not have the permission or inspection of ambient agencies for planned extractions of mineral resources. The consequences of this activity pass for the low profit of the reserves, bad uses of the sources, ground degradation, vegetation suppressions and physical impacts on landscapes, beyond noises and vibrations. These activities have causing accelerated alterations and transformations in the environment, compromising the sustainable development. It thus becomes clear that urgent solutions must be find to solve the problems with human interferences by closer inspection and management for disciplined use of its natural resources.

Jan 1, 2003

Launching the Queensland Water Plan 2005 - 2010 in August 2005, Premier Peter Beattie compared the stateÆs water resources with liquid gold. QueenslandÆs peak industry body for the minerals and energy sector, the Queensland Resources Council (QRC), believes the analogy is appropriate. During early development of an industry water strategy, it has become apparent that water is like liquid gold, in that it is revered, hoarded, recycled, priced on purity, a magnet for speculators, both difficult and expensive to transport effectively, heavily regulated and fundamentally linked to issues of security. To date it has generally been economic and relatively straightforward for the resources sector to secure water. Although production has not been compromised, this must not be grounds for complacency as there is every indication that water will continue to become increasingly expensive, more tightly regulated and, relative to a growing demand for a finite water supply, increasingly scarce. During 2006, QRC has developed and is implementing a voluntary industry water strategy to address a range of challenges confronting the resource sectorÆs security of access to water. As a consequence of, at times, protracted community consultations over QueenslandÆs catchment-based water planning processes it has become clear that many community stakeholders have outdated perceptions of the stateÆs resources sector. Once established, QRCÆs water strategy will incorporate a community engagement campaign to present the industryÆs credentials as a leader in water resource management. The development of QRCÆs water strategy, and the challenges the strategy is designed to address, provides insight into the fundamental reforms that are occurring in how water is managed and regulated in Queensland. These reforms have implications for how government policies are designed and administered and also for how industry engages with communities during this transition process.

Jan 1, 2006

By A Havenga, F, J Hough, R Grobbelaar

After the closure of mines they naturally start to fill up with water. As a result, hydraulic gradients develop between adjacent mines and different hydraulic water pressures are exerted onto peripheral areas or compartments within mines. This results in water flow between mines, or onto the surface. This flow is referred to as intermine flow. The geometry of the collieries in the central Witbank Coalfield make intermine flow possible in several areas. Since the Department of Water Affairs and Forestry declared intermine flow as one of its greatest concerns for granting closure to South African mines, much research into this phenomenon has been undertaken. The importance of the quantification lies in the DepartmentÆs goal of sustainable water management, and the possible long-term financial implications these flows could have for individual mines. The challenges of determining intermine flow are numerous, and attention is focused on the identification of areas where these flows can take place. Detailed mining plans on a regional scale are required, and detailed coal-seam floor data are combined to provide targets for possible interaction between these mines. The quantification of these flows is problematic due to the uncertainties regarding geometrical configurations and the variation in site-specific hydraulic characteristics of the coal and overlying lithilogical layers. To this end, use has been made of several analytic solutions and numerical flow modelling. Stage curves (volume versus elevation curves) for the opencast and underground workings have been calculated and first-order estimates for intermine flow or decant from these areas have been determined. The numerical modelling methodology entailed a down-scaling approach, starting with a broad regional model covering the entire area, followed by modelling the interactions between interconnected mines and finally looking in detail at the major areas of interaction. By considering different scenarios within the context of these flows, possible management options for intermine flow can be evaluated in terms of volumes and qualities that might emanate in the post-closure phases. Challenges for the future include obtaining site-specific information on the groundwater hydraulics and acceptable ranges for model parameters, and verifying model results over time.

Jan 1, 2003

The strategy of adjusting operating conditions to maintain optimum process performance as the feed quality varies - adaptive optimisation - is being investigated by computer simulation of chemical processes for the treatment of ores. Those ore-process systems that are most likely to yield substantial benefits from adaptive optimisation are being identified as a guide to the selection and development of systems for practical application. The generalised mathematical representation of the cost structure, ore quality variations, process kinetics, reactor characteristics and operating variables for ore-process systems is described. Results are summarised for temperature, reagent concentration or residence time as the manipulated variable. For almost all systems, adaptive optimisation was economically beneficial, although a few exceptions have been identified where there is a significant synergistic effect between poor-performance and good-performance materials in a blended feed. The sensitivity of the benefits of adaptive optimisation to a range of economic and technical factors is summarised.

