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The cost-effectiveness of blasts involving radiating blastholes is cur- rently restricted in the following ways. (a) Significant percentages of potential explosion energy are not being liberated; the collar sections of some charges are being dislocated and/or desensitised by the detonations of adjacent earlier-firing charges. (b) If the minimum charge spacing is too small, detonation of an early- firing charge can initiate an adjacent charge sympathetically, thereby eliminating the benefit of any intended inter-charge delay. (c) The overall distribution of energy is poor. Appreciably better fragmentation would be achieved if current drill- ing patterns were to be replaced by staggered fans/rings having a toe spac- ing : burden ratio of about 4 : 1. This wide-spaced pattern would enable a higher percentage of the potential energy to be released, would reduce the incidence of sympathetic detonation and would provide a superior overall distribution of this liberated energy. If improved fragmentation is not required, the proposed fan/ring design should allow a significant expansion of the blasthole pattern with consequential cost savings in drill- ing, explosives and initiation.

Jan 1, 1988

Violarite, (Ni,Fe) 3+x S4, is a ubiquitous secondary mineral in the supergene alteration zones of massive nickel sulphide deposits in Western Australia. It is formed by the pseudo- morphous replacement of pentlandite, pyrrhotite and/or millerite, and retains the textures typical of these precursors. Although the composition of the first-formed violarite is related to that of its precursor, supergene enrichment results in an increasing nickel:iron ratio toward the top of the supergene profile. In pentlandite-pyrrhotite ore, the replacement of pentlandite by violarite releases some nickel, which is consumed by the partial conversion of the pyrrhotite to iron-rich violarite. In pentlandite-millerite ore, on the other hand, the pentlandite, on conversion to violarite, appears to release excess iron that participates in the partial conversion of millerite to nickel- rich violarite. The characteristic textures exhibited by the secondary violarite and its replacement products in supergene and gossanitic deposits overlying massive nickel sulphide ores generally enable the original mineralogical compositions of the primary ores to be inferred.

Jan 1, 1973

By J Bartlett, P Quigley

Historical research has played a significant role in the rebirth of the Bendigo Goldfield. The historical research undertaken by the company has been directed to specific areas such as verifying the total gold production of the field, the gold production from defined blocks on each of the major anticlines, the extent of workings of each mine which exceeded 200 m depth, the size and style of reefs mined in each shaft and also within specific domains of the field. Application of this data has assisted in the determination of possible dimensions of different reef styles and the location of mineralisation within each reef system. Description of grade variation, percentage of quartz and the amount and species of accessory sulphide minerals, as well as early geotechnical observations accompanying stoping methodologies, provides valuable analogues for reef structure being defined in the current program. Historical information on shafts on the two anticlines the company is exploring has allowed the postulation and recognition of repetition of reef development within the same stratigraphy in the hinge zones of the adjacent folds. The similarities of mineralisation styles across the field within both specific lithological units and structural setting has had important implications in respect to exploration drill targeting and the estimation of grade and tonnes.

Jan 1, 2003

By Stanton RL

Stratiform lead-zinc mineralization in the Soldiers Cap Group and Kuridala Formation of the Mount Isa Inlier is closely associated with iron-rich sedimentary units or "iron formation", and has many similarities to the Broken Hill deposit in New South Wales. Both the Soldiers Cap Group and the Kuridala Formation have been intensively explored for deposits of this type since the early nineteen- seventies. A mineralized belt of at least eight significant prospects has been identified, of which the Pegmont deposit is the largest and best known example. In most cases the mineralized horizons contain banded galena and sphalerite within a gangue of predominantly quartz-garnet- pyroxene-amphibole rock, sometimes containing a variety of other metamorphic silicates, and apatite. Chemically, the mineralized horizons are distinguished by higher than usual levels of one or more of total Fe, MnO, CaO and P205. Interpretation of patterns of mineral- ization within the belt is based on the Pegmont deposit, where a model of base metal sulphide deposition within restricted basins of iron-rich chemical sediment has been developed (Stanton and Vaughan, 1979). Broadly, the model envisages the deposition of higher grade lead-rich mineralization in the basin centre position, lower grade zinc- rich mineralization in a basin intermediate position, and much weaker copper-rich mineralization in a basin edge position. These three positions reflect a laterally continuous arrangement of silicate microfacies within the original iron-rich sediment.

