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By R C. Morris

The channel iron deposits (CID) (Ramanaidou, Horwitz and Morris, 1991; Morris, Ramanaidou and Horwitz, 1993; Ramanaidou, Morris and Horwitz, 2003; Morris and Ramanaidou, 2007) are one of the two major iron ore types mined in the Hamersley Province. The CID provided around 41 per cent of the total of 268 Mt of iron ore mined from the Hamersley Province in 2006. The current CID resource is around seven billion tonnes. The CID deposits occupy numerous meandering palaeochannels in a mature surface that includes Precambrian rocks and ferruginous palaeogene valley fill. These palaeochannels are generally less than a kilometre but can range to several kilometres in width and from one metre to more than 100 m thick. The two currently mined CID areas are located:in the western Hamersley Province in the Robe palaeochannel, and in the east in the Yandi palaeochannel. These two major CID channels extend over 100 km to 150 km, with the Robe system up to 5 km wide. The granular ore facies typically contains ooids and lesser pisoids with haematite nuclei and goethite cortices, with abundant goethitised wood/charcoal fragments and goethitic peloids, minor clay and generally minimal porous goethitic matrix. Post deposition weathering is common and produced secondary facies.Ooids and pisoids were mostly derived from the stripping of a well- vegetated deep ferruginous surface. The peloids were derived both intraformationally from fragmentation and reworking of desiccated goethite-rich mud. Minute wood/charcoal fragments in the soil that were initially replaced by goethite and then dehydrated to haematite, formed nuclei for many ooids and pisoids. In addition, abundant, generally small (in situ by goethite within the consolidating CID. This profusion of fossil wood, both as ooids and pisoids nuclei and as discrete fragments as well as the local presence of kenomagnetite suggests major episodic wild fires in heavily vegetated catchments. The goethitic matrix was the result of chemically precipitated iron hydroxyoxides, resulting from leaching of iron-rich soils in an organic environment.

Jan 1, 2007

By Anderson J. M, Gillies A. D S, Jones N

There are a number of current theories in relation to methane migration and emission into workings following underground coal mining activity and some controversies do exist. Mining causes changes in the stress regimes in surrounding strata and results in fracturing. Permeability increases and methane flows into workings under a pressure gradient. The effects of stress on permeability depend on the physical properties of the coal and surrounding strata. Methane emission also depends on the original methane content and the proportion which will be liberated. There are several methods for determining in situ methane content and desorption characteristics of coal samples and several methane prediction methods but clearly more research is necessary to achieve an adequate predictive model.

Jan 1, 1992

By G W. Scott, R C. Johnson

Hypogene alteration zones have been described as a precursor to high-grade haematite deposits in Australia, Brazil and elsewhere. This alteration is described as being below or distal and is typically magnetite-carbonate-silicates reflecting Mg - Fe metasomatism. This paper describes, without genetic implication, the mineral zonation and possible structural control on mineralogic variation within the Tilden Mine, a concentrating grade haematite deposit in Michigan, USA. In contrast to the high-grade deposits, these variations are not peripheral to the orebodies but are the ore. The deposit occurs within the Negaunee Iron Formation, along the southern margin of the Paleoproterozoic Marquette Range Supergroup basin. The regional structure is a fault-bounded west plunging syncline within the crustal scale Great Lakes Tectonic Zone, which forms the boundary between Archean granite-greenstone and gneissic terranes. Local structure consists of second-order anticlines and synclines with variable northwest and southwest plunges. The interaction of sedimentation and diagenesis within growth fault controlled basins, along with a possible metamorphic and/or hydrothermal overprint has resulted in a complex series of ore types. For modelling purposes, the deposit is divided into geologic domains based on both lithology and metallurgical response in the laboratory and in the plant. Mineralogic variation is recognised within individual mineral grains; at blast pattern (10 - 15 m) and development drill hole (100 m) scales.

