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By N Murthy

Alumina is a major impurity in Australian iron ores and as the higher grade ores become depleted there will be a stronger focus on treating lower grade haematite/goethite ores and developing suitable beneficiation techniques to reduce the alumina content. High alumina in iron ore is deleterious in that it can:• produce slags with lower desulfurising capacity,• reduce sinter/pellet strength and quality, and• produce higher slag volume and increase slag viscosity.Meeting iron ore quality specifications for alumina by blending ore from different sources will eventually be insufficient. Hence, innovative flow sheets based on new and commercially available technologies will be required. Their advantages and disadvantages, the testing methodologies and the challenges and diffi culties involved in reducing the alumina content of iron ores are presented and discussed.

Jul 11, 2011

Underground mining in the West Moreton coal field started in the 1870's. Subsidence related to coal mining activities is an ongoing problem facing planners and developers in the Ipswich area in South Eastern Queensland. The history of coal mining in the area over the last 110 years has left the legacy of periodic surface instability in several areas. In general, modern engineering analysis with current mining methods combine to create predicatable analysis of surface stability and movement. Where old workings using several variations of the bord and pillar system are affected by current activity, the predictibility of the surface movement is greatly reduced. Geological complexities further complicate the analysis. Mining and the related dewatering affects the stresses on pillars in old workings. This is caused by reducing buoyancy effects caused by changes in the water levels in old workings. Of particular relevance is the depth of workings and strength of the coal and overburden. The type of subsidence affecting the surface can range from localised pillar failure, to roof failure and potholing and the likelihood of the particular form of subsidence can be assessed from studying the workings in relation to the stratigraphy and structure of the coal measure Formations.

Jan 1, 1988

By Richards BG, Komdeur W

Instability in spoil piles and in high wall slopes in natural overburden has been ex- perienced at Utah's Goonyella Mine since com- mencement of operations in early 1971. Annual production targets, although gener- ally met since the commencement of operations, required modifications to stripping and mining techniques and the rapid re-scheduling of oper- ations around unstable areas, but culminated in the earlier than planned acquisition of addit- ional stripping equipment. An understanding of failure mechanisms was developed within a collaborative study of pitwall instability between Utah Development Company and the C.S.I.R.O. Division of Applied Geomechanics. Results showed that pitwall instability occurs as structurally controlled deformations along planar failure surfaces; spoil pile failures are precipitated by moist- ure ingress and subsequent loss of strength of base layer materials; highwall failures de- velop over areally extensive bedding planes in conjunction with inclined and subvertical fractures caused by overburden blast damage.

Jan 1, 1978

Underground mine ventilation is now com monly simulated on a digital computer. Such a programme, incorporating natural ventilation has been modified by others to account for methane emission and elevated local tempera- tures. At Wollongong University, the pro- gramme was further developed and extensive interactive graphics incorporated such that any view of the three dimensional mine could be viewed, and superimposed upon that view are areas where a nominated parameter has exceeded a particular value - generally at a nominated time after a particular event and usually a fire/explosion of one type or another. A further programme was developed such that up to 20 'times' could be examined at a particu- lar location after say, a fuel rich fire at some other place in the mine. The output from this programme includes a plot of methane 1, smoke 1, temperature, pressure and air flow versus time - a most useful graphic to observe the limits of safe attendance in a particular Airway.

Jan 1, 1983

By Smith R. N

The Olympic Dam copper-uranium-gold-silver deposit is located approximately 520km north-northwest of Adelaide, South Australia. The deposit was discovered in 1975 by the Exploration Division of Western Mining Corporation (WMC). A joint venture, to facilitate development of the deposit was formed in mid 1979 between WMC (51%) and the British Petroleum Group (BP) (49%).

Jan 1, 1990

The Devonian Mount Morgan gold-copper deposit was situated on the western margin of the Calliope Volcanic Are assemblage, in the northern New England Orogen. Recorded production from commencement of mining in 1882 to mine closure in 1989 stand

Jan 1, 1994

By Lu T. K

A new type of rockbolting system, the self drilling rockbolt, has been studied to develop a 'single pass' bolt for use in rockbolt installation in underground engineering. This single pass bolt forms the basis of a Rapid Face Bolting system which will reduce the amount of time spent in securing a roof during the operation of a continuous miner in the development of a panel.The installation efficiency and anchorage tests were performed in the laboratory on the self drilling bolt and the traditional resin anchorage. bolt. The results of both bolts are cmmnared.

