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Entry of personnel under a vertical raise bored hole is not standard practice in Australia. Where access is required below a rise, mining operations must be confident that they understand the capacity of the ground control specified and installed. Physical modelling was conducted on Callie mine to evaluate the performance of 5 mm steel wire weldmesh secured to the base of a vertical raise bored hole of 1.4 m diameter. Joint orientation data was used with Unwedge to calculate a series of potential wedges likely to form within the rise. The mass of the most likely wedges were then replicated by collecting rocks in 5 kg increments (¦10 per cent), which were allowed to freefall onto installed mesh at the base of a 40 m vertical rise. The results indicate that two sheets of mesh can retain a freefalling rock of at least 20 kg mass although rupture of strands can result. This paper outlines the test conditions, expected results based on theoretical calculations and actual outcomes of the testing.

Nov 25, 2010

By L Boczek

The term Engineer of Record (EoR) is commonly used in North America and South Africa to define the responsible person for the design, construction and operational phases of a tailings storage facility (TSF). Recently, this role has been elevated in prominence within Australia, but what does it really mean? Recent updates to international TSF guidelines suggests appointing an EoR is good practice, but where does the responsibilities of the EoR start and finish. Interestingly, both Samarco and Mount Polley failures had active EoR’s in place. This suggests that nominating an EoR alone, is not the full answer to mitigating the potential for a TSF failure. Appropriate construction and operational practices are key to the success of the design of TSFs, where all too often, operators ignore the operating plans developed by the designer. To be successful, a key consideration of the EoR role, is involvement in the operational phase of the TSF. This requires ‘buy-in’ from the mine managers and a change in the way TSFs are perceived by site. This paper explores how the roles and responsibilities of the EoR can assist in improving governance of TSFs if implemented effectively and what role the client has to ensure the success of the EoR.

Jul 1, 2021

By B Walsh, M Cattani, S Verpaele

With the increasing sophistication of real-time sampling devices for occupational hygiene exposure assessment, research to objectively assess their performance is a priority. Using real-time monitoring equipment has several advantages over established gravimetric sampling methods, particularly their immediate results, lower overall long-term costs and no laboratory analysis costs, which are appealing to the mining industry due to the ongoing occupational hygiene monitoring programs required by the various regulatory agencies.

Apr 16, 2024

By M Z. Abzalov

Drilling mineral sand deposits has specific challenges, which are different from drilling hard rock deposits: Drilled sequences are represented by non-consolidated free-flowing sands to semi-consolidated clayey sands and indurated layers. Valuable heavy minerals (ilmenite, rutile, zircon, leucoxene) have an average density of 4.6 g/cm3, which is significantly heavier than the hosting sand matrix; mainly represented by quartz (density = 2.6 g/cm3). The large difference in the mineral densities can result in sample segregation in the drilling rods and capturing devices causing biased composition of the recovered samples. The drilled strata can contain beds of consolidated sediments, hard pan lenses and concretions. Therefore, chosen drilling equipment should be flexible and permit a switch from drilling the free-flowing sands to hard rock drilling. Thickness of the sand hosted mineralisation varies from several metres to more than 170 m. Mineralisation is distributed above and below the water table. Evaluation of the mineral sands deposits is based on hundreds of drill holes and many thousands of samples, therefore drilling methods should be fast and cost effective. The drilling methods commonly used for mineral sand deposit evaluation, include aircore, triple tube diamond and sonic; including its variants, such as vibrocore drilling technique. The ability of the studied drilling techniques to properly address the above listed challenges in mineral sand deposits, whilst maximising the quality of the obtained samples has been compared in three deposits: Corridor Sands (Mozambique), Richards Bay (Republic of South Africa) and Fort-Dauphin (Madagascar).This study has shown that aircore samples tend to be negatively grade biased, underestimating the heavy minerals content, in particular when drilled intervals are located below the water table. Triple tube diamond core method can produce non-biased samples. However, results can be marred by incorrectly chosen drilling mud. Sonic drilling is a relatively new technique based on a high frequency vibratory technology. It is the only production drilling technique that allows a continuous relatively undisturbed sample of unlithified sands to be obtained. The main limitations of this technology preventing its wider use for developing mineral sand resources are the relatively high drilling costs, in particular when the depth of drilling exceeds 100 m, and speed of drilling advance.

