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By M Swart, H Ståhlbröst, P Toor

Development of SAG liners has always been a strong focus and interest in mineral processing as SAG liners significantly impact on plant performance (throughput and grind size), material costs and plant downtime. SAG shell relines typically determine the frequency and duration of plant shutdowns. Early SAG shell liner designs relied heavily on practical experiences and were limited in their size due to weight restrictions. Significant developments in Discrete Element Method (DEM) modelling, material and manufacturing technologies and larger reline machines have resulted in new and improved liner designs. This paper discusses the evolution of SAG shell liner design and its progression to the Skip Row design. Case studies have been provided for the Skip Row design in a variety of applications such as Single Stage SAG (SSS), SAG and Ball (SAB), SAG and Ball with Crushing (SABC) and Pre-Crush at a variety of mill diameters ranging from 24 foot to 34 foot. A detailed assessment has also been carried out comparing liner service life, ease of reline and performance (throughput, power and grind size) for a large 34 foot SAG mill when compared to the previous design.CITATION:Toor, P, Swart, M and Ståhlbröst, H, 2017. The evolution of SAG shell lining and introduction of the skip row design, in Proceedings MetPlant 2017, pp 158–184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By H Ishikawa, H Zhou, M Spagnolo, R Halomoan, S Palaniandy

The Karara Mine concentrator commenced operation in November 2012 to produce high-grade magnetite concentrate. The circuit consists of three stages of comminution plus magnetic separation at each stage for early gangue rejection. High-Pressure Grinding Rolls (HPGRs) are used for fine crushing, followed by ball mills and TowerMills in secondary and fine grinding duties respectively. In recent times, the plant throughput rate has had to exceed design by 18% to maintain the targeted concentrate productivity. Meanwhile, the ore hardness has increased by 25% to 15 kWh/t, leading to changes in the circuit operation and design. These changes led to coarser and harder feed to the TowerMill circuit that affects the subsequent separation processes. Nippon Eirich (the TowerMill manufacturer) has partnered with Karara Mining Limited (Karara) to optimise the TowerMill circuit operation to achieve a circuit product with an 80% passing (P80) of 35 µm. Several activities, including a TowerMill circuit audit and performance evaluation, multi-component analysis, modelling and simulation, were carried out as part of the optimisation exercise. The circuit audit results revealed that the TowerMill circuit feed size F80 had increased and ranged from 67–75 µm. The circuit product P80 ranged between 42–55 µm. The average circuit specific energy was 3.4 kWh/t. Moreover, the differences in density between magnetite and gangue minerals had affected the hydrocyclone performance where the efficiency curve exhibits coarse end deflection indicating that low-density coarse material was bypassing to the overflow stream. A multi-component analysis was carried out to further investigate the coarse end deflection of the hydrocyclone efficiency curve. The analysis showed that the magnetite and gangue minerals had different cut sizes of 32 and 64 µm respectively. Furthermore, 33% of the magnetite (below 35 µm) was being recycled back to the mill due to the density effect. Based on these findings, several recommendations for process improvement were identified and implemented including:• converting to a bottom feeding configuration to improve the grinding efficiency in the mill• additional grinding power in the fine grinding duty to compensate for the increase in plant throughput and ore hardness• improved classification efficiency by converting to smaller size hydrocyclones. Simulation studies carried out to evaluate the impact of these implementations had indicated that a P80 close to 35 µm with a steeper size distribution could be achieved by using the bottom feed configuration with additional grinding power. The TowerMill circuit was converted to bottom feed configuration and the performance was evaluated. The operating work index, size specific energy and circulating load were 30% lower than the top feed configuration, indicating that the bottom feed configuration had a higher grinding efficiency. This paper discusses the outcome of the circuit audit, multicomponent analysis, circuit simulations, improvement strategies and quantification of the improvements. CITATION:Palaniandy, S, Spagnolo, M, Halomoan, R, Zhou, H and Ishikawa, H, 2017. Fine grinding circuit process improvement at the Karara mine concentrator, in Proceedings MetPlant 2017, pp 101–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By G Harbort, K Quan

