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By Read T. A

PART 1The quantity of dust present and the methods used for suppression of dust in metalliferous mines has, in recent years, received considerable attention from mining engmeers in various parts of the world. Shortly after the publication of the General Report of the Miners' Phthisis Prevention Committee, South Africa, in 1916, the officers of the Broken Hill South Limited started investigations into the conditions of the dustiness of the air in the underground workings. As the methods used are not generally known in Australia, the writers are of the opinion that the present is an opportune time to place them before members of the Institute. A large amount of the subject matter of this paper has been drawn from the 1916 and 1919 reports of the Miners' Phthisis Prevention Committee, South Africa, the paper of Mr. Innes published in "The Chemical, Metallurgical and Mining Society of South Mrica"; also various articles appearing in the Journal of Industrial Hygiene, and the American Journal of Public Health. A great deal of research work into the cause, prevention and estimation of mine dust has been made by the Miners' Phthisis Prevention Committee of South Africa, and officials of the United States Bureau of Mines. The writers considered it advisable to begin the investigation at the South Mine with apparatus and methods developed by the South African Committee.Through the Australian agent of the Cape Explosives Company, inquiries were made preliminary to procuring the necessary apparatus for the determination of dust, from South Africa. The writers then learned that the older gravimetric method used by the Phthisis Prevention Committee was likely to be superseded by the konimeter...

Jan 1, 1922

By M P. Simpson

Forty one whole rock samples from the Gold Cross low-sulfidation epithermal Au-Ag deposit have d18O values that range from 4.4 to 9.3 per mil, with an average value of 7.0 per mil. Unaltered and weakly altered rocks have d18O values greater than eight per mil, and the orebody is surrounded by samples that are depleted in 18O. A strongly silicified sample adjacent to the Empire Vein System has a d18O value of 9.0 per mil, similar to previously reported analyses of vein quartz (7.0 to 11.7ë, average 9.4ë). This suggests that, in detail, Golden Cross may have a zone of 18O-enriched wall rocks in the core of the deposit, adjacent to the main underground veins. Although some workers have suggested that stable isotope geochemistry may provide useful information for epithermal mineral deposit exploration, at Golden Cross this is not the case. Alteration minerals, major elements and trace elements all define larger, less ambiguous halos than the zone of 18O-depleted wall rocks.

Jan 1, 2001

The Devonian Mount Morgan gold-copper deposit was situated on the western margin of the Calliope Volcanic Are assemblage, in the northern New England Orogen. Recorded production from commencement of mining in 1882 to mine closure in 1989 stand

Jan 1, 1994

By Knijnikov M, Cameron D

Coal Quality management and the control of the flow of coal through complex mining preparation and transport phases of standard mining operations has assumed greater importance over recent years.

Jan 1, 1998

By G Liu

Seventy-nine gold deposits and prospects have been discovered in theJiamusi region of northeast China, and constitute one of the most important gold metallogenic belts in China. All these endogenic gold occurrences can be subdivided into three main deposit types: 1. porphyry related; 2. metamorphic-intrusive hosted, and 3. sediment-hosted deposit.   The first two types of gold deposit are spatially and temporally related to Mesozoic Yanshanian granitoid intrusions with hydrothermal activity channelled along crustal-scale fissures. The ultimate cause of the Yanshanian magmatism is considered to be the subduction of Pacific oceanic lithosphere beneath the Eurasian continent. In contrast, the chemical sediment-hosted deposit is typified by the Dongfengshan gold deposit, and genetically related to Proterozoic sedimentation and Mesozoic igneous activities.

