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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

Distillation of the large and growing greenhouse literature indicates that: ò Global warming has occurred over the past century or more; ò Build-up of CO2 (and lesser greenhouse gases) in the atmosphere is a fact; ò This build-up is likely to cause further global warming. It does not appear possible to conclude that the observed C02 build up and observed global warming are linked; nor is it yet possible to forecast global or regional climate variation with conviction. The dominant greenhouse gas is C02 with about half the warming potential of those gases emitted by man's activities; and about 80% of anthropogenic C02 emissions are from the burning of fossil fuels. Fossil-fuel C02 emissions arg divided about equally between the developed countries of OECD and the rest of the world. However C02 output growth over the past decade was about 4% for OECD and some 40% elsewhere. Population growth and pressure for better living standards will ensure continued higher growth outside OECD. Uncertainty about the impact of increasing C02 emissions on climate, and the long lead-times involved in limiting the increase in atmospheric C02 concentrations, are good reasons for taking action now. Australia accounts for about 275 million tonnes a year or just over 1% of the CO2 emitted from the world's consumption of fossil fuels, and the fight to control global emissions will be won or lost elsewhere. Australia's participation will be by wise conselt and by example. In view of the uncertainties involved, it appears premature to take actions that might place an additional financial burden on our hard-pressed country. However, much can be done now that makes good economic sense and has the added benefit of limiting the growth in Australia's CO2 emissions. Natural gas emits less C02 per unit of energy when burned than either coal or oil. Furthermore, new gas-fired power stations utilise energy at considerably higher efficiency than is the case today with coal or oil. Because of much lower capital costs, there is a compelling economic case for permitting natural gas to compete freely with coal in the Australian power generation market.

Jan 1, 1989

A combination of highly structured, fissile stope hangingwalls and high ground stresses have caused difficult mining conditions in the Main Lode Deeps at Lancefield Gold Mine. Cyclic reviews of ground support and stoping techniques, coupled with geotechnical investigations, and the application of numerical modelling has led to the successful management of stoping operations.

Jan 1, 1995

By Williams J. D

Magnetite has been used in coal processing for many years and it is likely that its use will continue well into the twenty first Century. While magnetite is only a minor cost component in coal processing, the use of processed magnetite in dense medium separation is essential to provide the split of quality coal products which the markets of today demand. The occurrence of magnetite in Australia is relatively abundant, but a combination of its iron content, magnetic properties, quality and proximity to the coal processing plants is essential to provide a low cost product for use in the Coal Industry. The demand for more splitting of coal in coal processing may require more grades of magnetite, particularly as a finer grade lower specific gravity medium to separate the finer quality low ash coals.

Jan 1, 1991

By Y Chung, B Choi, H Lee

Numerous studies have explored refractory corrosion in the presence of slag and/or metal, utilising the Finger Rotating Test (FRT). Recent experimental results revealed that corrosion initially increased with rising rotation velocity but was then suppressed above a critical rotating speed, under conditions involving a two-liquid solution of slag and molten steel. This phenomenon indicated that the liquid/liquid interface movement occurred during spindle rotor. However, understanding of the phenomenon, known as the rod climbing effect, remains inadequate in the case involving slag, molten steel and refractories. To gain deeper insights, a simulation experiment was conducted on the phenomenon using silicon oil/water and the phenomenon was analysed using computerised simulation software (Ansys Fluent). Experimental modelling demonstrated that interfacial movement occurs even at low rotation velocity, as low as 200 rev/min, when the viscosity of silicone oil is at 100 cP. Computational analysis utilising the Volume of Fluid (VOF) method and a realisable k-ε turbulence model elucidated that interface elevation during rotor rotation arises due to viscosity disparities between the two fluids. Furthermore, this movement is more pronounced when the viscosity difference is lower. Additionally, the study findings suggest that higher density differences between two liquids suppress the phenomenon of interface movement.

