Search Documents

Botanical exploration has identified many plant species that naturally accumulate very high concentrations of elements, particularly heavy metals. The enormous potential applications of some of these species to remove metals from soil (phytoextraction) are slowly being realised. The discovery of hyperaccumulation has resulted in considerable research into applications for removing contaminants (phytoremediation) or more importantly, in the context of this discussion, for commercially æfarmingÆ metals (phytomining) from metal-bearing soils. Currently published phytoextraction models estimate Ni yields using Berkheya coddii (a South African nickelophyte) are approximately $US 750 ha-1, excluding the cost of processing. Research indicates that B. coddii will also accumulate significant amounts of Co, resulting in a considerable increase in the value of the crop. Modification of the substrate by acidification, fertilisation and/or chelation indicate fruitful avenues for improving this yield by increasing the extractability of the target element, elevating biomass production rates and/or rendering other contained heavy metals extractable. Plant uptake of more insoluble elements, such as Au, may be induced in many plant species using chemical compounds. These chelates applied to the soil, form soluble complexes with poorly soluble metals forcing them into the soil solution. Plants may then accumulate these metal complexes through transpiration. Research has achieved foliar Au concentrations of 78 mg kg-1 in Iberis intermedia, 56 mg kg-1 in Brassica juncea and 9 mg kg-1 in B. coddii (on a dry weight basis). Therefore in theory B. coddii could phytomine a soil containing modest concentrations of Ni, Co and Au to yield 116 kg Ni, 36 kg Co and over 6 oz Au ha-1 at a current value of $US 4000. Root crops have also shown promise in chelate assisted Au accumulation (eg 6.8 mg kg-1 in Beta vulgaris and 118.5 mg kg-1 in Raphanus sativus). Phytoextraction, in its varied applications, is rapidly coming of age as a technology having considerable potential for application in environmental science and the minerals industry. Phytotechnology employs unique plant biochemical behaviours in the rhizosphere, driven by the sunÆs energy, to seek out and concentrate low levels of heavy metals at very low cost.

Jan 1, 2002

By J Y. C Lo

The construction of two drainage tunnels and the associated subvertical drain system at the Po Shan area in Hong Kong was completed in December 2009. This project is the first of its kind to utilise drainage tunnels and a network of subvertical drains to regulate the groundwater table to enhance the long-term stability of the hillside of Po Shan area.The groundwater levels, monitored by preinstalled piezometers, once exhibited dramatic drops during drilling of the subvertical drains; however, have recovered from natural replenishment after effectively plugging of the drains. The level of groundwater drawdown is in line with the design function of the subvertical drains. In order to understand the groundwater flow pattern in the Po Shan area during and after construction and to set out operation schemes for the subvertical drain system so as to control the groundwater table in the Po Shan area, a post-construction review has been carried out to examine the behaviour of the drainage system and its impact on the surrounding subsurface groundwater flow.This paper presents a review of the groundwater monitoring data during and after the construction of the drainage tunnel system covering a period of over 3.5 years. A simplified conceptual hydrological model is developed, which has been verified by the monitoring data, to capture the key elements with regard to groundwater variations in different stages of the construction. The performance of the tunnel and subvertical drain system as revealed from these field measurements is discussed.

Mar 8, 2011

By A S. Derrington

In some parts of Australia, mine air cooling may not be needed until a depth of 1300 m below surface is reached. In other locations, it may be essential at a depth of only 300 m below surface. The reasons for these differences are multifaceted. This paper discusses the main factors and describes a simple method to assess whether or not mine air cooling will be required. The method uses a graphical relationship that considers depth below surface, geothermal gradient, surface climatic conditions and directness of the mine intake routes. This relationship has been developed, tested and refined over a period of more than ten years using data collected from most of Australia’s deeper metalliferous mines. The method provides a ‘first-pass’ indication of whether more detailed cooling studies may be needed. Perhaps more importantly, the method’s underpinning by benchmarking against other mines improves confidence in the assessment results. Like any empirical method, the context must be understood and this aspect is also discussedCITATION:Derrington, A S, 2014. Will your mine require cooling?, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 181–186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Y G. Anoman

