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By F. E. Joyce

This paper describes the development of a process for producing manganese and iron pellet concentrates from low-grade manganiferous iron ores of the Cuyuna range by a two-stage sulfatization-reduction roast. First, the manganese minerals (7.5 percent manganese) were converted to water-soluble manganese sulfate by roasting in sulfur oxide gases at 700° C, then, the hematitic iron minerals (31 percent iron) in the hot sulfatized are were reduced to magnetite with simulated reformed natural gas in the temperature range of 350° to 425° C. Batch tests were made in a 3-inch-ID by 6-inch-long, gas-heated, stainless steel retort, and continuous countercurrent experiments were performed in a 2-inch-ID by 10-foot-long, electrically heated shaft furnace. Manganese sulfate was removed from the roasted product by leaching with water, and over 90 percent of the manganese was recovered in an oxide product (65 percent manganese) obtained by precipitation, drying, and thelmal decomposition of the sulfate. An iron oxide concentrate (60 percent iron) with an iron recovery of 75 percent was obtained from the water-insoluble residue by magnetic separation.

Jan 1, 1973

By Patrick Bermingham

The advancement of hydraulic impact hammers has followed the general advancement of hydraulics. The construction industry has been revolutionized by the application of hydraulics in excavators, cranes and, of course, in the hydraulic vibratory driver/extractor, which has become a standard tool. The innate ability to move a large mass with a very small displaced volume has given hydraulic power the advantage over previous power mediums. Recent development of more specialized and complex seal configurations and compounds has greatly improved the reliability and permitted the use of higher pressures in hydraulic systems.

Jan 1, 1987

By G. van Aswegen

The geometry and morphology of a set of low-angle fractures around a stope in a deep Witwatersrand gold mine are explained in terms of extension fractures forming under variable conditions of stress. Primary extension fractures (E1) form some distance ahead of an advancing stope along the s1, s2 plane. With stope advance, a couple of these fractures end up in a stress regime conducive to transpressional shear and a secondary set of extension fractures(E2) is formed at a high angle to the primary fractures. i.e. at a low angle to the stope. As the E2 fractures are undermined, they migrate into a stress regime of transtensional shear and a third set of extension fractures (E3) may develop between E2 fractures. These have sigmoidal shapes, being parallel to the E2 fractures at the E2 discontinuity where s3 is negative, and curved through the un-fractured rock between E2 fractures where s3 is positive at the instant of fracturing. The fractures all display fractographic features characteristic of dynamic extension failure with striae indicative of the direction of rupture propagation and the local, instantaneous orientation of s1.

Jan 1, 2012

By Paul Staples, Chris Morley

"The development of the Cerro Verde, Amplats Mogalakwena and Boddington projects over the last few years has helped to establish the use of high pressure grinding rolls (HPGR) in comminution circuit designs in large-scale hard-rock applications. The increasing acceptance of this innovative and sometimes controversial technology has had the natural effect of prompting many other new projects to examine HPGR as an alternative to the established, usually SAG-based, comminution circuit design approach.At the current stage of development of the technology, HPGR-based circuit capital costs are generally higher than for the equivalent SAG-based circuit, so that HPGR must offer sufficient operating cost benefits to offset the additional capital costs over an acceptable pay-back period. It is usually necessary to undertake comprehensive project-specific trade-off studies to quantify this effect.This paper describes the processes involved in the execution of a typical SAG-HPGR trade-off study, from the preliminary assessment of ore characteristics and project criteria, through testwork, circuit modelling, equipment selection and cost estimates, to a project-economics comparative assessment of the options. The trade-off study determines both the technical feasibility of the respective technologies and their commercial viability in the given project setting.The paper concludes with a cautionary note to the effect that, while HPGR has many potential benefits, it is not a panacea, and that, for some ore types and project conditions, the more established conventional technologies are often more appropriate."

Jan 1, 2010

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Herbert H. Einstein

The innate variability of natural materials and processes causes uncertainty in the models representing the natural phenomena and uncertainty in estimating the parameters that are used in these models. Reliability analyses, in contrast to the traditional factor of safety approach, are well suited to a rational incorporation of uncertainty in design and exploration decisions. Probabilistic kinetic and kinematic analyses were developed and combined to form reliability analysis methods. With one method the reliability, i.e.) the probability of failure, of an individual 2-plane wedge in a slope can be determined. The other method is aimed at slopes with a single slope parallel set of joints. In each case two approaches were developed, an encompassing one relying on computer codes and a simplified or summary approach relying on charts or pocket calculator computation. A major contribution of these approaches is the treatment of joint persistance. Instead of having to assume a certain persistence, it is now possible to use exploration data on joint geometry and to include the persistence effect rigorously.

