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By T J. Laing, A B. Richards, A J. Moore

Blastholes fired in a pattern with a constant initiation delay create a frequency in the ground vibration similar to that from a percussion instrument, such as a drum, in the air. A constant firing delay generates a prime or forcing frequency into the ground motion. The forcing frequency may then be modified by ground transmission characteristics into subharmonics of the forcing frequency. The moving vibration source between blastholes also creates a frequency shift because of a Doppler effect. Other wave interactions may form beats. The effects are exacerbated by the accurate firing times of electronic detonators. This paper demonstrates how observations of wavetraces and frequency spectral analysis were used to recognise:Doppler effect and frequency ellipsoidssubharmonics (and sub-subharmonics) of the forcing frequencybeat formation that may double or triple peak particle velocity (PPV) levels.Recognition of beats permitted techniques to be used to control ground vibration from coal overburden blasting to limits deemed to cause no further instability in a slip failure. An understanding of the science involved has practical application elsewhere that has been successfully applied to initiation timings to reduce PPV and adverse human and structure response from other blasting operations.CITATION:Moore, A J, Richards, A B and Laing, T J, 2015. Blasting harmonics and controlling peak particle velocity, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 527–532 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By G Hancock, J Lowry, W D. Erskine, D Jones, T Coulthard, M J. Saynor, P Lu

An 8 ha trial landform was constructed in late 2009 at the Ranger Uranium Mine, located 250 km east of Darwin in the wet-dry monsoonal tropics of northern Australia. The objective of the trial, which comprises two surface cover types on a uniform two per cent slope, is to provide long-term data to guide the development by Energy Resources of Australia Ltd (ERA) of its landform closure strategy. The scope of the work program for the landform includes many aspects; however, this paper is focusing on run-off and erosion rates. The run-off and erosion rates are used to assess the long-term geomorphic stability by comparing measured with modelled export rates from a landform evolution model.Monitoring of wet season run-off is undertaken collaboratively by the Environmental Research Institute of the Supervising Scientist (ERISS) and ERA, on four purpose-instrumented 30 m by 30 m erosion plots. Continuous measurements are made in rectangular broad crested (RBC) flumes located at the outflow of each plot, of water level, turbidity (a surrogate for fine suspended sediment) and electrical conductivity (EC) (a surrogate for solutes). Each plot has a tipping bucket pluviometer located near the RBC flume. Bed load is collected monthly.This paper reports the findings of rainfall and bed load from the first two wet seasons (2009 - 2010 and 2010 - 2011) following construction. The field measured loads will be compared with the predictions made by the Cellular Automaton Evolutionary Slope and River (CAESAR) landform evolution model. Initial results indicate that predicted rates of sediment export from the CAESAR model are similar to measured export rates. This provides confidence in the capability of the model to predict stability of the future rehabilitated mine area, especially during the critical initial years following construction. CITATION:Saynor, M J, Lowry, J, Erskine, W D, Coulthard, T, Hancock, G, Jones, D and Lu, P, 2012. Assessing erosion and run-off performance of a trial rehabilitated mining landform, in Proceedings Life-of-Mine 2012 , pp 123-132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By S Hapugoda, J R. Manuel, M P. Ma, L Lu

Iron ore sinter quality depends heavily on the mineralogy, textures and physical structure of the sinter, which is formed upon solidification of the primary sinter melt. The interactions of the initial sinter melt with its surrounding materials will impact on the properties of the primary sinter melt and consequently the solidified structure of the sinter. By using a high-temperature visualisation system, in situ studies have been conducted on the effects of melt compositions (Al2O3, SiO2 and MgO) on the interfacial phenomena of the sinter melt on a natural iron ore substrate. It was found that the melt composition significantly influenced the wettability between the sinter melt and the iron ore substrate. The interactions between the sinter melt and the natural iron ore substrate were also examined. Such interactions can lead to further changes of sinter melt composition and hence the sinter melt properties that, in turn, further affect the wetting behaviour of the sinter melt.CITATION:Ma, M P, Lu, L, Hapugoda, S and Manuel, J R, 2013. Effects of melt composition on the interactions of sinter melt on a natural iron ore substrate, in Proceedings Iron Ore 2013 , pp 431-440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Sano S, Ishikawa T, Nagaoka H, Hayashi Y, Hasegawa M

The stirred mill is regarded as one of the most efficient devices for micronising materials and has come to be actively used for preparation of fine particles. Recently, the demand for ultrafine particles was increased in many kinds of industries. In this paper, autogenous grinding to get submicron particles based on mutual friction feed material has been carried out using a stirred mill. The mill used was made of stainless steel and its volume was about 5.5 litres, and has 12 impeller blades. Sample used was limestone. In the present work, two operating parameters such as stirring speed and feed size of limestone were considered. The ground products were sieved in the size range from feed size to 325 mesh (45 lun), and from 45 to 0.17 pm the size distributions were measured by a laser diffraction and scattering method. The progress of grinding was evaluated by the increasing amount of submicron particles in products. As a result, the rotational speed of impeller with the minimum energy consumption to produce submicron particles was observed. It was found that the autogenous grinding with a stirred mill is an effective method for producing submicronized limestone.

