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It is difficult with inadvertent explosions to establish fundamental data, especially of original dust, of pressure, temperature etc. and of ventilation oscillations, as exposed personnel rarely survive. Retrospective data from explosions must be derived from damage, from fatalities, from ventilation analyses, from analyses of dusts and other indications of temp- erature and duration of temperature. The five disastrous explosions selected for analysis provide examples of what data can be established as to the cause and extent of explosions. Such information is required for legal etc., inquiries subsequent to explosions, but most importantly to give the best guidance for avoidance of possibility of further Disasters.

Jan 1, 1981

By M Sciortino, J Korczak, J Muinonen, A St-Jean

The Dumont deposit is a large (1179 Mt reserve), low-grade (0.27 per cent nickel) nickel sulfide project located in the Abitibi region 25 km west of Amos, Quebec. Royal Nickel Corporation (RNC) acquired the project in 2007 and has since taken the deposit through to feasibility. The disseminated nickel sulfide and alloy mineralisation is hosted within the serpentinised dunite subzone of the Dumont Sill; a differentiated, pervasively serpentinised, ultramafic sill of komatiitic affinity. Pentlandite ((Ni,Fe)9S8), heazlewoodite (Ni3S2) and awaruite (Ni2.5Fe) are the dominant nickel-bearing metallic phases and can be recovered by conventional methods (flotation, magnetic separation). Non-recoverable nickel is also present within serpentine and olivine of the silicate matrix.A detailed mineralogical program including 1420 QEMSCAN« samples and 4400 electron microprobe points was undertaken to increase the understanding of the nickel deportment in the various recoverable and non-recoverable phases in a spatial context across the deposit. A total of 105 metallurgical tests have been performed under a standard procedure which have linked the mineralogy to metallurgical performance. This has allowed the creation and modelling of geometallurgical domains on a block-by-block basis to understand the recovery variation and metallurgical performance throughout the deposit. Understanding the spatial variability of Ni deportment in recoverable and non-recoverable phases through mineralogy is the key to understanding metallurgical performance, thus unlocking the value of the Dumont deposit and other large tonnage low-grade ultramafic nickel deposits.CITATION:Sciortino, M, Muinonen, J, Korczak, J and St-Jean, A, 2013. Geometallurgical modelling of the Dumont Deposit, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 93-100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By K P. Crameri

The Beta Hunt orebody is situated on the south western limb of the Kambalda dome. It is one of the nickel occurrences in the area which fall into the category of æKambalda Style OrebodiesÆ. These orebodies are renowned as being continuous uniformly mineralised ribbons of nickel sulfide mineralisation. Interestingly, Beta Hunt does not conform to this notion of continuity and uniformity and is in fact highly irregular in its ore distribution due largely to the influence of post depositional structure. In an attempt to understand the ore distribution at delineation stage rather than development stage a detailed footwall topography model is created using all available drilling data. To augment this drilling data, the routine use of downhole EM and borehole radar has been introduced to provide data beyond the confines of the drill core to enhance the geological interpretation of the footwall topography and the distribution of the mineralisation. The implementation of a detailed footwall model and the use of downhole geophysics has proved to be very effective in resolving the orebody complexity issues. Ongoing development of the methods used will continue to refine the interpretation of the geology to enable more efficient extraction of the orebody.

Jan 1, 2006

By P Holtham, R Dunne, D Stoll

Flash flotation is a process designed to remove coarse, liberated, fast floating minerals from hydrocyclone underflow. Irrespective of liberation, coarse particles would normally remain in a grinding circuit until they are reground fine enough to report to the hydrocyclone overflow. Additionally, minerals of high density also report to hydrocyclone underflow despite being fine in size and/or liberated because hydrocyclones separate on the characteristics of both particle size and density. Dense particles continually reporting to the hydrocyclone underflow can lead to over-grinding and the production of ultra fine particles. These particles exhibit slow flotation kinetics and thus are difficult to float in conventional flotation circuits. Therefore, removing coarse, liberated particles from the hydrocylcone underflow by flash flotation has the potential to improve recovery and can improve dewatering unit operations and reduce grinding costs.The impact on the overall performance of the flotation circuit by removing coarse, fast floating minerals prior to conventional flotation is not well understood. Ultimately, predicting the overall recovery improvement provides the justification for the installation of a flash flotation cell within the milling circuit. This paper will describe attempts to estimate flash flotation recovery improvements to the overall circuit using kinetic data from simplified batch cell flotation tests combined with limn-based modelling techniques.CITATION:Stoll, D, Dunne, R and Holtham, P, 2012. Modelling the impact of flash flotation from batch cell flotation tests using limn, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 179-184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By B Lance, D O’Brien

