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By O. A. Lima

Effective solids suspension is a necessary precondition for particle collection, and solids suspension is largely dependent on the hydrodynamics of the flotation cell. This study attempted to correlate the status of the suspension of apatite particles of different sizes in a Denver laboratory flotation cell versus the impeller rotational speed (N) adopted to operate the machine. The latter variable (N) influences the impeller capacity to lift the particles from the bottom of the tank and also to disperse them throughout the volume of the vessel. Such an impeller capacity can be characterized by the critical impeller speed for the accomplishment of solids off-bottom suspension (Nz) and also by the velocity of the radial water flow discharged by the impeller (U) divided by the particle terminal settling velocity (Us). This way, the status of the suspension of apatite particles inside the flotation cell can be characterized by one of three categories: ?segregation? (N/N2 < 0.60 and Us/U > 0.08); ?suspension? (0.60 = N/N2 < 1 and 0.06 < Us/U < 0.10); and ?dragging? (N/N2 = 1 and Us/U = 0.03). The range of impeller rotational speed (N), which was able to suspend the finest particles (Dp = 90 µm), was unable to suspend the coarsest particles (Dp = 254 µm). Conversely, the high value of N (N > 1,300 rpm), which is adequate to suspend the coarsest particles, may promote the entrainment of the finest particles to the froth layer.

Jan 1, 2009

The modelling of lithological domains is a critical step in mineral resource and reserve evaluation. Deterministic models rely on an interpretation of the available drill hole data and expert knowledge, but do not account for the uncertainty in the spatial extent of the lithological domains. Instead, probabilistic models based on conditional simulation can be used to map the probabilities of occurrence of the domains within the deposit, which reflect the uncertainty in their presence or absence at unsampled locations. The mineral grade model is then obtained by weighting the predicted grades associated with each lithological domain by the probability of occurrence of this domain. Such an approach accounts for the continuity of the grades proper to each lithological domain and for the uncertainty in the spatial extent of these domains within the deposit. An application to a porphyry copper deposit is presented. Keywords: spatial uncertainty; plurigaussian simulation; geological control; kriging; geostatistics.

Jan 1, 2007

By S L. Garwin

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Since the Eocene, New Guinea tectonics have been driven largely by the south-westerly-directed collision of accreted arc terranes with the northern margin of the Australian Craton, and subsequent westerly-directed transport of these exotic terranes by left-lateral strike-slip fault systems. The subduction of the Solomon Sea plate beneath north-eastern New Guinea in the mid- to late-Miocene led to magmatism and related gold-copper porphyry and epithermal mineralisation in the Maramuni arc and the formation of the Frieda River, Nena, Wafi-Golpu and other deposits.The development of the world-class porphyry and epithermal deposits in the Medial New Guinea magmatic belt, including Grasberg, Ok Tedi and Porgera, is localised by dilational zones formed about the intersections of north-easterly-trending, reactivated basement faults and north-dipping reverse faults related to the southward progression of the Papuan fold belt during the Late Miocene to Pleistocene. These deposits probably formed during short mantle-derived magmatic episodes in zones of regional isostatic uplift, which are attributed to the delamination of the lithospheric mantle beneath New Guinea.CITATION:Garwin, S L, 2015. The tectonics, geology and gold-copper metallogeny of New Guinea, in Proceedings PACRIM 2015 Congress, pp 151–164 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By M. B. C. Brandt

