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By Cowie WJ, Utting BS

The alluvial gold industry of New Zealand is based on the placer deposits in Otago and on the West Coast. Production from these since discovery in the 1850's has been an estimated 480 tonnes (15 million ounces) of gold. Annual output has expanded continuously since 1980 and is expected to be over 2 tonne of gold for 1989.Following a historical review, the characteristics of typical operations, which use hydraulic excavators and mobile trommel units are discussed. Descriptions are then given of alluvial activities in Otago and on the West Coast.

Jan 1, 1990

Better quality at lower cost is today's formula for remaining competitive in a world market. For an integrated steel company, high quality low cost steel production must originate before the blast furnace. In 1979, when U.S. Steel initiated a Quality Management Program throughout its steelmaking operations, efforts began at the coal, ore and flux mines. The objective was to improve the quality and reduce the variability of the critical parameters for steelmaking raw materials, to get the blast furnaces, and subsequently the melt shops, under optimum control. The general details of U.S. Steel's Quality Management Program are discussed and how it was used to promote the desired improvements in steelmaking raw materials. Some of the outstanding results obtained by the cooperative efforts between the mines and the steel plants are reported. The lessons learned by U.S. Steel were through upgrading existing operations and facilities. These principles should now be applied to new projects and the benefits of good quality management should commence from the time new projects are Commissioned.

Jan 1, 1986

By E Jak

A viscosity model has been developed for both completely liquid and heterogeneous, partly crystallised slags in the Al2O3-CaO-æFeOÆ-SiO2 system in equilibrium with metallic iron. The Urbain formalism has been modified to describe the viscosities of the liquid slag phase over the complete range of compositions and a wide range of temperatures. The Roscoe equation has been used to describe the effect of presence of solid suspension (slurry effect) on the viscosity. The parameters of the viscosity model were optimised to describe large experimental data set in the low-order subsystems, as well as in the multi-component system. The computer package FACT was used for prediction of the proportion of solids and the composition of the remaining liquid phase. The model provides a good description of the experimental data (over four thousand experimental points) in liquid phase, and liquid + solid mixtures, over the complete range of compositions and a wide range of temperatures. This model can now be used for viscosity predictions in industrial slag systems. An example of the application of the new model to slag cleaning and reduction smelting processes is given in this paper.

Jan 1, 2000

By P Commander

Western Australia is a major exporter of minerals, which places significant economic and environmental responsibility on Government and the stateÆs mining industry. Moving into the 21st century, mineral production in Western Australia is $14 billion accounting for 50 per cent of the stateÆs export income. There are over 60 large-scale mining operations distributed throughout the arid regions of the state (less than 300 mm/year rainfall). There are four key mineral provinces in arid Western Australia including the Pilbara (iron ore), Murchison (gold), Northern and Southern Goldfields (gold and nickel). These provinces have significant differences, particularly in respect to groundwater demand from mining and mineral processing, aquifer systems that are utilised, and approaches to groundwater management. The arid nature of the stateÆs interior and subsequent lack of surface water resources has required substantial groundwater resource development by the mining industry. A variety of aquifers have been explored and utilised ranging from shallow alluvium and calcrete, discrete fractured zones in bedrock, concealed palaeochannels and inland sedimentary basins. Groundwater usage by the mining industry is about 150 GL/year with most abstraction related to mine dewatering, mineral processing and dust suppression. Groundwater abstraction in Western Australia is regulated by the Water and Rivers Commission. In the Goldfields, the depletion of brackish (>2000 mg/L) and saline groundwater from storage is permissible, as mining is considered the beneficial use for groundwater which may be as much as 200 000 mg/L. In contrast, the low salinity groundwater of the Murchison and Pilbara is allocated on a sustainable basis. The role of monitoring and ongoing aquifer reassessment is crucial in water management, in evaluating the condition and performance of stressed aquifer systems. Mining operations face a variety of water resource issues ranging from insufficient availability for processing to excessive mine dewatering. These issues also change as a mine operation proceeds through its development, commonly starting with a deficiency and moving into surplus as deeper pits require more dewatering. Operating mines have to contend with three main issues: water supply, wastewater disposal and contamination of local water resources. In contrast, post closure issues are related to aquifer recovery or re-establishment of groundwater equilibrium, development of pit lakes in mine voids and isolation of waste products and associated seepage or run-off.

