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By M Field

Kimberlite pipes, as opposed to dykes, sill and secondary deposits, are the primary target for diamond exploration companies because they have simple geometries and can contain large volumes of potentially diamond-bearing ore. Once discovered, important decisions have to be made regarding the sampling of these geological entities to establish the total volume of ore present, and to define the internal geology, which can be complex in nature and controls the distribution of diamond grade. It is essential that as part of this process the uncertainty in constructed geological models are assessed. In this paper the Orapa AK1 kimberlite pipe in Botswana is used as a case study to explore a potential methodology for defining this uncertainty. The uncertainty of the rock volumes of different types can be characterised by a geostatistical approach. Geostatistical simulations, based upon a plausible representation of the geological bodies, provide different possible images of the orebody that can be considered as different realities. By testing different borehole layouts and drilling the orebody virtually on the computer, many different, but equi-probable realisations of the pipes can be produced. It is then possible to estimate the rocksÆ volumes and compare them with the actual ones. A statistical analysis of the relationship between estimation error and the number of boreholes can then be used to optimise the next sampling campaign. The rock volumes are obtained from a two-step simulation process. Firstly, the pipe geometry is simulated by means of introducing variations around the geological block model, by an original method called centre point simulation (CPS), which has been developed for this purpose. Secondly, the internal geology is then simulated within the pipe. The methodology for simulating the internal geological zones has to be adapted to the level of information and to the geological structure itself. The upper portion at Orapa AK1 is filled with sedimentary crater facies. Here plurigaussian simulation techniques can be applied that are adapted to the simulation of sedimentary facies. The central zones of the pipe are typically subvertically-oriented massive volcaniclastic deposits and breccias and the lower regions comprise a complex root zone. CPS is appropriate for these zones.

Jan 1, 2006

By G J. Zhang

The shape and particle size distribution of caved ore mass in sublevel caving were investigated in this study. The paper first reviews the main factors affecting the shape and characteristic of caved ore mass in sublevel caving and then through the experimental blast testing with cement-sand concrete models, the shape and particle size distribution of caved ore mass were found out. The experimental results indicated that the shape and particle size distribution of caved ore mass was similar to that of the drawn loose body. This finding presented a new perspective for the future study on the ore drawing theory and on the optimisation of structural parameters of sublevel caving. The structural parameters must meet the principle that the shape of the drawn body is in consistency to the shape of caved ore mass.

Jul 11, 2011

Copper-Cobalt hydrometallurgy has seen a resurgence in recent years with the development of projects in Zambia and the DRC. Many of the flow sheets are unique in their use of hydrometallurgical techniques to improve performance compared to the older types in current use. The emphasis has moved from direct copper electrowinning/stripping, with multiple stages of precipitation for removal of impurities and concentration of cobalt, to innovative use of solvent extraction and ion exchange with higher cobalt recoveries to final product. The poor quality direct electro-won copper has been supplanted with solvent extraction-electrowinning; with consequent production of LME 'A' quality metal. Many of the precipitation steps in cobalt recovery and concentration, have been replaced with solvent extraction; while the remaining precipitation stages have been enhanced with use of oxidants to improve impurity removal. Operating experience from two of these circuits has shown the benefits of the new technologies and the improved overall recovery of both copper and cobalt into higher quality products.

