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By B L. Coulter, E Wightman, A S. Burrows

With their commitment to sustainable development in an increasingly carbon-constrained world, many resources companies are focused on reducing the energy required to create their final products. In particular, the comminution and smelting of metal-bearing ores are both highly energy-intensive processes. If resource companies can optimise the energy efficiency across these two processing stages, they can directly reduce their overall energy consumption per unit mass of metal produced and thus reduce their greenhouse gas footprint. Traditional grinding and flotation models seek to improve the efficiency of mineral processing, but they do not consider the energy used by downstream metal production, eg smelting and refining. Concentrators and smelters individually may be running efficiently, but are they optimising energy consumption of the overall system? A key step towards answering this question is to understand whether it takes less energy to remove an impurity in the concentrator or the smelter. Analysis of the complete concentrator û smelter process chain may show that there are times when the concentrator should use more energy to reduce the overall energy requirements across the mill and smelter. The new methodology discussed here will integrate downstream processing energy with mineral processing energy, to find the overall most energy efficient circuit design and operating strategy. The proposed methodology includes: determining what grade and recovery positions can be achieved in the concentrator by using different combinations and amounts of grinding and regrinding, thermodynamic calculations of the energy used to process the different concentrate grades to metal, and integrating the concentrating and smelting models to find the lowest total energy for the system. A case study which investigates the effect of increasing regrinding energy on the overall mineral processing û smelting energy consumption is presented. For the copper-nickel sulfide ore investigated the addition of regrinding results in 11 per cent less energy being used in the overall concentrator û smelter process chain per tonne of metal produced. Although regrinding is often seen as an energy-intensive process, in this case study the use of 1 kWh of energy for regrinding reduces the overall energy consumption by 12 kWh. The new mill to melt methodology will allow companies to model energy consumption from mill to smelter with a view to reducing the energy-intensity and greenhouse gas footprint of their processing and smelting operations.

Jan 1, 2009

By I Sherrell, R Jain

Worldwide iron ore feed grades are trending downwards and will continue to do so with the increasing difficulties of upgrading ores. This has led to operations looking for ways to capture current tailings that still contain valuable material. In the past, these were acceptable to dispose of, but this practice is no longer economically feasible. With the increasing trend of re-mining previous tailings deposits that could be decades old, new equipment designs have been introduced to upgrade current or historic beneficiation plants. These designs can effectively upgrade these tailings to saleable products.Outotec conducted test programs for upgrading iron ore tailings from flotation rejects, thickener underflow or tailings dumps on samples provided by customers around the globe. The studies utilised Outotec’s SLon vertically pulsating high-gradient magnetic separator in combination with preprocessing equipment such as low-intensity magnetic separation, screen or scrubber and flotation for downstream processing of the magnetic concentrate. A review of the equipment required to economically process these tailings is provided, along with testing data and industrial implementation examples. The effect of different operational and design parameters on Fe grade and recovery from processing each tailings sample has been highlighted.CITATION:Jain, R and Sherrell, I, 2015. Iron ore tailings reprocessing to maximise ore production, in Proceedings Iron Ore 2015, pp 149–158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By H Hoogvliet

The Goondicum Crater industrial minerals deposit is located about 30 km east of Monto, Central Queensland, Australia. Early exploration programs in the 1990s found alluvial ilmenite along the banks of the Burnett River. This mineralisation was traced upstream to the Goondicum Crater. The Goondicum Crater is a topographic feature centred on a roughly circular 6 km diameter layered gabbro complex. Significant ilmenite, apatite, titano-magnetite and feldspar mineralisation are present in a weathered horizon up to 25 m thick. After several drilling campaigns in the Crater and subsequent feasibility studies, the project was developed by Monto Minerals Ltd, an ASX listed company, in 2007. However, the project never achieved production performance expectations and ran out of commissioning funds. The company subsequently went into voluntary administration in August 2008.In 2009, the RMM Capital group, of Brisbane, took control of Monto Resources Pty Ltd, and renamed the company Belridge Enterprises Pty Ltd (Belridge). Belridge commissioned a redevelopment study aimed at recommencing mining and processing operations. As part of the redevelopment study the authors planned a drilling campaign, managed a quality control program and developed a block model. This paper describes the drilling program, analytical procedures, quality control procedures and the preparation of the block model.The block model for the resource estimate was created using 1 m high blocks, wireframes defining the main material types, and 2.5 m thick horizontal search ellipsoids with a radial pattern. The deposit was ‘flattened’ prior to modelling. To assist with the economic evaluation of the project, each block in the model was assigned a net dollar value based on economic parameters provided by Belridge, including anticipated revenues and costs. This modelling technique allowed for efficient investigation of various scenarios and was used extensively in the development and optimisation of the project’s financial model. At a zero net value per block, comparable to a break-even cut-off grade of four per cent ilmenite equivalent, the Indicated plus Measured resource is estimated at 51 Mt, averaging 4.1 per cent ilmenite, 1.9 per cent apatite and 2.5 per cent titano-magnetite.