Jan 1, 2003

To carry out its responsibilities the SECV needs to manage the visual environment effectively. Every land oriented decision effects what we see and the value in pursuing visual excellence is supported by informed opinion, widespread community interest and evidence of cost- effectiveness.By knowing how we perceive the landscape and then changing or conserving it we can assist in fostering a positive mental image of a countyside which is welcomed by the local and regional community.It is useful to examine key design elements and the value we place on visual impressions in relation to three significant SECV rehabilitation projects, at Loy Yang, Newport and Morwell Open Cut.

Jan 1, 1992

By Pollmans GJ, Hoberg H, Schneider FU

The Institute of Mineral Processing at Aachen University of Technology has been engaged in fine and ultrafine comminution for several years. Former investigations had been dealing with the mechanical activation with the aim of increasing the solubility of highly resistant oxides such as tantalite and niobite while research on the product of ultrafine powders is of major importance at the moment. Materials of that kind are of increasing interest in the production of extremely resistant ceramics, in the development of new raw materials, in powder metallurgy and in the production of fillers (extender pigments) and pigments. The creation of ultrafine powders is difficult and very expensive. They can be produced by means of condensation or dispersion methods. One important method of dispersion is mechanical comminution. Due to long and intensive research and development all over the world important advances have been achieved but still a great number of questions and problems occur especially in producing materials of submicron and nanometer grain sizes which could be answered or solved only insufficiently up to now. These mentioned difficulties refer especially to: ò the required energy input into the feed material, ò the forming of strong agglomerates and wall stickings, ò the required product qualities, and ò the entire and reliable characterisation of the products. Basic investigation aim to clarify the micro and macro processes of ultrafine grinding and work towards solutions to the difficulties mentioned above. The aim of the Institute's research is the development of a new grinding device for producing ultrafine powders. First results of a laboratory scale mill of that type will be presented in this paper.

Jan 1, 1993

By Murray G

This paper outlines the processes involved in acid generation from sulphides and the key factors in identifying and predicting time dependent changes in the nature of acid mine drainage (AMD). The initial characteristics of mine water; whether drainage from exposed mining faces, runoff and seepage from waste dumps or seepage from process tailings; do not necessarily reflect the long term potential for AMD. The ultimate quality of mine drainage is a function of the interaction of many chemical, physical, biological and engineering (operational) factors. Techniques are available that can predict the qualitative nature of acid generation and mine drainage quality but accurate quantitative predictions are essentially impossible at the present time. As more and more mining operations exploit sulphide ore, the AMD and acid waste issue will become a. far greater concern. The significance of time dependent factors in the production of acid mine drainage-.is not just restricted to particuL.ar mine sites but needs to be recognised by the mining industry as a whole.

Jan 1, 1988

By Finlayson J. F

The advantages of rapid and accurate analyses are becoming appreciated in many industries today and have resulted in a great increase in the number of samples received by their laboratories. This has caused some firms to consider the installation of one or more of the instruments available for analytical chemistry. In this country there are relatively few people with experience of instrumental methods and it is difficult for a firm considering the installation of such equipment to assess the advantages which instruments may give them, and to decide which instruments, if any, will be of most use to them. The object of this paper is to give a brief survey of instrumental methods in the field of inorganic analysis. Instrumental methods of analysis have numerous advantages when used correctly. They enable extremely rapid analyses to be made in many cases, e.g., analysis of refined lead by purely chemical means takes about two days whereas spectographically the analysis can be completed in approximately one and a half hours. The accuracy ofinstrumental methods, generally between 1 and 5%, is higher than most chemical methods for small percentages of impurities. Furthermore, if the instrument can be calibrated against absolute standards the errors are usually random and not biased to one side of the correct result. The sensitivity is high, enabling in many cases the detection and determination of smaller percentages than can be detected chemically. This high sensitivity enables and, in some cases, requires the use of very small samples, and results in considerable savings in reagents, allowing the analysis of considerably more samples without undue loss...