Jan 1, 1984

By Holliday RJ

The Imperial Smelting Furnace (ISF) was developed in Britain during the 1950's as a process which could produce zinc from a blast furnace. Since then it has evolved into an efficient means of producing zinc and lead from lower grade raw materials, both of primary and secondary origin. These changes have been in response to the need to improve the cost competitive position of the ISF in a climate of decreasing metal prices. The improvements at the Cockle Creek smelter of Sulphide Corporation Pty Limited have resulted from work undertaken in four main areas: 1. Changes in plant design and operating practice to give more stable furnace operation. 2. Improvements to the quality of sinter being charged to the furnace. 3. Improved monitoring of process variables and the formulation of control strategies based on the improved data. 4. Increased understanding of the processes occuring within the furnace shaft to allow predictive modelling to be undertaken. Work in these areas is still progressing but the work to date has resulted in a significant improvement in the production rate and efficiency of operation.

Jan 1, 1984

By N LaBranche

The resurgence of Silicosis and Coal Worker’s Pneumoconiosis (CWP) in coalmines has placed the spotlight back on the management of worker exposure to particulate matter across all mining sectors (Coal Workers Pneumoconiosis Select Committee, 2017). There already exists a substantial body of knowledge on particulate matter and its impacts upon human health (National Academies of Sciences, Engineering and Medicine, 2018). The contribution of silica to respiratory disease is well known. However, it is also clear that there are major gaps in our understanding. In part, those gaps relate to the contribution to adverse health effects of mineralogical constituents in the dust (LaBranche et al, 2021a). It is also becoming evident that the size and shape of the particulate matter can affect its potential impact on human health. The University of Queensland has developed a methodology for characterising respirable and inhalable dust samples using scanning electron microscopy. Multiple samples from numerous mining operations have already been analysed using the UQ methodology. The process has been successful in showing the variety of mineralogical components and particle size distributions present in various areas of the mines.

May 5, 2022

By A J. Tucker, L Bottomley

The principle objective of development mining is to create thoroughfares that can be accessed by personnel and machinery for the entire life of an underground mine. The drill and blast process, being the primary method used when creating these thoroughfares, needs to be able to adequately fracture the rock to be removed whilst at the same time minimising any damage that may be sustained to the rock surface that remains. This process of damage prevention is known by a variety of different names including smooth blasting, sculpture blasting, contour blasting and controlled blasting. Whilst the terms are different, the objective is the same and that is to reduce and better distribute the explosive charges to minimise stressing and fracturing of the rock beyond the neat excavation line. The process in this report will be referred to as perimeter control blasting. This paper will discuss the benefits of using perimeter control blasting in a development mining operation and the theories that govern how these blasting techniques work. The methods that are used to implement perimeter control blasting will also be addressed, paying particular attention to how these blasting techniques have evolved, spawning new and improved perimeter control products. Finally some attention will be given to the process of optimising perimeter control blasting in any underground mining operation.

Jan 1, 2005

By B Roach, P M. Ashley, B Hooper

Mineral occurrences of the Hillgrove Au-Sb-W district are hosted in late Palaeozoic polydeformed, hornfelsed metasediments and Permo-Carboniferous granitoids of the NewEngland Orogen. In excess of 204 individual occurrences have been identified to date with the mineralisation developed as strike extensive (>20 km of known veining) and potentially depth extensive steeply dipping fissures. These are contained within an elongate area measuring some 9 km by 6 km in surface dimensions. Recorded gold production of 720 000 ounces along with current resources in the order of 340 000 ounces highlight the significance of this district. Historical antimony production is estimated at in excess of 50 000 metric tonnes. Significant tungsten of over 2000 t in the form of scheelite has also been produced from the field. Mineralisation is developed in veins, vein breccias, sheeted veins, network stockworks and as alteration sulfide haloes to the main structures. The vast majority of fissures are subvertical and vary in widths of up to 20 m in places. Paragenetic studies have previously indicated that the earliest mineralising event was a scheelite-bearing phase of quartz veining. Subsequent phases of arsenopyrite-pyrite-quartz-carbonate veining were accompanied by gold and minor base metal sulfides. Alteration is typically sericite-ankerite-quartz. Overprinting stibnite-quartz veining with gold-electrum, aurostibite and arsenopyrite form an important subsequent phase. Veining can be inferred from historical records to extend for vertical depths of over 1 km.

