Search Documents

By R Norris, M Dunne

Mining and mineral processing is expected by society and obliged by law to operate in an environmentally friendly fashion, minimising the impact on and avoiding damage to the environment. Substantial efforts by the industry, as well as by process and equipment designers have resulted in many innovative developments, which show that operating in an environmentally responsible manner can be achieved in a cost-effective way. This paper showcases five emerging equipment best practices in industry including installation examples. Flip-flow screening machines are proven worldwide in the dry classification of coal and other minerals, reducing the size of beneficiation plants whilst reducing energy, water demand and media consumption. They also allow the screening of wet/sticky materials not able to be sized using conventional screens. The belt press filter is a small fraction of the operating and capital cost of alternative dry tailings technologies. This gives operators who must dry their tailings a competitive advantage and makes such ægreenÆ operations much more sustainable. The filtercake is disposed with other plant rejects, eliminating the need for tailings dams to be constructed and thus also often increasing mine reserves. Mining applications include coal tailings, sand tailings, sinter plant waste and power station fly ash. Screen-scroll and vibrating centrifuges are widely used in the coal, potash and salt industries to dewater the product to low surface moistures. Inclined plate Lamella separators are used for toxic water clarification and/or sludge thickening in many downstream metal industries with the underflow often dewatered in a belt filter press. Such low cost, high capacity thickeners could also be used instead of conventional thickeners at smaller mines. The simple and reliable continuous washing upward flow (CWUF) sand filters have been used for treatment of waste water from coal preparation plants and steel works as well as in the worldwide production of potable water. The filtered waste water from mining processes can then either be reused or discharged from site. Other installations include cleaning mine water to prevent the blocking of dust suppression spray nozzles.

Jan 1, 2006

This paper is written as a supplement to that of Edwards, Baker and Knight on "The Geology of the Wonthaggi Coalfield" 1, the West Area pit being in an early developmental stage at the time of their paper. The thin seams to the west of Dudley Basin 2 had beenknown for many years but it was not until 1935 that it became necessary to work them. The West Area Pit came into production as Dudley Area Pit approached exhaustion in 1937. From available information it was estimated that early work would be in a 36in. bottom seam. The present top seam was not included in the reserves, but it was to be extracted where it proved thick enough for economical working.THE SEAMSEdwards, Baker and :Knight (1944) had insufficient information to correlate positively the West Area seams with those in the Dudley Basin. Their opinion was, however, that they were a westerly extension of the Bottom Seam. Since then the driving of the present north-east heading towards No. 4 Bench McBride Tunnel has established that the West Area seams are those worked as Bottom Seam in the Dudley Basin. West Area Top Seam is a seam that occurred above the Bottom Seam in the Dudley Basin. Only sporadic attempts have been made to work it in Central Area, because 30in. was considered an economic minimum height until recent times. This seam should not be confused with Top Seam, Dudley Basin, which lies some 300ft. above the bottom seam measures and except in isolated areas over deeper workings has been eroded away in West Area.

Jan 1, 1953

By R Norris, M Dunne

Substantial efforts by the industry, as well as by process and equipment designers, have resulted in many innovative developments that provide cost effective reductions in water usage. This paper showcases four emerging best practices in industry including examples of recent installations. Belt press filters are a small fraction of the operating and capital cost of alternative ædryÆ tailings technologies. This gives operators who must ædryÆ their tailings a competitive advantage and makes such operations much more sustainable. The new generation of belt filter presses use less energy, produces lower cake moistures and better disposal stacking properties. The need for tailings storage facilities may be eliminated or in some cases high-grade tailings can be dewatered and sold as a low value product. Mining applications include sand tailings, sinter plant waste, coal tailings and power station fly ash. Flip-flow screening machines are proven worldwide in the dry classification of coal and other minerals, reducing the size of beneficiation plants, whilst reducing energy, water demand and media consumption. They also allow the screening of wet/sticky materials not able to be sized using conventional screens. Lamella separators are used for toxic water clarification and/or sludge thickening in many downstream metal industries with the underflow often dewatered in a belt filter press. Such low cost, high capacity thickeners could also be used instead of conventional thickeners at smaller mines. The simple and reliable continuous washing upward flow (CWUF) sand filters have been used for treatment of waste water from coal preparation plants and steel works as well as in the production of potable water. The filtered waste water from mining processes can then either be reused or discharged from site. Other installations include cleaning mine water to prevent the blocking of dust suppression spray nozzles.