Jan 1, 1951

By Channon W, Dube M, Makwana M, Kerfoot D. G

In early-1995, the Bindura Nickel Corporation commissioned a pressure leach plant at its Smelter and Refinery complex located in Bindura, Zimbabwe. The novel pressure leach process was developed by Sherritt to treat the nickel-copper sulphide residue produced from the original atmospheric leach circuit. The process extracts essentially all the nickel from the nickel-copper sulphide residue under non-oxidising acid pressure leach conditions, thereby producing an upgraded copper sulphide residue suitable for smelting and refining to electrolytic copper. The commissioning of the pressure leach plant was relatively smooth and design conditions were achieved within six weeks of operation. This paper presents a brief description of the process development and the plant design, followed by highlights of the plant start-up activities and summary of the plant performance.

Jan 1, 1996

By M Wortley, O Gu, D La Rosa, J McMaster

Metso Minerals Cisa have developed VisiofrothÖ û a system which calculates parameters of the froth surface using vision from remote cameras mounted about individual flotation cells. The parameters calculated from this system can be utilised within process control strategies to achieve stabilisation or optimisation of the flotation process. As part of a JKMRC AMIRA P9 field campaign, froth vision was collected from various cells operated at different air rates and froth depths within Rio TintoÆs Northparkes copper roughing and scavenging circuit. At the same time, samples were collected to determine the cell metallurgical performance at each operating condition. These froth images have been processed using the VisiofrothÖ system with froth velocity, bubble size, froth collapse rate and various froth colour parameters calculated. These parameters have been compared to the measured concentrate flow and concentrate grade produced at each condition. This analysis shows that the concentrate tonnage flow is strongly correlated with froth velocity whereas the concentrate grade is best correlated using froth velocity in combination with a bubble stability parameter which affects the bubble size distribution on the top surface of the froth. This paper summarises the results from this analysis as well as an overview of the VisiofrothÖ system and the parameters that are measured by the software.

Jan 1, 2007

By Wills BA, Barley RW

A brief description of viscosity measuring devices used in Dense Media Separation (DMS) plants is given, including a new On-line viscometer system. The various factors which affect suspension viscosity are identified. The effect of temperature variation on viscosity and viscosity measurement is examined in detail. Practical problems in using a modified Stormer viscometer for laboratory testwork are noted. Likely problems of continuous viscosity measurements are also discussed.

Jan 1, 1987

By R Uken G P Whitmore

The coastal dune cordon of northern KwaZulu-Natal is amongst the highest in the world reaching heights in excess of 180 m and up to 2 km in width. It comprises a complex system of Quaternary stacked dunes of various geomorphologies, types and ages. The dunes contain economic heavy minerals which are currently exploited ~20 km north of Richards Bay. Although mining of these ore sands has been in operation for the last two decades, little work has been undertken on the clay-fraction (

Jan 1, 2001

By P Ireland, S Mitra, G Evans, A Wang, M M. Hoque

This work presents an experimental study of flow dynamics in a bubble column system (crosssection: 100 mm × 100 mm) using a non-intrusive optical technique with targeted application in a novel REFLUX™ Flotation Cell. The study had two aims – measurement of the bubble size distribution (BSD) and local energy dissipation rate in the system due to bubble motions over a low range of gas flux varied from 0.02 to 0.08 cm/s without impairing the visibility of the system. A central bubble plume was generated by injecting compressed air through a sintered glass distributor in quiescent liquid. Highspeed shadowgraphy imaging was performed to determine the BSD in the presence of surfactant (Sodium Dodecyl Sulfate (SDS) concentration ~ 10 ppm). The BSD exhibited a unimodal shape at different locations of the column for all gas flux cases. A non-intrusive particle image velocimetry (PIV) technique was used to quantify the flow field generated by the bubble motions, which was used to estimate the local energy dissipation rate. The local energy dissipation rate exhibited an increasing power-law dependency on the gas flux.

