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By Madgwick J. C

Bacterial leaching of museum grade chalcopyrite and chalcopyrite concentrates at low sorptive relative humidities (55-91 per cent rH) was demonstrated. Optimum release rates were 13 and 27 mg/gram/100 days copper (Cu++) at 91 per cent and 80 per cent rH and 12 and 33 mg/gram/100 days iron (Fe++) at 80 per cent and 73 per cent rH for concentrate and "pure" chalcopyrite respectively. The optimum copper release rates occurred between 73 per cent - 86 per cent rH and 30-40 mM acid concentrations. Bacterial copper leaching rates were some twenty times slower for emersed copper concentrates, at low relative humidity, compared with submerged cultures. Bacterial copper solubilization was almost quantitatively inhibited above 150 mM acid levels (< pHO.8).

Jan 1, 1984

The world is getting flatter through internet, mobile phone technology, relatively low cost travel, massive outsourcing of manufacturing to China and the transfer of company backroom operations to India. In the iron and steel industry, however, things will remain relatively the same with slow gradual improvements in technology; only the geographic location of plants may change over time. Or will it? The blast furnace smelting process has remained largely unchanged since 1828 when James Neilson came up with the idea of preheated air being delivered to the tuyeres. Likewise, oxygen steelmaking that takes molten iron from such blast furnaces has remained conceptually unchanged since Sir Henry Bessemer invented an air-based system in 1856. These two processes are the core of integrated steel mills that we know today. Typically such mills consist of coke ovens, sinter plant, blast furnace, oxygen steelmaking, continuous caster, rolling mills and metal coating lines. In the intervening 150 years the only real disruptive technology to the integrated steel mill has been the minimill. Based on the use of the electric arc furnace (EAF), in conjunction with a continuous caster and rolling mill, the term minimill is used because steel products are produced at down to one-tenth the scale required for economic operation of an integrated mill, with the EAF producing molten steel using largely scrap steel as its feed, as against transforming coal to coke (coke ovens), iron ore, coke and limestone into molten iron (blast furnace) and molten iron to steel (oxygen steelmaking). There are, however, a number of technologies in development that may cause a paradigm shift in the way steel products are produced and perhaps push the evolution of the minimill as a disruptive technology. Two examples are direct iron smelting, where iron is produced in a matter of seconds by injection of ironmaking feed materials into a molten bath, and thin strip casting, where molten steel is cast into 2 mm strip or less, in similar time. Both have Australian connections. A leading iron smelting technology is the HIsmelt« process, which has its first commercial application at Kwinana, Western Australia, where a joint venture of international parties, consisting of Rio Tinto and the Nucor, Mitsubishi and Shougang corporations, are in the stage of ramping up commercial production. The leading strip casting technology is the Castrip« process that arose from development work done by then BHP Steel, with IHI of Japan, at Port Kembla, New South Wales in the 1990s. Nucor followed this work up, building the first commercial plant for the technology at its Crawfordsville site in Indiana in 2001 and has recently announced an intention to build a second plant in the USA. While both technologies are only into the early stages of commercialisation they are likely to change the face of iron and steelmaking as we know it over the next 20 years. This paper elaborates on the technology of the two processes, why they could change the face of the iron and steel industry forever, what might drive the rapid change and what the changes may look like.

Jan 1, 2006

By H G. Poulos

Prediction of ground deformation caused by soft ground tunnelling is an important problem facing design engineers. The ground deformations are caused by the closure of the gap formed around the tunnel due to the tunnelling procedure and soil intrusion via the tunnel face into the tunnel. There are three different approaches that are commonly used in practice to estimate the ground deformations due to tunnelling, namely, empirical methods, analytical methods and finite element methods. One of the important issues of tunnelling in urban areas is the assessment of the likely impact on adjacent pile foundations of ground movements arising from tunnel construction. The main objectives of this paper are two-fold: first, to assess the available methods to estimate the tunnelling-induced ground deformations, and second, to examine the effect of such ground deformations on adjacent piles. Analytical solutions to predict the tunnelling-induced ground deformation developed by the authors are used in this study. These estimated ground deformations are imposed on the pile in simplified boundary element analyses to compute pile responses. The influence of various factors such as tunnel geometry, ground loss ratio, pile diameter and ratio of pile length to tunnel depth are examined in this study.