Jan 1, 2008

By P Sha

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Elaine Dorothy Cu-Au (REE-U) skarn deposit in the Mt Isa Inlier, Queensland, Australia is characterised by extensive metamorphic calc-silicate hornfels long before hydrothermal skarn and complicated deformation history. The deposit is hosted by the Corella Formation (1780–1740 Ma) and exhibits two phases of skarn formation in the study area – banded fine-grained diopsidic hornfels (Phase 1) and coarse-grain pyroxene skarn (Phase 2). Phase 1 skarn is predeformation and is interpreted to have been caused by the 1743–1734 Ma Burstall Magmatic Suites, whereas the coarse-grained pyroxene skarn (Phase 2 skarn) postdates the deformation and peak metamorphism events. Phase 2 skarn consists of prograde pyroxene, less garnet and titanite, retrograde epidote, REE-allanite, amphibole, biotite, and later sulfides, carbonate, quartz, anhydrite and chlorite. It hosts most of the copper mineralisation, with the REE elements occurring mostly in allanite. Titanite coexisting with allanite and Cu-Fe sulfides in Phase 2 skarn has been dated by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at 1524 ± 9 Ma (207Pb/206Pb). The ages are similar to Williams-Naraku Batholiths, which outcrop approximately 40 km to the east in the Eastern Fold Belt. In Elaine Dorothy, the isotopic compositions for calcite cluster around 12.2‰ d18O and -3.7‰ d13C. It probably resulted from a mixing processes between marine sourced carbon-oxygen (ca 20‰ d18O and -0.5‰ d13C) and other distinct geochemical reservoirs, eg magmatic C-O. These features indicate that Phase 2 skarn and Cu-Au (REE-U) mineralisation may be related to unexposed intrusions at deeper levels.CITATION:Sha, P, Spandler, C and Chang, Z, 2015. Elaine Dorothy Cu-Au (REE-U) skarn deposit, in Proceedings PACRIM 2015 Congress, pp 445–450 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By I Canbulat, J Emery, L Yao and C Zhang

This paper documents a process of data analytics and machine learning applied to coalmine roof convergence data. It follows a publication documenting the formation of the database. For each set of analyses Python scripts were utilised to extract data from an SQL database, with subsequent analyses also executed in Python, utilising open-source tools such as scikit-learn. Preliminary analyses with classic machine learning algorithms included multiple logistic regression, K-nearest neighbours, decision tree, random forest, support vector machine, kernel support vector machine, artificial neural network (ANN), naïve Bayes and multiple linear regression. Results indicated that relationships were complex and non-linear, with the artificial neural network most suitable. An ANN model was then refined through a standard process of hyperparameter optimisation and data augmentation to arrive at a final model. Due to the black box nature of the ANN further insight into how the parameters interacted was sought and found with Shapley additive explanations (SHAP values). SHAP values utilise Game Theory, where each input parameter or feature is a ‘player’ while the data set is the ‘team’. The SHAP value is the impact of each player on the target value, essentially establishing the contribution of each input parameter. The results from all analyses are delivered in the paper, together with insights, applications, strengths, and limitations of the methodology.

Nov 29, 2022

Carbonatites - igneous carbonate-silicate rocks - host the world's major resources for niobium, phosphorous and REE (rare earth elements).Carbonatites represent the least common products of mantle and igneous processes and their emplacement is principally controlled by lithospheric domes and rift structures. Intrusive carbonatites frequently comprise carbonate-amphibole-apatite-pyrocWore assemblages, occur as plugs, cores, dykes, sills sheets, veins, pipes and irregular bodies, are gecichemically anomalous (Ba, Ca, Cl, F, Hf, Mg, Nb, P, REE, S, Sc, SO4, Sri Tb, Ti, D, V, Zr), are associated with alkaline silica-undersaturated igneous rocks forming carbonatite complexes, and display large, intensive alteration haloes. Also carbonatites are similar to limestones, prone to weathering, and may form thick laterite profiles.Magmatic ores (pyrocWore, apatite, bastnaesite, monazite, magnetite, baddeleyite, phlogopite, fluorite, calcite) and weathering related residual and supergene ores (pyrochlore, apatite, magnetite, anatase, vermiculite) are currently being mined on all continents except Australia. Australia is underexplored for carbonatite associated primary magmatic and especially residual-supergene ore deposits. Chances are very high for the finding of new carbonatite, occurrences and associated ores.

