Search Documents

By C E. J de Ronde, J L. Mauk

Sulfide chimney samples collected during the 1998 - 1999 R/V Atlantis û DSV Alvin 3 - 30 research cruise have been examined and classified into four types, based on common characteristics. Chimney morphology is the most important characteristic and resulted in the following groups: 1. flutes, 2. cones, 3. wide-flats, and 4. beehives. Other characteristics resulted in the classification of subgroups within the flute, cone and wide-flat groups. The combination of characteristics, including; the presence of an orifice, internal chimney fabrics, wall thickness, extent of weathering, and the presence of Alvinella worm casts, enable evolutionary trends between the different chimneys types to be established. These trends indicate that with time, flutes evolve from immature zoned chimneys with a central orifice and smooth thin-walls, into cone chimneys with thick walls and massive fabrics which have their orifices infilled by massive sulfides, and a rough exterior. Repeated mineralisation within, cones may result in the formation of wide-flat chimneys. Beehive chimneys can form at any time during chimney growth.

Jan 1, 2003

The Round Hill gold-scheelite deposit is located three kilometres from Macraes Flat and approximately 60 kilometres due north of Dunedin, New Zealand. A mining feasibility study is currently being undertaken on the deposit by BHP Minerals (New Zealand) Limited, who are the managers and operators of a Joint Venture with Home Reef Mining Limited. BHP has a 70 per cent equity in the project area.

Jan 1, 1987

By D P. Telionis, P P. Vlachos, R-H Yoon

Industrial processes involving multi-phase flows such as flotation require understanding of the relationships between bubbles, solid particles and the flow. Modern experimental tools are employed in this effort to measure with great accuracy the basic features of the motion of all three phases in turbulent flow. We employed a unique digital particle image velocimeter (DPIV) that can record with great accuracy and kHz temporal resolution, velocity vectors of all three phases, namely the fluid, the solid particles and the air bubbles. The interaction of these three phases was studied in homogeneous isotropic turbulence generated by cylindrical grids. Particles and bubbles were released into the turbulence and the motions of the three phases were monitored. The experimental results obtained in the present work were compared with the predictions of the models published in the literature.

Jan 1, 2005

By H Ramandi, H Masoumi, I Canbulat, B Hebblewhite, J Oh, S Saydam, W Timms, S Mo

This paper reviews the floor heave mechanisms in underground coal mine roadways. Previous studies have reported three main failure mechanisms: bearing capacity failure, buckling and swelling. The buckling failure has been observed where immediate floor strata are relatively strong and thinly bedded. On the contrary, the weak floor strata have been associated with both the bearing capacity failure and swelling mechanisms. The bearing capacity floor failures are likely to induce other types of instability such as pillar punching, tensile failure of pillar, roof fall and subsidence as well as floor heave. Despite a considerable amount of research, predicting the magnitude, location and timing of floor deformation is challenging with current state of knowledge. CITATION:Mo, S, Ramandi, H, Oh, J, Masoumi, H, Timms, W, Canbulat, I, Hebblewhite, B and Saydam, S, 2018. A review of floor heave mechanisms in underground coal mine roadways, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 196–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By R J. Norris, D J. MacKenzie