Jan 1, 2006

By S Graskoski, S Craig, C Myburgh

Too often in mine planning, maximising revenue-generating material takes precedence over minimising costs. The ability to target both revenue and cost optimisation enables mine plans to fulfil corporate objectives of targeting maximal project net present value (NPV). The state of current mining costs and increasing government regulations in Australia are forcing many mine planners to pay closer attention to cost minimisation. Dumping waste material, which ultimately forms waste landforms, represents a large cost to mining operations. A general mine, with a waste to ore strip ration of 6:1, allocates approximately 32 per cent of total mining costs to waste haulage alone (Gregory, 2003).Most scheduling packages do not dynamically build economic or minimal cost dumps as part of the scheduling process. In most cases, waste dumps are built after a mining schedule has been defined. Automated software is now available which dynamically schedules the pit and waste dumps together. The overall shape of the waste dump is therefore dictated by minimum cost or minimum haulage hours.The purpose of this paper is to compare dynamic pit and waste schedules to traditional methods which apply haulage estimations after defining the mining schedule. This paper includes a case study on the large open pit operation at Tropicana Gold Mine, a joint venture between AngloGold Ashanti Australia Ltd (70 per cent) and Independence Group NL (30 per cent). The operation will focus on mining three large open pits over a 13-year mining life. A total of 397 Mt of waste is mined and directed to multiple destinations including waste dumps, the run-of-mine (ROM) pad and tailings storage facility (TSF) perimeter.Due to these complexities, management of the haulage fleet, especially during the critical period of operation readiness and start-up, is essential. Critical infrastructure such as the TSF and ROM pad will need to be built early and these areas, as well as the sequential development of the waste dump, will need to be developed within the constraints of structured mining fleet build-up.This paper investigates the influences of haulage estimation accuracy and compares traditional approaches for waste planning to automated approaches using EVORELUTIONÖ.CITATION:Graskoski, S, Craig, S and Myburgh, C, 2013. Dynamic pit and waste dump schedule optimisation at Tropicana Gold Mine, in Proceedings World Gold 2013 , pp 121-128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

The current genesis of pisolites and channel iron deposits (CID) has been defined in a way that presents CID as unique in the world. The published material on detrital pisolites mostly details the West Australian CID; most other global occurrences of iron-rich pisolites would seem to have an in situ genesis. An alternate theory for the origin of the Hamersley CID is suggested, involving an older greensand protore derived from volcanic ash and deposited on a glaciated Hamersley surface. This paper presents the author's observations, sampling and mapping after several years study and exploration for pisolites and CID in WA and in some locations overseas. It is not what one would call scientifically complete, and possibly asks more questions than it answers, but it is presented as a point for discussion.