Traditional engineering practice for concentrator design uses a mixture of risk minimisation options and capital minimisation approaches. Often this is based on the preferences and experiences of the engineers involved.A geometallurgical approach involves identifying primary lithology, alteration, and mineral dispersion patterns within a deposit to allow representative samples for test programs. This provides a method to infer from laboratory test results meaningful production data for larger amounts of the ore body. Geometallurgical models can be integrated into the resource block model and subsequent mine plan and can assist in predicting when difficulties in the processing route might be expected, allow adjustment of the design to compensate for these or provide an early warning system so that production forecasts can be more adequately developed. Simulation modelling is the process of creating a computer model of a real system based on mathematical logic. In simulated time, the model explores the randomness and chronological sequencing of events observed on real systems. The objective is to mimic the real system with sufficient accuracy to make predictions of real behaviour under experimental conditions. Amec Foster Wheeler often use the ‘discrete-event’ simulation modelling technique. This method is well suited for inclusion of the statistical variation of effects in unit operation, mechanical availability, throughput and operating strategy (based on historical operating data for equipment downtime), operating schedules and equipment capacity. The net result of the simulation model is an analysis that can quantify risks in terms of system performance and capital and operating costs.CITATION:Harbort, G and Quan, K, 2017. Concentrator design – standard engineering practice versus geometallurgy and simulation, in Proceedings MetPlant 2017, pp 195–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By M Hourn, G Anderson, V Lawson, P Voigt, D Mallah

As mine head grades decline and orebodies become more complex, traditional mineral processing techniques and flow sheets to achieve saleable concentrate become more difficult to design and construct. Mines with lower quality concentrates or concentrates with penalty elements are particularly under threat. The economics of such operations are far more susceptible to metal price fluctuations, concentrate treatment terms and the availability of other, cleaner concentrates. Additional value may be realised for these orebodies through improved recovery by producing a low grade middling concentrate for further processing, in conjunction with a saleable concentrate.The most economic effective way to reduce impurity levels is to do so as early as possible in the mining value chain. Technologies such as fine grinding and fine particle flotation are well established as effective methods for impurity rejection in mineral processing. What is often overlooked is how a hydrometallurgical process could also be integrated in the overall flow sheet to achieve higher overall recovery at the mill. In the base metals environment, this is probably because hydrometallurgical processes are associated with production of metal, or require the use of expensive and toxic precipitating agents once the minerals of interest are in solution. These processes can be very expensive, particularly with rising power costs and poor economies of scale in capital costs associated with low production rates from middling streams. Glencore Technology (GT) has recent experience in the treatment of middling and low grade concentrate streams and also tailings streams to complement a concentrator flow sheet in a refractory gold and base metals setting. The value proposition is the isolation of a low grade middling concentrate from the primary circuit or the tailings stream for upgrading to an intermediate product with an equal or higher grade than the primary concentrate to allow blending for sale. This allows the plant to operate on a more favourable part of the grade-recovery curve while avoiding the expense of metal production. For existing operations this is particularly attractive since it can be added to the flow sheet with no process interruptions. Two case studies are examined showing flow sheets and costings to arrive at the value proposition of the GT low grade treatment flow sheet.CITATION:Voigt, P, Hourn, M, Lawson, V, Anderson, G and Mallah, D, 2017. Economic recovery and upgrade of metals from middling and tailing streams, in Proceedings MetPlant 2017, pp 289–297 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By I Ritchie, G Lane, C Morley, D Yataco