This paper discusses the operating model within Endeavour Mining Corporation regarding the options of owner mining against contract mining. It’s based on the concept of ‘are we carrying out the most efficient mining’ regarding cost and performance. This question can only be answered through an extensive contract mining tender process and conducting a comprehensive comparison to evaluate the transition viability. Karma mine, located in Burkina Faso, is the subject of this paper. The Tender model included sales of equipment, parts and tooling associated with the traditional Load and Haul Schedule of Rates (SOR). The methodology focused on the structure of the tender process, which consists in the development of a SOR based on haulage profiles and mining schedule. This is a new Endeavour framework that allowed the bidders to compete on an even level. This was performed using a systemic analysis which encompassed all the elements involved in a transition such as the Human Resources (HR), taxes and customs implications, directs and non-direct costs (Finance and interest on assets, depreciation, insurance), contractor risk profiling. It was assessed against the normalised internal pricing tender-based. This paper gives an insight into how a West African mining operation addressed the sensitivities of the HR functions against the commercial aspects. This was one of the most successful transitions in West Africa and was carried out during the COVID crisis. The outcome of this project has created value by detailing a lesson learned model for both commercial and HR aspects. This discusses the commercial comparisons along with the internal model with the underlying HR functions as a risk factor that could have jeopardised the continuation of the operation. This resulted in a smooth transition with the additional cash flow generated by the sale of the parts and equipment turned Karma into a viable operation.

Jun 22, 2022

By S J. Tear, L D. Queen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Frieda River Project is located in the north-west of Papua New Guinea. The target commodities for a bulk mining operation are copper and gold associated with a large felsic porphyry system. The project comprises a series of deposits, with the Horse-Ivaal-Trukai (HIT) being the largest. It also includes the adjacent smaller Koki and Ekwai deposits.Previous resource estimates for the HIT were made using 14 separate mineralised domains based on structure, copper grades, lithology and alteration. H&S Consultants (H&SC) has revisited the deposit and concluded that a simpler methodology could be used for resource estimation without using wireframes as hard domain boundaries. This conclusion is based on reviewing all the available geological data combined with geological and resource experience of porphyry deposits.It is generally acknowledged that porphyry deposits form by diffusion of mineralising fluids through the host lithologies, meaning that sharp boundaries are unlikely unless these fluids encounter specific physical or chemical boundaries. It is important to prepare a comprehensive geological model prior to attempting resource estimation as it forms the framework for the estimates; however, not all geological features may be relevant to the distribution of mineralisation and there can be a tendency to overcomplicate the estimation process by using too many domains. Unless a hard boundary can be identified consistently and unequivocally, it is generally better not to use a boundary in that location.H&SC completed unconstrained models with no top-cutting using both a simple flat search ellipse and a steep search ellipse to generate global resource estimates reported within a predetermined pit shell at a 0.2 per cent copper cut-off. Both outcomes are within 10 per cent for the tonnes, contained copper tonnes and gold ounces compared to the constrained resource estimate. The slight differences are most likely due to the different search strategies, but also indicate the robustness of the unconstrained modelling approach.CITATION:Queen, L D and Tear, S J, 2015. The Frieda kiss – keeping it simple , in Proceedings PACRIM 2015 Congress, pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By D J. Bradshaw, E M. Wightman, B Newcombe

Flash flotation plays an integral role in many of the gold and sulfide mineral concentrators around the world, and yet despite this widespread use, very little information on this unit process is available in the published literature. For operations to maximise the performance of their flash flotation circuits, understanding how these cells operate, the nature of the particles they target and how to predict whether a flash flotation cell should be used on a specific ore type is of vital importance. This paper provides a summary of the key findings of a large flash flotation research project based in the operating environment of a refractory gold concentrator. The influence of key flotation performance criteria including gas dispersion, residence time and particle segregation within the cell will be discussed and recommendations for process improvements will be made throughout. The nature of the particles within the flash cell will be examined, as will the impact on the type of particles that are passed to downstream processes when the flash flotation cell is taken off-line. The development of a laboratory method to determine whether an ore is suitable to undergo the flash flotation process is also presented for its potential to aid in flow sheet development and optimisation for new ores.CITATION:Newcombe, B, Bradshaw, D J and Wightman, E M, 2012. Into the belly of the flash à Insights into the mechanisms at work within a flash flotation cell, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 163-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By P Ramsaywok

The use of saline water for mineral beneficiation in arid regions is general practice and also the case with Exxaro Namakwa Sands, situated on the west coast of South Africa. Although it is ‘cost effective’ to use sea water for mineral beneficiation, downstream process separation efficiencies may be negatively affected. This is more specific to surface dependent separation techniques such as electrostatic and high tension (HT) separation. If minimal fresh water is available then, proper washing is often neglected. Salt crystals can form on particle surfaces during the drying process before electrostatic separation.This paper describes a study that has been conducted to determine the effect of upfront salt water processing on downstream electrostatic/HT separation. The study indicated that minor quantities of salt can cause the separation efficiency to decrease substantially.