Jan 1, 2009

By R M. Arellano, D M. W Harney, M Makhuvha

Mineral resource and ore reserve estimates are founded on two sources of data: tonnage and grade. The tonnage is a product of volume and density; both of which are estimates. Density impacts numerous operational factors, which include, but are not limited to, mine design, mine planning, equipment selection and operational performance. Hence, density is a significant parameter and its determination requires similar care as the measurement of grade. Selecting an appropriate method to determine density, and ensuring its rigorous application, thus reduces risk and can improve operational performance, which in turn increases profit margin.Different Anglo American sites use a variety of practices and protocols to determine density, which is highly dependent on the physical characteristics of the orebody, local conditions and historical practices. Also, individual sites sometimes execute the same method in a slightly different way, which may also affect the outcome of the measurements. In order to gain a better understanding of how density is determined at Anglo American projects and operations, a review of these techniques was undertaken. The objective of the study was to identify and share good practices across the company, as well as to look for improvement opportunities, where applicable. Ten different methods of measuring density, applied to nine different commodities, were identified and described. An additional technique was recently developed by Anglo American Technical Solutions. The core pycnometer is a large gas displacement pycnometer capable of measuring density at high accuracy on full pieces of intact core.This paper provides an overview of methods used to determine density within the Anglo American Group, including quality control and quality assurance aspects. It is not the purpose of this paper to identify a preferred method, but to highlight the importance of choosing the best suited practice for a project or mine site. In addition, a case study comparing two different density determination methods applied to the same rock samples from the Los Bronces Copper mine was undertaken and the results of that study are presented here.Selecting the most appropriate method to determine density and comparing results from two or more techniques against each other, together with other suitable quality control procedures, is considered to be of utmost importance for all mining operations and exploration projects.CITATION:Makhuvha, M, Arellano, R M and Harney, D M W, 2014. Determination of bulk density in Anglo American plc, methods and impacts, with a case study from Los Bronces Mine, in Proceedings Ninth International Mining Geology Conference 2014 , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By B Putland, I Lovatt, D Schwann, A Cervillin

The Mount Carlton project in Queensland's North East sits on a high-sulphidation epithermal style deposit rich in gold, copper and silver. Mt Carlton is an open pit mining operation with ore processed using a primary crusher, single stage SAG mill and flotation to produce a concentrate for sale. Orway Mineral Consultants (OMC) was involved in the original design of the comminution circuit and the project was commissioned in late 2012, with first concentrate shipped in March 2013. When Evolution sought to optimise the project in 2015, OMC was invited to assist by undertaking a circuit review to identify opportunities for the optimisation. During 2016, the Mt Carlton site team implemented the optimisation strategies developed in conjunction with OMC. These included reconfiguring the SAG mill discharge arrangement, reducing the average ball diameter and allowing the mill to operate at higher speed and under more autogenous conditions. Cyclone operation was changed to constant pressure and the vortex finder size was decreased. The combined strategies improved energy efficiency and allowed higher SAG mill power utilisation. The additional power has been used to increase throughput by 2.4 per cent while achieving a 27µm reduction in product size (P80) to gain downstream recovery improvements. The reduction in grind size has been achieved with only 6.8 per cent increase in specific energy consumption because of a 6.5 per cent increase in grinding efficiency. The circuit product size is also notably more consistent due to the improvements made to the cyclones, providing benefit to the downstream flotation circuit. A significant decrease in ball consumption was also gained, saving hundreds of thousands of dollars a year in operating cost.This paper will discuss the circuit design, start up and will detail the changes made during the optimisation and why these were successful.CITATION:Putland, B, Lovatt, I, Cervillin, A and Schwann, D, 2018. Mount Carlton comminution circuit design, start-up and optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 517–528 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By D Baas, D Bennett

This paper describes how Brisbane-based PanAust Limited develops process control strategies that are implemented at all operations and are used in functional descriptions for plant upgrades and new projects.The process control strategies are determined by operating management philosophies designed to maximise returns from the company’s assets.The approach is endorsed in the project planning and design phases to ensure facilities and equipment that form the major production assets are fit for purpose and capable of enabling the production managers and operators of the projects to maximise shareholder returns.PanAust’s process control approach has been to develop sets of process control standards which focus on two key areas. The first area covers hardware requirements and architecture, software objectives, control models and individual loop tuning methods. The second area defines control room layout, graphic standards and the alarm philosophy. The application of these standards in a new plant or upgrade decreases the time required to achieve design capacity and optimal performance.The PanAust process control strategy changes the operator’s role from one that controls a number of individual loops to one that sets the control objectives of the processing plant. To achieve optimal performance, all the process areas of the plant are analysed to identify opportunities to improve throughput, recovery and stability. Once a key opportunity is identified, a process control strategy is developed which defines the objective of the control, its functionality and how an operator will interact with it. After development of the control model the operators assist engineers to test and debug it. Once the model is robust, it can then be duplicated throughout the group and developed as a group process control standard.CITATION:Baas, D, Bennett, D and Walker, P, 2014. Developing process control standards for optimal plant performance at PanAust Limited, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 325–334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

