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By White A. H, Vihena M. T M B

Presently, orebody modelling consists basically of fitting a mathematical model to represent spatially a certain geological variable, generally grade. An orebody model is constructed from a set of sample data obtained from various locations in the orebody, thus it is only one form of representation of the true phenomena. Checking the compatibility of the data with the modelling procedure is the most important factor when assessing confidence in the orebody model. The level of confidence in the model will depend on the adequacy of the data set and the validity of the basic assumption required by the modelling method. Fractal geometry is one way of modelling the spatial distribution of a geological variable in an orebody geometry. Fractals can be used to interpolate the Z(x) geological variable at unsampled sites. The concepts of self similarity and self affinity that form the basic assumption of fractal geometry theory which areinvestigated. The population distribution of the geological variable in question must be examined to determine the appropriateness of both fractal geometry and geostatistical modelling methods. The selection of the most appropriate method depends on the available data. A researcher or a practitioner needs to understand the strengths and limitations of the various modelling methods before choosing the most appropriate method. This study investigates the fractal properties of grade distribution using the variogram and some proposed variations as techniques to measure the fractalness. The aim is to assess applicability of fractal geometry theory to modelling ore grade distribution in a deposit. A comparison of the results demonstrates the methods which better capture the spatial behaviour of the variable under study.

Jan 1, 1995

By Plyley WF

Kidston Gold Mine is a 3.5 million tonnes per year operation located 280 kilometres west of Townsville, Queensland. Kidston's ore body consists of 44.3 million tonnes graded at 1.79 grams per tonne gold and 2.22 grams per tonne silver. Full production commenced in March, 1985. During the remainder of 1985, Kidston milled 3.77 million tonnes of ore and produced 213,614 ounces of gold.The ore is comprised of granodiorite, polymictic and volcanic breccias. The degree of oxidation of the rock influences the milling capacity and therefore determines the cut-off grade; ore is categorised as oxide, transition and fresh. The milling rates are 15,400, 12,000 and 9,600 tonnes per day for oxide, transition and fresh ore respectively.The ore is treated in a conventional cyanidation/ carbon-in-pulp plant (CIP). The plant consists of a primary crusher, semi-autogenous grinding (SAG) and ball mills, leach circuit and carbon-in-pulp circuit. Carbon stripping and dore smelting are done on site. The major difference between the Kidston plant and other Australian CIP plants is that a cyclone separation and washing circuit rejects half of the dry tonnage as a sand tail prior to CIP treatment. This difference allows the CIP circuit at Ki.dston to be smaller and makes the CIP less sensitive to the grind circuit product size.

Jan 1, 1986

The Australian Mineral Industry's growth in the last two decades is directly related to the skill and experience of its consultants in mining, metallurgy, geology, finance, management, marketing, and engineering. The role of mining consultants needs to be re-examined, so that the quality of the service they deliver will continue to be adequate for the 1990's. One means of this evaluation is by examining Case Studies in the strategies and difficulties of developing contract and entrepreneurial research.

Jan 1, 1986

By Corbett GJ

Comparisons between individual SW Pacific Rim gold deposits have facilit-ated proposal of a new classification of porphyry-related mesothermal gold deposit types. Carbonate base-metal gold systems form at relatively high crustal levels, peripheral to porphyry intrusions. There is a spatial assoc-iation with major structures which focus fluids from degassing porphyries at depth. Milled matrix intrusive breccias and extrusive maar volcano/ diatreme breccias form as a result of pre-mineralisation phreatomagmatic eruptions. These focus degassing magmatic fluids by the provision of fracture ground preparation, typically within competent host rocks, adjacent to the breccia bodies. Local dilational structures control the form of individual deposits which may contain bonanza gold grades at sites of fluid quenching and/or repeated mineral deposition.Early quartz veining and porphyry-related alteration is common and later gold mineralisation typically occurs in association with carbonate veining and Fe and base metal sulphides as Zn > Pb > Cu. The progressive cooling by mixing of the upwelling mineralised magmatic fluid with descending bicarbonate waters, produces characteristic zonations in carbonate compositions. These vary with distance from the porphyry source, from Ca through Mg, Mn and distal Fe types. Gold mineralisation is preferentially distributed within the Mn/Mg carbon-ates.