Oct 5, 2011

By J Seppelt

The Kanmantoo Copper Project is owned and operated by Hillgrove Resources Limited and is situated in the Adelaide Hills region in South Australia. Mining in the area has taken place off and on over the last 140 years to recover metal from both copper and lead-zinc ores. This paper focuses on the commissioning, ramp up and future outlook for the copper concentrator at the Kanmantoo Copper Project with major focus on issues encountered and operating performance achieved to date.CITATION:Seppelt, J, 2012. Commissioning of the Kanmantoo Copper Concentrator, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 127-136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By P M. Hetherington, F A. Pym, M P. Murphy, K E. Crook

Consultants in the mining industry have the opportunity to visit interesting deposits all over the world. Each deposit has its own set of challenges to face when it comes to defining and understanding the deposit geology and the economics to make it viable for extraction. Some of the challenges can include appropriate data capture, sampling techniques, structural characteristics, geochemistry, geophysics, lithology definition, and economic boundaries. It is essential that the practices used at each deposit (eg drilling, sampling, geological modelling, resource estimation etc) are documented and the results obtained are robust and defensible. The Competent Person is not always aware of instances where their resource estimation practices have not been substantiated. ‘You don’t know what you don’t know’ is a phrase frequently used during a mineral resource audit. Technical work to substantiate drilling, sampling, density, assaying, geological modelling and estimation processes is not always completed. Audited Competent Persons often comment: • ‘I was unaware that this was required.’ • ‘I have not had training in this area and do not know how to complete the checks required.’ • ‘This is how we’ve always done it.’ Examples of audits where it was found that geological practices were not substantiated are examined here. A discussion is included on why substantiation of these practices is important, and potential reasons as to why there are instances of unsubstantiated processes and practices are discussed.

Mar 22, 2022

By T Perera, B Fan, S Thang, T Hsia

Minerals are valuable resources and critical elements for a broad range of biological and technological applications, including technological developments to improve energy efficiency and the global movement to promote a low-carbon economy. However, in order to extract these critical metals, large amounts of waste and toxic chemicals are generated, as well as the use of high energy and large amounts of water consumption. Froth flotation is one of the most commonly used processes to separate and collect high-value minerals, but it still has some limitations, including low flotation efficiency performances using existing collectors and other reagents. Therefore, there is an urgent need to design and develop new metal-specific collectors to more efficiently separate and recover valuable minerals and to allow bulk water recovery from flocculated tailings. In this research, we propose to use our newly designed and synthesised novel collectors derived from a type of vitamin E (α-tocopherol), a relatively inexpensive and non-toxic natural molecule. As a potential collector-building block, α-tocopherol has a long hydrophobic carbon chain that facilitates the attachment to air bubbles during the froth flotation process. In addition, the phenol group of this molecule can be easily modified to incorporate various functional groups for targeting different types of minerals. Furthermore, α-tocopherol can be converted into a monomer for polymerisation by the reversible addition-fragmentation chain-transfer (RAFT) process, which can provide us with polymer based-collectors with high precision control of molecular weight and architecture. So far, small-scale qualitative experiments on α-tocopherol-based collectors have been performed with good results, which indicates the feasibility of these compounds as novel collectors for improved froth flotation processes.

Aug 24, 2022

By G J. Showers, P Botman, A G. Hunt

Iron Road Limited (Iron Road) is currently evaluating the feasibility of producing 21.5 Mt/a of high-grade (>66 per cent Fe) magnetite concentrate from a 3.7 Bt resource (JORC) located at Warramboo on the central Eyre Peninsula in South Australia. Bulk concentrate can be produced via a conventional grind and low-intensity magnetic separation flow sheet. Due to the comparatively coarse magnetite liberation size (106 µm), consideration was given to enhancing both the grind economics and coarser product sizing via gravity separation.This paper outlines the test work, flow sheet design and engineering design of a gravity beneficiation circuit (GBC) conducted by Mineral Technologies for Iron Road. The resulting circuit optimisation necessitated mass balance simulation by Iron Road’s SysCAD model to quantify the resulting changes in mill recirculation load. This included the determination of project-critical grinding power and energy requirements with and without the GBC installed into the primary ball mill classification circuit. The outcome of this work was the design of a GBC, including spirals and up-current classification, which led to a substantial reduction (33 per cent) in ball mill recirculating load and power requirements, together with a favourable coarsening of final product size due to the relatively coarser gravity concentrate. This has led to a significant reduction in project design capital and operating costs. A further benefit of this approach is increased recovery of (paramagnetic) hematite and lesser titano-hematite via gravity separation compared to an all-magnetic separation approach.CITATION:Hunt, A G, Showers, G J and Botman, P, 2015. Test work and design of a gravity circuit for Iron Road’s Central Eyre Iron Project, in Proceedings Iron Ore 2015, pp 139–142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Barnett J. C