Jun 19, 2024

Investigations of the Mineragraphic Section; Commonwealth Scientific and Industrial Research Organisation, have included most of the known stannite-bearing ores in Australia, and have revealed several new occurrences of this relatively uncommon mineral. They provide information about its paragenesis, and its possible effect on tin recovery, that may be of general interest.Several of the investigations used in the preparation of this paper, were made in the first instance by pr. F. L. Stillwell or in collaboration with him.CASSITERITE-SULPHIDE ORES IN NORTH-WEST- TASMANIA Stannite is a minor component of most of the cassiterite sulphide ores of north-western Tasmania. These include the orebodies of Mount Bischoff, the Cleveland mine, Moina, the Stanley River district, Renison Bell, and the Heemskirk-Zeehan district, and form a well defined metallogenetic provence which is related to the Devonian granites of this part of Tasmania.In these ores mineralisation began. with deposition of cassiterite, a little wolfram, and quartz, topaz and tourmaline. With falling temperature, deposition of cassiterite ceased and arsenopy-rite, pyrite, and especially pyrrhotite, formed in abundance, tending to give massive sulphide ore. A little chalcopyrite; stannite, sphalerite and native bismuth accompanied the pyrrhotite. Deposition of quartz ceased after the pyrrhotite, was formed, and the later-formed nonsulphide gangue consists chiefly of carbonates and fluorite. With, the advent of the carbonates the pyrrhotite was altered to fine-gained intergrowths of marcasite and pyrite. Excess iron from the pyrrhotite entered the intergrown carbonate, or was precipitated as magnetite. Some solution of the cassiterite occurred at this stage, the tin being redeposited chiefly as stimnite replacement rims around the residual cassitellrite grains. Varying, but small, amounts of sphalerite, galena, tetrahedrite and silver minerals were depoSited at this stage, bringing the mineralisation to a...

Jan 1, 1951

The Escondida Porphyry Copper Deposit, located in Chile's II Region 160 Km to the southeast of the city of Antofagasta, is currently owned by Minera Escondida Limitada, a company comprising The Broken Hill Proprietary (57.5%), Rio Tinto Zinc (30%) a group of Japanese companies represented by Mitsubishi Corporation (10%), and the International Financing Corporation of the World Bank (2.5%) (Fig.l)By 1983, most of the reconnaissance drilling was completed and prefeasibility studies were regularly updated as new drilling results were reported and project concepts re-evaluated (Fig.2). In October 1982 the project was transferred from Exploration Management to Operations. By the end of 1984 project pre-development activities, including inpit development drilling, geological exploration, water resource definition, an underground bulk sampling program and the initial project feasibility report, were completed.

Jan 1, 1990

The accurate calculation of ore reserves is one of the most important functions under- taken at a potential or operating mine. In recent years there has been a trend towards recommending more and more complex techniques for the calculation of reserves. However these are not always necessary and many improvements could be made by the use of all potential data and a heavier geological input. An ore reserve should be the result of geological not mathe- matical or engineering reasoning. All ore reserve estimates are wrong and the important thing is to.recognise why they-are wrong and to take action to minimize the errors. Geostatistics and other complex mathematical techniques may appear to answer all our needs for ore reserve accuracy but there are many drawbacks, not least of which is the communi- cation gap which may develop between the operator and both management and production Personnel.

Jan 1, 1979

Conflicting claims and views on the priming of ammonium nitrate/fuel oil (ANFO) are reviewed; certain fallacies and misconceptions are rectified. Optimum priming systems for a range of blasthole conditions are indicated. Moves towards optimum priming lead to reductions in the combined cost of drilling, blasting and handling the material. With shallow blastholes, two-point priming is rarely warranted. Best blasting results from single priming are usually obtained when the primer is located near, but not at, the bottom of the blasthole. As blast- hole depth increases, two-point priming becomes more reliable and effective than single priming. For two-point priming, primers should be located such that detonation waves in the ANFO collide at grade level or, if preferred, within a hard band in the burden. Where blastholes are very deep and/or strata variations can be appreciable, three or more spaced primers are often justified. The effectiveness of a primer varies with its detonation pressure, diameter and length. Primer properties influence the velocity of detonation (VOD) near the primer, but do not affect the final (steady-state) VOD in the ANFO. Some primers cause 'run-up' (i.e. lower than steady-state) velocities whereas others cause

Jan 1, 1974

Utah's Blackwater mine began operations in 1967. The four CQCA mines controlled by Utah followed over the period 1971 to 1979. Project feasibility studies for all these were based on open cut mining to overburden depths of 60 metres, with typical project lives of 12 to 16 years, depending on reserves Further studies, initiated after the mines had started, showed that continuation of open cut mining beyond the 60 metre highwall was viable. In 1973, the Deep Stripping Project (DSP) was launched to define the scope for stripping deeper, to determine what the additional equipment needs might be, and to pu forward proposals for a full scale trial system. The project commenced at grass roots with a literature survey, proceeded through a sequence of equipment evaluation, specification, design and manufacture to the commissioning of the Goonyella BWE system. Studies are continuing to assess the future deep stripping requirements for all Utah's Bowen Basin mines.