Gold-bearing veins have formed at a wide range of depths throughout the uplift history of the Otago Schist. The earliest gold mineralisation occurred during the later stages of Mesozoic metamorphism. This mineralisation was characterised by diffuse wall rock alteration with greenschist facies metamorphic or retrograde metamorphic mineral assemblages, and gold occurs in this altered rock. Quartz veins formed in .steeply dipping extensional fractures associated with this mineralisation type strike north to northeast. The Macraes mine exploits this deposit type. The present northwest strike of the mineralised zone at Macraes is a result of post-mineralisation deformation of the schistosity-parallel mineralised shear zone which hosts northeast striking extensional veins. This combination of schistosity-parallel shear zone and steeply dipping northeast striking veins may exist elsewhere in Otago, and this deposit type is most prospective. Steeply dipping quartz veins formed during post-metamorphic un-roofing of the Otago Schist strike northwest to west and occur as clusters of near-parallel structures in east and central Otago. These veins consist mainly of massive quartz, although some prismatic quartz occurs also. Breccia fragments in veins are common and these are generally silicified, with some gold. Wall rock alteration is negligible, and vein margins are sharp. A set of middle Tertiary veins occurs in northwest Otago. Most of these also strike northwest and dip steeply, but some strike northeast. These veins contain abundant ankeritic carbonate as well as quartz. The carbonate pervades adjacent wall rock as veinlets, but gold mineralisation is confined to veins. Quartz is commonly prismatic and vuggy, and contains gold, which is commonly coarse grained especially in silicified breccia zones. Associated veins contain stibnite. This vein type formed close to the paleosurface (>2 km). Mineralised veins in Marlborough currently strike northwest, but these have been rotated from northeast strike during Alpine Fault displacement of Marlborough from Otago. Some of these veins were formed under late metamorphic conditions and are similar to the north to northeast striking veins in Otago. As in Otago, this type should be considered to be most prospective if they have associated schistosity-parallel shears.

Jan 1, 2000

By R H. Yoon, M Gupta, A Noble, K Huang

Froth flotation is the most commonly used separation technology in the mineral industries. Given the complexity of the pulp and froth phases as well as the multitude of operational parameters that influence flotation performance, purely fundamental models with strong predictive capacity are limited. As a result, accurately modelling modifications to an existing flotation circuit are challenging, particularly when using empirically-derived models from a different operating configuration. Despite these complexities, a recent publication by the authors (Huang et al, 2022) has shown that flotation rates can be accurately predicted from a first-principles model that incorporates hydrodynamic parameters (eg pulp density, superficial gas velocity, feed flow rates etc), surface chemistry parameters (eg contact angle, zeta potentials and surface tension), and size-by-class liberation data. Circuit simulations using this model were shown to be effective in predicting experimental graderecovery curves from the size-by-class mineral liberation matrix. Since the model is derived from fundamental characteristics of the flotation system, it can be used to simulate alternative circuit configurations with varying degrees of recycle. Conventional flotation circuits are operated in a closed-circuit configuration by routing the cleaner scavenger tails (CST) back to the rougher feed to provide an additional opportunity to recover the slow-floating particles. This widely-used flotation strategy has been under constant debate, and several researchers have provided evidence that open circuit configurations provide higher separation and better circuit control (Konigsman, 1985; Bulatovic et al, 1998; Thompson, 2016). Recently, Finch and Tan (2021), used linear circuit analysis to show that open circuit configurations have a fundamental advantage when stage recoveries are high. Given the limitations of these prior studies, the objective of the current work is to further evaluate the merits of the open circuit configuration through a detailed circuit analysis and simulation study incorporating the first principles model described above.

Aug 24, 2022

Recovery of Fine Gold Particles from Philippine Gold Deposits by Enhanced Gravity Concentration and Flotation The objective of the study is to determine the applicability of enhanced gravity concentration (EGC) and flotation for gold recovery. While gravity concentration methods have long been applied to gold ores, especially to free-milling types that requires minimal beneficiation, flotation for gold recovery has not yet taken hold as a major operation in the Philippine setting. In this study, the application of EGC and flotation for gold is applied and compared to the existing methods for gold recovery. Two samples, with assays of 7.315 and 5.333 g Au/MT (samples 1 and 2, respectively) are used for this study. These samples are subjected to mineralogical studies and is found to have a gold-particle size ranging 10 to 200 microns. To verify the separation size, the mesh-of-grind (MOG) is used as the primary parameter for experimentation. Initially, the samples are stage-crushed, ground, and subjected to EGC using a Falcon SB40 Concentrator. Based on the results, the two samples showed that recovery increases with a finer MOG. The ratio of concentration (K) decreases with a finer MOG. This shows that there should be sufficient liberation of the gold values for EGC to be effective. The effect of the enhancement is to pronounce the difference in specific gravity of the minerals, promoting better separation. This is validated by the high recovery values of 86.97 per cent and 98.73 per cent exhibited respectively for samples 1 and 2 (at 54 microns). For the flotation runs, sample 2 with an average particle size of 80 per cent passing 74 microns is examined using thiocarbamate-based collectors for roughing and subsequently exhibited a recovery of 96.32 per cent. At this point, the concentration ratio (K) is noted as an important efficiency indicator for flotation process since it yielded a very low-mass and high-metal content concentrate.