Focal depths of 15 tectonic earthquakes and 9 mine-related events were determined for South Africa using data recorded by the South African National Seismograph Network. These earthquakes and events were relocated by means of the Hypocenter program using direct P-waves (Pg) , critically refracted P-waves (Pn) , and first-arrival S-waves for the magnitude range 3.6 ?? ML ?? 4.4. Focal depths were first determined by means of the minimum root mean square (RMS) of the differences between the measured travel times and those predicted using the velocity model. The depths for tectonic earthquakes had a 2 km ?? D ?? 10 km range and an average depth and standard deviation of 6.9 ± 2.3 km. Depths for minerelated events ranged over 0 km ?? D ?? 7 km, averaging 3 ± 2.3 km. Next, arrival times for the additional regional depth phases sPn , PmP, sPmP, and SmP were measured. Focal depths were re-determined for the relocated epicentres, with the minimum variance (i.e. spread) of the differences between the measured travel times and travel times predicted by means of the Wentzel, Kramer, Brillouin, and Jeffreys (WKBJ) method for synthetic waveform modelling. Depth ranges were 4 km ?? D ?? 7 km (average 5.9 ± 1.2 km) and 1 km ?? D ?? 4 km (average 2.4 ± 1.2 km) for tectonic and mine-related events, respectively. The derived depths were verified for one tectonic earthquake with synthetic-to-recorded-waveform fits using the WKBJ synthetic seismogram software for the abovementioned regional phases. The focal mechanism parameters for this earthquake source were obtained from the National Earthquake Information Centre. Focal depths were estimated for nine stations by visually comparing synthetic waveform phases with recorded waveforms, ranging from 5 km to 8 km.

Jan 1, 2014

By J. Searra, M. Aboagye

"For new mining projects or for medium- to long-term areas of existing mines, drilling data is invariably on a relatively large grid. Direct estimates for selective mining units (SMUs), and also for much larger block units, will then be smoothed due to the information effects and the high error variance.The difficulty is that ultimately, during mining, selection will be done on the basis of SMUs on the final close-spaced data grid (grade control), which will then be available, i.e. the actual selection will be more efficient, with fewer misclassifications. However, this ultimate mining position is unknown at the project feasibility stage and therefore has to be estimated. This estimation is required because any cash flow calculations made on the basis of the smoothed estimates will obviously misrepresent the overall economic value of the project, i.e. the average grade of blocks above cut-off will be underestimated and the tonnage overestimated for cut-off grades below the average grade of the orebody. Similarly, unsmoothed estimates will be conditionally biased and will give even worse results, particularly in local areas of short- and medium-term planning or mining.This paper presents a case study of indirect post-processing and proportional modelling of recoverable resources designed for mediumand long-term mine planning at the Gold Fields’ Tarkwa Mine in Ghana. The case study compares long-term indirect recoverable mineral resource estimates based on typical widely spaced feasibility data to the corresponding production grade control model as well as the mine production. The paper also proposes certain critical regression slope and kriging efficiency control limits to avoid inefficient medium- to longterm recoverable estimates, and highlights the danger of accepting block estimates that have a slope of regression less than 0.5."

Jan 1, 2015

Coal has become an enormously important export industry. Owing to a range of mainly natural advantages, Australia has been able to almost treble its exports in a little over the last decade. Australia is now the world&apos;s second largest exporter and coal is now the nation&apos;s largest single export earner.Despite this very significant growth, Australia&apos;s competitive position is in jeopardy.

Jan 1, 1984

By David C. Kraft

Helical piles and ground anchors were used to meet critical design and constructability requirements for an urban forest Canopy Walk at the Atlanta Botanical Garden, Atlanta, GA. The 12-foot wide pedestrian walkway path was to be nestled among the treetops of a forest, extending to 600 ft. in length, and soaring 40 ft. high above the forest floor. Of particular concern during construction was that the foundation system for the temporary steel shoring system had to be non-invasive to the subsoil, could not damage the forest floor, trees, root systems, or foliage, and upon completion of the concrete walkway pour, could be removed, again without disturbing the subsoil. Accubrace, Inc. designed and installed all the helical foundation types, as well as provided steel braces, typically used in Tilt-Up building construction, for the walkway project. The braces, some extending to 43 ft. in length, were used to provide lateral support against wind loads for the walkway form. In addition, the braces acted as secondary support for lateral loads during the placement of wet concrete along the 600 ft. length of the walkway. Helical foundation products installed included vertical compression piles, ground anchors for tension rods, and ground anchors for the braces. The installation of the piles and anchors was particularly challenging since the forest floor elevation varied as much as 50 ft. due to the presence of a ravine. Information is provided on the subsoil conditions, required loads, design, installation, and acceptance criteria for each helical product type installed for the project. The results of vertical and lateral load tests on the helical piles in the pre-construction phase, conducted in conformance to project specifications are presented. Photographs to illustrate the nature and complexity of the project are included. The concrete pour for the walkway was successfully completed on December 12, 2009, and the walkway was opened for visitors in May, 2010.