Jan 1, 1999

By Daoust G, Dubois JF

The optimal sequence of decisions on rates of production and cutoff grades is obtained by a dynamic programming model. The main parameters are : 1. the size of the deposit, average grades and grade distributions, 2. the operating costs of mining and concentration, 3. the investments in mine and mill, 4. the smelter charge, 5. the price(s) of the metal, 6. the recovery and the grade of the concentrate, 7. the rate of interest, 8. the taxation formulae, 9. the upper limit to rate and the rate interval and 10. the upper and lower limits to cutoff and the cutoff interval. An amount of ore can be mined at various rates while applying various cutoff grades. It is assumed that a decision to mine at a certain rate during a period conducts to a certain state regardless of the cutoff grade. This assumption which is valid for several

Jan 1, 1977

The Kyaukpahto gold deposit is located at latitude 23¦ 47Æ 55" N and longitude 95¦ 56Æ 35" E in the Kawlin-Wuntho district, Sagaing Division, Myanmar. Gold mineralisation is hosted in sandstone of the Male Formation (Eocene) and occurs as stockworks and disseminations. The high-grade gold mineralisation is locally concentrated in a breccia zone. The gold deposit is closely associated with a NNE-SSW trending fracture system that forms tensional open fractures. These tensional zones are thought to be directly related to the Sagiang transfer fault system that experienced several hundred kilometres of northward dextral movement during the post-Upper Miocene. Major sulfide minerals are pyrite and arsenopyrite with minor galena, chalcopyrite and sphalerite. Gold mineralisation is associated with intense silicification, sericitisation and argillic alteration. Primary Type I fluid inclusions in the quartz from the mineralised zone are 5 to 15 ¦m across and yield homogenisation temperatures of 239¦ - 310¦C and salinities of 1.2 - 10.9 wt per cent NaCl equivalent. Laser Raman spectroscopic analysis indicates the presence of CO2 and CH4 in Type II fluid inclusions. Sulfur isotope analysis of disseminated pyrite in the ore zone by the laser ablation method indicates d34S values from -5.48ë to +5.53ë. The geology, alteration, ore mineralogy, fluid inclusion microthermometry and sulfur isotope data of the Kyaukpahto deposit are consistent with an epithermal ore deposit model for the deposit. However, the presence of CO2-liquid bearing fluids and the detectable CH4 in the gaseous phase of the fluid inclusions conflict with a typical epithermal origin for the Kyaukpahto deposit. The host siltstone and mudstone sequence, trace element geochemistry, and the disseminated nature of sulfide and gold mineralisation are also common characteristics of a sedimentary rock-hosted gold deposit, and these features may indicate a Carlin-like affinity. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By M H. Mian

Much has been published on resuspension of sediments in lakes and estuaries. In general, resuspension has implications on transport and release of contaminants from the sediments. It has been shown that wind-induced waves contribute to erosion of sediments, which are then distributed to various sections of the water body by currents. Empirical equations formulated on the basis of cohesionless sediment behaviour have been applied to the design of a few tailings ponds in different parts of the world, especially in the selection of the necessary depth of water to minimise negative environmental impacts. The paper highlights the shortcomings inherent in these equations using field-measured data from a tailings site in Canada. Laboratory measured tailings properties are used to identify critical shear stresses required to initiate tailings erosion. The influence of cohesion on resuspension of fine-textured tailings is discussed.

