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By W J. Bruckard, M J. Vaisey

Ashton Mining Ltd (Ashton) and Lynas Corporation Ltd (Lynas) have established a joint venture partnership to develop and process rare earth oxides (REOÆs) from the Mt Weld deposit in Western Australia. The deposit is located in a deeply weathered volcanic carbonatite structure that contains approximately two million tonnes of rare earth oxides at an average grade of 20 per cent REO. As part of the 1999/2000 feasibility study currently being undertaken by Ashton and Lynas, an extensive laboratory beneficiation test program was undertaken by CSIRO Minerals on diamond drill core samples from the Mt Weld orebody. The aim was to develop a flowsheet, based primarily on flotation that could be confirmed at pilot plant scale. The target concentrate grade was 52 per cent REO with a REO recovery of at least 35 per cent. Two main ore types, nominated as CZ (limonitic siltstone) and LI (nodular limonitic ironstone) were identified for separate laboratory evaluation. The lower grade LI-type ore overlies the higher grade and more extensive CZ-type ore. The majority of the work was conducted on the CZ ore; only limited testing of the LI ore was undertaken. The latter contains a clay component that will present difficulties in processing due to its poor filtering and settling characteristics. Two processing options for treatment of CZ ore were presented for pilot plant consideration. One (Option 1) includes gravity concentration prior to flotation while the other (Option 2) includes finer grinding and four stages of open circuit cleaning. The benefits of each scheme are discussed in detail. Neither has been fully optimised and the definitive flowsheet is most likely to be a hybrid of the two schemes, incorporating the best features of each. Typical metallurgical results from each scheme were final concentrate grades of 49 per cent REO, 10-16 per cent Fe2O3 and 3.2-4.8 per cent CaO. REO recoveries were above 35 per cent in both cases. Features of the processes developed by CSIRO were the inclusion of a gravity concentration stage prior to flotation, a modified flotation reagent scheme, a change in the method of feed preparation, and incorporation of magnetic separation to upgrade final flotation concentrates. Metallurgical results obtained from flotation tests on LI ore were much poorer than those obtained for CZ ore. The best rougher/scavenger result, with the limited amount of testing so far completed, was an REO grade of 32 per cent with a recovery of 28 per cent. Further work is needed to develop a viable processing route for this ore type.

Jan 1, 2000

By Broome A

In a technologically oriented industry, it is important to understand and apply technology very consciously to create competitive advantage. Technology is not an activity which is simply restricted to CSIRO or the research and technology department. Technology improvement is a part of everyone's role. It is a way of life - the technology facet of continuous improvement. For this reason, The AusIMM has organised this Travelling Technology Forum - a series of presentations about automation in mining. To make the message more accessible, The AusIMM had originally planned to take the Forum to four regional mining centres: Mackay/Townsville, Singleton, Burnie and Kalgoorlie, but only one seminar was held, ie at Singleton in March 1997. Seminars at other locations were cancelled because of insufficient registrants. The presentation by Andrew Logan of BHP Cannington was not available for the Singleton forum. The aims of the forum were: ò to heighten awareness of the key technologies and their impact in the minerals industry in the medium term; ò to foster creative thinking; ò to encourage people to broaden their technical and commercial skills and develop individual networks and linkages based on an interest in these key technologies; ò to share information on the application of these technologies in the industry; ò to promote an enhanced appreciation of the need for an innovative culture; and ò to encourage staff to consider post graduate courses in technology management. The AusIMM wanted to not only raise awareness about `automation in mining' issues, but also to get technology in a more general sense back onto `centre stage'. The Forum was generously supported by CSIRO, Western Mining Corporation Ltd, BHP Coal Ltd, Aberfoyle Limited, Goldfields Ltd, Novacoal Australia Pty Ltd, Pasminco Ltd, and RGC Limited. The program was endorsed by the Centre for Mining Technology and Equipment (CMTE). Copies of the full papers are available from the authors, see `References'.