Jan 1, 1994

By B OÆNeil

The Trent-Severn Waterway is a 386 km long navigation route through central Ontario between Lake Ontario and Georgian Bay, and is operated by the Parks Canada Agency. Its primary focus is to pass recreational boats through a system of 44 locks. The Big Chute Marine Railway (BCMR) is one site in the system that provides transportation for boats. The BCMR carriage is used to transport boats and their passengers on the inclined railway a distance of 230 m over a natural barrier from one body of water to another, with an elevation difference of 18 m. The unique feature of the haulage system used in this application is the variable angle of the incline from about 20 per cent rise changing to horizontal and followed by 20 per cent decline. In such conditions, unlike as in standard incline haulage, special configuration of hoists and drives is required. On the uphill part of the track, there is a need to have a motoring mode, on the downhill part a regenerating mode and on the horizontal part a combination of motoring and regeneration is required. The original system was built in 1978 and employed four 100 hp dc drive mine hoists to haul the 100 tonne conveyance loaded with 90 tonnes of boats. Due to failures and operational problems with the original system, in 1999 Parks Canada awarded a turnkey contract to ABB for a new, modern system of four single drum hoists. The new system was put into operation in 2000, only six months after receiving the order. The hoists are controlled by digital drives and a digital control system. Due to dramatic changes in the load conditions for individual hoists involved, the new system features many interesting solutions like changing drive modes from speed to torque control and a multiple, regulated braking system. It is a unique hoisting system, which could be also used in mining applications.

Jan 1, 2005

By West RF, Pooley RH

An underground mine, a treatment plant and supporting facilities have been constructed at Lebong Tandai in Sumatra, Indonesia by PT Lusang Mining. Throughput is initially 50,000 tonnes per annum of ore with an inbuilt capability to expand to 100,000 tonnes per annum. Construction proceeded in parallel with design work on a tightly controlled critical path schedule. The very remote location of the mine, the difficult access and the fact that equipment was imported from many parts of the world presented a challenging project management problem. The transport system, which involves road, river and rail and support facilities on site had to be brought into full operation prior to the arrival of major equipment. Mine development involved the reopening of the old access drives and workings, refurbishing two shafts and the haulage system together with redevelopment of old stoping areas and the opening of new stoping areas. Ore production is now from three main areas using shrink and underhand stoping methods. Ore breaking and drive development is with conventional airleg mounted rockdrills and ANFO explosives. Exploration to locate and develop new reserves to replace ore mined is an ongoing activity.

Jan 1, 1986

By Smith F. A, Both R. A

The application of biogeochemical methods in mineral exploration in the semi-arid to and environment of Western Australia was investiga- ted in an area near Norseman. The reliability of these methods was evaluated by comparing trace element characteristics of rock, soil and plants in the vicinity of the Pioneer BB pros- pect. The prospect is located in the south- western part of the Pioneer Dome, where granite gneiss core is surrounded by a 'greenstone' sequence of ultrabasic, basic and sedimentary rocks. Nickel-iron sulphide mineralization occurs discontinuously along one of the basic- ultrabasic contacts. Analyses of unweathered and partly weath- ered rock from diamond drill cores show the ultrabasic rock to be highly variable with re- spect to nickel, copper, cobalt, zinc and manga- nese. Samples of weathered bedrock and over- lying soil were analysed both for total trace element contents and for the trace elements associated with secondary iron and manganese oxides. Approximately 30 per cent of the total nickel content of the weathered basic rock is associated with secondary iron and manganese oxides, compared to approximately 15 per cent in the weathered ultrabasic rock. The soil is partly transported but has a residual component sufficient to provide a reli- able indication of the underlying rock chemistry, although the trace element content of the soil is less variable than that of the rock. Total

Jan 1, 1973

By R Grogan

The Ungay-Malabago polymetallic deposit, currently owned by Lafayette Mining, is located on the eastern end of the island of Rapu-Rapu which lies east of the city of Legazpi in the Philippines. The island is sparsely populated and has largely been deforested by extensive logging some 30-40 years ago.The deposit is situated on a plateau some 200 m asl and lies about one kilometre inland from the coast. The site topography is difficult with minimal flat areas for plant facilities. The region around Legazpi is subject to volcanic activity and though the island is not affected it is in a seismic zone. There is no other mining or other industrial activity on the island, the local inhabitants being engaged in subsistence farming and fishing. These activities place a high level of responsibility on the mine operator with regard to the environment and the provision of employment and training to the local inhabitants. Although no previous mining was carried out at Ungay, shallow pit mining for high-grade direct smeltable copper ore has occurred during the mid-1900s in an area, known as Hixbar, some 2 km west of the deposit This area is currently being explored by Lafayette.