Jan 1, 2007

By Ohga K, Isobe T

Basing upon many and long practical experiences of gas drainage from coal seam and results investigations on the gas flow through in si-tu coal seam using tracer gases,it became clear that solid coal itself is hardly gas permeable or has extremely low gas permeability. Almost all of gas flows from a coal seam into boreholes through fracture net- works intersecting with them.Primary and secondary fractures in coal seams differ in their size and continuity from place to place according to differences of the coal strength and the stress conditions. A lot of gas can be drained through boreholes which intersect with many and/or wide fractures. A mathematical model for gas flow from a coal seam to a borehole through a discoidal fracture is proposed. From the numerical analyses,the apparent radius of the discoidal fracture in this model is shown to be a good indication of the gas drainage ratio. In addition to this,an atempt to make fractures around a borehole using high velocity water jet(ca.lmm dia.,300-700atm., 100-200 1/min.) is introduced.

Jan 1, 1982

By Eri G

Ok ledi Mining Limited underwent a major transition from radio based truck dispatching to computerized dispatching for its equip- ment fleet in October, 1996. Modular Mining's Computerized Dispatch System was selected based on reputation and superior customer support. Modular's dispatch system is a fleet management system that uses computer, data communication and global positioning sys- tem technology to produce automatic, optimized haul truck as- signments. Optimization is achieved by equally distributing trucks to shovels so that truck queuing and shovel idling times are mini- mized. Computer illiterate mine operations personnel had to overcome a rather steep learning curve to use the high technology equipment. fortunately the system was able to be configured to use bitmap

Jan 1, 1997

The metallogenic belts of the Central Andes (iron, porphyry copper, polymetallic and tin) are genetically related to an eastward migrating magmatic arc. The polymetallic belt of the Bolivian Altiplano formed during Miocene arc broadening and lies in a critical position for understanding the genesis of this zonation. It is penecontemporaneous with parts of the copper and tin belts, and shares many characteristics with them. The differences between the belts result from contrasting volcanic and feeder stock geometry, depth of erosion and country rocks, and are not due to variations in magma chemistry, age or Benioff Zone depth. Polymetallic mineralisation in the Altiplano is epithermal in style and mostly related to flow-dome volcanism. The intermontane basinal setting precludes deep erosion to expose the epizonal feeder stocks and predicted porphyry copper mineralisation. In contrast, erosion of the less abundant stratovolcanoes of the Altiplano-Puna and Pampean Massif may expose contemporaneous Miocene porphyry copper mineralisation in subvolcanic stocks. The tin belt is coincident with the Paleozoic fold belt of the Eastern Cordillera. The occurrence of minor tin in Altiplano epithermal deposits hosted by Paleozoic sediments, and the persistence of tin mineralisation in the tin belt over 350Ma, suggests that Paleozoic sediments are the source of the tin.

Jan 1, 1987

By Weining L

In-situ experiments were performed in a tunnel built in loess soil with the displace- ment components of the tunnel lining and the acceleration components of the tracks measured during the passing of trains. The measured parameters were then studied by the spectral method. As a result, the dynamic forces of trains was simulated numerically and a deter- ministic dynamic nonlinear analysis was carried out by means of finite element method. The results obtained by two different approaches were in fair coincidence. Results of the study indicate, that the low and medium frequency components of the dynamic train loading would be crucial for the dynamic responses of the tunnel lining and surrounding mass, and their effects would increase with the speed of passing trains within a certain range.

Jan 1, 1987

A standard practice of auditing mill designs has developed in the mining industry. The purported aim of this task is to ensure that the mill being offered conforms to the design specification, thus reducing the purchaserÆs risk. However, careful examination of the auditing methods used in the past shows that this is not the case. In some cases, what auditors have been providing is effectively a quality assurance check of the input data, not a full independent audit of the vendorÆs design. It will be shown that these past auditing methods have contributed to the stagnation of mill specification development. This lack of specification improvement combined with the current trend towards increased allowable fatigue stress ranges can result in an increase in risk for the purchaser.

