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An investigation was made into the mineralogical characteristics of the upper portions of the 650 and 750 copper lodes. The investigation was based on a comprehensive suite of geological specimens representing all types of mineralization encountered during mining until the end of 1954 and the chief aims of the investigation were to determine (a) the minerals present and their textures and associations, (b) the paragenetic sequence of deposition of minerals in the orebodies, (c) significant changes, if any, which could be found in the orebodies with depth, and (d) the nature and mode of occurrence of nickel in the ore. The general structure of the orebodies is outlined and their mineral composition given. 10 textures exhibited by the ore minerals are described and a paragenetic sequence of events in the formation of the copper orebodies is outlined. No decrease in the complexity of the sulphide mineral textures with depth could be seen and no evidence was found to suggest that the tenor of the ore would decrease with depth although some factors which may eventually limit the extent of the orebodies are noted. The mode of occurrence of minor elements in the orebodies is described. Notes on the occurrence of pyrite, aikinite and berthierite in the orebodies is given and the orebodies are considered to be identified with LiIidgren's mesothermal type of sulphide ore deposit in which considerable replacement of older by younger generations of sulphide minerals occurred.INTRODUCTIONA mineragraphic study was made by Stillwell and Edwards (1945) of a suite of specimens submitted by Mount Isa Mines Limited from the Mount Isa Black Star copper orebodies with a view to determining 1. the nature, extent and association of arsenic, antimonyand bismuth minerals, 2. the mode of occurrence of silver and 3. whether galena and sphalerite occurred in minute forms and below the sizes readily observed in hand specimens.

Jan 1, 1961

The working of alluvial deposits has from all times been a popular form of mining, not only from the simplieity of its operations, but also, in its more primitive stages, from the possibility of carrying it on without large capital, without skilled lahour, expensive plant, long terms of preparatory work, or, in fact, any other requisite than a shovel, a dish, and a stout pair of arms. It is possibly one of the oldest industries, and probably, also, it has been one of the most profitable.In tbe Australian States the happy days of rid alluvial deposits, when gold was to be hltd for the shovelling, are now almost over. The lust for gold has caused almost every corner of the world to be ransacked, and the more easily earned wealth to he exhausted: for the most part there remain now those deposits only which are too poor to be profitably worked by means of the implements and methods of old times. But, though the deposits have become poorer, the keen inventiveness of man has devised means whereby such large quantIties can be treated at a cost so low that he can still make a profit out of them. In this article, out of the many means devised, three only will be referred to-viz., hydraulic sluicing, bucket dredging, and hydraulic dredging. All mining may be divided into three principal operations-1st, the breaking down and conveying of the ground to where it is to be treated for the recovery of the metallic values, 2nd, the treatment of the material for the recovery of those values; and, 3rd) the removal of the worthless material or tailings. In all mining the object is to effect these three processes for the least expenditure of money commensurate with the highest degree of efficiency.

Jan 1, 1907

By U Rehm

The biggest hard rock double-shield tunnel boring machine (TBM) in the world, with a diameter of 12.4 m, is currently excavating the North-South Bypass, which includes a crossing under the Brisbane River, Brisbane, Australia, to relieve the often congested road traffic in the city centre. Ten years ago a 10.7 m Mixshield giant helped to handle the Olympic Games in Sydney linking the airport with the city centre for an improved transportation of fascinated visitors. In Shanghai, currently the biggest TBM in the world with 15.43 m diameter presents excellent performance rates; and in Paris a convertible Mixshield could be quickly changed from earth pressure balanced (EPB) to slurry type in order to handle the very heterogeneous ground conditions. In Madrid a 15.2 m EPB giant finished its tunnel job four months ahead of schedule. Large-scale TBMs have proved their economic and innovative potential to create the current and future underground architecture of mega-cities. TBM technology has made further large innovative steps in the last decade. State-of-the-art is a TBM for very heterogeneous ground conditions comprising hard and soft rock with additional high groundwater pressure. The machine concept is adapted to the various ground conditions and allows for a quick and flexible application. Ground treatment by means of additives developed to a helpful tool in this connection. To meet the special challenges of urban tunnel projects of nowadays it is of very high importance, beside applying highest developed technology of TBM, to have a comprehensive technical support during the project phase and to develop positive relationships between all participants of the project which last longer than only for one project.

