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By G R. Ballantyne, G Lane

Dry milling circuits that include high pressure grinding rolls (HPGR) or vertical roller mills (VRM) and air classification have replaced dry ball milling in cement production, but how do they compare to wet milling and classification circuits in mineral processing plants? Two case studies are presented that compare the energy efficiency, wear, liberation and capital cost of dry and wet milling circuits. In both case studies the VRM and HPGR consume half the energy of a wet tumbling mill for the same duty. However, the dry classification system tends to significantly erode the energy benefits. A number of improvement opportunities are presented that have the potential to improve the energy and capital efficiency of dry milling circuits. These improvement opportunities focus on the dry classification system that consumes significant energy in heating and fan power requirements and requires a large proportion of the footprint.

Aug 24, 2022

By A Reid, A W. Musk, O Jones

In this paper, the authors attempt to bridge the gap that currently exists between the duty-of-care responsibilities of underground mining industry personnel, and the multifaceted health challenges facing mineworkers in Western Australia’s metal mines where diesel-powered mobile equipment predominate. In addressing this issue, the complexities of the nature and extent of the challenges are discussed along with the current inadequacy of existing regulatory metrics. Support is given to the need for well-organised in-mine baseline studies to clearly define the distribution and aging characteristics of the toxic and carcinogenic pollutants within the mine ventilation system, with special emphasis given to exploring the validity of biomonitoring systems. The paper concludes with the proposal that a template risk assessment data sheet be prepared for the industry to provide mining personnel with a sound basic knowledge of the health risks involved and the control measures and precautions available for minimising and/or eliminating the hazard.CITATION:Jones, O, Musk, A W, Reid, A and Davis, C, 2017. Risk assessment tool for mines using diesel-powered mobile equipment, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 151–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By G Lane, M Bueno

In a recent publication (Bueno and Lane, 2011) the authors presented the analysis of a consolidated dataset composed by 137 autogenous/semi-autogenous grinding (AG/SAG) mill pilot trials. By comparing the measured data against theoretical specific energy consumption, the analysis indicated which circuit configurations were more or less energy efficient. However, the analysis has also indicated that the energy efficiency of each of the types of circuits vary significantly.There are numerous factors that contribute to the variations of energy efficiency of AG/SAG mill-based circuits, such as feed size distribution, recycle ratios and ore characteristics. In view of this, the present work accesses these factors individually and discusses what may lead a particular circuit configuration to be more or less efficient in terms of energy and costs.CITATION:Bueno, M and Lane, G, 2012. Key drivers of energy and cost efficiency in autogenous/semi-autogenous grinding circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 113-118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By H Lieberwirth, M Pfeifer, F Heinicke

HPGRs (high pressure grinding rolls) have been developed within the last decades for energy efficient processing of a wide variety of ores. Special interest has been raised by projects increasing the capacities of processing plants by installing HPGRs prior to ball mills. Bond ball mill tests have been used for decades as a base for ball mill dimensioning in mineral circuits. For final CAPEXOPEX considerations of the processing circuit, one key question is about the level of grinding energy split between HPGR and downstream grinding stages. This is especially interesting if the downstream process comprises multiple grinding stages combined with separation steps. The paper presents investigations on grinding energy consumption, size distribution and microfracturing of HPGR products, which affect the efficiency of the whole comminution and sorting process.

Aug 24, 2022

By G R. Power

A useful way to assess potential productivity of SLC mines is by quantifying tonnes/drawpoint/day to be extracted from the mine. However limited industry information has been published to help mines benchmark this number. This paper assesses industry data which can be used to support estimates of potential productivity from new mines based on tonnes/drawpoint/day. The information used has been extracted from historical production schedules which indicate what was achieved, rather than what was planned. It has been assessed using an algorithm created for the purpose and is presented with discussion of varying definitions of active drawpoints, analysis of the data and inquiry into some of the underlying contributing factors.

