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By Dickerson A. W

The most important mining problem facing many of the established surface coal mines in the Bowen Basin area of Queensland is the rising cost of overburden stripping associated with increasing depths to coal. The Dragline-Hopper-Truck Project is one of a number of responses to this problem, and involves the design and construction of an experimental hopper followed by field evaluation of a dragline-hopper-truck mining system.Such systems, if proven feasible, could be used for a range of applications, eg prestripping, extension of depths for single pass dragline operations and solution of geotechnical problems.

Jan 1, 1992

By Linkson PB

The presence of residual cyanide in mine tailings and fill sands may, under specific circumstances, lead to acute and/or chronic cyanide poisoning of the environment and individuals. In this paper, the nature of cyanide contained in mine tailings is discussed, along with the circumstances under which such cyanide would become a hazard. A number of methods for cyanide degradation are reviewed in the paper, with special emphasis being placed on biological degradation (due to its low costs and the non toxic nature of the degradation process itself). Recommendations are made as to the best methods of setting up a biological degradation system, for use in mining Situations.

Jan 1, 1987

By Reid JG, Cutfield S

Considerable quantities of dissolved nickel are lost in the waste liquors from the QNPL nickel treatment plant. Cementation, precipitation and ion exchange techniques were investigated to reduce this loss. Ion exchange was the most successful of the procedures studied and a process for recovering nickel from stripped ammoniacal process liquors was developed in the laboratory and scaled up to plant flow volumes. The system developed uses a carboxylic ion exchange resin operated in a completely ammoniacal cycle. The regenerant is itself regenerable using existing plant, thus the only loss is the stoichiometric value of NH4+ required to displace the exchanged cations from the resin. Existing plant sand/anthracite filter beds have been adapted for use as resin columns containing 3 cubic metres of resin capable of treating effluent at a flow rate of 6000 litres/min.

Jan 1, 1978

Rajasthan of western India blessed with rich base metal and phosphorite deposits. The biogeochemical and geobotanical methods of mineral exploration are greatly used in parts of Rajasthan Zawar, Khetri and Ambaj multi-metal project Gujarat and Jhamarkotra phosphorite deposit. These principles are exclusively based on certain assumptions about the anomalous chemical composition in plants and distribution and migration of indicator elements. Biogeochemical studies for lead zinc deposit of Zawar group of mines were carried out to locate the probable accumulators which could help in prospecting for these metals. The important roots of Impatiens balsamia plants contain 735 mg. of cadmium and crotolaria linifolia 603 mg., melhania futteyporensis 626 mg. lindenbergia muraria 443, celosiu argentia 360 mg. In the Khetri copper belt the vegetation is scanty and the species includes Acacia arabica, zyzypus jujuba and cactus euphorbia.

Jan 1, 1988

Resource rent tax is a form of taxation or royalty, which only become effective at such a time as a pre-determined rate of return has been achieved by an operation. The offshore petroleum industry in Australia is already subject to RRT as is the Roxby Downs (Olympic Dam) Mine in South Australia. Both the mining and petroleum taxation regimes in Papua New Guinea include a resource rent tax component called Additional Profits Tax (APT). The implications of the current form of Additional Profits Tax for shareholder cash returns are that the tax burden on the operation may suddenly increase at some stage in the life of the mine, if and when the threshold level of profitability for the tax to be triggered is exceeded. From that point in time onwards the cash return to the shareholders on the capital invested is greatly diminished. For mining companies in Papua New Guinea, the effective tax rate increases from 35% to 57.75% as a result of the onset of Additional Profits Tax. This tax rate penalty is so severe that there appears to be merit in considering the concept of managing profitability through time rather than purely maximising annual pre-tax profits as is currently the case in most mining operations. This would have the benefit of deferring or perhaps preventing altogether the onset of the tax. One possible method for the effective management of profitability is through the control of average mining grade by cutoff grade manipulation. Traditional cutoff grade theory has usually considered taxation as a direct cost at a fixed or variable percentage of annual profits. As a result of this most analyses are conducted on a pre-tax basis. If tax is included in analyses it is usually present as a time independent function of gross profit. Additional Profits Tax is both time and rate of return dependent and therefore not adequately accommodated by currently accepted cutoff grade theory. A review has been made of the effects of resource rent taxes on both the investment decision-making process as well as possible development and mining strategies which may be employed by mining companies faced with Additional Profits Tax. The review includes examples based on the structure of Additional Profits Tax which is levied in Papua New Guinea.