Jan 1, 2004

This paper refers to the open cut mining practice developed at Western Mining Corporation's Kalgoorlie Gold Operations (K.G.O.). Mining activity was centred attwo areas, namely W.M.C.'s Siberia "Sand King" and"Missouri" open cuts plus W.M.C.'s "Great Boulder" and K.M.A.'s "Horshoe" and "Morrison -Hannan's Star" open cuts in Fimiston.Kalgoorlie Gold Operations was set up initially to look after W.M.C.'s open cut interests in and about the Kalgoorlie area. The first mine commenced was, the Sand King open cut, approx 75 km NW of Kalgoorlie. it was here that the requirement for a highly selective form of mining first became apparent.

Jan 1, 1984

By S Moradi

The thickener overflow of zinc concentrate, obtained from flotation process in the Angouran plant located in Iran, contains a large quantity of slimes which were transferred to the tailing ponds. These slimes have caused problems of storing and environmental aspects in the Angouran area. The objective of this research is to describe the extraction of zinc from these slimes by leaching method using sulfuric acid in pilot plant scale.Chemical analyses showed that these tailing materials contain 35 per cent of zinc. By XRD analysis, smithsonite is identified as the major constituent. Calcite, dolomite, and cerussite are found as carbonate minerals. A minimal amount of Zn occurs as hemimorphite. Quartz, kaolinite, clinochlore and muscovite are other silicate minerals in the slimes.In the optimal conditions, ie acid leach at pH of 1, temperature of 55¦C, reaction time of 120 minutes and solid-liquid ratio of 1:3 and neutralisation with Ca(OH)2 at pH = 4.5, temperature = 70¦C, time = 90 minutes, the total recovery of zinc obtained was 95 per cent.

Jan 1, 2004

The precious metallogenic belt and its geoloqical-tectonic location in eastern China.The precious metallogenic belt of eastern China is located in the western part of the Pacific gold metallogenic belt, and occurs in the upper levels of the continent cut by a deep fault structure tending NNE and NE, and active during the Mesozoic. The precious metallogenic period ranges mainly from Late Jurassic to Early Cretaceous (160 Ma-110 Ma); subordinate mineralisation occurred during the Hercynian period, and was rare in the proterozoic.Seven precious metallogenic belts are recognised from east to west, i.e. from continent to the margin active belts, as follows:1. Au-Ag-Te metallogenic belt of East Shandong Province2. Au-Ag-Pb-Zn metallogenic belt of west Liaoning-Miyun area3. Au-Os-Ir-Cr-Cu Mo metallogenic belt of Chengde Pingquan area4. Au-Ag-Pb-Zn metallogenic belt of Zhang Xuan area5. Au-Ag-Pb-Zn metallogenic belt of Zhejiang province6. Au-Ag-Se metallogenic belt of East Qinling area7. Au-Pd-Cu-Mo metallogenic belt of Wansu area

Jan 1, 1990

By Boyack DJ

DEFINING AN ECONOMIC TARGETExploration usually begins with the corporate goal of finding a minimum tonnage and grade of a selected mineral. Sometimes this is expressed more simply as a minimum quantity of contained metal without any indication of the desired grade or implied profitability. Such a goal is useful in the selection of exploration areas and the planning of initial drilling programs. However, it should be reviewed as soon as significant mineralisation has been identified. To make rational decisions about exploration expenditure, the potential return from a deposit must be estimated from the outset and re-esti-mated frequently.The potential return will depend on:1. The proportion of mineral which can be economically recovered from the deposit by mining (the mining recovery).2. The quantity of valuable constituent that can be recovered after dilution with waste rock during mining and losses due to incomplete metallurgical recovery.3. Expectations of price and markets.4. Capital and operating costs applying to the selected mining and processing methods, and to transportation and marketing. Increasingly, environmental costs and constraints must also be considered.