Jan 1, 1997

A method is presented for calculating the number of cycles of stress to failure of a drill rod from operating variables; a mathematical analysis by Cooper of the stresses present in drill steels is applied to the forged collar, i1i-in. hexagonal hollow drill steel in common use in Australia; and an estimation is made of the dry fatigue limits at various points along a drill rod.It is shown that these calculations predict failure at a 'point where failure rarely occurs, and do not predict that failure should occur where it does in practice. The reasons for this anomaly lie in the neglect of bending stresses in the stress calculations, and in failuredue to corrosion fatigue at a preferred section rather than to simpler fatigue under non-corrosive conditions.INTRODUCTIONIt has long been recognized that failure of metal sections by fatigue is influenced both by the number of cycles of stress imparted to the section (N) and by the magnitude of this cyclic stress (8). In this paper, both Nand Shave been calculated for rods which have failed in service, and whose operating history is known. While the calculation of the number of cycles to failure is·simple, the calculation of stress is more complex. The results of stress caIculations predict that failure should occur only hi short rods, and then preferentially at the tip end rather than the shank end.However, in actual fatigue failures of steel rock drill rods, approximately 75 per cent. of such failures are close to the shank end, and failures near the tip end are rare.The usual explanation given for this high incidence of shank-end failures is that at the point of failure there exists, in forged collar steels of the type common in Australia "hardness valley" or. "m'etallurgical notch". This narrow valley in hardness is a weakness, and failure is expected to occur at the weakest point at the bottom of...

Jan 1, 1955

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

By P R. G Milne

A risk-based approach to optimising pit wall slope angles was trialled in the design of a 60m deep open pit in extremely weathered and distinctly weathered materials in the Kalgoorlie area. The pit used for this approach was Stage 1 of a three-stage open pit project. The Stage 3 pit will require long term stability, as it will contain the portal for a long life underground project. Information from failures induced by steeper wall angles used in the Stage 1 pit would be valuable in predicting and preventing long-term stability issues in Stage 3. In this approach, the pit wall slopes are based not on the normal factors of safety, but on the assessment of the probability of failure and the direct and indirect costs of dealing with the failure when it occurs. In this example, the benefits and risks of adopting steeper wall angles were compared in a series of graphs. These charted the increasing probability of failure and simultaneous decreasing factors of safety with increasing pit wall slope, and the range in the possible volumes of circular failures for increasing wall angles. These were brought together in a graph showing the potential excavation savings (in BCM) and the probable cost of a failure (probability of failure times the probable volume of the failure). The resulting pit design was based on the project Mining EngineerÆs semi-quantitative assessment of where and when a higher risk of failure was acceptable and where it was not acceptable as it may have unduly affected the integrity of haul roads or production. The design incorporated wider than normal berm widths to accommodate anticipated failures and to enable modification of the wall configuration if required. Several re-designs were required during the life of the project in response to aggressively induced failures. It is considered that this risk-based approach provides a practical route to optimal pit design and operation but it requires an experienced, dedicated and efficient mining team for it to be implemented with benefit.

Jan 1, 2003

By Sandenbergh RF

The debate on the mechanism of adsorption of gold and silver di-cyanide onto activated carbon could be divided into two schools of thought. On the one hand, it has been proposed that the combined effects of electrostatic and chemical interaction between the activated carbon surface and adsorbing gold di-cyanide anion results in the adsorption of the latter. On the other hand the `ion-pair' adsorption reaction mechanism has been vigorously advocated as the dominant mechanism responsible for the adsorption of gold di-cyanide onto activated carbon. It is maintained that gold is adsorbed onto the carbon surface as the neutral ion-pair [M"+][Au(CN)z ]". Adsorption is viewed as the result of mainly the chemical interaction while electrostatic interactions are neglected. The validity of the `ion-pair' adsorption mechanism may be challenged on a number of counts. However, the alternative mechanism (based on aqueous surface chemistry principles) has not gained general acceptance yet, because it has not been applied widely enough to explain the different adsorption phenomena associated with gold di-cyanide on activated carbon. In the present study the case in favour of an adsorption mechanism based on general aqueous surface chemistry principles is presented. A model framework is developed for the adsorption reaction mechanism of gold di-cyanide onto activated carbon which incorporates the effects of chemical and electrostatic interactions between the dissolved species, the aqueous solution and the carbon surface. This model is then employed to explain a wide variety of reported adsorption phenomena for gold di-cyanide on activated carbon, such as the effects of pH, the adsorption of different metal cyano complexes, ionic strength, and type and concentration of cations in solution. In addition the effects of cyanide and dissolved oxygen concentration were investigated. No ready explanation, in terms of aqueous surface chemistry principles, is yet available for the switch in adsorption behaviour that agrees with ion exchange to ion-pair adsorption with increasing ionic strength.