Oct 5, 2011

By A Winchester, D Grant

The massive 1100 Orebody in Mount IsaÆs X41 Copper Mine has been extracted over the last 40 years form north to south utilising sublevel open stoping methods.De velopment has continually stepped ahead of production to provide access to new primary stoping blocks. The remaining secondary pillars contain stopes with one, two or three fill mass exposures and were constrained by access requirements and stope extraction turnaround time.The remaining southern mining areas consist of large 40 m wide by 300 to 400 m long east-west transverse pillars that have been left to provide access for ventilation and service requirements. Three large transverse cross-cuts or transverse pillars û 4180 x/c, 4010 x/c and the Panel pillar now remain. The 4180 x/c was the last major transverse pillar to be successfully broken.This transverse pillar is being extracted in a retreating sequence, creating 3SLOS stopes due to the surrounding backfilled stopes.In recent years the extraction of the first, and most critical, stopes in the transverse pillars have resulted in large changes to the induced stress field. This paper describes the extraction of the 1.1 million tonne stope P418 in the 4180 x/c pillar.T echnical challenges that were faced and how they were overcome to allow for the successful extraction of the stope are described.Critical to the success of the P418 stope extraction were the rehabilitation methodology used; extraction strategy modifications to address deteriorating ground; mass firings with multiple directional changes; managing the exposure of backfill of variable strengths; and geotechnical monitoring prior to, during and after extraction.

Jan 1, 2005

By R Kerrich

Early-Archaean (3.26 Ga) volcanogenic massive sulphide (VMS) deposits located within the low strain and sub-prehnite-pumpellyite metamorphic-grade Strelley greenstone belt, East Pilbara, Western Australia, contain exceptionally well preserved sulphide textures which are directly analogous to those of sulphide chimneys formed by black smokers at present day submarine hydrothermal vents. The VMS deposits are associated with seafloor alteration zones in and below silica-carbonate laminites, at the top of tholeiitic to calc-alkaline intermediate and felsic rocks. VMS mineralisation comprises stratabound Zn-rich sulphide lenses with significant Cu and barite, and variable Pb and Ag, above Cu-rich stringer zones, all of which are similar to Phanerozoic polymetallic or Kuroko VMS deposits. Sulphide-sulphate mineralisation implicates hydrothermal discharge into sulphate-bearing ocean waters, ruling out a globally anoxic Archaean hydrosphere. The volcanic rocks and co-magmatic sub-volcanic intrusion hosting the VMS deposits are characterised by the conjunction of LILE>LREE>HREE, and Phanerozoic La/Yb with negative normalised anomalies of Nb, P and Ti, consistent with derivation via subduction zone hydrous metasomatism fusing the mantle lithosphere.

Jan 1, 1995

By Z Lianbi, Z Yibin, Z Youhong, P Bin

Without adequate soil available, it is difficult to rehabilitate a large area of acid mine waste dump with sustainable plant communities, which has a strong potential acid generation. In the present project, paste tailings capping method has been put forward to reconstruct plant ecosystem on acid mine waste rock dump. This rehabilitation method uses paste tailings as capillary break and plant growth media. The tailings used contained 26.3 per cent of particles of less than 20 ¦m which satisfy the requirement of grain of paste tailings preparation. The tailings are not acid- producing materials. In addition to Cu, total contents of Zn, Pb, Cr, Cd, As and Ni in tailings are lower than those in local soil. Paste tailings concentration 70 per cent ~ 72 per cent was prepared by concentrating ten per cent tailings by using polypropylenecrylic sodium as flocculation. The potential pollution risks are low by using paste tailings as capillary break layer. Plants directly grown in the tailings did not particularly accumulate Cu, Zn, Pb, Cr, Cd, As, Ni in roots, stem and leaves, which were 0.01 ~ 1.6 times of those grown in soil.CITATION:Yibin, Z, Lianbi, Z, Bin, P and Youhong, Z, 2012. Study on paste tailings capping ecology reclamation on acid mine waste rock dump, in Proceedings Life-of-Mine 2012 , pp 243-246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