The following paper outlines the types of employment immediately available to graduates following their university degree, a discussion on mine manager requirements, mentions career advancement and time frames to achieve this as well as providing some key information regarding student vacation work. The author hopes to educate present graduates, as well as inform students of characteristics to develop the most opportunities in life.

Jan 1, 2006

By M A. Rhamdhani, K Avarmaa, A Putera, J Chen, G Brooks

Silicon-based photovoltaic cells are currently the most dominant types applied to convert solar energy to electricity. In solar-grade silicon (SG-Si), the control of boron (B) and phosphorus (P) is very critical. Generally, these elements are difficult to remove into acceptable sub-ppm levels from lower grade Si. This study investigates slag treatment as a process for Si refining, focusing on the behaviour of P and B. The experiments were conducted by equilibrating Si-B-P alloys with 43 wt per cent SiO2 – 47 wt per cent CaO – 10 wt per cent Al2O3 slag under inert atmosphere at 1500°C. Different crucible materials were used (Al2O3, SiO2 and MgO), which determined the primary saturation phase for the system and modified the final slag composition accordingly. The samples were equilibrated and analysed with microanalysis techniques (EPMA (electron probe microanalysis) and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry)). New standards were prepared and applied in the LA-ICP-MS analyses. Experimental results show that silver is essentially fully dissolved in silicon, as well as most phosphorus with LP ( = wt per cent P in slag/wt per cent P in Si) between 0.1–0.3. The distribution coefficient of boron was measured to be between 1 and 2. The crucible material used had an influence on the phase compositions and slight influence on the distribution coefficients of boron and phosphorus. The experimental results provided new accurate data when considering applicability of slag treatment as a technique for Si refining and Si PV cell recycling.

Jun 19, 2024

By G Stovpchenko, G Jianjun, L Medovar

Electroslag remelting (ESR) today and into the future, will still be the main process for producing high-quality ingots by suppressing segregation, not just refining chemical composition from impurities. This paper analyses state-of-the-art electroslag refining with a focus on ESR with consumable electrodes, and recent technology with liquid metal supply (ESR LM) in view of their refining abilities and development trends, taking into consideration that the size of the ingots required by industry continues to grow, and the composition of new materials sophisticates to withstand increasingly higher mechanical and temperature loads . The yield of suitable metal in large ingots produced by conventional casting is low due to problems of element segregation by height and crosssection. For example, conventional ingots for nuclear powerplant rotors today reach nearly 700 t in weight. Attempts to directly replace such giant ingots with big-diameter ESR ingots weighing approximately 400 t were also unsuccessful because of growing segregation. Modern ESR equipment and technologies produce 200–250 t of ingots of satisfactory quality, reaching 2.5 m in diameter, implementing the change of consumable electrodes during remelting to increase ingot length. Another way to mitigate segregation is to enlarge the smaller diameter ESR ingot by a 500– 800 mm coaxial layer to the desirable diameter by ESR in the current-supplying mould (CSM). Modelling and experiments prove that refining from impurities and non-metallic inclusions at ESR most effectively occurs at the slag bath and liquid metal pool interface because the ESR LM has provided the same desulfurisation. ESR’s special refining capabilities in CSM come from the much longer time of LM residence shown at titanium purification from hard-melting nitride inclusions that are unremovable in vacuum arc remelting (VAR) and electron beam melting (EBM). Implementation of ESR technologies in CSM, especially with LM supply, is prospective to produce heavy enlarged and hollow forging ingots with prevented development of segregation due to dividing cross-section and reducing overheat of solidifying metal.

