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Teleseismic travel time residuals measured on 600-1000 km seismic arrays across the Rio Grande and East African rifts provide evidence for upper mantle low velocity zones beneath each rift of velocity contrast 6%-8%. Refraction studies show thinning of the crust below the rift axes. Regional uplift which extends hundreds of km either side of the axes, is isostatically compensated by negative density contrast at depth. Since the refraction argues against compensation by thickened crust, compensation in the upper mantle low velocity zones is suggested. Temperature effects alone can not explain the reduced velocities. Generation of a few percent of partial melt is the most probable source of the reduction. A passive extensional mechanism is investigated for the Rio Grande rift in which hot asthenosphere intrudes the lithosphere raising its temperature and generating moderate melting. It requires less than 1% extension to explain the melting but a prodigious 26% to raise the temperature from a pre-rifting continental geotherm to the solidus. Geological estimates find that extension is less than 10% over the uplift zone. Such a mechanism is possible only if the prerifting lower lithosphere geotherm lies closer to the solidus than that of stable continent. This is supported by the observed high heat flow in the Rio Grande rift uplift region which, given the long time constant for thermal diffusion, reflects elevated temperatures at depth well in advance of the onset of rifting.

Jan 1, 1987

This paper covers only the energy uses of natural resources and does not deal with non- energy uses, which in 1975 were of the order of 10 per cent of the total consumption of energy resources. The United Nations `J' Series of Statistics ex- presses each of the various forms of energy in terms of its coal equivalent in metric tonnes and this basis is followed in this paper. One tonne of black coal (referred to as tce) has been taken as the equivalent of the following. 29 X 109 joules or 27.5 X 106 Btu 0.68 tonnes or 4.8 barrels of crude oil 750 cubic metres or 26.5 X 103 cubic feet of natural gas 1 ò5 to 3.3 tonnes of peat or lignite (world average 2.54; Victorian brown coal 3 0) 8055 kWh (at 3.6 X 106 joules or 3412 Btu per kWh at 100% efficiency) 2660 kWh at 33% efficiency of generation 50 grams of uranium present in natural uranium reactors (see note later under nuclear energy) 0.8 grams natural uranium in breeder reactors Nuclear and hydro electricity are expressed as the coal equivalent required to produce, at 33 per cent efficiency, the same amount of electricity. In other words, electricity produced by these sources is converted to its coal equivalent at the rate of 2660 kWh = 1 tonne coal.

Jan 1, 1978

By B Lumsden

During periods of high metal prices and strong metal demand tailings retreatment can be economic. Most tailings retreatment operations are technically challenging, low margin operations, because the easily recovered mineral has already been removed, therefore, process improvements can potentially yield large economic benefits. The Hellyer tailings dam was owned by Intec Ltd and contained 10.9 million tonnes grading 2.8 per cent zinc, 3.0 per cent lead, 88 g/t of silver, 0.16 per cent copper and 2.6 g/t gold. In November 2006 the Polymetals Group, as operator, restarted the Hellyer plant to retreat these tailings. Within a few months the operation had stabilised and Polymetals was meeting budgeted targets of throughput, metal recovery and concentrate quality. Polymetals and Intec then investigated methods that would improve the metallurgical result for this difficult to treat tailings. Since the tailings are fine-grained with 80 per cent <45 ¦m, magnetic aggregation of the paramagnetic sphalerite was evaluated. Magnetic aggregation of an oxidised tailings feed has not been tested before, nor had the technology been available when Hellyer ore was originally processed. Extensive statistical test work showed magnetic aggregation of the sphalerite fines in the zinc cleaner circuit increased total zinc recovery. The increase in the mean zinc recovery with magnetic conditioning was 3.63 per cent, at a statistical level of confidence of 97.8 per cent, and at the same mean zinc concentrate grade.