Mineral Processing Engineering Education in China - Bringing up the Engineering Diathesis and Design Competence of the College Students

Sep 13, 2010

By J M. F Clout

Geological, textural and mineralogical classification of iron ores is routinely conducted by mine and exploration geologists on reverse circulation percussion, blasthole cone and bulk samples for grade control, defining ore and waste, determining lump:fines ratio and predicting downstream processing characteristics. Classification is based on physical hardness, colour, streak and other visual characteristics. However, logging is generally restricted to the five to 20 per cent of chips above about 2 mm. This means that most of the sample is too fine to be reliably logged for anything but colour or streak and the textural types must be inferred from other information. A recently developed software package called æRecognitionÆ allows automated identification and classification of iron ore textural types and gangue on a particle basis in polished section down to 0.01 mm using processed digital images. It is not designed to be used as a routine logging tool, but is applicable where higher definition is required at the resource evaluation stage on selected percussion, drill core or bulk samples. æRecognitionÆ processes data obtained after optical image analysis of fine iron ore samples. It contains several parts, like æRecognitionÆ, æCompositionÆ, æLiberation by Total IronÆ, æLiberation by PhasesÆ and æStatisticsÆ, which allow vast and diverse information to be obtained about the iron ore samples being studied. Identification and classification of the textural type of each particle is performed according to the CSIRO-Hamersley Iron Ore Group Classification Scheme. The recognition procedure encompasses a good knowledge of different ore types and a logical knowledge tree, managing fuzzy boundary problems and the potential for a few different ore types in the same particle to be considered. This new technology introduces strict criteria to make the process of identifying particles more objective. Automated recognition standardises the identification procedure and significantly saves time. It enables users without a strong background in mineralogy to perform accurate texture identification. The æRecognitionÆ package has a modern user-friendly interface and Word compatible output. The combination of all the features mentioned makes the package a convenient tool for detailed studies of fine iron ores.

Jan 1, 2005

The Effect of Bulk Iron Concentration on the Copper Activation of Sphalerite at pH 9

Sep 13, 2010

By W Y. Kim, Y B. Kang, Y J. Park

The phase equilibria in the Al2O3–TiOx system were investigated in wide ranges of temperature and oxygen partial pressure: 1300~1600°C and 10-16.6~10-8 atm, respectively. The equilibrium phases and their compositions were identified using X-ray diffraction (XRD) and electron probe microanalysis (EPMA), respectively. Most noticeably, a wide range of pseudobrookite solid solution was found in equilibrium with almost pure alumina. At each temperature, the cationic ratio expressed as RTi = nTi/(nAl + nTi)) of the pseudobrookite solid solution showed a noteworthy dependency on the oxygen partial pressure. This resulted in the formation of a broad range of pseudobrookite solid solutions, ranging from Al2TiO5 (RTi = 1/3) to Ti3O5 (RTi = 1.0). Complete miscibility within the pseudobrookite solid solution was observed at 1600°C, with only a minor miscibility gap becoming evident below 1500°C. Based on the results obtained in the present study, the behaviours of Al2TiO5 pseudobrookite have implications in two key domains: (1) understanding changes in the physical properties of the materials, and (2) elucidating the evolution of Al–Ti complex oxide inclusions in liquid steel which can deteriorate the steel cleanliness.