Mar 15, 2021

By P T. Stoker, A Allman, D P. Carville

Classification of mineral resource estimates is one of the most important responsibilities of the Competent Person. In recent years, classification decisions have been driven more by the detailed block-by-block attributes generated by the now widely applied geostatistical estimation methods, and less by a general geological overview. This is increasingly resulting in æspotted dogÆ outputs, in which blocks of Inferred Resources or unclassified material separate blocks of Measured and/or Indicated Resources, or individual drill holes are surrounded by annuli of Measured and Indicated Resource blocks. Not only are such outputs potentially misleading, since they ignore fundamentals such as continuity of geology and mineralisation between drill holes and the imprecise nature of resource estimation, they can also cause substantial problems for engineers undertaking mine designs and estimating ore reserves, particularly for underground mines. Competent Persons for mineral resources must keep in mind the purpose of their work, and should use their experience and judgement to avoid or smooth out æspotted dogÆ classifications, providing a result commensurate with the level of geological and resource estimation confidence. For their part, ore reserve Competent Persons must understand the resource estimation and classification process, and should question resource classifications that are not consistent with the level of geological and resource estimation confidence.

Jan 1, 2006

By S Ferguson, G Noble

The mining industry is facing economic pressures to treat more challenging and lower grade ore types, as well as pressure relating to environmental impact and social license to operate. Preconcentration through bulk ore sorting has the potential to benefit all these areas by enabling mining operations to divert material of low economic value prior to processing, thereby achieving higher feed grades and recovery, while reducing the processing plant and tailings dam footprint and capital required throughout the life of mine. The effectiveness of bulk ore sorting depends on the heterogeneity of material at the measurement location, as well as the accuracy and precision of the measurement. An understanding of ore heterogeneity can be assessed using drill core data, which provides metre by metre elemental assays. This paper reviews such data and assesses the grade distributions over different scales, which suggests that sufficient heterogeneity exists at mining scales to allow the potential for bulk ore sorting. Prompt Gamma Neutron Activation Analysis (PGNAA) technology has proven to be a successful measurement technique within many industries, including mining. PGNAA was first developed in the early 1980’s for the measurement of the elemental composition of bulk materials on a conveyor belt. Today, Pulsed Fast Thermal Neutron Activation (PFTNA) technology is also applied in elemental analysis of bulk materials and has some advantages for bulk ore sorting. In order to enable effective bulk ore sorting, however, a PGNAA/PFTNA analyser must be designed to provide a representative bulk ore analysis with the necessary accuracy and precision. Examples are presented to provide an understanding of the factors affecting PGNAA/PFTNA performance in relation to effective bulk ore sorting.

Nov 10, 2020

By T Honeyands, L Jelenich

We are currently witnessing large fluctuations in the relative price of ironmaking raw materials brought on by changes in the dynamics of supply and demand, market conditions, environmental regulations and technical factors affecting the iron and steelmaking process. From a customer perspective, it is the behaviour of iron ores in downstream processing that give them their value; their impact on the sintering or pelletising process and subsequently blast furnace ironmaking. It is therefore important to consider this value when developing projects, making mine planning/cut-off grade decisions and in setting price differentials for differing quality.This paper describes the use of the Marx value-in-use model to quantify the downstream value of lump iron ores. The Marx model consists of heat and mass balance modules for sintering and pelletising and a rigorous two-stage heat and mass balance model of blast furnace ironmaking. Mass balance and cost models are applied for steelmaking, casting and rolling. The use of a heat and mass balance allows accurate comparison of the impact of raw material properties on blast furnace operation. The impact of minor elements, such as alumina, silica and phosphorus, and metallurgical properties on ironmaking is described, and examples are given for the calculation of a lump premium.CITATION:Honeyands, T and Jelenich, L, 2015. Lump ore properties and their impact on value-in-use in ironmaking, in Proceedings Iron Ore 2015, pp 359–362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By P McCarthy

The relatively new field of geo-metallurgy promises to improve the predictability of mill feed quality and enhance processing outcomes. However, it is subject to the same limitations as the prediction of grade using geostatistics and has additional limitations due to the spatial distribution of the variations being measured and the sample sizes required. Schedules based on geo-metallurgical models will, in turn, be subject to variations arising from geological control and practical mining constraints.This paper discusses the key drivers of variations in mill feed quality and quantity from a mining perspective. It concludes that geo-metallurgical modelling addresses only one aspect of the problem. A case study is provided to illustrate poor predictability of metallurgical performance even with very detailed geological data.