Jan 1, 1983

Instantaneous outbursts of coal and gas have occurred in Australia in the Sydney Coal Basin since 1895 and in the Bowen Coal Basin since 1954. The largest has been about 500 tonnes of coal and so their magnitude and character have not approached those experienced in some other countries. The occurrence of CO2 with some Australian cases provides some similarity with the worst affected areas in France and Poland.The proneness of seams depends on coal rank and seam gas composition, among other factors. The proneness of places depends on depth, structure, intrusion, tectonism and other factors affecting the geometric, physical and chemical uniformity as well as details of mining. As a phenomenon due to gas and stress, prevention can be achieved by relief of high gas and/or stress condition. Alternatively, controls can be applied to render mining safe for personnel. Unfortunately day-to-day prediction is not widely and reliably achieved to allow selective use of prevention or control. The initial rate of desorption is the most promising day-to-day indicator.Various researches include gas conditions and parameters, stress and failure conditions and parameters, coal variables and geological variables in relation to prediction, prevention and control. Some assistance in research may derive from study of analogous phenomena of instantaneous outbursts of salt and other rocks and gas. It is concluded that in the Sydney and Bowen Basins, any coals with less than 30 per cent Volatile Matter (VM) ash free dry (afd) at depths over 200 m could be prone. Proneness increases with depth, with lower volatile content, with geological disturbance including faulting, intrusion and recent tectonics, with increased CO2 in seam gas, with narrow work and with other factors. Much more research is needed.Unfortunately outbursts are needed too, to provide the research with realistic data. With the problems of mechanism and prediction still being unsolved much research remains to be done. No present aspect of research is satisfactorily resolved.

Jan 1, 1983

By L Whitbourn, K Yang, P C, E Ramanaidou

The potential of hyperspectral mineral mapping within a mine environment is demonstrated. Central to this capability has been the development of portable or vehicle-mounted, hyperspectral mine face-mapping systems. Data from these systems were used to detect subtle mineralogical variations and map their distribution across rock faces in a fashion that previously was not possible. In one study, the data usability was enhanced by ædrapingÆ the mineralogical determinations over a three-dimensional æmodelÆ of the rock-face. The eventual melding of the spectral mine face-mapping and three-dimensional spatial technologies will result in a new generation of mineralogical and structural information becoming available to mine geologists, engineers and metallurgists. Specific uses for spectrally-derived, mineral mapping data sets could include:ore grade mapping systems based on either direct detection of ore minerals themselves (eg iron and nickel oxides), or mineralogies that may be used as surrogates for ore-grade information (via various alteration minerals) after a suitable orientation survey; detecting mineralogies that have a deleterious effect on milling, metallurgical processing or have occupational health implications (talc, swelling clays, carbonates, asbestos, etc); selective mining and blending by collecting, processing and displaying such mineralogical images in near real-time to monitor ore grade and quality, and allow the separation of ore from waste during loading operations at the mine face; a mineral detection and mapping capability to assist in structural and geotechnical mine planning applications; and an enhanced geological detection and mapping capability for ore mineral species or alteration mineralogies that may be used to vector further mineralisation, update the existing mine ore model, or provide input to assist in the control of autonomous mining equipment. Within the Woodlawn open pit, Fe- and Mg-chlorites and phengitic- micas associated with sulfide mineralisation were detected and mapped. Subsequent studies using a second generation face-mapping system demonstrated the direct detection of ore-grade materials for iron-ore and nickel laterite mining activities. Satisfactory and meaningful results were extracted from data that were collected under a variety of challenging conditions. However, these non-ideal climatic and operational conditions would be expected under most operational situations in a mine environment. Development of a system using artificial illumination, permitting night-time (and eventually underground) operation and elimination of atmospheric absorption effects is underway.