Jan 1, 1995

By O K. Paki

A 14/12 millMAXTM pump was installed in the SAG1 grinding circuit as a trial replacement for the existing 12/10 Warman for performance comparison and in an attempt to overcome process difficulties. Krebs Engineers have developed the millMAXTM pump wet end to adapt to a variety of power frames. This system has been developed specifically for coarse material contained in mill discharge. SAG1 discharge screen undersize with a top size of 10 mm is collected in a flat bottom sump. Two 12/10 Warman pumps located on the same side of the sump, pump the screen undersize at 50 to 65 per cent solids to a distributor box which splits into two separate ball mill circuit sumps. One pump is installed towards the screen feed, while the other is towards the screen oversize discharge. The pump located towards the screen oversize discharge is prone to continual operating problems including pump bogging, high impeller and casing wear, and has consequently restricted SAG mill throughput. To rectify this pumping problem, it was decided to change-out the wet end of this pump with a millMAXTM. The design of the new pump enabled the wet end only to be retrofitted to the existing Warman pump frame, thus reducing change-over time. This was undertaken in the workshop under the supervision of a company representative where the pump, complete with bearing frame, new wet end, motor and base frame, was assembled. After installation of the millMAXTM pump during a SAG mill shutdown, performance indicators including motor power draw, sump level, and pump discharge pressure have been monitored. The trends indicate an increase in discharge pressure, low sump level, and low motor power draw. With the improved pumping efficiency there has been minimal pump bogging and no consequent SAG mill throughput restrictions. Pump wear rate has also decreased.

Jan 1, 2000

By Arit I, Adisoma G

General Limit Equilibrium Method (GLE) and Janbu's Generalised Procedure of Slices (GPS) are two limit equilibrium methods in slope stability analysis which satisfy all equilibrium conditions. Numerical difficulties associated with these metho

Jan 1, 1998

Validation and Simulation of Optimised Compressive Crushing Ores and aggregates are used in countless applications all around in the society. The frequent and escalating usage of these natural resources requires efforts aimed at not only making do with what is available, but also undertaking actions to improve the production yield and the processes involved. This strive to improve the performance and efficiency of existing crushers and crushing processes has brought about research concerning optimisation of crushing plants as well as theoretical optimisation of crushing. Previous work shows that different applications and different materials require different compressive crushing in order to accomplish a theoretically optimal size distribution. These optimisation results, obtained by genetic evolutionary algorithms and evaluated with so called fitness functions, convey the theoretically optimal number of compressions and their corresponding compression ratios. Presented in this paper are thus some laboratory crushing tests, which are conducted in order to validate a set of previously optimised crushing sequences. More specifically, interparticle crushing sequences are carried out in a Piston-die testing equipment, where samples are sieved between each compression. The subsequent analysis of these results shows good correlation with model predictions, which combined with a comparative study between presented optimisation results and measured data from a real crusher indicate a significant potential for improvement. However, before redesigning crushers according to what is theoretically optimal, the resulting impact as well as the effects on the outcome of a crushing plant must be examined. Crushing plant simulations using the software PlantDesigner« are consequently performed. Models of existing crushers are altered, resulting in changed particle size distributions from some of the crushers in a crushing plant. Thence, it is concluded that significant gains can be made in terms of capacity, process yield and energy consumption.

Sep 13, 2010

By McIlveen GR

The water pollution hazard posed by the derelict Conrad mine site, to the water and associated stream sediment of Borah and Maids Creeks and the nearby Copeton Dam storage, has been assessed. Mine water, tailings and tailings dump leachate have polluted water and stream sediments in Borah Creek downstream of the mine site. Acidity, arsenic, copper, lead, iron, silver and zinc are the principal pollutants. Under dry and low flow conditions, mine water was found to be the dominant polluting source, however, leachate and run-off from tailings dumps were also significant under and following wet conditions. Soluble arsenic, lead, iron and silver species in mine water and leachate were found to be rapidly incorporated into sediments, but acidity, copper, and zinc persisted in the creek water. Under low flow conditions, the water of Maids Creek is polluted with copper and zinc (up to 4.4 and 34 mg/l for copper and zinc respectively) and the pH is decreased (from pH 5 - 7 to pH 3 - 6) by entry of Borah Creek water. Values found in Maids Creek were variable and related to flow regime and distance downstream from Borah Creek confluence. Water in Copeton Dam storage, having a much larger volume of water with a higher bicarbonate buffering capacity (50mg/l versus 15mg/1), is not affected by entry of Maids Creek water. Polluted sediment from Borah Creek has contaminated Maids Creek for 2km downstream to Copeton Dam storage. Stream sediment downstream of the Borah Creek confluence, contains up to 1.0% As and 1.4% Pb in the less than 200 micron size fraction. Under high flow conditions, arsenic was found to be moved out from the mine site as insoluble species, associated with suspended sediment in Run-off.