Jan 1, 1993

By M Khanal, J Qin, B Shen, Y Duan, X Luo

Gaining confidence in interpreting rock and strata properties of the coalmine roof is necessary for design, maintenance, modelling and optimisation of roadways supports. One of the key causes of roadway instabilities experienced in underground coalmines is an extreme variable nature (thickness, competence, discontinuities etc) of the coalmine roof. Normally, the thickness and strength of the roof are characterised with the geotechnical and geological data gathered from exploration boreholes, which are drilled often at considerable distances apart. This limited data cannot capture localised geological variations in the coalmine roof. With this background, this paper explores feasibility of using measurement while drilling concept to perform geotechnical characterisation of the coalmine roof. The parameters, for example, penetration rate, rotary speed, torque, sound, vibration, obtained during the drilling process can provide valuable insights into geotechnical properties. The paper describes the progress of the experimental work conducted at the laboratory on synthesized concrete samples representing various rock strata using a field-scale drilling machine. The samples with and without interfaces have been tested to replicate various underground roof strata. The signals returned from the drill machine, as the drill bit passes through the layers, have been analysed and interpreted to characterise whether the drill response data can differentiate various strengths associated with the rock layers. The initial laboratory results are promising as they show distinct responses of the various sample blocks in a controlled environment. The drilling data can differentiate the synthesized rock samples and detect ‘signatures’ of the roof strength variability and delineation of lithological interfaces (transitions). The weight and torque on the bit vary and show dependency on the strength of the blocks.

Nov 29, 2022

By Leaning R. W, Goodman P. J, Lidgate P. N

The impact of computer based design tools on the engineering industry has been enormous. With the advent of computer aided design and its continual evolution into tools such as 3D design and photogrammetry the face of the engineering office ha

Jan 1, 1998

By J Chen

Research conducted into backfill drainage at Mount Isa Mines since 1992 is described. Piping in draining backfilled stopes has been the primary cause of bulkhead failures and emphasis is placed on research into the piping mechanism. Laboratory and in situ tests aimed at understanding the piping mechanism have been conducted and the results are presented. A case history of piping in a draining bench stope fill mass is described and a technique for reducing the potential for bulkhead failures in bench stopes is presented. Hydraulic fill is produced by standard cycloning of tailings and the overflow (reject material) is sent to thickeners prior to placement in the tailings dams. Research into the partial introduction of thickener underflow into the backfill system and its influence on backfill drainage is also described.

Jan 1, 1998

By L Huang

"Successful rehabilitation of tailings landforms of tens to thousands of hectares in size at base metal mines is critical to mining companies’ ‘social licence to operate’. Rehabilitation technology used is closely related to both the economic sustainability of the mining company and the ecological sustainability of the mined environment. Conventional technology to rehabilitate mine waste landforms is costly and constrained by the availability of soil (to reconstruct root zones) and clay materials (to reconstruct compressed layer). Depending on mine waste properties and site-specific resource availability, it is not uncommon to cost A$0.1–0.5 M/ha for the establishment of conventional cover systems over mine waste domains, which often accounts for large proportion of the total closure costs. This can lead to costs approaching several hundred millions dollars for rehabilitating larger tailings and acidic waste rock using conventional cover systems.The present extended abstract proposes a suite of new technologies to tackle the problems outlined above and discusses critical factors in successful rehabilitation from substrate levels to the whole landform performance, in two key aspects:in situ engineering of tailings soil to offset/reduce materials requiredin situ chemical engineering of massive hardpan layer through alkali-activation and mineral gel cross-linking network mechanisms to encapsulate reactive tailings and achieving sustainable hydro-geochemical stability in root zones.This aims at functionally replacing the roles of the compressed clay layer and capillary breaks in conventional covers. These technologies would improve both the economic and ecological sustainability of mine waste rehabilitation, thus addressing the triple-bottom line of mining and mineral processing industries not only in Australia but other countries.CITATION:Huang, L, 2016. Emerging technology for economic and ecological sustainability in the rehabilitation of metal mine tailings, in Proceedings Life-of-Mine 2016 Conference, pp 128–131 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 28, 2016