Aug 8, 2011

By T Elkington, A Finch

The theory of constraints (TOC) is a business improvement method that focuses on exploiting a business’s bottleneck to deliver the highest possible profit. Early applications were mostly in the manufacturing industry; however, the theory in itself is completely generic and has now been applied widely in other industries such as services, retail, software and distribution, amongst others. The intent of the approach is attractive – it focuses on the ‘silver bullet’ rather than ‘death by a hundred projects’, and it focuses on growth rather than cost cutting. Application within the mining industry has been limited to date, although there are a few applications emerging. This paper discusses how TOC can be applied to maximise value during the project planning phase and how to maximise profits when the mine is operational. The paper uses two case studies to illustrate the approach. Case study 1 uses the approach to improve tactical mine planning, which delivers an increase in revenue of 58 per cent. The second case study is a strategic mine planning example that delivers an increase in value of 77 per cent.CITATION:Finch, A and Elkington, T, 2014. Application of the theory of constraints to strategic and tactical mine planning, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 129–136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

A hidden asset in most exploration and mining activities is data. Common practice involves the spending of large amounts of money to discover, define and prove the viability of a mining project. Some organisations have used operations research analysis and internal costing methods to allocate a value to their data and to compare the costs of data maintenance to other more tangible activities like plant and equipment maintenance. Those organisations, which do not undertake such an analysis often, have little knowledge or understanding of the extent and the worth of their data. Often the organisations lack of knowledge and understanding of the data is indicated by their failure to fully exploit or realise their opportunities. The focus of this paper is to discuss new technologies that optimise the management and security of collected and derived data. The technologies discussed are components of the software systems acQuire and MineSight.

Jan 1, 1999

By R M. Yanamandra, S K. Tripathy, N Mangadoddy, P Sudikondala, P Ankireddy

Spiral concentrator is one of the most commonly used gravity concentration devices in mineral processing. The particles are classified based on their specific gravity and size. The present work analyses the experimental and numerical investigations of the water flow field, such as fluid depth and free surface primary velocity of two high gravity spiral concentrators at different flow rates. The measurement techniques use a flow depth gauge and flow visualisation technique adapting lycopodium powder as the tracer. Flow features in terms of liquid depth and primary velocity at the free surface of the flow are captured across the trough in two different high gravity spirals. A highspeed motion camera with an imaging frequency of 5400 frames per second and 768 × 768 pixel resolution is utilised to track the tracer particles in the liquid flow on the dark surface background. Further, the two-phase flow is studied numerically on high gravity spirals based on the volume of fluid (VOF) approach utilising the RNG k-ε model and Reynolds Stress Model (RSM) for predicting the fluid flow on trough surfaces such as water depth and free surface primary velocity. The CFD predictions of the flow field for the two spirals are attempted to validate against experimental data. The high gravity spiral concentrators show lower flow depths and free surface primary velocities but steep velocities on the outer trough zone compared to that of low gravity spiral concentrators (conventional coal spirals). Among the computationally tested high gravity spirals, higher pitch and higher secondary slope design shows greater flow characteristics.

Aug 24, 2022

By S Tierney, D Cumming-Potvin, I Thin, Y Potvin, D Grant

The preliminary modifying factors for future stope design in the Southern Mine Area of Olympic Dam consisted of only a single, arbitrary value of Equivalent Linear Overbreak/Sloughing (ELOS). In order to improve this, a study was conducted which developed a more comprehensive methodology for assigning ELOS, Equivalent Linear Lost Ore (ELLO) and Equivalent Linear Fill Overbreak (ELFO) to individual stope faces based on geotechnical and mining parameters. The approach used was to look at the simple cases, which were classed as vertical stope walls in good ground (RQD 80-100%), divided into wall orientations (North, South, East, West). The stope walls were also split based on the blasting practice used (toeing, parallel or a combination of the two). The expected ELOS and ELLO from these ‘base cases’ are then modified by parameters which have historically been found to affect stope performance (Hydraulic Radius and Q’). The size of the effect found in the historical data determines the ELOS / ELLO applied. The methodology was summarised in an easy to use flow chart and was applied to all of the proposed stope shapes for the Southern Mine Area and summarised per mining block. This allowed each iteration of the mine plan to be assessed in terms of overbreak (both rock and vertical fill exposures) and underbreak.