Jan 1, 2009

By J P. Jona, S R. Poulson, C H. Gammons

Spatial and temporal trends in water chemistry in the acidic (pH ~2.6) Berkeley Pit lake, Butte, Montana, can be explained by a newly developed iron-cycling model. Key elements of this model include: subaqueous oxidation of pyrite and other metal sulfide minerals by dissolved ferric iron, producing Fe2+ as a by-product; re-oxidation of Fe2+ to Fe3+ in the epilimnion, assisted by A ferrooxidans; precipitation of secondary ferric minerals (schwertmannite, jarosite) in the epilimnion; and replenishment of the Fe3+ concentration of the hypolimnion by seasonal lake turnover and gravitational settling and re-dissolution of ferric precipitates. Pyrite oxidation rates were approximated by using published rate laws and information on the Fe3+ concentrations (~5 mmol) of the Berkeley Pit as a function of depth. The results indicate that subaqueous pyrite oxidation may be releasing as little as 6 + 106 or as much as 600 + 106 moles of H+ each year to the lake; the large range reflects uncertainty in calculation of the specific surface area of pyrite in the flooded pit. This helps to explain the observation that the pH and metal concentrations of the Berkeley Pit have not improved with time since mine flooding began in 1983. Vertical cycling of ferric iron in the pit lake permits pyrite oxidation to continue in deep water, even in the absence of dissolved oxygen. This hypothesis is supported by preliminary stable-isotope data.

Jan 1, 2003

By N Belluz, L Johnson, N Wiwoho, P Manning

The Kucing Liar skarn deposit is located in the Ertsberg mining district, which also contains other skarn deposits and the Grasberg porphyry copper û gold deposit. The Ertsberg district is located in the province of Irian Jaya, IndonesiaÆs easternmost province. Mining development began in the Ertsberg district in 1972 with the mining of the Ertsberg deposit. Daily production in the district now averages about 230 000 tonnes of ore, with the bulk of the ore coming from the Grasberg open pit and the balance from underground mining of skarn deposits. During 1998, 45 218 additional metres of drilling were conducted to delineate and understand the Kucing Liar orebody. The deposit was first intersected in drill holes in 1994 and then was intersected in underground workings located about 1000 metres from the discovery drill hole in 1995. Initially, the two intersections were thought to be different orebodies but are now realised to be different parts of the same orebody. The Kucing Liar deposit consists of magnetite û copper û gold replacement and skarn mineralisation in favorable Tertiary and Cretaceous units. The deposit is approximately 2000 metres in length and averages about 200 to 250 metres in thickness. The width varies from 400 to 600 metres. Drilling in 1998 was directed towards delineating the deposit on its NW and SE ends and to determine its down dip extension. Reserves for the deposit at the end of 1998 stand at 320 million tonnes at 1.4 per cent copper, 1.4 g/t gold, and 5.3 g/t silver. Many important questions remain to be answered concerning the relationship of the Kucing Liar orebody to the major faults in the district and to the Grasberg intrusive complex which contains the Grasberg orebody. Continued exciting developments are anticipated as work to understand the deposit by drilling and geologic study continues.

Jan 1, 1999

By B Roache, J O’Brien, M Gray

Admixture use in cement products is commonplace in the construction and mining industries. Many Australian mines have an operational concrete batch plant and stock hydration control and water reducing admixtures. The benefits of admixture use, especially in shotcrete is understood and well documented. Cemented rock fill (CRF) is used to fill stope voids and create stable vertical and undercut surfaces at some Australian mines. These mines generally mix rock fill with a slurry of cement and water without the use of admixtures. Recently published work on optimisation of CRF mixes has mainly focused on the strength increases associated with changes to the mix grading proportions by the addition of fines, but not focusing on the potential benefits of admixture use. Admixture use in CRF may be the simplest CRF optimisation method, as the admixtures will often be added by the push of a button at the batch plant. A CRF testing program was undertaken to test the benefits of admixture use in terms of strength gain, using hydration control additives (HCA) and high range water reducer (HRWR) admixtures. Rock fill gradings were strictly controlled in the test process to allow clear definition of the difference admixtures provide in compression at 28 days. The testing results define admixture associated strength gains in a 6 per cent general purpose (GP) cement by dry weight CRF mix (131 kg of cement/m3). Costings have been developed to allow a mine operator to understand the cost benefits of admixture use in CRF due to reduced operating costs. Operational efficiency advances and a suggested admixture implementation plan for CRF optimisation is offered.