Marcobre SAC (Marcobre) is developing the Mina Justa project in Peru. The project has a lower grade oxide orebody overlaying the higher grade sulfide orebody. The oxide ore is treated by acid leaching; consumption of acid is high and is managed by vat leaching rather than the more conventional heap leaching process.The leaching process uses ore crushed to 100% passing 8 mm to optimise copper recovery. Acid consumption generally increases with a higher proportion of fines. Marcobre is investigating a three-stage crushing circuit with high pressure grinding rolls (HPGR) in the third stage, instead of the more conventional four-stage cone crushing circuit. The use of HPGR can result in higher fines production due to the higher compression forces in the crushing zone. This paper reports on the outcomes of the test work completed by Marcobre in 2016 and 2017 to manage fines production and compare the use of HPGR with conventional crushing on a high acid consuming ore.At moderate pressing forces, a HPGR crushing circuit appeared to produce similar size distributions to cone crushing. On average, both the copper recovery and the acid consumption in subsequent vat leaching were higher with HPGR crushing than with cone crushing.CITATION:Lane, G, Morley, C, Yataco, D and Ritchie, I, 2017. Are there differences in size distribution when comparing conventional crushing and HPGR?, in Proceedings MetPlant 2017, pp 60–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By J D. Pease, J M. I Tuppurainen, P D. Munro

This paper examines how legislation and regulation can be external drivers of technical change in mineral processing and extractive metallurgy and how the industry can respond. Two examples are considered; the production of copper metal from concentrates and the cyanide process for gold production.The Clean Air Act (1970) in the USA initiated a wave of attempted innovations in the extractive metallurgy of processing copper sulfide concentrates to meet forthcoming standards on sulfur dioxide emissions. Interestingly, a satisfactory technical solution existed (flash smelting and gas capture) but had not been widely adopted.Nearly fifty years later the primary copper industry finds itself with new challenges. One major challenge is how to deal with the increasing level of arsenic in copper concentrates. Most countries impose an upper limit on arsenic in imported concentrate; typically, 0.5% As or less. Higher arsenic concentrates can be blended with cleaner ones to meet the limit, but this tactic cannot be used indefinitely as the average arsenic level of global concentrates rises inexorably. Further, smelters (often in urban locations) cannot be expected to deal with both ever-increasing arsenic in the feed and stricter restrictions on emissions and disposal. A rising “inventory” of primary copper deposits are already constrained from development by high arsenic concentrate. These deposits will need to be developed if future copper demand is to be met. An economic and technical solution to arsenic is needed. The gold industry may also face challenges in the use of cyanide, by far the dominant lixiviant used in gold and silver production. Public perception has driven restrictions on the use or transport of cyanide in some jurisdictions. History suggests that such pressure is only likely to increase. While there are several alternative lixiviants, none can yet match the utility and economics of cyanide.Such important issues will not be resolved by incremental change or new equipment items. They require development of new process technology - a tectonic event rather than an incremental change. It requires sustained effort (and expenditure) over decades and is very unlikely to result from “business as usual” for producers, suppliers or academics. Past major process developments were driven by a dire need for economic survival or by legislative change. What will drive the future changes?CITATION:Munro, P D, Pease, J D and Tuppurainen, J M I, 2017. Technology change by regulation – a cresting wave?, in Proceedings MetPlant 2017, pp 45–58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By K Ehrig, V Liebezeit, E Macmillan

The results from metallurgical test programs are used in feasibility studies for design of new plants and brownfield expansions, in long term mine plans, and to make decisions in an operating plant. There are many elements which contribute to a well-constructed test work program. Ultimately, understanding the accuracy and precision of the test work results is critical to ensuring good decision-making at various phases of a project.Every resource drilling and associated assaying program will have a quality assurance / quality control (QA/QC) component, however this often seems to be overlooked in metallurgical testing programs. The principles of “international standard” or “certified reference material” samples and replicate/duplicate testing can be applied to metallurgical programs, although there are metallurgical-specific considerations in both generating and analysing the data.This paper will describe the QA/QC program carried out within the Olympic Dam geometallurgy program. It will present results in the form of case studies from ten years of testing of replicates and bulk reference samples for industry-standard comminution tests as well as laboratory flotation and leaching tests. The Olympic Dam geometallurgy quality control program has enabled quantification of the precision of metallurgical testing and improved our understanding of the best possible modelling results given the underlying dataCITATION:Ehrig, K, Liebezeit, V and Macmillan, E, 2017. Metallurgical QA/QC – who needs it? The Olympic Dam experience, in Proceedings MetPlant 2017, pp 31–44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By B C. Povey, K Lagutin, M Mryasov, V Noll