Jan 1, 2003

By Netchaef P

A rationale is presented for the use of vegetation on mine dumps to minimise runoff and infiltration which become vehicles for potential pollution. The unique topography of mine dumps promotes high atmospheric advection which leads to extraordinary energy levels for evaporation discharge - the driving force of vegetation "pumps". This effectiveness is mainly a function of how well the vegetation will grow on a given site. Recent advances in technology allow water discharge by vegetation to be measured semi-automatically, accurately and cost effectively. As a result the basis now exists for a thorough evaluation of the optimum mine dump vegetation cover. This paper presents the current status of dump rehabilitation as seen by the mining industry. The significant prospects for use of vegetation to minimise mine water related problems with subsequent savings in capital and operational cost are also outlined. However, to examine the crucial questions of optimum hydrological ability, suitability and cost effectiveness of various types of dump vegetation a proposition is made to interested parties in the mining industry: The CSIRO needs potential study sites to evaluate the hydrological ability of vegetation under mine dump conditions.

Jan 1, 1988

By T Perera, B Fan, S Thang, T Hsia

Minerals are valuable resources and critical elements for a broad range of biological and technological applications, including technological developments to improve energy efficiency and the global movement to promote a low-carbon economy. However, in order to extract these critical metals, large amounts of waste and toxic chemicals are generated, as well as the use of high energy and large amounts of water consumption. Froth flotation is one of the most commonly used processes to separate and collect high-value minerals, but it still has some limitations, including low flotation efficiency performances using existing collectors and other reagents. Therefore, there is an urgent need to design and develop new metal-specific collectors to more efficiently separate and recover valuable minerals and to allow bulk water recovery from flocculated tailings. In this research, we propose to use our newly designed and synthesised novel collectors derived from a type of vitamin E (α-tocopherol), a relatively inexpensive and non-toxic natural molecule. As a potential collector-building block, α-tocopherol has a long hydrophobic carbon chain that facilitates the attachment to air bubbles during the froth flotation process. In addition, the phenol group of this molecule can be easily modified to incorporate various functional groups for targeting different types of minerals. Furthermore, α-tocopherol can be converted into a monomer for polymerisation by the reversible addition-fragmentation chain-transfer (RAFT) process, which can provide us with polymer based-collectors with high precision control of molecular weight and architecture. So far, small-scale qualitative experiments on α-tocopherol-based collectors have been performed with good results, which indicates the feasibility of these compounds as novel collectors for improved froth flotation processes.

Aug 24, 2022

By P Elliott, D Pershke

In a minerals processing context, sustainability is about using natural resources more efficiently to achieve maximum economic benefits with minimal environmental impacts. It embodies five overarching themes, which the paper will illustrate with practical examples from Australian minerals processing plants. These are:resource utilisation and materials efficiency,process waste reduction and enhancement of co-product values,reduction of water use and impacts,reduction of energy requirements and greenhouse gas emissions, andenhanced control of minor elements and toxic materials. Sustainability could be embedded profitably in minerals plant design in three dimensions: 1.technology,2.design, and3.operations. This presentation discusses a set of principles that could be applied to minerals processing technologies and provides an outline of sustainability assessment and opportunities evaluation tools. The application of the tools is illustrated through a case study by analysing a suite of nickel processing technology routes. The analysis reveals that current generation of nickel processing technologies do possess real potential to emerge as sustainability champions in integrated processing of nickel ores and concentrates, if they are designed, engineered, and operated for sustainability and adapted effectively to site specific constraints and opportunities. The paper will address data gaps and uncertainties regarding the impact of scaling up of pilot-plant performance, and provides strategies to overcome them.

Jan 1, 2006

By J R BISHOP

Geophysical techniques are being increasingly used down exploration drill holes as deeper and more elusive targets are sought. This paper lists the various methods available and discusses the applications using a number of examples.

Jan 1, 1992

By Lloyd F, Arnold D. A, Hagan T. O

This paper investigates the problems that are encountered in mining at extreme depths. It looks into the rock mechanic aspects, especially the high stress levels that will occur, and the hazard of rockbursts. Furthermore, environmental problems are discussed, with refrigeration and reduction of neat loads being major methods of maintaining ,sorkable conditions. The paper concludes that it will be of tmost importance to have a planning team of Tne highest quality to ensure that conditions are maintained so that work can be carried out safely and under reasonable conditions.