Jan 1, 2002

By Wygralk A, Hallenstein CP

On a world scale, many Mid-Proterozoic fluvial sediments are prospective for low grade, large-tonnage gold deposits. A significant area of the Northern Territory is covered by such Mid-Proterozoic sediments, the gold potential of which has been barely tested. The geological knowledge of these sediments is summarised. The Westmoreland Conglomerate, the basal Mid-Proterozoic formation of the McArthur Basin, has been subjected to detailed sedimentological studies in order to determine the paleoenvironments and to assess the possibility of paleoplacer occurrences. The results indicate that the sandstones and conglomerates of the formation were deposited by braided rivers and debris flows as an alluvial fan which originated in source areas to the north east. The formation contains several upward-fining cycles of sedimentation, which are related to repeated periods of uplift in the source areas. The formation of placer-type gold occurrences is possible in such depositional environments. Very limited heavy mineral sampling has indicated a cassiterite- wolframite-gold suite in the sediments of the Westmoreland Conglomerate. Disconformities at the base of sedimentation cycles are deemed to be the most likely sites for large-tonnage paleoplacer concentrations.

Jan 1, 1984

By M A. Llano-Serna, D J. Williams, L Bu

Tailings dam failures continue to occur worldwide at an unacceptable rate, averaging two events annually over the last 100 years. Furthermore, tailings dams continue to grow in size, increasing the potential release of tailings and water should they fail. Tailings are generally deposited in a slurry state, with the potential to flow if containment is lost. Understanding the generation and propagation of excess pore water pressure on failure is critical to predicting the flow and run-out of tailings. This paper presents numerical modelling using the material point method indicating that tailings run-out processes may be self-enhanced by the excess pore water pressure induced during the collapse of the containment. Moreover, it is shown that geomorphological features, such as the slope and its surface roughness downstream of the tailings dam, influence the pore water pressure dynamics upstream of the advancing toe.CITATION:Llano-Serna, M A, Bu, L and Williams, D J, 2018. Excess pore water pressure induced during tailings run-out, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 377–383 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Klenowski

Rational design of layouts for longwall operations is greatly facilitated by use of an accurate and economical method for predicting stresses and displacements. The displacement discontinuity method (a form of boundary element method) is based on replacing actual excavation geometries by thin slits of the same plan area. This approach allows three-dimensional stress- analysis at a fraction of the cost of alternative methods. The analyses can be readily performed on economical microcomputers, putting the analysis capability within the reach of mine-site personnel. This paper describes investigations associated with the German Creek Central Colliery, the first longwall operation in Queensland's Bowen Basin. The material properties used in the model, in particular the rock mass and goaf properties, have been 'tuned' to fit stress measurements obtained during extraction of the first and second longwall panels at the mine. The study shows that model predictions based on suitably scaled anisotropic rock strata properties are in good agreement with the stress measurements made to date. This model predicts average chain pillar loads significantly higher than predicted by models based on United Kingdom conditions. A working chain pillar design method is proposed using average pillar loads predicted by the numerical model and ultimate strength characteristics given by Bieniawski's formula.

Jan 1, 1988

By Marshall K. I

THE problem of satisfactorily eliminating the fumes and dust which are unavoidably produced in various metallurgical and manufacturing industries is one which has received considerable attention in the past, and has been the subject of much investigation and research. The solution of this problem was urgently desired for two reasons, the principal one being the fact that a considerable percentage of the total process losses in many industries was represented by the commercial values of the fumes and dust that escaped from the stack.The other reason is that, in some instances, the emission of the matter is regarded as objectionable. Various methods have been designed with a view to solving the problem thus presented, and the latest development that has beendesigned is the process of electrostatic precipitation. Continued investigational and developmental work with this process has already demonstrated its applicability to many industries, and new uses to which the process can be put are being opened up. Its use is already widespread, and the economic success that has attended its application in most instances would indicate that its use will become more general in the future.It has proved its ability to treat gases over wide ranges of temperature, and has successfully handled various types of fumes whose chemical characteristics differ very considerably. In many processes it has now come to be regarded as standard equipment.HISTORY OF ELECTRICAL PRECIPITATIONThe first recorded observations on the influence of an electrified insulated wire on gases containing solid particles in suspension was made as early as 1824 by Hohlfeld, in Leipzig. He found that, if he electrified a wire hung in a bottle filled with smoke, the smoke cleared rapidly, and a deposit formed on the sides and bottom of the bottle.

