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A failure criterion for coal is proposed in which a distinction is made between brittle and "pseudo-ductile" failure. This criterion is then used in the development of new equations for coal pillar strength, including a transition from brittle fracture to pseudo-ductile yielding. In addition, equations are obtained which allow the äritical minimum pillar dimensions to be calculated to avoid "catastrophic" and "ultimate failure". The use of these formulae is then demonstrated by comparing the results with pillar case histories derived from the literature.

Jan 1, 1986

By L H. Chapman, I J. Kelso, N H. S Oliver

Utilisation of modern 3D visualisation tools, can improve our ability to correlate between different datasets, and thus to produce more accurate geological models. Here, we present an application of such techniques to the Century Zinc Deposit, northwestern Queensland, Australia. This stratiform orebody is the second largest Zn resource in the world (167.5 Mt at 8.2 per cent Zn, 1.2 per cent Pb, and 33 g/t Ag). It is hosted in the Page Creek Syncline affecting Mesoproterozoic shales and siltstones of the Wide Supersequence of the Isa Superbasin. As in other deposits, (eg McArthur River, Lady Loretta, George Fisher and Dugald River), the mineralised sequence is bound by an important regional structure, the Termite Range Fault, which partly intersects the deposit along its Eastern side. This fault is thought have been active during sedimentation and probably also during mineralisation of the lowest part of the Wide Supersequence. The anastomosing geometry of this fault system and crosscutting relationships with other NE trending structures indicate that it was reactivated several times from Mesoproterozoic to at least late Devonian times (>1000 million years in total); as a result, the ore sequence is subdivided into several fault blocks.Using two different computer modeling packages (GOCAD and 3ds max), we have reconstructed and restored the stratigraphic horizon with the highest Zn content, realised a series of isopach maps for each mine scale stratigraphic unit, plotted the three-dimensional distribution of Zn, Pb, Ag, Fe and SiO2, and have begun to evaluate the degree of correlation between thickness changes and sulphide zoning. With this approach it is possible to better understand the timing of mineralisation from a genetic perspective, because the origins of the orebody are controversial. Three-dimensional reconstruction is a vital tool for identification of syn-sedimentary and post-sedimentary fault activity. In conjunction with sulphide precipitation, these are factors that greatly influence the stratigraphic thickness distribution. Post-sedimentary deformation can be recognised directly by core logging and pit mapping, but the effect of tectonic movements during sedimentation (growth faults in particular), that represents a substantial variable when we attempt to reconstruct basin evolution, is difficult to evaluate without this methodology. The 3D models improve our understanding of the local basin architecture, identifying similar grade characteristics at different structural levels and thus suggesting that much faulting and folding are post-mineralisation events. In addition, we identified several growth faults adjacent to thickened layers, representing two possible sedimentary depocentres. These thicker domains apparently relate to the highest Pb content. If further analysis of rocks, thickness and grade distributions support this preliminary correlation, then a syn-sedimentary model for mineralisation might be applied, and would contrast with the sub-surface model for mineralisation of Broadbent et al (1998).

Jan 1, 2003

It is possible from simple gas behavioral theories to develop more complex relationships which allow prediction of transport phenomena such as diffusivity and viscosity of gas mixtures. Such physical data can be used in engineering calculations for both bulk gas movement and gaseous chemical species movement. Both of these are important in the solution of mines ventilation systems. There are specific limits of flammibili!'y of some common mines gases.

Jan 1, 1983

Batterham and Algie began their paper on: `The role of technology in the minerals industry' (1995) by noting that while: it is often stated that innovation is central to the economic survival of mining and minerals processing in the face of global competition, .. . technology is often far from a core strategy in our industry. This point is correct. Throughout the world, as a broad generalisation, mining companies do not value technology development as a principal means of gaining competitive advantage. It is important to understand why this is the case. Batterham and Algie address this question by making distinctions between innovation, technology and research. They note that while: all successful (mining) companies are good at innovation . . . that innovation can proceed without any research and development and that it is innovation that generates the competitive advantage, not research and development per se. In this paper we accept these arguments. However, our focus is somewhat different. Whereas Batterham and Algie took a mining company's perspective on the technologies of mining and processing, we take a broader view of the opportunities for technology development for company Australia but, in order to focus the argument, we restrict our discussion to the area of mining (rather than processing); we focus particularly on mining systems and mining equipment. We begin by looking at the motivation of companies operating in any industrial sector to invest in research and development. Figure 1 recognises four levels of industrial maturity. For companies in the embryonic and growth stages R&D often is essential to initiating and developing the business. Mining, on the other hand, is a mature industry. In mature industries the conventional roles for R&D are to reduce costs, to extend product differentiation, or to develop new technology with the aim of rejuvenating the business. Next we ask whether these general-industry arguments apply to the mining industry. If they do then the mining industry should value R&D more highly; after all cost reductions and business rejuvenation are goals that are worth achieving. On the other hand if, for whatever reason, these general arguments do not apply to mining then this may lead the mining industry to invest only modestly, or not at all, in R&D. In this event, while this may be a rational decision for the mining industry, it may not be in the best interest of a nation like Australia where revenues from the sale of mineral products represent an important part of the country's economy.