The Hidden Secret ore body is located within the Mt Charlotte underground mining system in Kalgoorlie, Western Australia. Mineralisation of the Hidden Secret ore body is lode style and therefore differs from the typical economical mineralisation mined at Mt Charlotte and consequently demanded a novel approach to the mining methodology. The ore body is lens like in shape, extending 200m along strike, 210m vertically, and dipping at 55 degrees. The lode width varies from 1.5m at the extremities to over 22m in the central zone of the ore body. Average grade is 3.4 Au grams per tonne. The initial mining methodology was Modified Avoca utilising Longhole Open Stoping with pillars, in a bottom up stoping sequence. However, as Hidden Secret became better defined and wider than initially modelled, it was identified that a high portion of gold would remain in the pillars and other mining concerns emerged such as remote backfilling large open voids and potentially unsafe vertical standoff distances between levels and wide open stopes. A re-evaluation of this method was undertaken and a new approach adapting a variation of Avoca methodology was identified to remove the rib pillars and replace them with a sill pillar separating the 4 levels into 2 distinct blocks. This new approach provided an immediate advantage by removing the bogger backfilling activity from the same level of the active stope front, enabling stope drilling and prepping to occur during the backfilling cycle. Bogging productivity has also improved as the fired ore is funnelled to the draw point by the backfill rill, significantly reducing the requirement for remote bogging thus improving bogging productivity. This mining method is currently in progress in the first of the two mining blocks and is on track to realise the targeted recovery of 7,700 ounces from the rib pillars.

Mar 15, 2021

By G Cao, Y R. Cui, J X. Zhao, H P. Gui, G H. Wang, Z M. Wang, M M. Ren, B Li

Pyro-metallurgy is still the main process for lead production and a lot of lead direct smelting processes have been developed in recent years. All the processes will experience two steps in common. The first is the oxidisation of PbS to PbO and then reduction from PbO to Pb, furthermore, from ZnO to Zn. So, the composition of melts, especially the slag composition at reduction step change continuously. Up to now, there are few systematic results on the slag physical-chemical properties with its composition change. In this work, the typical lead direct smelting processes were analysed from theoretical and practical standpoints. The full-period slag composition and slag melting point change were compared. Especially, to the PbO and ZnO reduction steps, based on the full-period slag composition change, the slag properties were predicted. Based on dust composition and test results, the mechanism of Pb compound evaporation and its effect on practice and measurement of high PbO bearing slag physical-chemical property is discussed. It is suggested that to restrain the evaporation in practice and to obtain more accurate measurement results of physicochemical properties of smelting slag are the key problem not only to set high efficiency, energy saving process, but also to environmental pollution control.

Aug 21, 2024

By H Yuan, H Tian, Y Zhang, Z Wang, C Wang

Submerged arc welding (SAW) is one of the significant metal-joining processes for manufacturing marine vessels, steel pipes, and offshore structures with high deposition rate and engineering reliability. Welding flux serves several essential functions, including atmospheric shielding, arc stabilisation, bead morphology control and weld metal (WM) refinement. Therefore, from a thermodynamic point of view, the focus for flux design and WM compositional/microstructural modification has been placed to elucidating the transfer pathways and mechanisms of major alloying elements, such as Si, Mn, Ti and O during welding. To this end, a thermodynamic model has been established to predict alloying element contents in the WM. Such functions are enabled by the physicochemical properties of the fluxes, which are inherently rooted in the nature of the fluxes. A unique yet systematical investigation, including physicochemical property changes and structural evolution behaviours, has been conducted over the wide range of fluxes applied to actual welding of EH36 shipbuilding steels. Combined with spectroscopic methods, structural behaviours of network formers such as SiO2, Al2O3 and TiO2 and network modifiers such as MgO, MnO and CaO have been illustrated. Viscosity and ionic conductivity have been found to be positively associated with the degree of polymerisation.