Jan 1, 1994

By S Kakara, A Kamaraj, S S. Varanasi, B V. R Mandalika, M B. Shaik

The properties of top slags play a very important role in secondary steelmaking. Fluxes should be chosen based on the ladle furnace (LF) slag requirements like viscosity, melting temperature, sulfide capacity, etc. CaF2 and CaO-Al2O3-based synthetic slags are the most used fluxes in secondary steelmaking to improve slag fluidity and interfacial chemical reactions. CaF2 is obsolete due to fluorine pollution and CaO-Al2O3 based slags have 40–50 wt per cent Al2O3 and 30–40 per cent CaO which is not beneficial for desulfurisation. Yet another drawback is that LF slag disintegrates into fine powder during cooling due to phase transformation C2S (2CaO.SiO2). Hence, there is a need for the development of low melting fluxes with high CaO content and the capability to prevent slag disintegration. The current work studied the effect of 0–9 wt per cent B2O3 on physico-chemical properties and characterisation of LF slags. X-ray diffraction (XRD) analyses were carried out to identify mineralogical phases present in slag and Fourier-transform infrared spectroscopy (FT-IR) analysis was done to understand the changes in bonds of B2O3 added LF slag. The characteristic temperature of slag was determined by a hemispherical method using high-temperature microscopy. Empirical models were used to calculate viscosity, break temperature, and sulfide capacity. FactSage™, ver 8.2 (by GTT-Technologies) simulations were carried out to find the equilibrium phase fractions and percentage of liquid slag at different temperatures. New phases such as Ca11B2Si4O22 and Ca2B3O5 were formed in LF slag with B2O3 addition. Based on the results, 0.5–1.0 wt per cent B2O3 was found to be sufficient to prevent C2S-driven disintegration of LF slag. Also, the melting temperature and viscosity of LF slag were reduced by adding 3–8 wt per cent B2O3 due to the formation of BO3 planar triangular structure and low melting eutectics in slag. Liquid slag started forming at a temperature as low as 800°C when B2O3 is >6 wt per cent. It was found that the sulfide capacity, viscosity, and break temperature of the slag decreased with increasing wt per cent B2O3. Based on the analysis carried out, B2O3 can be a promising fluxing material in secondary steelmaking, for improving the desulfurisation kinetics and valourisation potential of LF slag.

Aug 21, 2024

By D Readett

The most critical variable in the successful establishment of the Murrin Murrin Heap Leach plant was the effective agglomeration of the Ni laterite ore. This paper describes the test work undertaken to establish the key agglomeration parameters including state of the art testing and analysis procedures. These parameters were then utilised to establish the key design and operational concepts for the world’s first commercial scale Ni laterite heap leach. Following the technical and economic success of the operation, the actual operational data is compared back to the original test work data.

Aug 8, 2011

By S Kowalczuk, S V. L Barrett

The potential for adverse surface settlement during tunnelling in soil and rock poses a significant risk to the successful completion of any tunnelling project. Undesirable ground movement may lead to unacceptable level of damage to surface infrastructure, buildings and the environment, resulting in safety concerns as well as causing significant delays and costs to a project. One of the empirical methods which is commonly used to predict surface settlement in the early stages of a project’s development is the volume loss approach as described by Mair, Taylor and Burland, 1996. This method was developed for use in soft ground; however it has also been applied in weathered and soft rock to provide an initial indication of potential surface settlements along a proposed tunnel alignment. This paper presents some initial thoughts on the use of this method in weathered and soft rock and the associated limitations which need to be taken into consideration when interpreting the results. This includes complex weathering profile cases where the strength and stiffness of the ground does not necessarily increase with depth.CITATION:Kowalczuk, S and Barrett, S V L, 2014. Initial thoughts on application of the volume loss approach for estimates of surface settlement due to tunnelling in weathered rock, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 641–646 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By N Stockton

Some preliminary results on the secondary leaching of previously heap leached gold ore are presented. Alternative lixiviants for gold comprising chlorine, thiourea and thiosulphate were compared with cyanide using bottle roll tests. Chlorine was subsequently selected for column leaching tests. Column tests at 1.0, 0.1 and 0.01 gL-1 Cl2 at pH 2 were conducted. The results indicated that about 23 per cent of the gold was leached over 45 days using 1 gL-1 Cl2 at pH 2. The experiments conducted proved that the chlorine/chloride system has good potential for further extraction of gold and silver from the existing cyanide heap leach residues and a process for secondary leaching of gold has been proposed. Further testwork is recommended to extend conditions, sample types, and the duration of leaching period.