Jan 1, 1979

By Robinson KJ

Education in Australia now has to respond to a very wide political and policy agenda. The political emphasis is upon increasing participation and retention rates with a view to greater graduation rates in `high-tech' disciplines. There is an implied linkage between `education' and `economic well-being'. Our argument is that equalitarianism in education tends towards mediocrity. In this context many Geoscience educators view the future with pessimism. The argument is that science has been `sold short' and needs revitalising. We contend that Geoscience coursework should be a feature of both secondary and tertiary education in Australia. To this end we propose six policy initiatives to increase the content of Geoscience in education programmes.

Jan 1, 1989

The re-use of waste water from coal preparation plant tailings is always desirable, but is generally problematic in terms of solid-liquid separation. Dewatering and disposal of coal slurry at a high percentage of moisture poses a major technological and environmental challenge to mining and mineral processing industries world-wide. Characterization and flocculation of these coal tailings reveals that the separation of fine coal tailings depends on factors such as size distribution, slurry viscosity, zeta potential, pulp density, circuit design, plant operating parameters, and the behaviour of solid particles in an aqueous medium. The present study was carried out on -600 mm coal tailings collected from a coking coal preparation plant of Jharia Coalfield, India, using anionic flocculent. Characterization studies revealed that the zeta potential was highest (-44 mV) at a pH of 9.0, the size range of the particles was 1.1?700 m, and the average ash content was 62.57%. Flocculation studies were performed at different solid concentrations, pH values, and polymer dosages. The results indicated an efficient settling rate of 178.15 mm/min at 8% solid (w/w) at a flocculent dosage of 32.50 g/t solid. The turbidity of the clear liquid obtained was 7.42 NTU.

Jan 1, 2014

THE following really forms the second part of, or a sequel to, a paper, " Ventilating Metalliferous Mines: a Method of Attack," read before the Broken Hill Branch of the Australasian Institute of Mining and Metallurgy in May, 1920. In that paper the writer advocated a consideration of the question of ventilation in metal mines from a different aspect to that 'which had hitherto prevailed locally. Various factors regarded as having an important bearing on the subject were set forth, together with the results of observations made during ventilation tests carried out at the mining department of the Zinc Corporation.During the subsequent discussion the question was raised of the possibility of any practical application of the method of attack described, and also whether the theoretical considerations mentioned were likely to be of any real utility to the mining engineer engaged in ventilation work in a metalliferous mine.

Jan 1, 1923

By R. Mohan Srivastava

"The goal of estimation is considered in the light of decision analysis. A simple example reveals the essential elements of decision-making in the face of uncertainty. A second example shows that these elements are also key features of many mining decisions. These two examples cause us to revive an old probabilistic notion that the goal of estimation should be to quantify what is unknown. The conditional probability distribution provides the complete statement of one's uncertainty. Once the conditional probability distribution has been established, one should retain as an estimate the value which minimizes some objective loss function. A third example shows how the ""best"" estimate depends on the chosen loss function. Current practice is almost exclusively based on the least squares method, which assumes a loss function which penalizes underestimation and overestimation equally. This is unfortunate not only because symmetry is an unrealistic assumption but also because mining offers a rare opportunity to state the loss function directly in terms of profitability. Both the theoretical framework and the practical tools exist to allow us to reconsider the conventional notion of the ""best"" estimate. IntroductionThis paper looks at estimation in the mining industry from the point-of-view of decision analysis. Virtually all decisions depend on estimates since few of the important parameters are ever known exactly. In this paper we will be referring mainly to the estimation of ore grades, though the approach discussed here is generally applicable to any decision in which relevant information is uncertain.In the first section we look at a very simple example of decision-making in the face of uncertainty. We will then tum to a mining example and see that the essential features of the simple example still pertain. From these two examples it will be clear that the decision analysis approach rests on two key concepts: the conditional probability distribution and the loss function. A third example demonstrates how different loss functions produce different ""best"" estimates from the same conditional probability distribution. In the final sections we willexamine the current practice of estimation in the mining industry. Though the tools for estimating the conditional probability distribution already exist, a change in the way we think about ""best"" estimates is needed. Very little attention is presently paid to the loss function even though it is readily available in many mining applications."