Jan 1, 2006

By Edwards A. B

Yampi Sound is a small channel in the Buccaneer Archapelago (latitude 16° 10' S.; longitude 123° 40' E.), on the northern coast of Western Australia (Fig. 1), about 90 miles north of Derby, and 200 miles north-east of Broome.The iron ore deposits of Yampi Sound occur on an approximately S.E.-N.W. trending belt of islands which form the northern boundary of the Sound (Fig. 2). From east to west they are Koolan Island, Tarrant Island, Usborne Island, Cockatoo Island, Irvine Island, Kathleen Island, Flora Island, and Bathurst Island. To the south of the Sound lie Margaret Island, which is separated from the mainland by a channel only 60 ft. wide, Dorothy Island, and Gibbings Island. Some of the channels between the...

Jan 1, 1938

Detailed underground mine design and optimisation studies undertaken by the author over the past few years have clearly demonstrated that additional value can be created by varying the cut-off grade (COG) spatially throughout a deposit as well as over time. This additional value can be particularly significant for marginal operations. This paper, by way of worked examples, illustrates the conceptual and practical considerations of applying a differential cut-off policy for an underground mine to both maximise value and manage risks associated with production and metal price volatility. Consideration is given to both the design stage of a new mine and to the strategic and practical application of a differential cut-off policy in an operating mine.

Jan 1, 2005

Lateritic nickel ore occurs as a supergene or residual deposit as a result of the tropical weathering of underlying ultramafic rocks. The mineralisation may be as hydrated Ni-Mg silicates, like garnierite (silicate ore); or as hydrated Ni-Fe oxide (oxide) ore. Non-sulphide ore represents only 30% of the tonnage mined, but represents 85% of the total world's nickel reserves. A typical lateritic profile consists of 4 zones above the unweathered ultramafic parent rock: Zone 1: the "upper laterite" which is dark red-brown, porous and concentrically structured. It contains 0.2 to 0.8% Ni, 48.0 to 72.0% Fe, and 0 to 9.5% MgO. It is often capped by a ferricrete crust. Zone 2: the "middle laterite", which is red-brown to light brown and more porous than the above zone. It contains 0.8 to 1.5% Ni, 42.0 to 48.0% Fe and 0.5 to 6.0% MgO. Zone 3: the "basal laterite" which is yellow-brown to yellow-orange,

Jan 1, 1974

By D S. Stewart, K W. Keskimaki

The Henderson Mine has been utilising a continuous panel caving method to extract molybdenum ore since starting operation in 1976. In the past three decades since the mine was designed, many changes have taken place in underground technology as well as the general nature of the mining business. The impacts of larger scale underground equipment and automation are significant at Henderson and continue to reshape the nature of the enterprise. During the first years of operation in the 1970s, Henderson required almost 2000 employees to achieve full production, today only about 400 people are required to fully utilise the plantÆs capacity. The most recent change to the facility is the conversion from a rail haulage system to an underground crushing and conveying system that transports ore 25 km to the Henderson mill site. This change has required the introduction of large, rubber tired haulage trucks underground and the mining methods necessary to develop the large openings demanded by the trucks and underground crusher. The development of the underground crusher is also the first step to mining the final bottom horizon of the orebody. Along with this move comes an opportunity to almost triple the effectiveness of the mining effort, through higher draw columns and wider draw bell spacing. This final advancement to a totally trackless mine has positioned Henderson well for safe and efficient operation as it enters the 21st century.