Oct 5, 2011

By L J. de Lange

As a material asset for mining entities, the resources and reserves (RR) estimation processes are surprisingly underrepresented in the assurance landscape. When press reports expose them being inaccurately reported, or in merger and acquisitions processes, their importance becomes clear. The impact of erroneous RR numbers (both positive and negative) could have a material impact on an entity’s reputation and value.The technical nature and ‘black magic’ connotations of the RR estimation processes are possibly reasons why audit committees are not actively involved with it. Internal auditors avoid the RR processes for similar reasons. Also the traditional approach to obtain assurance on RR is expensive and is therefore only performed when it is absolutely required.However, stakeholders’ expectations of good governance are growing. Part of this increased focus is based on attaining a higher degree of certainty about the current and forecasted position of the entity. Stakeholders are also increasingly more interested in non-financial areas of entities, as the future success of an entity is more than a set of financial metrics.Consequently, the RR estimation processes should be visible on the agendas of audit committees. Monitoring of key controls is required as part of the governance obligations for senior management and the audit committee. So once it is on the audit committee’s agenda, the question then becomes, how will that agenda be supported by an assurance process that is cost-effective?The main objective of the paper is to describe a model of RR assurance that has been effectively applied in some mining companies. The paper discusses one particular approach that provides an audit committee with the required assurance regarding RR processes. The approach ties the assurance needs of the audit committee to the needs of the technical experts in the entity, therefore involving two important figures. It also offers assurance providers with a model to audit ‘through’ the RR processes rather than ‘around’ them. The paper then discusses top-down and bottom-up approaches that provide assurance at different levels of an entity.A governance audit that focuses on the RR processes is suggested as a top-down approach. A bottom-up approach assesses the design adequacy of internal control processes. A hybrid model is described which meets the needs of diverse stakeholders including the audit committee and the RR community.The hybrid model combines the expertise of professionals in both internal audit and RR. The right balance of these skills directed by a singular approach ensures that a credible result is achieved.This approach is not as expensive as some verification approaches used in the industry and can, as a result, be performed on a more regular basis.The last element of the paper looks at implementation of the reporting mechanism. An assurance process aimed at continuous improvement further enhances the robustness and reliability of RR reported by an entity.CITATION:de Lange, L J, 2016. Resources and reserve assurance processes – a framework for improved governance, in Proceedings International Mine Management Conference, pp 21-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By J Hutchings

An essential component to the management of any process is the measurement of key parameters, used to monitor, control, and provide the feedback necessary for improvement. This paper discusses how data collection and analysis can provide a better understanding of the blasting process, as well as additional control and improved outcomes.The drill and blast process involves the generation and use of information at a number of levels. Comparison of historical parameters and results provides a starting point for the development of ongoing blast designs and a baseline against which future results can be compared. The collection of data during implementation provides a quality assurance/quality control (QA/QC) function where potential defects (such as under-drilled or over-charged holes) can be rectified prior to firing. Actual quantities and production rates allow the development of realistic plans and schedules, rather than using inaccurate estimates and targets that lead to unscheduled changes to equipment paths. Over?the past several years there have been a number of technological advances in data collection technology. Drill monitoring instrumentation on blasthole drills provides location information and feedback on rock properties as drilling occurs. Hand held ‘data logger’ technology has also overcome the challenges of working on the bench, such that blasthole measurements can be collected and forwarded directly to the explosive truck. Mine sites are becoming wireless network-enabled allowing the seamless data transfer from the field back to the office, in near real time, as that information is collected. Great strides have also been made in the development of drill and blast software systems which are more user friendly, and yet provide far greater capability to manage the quantity of data generated. The blasting process is critical to the overall mining process and the delivery of a successful blast outcome requires that the blasting process be ‘in control’. The measurement of key parameters can provide the data with which to measure and maintain control of blasting, and allows the validation of performance improvement measures and identification of improvement opportunities.