Jan 1, 1990

By O Omidi, P D. Katsabanis

The effect of delay time on fragmentation has been discussed for a long period but rarely in a satisfactory and unbiased way. Despite the efforts of many researchers, delay selection for fragmentation improvement or optimisation remains a controversial issue. Large-scale tests have been plagued with scarcity and scatter of observations, while small-scale tests have been associated with boundary effects and energy losses. Theoretical work is often used to produce explanations for available measurements or tries to simplify wave propagation and wave interaction to guide observation and practical work. The present work analyses results obtained from a relatively large number of small-scale experiments in blocks made of grout, and re-analyses results of previous experiments, to conclude on the effect of delay on fragmentation. It is shown that the main contribution of the delay is found in the fragmentation of the larger fragments of the blast, while the small fractions show almost no effect. Samples, where copper liners were used to inhibit penetration of detonation products in the rock mass, showed effect of delay only when short times were used and steady but poor fragmentation when long delays were used. Based on small-scale experiments, it appears that the fragmentation is optimised when a hole fires prior to the radial cracks, produced by the previous hole, reach the free face of the blast. Gas penetration may result in the development of few more fractures that affect the fragmentation of the largest particles of the blast.CITATION:Katsabanis, P D and Omidi, O, 2015. The effect of delay time on fragmentation distribution through small- and medium-scale testing and analysis, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 715–720 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Wilson CJN

The central Taupo Volcanic Zone is a region of intense Quaternary silicic volcanism accompanying rapid crustal extension. Modem central TVZ is the most frequently active and productive silicic volcanic system on Earth, erupting rhyolite at c. 0.28 m' s'. The rhyolites show no major compositional changes with time, but the total extent of magma chamber zonation has changed with the advent of rifting and crustal extension at c.0.7 Ma. At least 34 caldera-forming ignimbrite eruptions have formed a complex sequence of relatively short-lived, nested and/or overlapping volcanic centres in central TVZ. Taupo contrasts with other large silicic magmatic systems in the exceptionally high frequency, but small size, of caldera- forming eruptions. This contrast reflects the thin, rifted nature of the TVZ crust, that precludes the development of long- term magmatic cycles at Taupo.Within central TVZ, non-rhyolitic compositions have been erupted apparently irregularly in time and space; in particular there is no evidence for a geographic separation of basalts from andesites. TVZ is a rifted arc, but its segmented nature, high thermal flux and voluminous rhyolitic volcanism make it unique on Earth.

Jan 1, 1995

By Roxborough F. F

The ability of the Australian minerals industry to successfully manage the changes and challenges that face it in the 21st century depends ultimately on the quality of its human resources. Mining engineers have a vital role in this regard. The education and training that universities are currently giving to mining engineers is under challenge and needs to be reassessed in the light of industry directions for the 21st century. At one extreme is a push for a `finished product' graduate, up and running in `the flavour of the month' issues. At the other extreme are moves to reduce face-to-face university teaching hours and return to the time honoured university concept of `reading' for a degree. The lessons of Mourn make it apparent that neither approach is appropriate to the industry's future needs (Windridge, 1996). Basic knowledge gets rusty with time and new skills need to be learned. In order to conduct mining operations safely, productively and competitively, mining engineers must now accept the need to be prepared for continuing professional development as a career imperative. The concept of being professionally or statutorily qualified for life is no longer valid. This calls into question the purpose, content, structure and mode of delivery of university courses, all of which need to engender the principle and facilitate the cause of continuing professional development. This paper presents a model which aims to deliver a quality assured university education for mining engineers for the 21st century at undergraduate, postgraduate and professional level. The model extends beyond traditional university boundaries to match industry requirements to international best practice. It is based on collaborative alliances and innovative presentation modes which will provide industry access to undergraduate and postgraduate course elements presented by a broad range of national and international academic and industry authorities. It offers the prospect for preserving the best of university ideals in higher education, for developing and maintaining programs of direct relevance to industry needs and for a structured involvement in the continuing professional development of mining engineers.