Jan 1, 1923

Tasker (1985) has detailed the accepted practices for constructing polygonal blocks of influerrce in the estimation of ore reserves. Further he suggests that users might fall into traps such as omission or overlap when determining the area of influence for each sample point.As an example of these types of errors Tasker (1985) describes under "Coverage ofthe Area" how 25 per cent of the exploration area will not be included in an equiangular triangular grid where hexagonal blocks of influence are used.The introductory suggestion of Tasker (1985) of "incorrect procedure" by Rudenno (1983) (and Armstrong (1983)) reiterated around the Figure 2a of Tasker (1985), is based on the brief description of the polygonal area of influence by Rudenno (1983). That description is not too different from that given by King, McMahon and Bujtor (1982).

Jan 1, 1985

By Garg R. K

Himalayan ranges on the northern border of India are source of many perennial rivers and suitable sites for large dams have been located therein. However, Himalayas are young mountains and comprise of comparatively weaker rocks having adverse geological features like shear seams, thrust zones, minor and major faults and intense jointing. Tehri dam project under construction, is located in lower Himalayas. It envisages construction of a 260.5 m high earth and rock fill dam and an underground power station of 2000 MW (Eight machines of 250 MW each, four of which will be reversible) installed capacity. This dam will be the highest and the underground complex will be the largest to be constructed in India in the Himalayas. The under- ground complex comprises of 25 km of tunnels varying in diameter from 6 m to 11 m and seven large cavities of various sizes, the biggest being 22 m in width, 194 m in length and 65 m in height. Rock formation in the power house complex belong to phyllites having various joint sets spaced from 0.5 m to 3 m. Due to the poor geological conditions and closely spaced net work of large cavities, the planning, analysis and design of the cavities is a challenging job. Many aspects have to be considered in determining the sizes, locations and orientations of the various cavities taking into account the properties and jointing pattern of rock mass, functional requirements and economics. Correct evaluation of loads and forces is necessary for economical design of supporting system for the various cavities. Rock loads on the roof of cavities and their supporting system will be assessed with the help of the latest methods. The stability of the rock mass around the cavity will be evaluated by elasto- plastic method using finite or boundary element techniques. A scheme of field investigations, laboratory tests and instrumentation for deter- mining rock properties in preconstruction stage and for monitoring behaviour of the underground cavities during and after construction is envisaged.

Jan 1, 1987

As the mining sector increasingly embraces the sustainability agenda, and implements thorough environmental reporting in support of its case for a continued æsocial licence to operateÆ, there is a need for ever-clearer metrics for key areas of impact. It is clear that natural waters are both the predominant pathway and main recipient of the environmental impacts of mining. A new approach to summarising the impacts of mining operations on water quantity and quality is proposed, adapted from an existing generic framework, which is increasingly used to quantify the æwater footprintsÆ of cities and nations. This includes both direct water use and ævirtual waterÆ use, implicit in goods and services used by the mine. In contrast to the existing formulation of æwater footprintÆ, it is here argued that it makes hydrological sense to express the water footprints of mines in areal terms, as equivalent catchment areas. It is also important in the mining sector to capture systematic changes in the scale of impact, which can be anticipated and predictively quantified over the full life cycle. This includes the essentially infinite post-closure phase, during which æremanent water consumptionÆ occurs, either through physical water loss (eg by evaporation from pit lakes) or by ongoing contamination of sizeable flows of natural waters. Methods for assessing the water footprints of mines are now available, and the time is increasingly ripe for them to be applied in earnest in environmental reporting. An example application to a mine in a humid subtropical area of South America is presented. In that case, the mine site itself extended over 106 ha, whereas the maximum water footprint exceeded this by a factor of 27. Although the water footprint can be expected to decline by a factor of ten immediately after closure, sustained evaporation from pit lakes and tailings dams with water covers will gradually increase the remanent water consumption rate, such that the final post-closure water footprint remains about 25 per cent of that encountered during the peak of mining.