Jan 1, 1986

In 1955 the annual production of steel at Australian Iron and Steel Pty. Ltd., Port Kembla was 1.2 million tonne and over the following two decades this had progressively increased to the present capacity of 5.4 million tonne per annum. This increase in productivity has also been accompanied by important developments in steelmaking technology and these are explained in the chronological order in which they have taken place. Reference is made to the use of oxygen in open hearth furnaces, the B.O.S. process, the Argon-Oxygen decarburisation process for stainless steel, vacuum degassing and continuous casting. When the vacuum degassing and continuous casting units are commissioned, the Port Kembla Works will have achieved a standard of steelmaking technology equal to any in the world.

Jan 1, 1976

By H E. S Moorcroft, D Scott

The increasing mining depths of South African gold mine deposits are resulting in ever-increasing heat loads associated with depth and the geothermal gradient. Together with changes in the mining horizons brought about by the depletion of older, shallower, high-grade reserves, this leads to the need for the continuous review and redesign of cooling requirements. Traditionally, cooling requirements were met by using a combination of cooling strategies, including bulk air cooling on surface and underground. If this proved to be insufficient, chilled service water and secondary remote air-cooling systems were introduced. This paper reviews these practices in order to provide a cost-effective means of catering for the introduction of hydropower at the Gold Fields Ltd South African operations. Some of the equipment that has been developed to meet the requirements of both hydropower and refrigeration includes hydropower fans, cooling coils and in-stope venturis. These are individually described and discussed, together with their roles within the greater strategy. The planned change in the cooling strategy and the employment of these technologies have effectively doubled the cooling available, from 10 MW to more than 20 MW, extracted from the hydropower water used to drive the mining equipment. In conclusion, the cooling strategy described allows a total heat load of approximately 52 MW to be successfully ventilated and cooled through the use of combined surface and underground refrigeration installations, and through the use of hydropower-chilled water.

Jan 1, 2005

It is no longer adequate when starting a new mine to simply select the best equipment. Today's competitive international commodity markets demand superior efficiency which requires systematic involvement of people in continual improvement of production and commercial processes. True Total Quality of Management (True TQM) principles provide an operating philosophy for maximising productivity and minimising unit costs of output. The presentation will show the practical and successful use of these principles. This paper will introduce the case study and provide background material on True TQM.

Jan 1, 1995

By S Hapugoda, M Peterson, A Haileslassie, A Poliakov, E Donskoi, L Lu

Most metallic iron in the world is produced in blast furnaces from different feed stocks – sinter, lump ore and pellets. Sinter is the main iron-containing feed to the blast furnace and can constitute up to 70–85 per cent of the total ferrous burden. As sinter quality is a key element for stable blast furnace operation, the textural, chemical and physical characteristics of the sinter are very important. Two major factors that affect sinter strength are mineralogy and porosity. This study utilised optical image analysis (OIA) to characterise sinter mineralogy, and the results were compared to those obtained by manual point counting under the optical microscope.Two major mineral characteristics of iron ore sinter are the presence of primary (unreacted) and secondary (derived from melt) hematite. Standard OIA, which is based on RGB thresholding, is not able to distinguish them as they have the same reflectivity; however, primary and secondary hematite in iron ore sinter have a different morphology. The CSIRO-developed OIA software Mineral4/Recognition4 has a unique feature to identify various textures/morphologies of the same mineral. Together with other capabilities of the Mineral4/Recognition4 software, this feature was used to identify different types of hematite and silico-ferrite of calcium and aluminium and other common sinter phases, such as magnetite, larnite, glass and remnant aluminosilicates.A visual comparison of the sinter mineralogy present in optical photomicrographs and that present in the mineral maps created automatically by the Mineral4 module of the CSIRO software confirmed the accuracy of the automated mineral identification.CITATION:Donskoi, E, Hapugoda, S, Lu, L, Poliakov, A, Peterson, M and Haileslassie, A, 2015. Advances in optical image analysis of iron ore sinter, in Proceedings Iron Ore 2015, pp 543–548 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By I Auranen, J Raatikainen