Jan 1, 1988

Mining has long been an important activity for the people of Australia. The Aboriginals used rocks and minerals in their culture many thousand years before European settlement. It was not until 1840 that silver-lead ore was discovered in the Mount Lofty Ranges, and developed as Australia's first metalliferous mine.

Jan 1, 1995

By Reifenstein A

ACIRL's petrographers apply microscopic techniques to coal exploration, production, preparation and processing problems and research investigations as well as provide a commercial service for quality control of export coal shipments. This paper describes a number of case studies of applications of petrography to coal industry problems and coal research, including

Jan 1, 1989

Bioleaching of Weathered Saprolite - Heavy Metal Adaptation Mechanisms of Aspergillus foetidus Nickel laterite ores remain important to the future supply of Ni and Co as they contain the bulk of known nickel and cobalt reserves (80 per cent and 90 - 95 per cent respectively). Current commercial extractions of Ni and Co from nickel laterite ores are energy intensive and operational costs are high. Microbial leaching of oxide ores has the potential to offer a much needed step-change in the technology for processing laterite ores. Biological leaching of low-grade nickel laterite is based on a non-traditional leaching of oxide minerals using heterotrophic micro-organisms. The organisms solubilise metals by excreting organic acids; these acids then form complexes with heavy metals. Optimisation of the process in in-situ application, however, has been hampered by the toxicity of the heavy metals that are being leached by the organisms. Our recent study has shown that organisms are able to develop tolerance towards heavy metals by adaptation. This study examined the extracellular metal detoxification mechanisms of A. foetidus in 0.2 per cent (wt/v) to 0.7 per cent (wt/v) of weathered saprolite ore. To support our analysis, FTIR, CHNS and microscopy were used to confirm the participation of specific functional groups in the extracellular detoxification process.

Sep 13, 2010

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

During the past Two years in reef gold mining, "indicators" have received great attention at the hands at the Victorian gold seekers. Many years ago, what was caned the" indicator lode," was struck in Ballarat East, on the course of which extremely rich deposits of gold were discovered but as to its being a .qeneral experience in reefs or leaders no one ever dreamed. Now, however, we find that these "indicators" are frequently to be met with, though they differ very much in different localities, making it, therefore, a difficult matter for other than a careful minel' to follow them. The necessity of following "indicators" for the purpose of developing gold is now recognized, and the policy of following them up has been attended with much success in this field. In the case of Messrs Shaw and Sons, at Wedderburn, those gentlemen began to work on an "indicator" here five years ago, and immediately thereafter more by accident than anything else they being at that time inexperienced as regards "indicators " came upon gold bearing quartz, which continued payable so long as the" indicator" aud the stone were in conjunction with each other, but as soon as they parted company the stone ceasedto be of any value then, by following the" indicator," as the latter intersected fresh bodies of stone they proved again more or less payable, until a fortnight or so ago the Messrs. Shaw turned out 4 tons of stone, which yielded £1,825, with also profitable workingup to the present moment. Where they are now working is a mile north of their original find thus proving that "indicators" travel considerable distances and have something to do with the gold deposits found in reefs. On the direct course of Shaw's "indicator," as high as hundreds of ozs to the ton was obtained from the stone but, just a few inches from either side in the same" leader," not a colour could be got. Whatever the cause-whether by electricity or some unknown force in nature-the gold is found on the course of these" indicators" and nowhere else, and-as each of the Victorian Government Geologists admit-their value to the gold-seeker as a means of leading to' gold cannot be over-estimated.