Jan 1, 2011

A modified liquation technique was developed for recovering tin from tinhouse scruff metal or hardhead containing about 10 per cent iron and 15 per cent occluded flux, palm oil, and moisture. This was effectedby heating the scruff metal to 950&#176;C followed by rapid cooling to suppress the formation of FeSn2 and FeSn, and then subjecting it to the ordinary liquation and drossing processes of refining. By this method it was possible to recover about 83 per cent of the original tin content and, with subsequent smelting of the irony drosses, an overall recovery of 92 per cent was obtained.

Jan 1, 1969

By Woodcock J. T

A sulphide ion selective electrode (ISE) is suitable for control of sodium sulphide additions in flotation because it has a rapid response to changeS in S2- concentrations, can indicate -low concentrations at differentpH values, suffers from few interferences, and is robust enou&apos;gh to use in a pulp. Three sulphidization techniques were studied using the lSE electrode for measurement and/or control of S2- levels. Metallurgy was assessedfrom concentrate grades and copper recovery.With slug additions of sodium sulphide, sulphidizing conditions were poorly defined and reproducibility tended to be poor. Although acceptable metallurgy could be achieved by multiple additions, sodium sulphide consumption was high.Controlled potential sulphidization readily gave good metallurgy. The optimum potential of the lSE for sulphidizing was about -500 mV versus SCE, but depended on sulphidization and flotation times; suitable times were3 and 5 min respectively for three to five stages. Application of this technique to previously untested ores gave good metallurgy in a first test in spite of variation by a factor of three in the sodium sulphide requirements ofthe ores.Simultaneous sulphidization and flotation was satisfactory when conducted at an lSE potential of -450 mV versus SCE. Mixed cha!copyrite-oxide copper ores responded satisfactorily.Besides optimizing sulphidization conditions it is also necessary to optimize xanthate additions (e.g. by measuring xanthate residuals).

Jan 1, 1978

By Hu Harries

WE RECENTLY completed a study for a client, who is an applicant to export gas from the Province of Alberta, on the effects of gas export on Alberta&apos;s economy. This study was part of the client&apos;s application ?before the Conservation Board, and, no doubt, some of you are familiar with it. Submissions by other applicants in earlier hearings before the Board and before the Royal Commission on Energy, as well as claims made by parties opposing export, have also brought forward a number of other opmwns regarding possible economic effects. Ali of these studies have been on a piecemeal basis. They have dealt with particular aspects of particular applications, and only indirectly and by inference with the overall question of gas ex-port. We have prepared this paper to review the overall picture and ex-amine, as far as time permits, all sides of the question. While the paper is entitled Economic Effects of Gas Export on Alberta, we felt that the area considered should in-elude northeastern British Columbia, not only because Westcoast, the first major gas export project, is essentially a northeastern B. C. project, but because this area has historically been, from the point of view of economic, if not of political, geography, part of Alberta. In this paper, when we talk of export, we mean export from the Province or, in this case, from Alberta plus northeastern B. C. Sales to other parts of Canada have exactly the same effect on the economy of this area as l1ave sales to the United States, provided, of course, they are made on equal terms.

Jan 1, 1958

By Betty L. Gibbs

Geologically simple deposits can be modeled quickly and easily with inexpensive gridding and mapping software. Hundreds of mines around the world use RockWorks99 and Surfer 7 for generating contour maps, producing log plots and cross sections, and performing other useful geological calculations. These programs are used by many mining operations as their only modeling and graphical software or they are used in conjunction with larger systems. The investment in learning time is low and the programs produce reasonable quality results with standard computing equipment. RockWorks99 and Surfer 7 provide a good level of capability while maintaining high quality technical integrity. Both programs are used for many applications in mining, oil and gas, environmental and other fields that require analysis of spatial data.