Sep 13, 2010

By G K. N Subasinghe

"In the design and operation of mineral processing plants, knowledge of the variability of ore properties and that of the expected metallurgical performance within the orebody is of great importance in order to avoid both production constraints due to inadequate design and less than expected metallurgical performance during operation. Of the many properties that determine the performance of downstream separation processes, such as flotation, gravity separation and leaching etc the liberation characteristics are of primary importance.Current methods of evaluating liberation characteristics of ores such as the use of Mineral Liberation Analyzer (MLA) and QEMSCAN techniques are expensive and suffer from the drawback that these tests are performed on comminuted particles at a given grind size and/or samples of product streams. This problem could be overcome by developing predictive models of liberation that can predict the grade distribution of comminuted products at any grind size based on texture of the parent rock. This paper discusses a procedure that has been developed to predict liberation using information obtained from a sample of the parent rock such as drill core, based on Barbery’s liberation models. The required characteristic statistical functions have been evaluated from image analysis techniques using scanning electron microscope (SEM) images of the parent rock and narrowly sized comminuted particles. Such information can then be used in a predictive model to predict or explain the variability of metallurgical performance at various grind sizes used in future operating plants. The model will predict not only the valuable mineral liberation but also gangue liberation, which will be useful to those who are looking to remove liberated gangue from comminution circuits.CITATION:Subasinghe, G K N, and Dunne, R, 2016. Predictive Model of Mineral Liberation for Geometallurgical Applications, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 347–350 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

The Archean Gossan Hill Group at Golden Grove, Western Australia, hosts two potentially economic volcanogenic massive sulphide deposits. The volcanic-sedimentary succession hosting this mineralisation is composed of a facies association which includes the products of rhyodacitic to,andesitic effusive volcanism, mass-flow sedimentation and concentrated hydrothermal fluid discharge, in a deep subaqueous setting. The Tertiary Kuroko deposits of Japan are widely compared to Archean volcanogenic massive sulphide deposits and a comparison of the facies associations hosting this style of mineralisation, in these two successions separated widely in time, allows a refinement of facies models suitable for exploration in ancient successions. The required deep subaqueous environment for the formation of volcanogenic massive sulphide deposits places constraints on the physical processes that can operate during accumulation of the host stratigraphy. Limitations on the operation of physical processes is reflected by the resultant facies association which can be used to characterize suitable volcanic-sedimentary successions in which volcanogenic massive sulphide mineralisation may be present. The facies association includes: (1) proximal effusive volcanic products - lavas and associated autoclastic breccias (2) distal volcanic products - mass-flow resedimented pyroclastic debris (3) background sedimentation - reworked volcanogenic and terrigenous mass-flow sediments and (4) chemical sediments - exhalites including cherts, sulphides and oxides, with perhaps various carbonates and sulphates. Primary pyroclastic deposits are not expected to be present, other than distal water-lain air-fall deposits, derived from shallow to emergent basin margin explosive volcanic centres, which also provide a source for the resedimented pyroclastic debris.

Jan 1, 1987

By R G. Barker

The NZ Minerals Industry Association has continued to advance the interests of the minerals sector through leading the establishment of a Minerals Industry Advisory Committee, and the preparation of a technology strategy with funding assistance from the Foundation for Research, Science and Technology. The current moves mirror those of more than 30 years ago when a government initiative led to a resurgence of exploration through amending the mining legislation, redirecting Government research priorities and tax changes. The economic and political and commercial environment in 2001 is very different from that of the 1960s and success of these new initiatives depends on the continuing support and involvement of all sectors of the minerals industry, and building an improved relationship with the Government and the public.

