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By S Planeta

The use of explosives in underground mining has its drawbacks, particularly in the case of thin or narrow vein type deposits. Due to that, there is a need to develop more discriminative and safe rock-breaking technologies. Mechanical rock splitting seems to be one of the most promising avenues in this respect. This paper describes briefly principles and features of radial-axial splitters. It reviews a feasibility study done to evaluate a potential of this technology in selective mining. It was intended to compare productivity and cost of ædrill-splitÆ mining with conventional cut-and-fill method. Hypotheses and assumptions adopted, methodology used and the obtained results are presented and discussed. The study has confirmed an interesting potential of radial-axial splitters in mining thin and narrow vein deposits. In conclusion, it is stressed however, that it will take more R&D work to corroborate the results obtained. Some suggestions concerning future research in this field are also given.

Jan 1, 2003

Gold Fields Ghana Ltd (GF Ghana) currently operates an underground mine at Tarkwa, in south--west Ghana. The mine was operated by Tarkwa Goldfields Limited, a wholly owned subsidiary of the State Gold Mining Corporation of Ghana (SGMC). The mine was making operating losses and in a poor state of repair. Tarkwa Goldfields retrenched all the staff and GF Ghana assumed management responsibility for its own account on I July 1993.

Jan 1, 1997

By Wagland D. G, Guo H

The Mt Whaleback orebody is in a complex geological regime. A good understanding of geological structure is essential during the design and implementation stages. The amount of information on the rock-mass condition available at the design stage is considerably limited. It is essential to validate the rock-mass properties used in the design during implementation. It is important to achieve integrity of the final pit wall during development and to maintain the integrity until the end of its designed life for safe and economical extraction of ore. The original geological model is updated by way of on-going detailed geological face mapping. Original design is reassessed and is modified based on any significant variations to the previously evaluated geotechnical conditions. Information gathered during design implementation provide tools for effective management of the pit walls. Controlled blasting techniques are employed in the final limits blasting. Presplit blasting is used in most limits blasts. Presplit helps to maintain the integrity of the wall by venting excessive gases from the limits blast. This helps to reduce bedding dilation by gas penetration. Also, it helps to define the design batter for the operators for final batter trimming. Pyritic shale needs special attention during blasting due to its reacting nature. Cablebolting is applied in selective areas to secure small-scale potential instabilities. During the development phase, pit wall monitoring instruments are installed. These instruments are used to monitor the performance of the wall during and after excavation of the slope.

Jan 1, 1995

By G Giles

One of the main tools used by mining operations to mitigate the risk of rock burst is the installation of a so-called ædynamic resistantÆ support system. Such systems are designed to absorb the impact of shockwaves created by mine-induced seismic events. Dynamic support must be strong and capable of sustaining high loads and, at the same time, they have to be flexible and accommodate large deformation. A dynamic support system is therefore a system capable of absorbing a high quantity of energy. Ground support systems are composed of rock reinforcement (rock bolts or cable bolts) and surface support (mesh or shotcrete). In terms of surface support, fibre-reinforced shotcrete is increasingly seen as the industry preferred solution when difficult ground conditions are experienced, including areas of high seismic hazard. A thick layer of shotcrete is certainly strong but it is by no means flexible. Normal weld-mesh has some flexibility, but it is not very strong. The Australian Centre for Geomechanics (ACG), in collaboration with Onesteel Reinforcing Pty Ltd, is currently working on a new high-energy absorption mesh that combines strength and flexibility. The new mesh can be installed with a jumbo, in a similar way as the widely used sheet of weld-mesh. This paper describes the development of this new mesh system.