Jan 1, 2000

The Kiirunavaara apatite-magnetite orebody is about 4 km long and approximately 100 m thick sheet-like body, which lies roughly in a north-south direction and dips from the horizontal plane along its entire length, in towards the town of Kiruna. The origin of this orebody has been a matter of controversy, with both magmatic and hydrothermal origins proposed. Traditionally and for practical purposes this rich apatite-magnetite ore has been divided into two main types: low phosphorous ore (B-ore) and high phosphorous ore (D-ore). Further the low phosphorous ore is divided into the low alkali (B1) and the high alkali (B2) ore.

Jan 1, 2006

Land is of extreme importance to citizens of Papua New Guinea and is fundamental to most of their customs and values. Because of this, matters to do with land cannot easily be separated from other matters to do with the community. Good relation-ships with landowners and the community surrounding a development are, indispensable ingredients that -must flavour and colour the entire ;operati on .

Jan 1, 1994

By R Forster

Direct ship iron ore (DSO) operations at Extension Hill in Western Australia’s Midwest region have commenced, with fi rst product railed to the port of Geraldton in July 2011. Reserves are 14.8 million tonnes (Mt) of haematite-goethite ore overlying an Archaean BIF-hosted larger magnetite deposit which Mount Gibson Iron Limited (MGI) sold to other parties in 2006.Some unique geological aspects of the deposit shape DSO mining and processing operations. Owner-operator selective mining, blending, crushing and screening on site will produce three million tonnes per year (Mt/a) of Lump and Fines product to be trucked 86 km to Perenjori, railed 232 km to Geraldton, and loaded aboard Panamax-sized ships through the dedicated iron ore shiploader at the Geraldton Port Authority’s Berth 5 facility.The statutory approvals process for this project formally began in 2004, dominating delays in a predevelopment phase which extended over a longer period than the likely life of DSO operations. The lack of transparency, uncertainties and costs inherent in state government processes have influenced decisions made by MGI while assessing other development opportunities in Western Australia. Potential for additional Reserves exists at Extension Hill, however MGI’s ability to extend the mine life will hinge on statutory approval to explore for and evaluate other DSO resources on surrounding granted mining leases.The nature of the resource and use of existing infrastructure for product transport have enabled MGI to keep operating costs and capital intensity of this project relatively low. A tenacious development approach by MGI and robust project economics have fi nally enabled this site to take its place as a revenue earner beside the company’s other DSO operations at Tallering Peak and Koolan Island.

Jul 11, 2011

By J Simpson, M Johnston

Recently Mount Isa Mines undertook a study to review the lead-zinc orebodies to extent of resource and reserves and determine the new life-of-mine schedule, as the Mount Isa and Hilton orebodies had not be reviewed for many years. Also, the recovered value of the Mount Isa, Hilton and George Fisher orebodies had been increased by major performance improvements in the lead-zinc concentrator. The Mount Isa Lead-Zinc concentrator processes fine-grained lead-zinc ore from the Mount Isa, Hilton and George Fisher orebodies. These orebodies have varying levels of pyrite and large variation in the grain size and texture of the galena, sphalerite and pyrite. This variation has a large effect on the recovery of the lead and zinc in the concentrator. Some ores achieve 90 per cent recovery at target grades, yet other ores are unable to achieve æsaleableÆ concentrate grade, with no metal being recovered to concentrate and therefore effectively losing the contained metal to the final tailings. Models were created to predict the metallurgical performance of these orebodies, to better reflect the variation that occurs. These improved metallurgical models and economic data allowed the determination of the Net Smelter Return (NSR) for each block in the geological block model. This NSR is the return to MIM of the metals contained in concentrate. The NSR was used as the cut-off grade criteria when determining the value of the ore. This formed the basis of the lead-zinc life-of-mine schedule and the optimisation of the lead-zinc business.