Aug 21, 2024

By A Sainoki, D Fukuda, K Shioya, C Zhang, M Sharifzadeh, T Yamaguchi, S Saydam, J Kodama, C A. Amagu, Y Fuji

In an open pit mining, ensuring stability of rock slope has been one of the major challenges. As the instability of rock slopes can results in slope failures; consequently, endanger the lives of workers, affect mining operations, and often lead to economic losses. Therefore, it is practical important to study the stability of rock slopes to ensure safe, smooth, and effective mining. The stability of rock slope of about 130 m height at Higashi-shikagoe limestone quarry, which has experienced slope failures four times since 1996, was assessed. The rock mass at the quarry is consists of mainly limestone, schalstein and slate rocks intersected by clay seams of about 70 m thick at footwall of the rock slope. Previously, the effects of limestone excavation at the foot of the rock slope and shear failure due to rainfall infiltration have been investigated. Although clay is widely known to plays a vital role in the stability of slopes in engineering projects including mines, but its impacts on slope deformation at the study quarry are not adequately examined. Therefore, the present study addressed the impact of presence of clay on slope deformation at Higashi-shikagoe limestone quarry by employing both field displacement measurements and numerical simulation. Firstly, surface displacements measured by automated polar system (APS) for over eight years were analysed to understand the overall characteristics of the slope deformation. The measured results show that the displacement gradually decreases with time. The maximum displacement of about 100 mm was observed at middle of the rock slope. Secondly, the effect of deterioration and plastic behaviour of the thick clay layer were simulated using two-dimensional finite element method (2D FEM). The simulated results reveal that the clay exhibited deterioration by water contact and plastic behaviour arising from mining activities at the footwall of the clay zone. Based on the characteristics of the measured and simulated results, it was found that the displacement induced by the effect of deterioration of clay is more noticeable at the north side of the quarry whereas displacement induced by excavation is quite significant at the south side of the quarry if clay behaves as an elasto-plastic material.

Nov 29, 2022

The building is a lofty, well-ventilated one of hardwood frame, with galvanized-iron walls and roof, and consists of five spans running north and south, covering a total length of 236 ft. Each span is composed of nine bays of 1:3-ft. centres, making the total width of the building 117 ft. The refinery is situated conveniently at a distance of 100 yds from the smelters. Through the third span of the building runs a 5-ton electric overhead travelling crane, of a 3-motor type, with a span of 29 ft. The crane runway extends over a railway line, which connects the smelters to the refinery. This crane is llsed for handling bullion, coal, melting kettles, lead pumps, &c. A 3-ton crane of similar type, but with a 50-ft. span, runs through the fifth span of the building and also extends over the railwav line alreadv mentioned. This crane is used to load the soft lead into railway trucks, or to stack lead awaiting shipment in the area covered by the crane's operations.

Jan 1, 1918

By L Mariano

Three selected iron ore samples from the major bedded and channel iron deposits of Western Australia were analysed using a scratch test commonly used in the oil and gas industry. The portable commercial equipment dubbed Wombat cuts a groove on the surface of the sample with a cutter under imposed depth of cut and cutting velocity. The normal and tangential components of the force acting on the cutter are recorded with a high degree of precision (about 1N) at fine spatial resolution of about 20 measurements per millimeter.The intrinsic specific energy inferred from the scratch test measurements is found very well correlated with a classical measure of strength such as the uniaxial compressive strength, for over 300 sedimentary rock samples.The results obtained on the iron ore samples are comparable to those obtained on oil and gas sedimentary rocks. This method could provide an objective and semi-automated measurement of material strength and brittleness in iron ores that can possibly be correlated to the lump to fines ratio.