The current economic climate and demand for iron ore has resulted in mine operators being prepared to accept aggressive slope designs and associated failures provided that they can be quantified (ie volume of failure and clean up costs, etc) and incorporated into the mining costs, at a feasibility study level. This has numerous implications for pit slope design/geomechanics. Typically when geotechnical engineers conduct slope stability modelling a single value, usually the average or mean value for model input parameters (ie structural orientations, material properties and hydrological conditions) are chosen. The implications resulting from using a single value for model input parameters will vary depending on how the modeller has chosen the value, ie should the modeller choose a mean value from a log-normal distribution of material strengths an optimistic representation of the stability may eventuate, consequently if the designer decides to conservatively downgrade the values by a nominal factor, a pessimistic representation of slope angles may occur, which would result in excessive stripping and mine development costs. A more realistic and representative way to model the inherent variability of geological/geotechnical conditions would be to do so probabilistically. Whereby the modeller can assess the variability of the geological structure as observed/recorded during the core logging process and a similar approach for the material strength properties. The final model output would be a distribution of factors of safety in relation to overall slope angles, ie probabilities of failure for individual slope angles could be determined. This output (graph) could be modified by the mining engineer to incorporate mining costs as well as clean up costs for the respective slope angles and associated failure volumes, ie probabilities of failure. The author intends to provide a detailed overview of the processes involved in deriving a geotechnical design, ie; starting from the data collection phase (core logging/face mapping), through to the data interpretation and formulation of slope parameters; determining the variability and uncertainties associated with each of the process; ensuring that it is adequately captured in the model input parameters; and how the mining engineer could utilise this information to derive final feasibility study mining costs.

Jan 1, 2009

By S Ravn

Under platform exhaust (UPE) systems are often designed into metro stations as a means of removing heat generated by trains as they come to a halt in the platform. These systems are designed to extract heat from the brakes and brake resistors directly at the source in order to capture as much heat as possible before it can enter the public areas of the station, or contribute to the temperature build-up in the tunnels. Due to space requirements for the associated duct and air handling units, the UPE plays a significant role in the geometric design of the platform and station as a whole.In recent years questions have arisen as to the effectiveness of UPE systems. However, very little data is available for designers to use when making important decisions on the station designs for new metro systems. This is important as significant savings could be achieved by omitting or re-designing these systems for new build stations; not only due to the capital costs of space provision for the duct itself but also due to the associated operation and maintenance cost of the UPE system.This paper will present recent measurements of the UPE system of the Copenhagen metro together with one-dimensional (1D) simulations, looking at typical dispersion of heat into the station plenum box and air exchange through draught relief shafts as the train enters the station in order to evaluate the effectiveness of the UPE system. The aim of this paper is to disseminate the results of measurements and analysis to increase awareness of the issue and to provide discussion relevant to designers in their evaluation of heat removal systems in new build station designs.

Mar 8, 2011

By G Collecutt, T O’Beirne, D Humphreys, J Greenwood

Much of our knowledge of the behaviour of underground coal dust explosions has been derived from less than full-scale experimental explosions in facilities as small as 0.25 m diameter pipes. Although a substantial body of research has been undertaken in larger galleries approaching the size of full-scale modern mine roadways, there are still questions regarding the scaling of results to full-sized roadways in modern coalmines. Questions also surround the issue of comparing or scaling results between smooth and rough walled galleries, round and rectangular galleries and galleries with differing wall thermal properties due to different materials of construction.This paper will examine the influence of gallery size, cross-section area and wall roughness and thermal properties upon the characteristics of a coal dust explosion. Data from past explosion research will be examined and assessed for its application to the problem along with theoretical considerations for these factors.Recommendations on the design and minimum appropriate size of explosion galleries for assessing the performance of explosion inerting strategies, passive and active explosion barrier performance and determination of appropriate pressure ratings for ventilation structures will be made.CITATION:Humphreys, D, Collecutt, G, Greenwood, J and O’Beirne, T, 2015. The impact of facility construction and scale on the characteristics of experimental coal dust explosions, in Proceedings The Australian Mine Ventilation Conference, pp 301–308 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By French D

In presenting this paper may I preface my remarks by recognizing the presence here to-day of the many delegates from the overseas mining communities throughout the world. That is to say - those delegates not representative of Companies resident in Australia. This does not mean that my comments following are directed solely to the Australian exporter - far from it. The Company which I represent is internationally based. The experiences we have had in dealing and negotiating with our good friends the mineral cargo shippers vary very little in any operational area. However for the purposes of this exercise this address is based on some of our experiences within the Australian trade scene with the emphasis on the fact that we believe it has application to all trading areas.