Aug 21, 2024

Marble deposits of dolomitic variety are available in large quantities in India and for extracting these deposits diamond wire saw cutting machine is mainly used. Cutting performance of the diamond wire saw machine depends on rock parameters, machine parameters and operational parameters. Rock parameters related to physico-mechanical properties, such as, compressive strength, tensile strength, shear strength, modulus of elasticity and abrasion resistance of marble play role in determining cutting rate and beads wear rate. Thus, this study was undertaken to determine the relationship between different physico-mechanical properties and cutting performance. This work also aimed at enhancing the cutting performance of diamond wire saw in dolomitic marble deposit. Study was conducted in the field at three different zones having deposit of soft, medium hard and hard dolomitic marble. During the study, cutting rates and wearing of diamond beads were recorded in the field. Physico-mechanical properties were determined in the laboratory. The results obtained were subsequently evaluated by using statistical analysis. Study revealed that these properties of marble play a significant role in the performance of diamond wire saw machine. Predictive equations for the wearing of diamond beads and cutting rate were developed based on regression models. Results of this study will be of ample use for operators of wire saw to achieve maximum cutting performance and for manufacturers in designing the diamond beads.

Dec 6, 2010

East Otago gold deposits are hosted in Otago Schist that is the metamorphosed equivalent of Permian-Triassic Torlesse terrane greywackes. Relatively undeformed Torlesse sequences in Canterbury have <l m - 50 m bedding, with c. 500 m - l km and c. three kilometre scale units, typically either: 1) thick-bedded, massive, sandstones; 2) thin-bedded sandstone-argillite flysch; or 3) siltstone- or argillite-dominated units. Such lithological layering in Otago was intensely folded, deformed, and overprinted by metamorphic fabrics during Jurassic-Cretaceous regional metamorphism. Although primary sedimentary structures can no longer be recognised, a æghostÆ lithological variation is still present in Otago represented by psammitic (sand-derived), interlayered (sandstone-siltstone derived) and pelitic (siltstone-mudstone derived) schist. Lithological æunitsÆ in the schist are typically either 20 100 m or c.1 - 2 km thick, and are oblique to faults and shears hosting gold mineralisation at Macraes, Barewood, Nenthom, and Oturehua. Lithological variations and folds in lithological units are important in the along-strike distribution of gold in these deposits, and in the development of relatively high-grade pods and shoots at l00 m - 1.5 km scales. Ramps, flats and step-overs (known to be locally important for controlling mineralisation) are commonly located at lithological boundaries, presumably by local refraction of faults or shear zones as they propagated through folded stratigraphy. The various lithologies have also responded differently to deformation, causing variations in permeability that affected the penetration of mineralising fluids. Mapping lithological variations in barren host-rocks, either directly+ by fieldwork or indirectly by aerial geophysics, is a key to understanding and predicting the distribution of gold at mine and deposit scales.