Jan 1, 2008

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

By P J. Scales, D Boger

Technological advancements in mineral processing have increased the feasibility of refining low-grade ores. Because of this progression and continual depletion of high-grade ore deposits, much larger volumes of waste material are produced. At the same time, increasing environmental legislation and cost competitiveness dictate that these wastes be disposed of in a manner that is both environmentally acceptable and economically viable. To achieve these criteria, many mineral processing industries are dewatering waste streams in order to reduce the volume of tailings and increase water and reagent recovery. The subsequent dry disposal of these highly concentrated mineral tailings requires a thorough understanding of the effects of dewatering on the flow characteristics. Dry disposal represents a paradigm shift in engineering. The tailings are engineered to suit the disposal requirements, as opposed to engineering a facility to accommodate the tailings. It is therefore important to understand how the material properties and operational parameters can be modified to produce the desired tailings flow and deposition characteristics. As concentrated suspensions usually exhibit non-Newtonian behaviour, determination of the disposal plant operating conditions requires a thorough understanding of the rheological characteristics of the material. The implementation and optimisation of dry disposal methods involves three concurrent and interdependent rheological studies to determine:the concentration required to achieve the optimum spreading and drying characteristics of the tailings once deposited; the optimum conditions for pipeline transport; and the feasibility of dewatering the slurry to the required concentration. The paper presents an overview of the issues pertinent to management of the flow properties and processing of dewatered waste streams.

Jan 1, 2002

By Perring CS, Barnes SJ

The nickel exploration boom of the late-1960s and early-1970s led to the discovery of numerous komatiite-hosted nickel sulphide deposits, associated with variably serpentinised bodies of olivine-rich cumulates. Subsequent research has shown the importance of volcanological processes to understanding the genesis of these deposits. Crucial developments have come through consideration of the fluid dynamics of magmas and magma-crystal mixtures, through observation of the dynamics and geometry of modern day basaltic lava flows, through application of theory and experimentation on the kinetics of crystal growth from magmas, and most importantly from extensive detailed field mapping of komatiitic sequences in the Yilgarn Block and elsewhere. From these studies has emerged a new integrated view of the volcanological setting of komatiite-hosted deposits, and a recognition that a complete continuum of deposit types exists. Nevertheless, komatiite associated magmatic nickel deposits generally fall into two overall types based on the nature of the sulphide ore. In the first type the bulk of the ore is either massive Fe-Ni-Cu sulphide or a variable mixture of massive sulphide and an ore characterised by olivine crystals in a continuous matrix of sulphide occupying between 30 and 75 per cent by volume of the rock (called Matrix Ore). Nickel grades of massive sulphide ore range from 2 - 20 wt% and those of the matrix ore generally fall in the range 1 - 5 wt% (average 2.5 wt%) Ni/Cu ratios of the sulphide fraction are generally >10.

Jan 1, 1996

By D Ziaja, W Jaspers

A brief history of the development of pneumatic flotation cells from early in the 20th century to the present day and a comparison to conventional cells demonstrates the efficiency and simplicity of design and operation of the ænew generationÆ of pneumatic cells. Recent successful testwork on phosphate minerals in the USA and a variety of coal types in Australia confirm the utility and efficiency of the design. The key aspects of this technology are improved recovery and selectivity with lower capital expenditure and operating costs.

Jan 1, 2005

By Thomas W

Due to record low tin prices and an uncompetitive position in world markets, the Renison tin mine has undergone three major phases of restructuring in the last three years. This has involved substantial job losses, almost all of which have been through voluntary retrenchments. Retrenchments took place in 1988, 1990 and 1991.The last phase of restructuring was the most dramatic, as many aspects of the operation of the mine were changed. New pay structures were introduced, and the miners' contract system was scrapped. Drastic pay cuts occurred in many areas, although the opportunity was also taken to increase pay at some of the lower levels where inequities existed. Work practices were changed, as was the management structure.