Jan 1, 1987

By Russel Delmar

Construction of Ontario Power Generation?s 12.8-m diameter, 10.4-km long water diversion tunnel in Niagara Falls, Ontario, is underway. The tunnel is being excavated by means of a 14.44-m diameter open gripper Tunnel Boring Machine. The tunnel lining is constructed as a two-pass system with the initial lining consisting of rock bolts, mesh, steel channels or ribs, and shotcrete, and the final lining consisting of pre-stressed cast-in-place concrete with a waterproof membrane. This paper describes salient design and construction aspects as follows: ? Regional and Site Geology ? Tunnel Layout and Design ? TBM Tunnelling and Cast-in-place Concrete Lining Construction

Jan 1, 2008

By S. M. Spottiswoode

The aim of the hybrid location method is to improve seismic event locations by reducing the effects of errors in the wave velocity of ray paths between each event and each recording site. We report on further enhancements made to the hybrid location algorithm, which is based on the double-difference method developed by Spottiswoode and Milev1and Waldhauser and Ellsworth2. The term ?double-difference? refers to the residuals between the observed and theoretical travel-time differences and are obtained using either picked arrival times or various measures of time differences obtained from waveform pairs. These residuals are minimized for pairs of earthquakes at each station while linking together all observed event-station pairs. An important enhancement is that the double-difference term uses the median arrival time residuals to reduce the effect of outliers on the system of equations. In addition, the hybrid locations are further constrained by considering events of known locations, in this case along lines of development blasts. We relocated some 20 000 previously located seismic events in the Driefontein 5E area; 5 800 of these events were considered to have been development blasts and we constrained their locations to lie on the straight lines joining about 2 150 survey pegs from the mine?s database. Relocated events were shown to distribute more closely around advancing faces than had been the case before relocation. Wave velocities from the development blasts show evidence of anisotropy.

Jan 1, 2005

By Michele Ashby

The mining industry is facing new risks from peak commodities, the energy and economic crisis and stock market pressures. The Green Mining Industry Initiative is a risk management strategy for the future of the mining industry. Defining the Risks The bad news is peak commodities, energy and economic crisis and stock markets collapsing are the issues that are already hitting everyone?s bottom line and draining the treasuries of every mining company around the world. Higher energy costs are affecting the bottom line more than ever before, which is creating more risk for companies. Mining companies have major land positions around the world and they have major energy needs. Uncontrollable increases in energy costs, increased regulations for diesel fuel emissions and energy intermittencies are costing mining companies more time, money, and man-power, which are cutting into profits and hitting the balance sheet. The good news is, there are practical energy solutions which are off the grid, tried and true methods which can be implemented in a cost-effective manner and will increase profitability and save shareholder values as well as energy security for these companies and their projects. To date, most of the mining resource industry has not yet considered or used other forms of power like clean, sustainable, or alternative energy for their own energy needs. The reasons have primarily been pushback from the mining industry due to beliefs of older technologies in alternative energy, a lack of understanding of the cost advantages long term, and perceptions of environmental relativity.

Jan 1, 2008

By Bruce Geller

Attending the Prospectors and Developers Association of Canada (PDAC) meeting and exhibit has become an annual tradition for many in the mining industry. Similar to last year’s synopsis, this report is an overview of the 2003 conference from the eyes of a consulting mineralogist. It is supplemented by conversations with other participants. And it examines the conference handouts. Certain segments of the mining industry have seen improvement throughout the year in terms of metal prices, stronger demand and renewed interest by the investment community. Other segments continue their decline due to depressed commodity prices, higher oil prices, a continued weakness in the global economy and war uncertainties. SARS was known to the world, but it was not a Toronto epidemic during PDAC. In short, this year’s PDAC was permeated by an air of anxiety about the Middle East.