The current Stoilensky magnetite concentrator comprises a three-stage crushing circuit followed by three stages of ball milling, grinding and concentration to produce a magnetite concentrate with 66.5% iron (Fe). The plant is built in four lines, three lines having four mills and one line with five mills, to treat 32 Mt/y of ore and produce 13.9 Mt/y of concentrate.NLMK, the owner, is Russia’s third largest steel maker and while the ore from the Stoilensky Mining and Beneficiation Plant (SGOK) provides the bulk of their supply, they still must buy ore from external sources at world prices. A decision was taken to expand the SGOK operation to supply all the NLMK concentrate, including the production of pellets.To commence the expansion, high pressure grinding rolls (HPGRs) were introduced as a fourth stage of crushing ahead of the first ball mill. This was a relatively low capital cost expansion and increased production by 12 to 15%, the cost being much less than an additional grinding line. The importance of this development was that earlier introductions of HPGRs in Russia had presented several problems so there was some reluctance to the initial concept. The even greater significance was that nearly every magnetite plant in Russia had a three-stage crushing circuit so the successful introduction of HPGRs was of interest to many operators.The design was developed by a team, consisting of Worley Parson, Mineralconsult and PiterGORproject (PGP), for the first four units to fit inside existing building structures. The first two units were commissioned in March 2016 and the next two units in May 2016, and production improved by over 12%. The design of the installation of the final four units is in progress and the installation is expected in late 2017.CITATION:Povey, B C, Noll, V, Lagutin, K and Mryasov, M, 2017. Introducing HPGR quaternary crushers in a Russian magnetite operation – challenges and solutions, in Proceedings MetPlant 2017, pp 84–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By J A. van Niekerk, J G. Jardine, J W. Olivier

The Runruno Gold Project is located on the island of Luzon, approximately 200 miles north of Manilla in the Philippines. The mine is an open cut operation and uses the proven BIOX® and carbon-in-leach (CIL) processes to recover gold, and the ASTER™ process for detoxification of the CIL residue prior to discharge to the Residue Storage Impoundment (RSI). Work to date has defined a mineral resource of 1.39 million ounces (Moz) of gold, and the operation will produce 96 700 oz of gold per annum over a mine life of 10.4 years. The BIOX circuit is designed to treat 140 000 t/y of concentrate with a design capacity of 404 t/d of concentrate at a design sulfide sulfur grade of 17% S2-.The Runruno BIOX Plant is the first application of the Outotec BIOX Generation III design principles, focussing on ease of operation and maintainability. During development and implementation, the project team focussed on identifying opportunities to optimise the capital efficiency while not compromising on the operability or overall efficiency of the process or the equipment. The BIOX plant also incorporates the latest developments in the design of the BIOX agitators for more efficient mixing and gas dispersion. This paper will discuss some of the critical aspects and decisions taken during the development and implementation of the BIOX Process at the Runruno Gold Project. The paper will highlight some of the factors affecting the commissioning process as well as the improvements seen through the introduction of the Generation III BIOX design principles. CITATION:van Niekerk, J A, Olivier, J W and Jardine, J G, 2017. Implementation of the BIOX® process at the Runruno Gold project, in Proceedings MetPlant 2017, pp 218–228 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By G R. Ballantyne, B Putland, I Lovatt, M Di Trento