Jan 1, 1997

By Wetzeil N

High ambient temperatures combined with high surface humidity in the north of Australia and, in particular, the northern areas of the Northern Territory can make underground workplaces relatively inhospitable at certain times of the year. . Woodcutters' silver/lead/zinc mine, situated some 80 km south of Darwin, would be the most northerly underground operation of any significance in Australia. As such, during the build up to the wet season, it has a particular problem of ventilating a deep underground mine with already high dry and wet bulb temperatures at the surface. The Mine Management Act and Regulations mention only that workplaces shall be 'in a fit state for a person to work in or occupy'. Woodcutters therefore set in progress a Heat Stress Program to endeavour to set standards which would be more measurable and justifiable. The aim of the program was to compile a record of ambient atmospheric conditions in the working areas such that areas and/or work activities generating high ambient temperatures and humidities could be identified, quantified and qualified. Once the analysis stage of this program was completed, Woodcutters compiled a set of recommendations for the continued monitoring for, and control of, heat stress conditions to ensure that no underground employee was placed at risk from 'heat stress'. These recommendations are discussed in this paper.

Jan 1, 1994

Most of the Ta-Nb ores in China occur in altered granites, and Ta-Nb minerals occur in these granites as accessory minerals. This type of Ta-Nb ores are characterised by whole mineralised granite mass, large reserves, low grade of tantalum and niobium, less economic minerals, complex mineralogy, difficulty in separation and concentration of Ta-Nb minerals and high operating cost of ore dressing. The Ta-Nb ore presented in this paper is a low-grade Ta-Nb ore occurring in altered granite in Jiangxi province. It has large reserves, with the grade of Ta2O5 0.013 per cent and Nb2O5 0.023 per cent. The process mineralogy study carried out by the authors determined ore mineralogy and ascertained occurrence of Nb and Ta and their mineral processing characteristics. The results are used as the guide for developing the optimum mineral processing flow sheet. The results also indicated that this type of Ta-Nb ore contains a high content of Li, K and Na, a low content of deleterious impurity Fe, and the tailings can be used as feed for glass and ceramic materials. This study provided important mineralogy information for exploiting and utilising low-grade Ta-Nb ore resources, developing a mineral processing flow sheet and further utilising the tailings.

Jan 1, 2008

Because of the work of the pioneers of sampling theory, we know the principles, test work and equations to use to design sampling systems to meet targets for precision and accuracy. However, we do not see such æproperÆ systems deployed everywhere a sample is obtained around mineral processing plants. In many cases, we do not have solutions that satisfy all of the theoretical, economic and practical considerations. There are some well-known problems, such as high-volume streams with wide size distributions combined with a sparse valuable component that is heterogeneously distributed (such as gold ore SAG mill feeds). However, other difficult sampling issues are common, such as streams which vary widely over a day in flow rate and slurry density (many flotation concentrates), and loaded CIP carbon on transfer to elution. Inventory measurement issues abound, especially for leaching operations where daily inventory change is significant for metallurgical accounting. The result is that operators realise that although they issue reports daily, they do not know what is actually going on in their plant on a daily basis with sufficient confidence to quickly diagnose problems or confidently predict the benefits of potential enhancements. The industry needs practical and economic solutions that can be awarded the ætheoretically correct samplerÆ tick in order to better understand and optimise their processes.

Jan 1, 2008

Australian contract mining as it is known today had its origins in the early-1980s. Before this time there were numerous examples of underground mine development, and specifically shaft sinking being carried out by contractors. However, these were typically international contracting companies who came to Australia for specific projects. Growth in the underground mining industry in the 1980s opened up the opportunity for contractors. Mine owners had a need for contractors who could bring technical and operational capabilities to a project combined with capital in the form of equipment. In the early years the contracting industry was dominated by smaller players who focussed on mine development. The relationship between mine owner and contractor was loose and typically contract documents were rarely referred to. Through the 1980s and 1990s the underground contracting industry in Australia grew to where today there are over 20 underground contracting companies operating in an industry with an estimated annual value in excess of $1 billion. Of these 20 companies approximately five dominate with annual turnovers exceeding $100 million. Underground contractors now provide all facets of underground mining including development and production. Over the last 20 years the underground contracting industry has been able to consistently lower costs to mine owners through a combination of:equipment productivity, labour productivity, and technical innovation.