Jan 1, 2001

By A Vigar

Siliceous float sampled in the Wafi River by CRA Exploration in 1977 assayed 22 g/t Au and 89 g/t Ag. Follow up in 1979 led to the discovery of outcropping mineralisation now known as Zone A. Soil sampling in 1980 and 1982 outlined a 350 m by 400 m area of >1 g/t Au at Zone A and smaller areas at Zones B, C and D. Thirty-one diamond holes were drilled between 1983 and 1986. Elders Resources continued evaluation of Zone A under a farming agreement between 1988 and 1990. Mineralised diorite porphyry was discovered in 1990 by drilling conceptual targets 500 m to the NE of Zone A. Evaluation of this copper-gold porphyry became the main focus of exploration for the next five years and a substantial resource was outlined within a single, discrete body. A review of the paths to project development in late-1995 highlighted the need for increased resources via a second mineralised porphyry and/or an additional resource of Zone A size to make the project viable. It was concluded that the greatest immediate potential for increasing the resource inventory was at Zone A itself where the mineralisation was open in all directions. Detailed mapping and drill core logging lead to the geologic and structural models being revised in early-1996. The objectives of the 1996 drill program were to extend the Zone A resource, to test for continuity of mineralisation westwards to Zone B, to better define the controls on gold mineralisation and to delineate high-grade blocks amenable to selective mining by infill drilling and 3D orebody modelling. The last drill hole of 1996 intersected 30 m at 4.6 g/t Au from 273 m in WR147, deep in the western limit of Zone A. This intersection gave impetus to continue drill testing towards Zone B. In April 1997, hole WR154 was drilled 100 m to the west of WR147 and intersected 20 m at 8.5 g/t Au and 70 m at 11.0 g/t Au at similar depths near the diatreme contact. Drill hole WR155 was then drilled 100 m to the west of WR154 and intersected 86m at 5.7 g/t Au and WR159 drilled 100 m to the south of WR154 intersected 36 m at 9.2 and 50 m at 4.4 g/t Au. A significant zone of essentially blind, high-grade gold was discovered beneath the dipping flank of a poorly mineralised diatreme in what became known as the Link Zone. The long history of evaluation has been driven by the conviction of a dedicated team that a mineralised system of the size and complexity of Wafi with strongly anomalous gold in outcrops over the entire Mount Golpu area must contain economic mineralisation hidden within it. The keys which redefined the direction of exploration and lead to the discovery of the blind, high-grade gold Link Zone were, in our view, the critical review of the project status, detailed geological and structural studies to define clear exploration targets and the necessary funding and persistence to carry this through.

Jan 1, 1999

By A E. Annels, G F. Johansen, B W. Cuffley

Nuggety gold-quartz reefs are characterised by localised, high-grades and in many cases coarse free-gold. Geometrical and grade complexities are often observed. The high-grade regions are generally erratic and have a low continuity; though may make the deposit economic. Viable grades are generally contained within discrete oreshoots, which are surrounded by barren/low-grade material. Drilling is an effective measure of geological continuity, however grade distribution can only be reliably obtained from underground development and bulk sampling. In general terms, only an inferred resource is likely to be estimated from surface drill data alone. Underground development, further drilling and probably bulk sampling will be required to delineate inferred and indicated resources. Closely spaced development with bulk sampling is likely to be the best way to determine a probable reserve. The resource evaluation process must driven by a clear geological model that should attempt to understand the controls to reef geometry and grade distribution. Geological interpretation has traditionally been undertaken in two-dimensions, though computer software is now being used to produce three-dimensional models. Grade interpolation has generally been undertaken using classical methods, typically weighted averages, zone of influence weighting and polygonal/sectional blocks. Tonnages can generally be calculated from diamond drill and development information with a reasonable degree of confidence. Grade is much more difficult to define with confidence because of its highly erratic and discontinuous nature. To account for variability it is recommended that a best estimate be reported within a grade range, as this more accurately reflects the uncertainties involved. Reporting should be undertaken within the framework of the JORC code, but should involve special consideration of grade reliability.

Jan 1, 2000

Discrete Element Method - Computational Fluid Dynamics Modelling of Flow Behaviour in a Stirred Mill - Effect of Operation Conditions

Sep 13, 2010

By P B. Card

"The website www.economicevaluation.com.au, which had its origins at the Project Evaluation Conference 2009, provides a free way for industry professionals to teach themselves economic evaluation. At its core is a set of fast-moving modules and three worked examples.The website recognises that economic evaluation is a discipline with a hierarchy of three levels:decision-makingevaluating the project/businesshands-on modelling.There are a set of modules for each level that describe the concepts and activities in detail. These emphasise that the most important and rewarding work is the evaluation of Level 2. The economic model created in Level 3 is merely a working tool and should not become a sophisticated ‘trophy’ in Excel that only one or two people can comfortably use.Hands-on modelling contains three sets of practices designed to make any model rigorous and intuitive so that it can be easily understood and used by others in the project team. Even if the model develops into a long, detailed and complex workbook, it should remain easy to follow and be intuitive. The website advocates freedom to devise any architecture that best suits the project under study, but promotes rigour through the following practices:four cash streams and graphsthree architectures – concept, prefeasibility and feasibilitysix principles.The modules in the Level 2 evaluation use conversational language to describe in detail the broad range of activities needed to properly understand and characterise a project/business. It stresses that net present value is nothing more than the mathematical treatment of a whole set of opinions, is not an absolute truth and is only a fraction of the evaluation process. The modules describe in detail the range of economic metrics that should be computed and the full spectrum of equally important characterisations required to make the decision in Level 3.CITATION:Card, P B, 2016. Teach yourself economic evaluation, in Proceedings Project Evaluation 2016, pp 160–171 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By S F. Simmons