Jan 1, 2000

By A. W. Popp

After forty years of exploration and development, the heavy mineral sand deposits of the Murray Basin are on the eve of substantial exploitation by Iluka Resources Limited, Southern Titanium NL and RZM/Cable/Bemax, whom plan to initiate mining and processing operations in 2005. A trial mining and processing operation was undertaken on the Wemen North strandline deposit in 2001-2003 by Murray Basin Titanium, a joint venture of Sons of Gwalia and RZM/Cable, which brought to light a number of mining and processing problems which have since been the subject of extensive studies and process development work. The mineralogy of these weathered strandline deposits is complex by industry standards due to the variety of the heavy minerals present, coatings on the mineral grains and the extensive weathering and alteration which has taken place during the past 50 million years. This paper provides an overview of the complex mineralogy that, in turn, dictates the processes that can be used to recover the valuable heavy minerals. The Murray Basin encompasses some 300,000 km2 and has been a depositional basin, often land locked, since the start of the Cenezoic Era. The economic heavy minerals include ilmenite, altered ilmenite, leucoxene of highly variable composition, rutile, and zircon. There are also other heavy minerals present such as cassiterite, chromite, and monazite in quantities that pose both problems and opportunities. The clay content and overburden thickness also play a major role in the selection of the deposits to be mined. Project Services Consultants (PSC) has undertaken the preparation of this paper as part of its ongoing participation in the mineral sands industry and in particular the project development activities in the Murray Basin region currently being undertaken by Iluka Resources. PSC has been involved with the mineral sands business for several years with senior staff having in excess of 30 years global industry experience. The company is well placed to provide a range of services to clients like Iluka Resources in the areas of project development, execution and strategic development and industry advice.

Jan 1, 2005

By Alex Chapman, Cam Thomas, Bryan Karney

"During the early summer of 1989, Ontario Hydro removed a concrete portion of the North Channel Dam at Crystal Falls Generating Station by blasting and excavating in marine conditions. Because of the severity of underwater blasting and because the site was in close proximity to the replacement dam, there was concern that hydraulic shock waves generated by the detonation could damage either the new dam or its control structures. This paper examines the data associated with the hydraulic shock waves generated by underwater blasting, and studies the effectiveness of an air curtain in reducing the peak pressures. In previous trials using the air curtain technique, a rule-of-thumb factor was used to estimate that only 10% of the original pressure pulse would propagate across the air curtain. However, this value had little basis in theory. A theoretical formulation of the problem by Karney in 1989 indicated a provisional value of 0.18 for this factor, but was heavily dependent on confirmation from in-field testing. Data provided by Ontario Hydro from an actual blasting procedure indicate that a more conservative value of 0.32 may be more appropriate. Thus.although the air curtain did provide considerable reduction of peak pressures, the data at Crystal Falls indicates its performance was below the anticipated level. However, due to problems with the instrumentation and some inconsistencies in the resulting data. it is recommended that this value be further refined as additional data become available."

Jan 1, 1992

By Syd Peng, W. B. Guo, F. Du, L. Yang, J. Yw. Cheng

The annual ICGCM China was initiated in 2014. Up to 2023, ICGCM China has been held 9 times. In the 9 conferences during the past 10 years, about 559 papers in 17 topical areas were presented and attendance ranged from 200+ to 400+ each conference. The 42nd ICGCM China was held in Xiangtan, Hunan, China, 10/20–10/22/2023. There were 86 papers presented in 26 topical areas. In addition, an MS and PhD Research Forum was held concurrently with 36 papers presented by MS and PhD candidates in mining engineering from 8 schools. The conference plays an important role in cultivating advanced degree student talents. In this paper, all 559 papers reviewed previously were summarized. In addition, the 42nd ICGCM China is used to illustrate the current and future development trends of coal mine ground control in China. It summarizes the 122 papers (including 36 MS and PhD forum papers) grouping into, and in terms of, 26 topical areas. In addition, its unique and innovative subject areas, short summary of developments as well as conference strengths and shortcomings will also be presented.