Jan 1, 1993

By Baczynski NR, Fagan MJ

A 3050m long section of a 1.65m internal diameter tunnel is presently under construction in the Brisbane area by means of the pipe-jacking method. The soils along the alignment had been deposited in a deltaic/estaurine environment and rapid changes in soil type occur. The tunnel passes beneath several extensive bodies of surface water. Groundwater problems have been experienced with tunnelling through alluvial sands and gravels. Details of the ground conditions, the pipe-jacking method used and tunnelling experience are discussed in this Paper.

Jan 1, 1987

By Zhen Y. Y, Cook A, Jell J. S, Fleming P. J G

Remapping of the Burdekin Basin has resulted in subdivision of the three interfingering basin-wide megafacies previously recognised in the Early to Middle Devonian Fanning River Group. Eleven carbonate and siliciclastic facies are now identified within the three megafacies, representing coastal plain, shoreline, nearshore, and shallow marine shelf depositional environments. The facies reflect two phases of a major transgression. An initial phase, in the Early Devonian, was confined to the far north of the basin, whereas a second, main phase, resulted in the encroachment of the sea from the east or southeast in the Middle Devonian.The proposed depositional model begins with the drowning of a coastal plain and the transgression of shoreline and nearshore facies between granitic and metamorphic headlands and/or islands. This was followed by the deposition of a patch reef and fringing reef complex including stromatoporoid and coral bioherms, biostromes, and oncolitic, crinoidal, and brachiopod-dominated banks/shoals, together with foreslopes and submarine channels, carbonate rubble deposits and terrigenous sediments. Sedimentation during the peak of the transgression was dominated by sheltered carbonate shelf facies, the maximum, flooding surface being recognisable across most of the Burdekin Basin. Progradation of muddy and sandy nearshore bay and shoreline facies soon followed, terminating carbonate deposition.

Jan 1, 1990

The paper presents an overview of the mining industry of Papua New Guinea. Although the Bougainville problem is still unresolved, new mines like Ok Tedi, Misima and Porgera, which have come on stream during recent past, have raised hopes of sustained growth period in the industry. Kutubu Oilfield is also being developed in the Southern Highlands and the oil production has commenced from July 1992. Government revenue from these mega projects will increase five-fold during 1993 and 1994. A new mine which is being planned is the fabulous Lihir Deposit, on an island renowned to be full of gold. Gold occurs within a volcano which still contains high temperature ground water because the system which created the deposit is still geothermally active.In Papua New Guinea, problems of environmental management are far easier to tackle than those of a socio-political and economic nature involving compensation payments to the landowners and the distribution of royalties and taxes between the national and provincial governments. At the socio-political level, the country has not been able to resolve the problems of land rights versus mining rights. Whenever mining starts in a big way, it raises people's expectations to a very high level, which then becomes the focal point of dispute between landowners, provincial governments, national government and mining companies. A new system called 'Forum' has been tried to bring all parties together and son out the issues. The system appears to be working well in new mines like Ok Icdi, Porgera, Misima and Kutubu Oilfields.

Jan 1, 1993

The Kunwarara magnesite deposit is the largest known magnesite (MgCO3) deposit in Australia. It is located under black soil plains to the north of Rockhampton in Queensland. The deposit consists of magnesite nodules set in a fine-grained sandstone, siltstone and mudstone matrix. The magnesite is derived from weathering of serpentinite in adjacent hills and transport of magnesium in solution to a Tertiary/Quaternary river system. The magnesium has come out of solution in the active river system, and combined with atmospheric and biogenic CO2 to form magnesite nodules. The magnesite can be very pure with certain varieties up to 98 per cent MgO (LOI free). The deposit has been mined since 1991 and processed into magnesia (MgO) which is sold into refractory, agricultural and other markets. The geologist is an integral part of the small mine technical team. The role of the geologist includes characterisation of the ore through drilling and bulk sampling, supervision of geological aspects of mining and assistance in the optimisation of ore processing.

Jan 1, 2000

By Tumilty JA, Douglas WD

With a view to characterising activated carbons with respect to their ability to adsorb gold from cyanide solutions, an attempt was made to establish correlations between the equilibrium capacity constant of the activated carbon for gold (k value) and five other parameters. These parameters were percentage ash content, iodine number, methylene blue value, surface area, and pH respectively. Twenty four different proprietary brand activated carbon products were examined, the correlations being established by means of linear regression analysis. It was shown that a significant correlation only existed between k and pH value. This was interpreted in terms of the presence of oxide complexes on the activated carbon surface. Further test specifications as developed at the Anglo American Research Laboratories are also outlined with a view to the selection of activated carbons suitable for use in' a carbon-in-pulp operation. Methods for assessing both the capacity and the kinetic response of carbons for gold adsorption are presented, while the measurement of attrition resistance, particle size distribution and moisture and solubles content is also outlined. The measurement of the capacity constant for gold adsorption together with attrition resistance are considered to be necessary in the initial selection of a suitable carbon.