Jan 1, 1997

By J R. Hernandez-Aguilar, C O. Go, C Acuna

The gas dispersion properties that are the subjects of this communication include three measured parameters, gas superficial velocity (gas rate), gas holdup and bubble size, plus derived parameter, bubble surface area flux. Over the past ten years sensors to measure these parameters have been introduced and those originating from McGill University are briefly described. The sensors have seen extensive use in plant campaigns and experiences on four cell types at three sites are discussed. The impact of frother in controlling bubble size by retarding coalescence is illustrated, introducing the need to understand chemistry/machine interactions in interpreting gas dispersion results. An increase in Sauter mean bubble size (D32) with superficial gas velocity (gas rate, Jg) was found, which followed the empirical relationship where Do ~ 0.5 - 0.6 mm and C and n are fitted parameters dependent on the system (machine and chemistry). Following this trend in Db - Jg, consistent bubble surface area flux (Sb) - Jg trends are also observed. The trend in Sauter mean versus number mean (D10) is used to help interpret the nature of the distribution; as the means approach numerically, the distribution is narrowing. Analysing gas holdup versus gas rate shows both a dependence on location in the cell as well as cell position in a bank, factors which must be accounted for when comparing data from different plants and circuits. The instrumentation and methodologies being developed are presenting new opportunities for incorporating cell hydrodynamics into metallurgical diagnostics. A case study at one plant serves as illustration.

Jan 1, 2005

By P Moser, P Schimek, F Ouchterlony

This paper summarises the findings of 27 model-scale bench blasts in magnetic mortar, which were conducted from 2011 to 2014 at the blasting site of the Montanuniversitaet Leoben.The aim of the study was the investigation of the influence of blasthole delay times in small-scale bench blasts on the face characteristics and cracking damage created in the surrounding rock, which affects the fragmentation in subsequent rows.The test specimens or blocks, which were produced out of magnetite concrete, were roughly 1:100 in scale to normal bench blasts. The confinement of the testing blocks at the sides and back ensured the similarity to normal bench blasts with regard to the wave transmission into the surrounding rock. The specimen contained three or four rows with five blastholes each and were shot row by row, with virgin (undamaged) material in row 1 and increasingly damaged or preconditioned material in the following rows.The tested delay times varied between 0, 28, 73 and 140 µs, which corresponds to 0, 0.4, 1.0 and 2.0 ms/m of burden.The evaluation of the material properties showed that the use of magnetite concrete eliminated the inhomogeneous behaviour of rock, but some unexpected differences of the individual production cycles were still detected.The characteristics of the bench after each blast was evaluated along three horizontal lines out of a 3D model of the bench face. The tested delay time sequences of the virgin (first row) and single preconditioned blasts (second row) produced more overbreak for longer delays, while the third-row shots resulted in a smoothened surface independent of the chosen delay.The introduced damage after every blast was evaluated by an observation of irregularities on the newly blasted bench face. The visible cracks at the top of the testing blocks were documented and divided into several crack families according to their angle, length and origin. The remaining block was broken out of the blasting site after blasting, cut into several horizontal and vertical slices and dye penetrant spray was used to visualise the cracks created. Some of the detected crack families showed an influence of the delay time. The calculated mean crack density and mean crack intersection density showed that longer delays resulted in a higher degree of damage.The fragmentation results were well reproduced by the basic three-parameter Swebrec function. The observed improvement of fragmentation in the second- and third-row blasts was linked to the preconditioning of the burden for the following row while blasting the actual row. With the exception of the simultaneously initiated blastholes, the blasts showed coarser fragmentation for the shortest delays, while the longest delays generated the finest fragmentation.CITATION:Schimek, P, Ouchterlony, F and Moser, P, 2015. Influence of blasthole delay times on fragmentation as well as characteristics of and blast damage behind a remaining bench face through model-scale blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 257–266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By L Lagoeiro