Jan 1, 2001

By J Wheeler

The benefits of fine size separation in magnetite concentration are detailed focusing on published research from various iron ore producers. Basic principles of fine sizing and advancements in screening technology are addressed. A chronological review of research is used to show the evolution of fine sizing applications in the industry, starting with studies that demonstrated the benefit of using fine screens to produce consistent lower silica concentrates, followed by improvements in fine sizing equipment that have made effi cient screen classification in ball mill circuits practical. Case studies are used to demonstrate how positive sizing with screens can be used to significantly shift concentrate ‘grind/grade’ relationships.

Jul 11, 2011

By Zeni J. T

Gold was mined from quartz bodies at Ballarat East from the 1850s until closure of the last mine in 1917. The average depth of mines was about 350 m.Ballarat Goldfields Limited (BGL) carried out diamond drilling from surface between 1985 and 1987 which proved the continuation of gold-quartz mineralisation beneath the old mines.During 1989 an underground development program was commenced to access the mineralisation for detailed exploration. The program included two simultaneous shaft developments. These were known as B2 shaft and Llanberris No.1 shaft.

Jan 1, 1992

By J J. Boshoff

This iron ore mine site, located in the Pilbara region of Western Australia, commenced operations in 1998, with ore derived by mining of open-cut pits in Channel Iron Deposits (CIDs). A portion of the ore extracted at the mine is processed at wet processing plants that produce both ore saleable product and waste fines (i.e. tailings) slurry. The waste fines produced at the wet plants are presently stored within Waste Fines Cells (WFCs).Waste fines cells A (WFCA) and B (WFCB) are located within an Autonomous Haul System (AHS) area and consist of embankments that span the width of the pit in east-west alignments. Technical studies and design analyses were carried out to support embankment raises and ongoing development of the WFCs. During operation and development of the WFCs, a multitude of simultaneous activities took place to the immediate north and south of WFCA respectively. These activities included the construction of the embankment raises using the AHS fleet, mining of the CID to not only mine the ore but to also create future deposition space for WFCB, blasting next to the WFC embankments as part of the mining activities, seepage collection and dewatering of the pit in the vicinity of the WFC.This paper discusses the material characteristics, design approach, construction staging and equipment requirements, blasting near embankments, water management, facility consequence category and closure concept.CITATION:Boshoff, J J, 2018. A waste fines cell with a multitude of concurrent activities, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 39–49 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By M Yahyaei, F Reyes, R Lage, V Jokovic

Equipment wear is strongly related to the performance of grinding circuits. In particular, SAG mills are subjected to the wear of their shell liners and grates. Changes in lifter height and face angle impact mill performance, while classification at the mill discharge is also affected as grates wear out. Moreover, liner mass loss caused by wear affects how operators interpret readings of sensors such as load cells or bearings pressure. Automating and optimising grinding circuits under these constrain becomes challenging due to the nonlinear and dynamic nature of the system. The operation of SAG mill grinding circuits remains largely dependent on human intervention, which frequently results in inconsistencies in performance across shifts, reflecting the operator’s personal preferences, experience, and other human factors. The influence of human factors can be reduced by careful training of operators as well as by automation using advanced supervisory control. The latter approaches could benefit from the development of dynamic process models that consider the effects of wear on the performance of equipment over time. This paper presents detailed industrial data showing the effects of wear on SAG mill performance. Additionally, a dynamic SAG mill model that accounts for these phenomena is proposed and demonstrated in a simulated environment. This model is shown to mimic the effect of wear on the performance of industrial scale mills and the operational constraints they are subject to, thus extending traditional SAG mill models. Incorporating wear into modelling and simulation platforms can improve the understanding of the effects that wear can have on the performance of key assets in comminution circuits and may allow the development of more robust model-based advanced process control strategies.