Mar 15, 2021

By A Whaanga, W Vigor-Brown

IGO Ltd’s (IGO’s) Nova-Bollinger Deposit (Nova-Bollinger) is a magmatic nickel-copper-cobalt (NiCu-Co) sulfide deposit found 160 km east-north-east of the town of Norseman in Western Australia (WA). The deposit is hosted by the Mesoproterozoic rocks of the Fraser Zone, which is part of the Albany Fraser Orogen (AFO). Since mining commenced in 2016, IGO’s Nova Operation (Nova) has mined and processed to 31 December 2020, 5.63 Mt of ore grading 2.04 per cent Ni, 0.86 per cent Cu and 0.07 per cent Co. Nova’s mine geology team (MGT) has used commercially available implicit modelling (IM) and general-purpose resource modelling (RM) industry software systems, to prepare the 31 December 2020 (CY20) update of Nova-Bollinger’s JORC Code reportable Mineral Resource estimate (MRE). This CY20 MRE update was predominantly based on ~386 km of diamond core drilling, with the drill holes having a nominal grid spacing of 12.5 by 12.5 m throughout the mineralised zones of the deposit. Using IM tools, Nova’s MGT interpreted and modelled 22 separate domains from the drill hole logging, assaying results, and the MGT’s underground mapping. These IM closed volumes were then used to control the estimation of MRE variables into conventional industry digital block models using RM and other ancillary software systems. During 2021, a commercial machine learning (ML) software was trialled by Nova’s MGT for preparing block models of Nova-Bollinger’s MRE domains. The motivation for the trial was that the ML process could expedite modelling through the direct creation of a domain coded block model from the drill hole logging. Compared to the industry standard approaches of wireframing or IM, where the modeller usually makes many subjective choices to produce the domain model, ML offers a more objective ‘hands-off’ process for determining the connectivity of domains defined in drill holes. Additionally, the ML process provides a quantitative confidence metric associated with its output that may have utility in mine production and resource classification. In this paper, the results of the Nova-Bollinger ML modelling trial are compared to the MGT’s current workflow for MRE work. The MGT’s conclusions as to the advantages and disadvantages of the IM and ML methods for preparation of MRE domains are discussed. The ML software was also tested as a method of rapidly interpreting geology outside the principal zones of MRE interest. These testing results are also presented in this paper.

Mar 22, 2022

By D Deb, R Pramanik

This paper presents a generalised methodology in smoothed particle hydrodynamics (SPH) framework to analyse dynamic failure process of rock mass having natural joint under blast-induced stress wave and expansion, and penetration of high pressure gaseous product. The necessary interactions of gas-rock are incorporated in the model which describes features of coupling between damage and plasticity in tension and compression respectively. A Drucker-Prager formulation of plasticity is used to model the behaviour of aggregate field and the Grady-Kipp damage model is employed for tensile strain. These two material behaviours are then brought together within the framework of interacting continua. The model relies on the Drucker-Prager plasticity surface to predict the dilatancy aspect of the material response and to account change of strength according to the strain rate effect. Three numerical examples are presented with rock joint and multiple blastholes.CITATION:Deb, D and Pramanik, R, 2015. Smoothed particle hydrodynamics modelling of blast-induced fracture processes in naturally jointed rock medium, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 65–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By W Zirima

A detailed, mine scale non-linear numerical model of Rosebery mine has been built for the purpose of simulating life-of-mine global deformations. The model was calibrated using observations of displacement and damage, and was then used to investigate the correlation between dissipated plastic energy (DPE) and seismic event occurrence. The study is unique because the seismic data was collected over a relatively short period using a temporary portable seismic system. It is the intent to undertake significantly more work, but the analysis of limited data shows that a very good, non-linear relation between DPE and event probability is present. The observed correlation is consistent with measurements from other mines where more data was available. With more data, the strength of the correlation will allow the DPE analysis to be used during the design and sequencing phase of planning to better design the mine to minimise seismic hazards.

Jan 1, 2008

By J Ireland, S Rose

The main outcomes of mining grade control include defining the boundary between ore and waste and then categorising the ore according to which stockpile it should be sent. A typical workflow includes using general mine planning software (GMP) – such as SurpacTM, VulcanTM or CAE StudioTM – to create three-dimensional wireframes of mineralisation domains, which are used to flag the relevant samples of interest and constrain estimation during block modelling. Creating the wireframes is a time-consuming process, requiring reasonable software skills, patience and an eye for detail. The interpretations can be subjective; indeed, even the same geologist will give different shapes if presented with the same data at different times. The process can become particularly tedious when trying to carry out updates due to new data. It can also be difficult to test the effect of alternative interpretations or grade thresholds because of the time constraints in production.There are now several implicit modelling tools available, either as standalone programs or as add-on modules to existing GMP. In this paper, the authors develop a workflow using implicit modelling methods to show how grades and geology can be rapidly interpreted to provide effective domains for grade estimation. The paper includes case studies from open pit gold mines. The implicit modelling approach can save several days of interpretation work for each grade control drilling campaign.CITATION:Rose, S and Ireland, J, 2014. Implicit modelling applied to grade control data, in Proceedings Ninth International Mining Geology Conference 2014 , pp 115–122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By D A. F Oliveira, C J. Parker