Jan 1, 1989

By D Bruggemann, F Sereshki

There has been an ongoing research on coal and gas outburst for the past two decades at the School of Civil, Mining and Environmental Engineering, University of Wollongong. Research study began with a humble beginning, initially conducting basic laboratory studies on the coal and gas properties, progressing into the determination of gas content of coal by sorption technique and the effect of gas pressures on coal strength. The present laboratory facilities and research interests are extended to include the study of coal permeability and shrinkage properties and their effect of gas drainage characteristics with respect to gas type, and pressures. All the changes are examined with respect to changing in-site geological conditions of the coal deposit investigated. The aim is to provide a long-term support to industry in establishing a data bank for Australian coal deposit characteristics and properties.

Jan 1, 2005

Effective pre-splitting is a key feature of wall control blasting. Most mining operations use historical designs or rules-of-thumb for designing pre-split blasts. If productivity and safety benefits are to be gained, these methods need to be improved in order to accurately predict pre-split performance. This will become more pertinent as overburden depths increase, placing more demands on the pre-split operation. A classical qualitative quasi-static description of pre-splitting (Kutter and Fairhurst, 1968) is presented and it is shown to give some useful insights into the pre-splitting process. In particular, it is clear that the time interval between the initiation of adjacent pre-split holes is a very important factor. In terms of this analysis, it is shown that current techniques which employ detonating cord as the surface initiation system are not optimal. A static quantitative model for pre-split design which has been widely reported is then discussed and its simplifying assumptions and their implications are examined. It is shown that several of the assumptions may be reasonably justified in the light of real pre-split results. It is concluded that the model should yield conservative designs. For this model, the key calculation of the blasthole pressure that is needed to determine the required explosive charge is highlighted. Popular methods employed in the literature for describing the expansion of real detonation products are shown to be inappropriate and an alternative method using the non-ideal detonation code, CPeX, is proposed.

Jan 1, 1995

By J Zhao, Q B. Zhang

The shock behaviour of a material represents its response to very high strain rate loading at pressures associated with those generated by explosive and blasting loadings. Three sets of shock wave experiments have been conducted to determine shock Hugoniot behaviour, spall tensile strength and shear strength using a plate impact facility. Embedded manganin stress gauges (ie longitudinal and lateral gauges) and high-speed velocimetry using heterodyne techniques were used for the measurements of stresses, shock velocity and free surface velocity. The gabbro exhibited classic linear Hugoniot equations of state in the US-up (ie shock velocity-particle velocity) plane; while for marble a polymer-like non-linear response was observed. The detailed experimental procedures used to make these measurements are to a great extent standard methods when determining mechanical properties and deformation fields at high strain rate.CITATION:Zhang, Q B and Zhao, J, 2015. The response of rock materials to one-dimensional shock loading, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 665–672 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The recent paper by Bain (1981) contains an unfortunate, and potentially misleading typographic error. On page 9, second paragraph, Bain states that, "some samples of drill core from the (Candlow) Formation ... contain up to 90 ppm gold and 2 000 ppm arsenic". The gold value should read 90 ppb. In fact, in the original version of the paper (Bain, 1980), the gold value quoted was actually 60 ppb.Bain also refers briefly to some geochemical data which is attributed to me, and which I feel require some clarification.In addition, the paper contains some factual errors relating to the occurrence of carbonate and potential host rocks to Carlin-type gold deposits in the Candlow Formation.