The arid and semi-arid region of Western Australia occupies about two-thirds of the State equivalent to an area of about 1.8 million sqkm. Groundwater demand in this area has historically been linked to the pastoral andmining industries commencing with the gold discoveries in the Eastern Goldfields some 100 years ago. Substantial increases in demand have occurred in the past two decades initially as a result of nickel discoveriesin the early 1970's and more recently the rapid resurgence of the gold mining industry. Mineral exploration and development in the Great Sandy Desert at Telfer (gold) and Kintyre (uranium) and in the Great Victoria Desert at MulgaRocks (uranium) has also been accompanied by detailed groundwater investigations.

Jan 1, 1988

By T Gready

Stawell Gold Mines operates the Magdala underground mine in western Victoria, Australia. Several orebodies are extracted by longhole open stoping at a depth of 900 m below the town of Stawell. Some stopes are backfilled with cemented slurry rock fill (CSRF) to ensure stability, increase recovery of ore reserves, minimise dilution of ore grades, and add value to the project. StawellÆs simple CSRF system is described, including the novel equipment used to minimise capital costs. Design criteria, operating procedures, monitoring systems and results are discussed in detail. Practical aspects are considered, including lessons learnt about barricades, overbreak and segregation. The economics of CSRF are discussed, including capital costs, operating costs and the total cost per ounce of gold poured. Options for mining with and without CSRF are compared in terms of return on investment and net cash flows. Examples demonstrate the method used to calculate æbreak-evenÆ stope ore grades which determine whether or not CSRF will add value in different circumstances.

Jan 1, 2002

By G Haywood

This paper presents the evolution of the planning, scheduling and mining practices at the Yilgarn Star underground. The paper will concentrate on the principals of æjust in timeÆ and the impact of such practices on mine planning and scheduling and subsequent development and production. The principals of æjust in timeÆ were developed to minimise the impact of creep and time dependent failure of the ground in the ore and hangingwall zones. These zones are characterised by altered schistose material with inherent weak rock strengths compounded, at depth, by the maximum principal stress of the virgin stress field approaching the UCS of the rock mass. Yilgarn Star underground has and continues to develop the æjust in timeÆ methodology to ensure the continued viability of the mine. The mine continues to use longhole open stoping mining methods to ensure high levels of productivity with minimal dilution and at an acceptable cost of production.

Jan 1, 2002

By M Iglesias-Martínez

The potential for iron ore in the Central African Archean belts has received much less attention by comparison to their equivalents in other cratonic regions of West Africa, South Africa, Australia and Brazil. Historically, iron ore is known to occur in South Cameroon and North Gabon with significant iron ore deposits (eg Mbalam in Cameroon, Avima in the Republic of Congo, Minkébé, Bélinga and Boka-boka in Gabon), having been the subject of geological exploration programs carried out by government institutions and exploration companies. Although the presence of strong aeromagnetic anomalies, undeniably related to the presence of greenstone belt formations, has been recognised, this study is the first attempt to assess the potential of banded iron formations (BIF) in the Northern part of the Gabonese Republic in the region between Minvoul and Minkébé (>10.000 km2). Deep lateritic weathering, inaccessible equatorial rain forest and high operational costs are some of the reasons why only limited exploration has been undertaken in the area. This work aims to improve the geological knowledge and to highlight the potential for iron ore of the eastern margin of the Ntem Complex units dated between 3.3–2.7 Ga. Field work showed a series of mafic rocks (amphibolite, anorthosite and gabbro), schist and BIF (described as itabirites in neighbouring areas). Samples from Minvoul BIF showed an extensive and deep weathering to powdery hematite revealing the presence, in thin sections, of iron oxides including magnetite, hematite and martite, primary and secondary quartz, garnet, hornblende, anthophyllite, cummingtonite and epidote. Mineral assemblages and coarse grain size suggest a metamorphic grade ranging from medium to upper amphibolite facies. The existence of known economic iron ore deposits in neighbouring regions combined with an extensive weathering enrichment process are promising factors for potential iron ore discovery in this remote area.