Nov 29, 2022

By L Nienaber

Mines, after becoming operational, often retain the same support and reinforcement designs developed in the feasibility study. These designs are conceived from limited drilling data and regional experience, thus having an empirical flavour. Empirical designs are perceived to be conservative, catering for a variety of failure mechanisms, which are not always present in mine development drives.This begs the question: If you were to invest in the necessary resources to obtain sufficient data and complete the required analyses for the different development drives in the mine, to engineer a support and reinforcement scheme with the capacity to match the demand of the rock mass, what is the difference in cost when comparing an empirical design to an engineered design?To answer this question, mine tunnels with different geometries and orientations, where detailed structural data was available, were selected for a comparative design exercise. Material cost, development cost, cycle time and professional fees for engineered and empirical designs were estimated. The outcome is summarised in the following paper that discusses the process followed and the results of the design comparison.

Mar 8, 2011

By L Mariano

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

Jul 11, 2011

By B J. Beven, A Harris, L Balzan

Fortescue Metals Group flagship operation, Cloudbreak, is located in the Pilbara region of Western Australia. The mine is capable of delivering an annualised production rate of 40 Mt/a. Positioned 50 km to the east of Cloudbreak is Fortescue’s Christmas Creek operation, which has a combined processing capacity in excess of 50 Mt/a. Following on from these successes, Fortescue advanced development of its western Pilbara mines at the 60 Mt/a Solomon Hub. These processing installations place Fortescue in a strong position to deliver on a guidance of between 155–160 Mt/a for financial year 2014/2015.As Fortescue enters a phase of asset consolidation and debt repayment over expansion, the business is commanding stronger performance through enhanced plant operating practices and mine site cost reduction initiatives. To this end, the strategic placement of instrumentation is an area being given greater consideration. Access to real-time information pertaining to conveyed materials is of major interest to operators for making timely process control decisions. Fortescue has recognised the importance of accurate and up-to-date process information about their ores and hence, has adopted the use of Scantech’s Geoscan mineral analysers at two of their mines.There are two Geoscans at Cloudbreak; one on the ROM feed conveyor and another on the final product conveyor. These allow the in-feed material grade characteristics to be assessed. Moreover, the final product stream can be monitored to ensure product quality is maintained within acceptable quality tolerances. A third Geoscan is installed at Christmas Creek mine on a conveyor that transfers final products to Stockyards.This paper discusses the use of the Geoscans in these installations, including benefits to Fortescue’s operations, as well as functional considerations such as the impact of maintenance and calibration. A discussion of recent advances by Scantech is provided including enhancements to the calibration process and minimising plant downtime, along with a summary of results obtained.CITATION:Balzan, L, Beven, B J and Harris, A, 2015. Geoscan online analyser use for process control at Fortescue Metals Group sites in Western Australia, in Proceedings Iron Ore 2015, pp 99–106 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M P. Sandy, R M. Stephenson

Portals to access underground mines are important infrastructure and their design requires careful consideration. Portals are generally expected to last for the life of the mine. Typically, the exposure of personnel and equipment is high, with many hundreds of movements through the portal per day. Consequently, the risk associated with geotechnical instability must be extremely low. Portals are often established from a boxcut. In areas where the weathering profile is well developed, the design and execution of the boxcut can involve significant effort, with the objective of minimizing the volume of the boxcut, whilst ensuring that conditions at the design depth are suitable for establishing a stable portal. Properly designed site investigations are a critical part of this process. Currently available portal design guidelines have not been updated for decades, however the equipment and ground support systems have changed significantly in recent years. Many mine portals have since been constructed in a relatively short time frame with success, often in challenging ground conditions using some of the more modern approaches to ground support. This is beneficial because delays in establishing a portal will generally delay other critical path activities, and lead to cost overruns.