Nov 8, 2011

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 A A. Latscha, D O’Connor

Increasing orebody complexity, restrictions in ground access, and longer lead times for disturbance approvals, have generated the need for the Resource Development Team within Rio Tinto Iron Ore (RTIO), to explore optimised drill design techniques that deliver resource conversion value while maximising program outcomes. In response to this challenge, the Team initiated a case study to produce an AI assisted/designed drill program using a non-machine learning AI. The case study involved the assessment and implementation of an AI generated drill program at one of RTIO’s Pilbara iron ore deposits, located in the Hamersley Province of Western Australia. The Mineral Resource is currently classified as 100 per cent Inferred. Access constraints inherent to topography, and the presence of exclusions zones have prevented adequate drilling coverage, resulting in lower resource confidence and a poor definition of the orebody extents and geometry. The drill campaign, planned in Q1 2023, needs to consider access constraints, complex topology and the limitations related to additional ground clearance, while addressing the requirement of improving orebody knowledge. The drill plan had to address two objectives. The first and main aim of drilling was to upgrade the Resource Classification to allow for possible conversion to Ore Reserve. The input for this objective was a volumetric representation of the areas currently not meeting pre-defined quantitative Resource Classification upgrade criteria. The second objective was to better define the orebody extents and geometry. For the second objective, the input to the drilling optimiser was a volumetric representation (blocks) of the areas of high uncertainty in the mineralisation/waste boundary, which were defined using an indicator conditional simulation technique. The drilling optimiser output was a range of compliant drill plans. A set of KPIs based on economic and orebody knowledge criteria were used to assess the plans and to select the most optimal drill design to be drilled in 2023. The geology and management teams were able to make better informed, objective decisions using the trade-off between cost and orebody knowledge gained. As part of the assessment, the AI generated plans were compared to our current planning practises. The AI assisted plans, when gauged against the project KPIs, showed clear and measurable improvements in both meeting project objectives and in managing operational risk.

May 24, 2023

By Mallett CW, Hammond RL

Geological maps of the Pacific Rim recently published by the Circum-Pacific Council for Energy and Mineral Resources have provided a useful perspective from which to view modern plate interaction and the evolution of modern fold belts. An important lesson from any study of modern plate interaction is that of the normality of change. The chaotic is more usual than the simple. Present day convergent margins with mixed characteristics are measures of this chaos. Indeed, the character of less than one third of the present length of the Pacific Rim can be ascribed to conventional models of plate interaction. Another lesson is that of the great mobility of oceanic crust. Enormous areas of the Pacific may not be represented in future fold belts developed at convergent boundaries unless normal consumption processes are disrupted, and even then only by linear zones a few kilometres wide. The axes of divergent boundaries creating Pacific Ocean crust have been equally mobile, with new spreading sites taking over from older sites through time. Divergent boundaries, whether active or inactive, consist of oceanic crust, and may be wholly consumed at collision sites with convergent boundaries. Their only potential contributions to fold belt evolution are transforms and magmatic activity. It is this transform component that can provide us with a mechanism to explain the apparent contradiction of both compressional and extensional features occurring together in a developing fold belt. Reconstructions for the SW Pacific are used to demonstrate that the fold belts under construction during the last 4% (Jurassic- Recent) of geologic time have involved interaction between convergent, divergent, and transform boundaries. In the last 15% of earth history (Late Proterozoic-Recent), many enigmatic features of the geologic landscape in Eastern