Jan 1, 1985

During the last 20 years, manufacturers of Australian iron have given increasing attention to development of external markets for processed blast furnace slag. Slag has been in widespread use overseas and data on the performance of Australian slag in concrete lave shown it is suitable for that use. Chemical and physical properties of typical Australian slag products including air cooled, granulated and pelletised slag are discussed and compared with local natural aggregates. Special attention is given to pumping achieve- ments with slag concretes and the observed durability of concrete after many years service. More'recent applications for granulated slag as a sand replacement are discussed. It is concluded that'whilst more wide- spread use of slag is possible, the cost of marketing and transporting slag are likely to restrict opportunities unless for local usage.

Jan 1, 1979

By E Villaescusa

This paper describes a methodology for the design of mine pillars at the McArthur River Mine. The pillar strength is calculated using a method that accounts for confinement, pillar geometry and intact rock properties. The average pillar stress was calculated using in situ measurements of vertical stresses at shallow depth and the tributary area method in conjunction with numerical modelling. Observations of pillar behaviour indicate that an existing pillar stability graph may be slightly conservative and further adjustments for the local rockmass conditions are needed. The results to-date indicate that all mine pillars are stable for a range of mining geometries at McArthur River Mine.

Jan 1, 1998

By S R. Hencher

The development and availability of modern software for cavern design over recent years has provided design engineers with a range of usable design tools. The paper discusses the range of modern software available, presents a design methodology, reviews ground investigation requirements and software available for data processing and management, and discusses requirements and common analytical considerations with reference to typical packages. Caution is given of the tendency for readily available and user friendly software to be used without a full appreciation of the underlying engineering principles.

Jan 1, 1999

o Resource production is essential for society. o Demand for resources will increase as population grows.o Resource industries are the main consumer of trained geologists.o The lead time from(1) training to productivity(2) research to resource production is measured in years.o An adequate supply of well trained geologists and successful geological research is an important agent in ensuring cost effective, adequate supply of mineral resources for society. Therefore the main beneficiary of geological education is society itself.o Society is paradoxically apathetic or antagonistic to the resource industry because (1) it represents change(2) lobby groups working for other causes have successfully moulded a bogey man image for the resource industry in the public eye.Professional training and research for resource industries consequently lack popular support. Funding is at an absurdly low level in comparison with the economic importance of resource supply.

Jan 1, 1990

By Robinson WB

An accurate and rapid assessment of coal resources, such as that provided by computer modelling, forms an intergral role in evaluating CSR's coal deposits for future development. An in-house system utilising a number of geological, engineering, costing and financial evaluation routines has been developed for DEC VAX computers. The system is currently being upgraded and enhanced to meet the demands at the various mine sites. Computer modelling of the geology is performed on encoded drillhole information and coal core chemical and physical analyses. A conceptual mine plan is formulated then digitized and superimposed on the geological model. Insitu and product coal reserves and qualities as well as overburden and parting quantities are then calculated for each strip or block. These strip parameters are then transferred to the mine scheduling routines to determine the most efficient mining sequence for the mine plan. Cost factors and scheduling data for equipment specified in the conceptual mine plan are used in the mine costing subsystem. The financial subsystem then evaluates the likely return on investment. Future enhancements to the system include improvements in the response time through the introduction of interactive graphics, the direct interfacing of geophysical and analytical data, and further development of a geotechnical'database.

Jan 1, 1983

In preparation of this Paper, the emphasis has been laid on the commercial rather than on the technical and scientific aspects of coal evaluation. It is intended to describe and comment on the principal factors which currently determine the selection and procurement of coking coal for the steel industry, and is not based on the results of any original research by the author. Evaluation of different coals for strictly thermal uses, for gas production or other chemical applications has not been attempted, and comparisons of coal with other fuels have been excluded: the paper is concerned only with coals for the production of blast furnace coke. The discussion is strongly related to, and illustrated by, British, and to some extent, other Western European practice, but it is hoped that the general conclusions may have a wider application.

Jan 1, 1975

Stressed steel cables, similar to those used in pre-stressed concrete, have been used for rock mass reinforcement, in civil engineering, for many years. This type of reinforcement has been attempted for open pit wall support, on several occasions, but has never gained wide acceptance as a practical approach because of high cost and complexity of installation in a mining environment. On the other hand, untensioned, fully grouted cable dowels (cable bolts) have gained wide acceptance for ground support in underground mining and it is perhaps surprising that this technique has not been used to a greater degree in open pit mining. The first systematic application of this technique in Australia was at the Mary Kathleen uranium mine in 1976, where it was spectacularly successful in maintaining steep stable walls in a jointed rock mass with unfavourably dipping structures. Cable bolting, and other techniques, are now being used to an increasing degree for wall support in both small and large open pits, for two basic applications: 1. stabilisation of potentially unstable sections of a wall, or 2. to allow steeper walls and reduce waste stripping volumes. In virtually every situation, wall rein- forcement has significant economic as well as technical advantages. The paper describes the development of the techniques, the mechanisms of wall support, the methods used, and discusses several case histories of its application to Australian open pit mines.

Jan 1, 1986