Jan 1, 1981

By M Hilden, K Barbosa, M Yahyaei, C Ndimande, K Runge, V Jokovic

Classification devices provide a link between comminution and flotation. Basically, it determines which particles are diverted back for additional grinding and which ones pass to downstream flotation. Therefore, the classifiers play an important role in the performance of a mineral processing circuit. Hydrocyclones are the most common classifiers used in wet grinding, despite being associated with poor classification efficiency. Hydrocyclones are widely used due to advantages related to low maintenance as well as reduced capital and operating cost. Other classifiers, such as fine screens, have much better classification efficiency compared to hydrocyclones. The major challenge of using screens in an operation, however, is their large footprint and increased maintenance requirements relative to hydrocyclones. Some researchers have demonstrated that switching from hydrocyclones to screens, as the classifier device in a ball milling circuit, resulted in a 20 per cent increase in plant throughput and significant improvements in coarse particle recovery, resulting in a 6 per cent increase in overall flotation recovery. However, it is known that these benefits of improved classification are very much ore specific, ie depending on the ore response. Therefore, there is a need to estimate the benefits of improved classification in pilot scale testing before the plant could consider the potential classifier upgrade. This paper presents the results of two pilot-scale grinding tests where the ore sample was processed using different classifiers: a traditional hydrocyclone and hybrid classification involving the use of a semi-inverted hydrocyclone followed by a screen. The size specific energy and circulating load were used to compare the performance of the grinding circuit. The grinding product was subject to mineral liberation analysis and the impact of classification efficiency on the mineral liberation is discussed in the paper.

Aug 24, 2022

By M Rimes

This paper describes a technique to predict achievable head grades and likely variances from target grade for the Shovelanna Iron Ore Project, in the Pilbara region of Western Australia. The block model from which the production schedule is produced was created from a wide spaced drilling program and was classified as an Inferred Resource under the JORC Code. Ideally, production schedules and target grades would be determined using a combination of Proved and Probable reserves. However sometimes it is necessary to consider the requirements of potential off-take parties who have specific grade tolerances. A technique is needed to simulate mining sequences and grade variations early in the planning process, using an æexplorationÆ block model rather than the normal æminingÆ block model. Marketing contracts require examination whether the target grade {Fe, P, SiO2, Al2O3 can be kept constant, or must be revised during the life of the mine. A model (written in ExcelÖ using Visual Basic macros) develops a feasible, close to optimal, mine plan from block model data. Cut-off grades for minable ore are chosen. The model evaluates ore tonnage, grade and stripping ratio against depth. Outputs at this stage include plots of slices through the orebody, at nominated x, y and z coordinates, showing ore grade, waste, drill hole locations and topography. The model then searches for a feasible satisfactory mine plan. The initial grade target is the average for the identified ore blocks. The available block list (ABL) at any time is the set of ore blocks, any one of which can be mined without removing any other ore block. The entire initial ABL has an unacceptably large ætotal grade stressÆ, defined as [(Grade-Target)/Tolerance]2, summed over the four relevant minerals {Fe, P, SiO2, Al2O3}. The model trims the ABL, removing the block most harming the total stress. Trimming is repeated until the total grade stress reduces to an acceptable level. The trimmed ABL defines the first mine campaign. Removing the trimmed block set, a second ABL is exposed, which is again trimmed and mined. The process is automatic: a few seconds computation provides a complete mine plan. Re-running the model with adjusted grade limits quickly shows whether a uniform target can be achieved or whether the target must be modified during the mine life.

Jan 1, 2007

In contrast with mining in areas close to the main centres, mining in remote areas is characterised by comparatively high initial investment and relatively high running cost for the life of the mine. This is because of:the real cost of establishing and running the operation at a location distant from the necessary infrastructure; and the perceived risks priced into their costs by the multitude of suppliers involved in the project. Optimal co-operation between the mine and the supplier in developing the right rela tionship and the correct technical solution permit both cost elements to be reduced. This re duction may well mean the difference between success and failure. This paper examines the possibilities for optimising the contribution of the equipment supplier to the overall success of the process. Issues covered include the necessity to provide more than merely equipment fit for the purpose , but also the need to maximise the benefits of equipment ownership over the life of the mine. A simple method of determining the optimum timing for equipment replacement or rebuilding is proposed . Furthermore the maintenance contract (or performance agreement) is suggested as a means of leveraging the supplierÆs commitment to the mining operation. The specific examples are based on experience with mobile equipment but the methodology has relevance to other equipment and supplies.

Jan 1, 1998

By M T Roche

The Cannington deposit is one of the largest accumulations of silver-lead known. Located 135 km southeast of Cloncurry in North West Queensland (Figure 1), Australia, the deposit is currently in the feasibility stage of its development. The deposit is named after the nearby Cannington Pastoral Property which runs some 25 000 sheep on 'downs' country. The investigations of the Cannington deposit are carried out under the authority of Mineral Development Licences 139 and 144 and Exploration Permit for Minerals 6788, Answer Downs. Exploration for Broken Hill Type (BHT) silver-lead-zinc deposits in the Mt Isa region has been undertaken by The Broken Hill Proprietary Company Limited's Minerals Division (BHPM) since the early 1980s following in-house research which showed that the Eastern Succession of the Mt Isa Block exhibits characteristics which were favourable for hosting BHT

Jan 1, 1994