Jul 11, 2011

By R J. Longbottom

In this study the bonding within reduced titanomagnetite-coal compacts was investigated. The aim of the study was to better understand the binding mechanisms in the reduced compacts and, based on this understanding, to improve on their strength.Titanomagnetite ore was combined with sub-bituminous coal to form compacts. The compacts were then reduced by heating in a thermogravimetric furnace (TGA) to temperatures between 1000 - 1300°C under argon. The reaction progress was monitored by measuring the weight loss with time. The reduced compacts were found to have low strength in compression testing. The main form of bonding between the reduced titanomagnetite particles in the compact was by the formation of a slag-like material. Increasing the fi nal reduction temperature was found to have a profound effect on the strength of the compacts by promoting the formation of this slag-like material.Attempts to improve the strength of the compacts were made by changing two variables, the type of coal and the addition of rice husks. The addition of coking coal gave reacted samples that had little strength, while the addition of rice husks may have enhanced the strength of the reduced compacts.

Jul 11, 2011

By T J. Callaghan

The Avebury nickel mine in Western Tasmania is a disseminated nickel sulfide deposit hosted in intensely metasomatised Cambrian ultramafic resulting from later Devonian granite related hydrothermal activity.Variable metasomatism of the ultramafic has formed two distinct gangue mineral assemblages. Less metasomatised ultramafic is comprised of fine grained black antigorite with minor disseminated chromite, magnetite and pentlandite. Intensely metasomatised ultramafic is altered to a pale grey or green, coarsely crystalline tremolite/actinolite and diopside assemblage with minor magnetite, chromite and sulfides. Both gangue mineral assemblages are frequently intermixed in ore grade mineralisation.The bimodal gangue of either serpentinite or metasomatised ultramafic presents challenges to drilling, mining, resource estimation and mineral processing as they possess very different physical properties. Mineralised serpentinite has a mean bulk density of 2.8 g/cc and the ultramafic skarn a mean bulk density of 3.2 g/cc. Physically, the ultramafic skarn is hard to break percussively creating difficulties in the crushing circuit and reducing mine development rates. However, it is non-abrasive and grinds readily, resulting in increased diamond drilling rates and increased mill throughput. Conversely the serpentinite gangue is softer and breaks easily resulting in accelerated development rates and crushing circuit throughput. However, its fibrous nature reduces grinding efficiency, increasing bond work indices and reducing diamond drilling rates.Predicting the ratio of serpentinised to metasomatised ultramafic is possible through use of the resource blockmodel, assisting mine scheduling, predicting mill throughput rates, energy consumption and grade control drilling rates.CITATION:Callaghan, T J, 2017. Challenges of bi-modal gangue mineralogy in mining geology, in Proceedings Tenth International Mining Geology Conference 2017, pp 23–26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By C Bartle

In many operations the use of less electrochemically reactive grinding media in the first grinding stage (for example, rod milling and high aspect ratio SAG milling) is rarely considered. Therefore, in reality a plant may inadvertently be using a 'mixed' media charge. That is, whilst employing inert grinding media during secondary grinding, electrochemically active forged steel grinding media may be used in the primary grinding stage. This paper discusses the impact of such a circuit on the pulp chemistry and flotation response of a refractory gold ore. The Wiluna concentrator has two grinding circuits operating in parallel. Line 1 operates a single ball mill in closed circuit with cyclones, and utilises high chrome grinding media, while the second circuit (Line 2) consists of a rod mill (with forged steel rods) in series with a ball mill, which also utilises high chrome grinding media. The cyclone overflows from both circuits are combined to feed a sulfide flotation circuit. Pulp chemistry surveys were completed around both grinding circuits, and laboratory flotation tests were conducted on the cyclone overflows. The results demonstrate clearly that the rod mill/ball mill circuit operated at significantly lower Eh and dissolved oxygen values, while the percentage EDTA extractable iron was considerably higher, when compared to the single stage ball milling circuit. These variations in pulp chemistry had a marked negative impact on the laboratory rougher flotation response, and suggests that plant performance may be affected.