Mar 15, 2021

By L Soebari, W Sunyoto

The Wabu Ridge Gold Skarn deposit is located at elevations of up to 3100 metres above sea level, in the Central Highlands of Irian Jaya, Indonesia, 35 km NNW of the Grasberg porphyry deposit. Wabu is a grass-roots discovery in an area with no previous gold mining history or record of gold mineralisation. A geological resource of 117.26 million tonnes at an average grade of 2.16 g/t Au (1.0 g/t Au cut-off) has been defined to-date. Mineralisation is hosted within a skarn occurring along the southern boundaries of the Late-Miocene age monzonite-diorite Pagane intrusive complex. The intrusive complex occurs in the footwall of a major EW structure, the Derewo fault, which displays sinistral strike-slip and reverse fault movement. The Derewo fault separates Derewo metamorphic units to the north from platform sediments of the Australian craton to the south. The skarn has a strike length of 6 km and is up to 1.5 km wide. It is developed within calcareous shelf sediments of the Tertiary New Guinea limestone group and is dominated by prograde garnet development. Gold mineralisation was deposited during retrograde alteration and is directly associated with arsenophyrite and bismuth minerals. Retrograde alteration is distinguished by a sequence of clinopyroxene , magnetite, epidote and hornblende, biotite and chlorite and lastly carbonate. Gold is associated with the biotite/ chlorite phase together with sulphides and precipitated as the result of fluid mixing. The Wabu Ridge Gold Skarn deposit was identified in April 1990 during a regional program of helicopter assisted stream sediment sampling of -80 mesh (180 microns) fraction and panned concentrate sampling. The initial discovery sample site was situated 15 km down stream from the deposit and returned 1.49 ppm Au for the stream sediment sample and 138 ppm Au for the panned concentrate sample. A regional airborne helicopter magnetics survey, conducted in early-1992, helped defined the main magnetite associated skarn zone and the extent of associated igneous rocks. Detailed follow-up commenced in May 1992 and consisted of detailed mapping, soil sampling and ground magnetics prior to drilling the first hole in October 1992. Drilling to-date has delineated a contained geologic resource of 8.1 million ounces of gold and potential exists for a larger resource.

Jan 1, 1999

By E Widzyk-Capehart

The mines of the future can be envisioned as complex, large-scale technological systems being operated remotely from few centrally located (major cities) operating centres and skeletal crew stationed at the site. These systems will require remotely located human operators to constantly adapt to new and unforeseen system and environmental demands. In addition, the remote operators will need to match system properties to the changing demands and operational conditions, ie must be able to handle the ‘non-design’ emergencies, because the system designers would not have been able to foresee all possible scenarios of failures and provide automatic safety devices for every contingency. Therefore, it is highly important that the operators’ job, which involves problem solving and decision making at the workstation level, is facilitated by the proper interface designs. This paper argues that decision support systems and thus human-system interfaces for the mines of the future should be developed based on the principles of human-system integration that take into account human information processing and cognitive abilities. The information presented to the operator must support the operator in taking appropriate action through a human-system interface designed according to scientific principles of User Centred Design. A case study is presented where an iterative design process was used by CSIRO researchers as an evaluation method involving users (control room operators) at several stages of the user interface design in order to correct any design inadequacies as they emerged. This process allowed the designers to identify any usability issues before the user interface was fully implemented, which subsequently enabled the control room operators to easily adapt to the new interface and carry out all designated tasks in a timely and effective manner.

Nov 22, 2011

By P Wood, S Leveritt

This paper will introduce some innovative strategies for simulator training that are intended to improve the level of safety and operational performance of heavy equipment operators. The key strategy is to design simulator training to deliver improved work performance outcomes. This strategy is underpinned by a process for engaging workers in knowledge discovery and transfer that has been developed as an outcome of an Australian Coal Association Research Program (ACARP) funded project conducted at open cut coal mines in Australia. The process is expected to deliver improvements in the safety and operational performance of heavy equipment operators by informing training content about how experienced operators manage unexpected situations around the site. Tapping into the tacit knowledge that experienced operators gather over time can provide site specific and timely information about situational cues used to manage the unexpected. This type of information complements basic skills training by helping the trainee understand the operational context in which the acquired skills will be applied. Inexperienced operators have traditionally gained experience through their own actions, observing the actions of others and by taking the advice of mentors who have æbeen there, done thatÆ and developed operational decision making skills for safe and productive work performance. Leadership and mentoring techniques that contribute to effective knowledge delivery will also be discussed.Other simulator training strategies include refresher training, change management, emergency response training and testing the usability of new equipment and technologies prior to their introduction on-site. A key challenge ahead for the resources sector is the development of knowledge elicitation techniques that suit the operational workforce. A challenge for simulation and modelling professionals is to develop and refine techniques that support cost-effective customisation and regular updates of simulator scenarios.CITATION:Leveritt, S and Wood, P, 2012. Raising the simulator training bar - Strategies for improved work performance and effective utilisation of site-based simulators, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 65-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By P C. Miclea