Jan 1, 2002

By M Titley, E Maidens

Many gold deposits were mineralised by fluids and processes that also altered the host rocks. This alteration may often be a useful visual aid that distinguishes barren, low-grade from high-grade regions in a rock mass. Alteration intensity is commonly used in gold deposits as a visual tool, along with face sampling or grade control support, to define oreblocks and guide excavation in underground and open pit mining. However, alteration is not often used at the resource estimation stage. Mineralised lodes are usually defined by geologists using a ægeo-grade envelopeÆ, where a number of constraints are considered, including an (arbitrary) cut-off grade; the ænaturalÆ grade break between high- and low-grades; and geological features including structural, lithological or alteration continuity. The geo-grade envelope is usually thought to satisfy the requirements of stationarity for grade estimation, and is considered a single domain. This paper examines a modelling technique combining gold grade and alteration, applied to the Wallaby deposit in Western Australia, to imbue a greater level of detail to the grade estimation in a region tested by relatively sparse drilling. This was achieved by utilising the correlation of gold grade and alteration, along with the spatial characteristics of the alteration, when estimating grades within a number of lodes. The alteration-driven estimation was utilised in conjunction with an unfolding approach, and the use of probability estimates, to overcome geometric data constraints. This technique allows greater control and most likely provides a more reliable estimate of the mineable resources than a global grade cut-off when visual control is to be a major vector in grade control.

Jan 1, 2003

The Northern Mariana archipelago in the W.Pacific forms a classic intra-oceanic island arc system far from the influences of continental crust. As such it offers an ideal location in which to study many of the problems of subduction-related volcanism. Radiogenic (Sr, Pb, Nd and Hf) and stable (0, S and H) isotope systems have been applied to the question of the possible involvement of components from the subducting slab in arc magmagenesis. The results contrast with earlier studies based upon limited sample suites and suggest that fluids, derived from the slab and enriched in mobile elements, substantially modify the composition of the mantle wedge and contribute to the characteristic geochemistry of arc magmas. Trace element data, including the occurrence of negative Ce-anomalies in the lavas seem consistent with this conclusion. Major and trace element variations within the arc lavas can be modelled in terms of crystal fractionation of a gabbroic mineral assemblage and mixing calculations indicate that this has the approximate composition of PLAG:CPX:MAG:OLIV = 60:25:10:5. This observation is compatible with the widespread occurrence of gabbroic nodules in lavas throughout the arc. Consideration of Rare Earth Element and phenocryst data leads to the conclusion that many of the more basic lavas may be the products of cumulus enrichment. The results of this study constitute a model for magmatic processes occurring in simple island arc systems, and may be generally applicable to other, more complex settings. The recognition of a return flux of material with 'continental' affinity to the mantle, via sediments on the subducting slab, also places strong constraints on geochemical models of crust-mantle evolution.

Jan 1, 1987

The mineralogy, maero- and micro-textures of Thackaringa ore are simple and have many counterparts among base metal-quartz-siderite vein type deposits elsewhere.The ore consists predominantly of galena, sphalerlte, chalcopyrite, tetrahedrite, and arsenopyrite in a quartz and siderite gangue. Silver minerals, as such, appear to be lacking and silver values are no higher than in other sulphide ores of this type. These features contrast very markedly with those of the A.B.H. Consols Lode which appears to have emanated from the north end of the Broken Hill Main Lode Horizon during high grade regional metamorphism. The Consols Lode has been regarded as of Thackaringa type, and both are regarded as possibly arising from the remobilization of Main Lode Horizon ore. Whilst this may yet prove to be so it appears that the marked differences in mineral composition between the Consols and the Thackaringa types, would require somewhat different modes of regeneration.Thackaringa ore, as well as A.B.H. Consols ore, on this basis, would necessitate the development of a metahydrothermal ore fluid to account for their present apparently hydrothermal (or pseudo-hydrothermal) constitution...