Jan 1, 1987

Mine pit slopes in the Pacific Rim are a geotechnical challenge because of the complex geology in which they are developed. Mines are currently being fast-tracked to meet the increase in commodity prices, often resulting in some reduction in ground studies and short-cutting of design procedures. In addition, the resources boom means that skilled personnel are in relatively short supply. At a time when mine pits are getting bigger and deeper, and the engineering is getting more demanding, there is an increased demand on managers to effectively implement the work.   Experience both in New Zealand and the Philippines, display the complex range of geological environments in which pits are being excavated. Working in these conditions has shown that successful geotechnical design requires a strong geotechnical model based on sound geology. An appropriate level of investigation and analyses results in a certain level of understanding for the mine design. There is a point where additional expenditure (on investigation and analyses) is not warranted based on the expected minimal impact on decreasing the level of perceived risk on the project. For most projects in our experience the analytical methods and complexity of geotechnical assessment changes increases as the level of knowledge grows.

Jan 1, 2006

An enhanced gravity concentrator was installed in conjunction with an intensive leach reactor at the Sadiola plant in Mali last year and commissioned in December 2007. There has been much debate over the years as to the effect of gravity concentration on overall plant performance. The late Dr Laplante suggested that for every ten per cent of gold recovered by gravity, there was a corresponding 0.1 per cent to one per cent additional overall plant recovery. The results at Sadiola are consistent with this hypothesis with an overall four per cent gain in plant recovery. With total gold recovery of 12 per cent in the gravity section, grades are increased from 3.54 g/t in the gravity feed to an average of 2 600 g/t in the concentrator feed to the inline reactor. The recovery of gold in the inline reactor is in excess of 98.5 per cent. This paper discusses the background to the project, the laboratory test work prior to the equipment selection, the operational results of the system, as well as the benefi ts of the future application of high mass yield centrifugal concentrators in base metals, sulfides and industrial minerals. Bench scale, pilot scale and plant practice examples are also presented.

Aug 1, 2010

By Kramadibrata S

Over the years many attempts have been made to develop a means of assessing the excavatability of rock. Most of them are based on an empirical rating system while some authorities still propose the use of seismic velocity as a direct predictor of the rippability of a rock mass. On the other hand there are a number of classical models which have been developed to define the cutting force required at the pick or tooth of continuous miners.While these methods have been applied with various degrees of success to the design of excavation systems there is no generally acceptable method of defining the excavatability or cuttability of a rock mass in terms of the machine power required to generate a particular rate of production.The authors have attempted to overcome this deficiency by recording the intact and rock mass properties at a number of surface mines where continuous miners were in use and to use this data to examine the relationships between the relevant dimensionless groups developed from a dimensional analysis of the problem.The results obtained are encouraging and it appears that this new approach to the problem could lead to civil and mining engineers having a means of predicting the cutting power required to excavate rock at a given rate at any site.While this paper does not include a review of past work it refers to a number of key publications which will give the reader an excellent introduction to the subject.It is important to point out that the research work reported in this paper is part of a doctoral research project at Curtin University of Technology on the Influence of Intact Rock and Rock Mass Properties on the Design of Surface Mines. One of the major objectives of this project is to explore the possibility of developing a technique for predicting the excavatability of rock in surface mines at the design stage.This paper therefore commences with a brief reference to the continuous surface miners in use at the test sites followed by some original work by the authors in applying Dimensional Analysis to analyse the macro-performance of mechanical excavators. Following an analysis of the experimental data the authors validate the wider use of the model by referring to its successful application in predicting the power required to excavate rock by continuous surface miners at other sites.

Jan 1, 1995

In the first half of 1987 two four metre diameter raise bore holes were drilled at the Olympic Dam Project for ventilation purposes. The first hole, 476 m x 4.0 m diameter was completed in 96 days, 35 days longer than scheduled. The second hole, 407 m x 4.0 m diameter was completed in 39 days, 2 days ahead of schedule. Both holes were drilled with a Robbins 121R rig using a Wirth head that consisted of 23 face cutters and 5 side cutters, supplied by a contractor. After the sites were located a grouting program was carried out to help seal off an aquifer between 160 and 180 m below the surface. Cavities discovered in the Andamooka Limestone were filled with concrete. Because of the overlying dune sands and clay both sites were pre-sunk to the competent Andamooka Limestone.