Jan 1, 2008

By A Fowler

The unpredictability of the location, grade and width of narrow-vein deposits presents difficulties for mine geologists and engineers attempting to estimate, schedule, forecast and mine their deposit profitably. This unpredictability stems not only from the grade distribution within a vein, but also the irregularity of vein geometry in three-dimensional (3D) space. Traditional deterministic methods of modelling vein geometry do not account for the inherent variability of the veins, resulting in significant errors when using limited drill hole information. This paper presents a probabilistic method of modelling narrow-vein deposits using sequential gaussian simulation (SGS), which can quantify this variability and improve production forecasts. Vein geometry, thickness and grade are simulated to provide a number of different equi-probable realisations that each honour the drill hole and face sample input statistics. An example is presented from the Augusta narrow-vein Au-Sb mine in central Victoria, where the simulation results are validated against the input data and survey pick-ups of the veins along ore drives.

Aug 22, 2011

By Anderson DR, Tassell G

A major environmental impact study carried out in the sand dunes of eastern Cape York used image analysis of remotely sensed data to both select sites for ground investigation and categorise the different ecological units present. The approach adopted was particularly suited to the type of environment in question and allowed a high degree of quantification, at a high level of confidence, at costs several orders of magnitude less than conventional Methods.

Jan 1, 1987

Blasting is at first sight a simple operation. Blastholes are drilled in a suitable pattern, primed, charged with explosives, stemmed and finally the blastholes are connected together to give the appro- priate initiation sequence. In practice the action of the explosive takes place in the interior of an opaque rock mass and only the external faces of the rock mass to be blasted can be easily observed. The mechanisms of blasting cannot be observed directly and must be inferred from observations of the free face and meas- urements of particle movement made by sensors grouted into holes in the rock. Explosives react very rapidly, in some microse- conds and any instrumentation of a blast must have an appro- priate response time. In many mines several rock types can be encountered during production. Several different methods of blasting may be necessary to cope with changes in rock types espe- cially if weak rocks are found in the final limits. This also makes it difficult to be sure of getting a large enough volume of rock to perform a series of reproducible experiments. While there appears to be agreement on the mechanism of blasting it is unlikely that a detailed understanding of how all the variables that can be encountered in practice affect blasting. The ease of assessment of the results of blasting depends on the criteria used. It is easy to isolate, measure and count over- size boulders. It is however difficult and costly to get a complete fragment size distribution. Methods used to assess blasting can vary significantly from site to site and the ways in which data are collected, presented and analysed will vary making compari- son of blasts at several locations very difficult. The definition of an optimum blast can also vary with the type of blasting. The muck-pile profile and fragmentation will be different for a dragline to that for a truck and shovel operation. In order to be able to assess blasting the mechanism has to be understood. Th rock and explosive properties considered rele- vant to blasting can then be determined. This paper discusses the generally accepted mechanism of blasting. The on-site observa- tions to assess blasting are-then listed. The mechanism of blast- ing can also be modelled and the use of modelling to optimize hlaetina ie thPn Aiernccarl

Jan 1, 1988

By N Yarahmadi

Characterization of pore pressure is critical for appropriate design of tailings dams. Furthermore, if seepage rates through tailing embankments increase unexpectedly or become uncontrolled, undesirable conditions may prevail to progress piping or internal erosion that could lead to the dam’s instability or ultimate failure. A three-dimensional seepage analysis was performed on a tailings dam using finite element method to find the rate of seepage and pore water conditions in the embankment and foundation. The results were then compared to a conventional two-dimensional seepage analysis carried out on the typical cross section of the embankment and the field data acquired from the instrumentation system. Considering the monitoring data, comparison of seepage analyses results for the two and threedimensional models, showed that the results of the conventional two-dimensional seepage analysis are significantly underestimating reality. Relying on two-dimensional seepage analyses might result in underestimation of seepage rates and impact the safe operation of tailings dams. Similarly, unrealistic prediction of pore water pressure conditions, based on simplified seepage analyses, can lead to overestimation of the rate of strength gain of material and consequently safe embankment raising rates.