Jan 1, 1967

By Orrock G, McKee DJ

Mathematical models of autogenous and semi-autogenous grinding mills have now reached a stage of development where they can be usefully applied to practical problems. In particular, the models are suitable for inclusion in simulations of grinding circuits to study the effects of cir- cuit changes, variations in ore type and changes in throughput. The paper describes a simulation study of the Elura grinding circuit where the empha- sis was on investigating methods of reducing product size from an autogenous mill-ball mill grinding circuit.

Jan 1, 1988

The goal of the Bureau of Mines, U. S. De- partment of the Interior, diesel engine research program is to reduce exhaust emissions and mini- mize the risk of fires and explosions caused by the use of diesel-powered equipment in under- ground mines. Significant results of research conducted during the last 5 years are briefly described, with references to published reports on specific topics. Topics covered here include brief discussions of a newly completed diesel research laboratory, the effects of a fuel addi- tive on diesel exhaust particulate matter, the effect of diesel engine maintenance on emis- sions, a diesel particulate filter for equipment used in underground metal and nonmetal, and coal mines, and lastly, the prototype hydrogen- powered mine vehicle. These research accomplishments could favor- ably affect the mining industry by reducing the health and safety hazards associated with the use of diesel-powered equipment in underground Mines.

Jan 1, 1988

Grade control is an important factor in the on-going success of a mining operation. Grade control criteria will vary depending on the commodity being mined. Financial considerations determine the actual grade control criteria at any one mine site. Mining and metallurgical capital and operating costs are ultimately used in ascertaining cut-off grades employed in grade control. The metallurgical characteristics of the ore, and ultimately the equipment selection and design of the plant, are based on samples provided by the exploration geologist. Ore variability is an important factor in designing the process plant. Ore variations, outside of those catered for in the design, as well as large ore changes on a daily basis, will impact on the metallurgical performance, and hence the economics of a mining operation. Therefore good liaison between the grade control geologist and metallurgist will undoubtedly lead to a more consistent, and more profitable mining operation.

Jan 1, 1993

By M Thomas, S Lambert

The Tugun Bypass Tunnel in Gold Coast, Australia was constructed using diaphragm walls with the top-down cut-and-cover method to allow simultaneous construction of an airport runway extension above the tunnel, whilst excavation of the tunnel continued underneath. The tunnel was built in an environment of high groundwater table and deep deposits of alluvial and estuarine soils with the toes of the walls founded in soil deposits. There was a potential risk for differential settlements to occur between the diaphragm wall panels, caused by the runway fill placed over the tunnel roof during excavation. Dewatering within the diaphragm walls was required to facilitate the construction of the tunnel. The tunnel was also built in an area where environmental considerations were of great importance. Three-dimensional numerical modelling was undertaken to predict the differential settlements of the tunnel with considerations of varying subsurface profile, staged excavation and dewatering, non- uniform surface loading and complex soil-structure interaction. Field instrumentation and monitoring was implemented to confirm numerical predictions.  

Jan 1, 2008

By Scherbatsky VB, zon BM, Babushkin NM, Kitaev BI, Shabel&apos

The structure and hydrodynamics of the raceway zone of a blast furnace was studied on a cold model representing a sector containing two tuyeres. The model differed from the usual in that it was prov- ided with continuous flow of the coke layer at pre- determined rates, had provision for changing the tuyere parameters (diameter, protrusion, inclinat- ion) and irrigation of the layer with liquid. A combination probe was developed which per- mitted simultaneous measurement of the pressure field both across the area and through the height of the layer as well as determining the topography of the raceway. The velocity fields in the layer were measured with a specially made impulse thermo- anemometer. The determining criteria of the model were taken as the relationships between the energy of the blast and the particles, the dimensions of the raceway and the cross-section of the tuyere. The model established the effects of the tuy- ere structural parameters, blast parameters and amount of liquid products of smelting on the con- figuration of the raceway, the structure of the layer, pressure and velocity fields in the vicinity of the tuyeres and in the vertical direction through the layer. The properties of the raceway formation and the structure of the layer in motion have been clarified.