Jan 1, 2008

By L Reynolds

The portable infrared mineral analyser (PIMA) was trialled to determine the extent and intensity of any hydrothermal alteration halo associated with gold mineralisation in the Hyde-Macraes Shear Zone (HMSZ) of the Otago Schist.   Twelve diamond drillholes through the HMSZ were analysed with the PIMA at a sample spacing of 1 m. The drillholes were selected on two traverses along the line of strike and down-dip of the mineralisation in and around Panel 2 of the Frasers underground development.   The study showed that the Hangingwall shear of the HMSZ has a more distinctive infrared signature in intersections with high grades. The Hangingwall shear in these drill holes is defined by a shift in the wavelength of the Al-OH absorption feature from ~2220 nm to <2210 nm. This shift is attributed to a change in the mineralogy from phengite to muscovite. Overprinting this trend in some of the drillholes is the presence of the 2210 nm Al-OH absorption feature, ascribed to kaolinite. Kaolinite also tends to be present in numerous other regions of the schist above the Hangingwall shear associated with steeply dipping faults and foliation parallel joints. In drill holes with low grades the Hangingwall shear does not exhibit any obvious infrared signature.   At the scale of study, the PIMA does not provide evidence for an alteration halo associated with hydrothermal mineralisation above the Hangingwall shear. Possible tectonic movement may have displaced any alteration halo that once existed, away from the zone of mineralisation. For this reason, PIMA apparently cannot be used for predicting the location of the Hangingwall shear during exploration drilling. However, the study did show that the PIMA could define the Hangingwall shear when the rocks were sufficiently altered and mineralised.

Jan 1, 2007

By V Salamakha, K Tang, G Si, J Oh, X Wu, Z Yu

The development of machine learning (ML) algorithms has led to promising advances in lithology classification from geophysical logs, which is indispensable in various underground engineering applications. Due to the resolution and availability of logging data, ML models can recognise lithology change in a definitive form at a fine scale (0.01 m). While the results from previous models indicated promising performance in the classification, the robust capability of generalising lithology prediction to unseen data may not be true for those models due to: (1) data bias caused by borehole selections, and (2) logging data mismatches among boreholes. To this end, this paper aims to investigate the generalisability of ML models and seek potential improvements. Four ML models were selected to be trained on single reference boreholes to test the other (as unseen) in the same region, which includes Support Vector Classifier (SVC), Random Forest (RF), eXtreme Gradient Boosting (XGBoost) and Residual Neural Network (ResNet10). The data set involves 11 boreholes from a coalmine in north-western Bowen Basin (Queensland, Australia): density, gamma ray, neutron, and sonic logs are selected as inputs. Additionally, a data adaptation method is applied for better generalisability. The results show that there is an accuracy trade-off between the same borehole and unseen boreholes across the models. It also indicates a 16–43 per cent reduction in model performance when generalising the predictions (in marco-F1 score), while the adapted data sets can contribute to a around 12 per cent improvement. This study provides a fundamental understanding of the model generalisability when using a single borehole, essential for further correlating boreholes for regional lithology classification; the adaptation method can improve the generalised accuracy, and reduces the labour to label lithology, which facilitates the identification of gas storage mechanisms, geological/geophysical modelling, and stratigraphic analysis.

Sep 1, 2024

By Howard G. L

The gold treatment plant of Great Western Consolidated N.L. is at Bullfinch, Western Australia, 22 miles north of Southern Cross, which is 100 miles west of Kalgoorlie. A railway to Southern Cross connects the mine with the main Perth-Kalgoorlie line.The plant, which commenced operations on the 31st October, 1952, was, designed by Messrs. Alex: Stewart & Co. in consultation with the technical staff of Western Mining Corporation Ltd. to treat 1,000 long tons a day, made up of approximately equal parts of quarry oxidized ore and underground sulphide ore, by moderately coarse grinding (2-3 per cent plus 65 mesh Tyler) and straight cyanidation without straking. The design had to allow for future treatment of all sulphide ore at the rate of 40,000 tons per 28-day periodand to make provision for the possible later inclusion of preaeration treatment.The test work on .which design was based was done on representative development samples, the mine being divided into zones for this purpose, to check possible local variations from average treatment behaviour. Proposed mill feed mixtures were made up from time to time for complete ore dressing tests, which were conducted in the Western Mining Corporation laboratory at Kalgoorlie.The chief feature of the design was that the plant had to handle the extremes of very soft, poor settling and filtering oxidized ore and very hard, good settling and filtering sulphide ore. On one hand, crushers and mills had to be large enough to handle the sulphide ore and on the other, thickeners and filters had to be large enough to handle the oxidized ores.The design is marked by simplicity, the use of large units of equipment, and flexibility to cope with a variety of ores.