The samples studied in this paper were derived from the iron oxide facies of iron formations (IFs) of the Quadrilßtero Ferrffero, south-eastern Brazil. The rich-iron oxide varieties of the IFs can be regarded as Fe-O systems because they consist predominantly of aggregates of haematite and magnetite crystals. The study was based on carefully selected samples in which magnetite crystals occur as isolated large crystals set in a matrix of haematite grains. Optical microscopy and an electron microscope equipped with an electron backscattered diffraction (EBSD) system were used to investigate the microstructural and crystallographic relationships involved in the phase transformation between magnetite and haematite. The magnetite crystals in the IF samples are partially transformed to haematite and this process is also known as martitisation. This transformation occurs along the crystallographic planes {111} of the magnetite producing a characteristic triangular pattern of interlocking lamellae of transformed haematite crystals that are oriented parallel to octahedral plane {111}. This new generation of haematite is referred to martite because of the martitisation process. EBSD analyses show that the magnetite and the new haematite crystals, martite, share crystallographic planes of highest atomic density, eg {111} and (0001), respectively, possibly due to the ccp and hcp atomic arrangement of the two crystals. Stereographic projections of these two planes therefore coincide when the maxima of their poles are plotted. However, the crystallographic orientation of the haematite crystals in the matrix shows maxima of (0001) poles that do not coincide with those of {111} planes of magnetite. Consequently, it is concluded that the direct transformation to haematite crystals retains the crystallographic orientation memory of the former magnetite crystals, possibly due to the similar manner whereby their atoms are packed together in the crystal structures. On the other hand, no such relationships are observed between magnetite and haematite crystal in matrix. This suggests that haematite grains in the matrix may have been formed by other processes rather than those involved in the iron oxide transformation observed within the magnetite grains.

Jan 1, 2008

By G Power

The successful implementation of sublevel caving (SLC) at Ridgeway Gold Mine (Ridgeway) requires the technical aspects of caving and flow behaviour to be understood. Cave propagation must be controlled and continuous to allow safe extraction of ore below. The understanding and use of processes to manage granular flow behaviour are also required to ensure economic metal resource recovery. Caving and flow technologies are thus critical to the economic viability of the application of the SLC mining technique to Ridgeway Gold Mine. At the time the Ridgeway SLC design was approved there were significant technical uncertainties associated with cave mining methods, including the SLC mining method in competent rock masses. This was in spite of the fact that caving is a relatively low cost mining method. Unique features generating technical risks at Ridgeway include: the fact that the orebody is blind (550 m below surface); highly competent cap rock (RMR >50); and high aspect ratio (height to width ratio of 3:1). Due to the presence of these unique features Ridgeway is considered to be beyond the current state-of-the-art in SLC mining technologies. The success of the technique at Ridgeway to date has indicated that blind SLC mines in strong rock mass can be operated safely and productively, if the technical risks are understood and properly managed. The risk management process was defined by the use of a formalise process to identify and assess the risks to the mine. The major mining related risks were formalised into Major Hazard Management Plans (MHMP) which contained a description of the risk, early triggers indicating the creation of a hazard and a series of agreed responses to be automatically initiated in the event of each trigger occurring. This paper outlines the following with respect to the critical technology areas of caving and flow: international industry, state-of-the-art technology; gaps in the application of this technology; the application of risk management, new processes developed at Ridgeway to bridge these gaps, including issues encountered; and trials and experimentation conducted to develop the new processes.

Jan 1, 2003

By R A. Pax

Operational grinding mills emit significant acoustic emissions which are a consequence of the dynamic environment prevailing inside them. From a technical perspective, the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of primary comminution tumbling mills. To enable a logically coherent picture to be formed of the processes inside a mill, arrays of microphones have been used. This approach allows a clearer picture of the in-mill behaviour of the charge to be accessed. In contrast to single microphone approaches, usually located near the expected charge toe position, an array of microphones allows much more useful information to be obtained from grinding mill noise.This paper will discuss and present data obtained from microphone arrays positioned at the toe and shoulder locations of a mill, and how this information can then be used for the optimisation of grinding mills in real-time.CITATION:Pax, R A, 2012. Determining mill operational efficiencies using non-contact acoustic emissions from microphone arrays, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 119-126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012