Jan 1, 1992

By Streichfuss M, KeBler H-W, Burgwinkel P

This paper describes the design of an expert system used as a part of a diagnostic system for diesel hydraulic drives. A PC-based diagnostic system ruDi (KeBler and Burgwinkel, 1993) was developed to minimise the time for diagnosis and repair work of vehicles with diesel hydraulic drives used in the mining industry. One part of ruDi is an expert system that helps to locate errors in any of a vehicle's subsystems, and supports technicians in removing the cause of a malfunction. Apart from the standard knowledge of diesel engines and hydraulic transmissions, the expert system supports the interpretation of the data obtained during sophisticated engine analysis tests such as high-resolution speed analysis or high-pressure analysis of the diesel injection system. The expert system is designed to diagnose various vehicles of the same type. Data for each vehicle is stored separately allowing checks to be carried out individually for each machine. An additional feature of this system is a database interface to a Maintenance Planning and Control System (MPCS) that allows an automatic generation of work orders for the defects found during the expert system sessions.

Jan 1, 1995

By A S. M A Haseeb

Zircon is the second in abundance among the heavy minerals occurring in the beach sand along the coastal belt of Bangladesh. In this study a detailed characterisation of Bangladesh zircon extracted at the pilot plant of the Bangladesh Atomic Energy Commission at CoxÆs Bazar has been attempted using chemical analysis, X-ray diffraction and optical microscopy. From the chemical analysis it is found that Bangladesh zircon has a purity of 95.88 per cent. The main impurity in Bangladesh zircon is titanium oxide (3.01 per cent). This is followed by iron oxide (0.42 per cent). A number of other oxides are also found. Microscopic study revealed that Bangladesh zircon has an elongated, prismatic shape with pyramidal termination in about half of the grains while the rest are more or less rounded. Some fractured and irregular grains are also found. Bulk sample of Bangladesh zircon in the as-received condition shows a yellowish brown color. However, individual zircon grains are seen to be almost colourless and transparent under polarised light. XRD study confirmed good crystallinity in the sample. Under the microscope it is found that zircon grains constitute 94 per cent while total impurities amount to six per cent in Bangladesh zircon. This result agrees fairly well with the chemical analysis results. Microscopic study identifies oxides of titanium (both rutile and ilmenite) to be the main impurity, in conformity with the findings of chemical analysis. Further, monazite was also identified as an impurity under the microscope. An iron bearing coating is also found on a few zircon grains. Most of the impurities found in Bangladesh zircon exist as discrete minerals.

Jan 1, 2000

By Robins R. G

The dissolution of metallic copper powder in aqueous solutions of cupric sulphate under the influence of ethylene gas was investigated. The dissolution reaction stoichiometry obtained was: Cue+(aq) + Cu(s) + 2C2H4(g) = 2(CuC2H4)+(aq) The rate of formation of the copper (I)-ethylene complex in the above reaction was studied in a laboratory autoclave and the effect pH, temperature, ethylene partial pressure and initial concentration on the dissolution rate was measured experimentally and expressed theoretically in terms of several simple conceptual kinetic models. The results led to the selection of optimum conditions for the reaction and the suggestion of an "ion-molecule reaction" mechanism to explain the very low activation energies for the reaction system. The area of application of this reaction lies in the direction of refining impure copper such as cement copper. Several experiments were performed in which an acidified solution of cupric sulphate under ethylene pressure was used to dissolve copper from the cement copper powder in the form of the copper (I)-ethylene complex, followed by the release of gas pressure to disproportionate the complex and precipitate a purer metallic copper.

Jan 1, 1987

By Juniper LA

ERM Consultants Pty Ltd was established in 1980 for the purpose of introducing a disciplined coal technology and power station planning service, to support Australia's efforts in establishing a major export steaming coal industry. At that time, major coal exploration programs were mounted on more than 50 potential export coal deposits with proven open-cut reserves to export 200 Mt/a of coal. The fact that Australia achieved an export trade of only 30 Mt/a, equivalent to the energy requirements for a population of around 5 million people, illustrates the very small achievement to date. The main reasons for this small export steaming coal growth have been: 1. Failure to convince potential overseas coal buyers of the benefits of coal-fired power generation, and the ability of proper power station design to overcome environmental problems, and achieve reliable operation and long life when burning Australian coals. 2. Failure to promote Australian power engineers to advise on the use of Australian coals, resulting in Northern Hemisphere power station experience dominating in market countries. 3. Failure of governments to draw on privately practising Australian power engineers and coal technologists in technical workshops, presentations and assistance to overseas countries, to ensure that personnel whose business it was to serve the follow-on needs of countries were readily available. The result of these failures has been that: 1. Only a fraction of prospective overseas coal-fired power projects have proceeded. 2. Australia has had no influence in the design of overseas power stations to ensure that potential customers would be confident that Australian coals could be reliably burnt in their boilers.