Jul 1, 2021

By A B. Jahed, Ö Aydan, T Ito

In this study, the authors compiled some case history data and present some typical examples of rock slope stability issues in Afghanistan with a special emphasis on Kandahar region and categorise rock slope failures according to the principles of modern rock slope engineering. The slopes considered involve rock-cut, natural rock slopes mainly. The effect of structural geology and discontinuous nature of rock mass on both slope-cuts and natural rock slopes is taken into account and some preliminary assessments on the stable and unstable rock slopes are presented. Furthermore, the seismic effect on their stability is also considered. It is also pointed out that similar issues could be observed in open pit mines, which may be exploited in years to come.

Nov 29, 2022

By C R. Ure

To substantially reduce, if not eliminate, carbon dioxide (CO₂) emissions from ironmaking it is necessary to convert from blast furnace (BF) ironmaking using coking coal as the reductant to direct reduction (DR) ironmaking using hydrogen (H₂) and green electricity. Currently, almost all natural gas (NG) based direct reduced iron (DRI) production utilises iron oxide pellets in shaft furnaces, as opposed to fines in fluidised beds. Also, these pellets are ordinarily produced from high-grade magnetite concentrate, rather than hematite and goethite with typically higher gangue contents. The use of high-grade magnetite concentrate is driven by the preference to melt DRI in conventional electric arc furnaces (EAFs), thereby avoiding the basic oxygen furnace (BOF) for making crude steel (CS). However, in replacing BF with DR ironmaking it is not economically feasible to source enough high-grade magnetite to replace the lower grade hematite and goethite currently consumed. That is not to say that hematite and goethite, or even low-grade magnetite, cannot be used in DR ironmaking. However, their higher gangue content, resulting in higher slag production, requires that the EAF producing CS be replaced with a submerged arc furnace (SAF) that will produce pig iron (PI) for the BOF as does the BF. Here, critical issues to be addressed are, what are the technicalities in replacing high-grade magnetite concentrate with hematite and goethite and NG with H₂ in DRI pellet production and melting? This paper summarises certain relevant published information on DRI pellet research, test work and production together with relevant information on Pilbara ores. It attempts to illustrate the inter- relationship of composition and processing conditions on DRI pellet properties. It is intended to serve as a rudimentary guide to understanding the complexities of formulation, testing, evaluation, production and goethite and offer insight into this challenge.

Sep 18, 2023

By M Morey

Ok Tedi Mine is located eighteen kilometers from the Irian Jaya border in the Star Mountains, Western Province, Papua New Guinea. Sequential flotation concentrators produce a copper / gold concentrate for market, and a pyrite concentrate for environmental containment, with low sulphur tailings from the pyrite flotation sequence being discharged to river. Strict sulphur assay targets are set for the riverine discharge. Current porphyry and skarn ore blends from open pit operations at Mt. Fubilan will cease by 2017. However, drill cores indicate an economic ore body in the skarn ores surrounding and below the current pit limits. With proposed mining from a western pit wall ‘cut back’ and an eastern pit wall underground operation, potential for ore ageing in sub level cave underground stockpiles is apparent. With little information in the literature, Ore Ageing test work at prefeasibility level consisted of multiple one tonne stockpiles of -50 mm crushed rock. For the bankable feasibility study, a successful test work program was implemented utilizing 40 tonne ROM ore stockpiles composed of exposed pit extensions of future ores. Realistic ageing profiles of Skarn ores were obtained from one tonne monthly samples subjected to laboratory testing. Test work outcomes included:• Similar ore ageing profiles from both the pre feasibility study (PFS) and feasibility study (FS) programs, suggesting ore susceptibility to oxidation has greater effect in ore ageing than rock size for Ok Tedi skarns. • Laboratory rougher flotation of pyrite showed significant variation in sulphur recovery rate, suggesting three classes of pyrite floatability.• Laboratory rougher flotation of both copper and pyrite for up to 19 months ore ageing from 11 stockpiles, suggested three stages in the ore ageing process.

Aug 8, 2011