Transportation networks extend every day around the world, requiring safe and well-maintained structures for efficiency and for users’ safety. Due to specific features of the infrastructure, such as longer tunnels, increased traffic and marginal safety rules, fire safety in rail and road tunnels becomes more challenging.The situation becomes more critical due to the global economy and increasing worldwide tourism, with multi-national companies often involved in both design and construction of transportation routes or systems in other countries. Tourism brings the risk of visitors becoming victims in a foreign land; thus, international law becomes more and more applicable to transportation projects all over the world, requiring a consistent approach to safety (UN Economic and Social Council, 2001; US DOT Federal Highway Administration (FHWA) 2006; US Transportation Research Board, Committee on the Role of Public Transportation in Emergency Evacuation, 2008; UK Parliamentary Office of Science and Technology, 1997).There are significant differences between rail and road tunnels, both in their functionality and safety requirements. Most tunnels over a certain length are equipped with emergency ventilation systems capable to control the spread of smoke by creating an air stream in the desired direction. Besides ventilation, fire-life safety (FLS) includes smoke and heat detection by linear or spot detectors, closed-circuit television (CCTV) and public address systems with prerecorded announcements, as well as evacuation signage and monitoring capabilities (Vägverket – Swedish National Road Administration, 2004).There isn’t a consistent, worldwide approach to the design of emergency ventilation systems for tunnels, with significant differences from continent to continent (US DOT Federal Highway Administration (FHWA), 2004, US Federal Transit Administration, Transportation Research Board, 2006). In North America US NFPA 130 and 502 standards for rail and road tunnels, respectively, represent the main criteria, however, they are continually revised and new versions issued every three years. For road tunnels the World Road Association PIARC issues guidelines, but they are not truly enforceable. There are no similar international guidelines for rail tunnels, except general recommendations by the International Association of Public Transport (UITP) (IAPT, 2003).In Europe the Directive #54/EC adopted by European Community Parliament in 2004 requires a minimum level of safety for road tunnels users in all existing and proposed tunnels in the Trans-European road network that are greater than 500 m in length. Authorities having jurisdiction in many other individual countries, such as Australia, Austria, Germany, Japan and others, enforce specific safety regulations (Miclea et al, 2007). While it is impossible to summarise all aspects of this topic in a short paper, a review of the design approach, the existing differences in safety requirements, as well as applicable design solutions to meet safety codes for both rail and road tunnels are discussed below.

Mar 8, 2011

By R Strand, L Reading, G Keir

A major challenge in managing coal seam gas (CSG) water is predicting how much water will be produced as the industry develops. Klohn Crippen Berger Ltd (KCB) was commissioned by the Queensland Department of Natural Resources and Mines (DNRM) to develop a tool to forecast where, when and how much CSG water will be produced in the Surat and Southern Bowen Basins under various industry expansion scenarios.The water production tool (WPT) uses the Theis equation, a non-equilibrium groundwater flow equation that accounts for the effect of pumping time on well yield in confined aquifers, to predict water production volumes. Where multiple pumping wells are in close proximity, the required pumping rates for coal seam depressurisation are reduced. Therefore, pumping effects are projected spatially to assess interference effects between wells. Water production is then upscaled to the projected scale of the CSG industry within the Surat and Southern Bowen Basins.Two modifications were made to address the dual phase nature of CSG extraction (a transmissivity reduction factor) and the impact of weathering at the eastern margin of the Surat Basin (a ænear edge effectÆ factor). These factors modify relevant hydrogeological parameters in a consistent and defensible manner to more closely match observed water production.The WPT was verified by comparing results to equivalent Theis equation calculations and to type curves provided by CSG proponents. Calibration was achieved by varying the spatial distribution and intensity of the near edge effect factor in conjunction with a chi-squared analysis of residuals.The tool, which is now being maintained and further developed by the Centre for Water in the Minerals Industry (CWiMI), was built to balance numerical complexity against relative flexibility and simulation speed. The result is a tool that can produce statistically relevant results of prescribed scenarios to plan water handling and treatment requirements in discrete zones of operation.CITATION:Strand, R, Reading, L and Keir, G, 2013. Water production simulation tool for coal seam gas operations in Bowen and Surat basins, in Proceedings Water in Mining 2013 , pp 311-320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By S Watson, L Martinez