Jan 1, 1988

By S McKnight, L Koroznikova, J Begelhole

"This paper outlines a simple methodology for iron ore characterisation. Iron ores commonly contain a range of iron oxides with varying iron content along with generally minor quantities of lighter silicate gangue phases, giving rise to density variations. Companies tend to rely on heavy liquid separation (HLS) in the evaluation of samples arising from exploration, mining or metallurgical processes. Heavy suspension separation (HSS), a simple laboratory technique of density fractionation, employing suspensions of fine tungsten carbide (WC) particles in lithium heteropolytungstate (LST) solutions, can be used in the evaluation of iron ore.As part of Arrium Mining’s program to improve its knowledge of ore types being processed in two hematite ore beneficiation plants (OBP), metallurgical evaluation of hematite feed and geometallurgical evaluation for the OBPs has become a major focus.Metallurgical evaluation of the hematite ore ultra-fine size fraction, formally treated as waste but now upgraded by HSS, is a part of Arrium’s program to improve recovery.The HLS method for iron ore characterisation is not generally used as part of routine iron ore feed metallurgical evaluation due to the expense, toxicity and time-consuming nature of the technique. Results show that the HSS method for iron ore characterisation can achieve low-cost, low-toxic separation and can be used on-site to improve turnaround time of results (Begelhole, Jasper and Koroznikova, 2013).Arrium have applied this technique successfully for the past three years to progress process improvement for the two OBP as well as to assist Arrium’s on-site laboratory services, Bureau Veritas in Whyalla.The main objective of this program has been to further develop the HSS procedures using a low-toxicity, high specific gravity (SG) suspension; LST and WC as the dense medium for metallurgical evaluation of ultra-fines.A suspension of a particular density will separate iron ore into two products: a sink fraction (denser iron oxide – hydroxide particles) and float fraction (silicate – iron ore composite particles). A theoretical grade and mass recovery can be calculated, and a grade – mass recovery curve can be constructed for iron.Metallurgical evaluation of the plant feed ultra-fine size fractions are used to improve efficiency of an upgrading plant process. This type of characterisation can be used to prepare feed piles of known processing characteristics, or to benchmark the performance of the process against what can be theoretically achieved.CITATION:Koroznikova, L, Begelhole, J and McKnight, S, 2016. Characterisation of Low-grade Hematite Ore Ultra-fine Size Fraction Particles by Heavy Suspension, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 327–334 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By R Schmitt, Y Ghorbani, I McElroy, N J. Bolin, M Parian

Aitik is a large copper porphyry type deposit located in northern Sweden, currently exploited at an annual rate of approximately 45 Mt. The ore’s exceptionally low head grade of 0.25 per cent Cu and varying degrees of hardness across the entire deposit pose challenges to the two fully autogenous grinding lines, each of which comprises a primary autogenous mill in series with a pebble mill. The variability in ore grindability frequently leads to fluctuations in mill throughput. Within the framework of a geometallurgical approach, the present study investigated the relationships between ore grindability and modal mineralogy. For this purpose, drill core samples from different lithologies were subjected to Boliden AB’s in-house grindability tests. This fully autogenous laboratory-scale test generates a grindability index mainly related to abrasion breakage, which is a significant breakage mechanism within autogenous mills. The test results suggested divergent degrees of grindability within and across the selected rock types. A combination of scanning electron microscopy, X-ray powder diffraction, and X-ray fluorescence analyses was performed for the grinding products and bulk mineral samples. The resulting mineralogical and elemental properties were subsequently correlated to the parameters from the grindability tests. It was shown that the main mineral phases, such as plagioclase, quartz, and micas, correlate well with the grindability indices. Similar correlations were found regarding the sample’s chemical composition, attributable to the main mineral phases. A further inverse correlation was established between the sample’s calculated average Mohs hardness and the grindability indices. Moreover, mineral liberation information provided by scanning electron microscopy was associated with the parameters mentioned earlier. The identified relationships between grindability, modal mineralogy, and element grades may help Boliden develop a predictive throughput model for Aitik based on the mine’s block model.