Jan 1, 1982

By Clift N

Lead concentrate from the Isa and Hilton lead-zinc concentrators of Mount lsa Mines Limited is smelted at Mount Isa to produce a lead-silver bullion. This bullion is cast into four tonne blocks and shipped to Britannia Refined Metals Co Ltd, NorthDeet, England and to plants in Asia for refining and marketing. The traditional treatment stages at Mount lsa are sintering, smelting, and drossing and casting, with some of the sinter plant feed being pre-treated through an Isasmelt plant.A commercial scale lsasmelt based lead smelter was commissioned in early 1991.

Jan 1, 1993

The Ranger Project Area covers 78.6sq km and is approximately six km east-west by 14km north-south (Fig. 1). The area is known to con- tain two uranium orebodies, Ranger No. 1 and No. 3, two uranium occurrences, Anomalies 4 and 5 and three significant radon anomalies, Ranger 18, 19 and 48. The Ranger No. 1 and No. 3 Orebodies con- tain approximately 120 000 tonnes of U308 in highly chloritised metasediments of the Lower Proterozoic Cahill Formation. The orebodies occur as suboutcrop and exhibit significant radiometric anomalies. These occur within approximately 400m vertically of the projected unconformity with the sandstone of the Middle Proterozoic Kombolgie Formation. Oxidised and reduced uranium minerals occur in quartz-rich schists containing variable muscovite, chlorite and sericite and in the chloritic matrix of chert breccia. Secondary uranium minerals namely saleeite, metatorbernite and gummite associated with earthy iron oxides occur from the surface to 50m depth in No. 1 Orebody and up to 80m depth in No. 3 Orebody. Below the oxidised zone, uranium occurs as pitchblende finely disseminated throughout sequences of quartz muscovite chlorite schist up to 150m thick and as open space fillings in zones of structural deformation. The uranium-bearing schists directly overlie up to 300m of dolomite and magnesite containing minor interbedded schist units and are themselves overlain by approximately 2 000m of more micaceous schists of the upper part of the Cahill Formation. Regional metamorphism has occurred to at least amphibolite facies and has been followed by retrograde metamorphism to a greenschist facies equivalent. The metasediments are intruded by granitic pegmatites and dolerites. Uranium is associated strongly with chlorite of which there are at least five textural varieties. Not all of the various generations of chlorite have associated uranium. Graphitic schist horizons occur which are often less than one metre thick and discontinuous. These are best developed at the base of the quartz chlorite schist sequence where uranium grades up to 1 000ppm U may extend for several hundred metres beyond the main ore zone. Uran- ium is not common in the carbonate sequences and only occurs in chlorite segregations in disrupted zones. The unoxidised ore contains sulphides, mostly pyrite, which are low in abundance (

Jan 1, 1984

By S Ferguson, G Noble

The mining industry is facing economic pressures to treat more challenging and lower grade ore types, as well as pressure relating to environmental impact and social license to operate. Preconcentration through bulk ore sorting has the potential to benefit all these areas by enabling mining operations to divert material of low economic value prior to processing, thereby achieving higher feed grades and recovery, while reducing the processing plant and tailings dam footprint and capital required throughout the life of mine. The effectiveness of bulk ore sorting depends on the heterogeneity of material at the measurement location, as well as the accuracy and precision of the measurement. An understanding of ore heterogeneity can be assessed using drill core data, which provides metre by metre elemental assays. This paper reviews such data and assesses the grade distributions over different scales, which suggests that sufficient heterogeneity exists at mining scales to allow the potential for bulk ore sorting. Prompt Gamma Neutron Activation Analysis (PGNAA) technology has proven to be a successful measurement technique within many industries, including mining. PGNAA was first developed in the early 1980’s for the measurement of the elemental composition of bulk materials on a conveyor belt. Today, Pulsed Fast Thermal Neutron Activation (PFTNA) technology is also applied in elemental analysis of bulk materials and has some advantages for bulk ore sorting. In order to enable effective bulk ore sorting, however, a PGNAA/PFTNA analyser must be designed to provide a representative bulk ore analysis with the necessary accuracy and precision. Examples are presented to provide an understanding of the factors affecting PGNAA/PFTNA performance in relation to effective bulk ore sorting.