Mine projects are complex opportunities that demand a constant assessment of uncertainty, ie risk and upside potential. This is because the value of a mine project is typically influenced by many underlying economic and physical uncertainties, such as metal/mineral prices, metal/mineral grades, costs, schedules, quantities, and environmental issues, amongst others, which are not known with much certainty at the beginning of the project. But, is uncertainty an enemy or an ally of the mine planner/analyst? To answer this question, this paper first assesses and elaborates upon the general concept of uncertainty. It then looks at the different sources of uncertainty in a mining project, such as the orebody, costs and product price uncertainties, and their effect on the final project value. Next, a general?review?of current mine evaluation techniques highlighting their limitations when dealing with uncertainty is made. Finally, an extended evaluation and risk management framework that addresses the existing uncertainty in the (greenfield/brownfield) mine evaluation process is proposed. One important characteristic of this framework is that it uses and manages uncertainty in order to generate additional value to the project; this is done through operational and managerial flexibility, which allow mine planners to minimise/maximise project risk/upside-potential giving a more realistic estimate of the projectÆs market value - this is shown in practical and simple examples occurring at different stages of a mine project, such as exploration and operation. Final conclusions are provided at the end.CITATION:Martinez, L and Watson, S, 2012. Uncertainty - An important source of (additional) value for mine projects, in Proceedings Project Evaluation 2012 , pp 131-140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By R Domotor

Brisbane’s Airport Link is Australia’s largest road infrastructure project, worth a total value of A$4.8 billion. The project is using surface and underground blasting to excavate hard volcanic rock, Brisbane Tuff. This paper tells the story of the most challenging and difficult blast of the whole project: the removal of a remnant pillar of rock (approximately 2250 m3) next to a major arterial road and within 100 m of existing infrastructure including a number of heritage listed buildings, residences and privately owned sensitive receivers. The pillar consisted of a hard rock wall (Brisbane Tuff) between 2 m and 6 m thick, 15 m high and 35 m wide; with in situ precast concrete piles embedded within 1 m of the boundary of the pillar. Orica Australia Pty Limited was contracted by Thiess John Holland, to perform the work in this area, including design, modelling, drilling and loading of the explosives, as well as blast clearance and shotfiring. Access to the area was limited so all explosives and equipment, including the 20 t drill rig, had to be lifted in and out by crane. Due to the nature of the blast, with infrastructure 5 m directly in front of the 15 m high face, there was only ever going to be one chance to get this blast right. This was an extremely complex blast which required the use of a number of different types of packaged explosives, as well as special timing techniques only made possible by using electronic initiating systems. This type of blast is high risk, and is more typical of a building demolition in the urban environment. The blast was fired on the 25 September 2010, and was highly successful. The environmental results for vibration and overpressure were well under the imposed limits, and the embedded concrete piles remained undamaged.