Jun 25, 2024

By A G. Thompson, E Villaescusa, A De Zoysa, J R Player

Ground support performance is critical to the safe and economical extraction of ore. This is particularly important for mass mining extractions at great depth, which are currently being considered by a large number of mining companies worldwide. As the in situ stresses concentrate around critical excavations, failure occurs at the excavation boundaries and ground support is required for the excavations to remain safe and accessible for their intended lifespan. Ground support consists of reinforcing elements that are installed within the rock mass to modify its internal behaviour (generally to within one excavation radius) and surface support elements that are installed at the exposed boundaries to retain the failed pieces of rock. For surface support to be effective, the loadings need to be transferred to the reinforcing elements; however, the combined performance of rock bolts and mesh is poorly understood in terms of the energy dissipation capacity available for a typical ground support scheme implemented at most mass mining operations.Over the last 15 years or so, a large number of large-scale laboratory experiments have been completed at the Western Australian School of Mines (WASM) Dynamic Test Facility for reinforcement systems and surface support systems loaded separately. The objective of more recent testing has been to establish the combined energy dissipation capacity of typical and enhanced reinforcement systems combined with mesh surface support. Total energy dissipation has been separated into energy dissipation attributable to the reinforcement and to the mesh. The results of the tests are presented and compared with the existing WASM design demand and capacity guidelines.CITATION:Villaescusa, E, De Zoysa, A, Player, J R and Thompson, A G, 2016. Dynamic testing of combined rock bolt and mesh schemes, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 789–798 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By E. M. Shemang, C. E. Suh, L. Mbinkar, University of Yaounde

"Two iron deposits within the Precambrian mineral belt of Cameroon are described in detail for the first time: the Archean Metzimevin replacement iron deposit enclosed in Fe-enriched itabirite, and the Proterozoic granite-hosted, shear zone-related Mayo Binka magnetite deposit. In the Metzimevin de¬posit, quartz is corroded and microplaty hematite overprints martite-textured hematite. The Mayo Binka massive magnetite veins show evidence of deformation in magnetite (fracturing and microbrecciation) and in overgrowths of specular hematite (mechanical twinning and undulating extinction). The magnetite is partially replaced by hematite (martitization) and goethite. Ores from both deposits have >88% total Fe2O3 and low contents of contaminants such as SiO2, Al2O3, MgO, CaO, P2O5, and TiO2. They are also poor in Cu, Pb, Zn, V, Cr, and Ni. The Metzimevin massive hematite is characterized by an accentuated light rare earth element depletion relative to the Fe-enriched itabirite. It is suggested that the Metzimevin iron deposit is the result of hypogene leaching of gangue minerals from, and further hematitization of, an itabirite protore. Although the genesis of the Mayo Binka massive magnetite is unclear, it is spatially related to Neoproterozoic granitic rocks. The data allow some comparison of these little known, but pot¬entially economic iron deposits, with some of the world’s better investigated deposits, and are useful to the exploration efforts for iron ore currently underway in Cameroon and the Central African subregion.Deux gisements de fer de la ceinture minérale Précambrienne du Cameroun sont ici décrits en détail pour la première fois : le gisement de fer Archéen de Metzimevin formé par remplacement et encaissé par des itabirites enrichies en Fe, et le gisement de magnétite Protérozoïque de Mayo Binka as¬socié au cisaillement dans un granite. Au gisement de Metzimevin, le quartz est corrodé et de l’hématite en microplaquettes se développe au dépends de l’hématite a texture martitique. Les veines de magné¬tite massive de Mayo Binka présentent des évidences de déformation dans la magnétite (fracturation et microbréchification) et dans les surcroissances d’hématite spéculaire (Macles tectoniques et extinction ondulante). La magnétite est partiellement remplacée par l’hématite (martitisation) et par la goethite. Le minerai des deux gisements contient >88% de Fe2O3 total et un faible contenu en contaminants tels que SiO2, Al2O3, MgO, CaO, P2O5, et TiO2. Il est également pauvre en Cu, en Pb, en Zn, en V, en Cr et en Ni. L’hématite massive de Metzimevin est caractérisée par un appauvrissement relatif en terres rares légères relativement à l’itabirite enrichie en Fe. Il est suggéré que le gisement de fer de Metzimevin résulte du les¬sivage hypogène des minéraux de la gangue ainsi que de l’hématitisation poussée d’une préconcentration de fer dans l’itabirite. Bien que la genèse de la magnétite massive de Mayo Binka demeure obscure, elle est spatialement associée aux roches granitiques Néoprotérozoiques. Ces données permettent de comparer ces gisements de fer peu connus et potentiellement économiques avec certains des gisements mondiale¬ment mieux connus, aidant ainsi les efforts d’exploration présentement en cours en Afrique de l’ouest et au Cameroun."