Jan 1, 2002

Asian countries are now facing very crucial aspects of urban living under the recession of the economy. The current situation is such that those hard aspects may make the living standards worse and worse in the next century, unless proper measures are taken on the infrastructure for urban lives. More than half of the population in Asian countries are now living in cities. Nowadays, the socio-economic development of the Asian countries has been closely linked to the development of world economy because of the border-less economy system. The population inflow to big cities is inevitable as the Asian countries step into an industrialised economy. Such a tendency will be further accelerated when Asia becomes a centre of financial business in the 21st century. The government of any country has realised the situation very well. The United Nations has established a specific agency to solve the problems caused by the rapid urbanisation. This global agency for urbanisation is named United Nations Center for Human Settlement and it is so called Habitat. There are three Habitat offices in the world, Nairobi in Kenya, Santiago in Chile and Fukuoka in Japan. The activities of Habitat offices cover a wide field of issues such as housing, urban development, infrastructure and environment, etc. Habitat Fukuoka Office is serving Asia and Pacific in co-operation with the government offices concerned.

Jan 1, 1999

This paper considers the standard of ore reserve assessments required by lenders when presented to support requests for project based loans. The way lenders use this information to structure a suitable financial package shows why ore reserves should be measured by industry set standards. This in turn raises questions concerning the assumptions used to derive mineable reserves from geological reserves. Consideration of the variety of related problems highlights the need for assessments to be defined according to acceptable standards. These should also address the suitability of the methodology to the assumed configuration of the orebody; the degree of variance and relaibility of estimates of grade and tonnage presented; and the estimation of probability that ore will in practice fall within the defined limits. In an increasingly international marketplace it is appropriate to compare Australian industry requirements to those of similar overseas industries, in this case the United States. Lenders would like to see that individuals responsible for the preparation of ore reserve estimates are certified on the basis of their skill and expereince by an industry body such as The AusIMM. The paper discusses how each of the parameters indicated above may impact upon a lender's assessment of the viability of a project. A number of practical examples are presented where inaccuracies or inadequacies in ore reserve information have led to reduced project performance.

Jan 1, 1987

By S Choy

Aquatic macroinvertebrates have been used as a monitoring tool for many years. They are ubiquitous and occupy a central role in the ecology of rivers. They are a key link in the aquatic food chain, forming a pathway between primary producers (such as algae and macrophytes) and predators (such as fish, platypus and birds), and some are sensitive to flow conditions, water quality and habitat condition. They are not very mobile and are good indicators of local impacts. As most aquatic macroinvertebrates are benthic, they are better able to integrate effects of changes in water quality, and habitat condition and structure. Their diversity is crucial to the maintenance of a balanced, functioning and healthy river ecosystem. Thus, data on benthic macroinvertebrate community structures can be used for predicting potential impact, assessing the extent of damage and for gauging recovery from damage. Over the past eight years, State agencies throughout Australia, through the National River Health Program have developed models (AusRivAS) to assess river health using macroinvertebrate communities. The Queensland Department of Natural Resources and Mines has sampled both macroinvertebrates and water quality throughout Queensland, including areas affected by mine discharges. This paper will assess results obtained from sampling in the Mt Morgan area to illustrate the usefulness of this method of river health assessment.

Jan 1, 2003

Coal mining in the Illawarra commenced in 1848. By the early twentieth century mining operations were spread over quite a distance along the coast centred on Wollongong. By this time there were already numerous tunnel mines and one shaft mine. Coal was first reported in Illawarra by Lieutenant Flinders on a voyage of exploration, southerly along the coast from Sydney in 1796. Because of the topography, particularly the escarpment and the narrowness of the coastal plain, access from Sydney was not easy by land and the normal access was by sea. It was not until some coastal areas had been developed for agricultural purposes that the mining of the seams on the South Coast commenced for the supp- ly of fuel. The most important mines in the early nineteenth century were Bulli and Osborne Wallsend. In general, coal was won from the tunnel mines and was transported directly, usually by tramway, to the nearest shipping point. Considerable hardship attended the earliest attempts at mining coal in regard to materials for mining and the way of life of the miners in the vicinity of the mines. With the growth of production and the installation of coke ovens at some mines the area, hitherto virgin bush- land, began to take on a more industrialised appearance. The mines were necessarily small,