Jan 1, 2000

By C Ward, U Mueller

Compositional geostatistics is an approach developed to ensure that the constant sum constraint induced by geochemical iron ore analysis is respected in estimation and simulation. Jack-knifing and cross-validation were used within this framework to compare the results from ordinary cokriging of the additive log ratio (alr) variables with those from conventional ordinary cokriging. Two methods were used to back-transform the alr estimates: the crude additive generalised logistic back transformation and numerical integration via Gauss-Hermite quadrature. Previous work on a blasthole data set from a Yilgarn iron ore mine showed promising results, with the Gauss-Hermite quadrature method returning results comparable to ordinary cokriging from the point of view of bias, but superior in that the constant sum constraint imposed by geochemistry of the data was honoured. Other practitioners have noted that the linear interpolation of non-linear log ratio transformations will result in biased results, and that this bias can be masked in a (grade control) setting where the spatial density is high. To test this assertion, the methodology has been extended to successively lower spatial density data sets. The results and applicability to routine iron estimation are discussed.CITATION:Ward, C and Mueller, U, 2013. Compositions, log ratios and bias - from grade control to resource definition, in Proceedings Iron Ore 2013 , pp 313-320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The structural pattern of Victoria shows the presence of EW, NW, NE as well as the more readily recognised NNW factors commonly associated with the goldfields. ENE and WNW trends are also present. This structural lattice affects all rocks of the State. Landsat imagery shows that the EW, NW and NE structural elements are closely related spatially to the distribution of Palaeozoic igneous intrusives, Cainozoic volcanic vents as well as all historically important gold mines. It is suggested that the EW, NW and NE structural grid visible on landsat imagery is a reflection of the structure of a mid-crustal layer situated between 3.5 and 17 kms below the surface. The points of intersection of the structural elements of the mid-crustal layer offer most favourable loci for the escape of energy in the form of heat. The correlation between the distribution of igneous plutons, volcanic vents and centres of mineralisation, all reliant on high levels of energy for their formation, indicates the stability of the structures of the mid-crustal layer since early Palaeozoic times. The deep level crustal structures are believed to be, related to the release of stresses placed on the crust since early Palaeozoic times by the rotation of the Earth. A geological model that accommodates the presence of a mid-crustal layer as well as the complexities of the recognised orogenic cycles of southeast Australia is suggested. All 1 000 kg Au reef and deep lead mines fall within 1.5 and 2.5 km respectively of strong linears associated intimately with plutons and volcanic vents. Future exploration of the State is more likely to meet with success if it too is confined to the evaluation of these and similar linears. The mode of mineralisation of any one centre will depend upon the temperature, pressure and geochemical gradients operating on the migrating mineralising fluids as well as the structures in the host rocks. These factors are likely to have varied considerably from one centre of mineralisation to the next and consistency of mineral isation form and depth should not be expected along the length of any single Linear.

Jan 1, 1986

ADDRESS BY THE PRESIDENT OF THE INSTITUTE (MR. C. H. MARTIN) IN PRESENTING THE CERTIF1CATE TO SIR GEORGE FISHER, C.M.G.Members of The Institute, distinguished guests, of which there are many, ladies and gentlemen, you are welcome.And might I add a special welcome to Lady Mawby and Lady Fisher and to Sir George's only son Peter, who with his wife, Betty and one of Sir George's three daughters, Helen, are present this evening, and also to Sir Maurice's son, Colin, and Colin's wife, Jay, also in our company.The family presence must surely be a great source of pleasure and satisfaction to all those so intimately concerned.It is hardly. necessary for me to state the sole and only rC'l.son for our presence here tonight, which is to conJer on Sir George Fisher and Sir Maurice Mawby Honorary Membership of The Australasian Institute of Mining and Metallurgy, and at the same time to acknowledge two people who have rendered great service to the mining industry albeit tinged with sadness to all of us in the knowledge that from now on their influence may diminish.

Jan 1, 1976

By F Clark, M Erickson, J Biggam

Unraveling geological complexity and understanding geological risk are critical components of the challenge that face any mining or exploration venture. This understanding is essential to the successful selection of mineralised domains on which grade estimation relies, so knowledge of the geological characteristics of the mineralised domains is vitally important. æNuggetyÆ mineralisation introduces a higher level of risk and geological observation and intuition may be the only option to ensure that opportunities are realised and ore/waste characterisation is undertaken successfully. Mineralisation at the world class Sunrise Dam gold mine contains a significant coarse gold component, which has necessitated the development of a systematic visual approach to decision making that enables geological staff to determine the potential gold grade in the absence of assay results, and in those instances when assay results appear implausible. The development of the Mineralisation (MZ) Code at Sunrise Dam has assisted in reducing the risk of misclassifying ore as waste and enabled geological control to prevail with confidence where complexity and ambiguity existed.

Jan 1, 2009