Jan 1, 1987

Naturally occurring rutile contains approximately 96 per cent titanium dioxide (Ti02), whereas the product from the ilmenite reduction - aeration upgrading process, "sub- rutile", contains only about 92 per cent Ti02. Therefore, there is an-incentive to lift the quality of sub-rutile by removing transition metal impurities, in order to supply a more valuable and marketable product, particularly for the chloride-route pigment producers. Previous studies have shown that the sub- rutile residual iron content (of approximately 4 per cent) and residual manganese content (of approximately 1.5 per cent) are chemically bound within the titanium-oxygen mineral lattice, and are most difficult to remove by simple leaching methods. In attempts to improve their eventual removal, a simple process modification has been successfully investigated in laboratory scale trials. Transition metal sulphides have been formed in the reduced ilmenite by using a "sulphur-doping" technique during reduction (metallization) conducted at controlled temperatures. These compounds give rise to greatly enhanced dissolution of the unwanted transition metal constituents during the sub- sequent aeration and acid washing steps. Thus, the manganese content of the final sulphur- doped, reduced-aerated, acid washed product can be reduced by about 90 per cent to 0.2 per cent, and the iron content by about 70 per cent to less than 1.5 per cent, in comparison with those levels remaining after unmodified pro- cessing. Additions of sulphur as low as 2 per cent of the weight of the ilmenite have proven satisfactory. Preliminary studies reveal that the modified process is economically feasible. These results suggest that the sulphur content of the Collie coal char used in an unmodified reduction step must exert some influence on the eventual removal of iron and manganese during aeration and acid washing.

Jan 1, 1973

By Scott B. R

Bougainville's copper mine is located on the west slope of the Crown Prince Range on Bougainville. A high grade copper concentrate is produced for sale to overseas customers. Production planning which was originally based on pilot plant data has developed progressively since commissioning of the concentrator in 1972. Pilot plant data and mine sampling have been supplanted by the correlation of concentrator performance with ore sources, as the basis for short term planning. The influence of accurate sampling is reflected in 1. hourly shift control, 2. the daily milling statement, 3. the prediction of the characteristics of ore from various mine locations, 4. production reconciliation, and 5. the control of copper losses. The mechanical and electrical failures of the original sampling system emphasized the need for a reliable, automatic sampling facility. The development of a pneumatic drive mechanism, which has now been fully field tested, was undertaken.

Jan 1, 1976

By Heape JM

Production from the Cattle Grid orebody commenced in August, 1974. This followed a recent discovery arising from an extensive exploration programme involving stratigraphic drilling, geochemistry and geophysics. Located some 4 km west of the original copper occurrences at Pernatty Lagoon the discovery was found to contain 4.6 million tonnes of ore averaging 2.4% copper. The ore is a "sandstone copper" type localised near the disconformity between two Precambrian (Adelaidean) stratigraphic units, the Pandurra Formation and the Whyalla Sandstone. The mineralisation roughly follows the interface between these units and occurs in fractures, vugs and along bedding planes. The mineralogical character of the ore is somewhat complex consisting of chalcocite and bornite, with associated chalcopyrite, sphalerite, pyrite and other less common sulphides. 1. Senior Geologist, Pacminex Pty. Limited, Sydney, N.S.W. 2. Mine Geologist, for Mt. Gunson Mines, Pacminex Pty. Limited, Mt. Gunson, S.A.