Jan 1, 1997

By Wilson AC

Permian coal from Western Australia's only producing coalfield at Collie is the dominant fuel used in generating electricity for the State's interconnected grid. Collie coal is sub-bituminous, non-coking and has a low ash, medium volatiles and high moisture content. The seams were laid down in a fluvial basin which extended beyond the Collie Basin and included the Wilga and Boyup Brook Basins at least. Adjacent parts of the southwest Yilgarn Block are prospective for Collie-type basins. In the past few years significant deposits have been delineated within the Perth Basin, specifically on the Vasse Shelf and in the Hill River area. In the former area high quality steaming coals are correlated with the lowest coal bearing member at Collie. The seams are amenable to underground mining and because of their high quality, the coal may have export potential. Sub-bituminous coal deposits of Jurassic age are present in the Hill River area. Exploration has down-graded the prospectivity of the Carnarvon and Canning Basins for sub-bituminous near-surface coal deposits. Tertiary lignite deposits are present in palaeo-drainage systems in the southern part of the State and their potential for development is being evaluated.

Jan 1, 1986

By D A. Kepert, D Clark

During early 2004, Fortescue Metals Group (FMG) began an aggressive exploration and drilling program in the Chichester Range, targeting iron enrichment developed in the Nammuldi Member at the base of the Marra Mamba Iron Formation. The timely recognition by FMG of distinct zones of (hypogene) microplaty hematite (mplH) enrichment overprinted by extensive supergene mineralisation led to an early reappraisal of the geological history of the area and characterisation of the possible structural and stratigraphic controls on mineralisation. Regionally, the Chichester Range dips gently at less than 5¦ to the south, however, detailed mapping shows that this regional limb is overprinted by low amplitude, long wavelength, north/south to northeast/southwest trending folds. The locations of major structures in the Marra Mamba Iron Formation, combined with spectral analysis of known mineralisation, allowed extrapolation and prioritisation of exploration target areas. The delineation under cover and understanding of these structures was enhanced by detailed airborne magnetic data. Recognition that supergene mineralisation was associated with a palaeotopography that continued significantly under cover to the south under sediments of the Fortescue River valley led to the discovery of extensive supergene mineralisation together with additional mplH mineralisation. A model for the landscape evolution and preservation of enriched Nammuldi Member was generated in order to help communicate both the complexities involved with targeting drill holes beneath cover and the potential limits to the lateral extents of mineralisation.

Jan 1, 2005

By Bingwen Z, Fengyi K

The hydraulic-stowing mining method is most effective for mining thick coal seams. It is superior to the sliced cover- caving and artificial mining method and the fully mechanized sublevel-caving mining method for the following reasons - a much higher recovery rate is achieved, there is much less surface subsidence and roof pressure, there is no hidden danger of gob fire, and much less methane emission and coal dust problems, etc.. However, its superiority is overshadowed by its backward stowing technique which makes mechanisation of mining and stowing difficult, causes bleed water interference to production and to the environment and is uneconomic because of the high cost of stowing material. These disadvantages limited its application to coal seams that are difficult and not suitable to be mined by other mining methods. The remedy is in reforming it thoroughly to permit mining of otherwise unminable seams and this paper presents the reformation.

Jan 1, 1992

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in piano--polarized reflected light, colour changes are observed characteristic of the various macerals present. The colour changes appear to be mainly due to interference between light reflected at the upper surface of the film and at the film/coal interface. A variety of source materials for the volatile matter required have been tested, including powdered bituminous coal, coal tars, boron oxide, and certain resins.

Jan 1, 1969

By S Pfaff, R Rajic

In the case when the number of independent variables is greater, a careful design for carrying out tests has to be made in order to obtain, with the smallest possible number of tests, as much as possible neutral information about the influence of independent variables on the dependent ones. Only on the basis of such design and its statistical analysis it is possible to come to right conclusions about the function of the whole system. The influence of pressure, temperature, humidity and granulation of the coal upon the resistance to pressure and the water absorption of the briquettes has been tested, with the aim to examine how each of the two dependent variables changes depending on the values assumed by any of the four independent variables and which of the mentioned independent variables significantly influences the dependent ones. The full factorial design with 16 experiments and the central composite design with 27 experiments have been applied. The influence of the independent variables upon the dependent ones has been examined by applying the analysis of variance. The influence values of individual factors and their interaction upon the dependent variables have been stated as well as coefficients of curvilinear equation.