Jan 1, 1956

The subject of steel wire ropes covers such a wide range of points that it would be impossible to deal with it fully in one paper, and in view of the apparent scarcity of published information on the subject it is proposed in this paper to deal with those items which should give the mining engineer a better understanding of the basic factors which affect the design.selection, and use of ropes. The matter will be considered under the following headings:-1. Brief history of steel wire rope-making.2. Rope-making terms.3. Wire rope materials.4. Characteristics affecting economy, operating life, and serviceability of a rope.5. Properties of construction of rope, and stresses met with in wire ropes.6. Drum and sheave sizes and sheave bearing pressures.7. Storage, handling, and maintenance of ropes in service.8. Common factors affecting rope life, particularly winding and haulage ropes.9. Inspection of ropes.GENERALWire rope, which was invented for, and first applied to mine winding, has become an indispensable aUXiliary throughout the whole field of mining, be it for underground, open cut, or dredge work, as well as the requirements of transport and treatment of ores.Though wire ropes appear simple collections of wire and fibre, the demands made upon them are many, and the stresses and abuses to which they are exposed in service are varying, and often of serious dimensions.The exposition of these stresses and abuses, particularly dynamic stressing, corrosion, etc., all of which seriously affect the safety and economical life of the ropes, is often enough to frighten most practising mine staffs, who are aware that before the requirements of economic operation stands the still more important question of safety in mining.

Jan 1, 1947

Vatukoula, the Fijian equivalent of gold rock, is the name of the community embracing the gold mines owned and operated by Emperor Gold Mining Company Ltd., Loloma (Fiji) Gold Mines, N.L., and' Dolphin Mines Ltd. It is situated in the Tavua Goldfields approximately five miles from the northern coast of Viti Levu, the largest island of the Colony of Fiji.The climate is sub-tropical, there being a definite wet and dry season. The wet season is somewhat variable in length but usually extends from December to March, during which time most of the rainfall for the year is recorded.Although the average annual rainfall is 71 in., more than twice this amount has been recorded. Precipitation at the rate of 5 in. per hour is not uncommon and 15 in. of rain has been registered in 24 hours. The mining methods adopted, therefore, had to suit these wet conditions.The occurrence of gold in the Tavua area has been known since 1872, but it was not until 1932 that discoveries were made which led to the formation of the present operating companies. In 1934 the Emperor Gold Mining Company Ltd. commenced operations, followed in 1935 by the Loloma (Fiji) Gold Mines, N.L., and later by the Fiji Mines Development Ltd., now known as the Dolphin Mines Ltd. Up to the end of 1951 these three mines had produced 2,501,688 tons of ore from which 1,277,881 oz. of fine gold and 347,429oz. of silver were obtained, realizing in Fijian currency £13,025,153.The three mines are situated close togeth.er on contiguous mining leases, and, although under common management, are operated as separate en,tities. Since 1944 all the...

Jan 1, 1953

By C Zhang, I Canbulat, S Saydam, H Yu, H Chen

Natural rocks are frequently exposed to groundwater and complex geological conditions. Environments with water presence are more susceptible to chemical corrosion, which notably affects rock’s micro properties. Generally, the pH of acid mine drainage in hard rock mines can be low to 5, and the pH of quarrying waste deposits can be below 3. With the expanding scope of mining engineering in aquifers and salty areas, chemical corrosion can also caused by different types and concentrations of anions. The anions can significantly affect rock’s mechanical properties. Therefore, it is critical to emphasise the impact of anion and acid on the mechanical and micro characteristics of rock. This paper commences with an introduction to representative corrosive environments. Then the UCS tests are conducted on granite samples corroded by chloride ions and sulfate ions. Anion has negative effects on the strength of granite. The reason is that certain minerals can react and be dissolved by anions and hydrogen ions, such as Al2O3. Furthermore, the scanning electron microscope (SEM) shows that the roughness of the fracture surface increases with the anion concentration. The effect of acid is notably more pronounced than anion on the micro properties of granite. The initiated fissures and pores also increase with the concentration of SO42- and Cl- ions, which is the micro explanation for the impact of anion on rock strength and stability. Subsequently, the permeability of the granite specimens is tested. The reason that granite performs insensitivity to acid and anion is attributed to its low permeability and high content of inactive oxides, such as quartz. To summarise, anionic and acidic conditions can slightly deteriorate the mechanical and micro properties of granite. While SO42- demonstrates a higher level of corrosiveness on granite than Cl-.