Jan 1, 2003

By S Hapugoda, J R. Manuel, M J. Peterson

Microindentation testing using the square–pyramid–shaped Vickers indenter is a well-established technique to determine the microhardness of minerals and materials. However there is a paucity of published microhardness data from Fe ore samples. It is acknowledged that an iron ore’s particle mineralogy and texture is critical to its processing properties, and it is therefore considered that the microhardness of different mineralogical/textural types may also relate to these properties. Mineral microhardness potentially provides inputs to the modelling of breakage characteristics during comminution, as well as the relationship between mineral chemistry and microhardness, and mineral microporosity and microhardness. Microhardness can be determined as single crystal microhardness, for more coarsely microcrystalline samples, or as ‘aggregate microhardness’ for cryptocrystalline or finely microcrystalline samples.Variations in the texture and mineral chemistry of common Fe ore minerals (eg martite and microplaty hematite, ochreous and vitreous goethite etc) are well established and this study provides microhardness data on different textural forms of Fe (oxyhydr)oxides from a variety of different Fe ore deposits. The data indicated that in general, the mineral grain size, microporosity and texture were the main influences on Fe (oxyhydr)oxide microhardness. There were no apparent systematic variations between microhardness and minor element mineral chemistry, with the possible exception of Al content in goethite (for goethites with Al content >0.5 wt per cent), and for goethite total element contents >90 wt per cent (determined by electron probe microanalysis, EPMA). Higher Al concentrations and lower total element concentrations in goethite EPMA analyses correlated with lower goethite microhardness. Microporosity and grain size were more important than texture to hematite microhardness. Different textural forms of dense hematite (eg martite, recrystallised interlocking hematite and specular hematite) with similar grain size exhibited comparable microhardness. Microhardness values for hematite and hydrohematite with little or no evident microporosity were also similar, whereas more porous forms of martite, microplaty hematite or hydrohematite exhibited lower microhardness.CITATION:Peterson, M J, Manuel, J R and Hapugoda, S, 2017. Microhardness testing of hematite-goethite Fe ores – implications for their textural characterisation and geometallurgy, in Proceedings Iron Ore 2017, pp 319–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Budiselic C, Hefter G

The uptake of gold by activated carbon from acid chloride solutions involves the reduction of gold(IIl) to metallic gold. Deposition occurs only on the surface of the carbon at localized active sites at first, and subsequently at less active areas. The rate of uptake depends on the surface area of activated carbon, which confirms results from a recently published study (de Siegel and Soto, 1984). Increased rates of uptake were observed at higher temperatures and lower chloride concentrations due to the decreased stability of AuCI4-, the major gold(IIl) species present. Recoveries of gold approached 100 per cent for a contact time of 60 minutes at 20°C in a well stirred solution initially 5 ppm in gold(III) and containing 0.5 per cent w/v coconut-shell carbon. The presence of 0.25 Mnitric acid or 100 ppm iron(IIl) had no detectable effect on either rate or efficiency of gold uptake.

Jan 1, 1985

By Frank P. Frandina, Michael J. Loehr, Paul E. Gabryszak

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. In the Preliminary Engineering stage, 30 existing tunnels were assessed and 28 were found to need clearance improvements to allow the use of double stack trains. Alternative tunnel enlargement methods were developed to achieve the desired clearance improvements, while maintaining structural integrity and minimizing disruption to train traffic. This paper summarizes the geometric and condition investigations of the existing tunnels, as well as describes the preferred methodologies to achieve the desired clearance. The clearance improvements will be implemented beginning in the summer of 2007.

Jan 1, 2007

Norton Co., a manufacturer of abrasive products and diamond drilling and coring bits for oil and gas exploration, is building a $19.1 million addition, scheduled for completion in late 1980, to the Huntsville, AL. The plant makes alumina-zirconia abrasive grains used in grinding wheels and coated abrasives. ALUMINUM Martin Marietta Aluminum Inc. announced plans to expand production capacity of its 112,000-ton-per-year primary aluminum smelter at Goldendale, WA to 177,000 tons per year. The $125 million expansion was scheduled to come onstream in 1981. The Aluminum Company of America announced plans to restart a fourth potline during October at its 185,000-ton-per-year Point Comfort, TX primary aluminum smelter.

Jan 1, 1979

By Lottrey A. L, Sowerby B. D, Cutmore N. G

On-line monitoring of low rank coal quality during input to a process has the potential to provide benefits through: ò anticipation of coal quality variations prior to utilisation; ò provision of a tool to help determine the influence of coal quality on process behaviour, and ò provide a direct measure of coal quality for pricing. Moisture and ash are the two most significant coal quality parameters for combustion. They determine the energy content which can be derived from the coal and the problems arising from the presence of ash in the process (eg ash fouling, corrosion, erosion, particulate emissions and ash disposal). Extensive pilot-scale testing and full-scale experience has shown that specific coal/ash constituents (eg Na2O/ash ratio, acid-soluble aluminium, silica, sulphur contents, etc) are also important for the behaviour of Latrobe Valley brown coal during combustion, ash formation, deposition and removal of ash in precipitators and furnace ash hoppers. This paper discusses the range of on-line analysis techniques which have been investigated and their application to low rank coal analysis. Preliminary results from a joint SECV/CSIRO project which aims to develop two separate advanced instrument systems are also presented. These systems are based on: ò microwave attenuation and phase shift - for direct determination of moisture content; and ò inelastic neutron scattering - to provide total hydrogen, carbon, chlorine and ash contents, with potential for calculation of moisture content, specific energy, sodium content and Na20/ash ratio using correlations.

Jan 1, 1992

Jan 1, 1994