By R Morrison, P Owen

Particle breakage is an essential part of mineral processing. The aim is to reduce run of mine mineral ore to an optimal size for liberating target minerals and for subsequent recovery by separation processes such as flotation. This size reduction is typically accomplished in a series of stages in a grinding circuit tailored to the properties of the particular mine ore. Commonly this involves two or more classes of equipment starting with crushers, followed by SAG mills and then sometimes ball mills. Occasionally, high pressure grinding rolls or other novel devices are substituted. Broadly, energy consumption increases and energy efficiency decreases with the fineness of the material produced by each piece of equipment. For many operations, up to 50 or 60 per cent of total greenhouse gas emissions from a plant arise from the operation of the comminution circuit with the majority produced by the finest grinding parts, such as the SAG and ball mills. Wear of mill liners and grinding media also add to greenhouse gas emissions generated by their manufacture. The need for continual cost reduction and increasing regulatory and social pressure relating to greenhouse emissions create a strong need for improvements in comminution energy efficiency. Traditional experimental and modelling approaches are not well placed to create the required insights into comminution fundamentals or facilitate radical step changes in performance. This paper discusses the role that advanced modelling (based on coupled DEM and CFD) can play in improving the energy efficiency and performance of existing mainstream grinding equipment and in the development of new ones with radically superior performance. Achieving this goal will also require an improved understanding of ore breakage and methods to include sufficiently realistic breakage models within the DEM models. Developmental issues for the modelling and the critical need for validation of the advanced model features are highlighted.

Jan 1, 2004

Disasters are often tragic outcomes of high-risk technologies such as mines. In Australia, more mines are being developed every day, and the risk of disasters is ever increasing. No matter how effective our conventional safety devices are, there is a form of accident that is inevitable. These relate to accidents that result from æinteracting failuresÆ in a way that could not be foreseen by the designers. In so-called ætightly coupled production systemsÆ (processes that happen very fast, such as on a high producing mine) the risk is even higher and our risk controls mostly introduce some sort of a technological fix. While we are at the one hand attempting to control the risk, we are also introducing another level of complexity. Are we really controlling the risk? This is one of the fundamental questions that will be addressed in this paper: Do we have the ability within the mining industry and other industries to effectively prevent these catastrophes, or are we, on the contrary, faced with an increasing risk as a result of increasing complexities of our technology, management systems and practices. This paper will contend that perceived improvement in risk control is an illusion of activity, and that the likelihood of mining catastrophes may be exponentially increasing. Although the paper focuses on the mining sector many aspects may be applicable across a range of industries. This paper will further contend that we are applying the right solutions to the wrong problems. Our focus is technological and procedural, while our problem is one of production cultures ripe for error and failure.

Jan 1, 1999

By Murdaugh W

The application of photogeological techniques and analysis of more advanced remote sensor images can be a cost and time effective tool in the search for desert placer gold deposits. Examples are given of regional analysis using standard false color composit Landsat images and conventional black and white aerial photography. The examples include identification of sites to sample to evaluate the pathways of .alluvial gold migration and identification of potential sites of concentration. The results of these studies developed an increased number of target areas and exploration in proceeding with promising results. In addition to the development of additional target concepts and identification of specific target areas data useful to evaluation of mineability can also be obtained from photogeological investigation. Some indication at least can be obtained of the existence of duricrusts and salines that may hamper mining. Identification of possible sources of water is another important task in the desert environment. In addition indications of the clay content of the material to be worked is very important because of its economic impact on operational costs and overall recovery. The application of photogeology to these questions is discussed.