Sep 1, 2024

By R J. Nicholson, J M. F Clout

As part of an overall strategy to make significant new technological advances for the sustainability of the mineral processing and related process industries CSIRO Minerals has developed a new dry separation device. It represents a technology breakthrough and has the potential to radically change the way in which dry particle size classification is achieved in the minerals industry. Conventional dry separation techniques have limited applications and often suffer from low productivity, high operating costs, low separation efficiency, the need for dust control and a lack of flexibility. In the absence of efficient dry techniques, wet processing is often used. The use of wet processing either requires the introduction of water into a separation process, which causes environmental concerns through the need for water supply and tailings dams or the use of æunfriendlyÆ chemicals for dense media separations that have considerable impact on handling and disposal. Wet processing also increases operating costs due to plant instability, materials handling, thickening, filtration and product drying. The new CSIRO technology exploits a combination of natural and applied forces to achieve specific particle motions that produce size separation. In doing so, many of the traditional shortcomings of dry separation have been overcome. The CSIRO Dry Particle Size Separator is ideally suited for dry size separation applications within the size range 1 mm to 30 ¦mfor moderate moisture levels (2 per cent), have low unit throughput, produce a fixed cut size and are therefore impractical where very high unit capacity and low operating costs are required. This paper presents a review of dry separation devices together with details of the new Dry Particle Size Separator and typical results for a number of materials, including iron ore and quarry dust.

Jan 1, 2002

By Krouse RH, Aleinikoff JN, Nokleberg WJ, Church SE, Newkirk SR

A belt of volcanogenic massive sulfide (VMS) deposits and occurrences extends for over 150 km along the southern margin of the Yukon-Tanana terrane in the eastern Alaska Range. The VMS bodies occur mainly in the Jarvis Creek Glacier subterrane (JCGS), one of the highest structural/ stratigraphic levels of the Yukon-Tanana terrane. The JCGS consists of a VMS--bearing metavolcanic rock member and a metasedimentary rock member. The VMS deposits and enclosing rocks exhibit two periods of regional metamorphism.From northwest to southeast, the major VMS districts are the Bonnifield, Hayes Glacier, McGinnis Glacier, and Delta districts. The Bonnifield, Hayes and McGinnis Glacier district sulfide bodies consist of pyrrhotite and lesser amounts of pyrite, chalcopyrite, with or without arsenopyrite, sphalerite and galena. The larger, 800 km Delta district deposits and occurrences contain variable amounts of pyrite and pyrrhotite and lesser amounts of primarily chalcopyrite, galena, sphalerite, and arsenopyrite.The sulfide accumulations are interpreted as Kuroko-like deposits that formed along the submarine volcanic part of a Devonian, continental-margin igneous arc. U-Pb isotopic data from zircons from the metavolcanic rocks indicate an age of about 370 Ma (Devonian). 207Pb/204Pb ratios for sulfides from the districts are similar and indicate lead was in part derived from first cycle sediments eroded largely from Precambrian crystalline rocks. 207Pb/204Pb ratios from feldspars in Devonian metavolcanic rocks are similar to those in sulfides, and indicate incorporation of radiogenic Precambrian lead into the Devonian magmas. A Precambrian crystalline source for quartz in metasedimentary rocks is indicated by 2.3 Ga old zircons. Common-lead isotope studies of igneous phenocrysts in metaigneous rocks and sulfides in volcanogenic massive sulfide deposits indicate a unique isotopic signature. The data permit an exotic origin of the Yukon-Tanana terrane with respect to North America.