Jan 1, 1981

The Government Mining Engineer of South Africa has decided to legislate that Self Contained Self Rescuers (S.C.S.R.) become a mandatory piece of equipment for all those persons proceeding underground. It is envisaged that: * employees in underground coal mines will be fully equipped with S.C.S.R.s during 1988; * those persons employed in gold mines during 1988/89; and * personnel in all other mines by the end of 1990. It is the intention of this paper to discuss the introduction of these auxiliary life support systems, and to give an update on current market developments.

Jan 1, 1988

The Kanowna Belle deposit was discovered in 1990 following encouraging assays from soil sampling and RAB drilling. At the end of September 1993, diamond drilling had been completed to a vertical depth of 1,000 metres and a resource of 22 million tonnes grading 5.73 grams of gold per tonne containing a million ounces of gold had been defined. The deposit remains open at depth. Pre-production mining for the open pit began in November 1992, construction of the oxide treatment plant began in January 1993 and the first gold was poured in September 1993. Sulphide ore roasting commenced in December 1994 and the underground mine development commenced in July 1995. The Kanowna Belle project is owned by the Golden Valley Joint Venture (GVJV), an unincorporated joint venture with equal shareholdings between North Gold (W.A.) Ltd and Delta Gold N.L. North Gold are the managers of the development and operations and Delta Gold are the managers of exploration throughout the GVJV tenements.

Jan 1, 1990

By V K. Singh, G Sural

The problem of spontaneous heating/fire is very common in coal mines all over the world. The coal industry faces many problems day by day due to the occurrence of spontaneous heating in the open pit coal mines. Presently, about 70 per cent of total coal production in Indian mines is being carried out by open pit mining. Fire in coal, particularly in open pit mines not only causes irreparable loss of natural wealth but also damages the surface structures and pollutes the environment. It is well known that 75 per cent of the fires occur due to the spontaneous combustion of coal. Spontaneous heating is a very common occurrence in coal mines and is a major factor contributing to mine fire. The liability of coal to spontaneous heating causes many serious problems before, during and after mining. In opencast mines, coal immediately oxidises and catches fire due to the intrinsic characteristics of coal, such as low rank, high moisture, high volatile matter, presence of sulfur in the form of pyrites, low crossing point temperature (CPT) and ignition point temperature (IPT) value and less incubation period. In opencast mines, when the coal benches are left idle for a longer time, heat accumulation takes place in favourable conditions and sometimes leads to fire. The purpose of this paper is to present the different successful case studies regarding the safety management of open pit coal mines from occurrences of spontaneous heating/fire.

Jan 1, 2007

The coastline is. an incomparable stretch of sea coast known as Ninety Mile Beach. Two gas pipelines and two oil pipelines carrying hydrocarbons from thb'Bass Strait fields to the markets of Australia cross this beach. They cannot be seen as they are laid in trenching stretch- ing many miles out to sea and the beach was restored to its natural state. Even where the dunes were disturbed, suitable grass was sown thus consolidating the sand and preventing erosion. Ninety Mile Beach is but one of the many key.wildlife and recreational areas that our operations must be concerned with. Others include Westernport and Corner Inlet, but the one discussed in this paper in particular is the platform area of the Bass Strait itself. Never was the old adage "an ounce of prevention is worth a pound of cure" more meaningful than in offshore oil production. All are well aware of some of the events of the past several years that resulted in large and costly oil spills. Far less is known, seen or publicised about the measures and developments that are undertaken to ensure that such events do not occur. We also have well developed plans for response in the event of an emergency situation, which can be initiated with great rapidity. Our responsibility is to ensure that with the best of engineering technology and operating procedures, spills do not occur.

Jan 1, 1971