The Tropicana Gold Mine, owned by AngloGold Ashanti Australia Ltd (70% owned and managed) and Independence Group NL (30%) is located 330 kilometres east-northeast of Kalgoorlie, Australia, in the newly developed Albany-Fraser Orogen. Following extensive feasibility studies, a high pressure grinding roll (HPGR)-ball milling circuit was selected based on the reduced power requirements and thus reduced operating expenses. The HPGR-ball mill circuit was estimated to require 75% of the energy of a standard semi-autogenous grinding (SAG) mill circuit. Even with an anticipated greater capital cost, the HPGR-ball mill circuit was found to give significantly better financial returns in all cases investigated in the feasibility study. A comparison between the specific energy requirements of the HPGR, crush and SAG based circuits (SABC) from the feasibility work was conducted and the HPGR circuit was found to be considerably more energy efficient. A survey was conducted and the efficiency of the HPGR was similar to both the overall circuit design and the HPGR laboratory results, reflecting the accuracy that is possible for design and operation of HPGR circuits.Between 2015 to 2016, the Tropicana circuit has achieved a 20% increase in throughput from 780 to 930 t/h, and this increase has been maintained in 2017. This improvement can largely be attributed to upgrades to material handling processes, increased HPGR speed and smaller HPGR screen apertures. The result of these changes has been to increase the ball mill capacity by increasing the breakage conducted by the HPGR.CITATION:Ballantyne, G R, Di Trento, M, Lovatt, I and Putland, B, 2017. Recent improvements in the milling circuit at Tropicana mine, in Proceedings MetPlant 2017, pp 73–83 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By I Grewal, M Lundt

Dense medium separation (DMS) is one of several preconcentration methods used for early waste rejection from run-of-mine ores at relatively coarse particle sizes prior to additional milling and beneficiation. DMS has been used extensively in the coal, diamonds, mineral sands, base metals and iron ore industries to produce either a final product or as a preconcentration step. Laboratory scale and pilot test work at the Met-Solve laboratory in Canada has demonstrated successful separation and upgrading of other minerals such as lead, zinc, copper and lithium based ores using DMS.This paper reviews historical dense media systems, results from the pilot-scale multi-stage DMS Separator “Condor” system, as well as production plants and associated laboratory heavy liquid separation (HLS) test work on various minerals. The mineral systems tested included a lithium bearing ore and a fluorspar ore. Other minerals were tested but are not reported in this paper.Pilot plant test work on a fluorspar ore showed that 41.6% of the mass could be rejected to the tailings stream while 95.3% of the CaF2 was recoverable to the product stream. On a spodumene sample that was tested, it was possible to reject 55% of the mass to tailings while recovering over 90% of the lithium.In recent market conditions and with the decreasing grades in existing ores, preconcentration should be a consideration to maximise the value of certain operations.CITATION:Lundt, M and Grewal, I, 2017. Dense media separation – a valuable process for preconcentration, in Proceedings MetPlant 2017, pp 122–130 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By L Hussey

Mt Keith concentrator treats low grade disseminated nickel sulfide ore supplied from the adjoining open pit mine. It is a traditional crushing, two-staged closed circuit grinding circuit (SAG & Ball Mills), followed by a complex split-size rougher, scavenger and cleaner flotation circuit. In 2016, 10.5 Mt was milled, at an average head grade of 0.54% Ni, yielding 35 000 nickel metal tonnes in concentrate.Historical analysis of the plant data indicated that of all the nickel lost in the fines rougher circuit tails stream, 25.6% was recoverable in an eight minute laboratory scale flotation test. These results implied that this fine nickel was readily available for recovery in the plant, either through operational improvements or additional flotation capacity. With operation optimisation ongoing, and capital within the business focused elsewhere, plant personnel were challenged to think differently about improving recovery.In 2012, a separate project to improve plant recovery when treating high talc ore was completed. Amongst other vessels, this project saw the installation of two 150 m3 Outotec Cells to the scavenger section of the fines rougher, middlings and scavengers (RMS 1) circuit. Since installation, the operation of these cells resulted in difficulties immediately upstream with instability in the scavenger cells. It was therefore decided that these cells would be better suited to treating the fines rougher circuit tails.The alterations required to divert these flows were minimal, with the capital project totalling $220 000.In the two years since installation, the fines rougher tailings nickel grade has dropped by 9.9%. The scavenger circuit has also seen a 2.8% reduction in tailings nickel grade, and instability issues were immediately resolved. This project serves as a lesson in how existing plant infrastructure may be better utilised to maximise recovery. Although this is especially applicable when capital constrained, such re-appropriation can be considered at any point to maximise return on existing assets. CITATION:Hussey, L, 2017. Repurposing flotation capacity at Mt Keith nickel concentrator, in Proceedings MetPlant 2017, pp 254–258 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By H Kurth, L Balzan