Aug 24, 2022

By D Bradshaw, E Forbes, M Edraki, M Tayebi-Khorami, E Manlapig

There is an increasing trend in the extraction and development of copper resources from complex deposits. These deposits pose mineral processing challenges, as they often contain low grade disseminated copper ore with high levels of impurities particularly arsenic. Although arsenic is a naturally occurring element, the concentrations of arsenic can be magnified by mining and mineral processing activities. Therefore, while arsenic has no significant market value, its presence in the ore deposit will have production, environmental and human health implications. The mining industry’s approach to life-of-mine planning has improved significantly in recent decades and managing arsenic is not an exception.CITATION:Tayebi-Khorami, M, Edraki, M, Manlapig, E, Forbes, E and Bradshaw, D, 2018. Arsenic pathways in copper mining – sustainability issues and potential solutions, in Proceedings Life-of-Mine 2018, pp 60–63 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By K Banerjee, C Dube

Veolia Water Technologies was contracted by a global coal mining company to design a retrofit acid mine drainage treatment facility using DenseSludge™ technology on a former coal refuse disposal site. The project constraint was to reuse current facilities in order to reduce additional capital work cost and avoid additional footprint requirements while improving treatment performance and reducing sludge production and chemical consumption. The initial installation of 454 m3/h served as a pilot plant to demonstrate the benefits of the process and ultimately provided design criteria for the new facility. The pilot demonstrated the benefit of the technology by reducing sludge volume by 90 per cent compared to conventional processes currently in use. The sludge that is reinjected into the mine contains less water, which reduces the volume of water that returns to the mine pool for treatment and mine water balance. Furthermore, the pilot plant reduced lime usage compared to conventional processes by operating at a lower pH set point, demonstrating steady pH control and stoichiometric lime utilisation.CITATION:Dube, C and Banerjee, K, 2015. Sludge conditioning technology to reduce sludge and the cost of acid mine drainage treatment, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 105–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By S M. Aminossadati, C M. Stewart, M S. Kizil

Mine ventilation models are now an accepted component of most mine management systems. However, modern ventilation models also represent a highly structured spatial data source, defining underground pathways and connections across a mine. This creates opportunities to extend the use of network models beyond ventilation design, by using critical path algorithms to find pathways such as minimum distance or minimum time.This paper explores the use of ventilation network models to automatically analyse and calculate potential emergency escape routes. A variation of Dijkstra’s algorithm is used to predict complex pathways between any two points across a model, representing an escape route from an emergency area (such as a fire) to a safe location (such as the surface or a refuge station). Weighting can be assigned to paths to represent potential travel speed, obstructions or preferred routes. Finally, emergency considerations such as smoke or gas in some parts of the mine can then be incorporated into the pathways to force the algorithm to avoid dangerous routes and specify safer pathways. Ventsim is used to visually show example results.Emergency egress pathway prediction using ventilation network models can provide an efficient way to quickly predict the quickest or most efficient escape routes for emergencies or planning purposes.CITATION:Stewart, C M, Aminossadati, S M and Kizil, M S, 2017. Emergency egress pathway prediction using ventilation models, in Proceedings Australian Mine Vent Conference 2017, pp 57–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Comalco's Bell Bay smelter produces some 94 000 t.p.a. of primary aluminium in the form of foundry alloys, extrusion billet and rolling blocks. The extrusion billet and rolling block are produced by a process, in which molten aluminium is poured into an open ended water cooled mould of the required shape. The bottom of the mould is initially closed off by a dummy or starting block. Primary cooling takes place at the mould wall and secondary cooling is achieved by direct water sprays onto the out side shell of the product. Careful preparation of the molten alumin- ium is essential if stringent alloy specific- ation limits are to be met. Optimum casting temperature must be maintained within a narrow range and metal cleanliness is important to ensure a consistent product. Increased demands of recent years for larger product and higher standards of surface quality and dimensional control have been instrumental in forcing improvements in furn- aces, casting machines and in mould and dummy Doq,