Aug 24, 2022

Reconciliation of the ore reserve has been an integral part of mine planning since Bougainville Copper Ltd. commenced mining operations at Panguna in 1972. Confidence in the ore reserve is considered essential, both for long term planning of the deposit, and for fair and accurate reporting of the mining resource to shareholders. Recoverable, proven reserves are published annually. Although the ore reserve quoted is based only on diamond drill hole (DDH) information on a 122 metre by 122 metre grid, predictions are regularly reviewed against production. Concentrator results are taken to be the best estimate of grade and tonnage. Surveyed mined perimeters and average blasthole grades are reconciled at the end of each month against the concentrator figures. Predictions of the in-pit reserve are made using an orebody model. DDH and blasthole (BH) sample grades are used to make predictions for both long and short term planning. This paper describes how reconciliations are used to validate ore reserves at Panguna. Development of the orebody model is described, and some of the difficulties encountered in doing reconciliations are addressed.

Jan 1, 1987

By J B. Holman, P A. Weber, P Lindsay

Underground and opencast coal mining has occurred since 1896 on the Stockton Plateau, West Coast, New Zealand. Acid Rock Drainage (ARD) from historic and current mine workings has had an adverse environmental impact on the surrounding aquatic environment. The two main catchments affected by ARD from historic and current mine workings are the Mangatini and St Patrick Stream catchments. Solid Energy New Zealand Ltd (SENZ) is using active (e.g. alkali dosing) and passive (e.g. engineered cover) technologies to mitigate the adverse environmental effects associated with ARD contaminated waterways. This paper discusses the passive technologies. Principal strategies include the capping of high capacity potentially acid-forming volumes of overburden. The mudstones were found to generally have the highest sulphur levels compared to other overburden lithologies. Areas with high mudstone volumes are prioritised to be encapsulated and 390 Ha is planned to be capped in the Mangatini catchment in the near future.   Monitoring beneath granite, cement kiln dust and coal combustion product covers show oxygen can be reduced to less than 10% of atmospheric levels. Laboratory column leach tests that were subjected to oxygen flux rates of 10 % showed reducing oxygen ingress into acid-forming material can result in significant acid load reductions.   The oxygen content below the cement kiln dust cover was generally lower than 5% and water quality measured in lysimeters beneath this cover improved after 50 weeks of emplacement. Column leach tests containing saturated samples were undertaken to determine the most appropriate water medium in preventing pyrite oxidation. The sample saturated with ARD (pH ~ 3) had a negligible acid production rate and leached very minor Al concentrations although Al is soluble at low pH. This indicated saturating waste rock dumps with ARD can be an effective method in mitigating ARD formation.

Jan 1, 2007

By M Grinceri

The New MetroRail City Project was completed in 2007 in Perth, Western Australia. The project included construction of two underground stations, twin bored rail tunnels of 1.4 km combined length and cut-and- cover tunnels and dive structures of about 1 km total length. It is the first major underground construction project within the Perth central business district (CBD). This paper provides an introduction to the project and describes the geology and hydrogeology of the area. Ground conditions varied significantly along the alignment from soft estuarine muds in an area of reclamation to very dense cemented sands and very stiff to hard clays. Deep foundations for the project extend down into the bedrock below the CBD, a Tertiary siltstone/sandstone. Key geotechnical hazards encountered during the project are discussed. The building protection methodology on the project is described, including damage assessment, condition surveys, monitoring and protection of key structures.

Jan 1, 2008

The production of 100,000 tonnes per year of synthetic rutile from the processing of ilmenite, coal and copperas (iron sulphate) produces 200 cubic metres per hour of effluent water. A 2.0 hectare biological filter, comprising natural and man- made wetlands, has been built into the last stage of the effluent water treatment system. It is an area of shallow water (