Aug 24, 2022

By P Crittenden

Thiess Pty LtdÆs Australian Mining business unit used 7.6 PJ of energy in the 2007/2008 financial year. This represented more than 85 per cent of Thiess Pty LtdÆs total energy use and therefore meant that the Australian Mining business unit is required to conduct energy efficiency assessments and report publicly on the outcomes by December 2008 under the Federal GovernmentÆs Energy Efficiency Opportunities (EEO) Act. Thiess Pty Ltd has a policy commitment to sustainable development throughout its operations. This includes minimisation of its carbon footprint and the Australian Mining business unit has a strong focus on efficiency in all of its operations. It approached the energy efficiency assessment as an opportunity to further improve and build on its energy efficiency and greenhouse gas reduction focus in the business. As a mine contractor, Thiess faced a number of challenges in designing an assessment process that would be both effective and efficient to deliver. For example, unlike most other companies involved in the Energy Efficiency Opportunities program, the energy use associated with the Australian Mining business unit is not fixed to any single geographic location in Australia. Mining vehicles are moved from site to site according to the specific requirements of mine owners and the timing associated with the commencement and completion of contracts. Thiess departed from a traditional æsite by siteÆ based assessment and designed a ærepresentative assessmentÆ approach that involved detailed investigation of data across all sites and a focused assessment on a single site.Data and analysis was an essential part of the assessment and indicators at company, mine and site level were essential in identifying opportunities and tracking progress. Forty-six potential energy saving opportunities were identified and four of these are currently being implemented. The projects being implemented are: payload management, automating mobile lighting equipment, plant idle time management, and turbo idle downtime. The potential savings from the four major projects that have been identified are approximately 150 800 GJ/annum, equivalent to 10 600 tonnes of CO2-e/annum with a simple payback period of less than two years. Beyond the fuel savings however, there are a number of other benefits from the assessment, including operational efficiency, reduced maintenance costs and even a potential reduction in the number of vehicles required to complete the work. The EEO assessment has significantly increased the importance and urgency of energy efficiency and facilitated the sharing of good practice across all Thiess operations. Not only have four projects been adopted for immediate implementation but a further pipeline of projects is available for future possible implementation. This case study describes: how Thiess conducted its assessment including the use of energy data and indicators, the opportunities identified that are currently being implemented, and the lessons learnt and how other organisations can use these to improve their approach to energy efficiency assessments. This case study is a more comprehensive version of a case study developed for the Commonwealth Department of Resources, Energy and Tourism. The assessment results reported in this case study are drawn from the Thiess Energy Efficiency Opportunities Report 2008.

Jan 1, 2009

By R Sinclair, D Landwehr, I Hunter

"The Syama Gold Mine, located in southern Mali, was established in 1990 by Broken Hill Propriety Limited (BHP). The operation began treating oxide, and in 1994 it transitioned to processing hard and refractory ore based on ‘whole-of-ore’ roasting. In 1996, BHP was succeeded by Randgold Resources and the operation ran until 2001, when it was placed into care and maintenance.The Syama ore is classified as a double refractory ore with pyrite occluding the fine grained gold present in the ore and high levels of organic carbon presenting a challenge in terms of preg-robbing behaviour. The ore is extremely competent and this combination of metallurgical features was the main source of metallurgical problems encountered by the previous owners.Resolute Mining Limited (RML) acquired the Syama project in 2004. Following a feasibility study and the development of a revised processing flow sheet the plant was recommissioned in 2008 using a combination of old and new equipment. The revised flow sheet enabled primary sulfide ore to be treated by flotation and roasting of the concentrate to produce a calcine suitable for conventional carbon-in-leach (CIL) processing.Commissioning and ramp up of the plant was a troubled process, with monthly gold production being as low as 3000 oz in 2010. Poor availability of equipment and lower-than-forecast recoveries were the primary contributors.During the last five years, RML has utilised a systematic approach to improve production, focusing on mechanical reliability, metallurgical recovery and process bottlenecks. Modifications to the circuit have been as a result of both innovation and the application of technological improvements. Improvements have been made to the flotation, roasting and CIL circuits and RML has introduced a deslime circuit to treat flotation concentrate, in addition to the very successful commissioning of a new 1 Mt/a oxide circuit in December 2014. These changes have resulted in gold production increasing to more than 20 000 oz per month in 2015.This paper presents the processes, change implementation and outcomes of the modifications made to the sulfide circuit to address the availability and recovery problems.Apart from the expansion of an existing, world-class deposit and discovery of new resources, future improvements on the path to a class-leading gold mine include the continued reduction of the unit cash cost, increase in overall sulfide circuit gold recovery, increased throughput through continued innovation and consistency in the plant’s operation.Citation:Sinclair, R, Hunter, I and Landwehr, D, 2016. Syama Gold Mine - the Journey towards a Class-leading Gold Mine, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 213–224 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