Jan 1, 1976

Suppression of the explosion of the world population and the surprising increase of waste and emissions are major targets confronting mankind in this century. Recycling and waste minimisation are key words for sustainable development in a highly industrial society. The argument is really whether or not recycling done well is the solution to the environment problem for the following generation. If energy is not necessary in the recycling, all materials have to be recycled. The greatest interest among the environmental issues is the regulation of CO2 gas emission. It must be recognised that it is not possible to completely renew expended energy. Some of the recycling systems currently used are thought to increase the load on the environment rather than to be beneficial. Although metal industries have consumed tremendous amount of energy and discharged a large quantity of CO2 and solid waste, the metals have supported a high quality of life. The metal production industries such as the iron and steel industry and the non-ferrous metals industry can work well recycling of not only metals but also other materials without consuming more energy. Waste plastics, for example, are use as a reductant in a blast furnace. The role of metallurgical industry in the recycling-based society is introduced in the present paper to recognise how the metal industries can contribute recycling and waste minimisation.

Jan 1, 2002

The first introduction of automatic control systems for flotation occurred about fifteen years ago. The early control work coincided with the introduction of on-line assaying using XRF techniques. This OSA availability, coupled with the emergence of small digital computers suitable for process control in the late 1960-s, meant that the necessary process information and control hardware existed for flotation control experiments. A period of intensive research related to flotation control. ensued. A great deal of effort was devoted to the development of mathematical models of flotation. Plant experimentation sought to understand the effects of a range of flotation variables on the process. Finally, control loops were proposed and plant tested. An evolutionary pattern emerges when the range of flotation control installations is examined. The earliest systems had as objectives process stabilisation using reagent control. There were also some early attempts at flotation optimisation procedures, again using reagent variation. Current work is still associated with the same objectives. One of the difficulties with flotation control has been to recognise and define clear and precise control objectives. More emphasis is now placed on cleaner control which has the advantage that the objectives are usually well defined. A number of flotation control systems which cover a range of control system types is discussed. Based on this accumulated experience,a list of good and bad practice in flotation control is Proposed.

Jan 1, 1983

By K Biegaj

During the author’s 25+ year career in mine management in various parts of the world (mostly in Australia), the author has been privileged to live and work in mining towns (not FIFO) for more than 20 years. And has personally observed other people from the mining industry carrying out work at home in an unsafe manner, eg pushing lawn mowers whilst wearing thongs or performing electrical jobs whilst standing on aluminium ladders, as well as many others. It is common that injuries sustained at home whilst on break are not reported upon arrival back on a mine site. A large number of compensation claims for injuries at work, which in fact had been sustained at home, come at substantial extra costs to mining companies.

May 5, 2022

Does coal mining get enough out of its people?. In a number of cases, Yes. Several companies have rethought their management systems and accordingly are improving their utilisation of people to improve productivity. For some, capital and technology are the panacea for improved productivity and lower costs. Computerised mine planning, improved beneficiation processes, heftier longwall equipment, bigger trucks and shovels and upgraded coal clearance systems are expected to provide the answers.Whilst these factors are important they only contribute to part of the productive potential of a mining operation. Production flexibility provided by recent Industry award changes has brought about increases in total output. However, these improvements have not been matched by corresponding decreases in the unit cost of production.

Jan 1, 1991

In the late-1990s, and into the 2000s, many industries, including the mining industry, have seen significant transaction activity by way of acquisitions, floats, joint ventures and major capital projects. The fundamental financial trends are two-fold. First and foremost, a high level of transaction activity within the industry and secondly, the recently introduced requirement for corporate governance standards, have placed increasing pressure on the directors of mining companies. This paper will deal with specifically corporate governance implications of any large capital investment transaction and the associated impact on the mining industry. To provide the framework for this paper, I have looked at a number of recent transactions as well as corporate governance recommendations from the ASX and the HIH Royal Commission.

Jan 1, 2003

By Burgess J

Present practice of lead-zinc flotation at North Broken Hill Limited is described and factors influencing plant objectives and performance discussed. Mineralogical examination of final flot- ation products showed mineral liberation to be 94T complete and size by size metal recovery tables indicated a need for finer grinding to improve lead and silver recovery, but coarser grinding to improve zinc recovery. A steady grinding circuit, at constant ball mill power and cyclone overflow pulp density, is found desirable for satisfactory flotation circuit operation because instabil- ity in the grinding circuit inevitably leads to flotation instability and as a consequence less than optimal flotation operation. Remov- al of the variable lead flotation middling product from the grinding circuit decreased grinding instability.

Jan 1, 1978