The Ohaaki Rhyolite and the Rautiwiri Breccia are two volcanic units occurring in the shallow and deep parts of the Broadlands-Ohaaki geothermal system. Alteration of these units by chloride waters results in distinct mineral assemblages that also have distinct whole rock compositions. The Ohaaki rhyolite is altered to an assemblage dominated by quartz, adularia, illite and pyrite as a consequence of silica, potassium and sulfur metasomatism. Locally, these rocks contain up to 0.5 ppm Au. The Rautiwiri Breccia by contrast is altered to an assemblage dominated by albite, adularia, quartz, illite, chlorite and pyrite in association with modest sodium metasomatism. Whole rock oxygen isotope compositions of altered rocks range between 3.3 and 7.5 ë, and are generally lower compared to their fresh rock equivalents having values of 9.5 to 10.6 ë; the result is broad pattern of lower values with increasing alteration intensity.

Jan 1, 2002

By Sans H

The geostatistical Discrete Gaussian (DG) model is demonstrated to be capable of providing an effective means of implementing change of support for Enterprise-style mineralisation and thus providing reliable global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively skewed, therefore significant deskewing of the histogram and reduction of variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced short range structures are observed in variograms. The experimental test was run for a change of support for which the variance reduction was. approximately 60 per cent. This reduction is similar to that predicted by Krige's Relationship ('the volume-variance relationship') for the practical situation of a change of support from 5 m vertical blasthole samples to 3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage relationships for a wide range of cut off grades. The experimental test indicated that, given a representative histogram and variogram, the DG change of support provides a computationally efficient and practical means of reliably assessing global mineable resources at the early stages of a mining project. Further, it allows a range of selectivity strategies to be meaningfully and comparatively considered prior to mining.

Jan 1, 1995

Alluvial mining even of shallow deposits is often economically a marginal proposition and causes significant disruption of the land surface through the need for large scale excavation. In-situ leaching using chlorine-based solutions eliminates the need for excavation, the disruption of surface activities, and may greatly reduce processing costs and improve recovery especially of fine gold. A spreadsheet model has been developed to design and analyse the economics of in-situ leaching of alluvial deposits. In-situ leaching of shallow deposits may be achieved in a number of ways including solution infiltration via perimeter ditches or the use of injection and production wells. In most instances deeper alluvials may only be processed using well systems. Two deposits are analysed in this paper. The first consists of one metre of payable wash beneath one metre of overburden. Some thirty fields per year are treated processing 450 000 BCM per year at a cut-off grade of around $4/tonne ($8/rn3 or the gold value equivalent of 0.26 gh or 0.52 g/m3). The principal costs are well drilling and labour. Sensitivity analysis indicates that doubling the throughput halves the cost. The economics of the project are relatively insensitive to reagent costs and consumptions, and halving the recovery doubles the cut-off grade. Shallow deposits treated using the infiltration ditch system may be marginally cheaper and more conveniently managed although this depends on the relative cost of digging the perimeter ditches. In a second example, deep leads with one metre of wash beneath 30 metres of overburden necessitate significant drilling and feature reduced throughputs as a consequence. In the example chosen 30 fields a year are processed for an annual throughput of 65 000 tonnes costed at around $20/tonne (1.4 g/t Au equivalent, $40 /m3). Sensitivity analysis indicates that throughput, and drilling cost per metre are not important but there is a high sensitivity to recovery and to the depth to payable wash.

Jan 1, 1992