Nov 8, 2011

By M I. Pownceby, M A. Rhamdhani, D M. Fellicia, S Palanisamy, R Z. Mukhlis

The trend of global copper production has prospectively increased over time. Based on typical mined ore grades, 1 t of copper ore generates approximately 6–10 kg of copper, which requires much energy, usually in the form of metallurgical coke. Copper production using carbon as a fuel and reductant contributes up to 0.3 per cent to global greenhouse gas (GHG) emissions. As a result, research into decarbonisation processes applicable to reducing low-grade copper sulfide ores, copper oxides, electronic wastes and other alternative complex Cu-rich materials has increased. Alternative fuels for reducing carbon-rich emissions in pyrometallurgical copper processing include methane, ammonia, biomass, solar and wind power, but in recent times increased focus has been on hydrogen as a potential fuel and reducing agent for materials such as oxidised copper scrap, Cu2O/CuO and Cu-rich slags/e-wastes. From a thermodynamic perspective, hydrogen exhibits a significantly more negative standard Gibbs free energy (ΔG°) than copper oxide making it a suitable reductant and the exothermic thermal effect from reaction between hydrogen and Cu2O/CuO may be used to control process parameters. These characteristics renders hydrogen an ideal gas for reducing copper oxides and copper-containing slags/e-wastes. This review article assesses previous research on utilising hydrogen for producing and refining copper from primary and secondary feed materials.

Jun 19, 2024

By Hartley JS, Wills KJA

The Thalanga massive sulphide deposit is hosted by Upper Cambrian rhyolites and volcaniclastics of the Mt. Windsor Volcanics near their contact with overlying dacites, rhyolites and sediments of the Trooper Creek Formation. The ores and host rocks have been subjected to a single strong deformation and to lower to middle greenschist facies metamorphism. A main lens with surface gossan dimensions of 55U m x 6 m dips steeply, plunges shallowly to the west and is offset by a series of normal faults. It is flanked by smaller lenses to the east where the mineralized horizon is stopea out by granite. The area to the east and south of the gossan is masked by Tertiary cover. A complex exhalite package is represented by banded sphalerite-pyrite- galena-chalcopyrite, massive pyrite and chalcopyrite and assemblages dominated by dolomite, chlorite-actinolite, tremolite, talc, barite and rare gypsum. Accessory tetrahedrite, arsenopyrite, bismuthinite, magnetite and native gold are associated locally. Pods of quartz-magnetite formed distally. The ores are underlain by strongly to moderately pyrite-silica-sericite altered rhyolites with the strongest alteration closest to an interred synvolcanic fault. This alteration is characterised by an enrichment in MgO, Na2O, FeS2 and base metals with a depletion in CaO and Na2O. There is a general enrichment in Pb and Zn towards the hanging wall with some enrichment of Cu near the base of the main lens due to replacement by ore tiuias near vent discharge sites. Zonation of Cu to 2n-Pb in also evident over narrow intervals

Jan 1, 1987

By P Holtham, K Duffy, B, W Valery, E Tabosa, rade

Pre-concentration has potential to significantly improve Mineral Resource efficiency by removing gangue early in the process, before energy intensive and expensive comminution and fine processing. However, there are numerous options for pre-concentration and the performance and benefits of these are very case specific. To determine the best option for a particular deposit and to successfully integrate it into the overall mining and processing operations requires comprehensive evaluation. This needs to consider orebody suitability, technology capability and economic viability. The in-situ variability of a deposit and how it is influenced by mining methods and the liberation size of gangue are key factors which are generally not well understood. Geostatistical methods provide an insight into orebody variability, and the overall selection of any pre-concentration solution must be an integrated approach between geology, mining and processing. Many pre-concentration evaluations investigate the potential of just one option. Technology selection should start wide and may include: selective mining, pre-screening (with or without selective blasting), sorting (bulk and or particle), coarse gravity separation (e.g. jigging, DMS), coarse particle flotation, magnetic separation, etc. The upgrade performance of these processes is very ore specific and should be determined from testing, with detailed multi-component modelling used to determine the overall process performance. Many of these pre-concentration processes require significant ancillary equipment, feed preparation and materials handling. It is important to realistically estimate all costs to understand overall economics and select the best option. Some examples showing evaluation and comparison of pre-concentration options are presented in this paper. These include assessments of in-situ variability using geostatistical tools, process modelling of pre-concentration options and overall performance, preliminary layouts and cost estimates, and economic evaluations.

Nov 10, 2020