Jan 1, 2003

For the last decade Australia has been the leading exporter of both steam and coking coal. In the ten-year period 1989 - 1998 steam coal exports increased by 93 per cent and metallurgical coal exports increased by 50 per cent. However, profitability of the steam coal sector has been disappointing. The coking coal sector, especially the hard coking coal segment, has fared better but its profitability was more because of its ability to maintain relatively high prices rather than its inherent productivity. Until quite recently the Australian coking coal sector was widely expected to be able to maintain this comfortable state without undue effort for the three major æpartnersÆ; the companies, the State Government and the unions. But coking coal could now be heading down the path followed by steam coal that ends with long-term over-supply and, despite steady improvements in productivity, poor profitability. Steam coal entered the ænewÆ era of long-term over-supply some years ago. Over-supply was due to the rapid increase in production in Indonesia, often from new mines and Australia. AustraliaÆs production rise was underlain by the apparent belief that the best way to lower costs was to increase production. In the first couple of years costs didnÆt fall much but the additional tonnage was sold at lower and lower prices into the spot market. By mid-1998 the difference between the contract price set with Japanese utilities and spot sales was often in excess of $US12 per tonne. Japanese contract prices and tonnages have since fallen significantly. Steam coal has moved from being a product to being a commodity. Any profits are due more to the low Australian dollar rather than inherent mine productivity. Seaborne coking coal trade has been dominated by Australia, Canada and the USA, with the USA becoming less competitive. Unfortunately, when the Queensland capacity expansion was well down the pipeline, the Asian financial crisis occurred and the Japanese economy entered what appears to be a long-term recession. Contract prices fell 18 per cent, tonnages decreased and some mines have been reclassified as supplying lower priced coking coal. The paper analyses past and expected future trends in labour and mine productivity, rail freight and FOB export port cash and total costs of the Australian steam coal and coking coal sectors and discusses the market outlook for Australia. The future economic viability of the industry is analysed and discussed in the light of the rapidly changing global environment.

Jan 1, 2000

Every step on the path from the mine to the smelter invites a comparison between material inputs on one side and outputs plus accumulation on the other. Or put simply, between what you think you have produced with what you find you have at hand. The discrepancy between these sets of comparisons is the error. Following that error in a systematic and objective manner is a way to improve the mineÆs measurement systems, that in turn leads to more accurate accounting for ores, metals and concentrates. Because the control of production is so tightly coupled with the accounting of materials, any lasting improvements in materials accounting will benefit the predictions of materials movements and quality. This translates to more reliable planning and scheduling in stockpile management, logistics, shipping and marketing. The statistical tools described are direct adaptations from the long-standing methods used to maintain the quality of manufactured product in the discrete parts industries. Their use in the process industries, of which mining is one, requires some care owing to the continuous nature of ore extraction and its variable properties. The tools can be used for problem diagnostics and as early warning systems. In common practice many professional staff, in attempting to get a perfect reconciliation between expected and observed results, try to explain away the error or bury it completely. The methodology advocated here requires a different mindset because the error must be given pre-eminence for lasting improvement to be realised.

Jan 1, 2002

By Valenti M

A by-product of the lead smelting operations at BHAS is a copper-lead matte typically containing 35% copper, 38% lead and 12% sulphur. A hydrometallurgical treatment process has been developed for the treatment of this matte to recover copper as cathode and results in a lead-sulphur residue which is recycled to the lead smelter. A commercial plant with a nominal capacity of 4000 tpa utilising this process was commissioned during 1984. This plant has been shown to be capable of producing copper cathode at rates approaching 4000 tpa over short periods of time.

Jan 1, 1989

By Linge H. G

The effect of the presence of ore pulp on the adsorption rate of gold on activated carbon has been studied. A substantial reduction in the rate occurs when the pulp is present. The reduction in rate appears to be caused by two effects: permanent carbon pore blocking by ore particles and temporary shielding of the carbon particle surface, slowing gold access to the carbon due to the physical presence of the fine pulp. There is no significant effect arising from the presence of a pulp viscosity modifier even for conditions when mass transport dictates the loading rate of carbon in clear Solution.

Jan 1, 1987

With the proclamation of the Environmental Protection Act, 1971-80, the Environmental Protection Authority and Department of Conser- vation and Environment were established to enhance the quality of the environment. Proposed gold developments of all scales can be referred to the Authority in the form of a Notice of Intent. Environmentally significant projects might then require preparation of an Environmental Review and Management Programme. Current environmental issues include the'effects of clearing by prospectors,, mine dewatering and tailings disposal. INTRODUCTION In the past, the environmental aspects of gold industry related activities have received little attention. However, with the proclamation of the Environmental Protection Act, 1971-80, mechanisms were instituted which allowed both for referral of projects to the Environmental Protection Authority (EPA) and establishment of the Department of Conservation and Environment. As well as providing assistance to the EPA on referred projects, the Department is concerned about a number of environmental issues associated with the gold mining industry.