On-belt analysers have been used since the early 1980s in the coal sector to measure ash content in real time for diverting material on conveyors to remove waste, bypass beneficiation and allow suitable material to proceed to the wash plant for processing. Since 2008, a GEOSCAN-M elemental analyser has been used on an overland conveyor in South Africa to divert direct-shipping quality iron ore to bypass a jig plant. This paper focusses on recent evaluation work to determine the suitability of an on-belt analyser to upgrade the processing plant feed in a copper-gold operation.Copper-gold ore samples from New Gold’s New Afton Mine near Kamloops, BC, Canada were tested to assess measurement accuracy over short time increments. A two-minute measurement increment has been used in the minerals sector as a compromise between good measurement accuracy and a useful tonnage (haul truck equivalent size or smaller). At New Afton, this increment represents approximately 35 t of material. Segregation decisions are currently made after visual and sometimes analytical determination, at increments of approximately 500 t to designate material as ore or waste at the drawbell in the cave.Results of test work including the composition range and expected accuracies by element are shown. The operation, which is not mine constrained, was evaluating the potential for ore upgrading through waste and low grade increment diversion to upgrade ore quality feeding the mill. Prompt-gamma neutron activation analysis (PGNAA) was considered as the company recognised that it would measure through the full conveyed cross section continuously and produce multi-elemental measurements unaffected by particle size, dust, moisture content, layering and segregation, mineralogy and belt speed.GEOSCAN analyses over various analysis periods will be collected to identify variability in the conveyed material quality and used to generate tonnage-grade curves so that an optimal diversion (bulk sorting) tonnage increment can be determined. Measurement increment time can be customised to suit site requirements. CITATION:Kurth, H and Balzan, L, 2017. Assessing bulk sorting suitability at the New Afton mine, in Proceedings MetPlant 2017, pp 315–323 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By I Ritchie, A Johnston, D Yataco

Marcobre SAC (Marcobre) is developing the Mina Justa copper mine project, located in the Ica region of Peru. The Mina Justa IOCG orebody comprises of a sulfide mass overlain by an oxide cap with a sharp transitional zone between the sulfide and oxide masses. The primary target metal is copper, but there are minor amounts of gold and silver. The oxide will be treated by HPGR, crushing and vat leaching, whereas the sulfide will be treated by HPGR, milling and froth flotation. The processing selections are due to some unusual ore characteristics which have required relatively unconventional solutions.Vat leaching was chosen over heap leaching and other processes after detailed trade-off studies found it to be the most attractive, primarily due to the high acid consumption of the ore. The sulfide flotation produces a wide range of concentrate grades due to the complex nature of the mineralogy. The selection of HPGR circuits for both the oxide and sulfide ore is due to the extremely hard and competent nature of the deposit. These factors and others have contributed to a unique process selection for this resource.The selection process for the oxide and sulfide ores, and an overview of the technology, equipment selection and geometallurgy, will be discussed.CITATION:Johnston, A, Ritchie, I and Yataco, D, 2017. Process development for the Mina Justa project, in Proceedings MetPlant 2017, pp 207–217 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By P Radulovic, V Lawson, M Muller, J Wallace