Jan 1, 1975

By Meunier G, Davis J, Koperski G

The dry processing of mineral sands concentrates can result in the generation of significant amounts of airborne dust. The radioactive component of this dust has implications within the context of work environment health codes. The last four years have seen considerable investment in dry plant equipment enclosure and dust extraction systems, with resultant reductions in plant ambient dust levels. Simultaneously, an industry wide program was started to examine the origin, nature, mineralogy and radioactivity of the airborne dust. The major findings of this study have been: ò confirmation that monazite was the only significant source of dust radioactivity. ò recognition of two sources of dust: - agglomerates of finely divided ilmenite-rutile alteration products, which are formed by the removal of surface coatings and particles. - abraded mineral fragments, which reflect the mineralogy of the parent particles.

Jan 1, 1991

By J Czerwinski, M Kasper, M Wyser, N Heeb

The VERT project 1993 - 1998 laid the technical foundation for curtailing the emission of fine particles from diesel engines at Swiss underground workplaces. The targeted maximum was 100 ¦g/m3 EC. Extensive laboratory and field investigations demonstrated that this specification is only attainable with modern diesel particulate filter (DPF) systems that almost eliminate particles in the entire lung penetrating size range from 20 nm to 2.5 ¦m. In January 2000, Switzerland mandated compulsory particle filters in underground workplaces, particularly in tunnelling, irrespective of engine age, size and type. After the implementation, the particle concentration in the respiratory air was below 40 ¦g/m3 EC, compared to earlier values of up to 750 ¦g/m3 EC. Deployed DPFs have proven filtration rates of 99 per cent in the entire size range of alveoli intruding particles. The DPFs are as durable as the engine, suffer no ageing and require minimal maintenance. The failure rate is below three per cent annually. Of the 6000 retrofitted construction machines in Switzerland, about 400 are deployed underground. Prerequisites for this quality are a sophisticated certification procedure, electronic monitoring of DPF operation and meticulous periodic exhaust gas inspection of the engines.

Jan 1, 2005

By Childs G, Ritchie IC

This paper describes the principle and operation of small hydrocyclones for use in the coal, minerals and other process industries. The principles for selecting a hydrocyclone for an application are also discussed. Typic- al uses and installations in various industries are described.

Jan 1, 1984

Since the 1970s we have seen a marked corporate response in terms of the environment. In part this has come from regulation but it has largely come from stakeholders and the community. We now see a similar trend towards sustainability. The Brundtland (1987) definition of sustainable development provides a direction for advocates: the advance of human prosperity in a way that does not compromise the potential prosperity and quality of life for future generations. In my view its three essential components are: economic, environmental and community. The Global Mining Initiative and the contributions to the Rio World Summit and the Johannesburg World Summit on Sustainable Development indicate that sustainability is being taken very seriously by the mining industry. But does the minerals industry really embrace sustainability as they claim? There is a view that in reality sustainability is a non-event and that the triple-bottom line approach is only a convenient catch-cry for companies who are actually focussed very strongly on the economics part of the equation. Chemical engineers are showing a strong trend to more sustainable practices and the chemical industry has shown real commitment to research into developing sustainable processing systems. This requires a framework for thinking and design and the chemical industry is demonstrating true innovation as it moves towards æno wasteÆ technologies. Whilst there are limits to the rates of change that can occur the minerals industry should also be moving in a much more determined manner towards the notion of processing of products designed for whole-of-life cycle û with minimum/no waste. But is the minerals industry just paying lip service to the importance of research to sustainability?Several common themes influence the science and innovation agenda in Australia, which will affect the development and adoption of innovations by AustraliaÆs minerals sector. First is the well-proven link between peer-reviewed scientific excellence and commercial application. Second is the rise of multi-disciplinary Mode 2 research, which has developed in response to the complexity of problems faced by contemporary researchers, which are best analysed by combining expertise from two or more disciplines. Successful innovation outcomes, in any field, including minerals processing, is promoted by Mode 2 research which benefits from greater levels of networking and collaboration. Kofi Annan in his Message to the World Social Forum puts it very succinctly æThe way forward lies in finding constructive solutions togetherÆ.

Jan 1, 2004