Jan 1, 1982

By R Farana

The future challenges in mining instrumentation, mainly on future intelligent mines, are to continue providing instruments with the highest level of reliability at the lowest possible cost, and also to take advantage of technology existing in other industries and to adapt it to the mining context. New wireless instruments (smart sensors, smart actuators, smart controllers) would also be very useful, as well as instruments fully adapted to the monitoring of large movements that are observed, in both underground and open pit mines. Mining instrumentation is found to various degrees in most mines, both open pit and underground. Smart mining instruments present a certain number of aspects specific to the environment in which the instruments are installed. Namely, the instruments can be installed either for short-term or long-term purposes. The mining industry is always looking for useful instruments that can provide relevant information on ground behaviour adjacent to mining stopes or permanent infrastructure. The instruments must meet the various criteria, and must also evolve with the new mining technologies that are continuously being implemented. A strong collaboration between the mining industry, research organisations, and instrument manufacturers is the key to meeting these objectives. This contribution describes the current trends on smart sensors and smart instrumentation with Wireless LAN support.

Jan 1, 2003

By J Mauk

Water-rock reactions such as pyrite oxidation and calcite dissolution strongly influence the pH of pit lakes that develop in open-cast mines after mine closure. The Martha Mine, located in world-class epithermal Au-Ag deposit at the southern end of the Coromandel Peninsula, New Zealand, is scheduled to close in 2007, after which the pit excavation will be rehabilitated into a recreational lake; the first pit lake in New Zealand. Mineral distribution maps from XRD results of 130 andesite samples identify regions that could produce or consume acidity in the future pit lake. Maps show pyrite, calcite, adularia, albite, illite and chlorite distribution in the wall rocks. These data identify five alteration mineral associations: potassic, propylitic, weathered, oxidised and weakly-altered. Pyrite occurs in potassic, propylitic and weathered associations, whereas calcite is restricted to propylitic association in the northeast wall. Subaerial, epilimnion, and hypolimnion exposure zones describe the physical and chemical weathering processes that are likely to occur in regions of pit wall, and the potential effects on lake water chemistry. The pH of epilimnion water will depend on the relative abundance of pyrite and calcite in the propylitic association in the northeast wall, whereas hypolimnion pH will depend upon the frequency of whole-lake circulation events that distribute dissolved oxygen to deep lake layer. In mines with diverse alteration associations, mineral distribution maps are an essential precursor for accurately estimating water-rock reactions in pit lake environments. Data may be directly incorporated into a quantitative geochemical model of future pit lake water chemistry.

Jan 1, 2002

The theme of the conference this year is diversification. One way to diversify is through acquisition. The principle underlying the winner's curse is that in competitive bidding situations where the value of the asset bid for is uncertain the winning bid will overstate the true value of the asset. The successful bidder is blessed with the winner's curse. What this paper will explore is to what extent this is true; how acquirers can avoid being blessed with the winners curse; and show how joint venture deal structures are used within the mining industry to avoid the winners curse.

Jan 1, 1996

By Bearman R. A, Parkin R. M

Traditional quality control procedures for aggregates production within the quarry industry rely on off-line laboratory analysis, resulting in poor performance and inconsistent product quality. A high speed on-line aggregate classification system is described here. A product sampling system directs aggregate through an inspection chamber where a novel imaging system digitises the particle geometry. Data processing algorithms extract dimensional data and image features, while a neural network classifier assigns a qualitative shape descriptor to each rock particle. This system provides each sampled batch with a complete analysis of size and shape distributions, complementing a new generation of cone crusher technology to maximise product quality and plant efficiency.

Jan 1, 1995

By Nixon J

Open pit mining began in 1978 at the Woodlawn base metals deposit. For its ten years as an open pit the mine was financially unsuccessful as a combined result of difficult metallurgy and industrial unrest. In 1985 CRA bought out two American joint venturers with a view to going underground and a prerequisite to expending capital on developing an underground operation was to improve the industrial climate, work practices and mining methods.Following feasibility work, continuous production from the underground mine began in 1986 using mechanised cut and fill methods and a workforce trained under a multiskilling program. Men with no previous underground experience were trained by supervisors with backgrounds as miners to undertake all the work that is required with increases in skill levels being rewarded with increases in pay.

Jan 1, 1992