Jun 19, 2024

By S Harris, A Bossilkov

The Kwinana (Western Australia) and Gladstone (Queensland) industrial areas are among the few dozens of heavy industrial areas globally that demonstrate significant levels of regional resource synergies. Such synergies are also referred to as æindustrial ecologyÆ or æindustrial symbiosisÆ. Fundamentally they involve the exchange of by-products or sharing of utilities between companies in close geographic proximity to achieve competitive advantage and environmental benefit. A concerted research effort is currently underway to foster greater realisation of regional resource synergies in minerals processing intensive regions, in Australia and internationally. This paper summarises current insights from the foundation research into engineering tools and technologies and enabling mechanisms for regional resource synergy developments. Regional resource synergy developments were reviewed for 16 international and two Australian regions. It was found that Kwinana and Gladstone compare favourably with the well-regarded international examples of regional synergy development. Given the fairly strong evidence that self-organisation is critical for regional synergy developments, an implementation model has been proposed that captures entry points for synergy developments at the level of platform (industry collaboration), process (developing synergy opportunities) and project (assessing and implementing specific synergies). It was also found that regional synergies have so far developed in the absence of specific methods for identification and screening of synergy opportunities. Moreover, very limited attention has been paid to the associated technological and engineering challenges. The current technical research effort therefore targets: the development of a toolset for the identification and development of potential synergy opportunities; and assessment of technology needs and opportunities for regional synergies involving water, energy and materials recovery and reuse.

Jan 1, 2006

By M Wen, J Gerit, C A. Pelletier, D Muggli

On-land waste rock dumps at BHP Billiton Base MetalsÆ Island Copper Mine (ICM) near the northern end of Vancouver Island, B.C. continue to discharge ARD. These waters, which amount to approximately five million cubic metres each year, are injected into a three-layer, meromictic pit lake for treatment. The top layer is brackish water, replenished by each yearÆs rainfall (amounting to nearly 2 m/year). This top layer of water must meet effluent permit limits for heavy metals. This water eventually exfiltrates through a æbeachÆ waste rock dump, which is 93 per cent submerged along the north shore of Rupert Inlet. The middle and bottom layers of the Pit Lake are saline and currently oxic (2 mg/L dissolved oxygen) and anoxic (0.03 mg/L dissolved oxygen), respectively. Spreading of a liquid fertilizer every ten days throughout the top layer results in plankton and bacterial blooms that scavenge zinc, copper and cadmium out of this layer eventually to become mineral sediment in the bottom of the pit lake. Adsorption on planktonic skeletons and mineral precipitates also scavenges these dissolved metals from the middle and bottom layers to form bottom sediment. Sulfate reduction has recently begun in the bottom sediments. Diagenetic processes in the bottom sediments will eventually transform most of the dissolved heavy metals into insoluble sulfides. Cycling of ferric iron between the sediment and the water column and back seems to contribute dramatically to the biogeochemical metal removal processes. This biogeochemical system serves to maintain the top-layer water well within permit limits for discharge to the environment.

Jan 1, 2003

By A Hatt

This paper presents a case study of characterisation work undertaken at a greenfield exploration project to provide engineering and OH&S inputs for the design of a ventilation system. The paper discusses how comprehensive early characterisation of the ambient surface and underground environment including aspects related to heat, dusts, strata gas, and geologic/mineralogical factors enables incorporation of the right ventilation and non-ventilation controls at a study level to mitigate the risks identified.