The Mount Isa Copper Concentrator was commissioned in 1973. Since commissioning some significant upgrades have been undertaken such as: • the replacement of the rod mill/ball mill circuit with AG mills and the subsequent conversion of the AG mills to SAG Mills. • the introduction of columns as retreat cleaners in 1987, then reallocated as prefloat cleaners in 1994 and rougher cleaners in 1996.• the repurposing of some rougher capacity to preflotation roughing to remove carbonaceous pyrite and talc in 1994.• the introduction of a Jameson Cell for preflotation cleaning in 2000. • the expansion of the rougher and cleaner circuits in 2002 with the inclusion of 6 x 100 m3 Wemco cells to replace the capacity lost to preflotation and to increase residence time and improve recovery. In 2013 work commenced to replace the cleaner circuit after 40 years of operation. The new cleaner circuit, consisting of 3 x B5400/18 Jameson Cells, replaced the rougher cleaner columns, cleaners, recleaners and retreat Agitair banks and was commissioned in Sep 2015. The new cleaner circuit was configured as two cells in series producing the final concentrate and a cleaner scavenger cell to supplement the existing Wemco cleaner scavenger cells. The performance of the new circuit is discussed.CITATION:Lawson, V, Muller, M, Radulovic, P and Wallace, J, 2017. Mt Isa copper concentrator cleaner circuit redesign, in Proceedings MetPlant 2017, pp 279–287 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By A Gray

Physical separation features in almost every mineral processing circuit. The category encompasses a broad range of techniques and technologies including hydrocyclones, gravity concentration methods (including jigs, spirals, centrifugal concentrators, tables, heavy media separators) and thickeners, all of which make use of the inherent density differences between two mediums. It is also possible to include flotation, magnetic separation, and ore sorting in the physical separation category.However, opportunities for enhanced physical separation performance can now go beyond the common practice of optimising unit operations. Improved options exist for feed preparation ahead of the physical separation stage, enabling higher performance and lower cost outcomes for physical separation flow sheets and technologies.The use of new applications in breakage technologies combined with mineral liberation analysis to optimise liberation prior to the physical separation stage provides options for preconcentration and gangue rejection as well as better separation efficiency. The use of low cost gangue rejection and preconcentration can be an intermediate step between mining and processing that allows processing of lower cut-off grades from the mine whilst delivering higher grades to the mill.Optimising flow sheets and technology performance requires detailed understanding of particle size and shape distributions as well as liberation characteristics to suit the particular separation unit, combined with knowledge of the available technologies, their capabilities and the economic impact across the whole mine cycle.CITATION:Gray, A, 2017. The role of liberation in physical separation techniques, in Proceedings MetPlant 2017, pp 147–156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Jordaan Koos

This report looks at the application of Shaft Boring (SB) as an alternative methodology to conventional mechanized Drill and Blast (D&B), Shaft Sinking. Various Continuous Mechanized Shaft Sinking concepts, equipment and projects are also reviewed in this report. Their significance relates to designs and systems related to Shaft Boring. Shaft Boring is increasingly a method considered for the excavation of deep and increasingly large diameter shafts for mines in hard rock. Many methods have been used as an alternative for D&B Shaft Sinking.

Sep 1, 2017

By N Coplin

Australian Coal Association Research Program (ACARP) project C25073 was proposed by industry stakeholders seeking a potential solution that improves underground air quality and reduces operational costs associated with technology used to control diesel particulate emissions in the underground coal mining environment.The need to protect workers from diesel particulate matter (DPM) has lead the underground coal mining industry to install disposable filter systems on their vehicles. While the disposable filters are efficient at removing significant amounts of DPM, the following major issues have arisen:- high cost of operations; disposable filters cost $A250–300 each and need to be changed at least once per shift resulting in an estimated cost of up to $A164 M/a, in filters alone, to the NSW underground coal mining industry- improper installation, damaged seals and lack of installing a new filter when the old filter is removed; workers are still being exposed to excessive amounts of DPM.The ACARP project successfully demonstrated significant DPM emissions reduction comparable to the incumbent disposable technology on a proof-of-concept wall-flow diesel particulate filter (DPF) system, as well as satisfactory system robustness when assessed using an industry representative test cycle representing operations of a load haul dump (LHD) vehicle typical of that used by the Australian underground coal industry. It was noted in testing that the technology increased modal NO2 formation, but was compliant over typical operational duty cycles.One of the key benefits with the use of a wall-flow DPF system is its tamper-proof design, mitigating the risk of operating unfiltered diesel plant in poorly ventilated areas. Elimination of the need for continual replacement of disposable filters provides significant operational savings estimated to be up to 80 per cent of the incumbent technology.In addition to the above, the project also delivered a number of significant contributions to the knowledgebase of the Australian and international coal industry with regard to the characterisation of operations and control of emissions.CITATION:Coplin, N, 2017. Wall-flow type diesel particulate filter system to replace existing wet element filter systems used in typical LHDs in underground coal operations, in Proceedings Australian Mine Vent Conference 2017, pp 119–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By H W. Wu