The role of the virgin in situ stress field in tunnelling projects is well known in the Sydney area. The effect of in situ stresses is mostly considered through the use of published relationships that describe the in situ stress conditions as a function of depth. Considering the significant scatter in the data, it is evident that by adopting such relationships, the designers are assuming an average distribution of stresses with depth that is generally a reasonable engineering approach; however, when building a geomechanical model, the tunnelling or geotechnical engineer needs to account for the interrelationship between ground conditions (rock mass quality – fracturing, strength and stiffness) and in situ stress, which may explain part of the stress data scatter. This paper presents an alternative approach for interpreting in situ stress conditions, valid for both Sydney sandstones and shales that focus on such interrelationship between in situ stress and ground conditions.CITATION:Oliveira, D A F and Parker, C J, 2014. An alternative approach for assessing in situ stresses in Sydney, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 189–194 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J Pan, B-J Shi, X-B Li

The granulation behavior of specularite fines which possess poor ballability was studied with limonite fines as a function of nuclei particles and adhering fines. The results show that the permeability of granules deteriorated as the ratio of specularite fines increased in the mixture, and the optimal granulation moisture content also decreased. The granulation kinetics results demonstrate that the adhering load of specularite fines increases rapidly within three minutes and then levels off. With increasing specularite fines ratio, the adhering speed is accelerated but the granulation duration needs to be longer to reach adhering balance. The microstructure of granule quasi-particles indicates that the fine limonite particles act as binders to bond together the specularite particles which are dispersed in the adhering layers. This can improve the adhering strength of the granules. Hence, the granulation behaviour of specularite fines can be improved by blending them with fine limonite ores which have high adhering capabilities.CITATION:Zhu, D-Q, Li, X-B, Pan, J and Shi, B-J, 2015. Granulation behaviour of specularite fines in ferrous sinter mixtures, in Proceedings Iron Ore 2015, pp 91–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M Chaudhari, G Manekar, D Shome

MOIL Limited is operating 7 underground and 3 opencast mines in central India and producing annually more than 1.2 million tonnes of various grades of manganese ore. The underground mines are operating at shallow - 90 m at Munsar mine to moderate - 353 m at Balaghat mine below the surface with horizontal cut and fill (HCF) or its variant method of stoping with post filling by hydraulic sand stowing. The Munsar mine is being worked underground since 1903. The opencast mining is presently stopped. The ore body below the opencast quarry is geological continuity of the area excavated in past by opencast method of mining. The underground mining is done through the adit in three levels i.e. 270’L, 220’L, 170’L and by incline in western part of the property at 70’L. The horizontal drift development has been developed in the manganese ore body with sill drive of 5 m above the sill pillar in lower level at 70’L and barrier pillar of 5 m thickness is left for protection of upper level at 170’L. Valuable mineral has been locked in sill pillar and therefore rock mechanics investigations have been carried out. On the basis of study now the drift development has been carried out in footwall rock at 70’L, (-) 30’L and below levels and it has improved the mineable manganese ore by about 20%. In this modified HCF stope design, an alternative fill material in place of sand, which has been developed in house by use of overburden (OB) material after treatment, has been used for hydraulic stowing. The experimental trials find out that the alternative fill material of OB is more compact and forming a non expansion floor for the men and machines in the stope. This will certainly help in the introduction of mobile underground mining equipment for drilling in the stopes and mechanical mucking, transportation and loading of the ROM. The paper presents rock mechanics investigations and future use of alternative fill material of OB for better safety and productivity at Munsar Mine of MOIL. CITATION:Manekar, G, Shome, D and Chaudhari, M, 2018. Modified ground support with alternative fill material for ground control at Munsar underground manganese mine of MOIL Limited, India, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 58–65 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018