Jan 1, 1988

By E Kunz

Decreasing the gas content in the worked seam by degassing before the start of winning has proven its worth in some areas of German hard coal mines. On the one hand, it removes the risk of gas/coal outbursts and on the other hand it reduces the gas inflow into the longwall. The underground experiences of the last 30 years have led to a æhit listÆ of coal seams with respect to their suitability to predegassing. Trials in the DMT laboratory and also results gained in the deposit show that the suitability of a seam for predegassing depends on its rank. In seams with volatile matter of 20 - 30 per cent, high efficiency ratings are achieved as a rule, with lower ratings both in seams with lower and with higher content of volatile matter.If the rock pressure is unusually high, the efficiency rating of the predegassing is lower, even in seams which would normally be suitable for this process. Under unfavourable conditions, for example below or above residual pillars, in-seam boreholes cannot be drilled successfully and the method is not practical. But if the worked seam was already stress relieved, the predegassing has an optimal efficiency. Latest investigations show that the distance between the in-seam boreholes can be extended. But in that case, the time necessary to reach the same reduction of the gas content increases considerably.

Jan 1, 2005

Optical sensors have emerged during the telecom boom in the late 1900s, due to the availability to low-cost telecom-grade optical components. It's only after the telecom industry's fall in 2004 that optical sensors became sufficiently developed to be a viable technology for real-world applications. Geotechnical applications have long relied on electrical sensors such as thermocouples, strain, and the venerable vibrating wire to measure physical phenomena. Although these are well suited for a large variety of applications, electrical sensors cannot be used for all applications: these are vulnerable to noise, hazardous voltages and corrosion, limiting the environments in which they can be used. In addition, electrical wires can also become an issue when sensors require external excitation or are distant from the measurement system. Finally, changes in physical properties of electrical sensors and systems over time makes regular calibration a necessity - not easy to do when these are permanently mounted on structures. Optical sensing systems are non-conducting and use light to perform various measurements. There are several optical sensor technologies available, each with different strengths and weaknesses. In addition, there are different methods of interrogating optical sensors, each of which also present different strengths and weaknesses. To make matters worse, configuring the interrogation and scaling to physical units can also be challenging to the unprepared engineer. This paper will present a holistic view of optical sensing, presenting the different optical sensor technologies and interrogation techniques. Sample optical sensing systems will be revealed and top considerations for optical sensing will be presented.

Nov 25, 2010

Solid. dense, air-cooled slag can fulfil most, if not all, the functions of natural stone for civil engineering purposes. The value of pumice, also, has long been appreciated, and processes for the manufacture of similar synthetic material for light-weight concretes and insulating fills have been developed in past years.Foamed slag is, in effect, blast furnace pumice and is often referred to on the European continent as metallurgical pumice. It is made by the treatment of molten blast furnace slags with a critical quantity of water during which process the slag cools and expands into a sponge-like mass. The connection between foamed slag and air-cooled slag is also considered and a basis for density control given.All blast furnace slag cannot be foamed to give a product which would comply with B.S.S.877; 1939 Foamed Blast Furnace Slag. A large proportion of the total output of molten slag lacks the necessary inherent properties. This investigation attempts to discover the conditions necessary for the production of foamed slag capable of meeting the British specification.EARLIER WORKIt was generally accepted (Parker, 1951; Gallai-Hatchard, 1955) that the spongy structure of foamed slag was caused mechanically by steam trapped in the slag when it was poured into water. It was assumed that slags which would not foam would not trap steam, because their viscosities and surface tensions were unsatisfactory, on account of temperature and/or composition. The earliest systematic investigation was made by Frisak (1923) who attempted to establish a limiting chemical composition for foamable slags. He decided that foamable slags covered most blast furnace slag compositions on the basis of silica, alumina, and lime, and further "that the replacement of lime by magnesia up to 15 per cent has no noteworthy effect on foamability, that moderate quantities of alkalis are not deleterious, that sulphur raises the foamability and that MnO is only deleterious in the presence of 1...

Jan 1, 1963