The objective of this paper is to examine some modern forms of auxiliary ventilation fabric ducting with streamline design fittings and the efficiency of construction practices. The most dynamic form of auxiliary ventilation is a moveable fan and ducting, which is easy to install and uses light weight fabric. The porous nature of some ducting construction results in leakage and loss of efficiency. Flexible fabric ducting is primarily associated with metalliferous mining and industrial material quarrying. Some applications are found in coal in stone/rock development and with use of dust scrubbers.Forcing auxiliary ventilation systems employing circular fabric ducting have been examined. Leakage of air from ducting is affected by ducting material and construction methodology (such as welded or sewn), quality of installation, number of joints, total length, pressure differences between the inside and outside and diameter. The best ducting system with welded construction can have up to four times less leakage as compared with some systems with sewn construction. It is also evident that the sewn type ducting will deliver less air to working faces and require more fan power, hence higher operating costs to run when connected to the same fan.A case study has also been undertaken to compare predicted operating costs of auxiliary ventilation systems connecting various types of ventilation duct fittings. The study also assesses the technical importance of streamline design with low aerodynamic resistance to reduce the shock losses of the duct fittings. It was found that the system connected with streamline designed fittings is able to provide some power cost savings and deliver more air compared with the system fitted with conventional fitting pieces.Using a ventilation ducting system with a lower leakage and frictional characteristic represents a sound solution to new challenges faced by the industry for increasing demand for better quantities and quality of air delivered to working faces; this is due to higher production schedules and stricter mine health and safety regulations within the Australian mining industry.CITATION:Wu, H W and Gillies, A D S, 2017. A comparison of auxiliary ventilation systems and their predicted operational performances, in Proceedings Australian Mine Vent Conference 2017, pp 207–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By S Kundu, J Zanganeh, D Eschebach, B Moghtaderi

The concentrations of methane and coal dust vary from one location to another in underground coalmines. In the presence of an ignition source, such as static electricity, these mixtures can initiate explosions and consequently cause massive destruction. Research data can help in understanding the level of hazards and associated risk these flammable mixtures can produce. For instance, the level of peak explosion pressure and flame speed can be well understood from experimental and numerical research data. With this aim, methane–air mixtures and methane-coal dust-air mixtures were employed in a ducted spherical vessel. According to literature, the maximum value of peak explosion pressure can be obtained in vessels of spherical geometry when compared to vessels of other geometries. Thus the values of explosion parameters generated from spherical vessels can be incorporated in understanding the highest level of hazard that can occur in a real world scenario.In this study, the duct integrated with the vessel resembles any channel or pathway connected to a methane and/or coal dust rich area in the mine. Experimental investigations emphasise that the severity of explosion in the explosion zone transmits to the channel or pathway. The length of the channel or pathway also plays an important role on the values of explosion parameters. The greater the length of the channel or pathway, the higher the explosion pressure is and therefore the higher the destruction. Ignition energy and concentrations of methane and coal dust were varied in collecting experimental data. The data of explosion parameters thus obtained can be employed in addressing hazard mitigation strategies in coalmines.CITATION:Kundu, S, Zanganeh, J, Eschebach, D and Moghtaderi, B, 2017. Incorporating research data in addressing methane and coal dust fire, and explosion hazards in coalmines, in Proceedings Australian Mine Vent Conference 2017, pp 175–180 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017