Jan 1, 2006

By Baafi EY

Open cut mining in Australia is facing the greatest challenge in its history in attempting to compete not only with other operations internationally, but also with underground operations domestically. Most flat dip and shallow depth surface-mineable coal reserves have been depleted during the last two decades and new open cut operations must extract deeper coal deposits. As open cut coal mines move into deeper areas and the stripping ratios increase, the relative cost of overburden removal also increases. It therefore becomes even more important to design the mine around the optimum overburden removal scheme. The deeper mines are usually multi-seam operations with a more complex geology and with more geotechnical and hydrological problems. Deeper mines are subjected to greater problems requiring more detailed mine planning and design, such as selection of the optimum mining method and pit layout. In planning and design of such operations, the number of alternative methods which need to be considered is consequently greater.Dragline productivity and its stripping capabilities are directly affected by the selection of digging method, strip layout and pit geometry. Every mine has a unique combination of geological conditions. The operating methods that work well at one mine may not necessarily work at another site. Selection of an optimal stripping method, strip layout and pit geometry for a given dragline must be considered with respect to the geological conditions of the mine. With increasing geological complexity of Australian strip mines, it is becoming more important to use sophisticated techniques such as computerised mine planning methods to assist in optimising dragline operations.

Jan 1, 1998

By Fallins J

THE John Darling Colliery, owned by The Broken Hill Proprietary Company Limited, is situated 12 miles south of Neweastle, NSW and about 1 mile from the ocean. The area of the holding is approximately 10,000 acres, about half of which underlies the Pacific Ocean. The area was proved to be coal bearing by diamond drill boring: this method not only proved the coal to exist, but gave the depths from which could be calculated. It also proved the existence or otherwise of heavy faulting, which is a very important factor in the design of the underground lay-out of a mine. The location of shafts had to be carefuIly studied, and, before final selection, the following salient points had to be considered:Railway communications.Flood waters.Boiler feed water.Surface buildings.Probability of coal washing.Underground haulage arrangements.Lengths of roadways from a ventilating viewpoint.Before the shaft sites were finally selected, an underground design was prepared to determine the direction of the main drives in relation to the boundaries of the holding, and the of the coal seam: the latter, being an important factor in this particular locality, was ascertained by a geological survey of rock outcrops in the neighbourhood. Size of shafts was the next subject for consideration. This was determined by output, number of seams to be worked, amount of ventilation required, and, on...

Jan 1, 1930

By De Broglio R

The Mae Moh coal deposit was discovered some 60 years ago by villagers who noticed spontaneous combustion of coal outcrops. The first production began in the 1950's to fuel a fertilizer plant and a 12.5MW power station. During the period 1976 to 1979, three 75MW power station units were constructed on site. These have a total daily coal consumption of some 5000 tonnes and are served by a stockyard of approximately 60 000 tonnes total capacity. Stacked coal is reclaimed by means of a front end loader onto reclaim conveyors. During the years 1983 to 1986 four 150MW power station units were constructed east of the eastern seam subcrop, sons 2 km from the original power station complex. These have a daily coal consumption of nearly 12000 tonnes and are served by a stockyard of total capacity 270000 tonnes, equipped with two stackers and two bucket-wheel reclaimers for a totally mechanised system.

Jan 1, 1986

Mount Isa Mines Limited commissioned the Heavy Medium Plant in August 1982. The first processing stage using Mogensen Sizer 2056 dry screens, experienced unresolvable cloth blinding problems in attempting to separate fine, damp Lead/Zinc ore at 1.7 mm. A large proportion of the fines incorrectly reported to oversize and hence to the wet preparation screens. This wet preparation screen overloading produced multiple operating and maintenance problems. The plant configuration precluded retrofitting any alternative proprietary screen. An internal Mount Isa Mines research and development programme was established to design and build a screen to achieve the required per- formance within the site constraints. The resulting ISA SIZER screen has exceeded metallurgical performance expectations. A `clean sheet' approach to the design also permitted elimination of maintenance difficulties experienced with the Mogensen Sizer. Four `production model' ISA SIZERS were installed in February 1988. The ISA SIZER screen, now fully developed is available commercially and will satisfy many screening plant requirements.

Jan 1, 1988

By Thomas R. J

Following asmallnumberofpollutionincidents involving the death of cattle from ingestion of cyanide that had escaped from gold processing plants, the Queensland Government undertook to develop competent guidelines addressing this problem. These guidelines, "Queensland Government Guidelines on Prevention of Water Pollution from Cyanide Use in Gold Ore Processing", issued by the Department of Environment and Heritage, Department of Resource Industries and Water Resources Commission, cover hydrology and general house-keeping intended to reduce the likelihood of significant impact from a spill or unintentional dis- charge of contaminated material. There are three major advances for Queensland embodied in this Guideline: ò the use of a design approach that gives site specific standards rather than trying to give a multitude of standards broad enough to cover all situations, ò the use of hazard assessment and a "critical period" hydrologi- cal design technique, and ò new monitoring and reporting requirements. The guideline is presented here in a summary form:

Jan 1, 1991