Jan 1, 1997

By Ono K, Oishi T

Electrochemical determination of the oxy- gen partial pressure in the Fe-0-SiO 2 ternary systems saturated with solid silica was done by measuring the activity of oxygen in a silver bath in equilibrium with the molten slags using zirconia solid electrolyte galvanic cells. From the data obtained, the activity ~Faii.st composition relations were calculated

Jan 1, 1980

By Liu Y, Campbell K. R

The paper shows how breakage parameters may he extracted from laboratory batch grinding results and how they may used with reference full-scale hall mill circuit data to estimate the likely size distributions of values and gangue in a full-sca

Jan 1, 1997

By Mann T

The use of dolomite as a refractory began in England about 1870 when the basic Bessemer process for the removal of phosphorus from steel was developed by Thomas and Gilchrist.Knowledge of dolomite as a refractory in this country goes back to the early part of this century, at the time when the Hoskins Brothers took over the Lithgow Iron and Steel Works from W. Sandford. The practice then was toimport burned dolomite in casks from England. It is reported that much of the material was powdered when received, but was still serviceable. The earliest. used sources of local stone were in the Bathurst and Mudgee areas of New South Wales, and these dolomites were first used raw. Later, dolomite was burned in cupolas at Havilah near Mudgee, coke being obtained from the South Coast of New South Wales. This plant supplied burned dolomite to the Lithgow steel plant, later to the Australil1n Iron and Steel plant at Port Kembla, and also to the electric steel furnaces at Newcastle, Sydney and Melbourne until the plant was closed down in 1946.The Broken Hill Proprietary Company first obtained its dolomite from George's Plains near Bathurst (this was, really a magnesium limestone) and later from Mount Knowles, a deposit near Mudgee, which was eventually taken over by the CO:plpany in 1918. In 1936 Australian.Iron and Steel acquired from the Southern Portland Cement Company a deposit at Mount Fairy in the Federal...

Jan 1, 1951

The late Carboniferous to early Permian Featherbed Volcanics cover an area of about 3000km near the western margin of the Hodgkinson Basin, in northeastern Queensland. The dominantly ignimbritic volcanic rocks are mostly confined to a single, composite, volcano-tectonic depression, but, along with the associated intrusive rocks, may be divided into two main groups: late Carboniferous I- type rocks and early Permian A-type rocks. Late Carboniferous I-type andesitic to rhyolitic ignimbrites and minor andesite lava crop out in the southeastern, southern, and southwestern parts of the complex, mostly confined to a basin-like depression, or "sag" structure, and are associated with coeval dioritic (and rare gabbroic) to granitic intrusive rocks. Extensive Sn, W and base- metal, and some Au, mineralisation are associated with these rocks, particularly in the southeast. The main part of the complex is of early Permian age, and consists almost entirely of A-type rhyolitic ignimbrite and relatively minor volumes of lava intruded by a peripheral ring dyke of porphyritic microgranite and by resurgent-type plutons of porphyritic microgranite and microgranodiorite. These rocks are associated with sparse base-metal, Au, U, W, and Sn mineralisation.

Jan 1, 1987

It is now 32 years since Walsh's classic publication (1) heralded the beginning of atomic absorption spectrophotometry (AA) as we know it today. During this time, AA has developed into the most widely used analytical techniques for the determination of the metallic elements. The years have seen progressive changes in instrumentation so that today it is a highly sophisticated technique. One area of development in AA that is experiencing renewed attention is in the area of electrothermal excitation. In this technique a flame is not used by the analyte solution is atomised by an electrically heated graphite furnace. For a large number of elements the graphite furnace atomic absorption spectrophotometer (GFAA) is considerably more sensitive than flame work. It is common to be able to detect concentrations one hundred times smaller than those possible by flame. Today's geochemists are finding that they can gain valuable information out of very low limits of detection. Electrothermal atomic absorption spectrophotometry (or GFAA) allows for low limits of detection and can be seen to be a valuable aid to geochemical prospecting Analysis.

Jan 1, 1987

By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

With constantly rising energy costs it is ever more important that we look at ways of im- proving comminution efficiency both in terms of power consumed as well as capital costs required for purchasing and installing equipment. I intend to show that commonly used appli- cation criteria, which is presently accepted for designing crushing and screening plants, need drastic revision if it is to be used to accura- tely design, predict and refine performance in new and existing facilities. Unless we can calculate performance accurately, we cannot minimise capital investment and maximize Profitability.