Jan 1, 2003

By P Luo, J E. Danoczi, P Nakutnyy

Sensor-based sorting methods to remove waste or for upgrading ore prior to downstream metallurgical processing is becoming more prevalent for mining operations. X-ray transmission (XRT) sorters are a popular choice for mineral processing plants since they can sort a wide variety of minerals. XRT sorters pass high intensity X-rays through particles to generate images of varying greyscale, based on their effective atomic density. The ore sorter then mechanically separates the particles using algorithms based on the images. A popular test currently used to evaluate the amenability of the ore to XRT sorting is to pass the particles through the sorter and obtain the greyscale images showing mineralogical differences. This test provides information on the mineralogical heterogeneity between ore particles for their separation. However, it does not provide an understanding of the actual mineralogical composition of the ore or information pertaining to which other minerals may respond in a similar manner, nor does it provide liberation information. This paper describes a test that combines high resolution X-ray micro Computer Tomography (CT) combined with QEMScan to obtain information about amenability of ore to XRT sorting and to obtain valuable information that can streamline metallurgical testwork programs. This test also provides information relating to particle thickness and associated X-ray attenuation coefficients, desired mineral presence and mineralogical information relating to associated minerals and clays to assist with developing sorting algorithms. Combining the CT and QEMScan can address many limitations of the current method to determine whether XRT sorting technology is appropriate for particular ores. Mineralogy information from QEMScan can identify incidences of; mineral encapsulation, problematic clays, detrimental minerals as well as calibrate the greyscale values of CT data. Additional 3D CT imaging carried out on cores provides spatial information of the minerals within the ore and mineral grades.

Nov 10, 2020

The phosphatic overburden of Christmas Island is a lateritic soil and consists dominantly of crandallite and millisite. These minerals are polymorphs of general formula, (Na,K)x Ca2-x (Al, Fe)6 (PO4)4 (OH)10-x (2+x) H2O. Iron occurs only in millisite. Both minerals exhibit similar thermal transformations, dehydroxylating near 600¦C and recrystallizing above 800¦C. Dehydroxylation results in crystal structure collapse but retention of crystal morphology. Ggethite, boehmite and apatite are minor constituents of some-of the phosphatic Soils.

Jan 1, 1971

By G J. Lyman

The theory of sampling has progressed slowly over the last century. The concepts of correct sampling were known to mining engineers such as D W Brunton in the 19th century. It was recognised early in the 20th century that the Poisson distribution of particles carrying the target analyte was the key to the uncertainties between samples of a given mass. However, no efforts were made until the 1980s to determine the entire sampling distribution as a function of sample mass. The variance of sampling was made clear by Gy and others, but none attempted to determine the entire sample assay density function until J H Venter in South Africa applied the method of characteristic functions to the problem.Venter applied the method to a specific case of very low analyte concentrations in samples of very fine particle size where his assumption of constant sample mass was justified. When his general methodology is applied to the more general problem, it can be shown that the assumption of constant sample mass is no longer justified and leads to some anomalous results for sampling variance. Venter’s method can be expanded to allow for a statistically variable sample mass and to take into account the size distribution of particles that carry no analyte.This paper presents the basis of Venter’s work and shows how the approach can be easily modified to yield results for the variance that are consistent, for example, with the work of Gy. It is also demonstrated that the entire sampling distribution can be determined without undue computational burden when sufficient information on the material heterogeneity has been collected.CITATION:Lyman, G J, 2014. Determination of the complete sampling distribution for a particulate material, in Proceedings Sampling 2014 , pp 17–24 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By D Newton