Oct 12, 2022

By C K. Boafo, J Visser

Obuasi Mine in Ghana, with more than 100 years of mining history, developed from a surface operation into a deep >2000 m underground gold mine. The challenge is to extract value from narrow veins left after extensive mining in the wider ore zones of the mine. Since the merger of AngloGold and Ashanti Goldfields in 2004 the mine strives to achieve optimum extraction through an integrated Mineral Resource management process from geological modelling, resource evaluation to mine design and scheduling. The shear hosted gold deposit displays complex secondary shears of variable thickness and continuity. There is an ongoing process of changes taking place in the way that geological modelling and resource estimation is done. Recent developments include the use of computerised systems that support the whole resource management chain from resource modelling to reserve optimisation. The change in thought and technology now allows for targeting narrow veins previously ignored in optimisation and mine design since moving into mechanised mining. The increased knowledge and confidence in the resource models now allows for flexibility in mine design, selection of mining method and scheduling and extraction of the reserves. The focus area for change is the way the orebody is evaluated and extraction designed. Since 2005 major changes were made to the process. This paper considers the historical approach of resource management. It looks at the individual process changes and qualifying the way ahead.

Jan 1, 2008

By I Lourel

In evaluating the installation of an in-pit crushing and conveying (IPCC) system for any mine, a number of options are available for each of the dig side, transport and dump side operations. Some of them are moreappropriate than others; given the pit arrangement, the material being handled and the rates at which it needs to be moved. This paper seeks to document the options that might be employed, and to rank them in terms of their applicability at any mine and their practicality overall, with a view to nominating those that would be most suitable for further study.

Jan 1, 2009

By W D. Rech, K W. Keskimaki

As an integral part of the conversion from rail haulage to conveyor haulage at Henderson, over six kilometres of drifting and several large complex openings were mined. The deepest of these areas was nearly two kilometres beneath the surface, bringing all of the challenges of rock stress and heat that come with mining at these depths. Though many mines operate at these depths, the development of the infrastructure necessary to support a 36 000 tonne per day caving operation brought some unique challenges to the development mining activity. The issues handled include: finding experienced staff for a æfast trackÆ development program; rock bursts and ground conditions; inflow of 50 degree centigrade water; acceleration of the project completion; large diameter raise boring and difficult muck handling.

Jan 1, 2000

By Green A. D M

The establishment of the Imperial Smelting Furnace at Sulphide Coporation Pty. Limited for the smelting of zinc and lead made it necessary to design and install sintering capacity to produce approximately 500 t.p.d. of zinc-lead sinter. The updraught sintering process installed is a recent development and the plant was designed with adequate flexibility and equipment to enable operating staff to investigate the process and achieve maximum production under optimum operating conditions.Sulphur dioxide gases from the sinter machine are passed to a contact acid plant for the manufacture of sulphuric acid.

Jan 1, 1964

By A M. Barrett, P J. Chapman

As filtering technology improves and there is an increased focus on environmental impacts, the concept of managing fine coal rejects by filtering, mixing with coarse rejects and dry stacking them is being considered more seriously. In Queensland, there appears to be a desire from regulators to move away from wet rejects facilities towards dry-stacked facilities, resulting in a change in the risk profile for the facility.A coalminer has a site with many constraints, including limited area that is not planned to be undermined and nearby rivers that are prone to flooding. The design of a dry-stacked facility that meets the operational requirements and environmental compliance criteria is challenging in subtropical climatic settings, where there is a need to consider wet seasons with high-volume, sustained rainfall events. The impact of the rainfall is multifaceted, requiring careful surface water management to separate clean and contact water, adequate foundation preparation to limit seepage to groundwater, management of stack stability given a potentially high phreatic surface and the avoidance of potential flood zones. These design constraints were compounded by a limited area available for rejects storage that would not be undermined.This paper presents a summary of the conceptual design of a dry rejects facility, including consideration of regulatory and client requirements, provision for expansion while also considering progressive rehabilitation, diversion of clean water as much as practicable during operations and siting constraints. A step-by-step concept is presented that addresses each constraint during the life of the facility.CITATION:Barrett, A M and Chapman, P J, 2015. Conceptual design of a dry-stacked coal rejects facility in a subtropical climate, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995