Nov 10, 2020

By Romanovsky N. P

The Pacific Mobile Belt (PMB) is characterized by old origin and complex evolution both in time and space. As the global structure, the PMB is a narrow tectonic region dividing two plan-etary hemispheres, viz. the Pacific and IndoAfro-Atlantic ones, the relative shifting of which defines the character of many geodynamic processes in this belt. The PMB features inhomogeneity of structure, special matter composition characteristics, sharply broken-out topography, and intensive fields. Generalized anomalies of the gravitational field closely correspond to the PMB boundaries defined by the real features, i.e. the andesite line and distribution areals of Mesozoic-Cenosoic granitoids. The belt boundary position is controlled also by seismic velocity anomalies at a depth of down to 200 km. The modern PMB deformation is defined by the left-hand equatorial shift and rotation of the Pacific Ocean counterclockwise. This rotation is non-uniform in time and of an oscillating character. The motive forces of the phenomenon are considered.

Jan 1, 1990

By Gardner H. J, Wadsley m. W

Bauxite from the Weipa and Andoom (North Queensland) deposits was treated to provide a low-iron raw material for high- alumina refractories or aluminium chloride manufacture. The operation involved passing crushed, calcined bauxite continuously through a single laboratory shaft furnace. Consecutive sulfidation and chlorination of the iron minerals within the furnace resulted in a beneficiate containing less than 2% (wt.) Fe203 and by-product ferric chloride con- taining only traces of aluminium.

Jan 1, 1979

By Patridge A. C

Observations of coal stockpiles subject to unusual levels of instability showed that the particular coals exhibited 'gap grading', a relative lack of intermediate size particles. This led to a suggestion that fine coal particles within the pile might have been induced to migrate under the influence of water flow and to concentrate in relatively impervious layers, resulting in local water saturation and reduction of shear strength. To investigate this suggestion, a large test column has been constructed and washed coals with various levels of fines content have been subjected to a downward flow of water. Subsequent examination of the bed of coal within the column confirmed the percolation of fines and their concentration into horizontal layers, and showed the development of zones of saturation above those layers. Shear box tests showed differences in cohesion and internal friction angle between coals with different percentages of fines, supporting the hypothesis that fines percolation may lead to decreased stability.

Jan 1, 1995

By Ghose AK

Design and selection of support systems for longwall faces call for in-depth know- ledge of strata mechanics and in particular of strata-support interactions. The paper presents the results of field investigations and analysis of a difficult-to-cave roof using powered supports under a massive dolerite sill in Central India using a state- of-the-art datalogger system. The mechanised long wall face was equipped with 4/680 tons chockshields operated on the IFS mode using a 300 KW DERD shearer. The datalogger system was capable of storing data simulta- neously in 32 channels. The paper describes the monitoring system and the monitoring programme. The system provided useful information on support behaviour, build- up of leg pressures and face convergence during an intense dynamic periodic weighting phenomenon which destroyed the integrity of almost half of the face supports. At this point, the face had advanced by about 197 metres from the barrier. The paper outlines a post-mortem analysis of this dynamic event and provides a critical evaluation of the data collected for understanding strata support interaction and the behaviour of the massive sill in the overburden.

Jan 1, 1992

In the southern part of China, car-bonate rocks outcrop in large areas. Ka-rst develops owing to hot, humid climate and heavy rainfall. In deposits of coal, iron, bauxite, tungsten, tin and base metals exist karst formations within or near the mineralization zones. Three pro-blems should be solved in the mine cons-truction in karst region. The first is the drainage and safety control of karst groundwater. Different methods are used to cope with local hydrogeological con-ditions, e.g. drainage from surface by submersible pumps in wells penetrating groundwater seams; drainage from under-ground drifts which intercept groundwa-ter flow with clusters of holes drilled into karst aquifer or with vertical ho-les drilled from surface to the drift underground; cement grouting to block off channels or to seal a part of aqui-fer; groundwater pollution control; etc. With those measures many Chinese mines of tremendous waterflow were success-fully developed and valuable experiences were gained. The second problem is the stability of buildings deteriorated by surface subsidence due to drainage. The occurence and distribution of surface cavings by drainage were studied.

Jan 1, 1990