The Mt Morgan Minesite in Central Queensland has been subject to both underground and surface gold mining operations since the late-1800s. The site is largely unrehabilitated and poor quality surface run-off and subsurface leachate is contaminating the nearby Dee River. The site is dominated by a large open cut, which now stores contaminated surface and subsurface run-off. Three models were used to simulate the complex hydrologic processes occurring at the Mt Morgan Mine: a rainfall-run-off model, a groundwater model and a storage behavioural model. Study results showed that the open cut is filling with water and will soon spill large volumes of highly polluted water to the Dee River on a regular basis if no remedial action is taken. This will result in a three-fold increase in pollutant load to the Dee River. Based on a consideration of water quality and quantity it was concluded that the first priority for future minesite water management should be the prevention of spills from the open cut. Potential management options to achieve this objective included surface rehabilitation, catchment diversions, modification of the pump-back system and controlled releases to the Dee River during floods. However, assessing the relative effectiveness of these measures required a thorough understanding of the complex surface and subsurface hydrology of the site. The results of a 100 year simulation of hydrologic processes revealed that previously favoured management options would be ineffective in preventing spills to the river. On this basis, a continuous treat and release strategy was proposed as the only reliable method of preventing future spills. The results of this study demonstrate that good environmental management decisions must be based on an understanding of the relevant physical processes and consideration of cumulative effects over an appropriate time scale.

Jan 1, 2003

By A L. de Ambrosis, S J. Clarke, R Bertuzzi, J Redelinghuys

The M2 Upgrade Project involved widening 15 km of the existing M2 Motorway, which is a key route in Sydney’s road network. The Norfolk Twin Tunnels in North Epping convey traffic over a 460 m length of the motorway. The project involved widening the twin tunnels to provide a third lane and breakdown lane in each direction.The widening of the tunnels was fundamentally different to other ‘greenfield’ tunnel projects in that the operation of the tunnel was maintained throughout construction, with motorway traffic permitted close to the excavation faces on a daily basis. The widened works had to integrate with the existing tunnel support, construction details, and mechanical and electrical infrastructure.The existing tunnel afforded the opportunity to review existing ground conditions in the tunnel. Exposures were mapped within the tunnel, and key design parameters were back-analysed from the original monitoring data to provide increased confidence in the assessed impact from the widening works.Traffic capacity of the tunnels was maintained by detailed staging of the works, and included the ability to reopen the tunnels at short notice.A permit to tunnel system was developed to manage the risks associated with re-opening the tunnel to traffic. A comprehensive suite of instrumentation was maintained to provide reliable monitoring data to support this process. Emphasis on the robustness and reliability of tunnel instrumentation provided increased confidence in the adequacy of the tunnel support being installed. The monitoring was routinely compared with design predictions to check the adequacy of the support measures being installed and confirm the design.The approaches and methodologies developed for the widening of the Norfolk Tunnels were effective in maintaining the safe operation of the tunnels throughout the two years of construction, and provide a framework for increasing the capacity of existing tunnel infrastructure in the future.CITATION:Clarke, S J, de Ambrosis, A L, Bertuzzi, R and Redelinghuys, J, 2014. Design and construction for the widening of the M2 Norfolk Twin Tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 591–602 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M G. Millad, M Zammit

The Kipoi Central (KPC) copper project is located in the Katanga Province in the Democratic Republic of the Congo and is presented here as an example of an operating mine where the Mineral Resource was initially estimated by uniform conditioning (UC) and subsequently updated to localised uniform conditioning (LUC). This paper discusses the implementation of an estimate run using LUC and compares the results based on resource definition drilling to those obtained by close spaced grade control drilling and actual mill production.UC is a nonlinear geostatistical technique designed for recoverable resource estimation, typically using wide spaced exploration and resource definition drilling. The primary output of UC is the grade, tonnage and metal above a series of user-defined cut-off grades for a particular selective mining unit (SMU) block size. The UC approach is considered to provide a more accurate representation of the recoverable grade and tonnage at SMU support for non-zero grade cut-offs than would typically be achieved by a traditional linear estimator such as Ordinary Kriging. LUC is a relatively new approach involving the post-processing of a UC estimate and is used to spatially present the grade distribution predicted by UC at the SMU scale.This study demonstrates that the calculation of a more accurate and realistic grade-tonnage relationship for small SMU sized blocks is possible at the exploration stage using LUC, provided that the necessary theoretical and practical conditions for implementation of this technique exist.CITATION:Millad, M G and Zammit, M, 2014. Implementation of localised uniform conditioning for recoverable resource estimation at the Kipoi Copper Project, Democratic Republic of the Congo, in Proceedings Ninth International Mining Geology Conference 2014 , pp 207–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014