Jan 1, 1977

The Kyaukpahto gold deposit is located at latitude 23¦ 47Æ 55" N and longitude 95¦ 56Æ 35" E in the Kawlin-Wuntho district, Sagaing Division, Myanmar. Gold mineralisation is hosted in sandstone of the Male Formation (Eocene) and occurs as stockworks and disseminations. The high-grade gold mineralisation is locally concentrated in a breccia zone. The gold deposit is closely associated with a NNE-SSW trending fracture system that forms tensional open fractures. These tensional zones are thought to be directly related to the Sagiang transfer fault system that experienced several hundred kilometres of northward dextral movement during the post-Upper Miocene. Major sulfide minerals are pyrite and arsenopyrite with minor galena, chalcopyrite and sphalerite. Gold mineralisation is associated with intense silicification, sericitisation and argillic alteration. Primary Type I fluid inclusions in the quartz from the mineralised zone are 5 to 15 ¦m across and yield homogenisation temperatures of 239¦ - 310¦C and salinities of 1.2 - 10.9 wt per cent NaCl equivalent. Laser Raman spectroscopic analysis indicates the presence of CO2 and CH4 in Type II fluid inclusions. Sulfur isotope analysis of disseminated pyrite in the ore zone by the laser ablation method indicates d34S values from -5.48ë to +5.53ë. The geology, alteration, ore mineralogy, fluid inclusion microthermometry and sulfur isotope data of the Kyaukpahto deposit are consistent with an epithermal ore deposit model for the deposit. However, the presence of CO2-liquid bearing fluids and the detectable CH4 in the gaseous phase of the fluid inclusions conflict with a typical epithermal origin for the Kyaukpahto deposit. The host siltstone and mudstone sequence, trace element geochemistry, and the disseminated nature of sulfide and gold mineralisation are also common characteristics of a sedimentary rock-hosted gold deposit, and these features may indicate a Carlin-like affinity. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By D L. Richardson, B Tiedt, C D. Morgan

Following residentsÆ concerns that the ongoing operations of Collinsville Coal (CCP) mine may be resulting in the release of contaminants, including products of acid mine drainage (AMD), into downstream environments, the Queensland Environmental Protection Agency (QEPA) issued CCP with a Notice to Conduct or Commission an Environmental Evaluation at Three Mile Creek. A key objective of the Environmental Evaluation was to assess the extent and magnitude of impacts to aquatic communities and their habitats. A multidisciplinary investigation examined a suite of physical, chemical and biological indicators to meet this objective. The study also aimed to identify contaminants of concern and the location of potential pollutant sources. Potential indicators of AMD, including elevated dissolved solids concentrations and low pH, were evident within the mine lease. However, significant differences in concentration of these indicators upstream and downstream of the confluence with Three Mile Creek were not observed. Although only proxy indicators of AMD contamination, these results suggest that the extent of impacts downstream is minimal. For the purpose of this study, physio-chemical indicators were selected on the basis of those best likely to provide an understanding of the likelihood of contamination, within the constraints of readily available long-term monitoring data. Ecosystem health indicators were adopted to supplement the existing data set and provide a more æroundedÆ perspective of water quality attributes within the system, generally unattainable by standard physio-chemical assessments. In contrast to AMD products, sediments were considered more likely to have a widespread impact on aquatic ecosystems. Waterways throughout the study region, including those unaffected by mining, have been affected by broad-scale sedimentation and were typically highly turbid. Due to the many diffuse sources of sediment potentially liberated within the catchment, the contribution of the mine compared to other land uses on total sediment loads entering streams is difficult to determine. This is clearly a major management issue for mines throughout the Bowen Basin. Streams of the central Queensland region display enormous variability in water flows and physio-chemical characteristics over a range of spatial and temporal scales. This variability presents major difficulties in distinguishing anthropogenic impacts from natural variability (noise). Despite this variability, impact monitoring by mines in the central Queensland district has tended to focus almost entirely upon physio-chemical indicators. The results of the present study indicate that a multiple indicator approach to environmental assessment is more useful for separating mine related impacts from natural ænoiseÆ and impacts from other land uses. In the absence of such information, by adopting the precautionary principle of Ecologically Sustainable Development (ESD), there is potential for an environmental impact to be incorrectly attributed to mining when other activities in the catchment may be contributing to changes in stream æhealthÆ.

Jan 1, 2003