Jan 1, 1988

By M Suzuki

Although several models for the surface tension of molten oxide slag have been proposed, suitably accurate predictions of this property are not yet possible. The surface tension, or surface excess free energy, of molten oxides is largely determined by the ionic coordination induced by surface relaxation. However, the associated mechanism of surface structural relaxation for molten oxide mixtures such as slag is complex and not yet fully understood. To allow a better evaluation of surface relaxation characteristics, the present work analysed the ionic coordination associated with the surface-relaxed states of several oxide mixtures. This work especially focused on calcium aluminate slags because these materials exhibit complex relationships between composition and surface tension. The effects of incorporating low concentrations of SiO2 as a surface active component on the surface ionic coordination were also examined. X-ray absorption techniques were used to assess oxygen and cationic elements in glassy samples after surface relaxation treatments, and molecular dynamics simulations based on a polarisable ion model of molten slag with vacuum/melt interfaces were also performed. The X-ray absorption techniques provided data related to electron yields (which are primarily associated with surface features) and fluorescence yields (which evaluate the bulk material). Thus, the ionic coordination characteristics of both regions were investigated. The results of molecular dynamics calculations allowed statistical analysis of the distributions of Al- or Sicentred polymorphs as well as the bond angles between cations and oxygen anions in the vacuumexposed and bulk regions in the equilibrated melt. The results indicated that bridging oxygen ions were preferentially distributed in the relaxed surface region rather than non-bridging oxygens. These bridging oxygen ions represented vertex connections between AlO4 or SiO4 tetrahedra. In the case of the calcium aluminate slags, the addition of one Ca2+ ion as charge compensation for two Al3+ ions was found to be necessary to form two AlO4 tetrahedra. This specific feature of surface ionic coordination could be responsible for the complex trends observed in surface tension data. The incorporation of low concentrations of SiO2 reduced the proportion of tetrahedrally-coordinated Al ions such that higher coordination states become dominant in the bulk of the material, whereas AlO4 tetrahedra were preferentially distributed in the surface region. SiO4 tetrahedra were the preferred Si-centred polymorph and were likely connected to one another to form bridging oxygen ions at the surface. On the basis of these results, a model to predict slag surface tension was proposed, and the energy of the formation of the ionic clusters resulting from surface relaxation was taken into account.

Aug 21, 2024

Over the past 15 years, Artificial Intelligence (AI) techniques have shown promise of providing the ability to capture `human intelligence' into a computer program. The sub-fields of Expert Systems and Artificial Neural Networks are finding increased use in industry to perform tasks previously considered the domain of human thinking. But, are these methods just a new type of software much like that of the past or is real magic hidden within the lines of code? Will this field continue to enjoy high growth rates and if so, what developments will we see in the near future? Which algorithms and methodologies will continue to grow? This paper discusses a number of paradigms which can be used to create successful applications. There are certain barriers; some psychological - some linked with knowledge acquisition, that must be overcome or avoided to ensure system performance. Development time also requires careful consideration before embarking on an Al project. The paper focusses on constructing goal-driven systems that transfer high-technology solutions from the research laboratory to the plant floor. Respect for system users is of paramount importance - whether their involvement is to access contained information or to participate in program maintenance as new knowledge becomes available. Examples of successful and unsuccessful AI implementation in Canadian industry and academia provide evidence of the importance of this issue. The paper also examines some current constraints on applying AI in the real-world. Among these problems are automated knowledge acquisition, methods to acquire data during run-time, real-time systems (hardware versus software), explanation and justification features and adaptive/leaning systems.

Jan 1, 1995

By Frazer E. J, Lwin T

Measurements of coulombic efficiency (QE) for zinc electrodeposition were carried out under mass-transfer-controlled conditions using a rotating disc electrode in synthetic acidic zinc sulphate solutions. Various methods of solution preparation and purifi- cation were investigated using reagents vary- ing from analytical grade to high purity; the purest solution was obtained-by dissolving 99.9999% zinc (Koch-Light) in sulphuric acid solution (BDH Aristar). Improvements in sol- ution purity did not necessarily increase QE, especially where apparently beneficial impur- ities (e.g., Pb) were initially present. The maximum QE obtainable through variation of temperature (T), current density-(i) and elec- trode rotation rate was established using a statistical optimization technique. The QE was determined principally by T and i, with significant interaction between these factors in the highest purity solution. QE contours, which gave an overall view of solution per- formance, were constructed and predictions about the response under conditions similar to plant practice were made. Wark's Rule (the dependence of QE on zinc/acid ratio) was obeyed in the purest solution over the range of composition commonly encountered in zinc plants. High concentrations of Na2SO4 and K2SO4, which occur in some plant solutions, were found to increase QE marginally ("1.2%). The intrinsic effects of individual impurities such as Cu and Ni were evaluated by additions (up to 5 ppm) to the purest solution. Decreases in QE were found to be minimal at the impurity levels normally encountered in zinc plants.

Jan 1, 1987