Jan 1, 1990

The paper gives details of the performance of a 6-ft. by 6-ft. grate discharge ball mill which was converted into a rod mill of the overflow type and then into a grate discharge rod mill. Proposals for further alterations are outlined.INTRODUCTIONThe mill of King Island Scheelite (1947) Limited recovers scheelite by gravity methods.Crushed ore at the rate of 34 tons per hour is divided between two mills. (6 ft. by 6 ft. and 8 ft. by 6 ft. respectively), the mill discharges being pumped to a common distributor which feeds seven Hummer Screens. Each screen has three 4-ft. by 2-ft. Ton-cap sections and repulping compartments are provided. The screen oversize is returned to the mills whilst the screen undersize is finished grinding section product. A third (6 ft. by 6 ft.) mill regrinding the coarser table tailings also discharges into the common Hummer Screen Distributor.The screen undersize is pumped to a bowl classifier which separates at 200 mesh. The bowl classifier sands are treated on tables whilst the bowl classifier overflow, after thickening, is treated in the slime plant by flotation. The flotation concentrate is further concentrated on vanners and slime tables.A recovery of 80 per cent. is possible by tabling whereas only 50 per cent can be recovered in the slime section. The object of comminution is, therefore, to reduce all the new feed to less than a certain mesh (22 mesh Tyler) with the production of a minimum quantity of minus 200 mesh material. cheelite is, a very friable heavy mineral (Sp.Gr. 6'0) and is therefore susceptible to overgrinding. For the evaluation of grinding performance it is hence advisable...

Jan 1, 1955

By E de N, B H. Usher, F D. I Hodgson

Due to the haphazard application of static tests in South Africa, several methods and interpretations have been followed. This has resulted in confusion amongst practitioners and regulators in the use and validity of these methods. Research was done over a two-year period to define standardised methods and interpretation of results. This included laboratory testing and continuous consultation with all interested parties throughout the country. The research yielded a modified ABA, based on several existing methods. The methodology includes AP determination using hydrogen peroxide, and an analysis of the supernatant by ICP. This has the advantage of not only registering reactive sulfur, but also provides the NAG pH, that enhances the interpretation and QC of the tests. Analysis of the supernatant provides an indication of heavy metal solubilisation, should acid conditions arise. One hundred and seventeen samples were compared to Leco S analyses and provided a good correlation. The Leco values were slightly elevated due to the reporting of total S as opposed to æreactive SÆ. The NP method deviates from the usual methodology, in that H2SO4 is used (to provide a field analogy) and the fact that a 24-hour stabilisation period is allowed before back-titration. The latter modification appears to prevent psuedo-buffering by transient phases. These methods have also been tested for repeatability and prove to be robust. A very simple macro-driven spreadsheet, æABACUSÆ, was also developed. This spreadsheet allows the entry of basic data and provides a detailed interpretation and graphical display of typical ABA data. In cases where drill holes are used, the Pennsylvanian approach of volume calculation can also be done with ABACUS. The results of the research have been distributed to interested parties in South Africa and it is hoped that these methods and their application will find widespread acceptance.

Jan 1, 2003

About 74% of global seismic energy release occurs in the Circum-Pacific zone. Worldwide, about 71% of seismic energy release is in the form of shallow earthquakes, 27% as intermediate, and 2% as deep earthquakes. Seismic energy release is variable in time and has been shown to correlate with the amplitude of the Chandler wobble. It was high during the period 1949 to 1967, and is now at a rather low level, with the latest earthquake over M = 8.0 having taken place in Indonesia in 1971. The average worldwide recurrence rate for the expected largest magnitude earthquake (M "9.5) has been estimated as several tens of years, in marked contrast to the several tens of thousands to hundreds of thousands of years separating the largest volcanic eruptions. Geological studies are needed to establish reliable mean intervals between large earthquakes, and to detect the e;:istence of long-term fluctuations in the ste of occurrence. Seismic gaps have proved seful in static forecasting of large earthquakes, by identifying places where closer study of the variation with time of seismicity, deformation, and other parameters, may lead to the dynamic p_ediction of time, place and magnitude of earthquakes. The model of stress concentration at asperities explains the main features of seismicity in the Circum-Pacific. Slow earthquakes have been detected instrumentally, notably an event immediately preceding the 22 May 1960 Chile earthquake, the largest this century. It seems likely that this type of deformation may explain both instrumentally detected and macroscopically observed pre-seismic deformation, as well as unusual animal behaviour reported before some earthquakes. Seismic and volcanic events are interdependent, with large earthquakes commonly triggering eruptions. Melting of rock and intrusion of magma is likely to accompany many earthquakes.