Jan 1, 2008

By Stephen Chung, Graham Mustoe, Joe Haid

In an open cast coal mining operation, a 305 m (1000 ft) long by 49 m (160 ft) thick overburden cast blast can produce more than a million cubic yards of broken muck that needs to be removed before the coal recovery process can start. In the Powder River Basin of Wyoming, it is common to see 30 to 40 percent of the overburden cast to a spoil that does not require rehandling with heavy equipment. Therefore, the higher the percent cast, the better the cast blast is rated. However, depending on the shape of the muck profile, there is often 20 to 30 percent of the muck standing in front of the high-wall. This portion of muck would require a number of dozers to push down to the dragline pad level. From the mine operator point of view, it is believed that for a given muck profile, there should be an efficient dozer pushing method such that a dragline pad can be developed in the shortest time. As a tool for analyzing this dynamic problem, a 2-D discrete element model, i-PushTM, has been developed to simulate a dozer pushing operation. This mechanistic model takes into account the dozer blade geometry, the dozer operating procedure (e.g. cut-depth, blade fill distance, forward and reverse speeds at specific slope angles), material density and cohesion. To demonstrate how i-PushTM can be used to help determine the most productive push routine, this paper presents three dozer push methods to compare the effectiveness of pushing at 3:1, 4:1 and 5:1 push angles.

Jan 1, 2006

By J. Samir

The objective of this study is to simulate the isothermal filling up of moulds by a RTM process when adopting CV/FEM and VOF method and when also taking into account the presence of obstacles coupled to the effect of the thickness and reinforcement layers variation. The codes developed intended to ensure an optimal positioning of the injection points and of the vents and also to determine optimal injection pressures, in order to minimize the cycle times. These codes use a mesh generator proper to the team, allowing a discretization of the domain in triangular unstructured elements, with the possibility of a local refinement and inserts inclusion.

Jan 1, 2009

By Y. Zhoa

The surface morphology of materials is of fundamental importance to many surface related applications, such as wetting, friction, reflection, drag, and adhesion. Various approaches for micro/nano patterning atop polymer surfaces have been proposed in recent years. However, a cost effective technique is still highly in demand. In this paper, we demonstrate a novel but rather simple and generic approach for surface micro/nano patterning using shape memory polymers (SMPs). Different types of novel patterns are realized and their 3-D surface features are quantitatively analyzed by a PLµ Confocal imaging profiler.

Jan 1, 2010

Hydrogen and carbon monoxide reduction data were obtained on pelletized materials of the type currently being prepared commercially in Australia.Pellets, approximately 1 cm diameter, made from Deepdale, Iron Prince, and Mt. Newman iron ore were reduced by hydrogen over the temperature range 500&#176;-900&#176;C and the reduced pellets were examined by thermogravimetric, microscopic, electron probe, and x-ray techniques. After an initial time delay it was found that up to 95 per cent reduction the data could be described by a porous model where gaseous diffusion through the solid is rate controlling. Independent measurements of effective diffusivity supported the values obtained from the reduction data. Above 95 per cent reduction the rate decreased markedly due to the formation of retained wustite or fayalite.Comparison with reduction by carbon monoxide over the temperature range 750&#176;-900&#176;C showed that the rate of reduction was approximately five times slower than for reduction by hydrogen.The rate of reduction was found to be a function of the initial properties of the pellets which may account for the widely conflicting results that have been obtained with previous investigations on porous pellets.

Jan 1, 1971