Jan 1, 1978

By Singh DP, Singh TN

The present study attempts to critically review the pillar-design as required by Coal Mines Regulations of India vis-a-vis latest rockmechanics formulae. Equivalent material modelling was the approach adopted for testing the safety and stability of the pillar sizes predicted by various formulae. Two parameters, considered here for calculating pillar sizes was the stresses acting over the pillars and the strength of the pillars. Stresses acting on the pillars were calculated by the tributary area method. Based on the studies of Coates and Hustrulid, the stress obtained was reduced by 40 percent. For calculating the strength of the pillars, three formulae, namely Holland and Gaddy, Salamon and Munro and Central Mining Research Station, India, were used. The pillar widths were then determined by equating the product of recommended factor of safety and pillar stress with the pillar Strength.

Jan 1, 1992

Nickel laterite approximately 40% of the remainder caning deposits. ores are the source of the world's nickel with from sulphide ore Although laterite ores are near the surface and cheap to mine they require significantly more energy to treat than sulphide ores. The escalation of oil prices comiencing in 1973 meant that nickel laterite refineries using oil as an energy source were placed at distinct disadvantage relative to sulphide refineries or those with coal derived energy. The Queensland Nickel refinery commenced a construction programme; in 1980 to allow ore drying and power generation to be converted from oil to coal. Since late 1981 ore drying has been undertaken using heated air from two moving grate spreader grate stokers. The changeover from oil to coal drying proceeded without process disruptions. This paper discusses the plant changes required to allow the receipt of coal and the operating performance obtained from the coal fired air heaters.

Jan 1, 1987

Studying the ore textures in a discrete orebody is a novel approach to estimating liberation potential of the ore minerals present. As part of a PhD thesis, this project aims at classifying and quantifying the textures of the Hilton North orebodies, and at estimating their liberation characteristics.

Jan 1, 1993

The philosophy of computer control of grinding and flotation at ZC/NBHC is presented. The performance and reliability of the in- stalled systems are discussed.

Jan 1, 1978

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 E Jak

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

Jan 1, 2000

Indigenous brown coals, which provide a readily available primary energy source, have played a significant part in the industrial development of Victoria. The deposits located in the Latrobe Valley compare in extent with other major deposits of brown coal in the world. Smaller but valuable deposits occur at Stradbroke, Gelliondale, Anglesea and Bacchus Marsh. Extensive drilling, aided by geophysical surveys, and detailed analyses of coal samples, have enabled the extent and quality of these Tertiary deposits to be Defined.

Jan 1, 1979

By Jackson S

An investigation into different aspects of importance in the understanding of explosibility of hybrid mixtures of coal dust, air and gases potentially found within mine workings through a comprehensive laboratory program of explosibility tests was conducted. Plotting of test results revealed that conditions of potential explosibility could be described using two dimensional flammability limit surfaces- for coal dust/oxygen; methane/oxygen; and coal dust/methane mixtures. From these plots, the three dimensional flammability envelopes defining the explosibility of the coal dust/methane/oxygen mixtures can be defined and illustrated for a coal sample. The surfaces of the three dimensional envelope describe limits which separate inert mixtures of coal dust and methane at varying oxygen levels from those concentrations which are ignitable under defined conditions. It is considered appropriate to generalise that the geometric shapes of these limit regions are applicable to all type classifications of coal dust. There are practical applications of these results to the underground environment.The action of free radical initiators in the propagation of a methane gas explosion was examined for its applicability to the flammability of coal dust/gas/air mixtures. The oxides of nitrogen or NO x radicals have influence upon the lean limits of flammability of hybrid mixtures and this is illustrated by use of three dimensional coordinate geometry. Gases can be introduced to the underground environment through the exhaust gases of diesel equipment. It is concluded that radical species can substantially increase the flammability of gas and dust flames and as a consequence raise risk of mine atmosphere explosibility.

Jan 1, 1998

The Late Permian intermediate to silicic talc-alkaline Drake Volcanics of New England, N.S.W., consist largely of shallow marine, redeposited volcaniclastic rocks which host epithermal Ag-Au deposits. Pervasive hydro- thermal alteration is widespread. The 200-300 m Cataract River Member includes several sedimen- tation cycles composed of massive pumice brec- cias, overlain by laminated sandstones and siltstones, interbedded with marine, fossil- iferous mudstones. Two distinct groups of cla- sts exist within the volcaniclastic beds: 1. Lithics of predominantly intermediate compos- ition lavas that have undergone subaerial epi- clastic erosion and transportation; 2.Pumice, quartz and plagioclase crystals which have not been reworked by epiclastic processes. The lithic clasts were derived locally in a sub- aerial environment within the Drake Volcanics, and pumice and crystal fragments from contem- poraneous centres of silicic volcanism else- where in New England, N.S.W. The latter group of clasts was transported to Drake by Plinian airfall or rafting, and fell and was washed on- to emergent portions of the Drake Volcanics, where reworked locally derived fragments occ- urred. Cold state subaqueous mass-flows, prod- uced by slumping, resedimented the mixed vol- caniclastic detritus into the marine basin in a series of cyclic units with massive lower parts, and laminated upper zones. Modern ana- logs of the palaeogeographic setting in New England, N.S.W., in the Late Permian are pro- vided by the Taupo Zone, New Zealand, and sou- thern Kyushu, Japan.

Jan 1, 1987