Jan 1, 1987

By R Berthelsen

The Peak Gold Mines Pty Ltd (PGM) operations are located approximately 9 km south of Cobar, NSW. PGM currently mines and treats ore from three separate orebodies within 5 km of the original plant. Production from the original Peak orebody ceased in April 2002, with ore currently sourced from underground at New Occidental and Perseverance, while New Cobar supplies ore from an open cut mine. In March 2003, Wheaton Minerals Asia Pacific purchased the operation from Rio Tinto who operated the mine for around ten years. The Perseverance deposit is situated between 600 and 1000 m south of the Peak orebody. Access is via shaft from Peak to 630 m below surface and then by decline to the northern end of the deposit locally known as Zone A. Development of the resource commenced mid 2002 to set up for a long hole open stoping operation at 25 m level spacing. The first production stope was successfully brought on line December 2003. The Perseverance deposit is hosted by sediments and volcanics along the eastern margin of the Devonian Cobar basin and is one of many deposits with the Cobar Gold Field. The Cobar Gold Field has produced approximately 2.5 million ounces of gold since 1880. The Perseverance area had long been considered prospective due to the presence of old workings at the southern extensions of Peak line of lode. Significant mineralisation was first discovered at Perseverance in 1994 when PGM drilled a hole targeted 950 m below the historic workings. The target was based on an apparent plunge to the stratigraphic controls to the Peak Orebody. Subsequent exploration within and around the ægreaterÆ Perseverance area has been significantly aided through the use of downhole electro-magnetic surveys due to the close spatial association between gold and sulfide mineralisation.

Jan 1, 2004

In the years prior to the outbreak of war in 1939 Australia's production of copper had declined from a peak of about 80,000 tons in 1911-1915 to approximately 25,000 tons in 1939. This production met the need of the slowly growing national requirement and gave an excess for export. However, with the intensification of the war effort in 1942 due to the imminence of a Japanese invasion of this country, or at least a blockade of the sea lanes, it became necessary to expand production of armaments, and consequently the demand for copper increased beyond the capacity of the industry. Importation of copper to Australia during the period 1940-1944 was 131,000 tons.When exploration of the Mount Isa orebody was first being carried out in 1928, No. ID diamond drill disclosed the presence of some copper ore lying outside the limits of the Black Star orebody2, but it was not until 1941-1942 that the development of No. 7 level in the Black Star orebody enabled the existence of a lode of copper ore of economic grade to be established. At the request of the Commonwealth Government of the day a programme of development for copper production was undertaken whilst lead smelting was continued as before the war.A series of flotation tests on up to 1,500 tons of ore at a time, was undertaken and the concentrate so obtained was stockpiled. These tests were conducted, using one section of the lead mill, and demonstrated that a concentrate grade of 22-23% Cu with a recovery of 80-85% might be expected.These recovery figures were afterwards much improved, and 93-95%was obtained before the close of smelting in 1946.

Jan 1, 1953

Neutralisation, normally using lime, is the most widely used method for treating high flows of acid mine drainage (AMD). Lime costs can be very high however. If carbonate sources could be used to achieve pH values above six, costs could be greatly reduced. For example, use of locally quarried limestone at Mt Lyell could potentially reduce alkali costs from about $A 3.5 to $A 1 million/year. Methods for enhancing the effectiveness of limestone and magnesite for neutralising Mt Lyell and Savage River AMD respectively have been examined through a series of investigations. Small-scale testwork found that the maximum pH economically achievable with ground limestone was about five, due to slow dissolution rates and surface armouring. The problems of surface armouring were greatly reduced by the use of crushed limestone or magnesite at high pulp densities (75 per cent solids w/w), enabling pH values >6 to be achieved in a practical time frame. The use of particle sizes in the range 6 mm and finer also reduces costs by avoiding the need for grinding, and reduces the problems of solid-liquid separation and solid recycling that arise if large additions of ground carbonate are used. Pilot scale tests were carried out using tumbling drum reactors with limestone and Mt Lyell AMD and a pulsed-bed static reactor with magnesite and Savage River AMD. pH values averaging 6.2 and 6.4 were achieved with Mt Lyell and Savage River AMD respectively. Approximately 80 per cent of feed acidity was neutralised. A preliminary engineering design and cost estimate has been completed on the pulsed-bed reactor and shows that the concept is technically feasible and, if results are confirmed, economically attractive. Further pilot testing is planned.