IMA Engineering (IMA) and Mine On-Line Service (MOLS) companies have used on-line sensors for analysing ore and waste rock in mining for more than 25 years. Today IMA on-line sensors are used in various stages of the mining process including on-line analysis of drill cores, drill chips, ore and waste in loader bucket, ROM ore analysis on belt conveyor belt and in bulk ore sorting and in slurry analysis in concentrators. During years of extensive field experience and testing we have found that the waste rock dilution and ore losses create much larger economic and environmental losses than has been previously recognized. According to our studies the main reason is limited number of analysis already in exploration when drill cores or drill cuttings are used in block modelling. The same happens in production because too few and biased samples from benches are used to estimate the ore grade. Much more than today estimated amount of waste enters the mill and considerable volumes of ore losses happen at the same time. The ore grade on the benches and in muck piles is averaged and “homogenized” with averaged and biased samples. These are the main root causes of waste rock dilution and ore losses. Sensor based preconcentration can be the remedy to waste rock dilution and ore losses. This presentation will show examples of the use of on-line sensors in preconcentration when analysing ore and waste rock in drill cores, drill cuttings, on conveyor belt and in bulk ore sorting. Waste rock removal in preconcentration has direct effect on energy consumption in crushing and grinding and chemicals in concentrator. In concentrator waste is separated and goes to tailings pond, however, preconcentration directly reduces the volume of the tailings. In our presentation we will cover cases in base metals and in gold mines.

Nov 10, 2020

By Lawrence PR, Hoffman W

The dissolution of gold from various ore-bodies is discussed in terms of extraction rates and reagent consumptions during leaching. Gold dissolves slowly in cyanide but reagent consumptions are usually satisfactory. In almost all cases where excessive cyanide consumptions occur, similar high consumptions result with other lixiviants. Recovery of gold from cyanide solution is well established and comparatively simple technology.Gold dissolution in thiourea is faster than cyanide but significant consumptions of thiourea, due to both adsorption and oxidation, occur. Gold recovery from thiourea solutions is likely to be more difficult than from cyanide.Chlorination of gold is very fast in acidic conditions but excessive consumption of chlorine occurs for ores containing greater than 0.5% S. Reprecipitation of gold and handling of acidic chlorine solutions are both significant problems. The mechanism of gold reduction onto activated carbon creates difficulties in the carbon in pulp process for recovery of gold but means a simplification in the production of bullion from loaded carbon.

Jan 1, 1984

By S Prakash, M Danish, D Kumar

The green energy transition is speculated to cause an increase in the demand for raw materials while recycling rates are improving; discoveries are required to maintain supply. Geological remote sensing offers a cost-effective way of exploring mineral resources. While satellite and airborne imaging are routinely used for exploration targeting, a gap remains at the outcrop scale. Hyperspectral imaging (HSI) is advantageous for large-scale regional mapping, typically performed from satellite or airborne platforms. Accurately mapping geological lithologies remains challenging in inaccessible areas, such as rough terrain or mine sites. Proximal sensing techniques can boost geological activities’ reliability, safety, and efficiency in exploration or during mining activities. It also generates objective, reproducible results and valuable raw data that can be archived, further processed, and re-interpreted. Ground-based hyperspectral imaging of outcrops has steadily increased during the last decade due to sensor development and better processing routines. There is often a big technology gap related to mineral mapping, integration of images and spectra (reduction in manual identification of minerals and types) and hyperspectral data visualisation through remote sensing. TEXMiN Foundation, in collaboration with its industry partner Dassault Systemes Foundation, carried out the project, ‘Developing Hyperspectral Image Processing and Analysis, build a rich library of Hyperspectral images of a vast range of minerals from India which will help in increasing prediction accuracy of mineral deposit for mining exploration’.