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

Thermo Fisher Scientific is the worldÆs leading supplier of analysers for laboratories and process industries. The companyÆs X-ray fluorescence (XRF)-based slurry immersion probes were originally developed by the acquired Amdel Instrumentation. These analysers have found limited application within wet beneficiation plants for measurement of iron. The recent trend of renewed efforts to maximise recovery from existing resources and lower costs has increased industry interest in online analysis. In the mid-1990s the company developed online analysers (the light element slurry analyser û LESA) for slurry applications using the prompt gamma neutron activation analysis (PGNAA) method. The company has successfully installed LESA for the direct measurement of lighter impurity elements in Brazilian plants using flotation for rejection of silica. A case study is presented. The PGNAA technique has the unique ability to provide elemental analysis of bulk materials on a conveyor belt. The company released its eighth generation cross belt Omni analyser using PGNAA in 2007. Results from a recent project with sinter are presented. The Niton range of hand-held XRF analysers is also supplied by Thermo Fisher Scientific. These handy devices are finding widespread use in the mining industry to provide quick and easy analyses in exploration settings. In contrast to PGNAA this is a surface technique. A prototype for light element analysis is being tested for iron ore.

Jan 1, 2007

By Denby B

The ever increasing demand on land use has led to large areas of land being considered for development, which because of past mining activities are covered by substantial depths of fill materials. This paper examines the problem faced with the development of land infilled with open cast mining backfill, in predicting the behaviour of the fill upon development. To be able to design foundations suitable to withstand the movements that occur within open cast backfills or design a backfilling operation that produces land suitable for a proposed after development, a means of predicting backfill settlement is required. Factors critical to this prediction are the timing of backfilling operations, the compactive state of the backfill and the inundation of the backfill. The analysis of a considerable quantity of data collected from the monitoring of backfilling operations and backfill movement at a range of open cast coal sites located within the UK has given the authors a better understanding of how open cast backfills behave in terms of long-term creep settlement, collapse settlement and how these are effected by backfill scheduling. This knowledge has been encoded into a program running under Microsoft Windows that enables a user to make settlement predictions for a point, a given section or area or for the whole site. Differential settlements, critical to any development design, can also be determined between any two points taking into consideration the heterogeneous nature of open cast backfills. The program was tested with data from an open cast coal site in the UK. Compaction monitoring during the placement of the backfill material enabled a model of the backfill to be constructed taking into account backfill properties and scheduling. This model, taken as input into the program, enabled future backfill settlement predictions to be made. A comparison is given between these results and actual settlements obtained from a short-term settlement monitoring scheme.

Jan 1, 1995

By A J. Weston

Block or panel caving technology is far removed from that of the top slicing and block caving of the late nineteenth or early twentieth centuries. The rapid mechanisation and expansion of these methods in the late twentieth century was as much a result of the change of the technology of the unit operations of development, ground support, drilling and blasting and transport as it was of the advances in geotechnical understanding and practice. The small footprint gravity and scraper block caving mines with boundary weakening, rail transport and shaft hoisting of the early to mid-twentieth century have been replaced by massive high lift panel caves using preconditioning of the ore, large load-haul-dump units, adjacent crushers and conveyors to surface. The technology changes in the unit operations are described and the drivers for these changes examined.CITATION:Weston, A J, 2016. The evolution of block caving technology, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 265–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016