Jan 1, 2002

By M Fimeri, R Williamson

Sample sizing in the iron ore industry requires significant manual effort to collect, transport, and sieve the samples as well as record, process and report the data. Efforts have been made to automate this process, which essentially emulate the manual process, except that a person is replaced by a robot. Even in these cells, the sieving and sizing operation consumes a significant proportion of robot time. The proposed doubling of production from AustraliaÆs iron ore mines over the next five years will place increasing pressure on sample sizing and interest is increasing in alternative automated methods. One such method is the adaptation of computer vision technology which has been successfully introduced into the mining industry in a range of applications including feed size distribution to SAG mills and oversize detection from screening stations. The limitation of this technology is that only the top surface is visible and this is used as an indicator of total size distribution. Obviously in a sample plant, where 100 per cent of the sample must be measured for acceptable quality assurance, this approach is unacceptable. In order to capture 100 per cent of the sample using computer vision technology a monolayer must be formed either by spreading the sample across a moving surface, such as a conveyor or vibrating platform, and passing this under a camera. This will become a æsurgingÆ load which presents specific problems for some types of computer vision systems, namely those relying on a 2D approach. In this paper a 3D computer vision technology will be described which overcomes the problems associated with measuring particle size in a monolayer and experimental results will be presented which demonstrate its effectiveness for lump and fine iron ore sample size measurement.

Jan 1, 2008

By B J. Wight, R Mackay, S Kim

Improving the understanding of the processes governing ground movements in and around brown coal open cuts is of significant interest for both operating stability and rehabilitation. Brown coal, lignite, is a low-rank coal that is best described as a soft rock, with geotechnical characteristics that derive from its organic origin. It is well-known that low-rank coals exhibit creep behaviour; however, little has been reported on the impacts of chemical processes on brown coal creep behaviour even though organic substances are susceptible to chemical alterations and mining processes will contribute to changes to the geochemical environment; around most mines, groundwater flow patterns are altered leading to enhanced surface water infiltration. Here we study the deformation behaviour of brown coal in response to ion exchange reaction. Our experimental results show that for different ion exchange conditions different characteristics of secondary compression are observed. With the addition of Ca2+, the ratio between coefficients of secondary and primary compression (Ca /Cc) initially decreased, presenting a minimum value at the concentration of 0.005?M, then increased significantly. This implies the importance of ion exchange process for the long-term deformation of brown coal. On the other hand, increasing Na+ concentration did not affect Ca /Cc values significantly over all tested concentrations. The suppression of diffuse double layer was still observed for Na+-treated samples as increasing Na+ concentration decreases Ca values. From a practical perspective, this study did not consider the tertiary creep behaviour and eventual creep failure.CITATION:Kim, S, Mackay, R and Wight, B J, 2014. Creep due to chemical alteration of rocks – a case study in brown coal, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 61–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By K Hskansson

In earlier studies along a mining region recipient (the river VormbScken, northern Sweden), the fraction of certain trace metals recovered in the particulate phase has been found to increase with increasing concentrations of particulate iron. This study was conducted to see if the pattern could be reproduced by adding minor amounts of ferrous iron, simulating groundwater inputs. When the iron is oxidised in the near neutral river water, it will form iron oxyhydroxides and precipitate. Trace metals may be either co-precipitated along with the iron, or adsorbed onto the freshly formed precipitates. If this is the case, such a mechanism may be incorporated as a part of a final polishing step in a mine drainage treatment system based on natural attenuation processes. The experiments were performed at 0¦C and 22¦C, on authentic river waters collected during the winter and summer of 2002, respectively. In order to investigate the influence of particles and bacteria initially present, filtered river waters (4 solution were added to the experimental beakers, increasing the iron content of the waters by 0 - 1.5 mg/L. The oxidation and precipitation processes were followed by means of filtration (0.2 ¦m) for up to seven days. In order to be able to compare the experimental results with the actual field situation, on both experimental occasions, surface water samples were collected also from three stations situated along the river. The samples collected were analysed for iron, calcium, and trace metals by AAS and ICP-MS. The iron oxyhydroxides formed in the experiment did not influence the partitioning of As, Cu, and Pb to the same extent as the particulate iron encountered along the river appeared to do. Cd and Zn were recovered mainly in the dissolved (

Jan 1, 2003