Sep 1, 2024

By I Doye

Acid mine drainage is a serious environmental problem caused by the oxidation of sulfide minerals responsible for highly acidic, sulfate and metals-rich drainage. Several methods of mine waste management have been developed that reduce liabilities on environment. Layered co-mingling of waste rock with compacted tailings, covers with capillary barriers effect, and co-disposal of waste rock and tailings are these new methods which are used to reduce the formation of acid mine drainage. These methods shield waste rock dumps from oxygen. These techniques could prevent oxidation reaction. In this study, alkaline industrial wastes are used with acid generating tailings to inhibit acid mine drainage. The alkaline wastes selected are cement kiln dust (CKD) and red mud bauxite (RMB). These alkaline materials are used to keep neutral conditions in the fine material layer and to inhibit the metabolic activity of Thiobacillus ferroxidans which catalyses the oxidation of sulfide minerals. A series of timed static leaching tests were performed by reacting samples of mine tailings with two, five and ten per cent alkaline material in order to characterise geochemical balance between liquid and solid phases. Column tests have been set up with oxidised tailings, waste rock, CKD, and RMB. Column tests have been carried out to simulate layered co-mingling, covers, liners, and co-disposal of waste rock and tailings. Column leach tests were conducted in order to investigate the long-term neutralisation potential of alkaline materials and the drainage water quality. Bacteria counting were performed on each sample after testing. The results obtained show that the addition of alkaline materials permit the retention of near neutral conditions in the fine material layer, thus increasing water quality and preventing bacteria development. In fact, the pH results show that the use of five per cent, ten per cent CKD or ten per cent of a mixture of CKD and RMB permit the retention of neutral pH conditions in the reactive layer. At these percent rates, the concentrations of Al, Fe, Cu, Zn, and SO4 in solution are significantly reduced compared to those obtained with the tailings only. In presence of waste rock, the relative position of the fine material layer is important. When the fine material layer overlaying reactive waste rock is composted of reactive tailings with ten per cent CKD and ten per cent (CKD:RMB), a delay was observed before achievement of near neutral pH. The neutral pH conditions remain stable over time. The mixture of CKD and RMB provides a better short-term neutralisation than the use of CKD alone. The use of alkaline materials is beneficial in order to reduce the concentrations of Fe and other metals such as Cu and Zn as well as the number of viable bacteria. The use of ten per cent RMB alone does not involve the neutralisation of reactive tailings. In the cases where the fine-grained layer are below or mixed with the waste rocks, the near neutral pH values are directly reached with ten per cent CKD. However, the pH values decrease rapidly and the number of viable bacteria increases.

Jan 1, 2003

By K Baskaran, T McKenzie

Sustainability is becoming increasingly important in the mining and mineral processing industries and must incorporate the associated waste products. Acid mine drainage (AMD) is one such by-product and is one of the most serious environmental problems facing the minerals industry today. The oxidation of sulphidic mine wastes often continues for a substantial period of time after mine closure, resulting in difficult and costly remediation and rehabilitation works. Mining companies are often reluctant to spend increasing amounts of money on waste treatment when the mine life is limited or even finished. Hence a simple, low maintenance and low-cost method of treating AMD is required. Whilst this paper does not address the issue of AMD, it does propose methods for removal of individual species from AMD with potential benefits, including raising AMD pH. A novel concept of using biosolids as a biological adsorbent, or æbiosorbentÆ, of metals from AMD is being investigated at a laboratory/pilot scale level. Biosolids are a by-product resulting from the biological treatment of wastewater, and have been previously shown to adsorb metals from aqueous solutions. This could lead to an environmentally sustainable or ægreenÆ method for treating both AMD discharges and disposing/reusing the biosolids. The result of a laboratory-scale study of the biosorption of Zn(II) is presented in this paper. Physical parameters including reaction kinetics, mixing speed and solution pH were investigated. Solution pH also rose an average of 2 pH units over the 24 hour equilibrium time û a valuable side effect when treating acid mine drainage. The outcome of the study highlights the usefulness of biosolids as a biosorbent for the removal/recovery of metal ions from acid mine drainage. A simple, low-cost treatment technology requiring low maintenance would be beneficial to the mining industry to address some issues relating to AMD and would help integrate environmental and economic considerations into sustainable environmental management.

Jan 1, 2002