Sep 18, 2023

By M Gao, V Lawson, W Valery

Changes in metal prices and mine output over recent years have required the Copper Concentrator of Mount Isa Mines to operate at annual tonnage rates varying from 4.0 million to 6.5 million tonnes. Several circuit combinations were operated during this period utilising up to two semi-autogenous grinding (SAG) mills and up to two ball mills. The aim was to maximise grinding efficiency and keep unit costs constant regardless of throughput rate. Measures to improve the SAG-ball mill unit operation were implemented with each circuit change. These included installation of a splitter to divert SAG Mill cyclone underflow back to the mill, increase SAG ball charge from four per cent v/v to eight per cent v/v, reduce in SAG top feed size and increase of ball mill grinding medium size. Modelling work and surveys led to a new design of the SAG liner profile from 60 rows of rail bar liners in a high-low arrangement to 40 rows of top hat liners in a high-high arrangement. An on-line SAG Mill feed sizing monitor was recently installed to improve grinding control.

Jan 1, 2000

In July 1997 Macraes Mining Company Limited deferred a 9 Mtpa expansion of the Macraes Gold Project because of the uncertainty of the future gold price and its impact on equity markets.  Additionally delays in the resource consenting process led to further uncertainty.   It has subsequently announced that a study has been commissioned to recommend a staged approach to development of its New Zealand business. The best economic development path will be determined to maximise returns to shareholders.

Jan 1, 1997

By D M R Stone

Failings di,posal presents many challenges at metal mines in Peru where the extreme relief yields very little useable land area. These challenges are amplified by other hazards such as the high seismic environment, high rainfall, and frequent debris torrents down the steep hillsides. As a result many mining operations have resorted to in-river disposal of mill tailings. This paper presents a case history of one underground metal mine located in the high Andes mountains of Peru where in-river disposal of tailings has been used for some 30 years. The paper outlines a comprehensive engineering study that was aimed at increasing the utilisation of tailings disposal underground. The scope of this study included modifications to the grinding and flotation circuits to produce a high sulphide and low sulphide tailings for underground and surface disposal respectively: mapping and cataloguing of abandoned stopes for hackfilling: modifications to the existing backfill system to improve icliahility and throughput, and a preliminary evaluation of alternatives Such as silicated and paste fills.

Jan 1, 1998

By C S. Kelsey, J R. Kelly

Australia is presently enjoying the fruits of a booming iron ore market. Expectations are that market strength will be supported in the short to medium term by increasing feedstock demands from steel mills, as world economies rebuild post-Covid-19. However, as cost and environmental pressures increase the longer-term market outlook will be dominated by product quality. The ‘flight to quality’ will place increasing demands on direct shipping ore miners as they compete to maintain their standing in the iron ore marketplace. China will progressively disengage from its dependence on Australian imports, leaving miners under increasing pressure to boost product quality and diversify outlets globally. Australia has vast deposits of low-grade magnetite ores located mainly in remote and arid regions of the continent. This paper proposes a dry grinding and magnetic separation process to produce premium concentrate grades from the low-grade ores, to assist in meeting future product quality demands. The premium grade concentrates could be either blended with lower quality direct shipping ores or marketed separately. The proposed dry concentration process involves the pairing of Vertical Roller Milling (VRM), a mature technology widely used in the cement industry, and Planar Magnetic Separation (PMS), a new methodology, which has been developed to the threshold of commercialisation by the private Australian company Cyclomag P/L. Two laboratory prototype planar magnetic separators with field strengths of 1800 gauss and 6000 gauss have been built and tested on a range of magnetite ore types over the past three years. In each case, following grinding to liberation sizes, a combination of roughing and cleaning operations has produced pellet grade concentrates. Vertical roller milling has competed successfully with conventional media milling in grinding cement clinker, limestone and blast furnace slags. A key advantage of dry VRM/PMS processing is its potential adaptability to stepwise modular development, which can minimise initial capital investment, while generating early revenue streams to cope with unpredictable market volatility.

Nov 8, 2021

By E Philippa, B Miller

Material characterisation, ore sequencing and process capability are commonly regarded as the key parameters to consider in designing and operating an effective pit to plant supply chain. Therefore, an understanding of rock mass properties is the starting point for controlling the presentation of problematic material to the ore handling plant and optimising process utilisation. There are different methodologies for characterising problematic material and ore handleability which exist across a spectrum of sophistication. At one end of this spectrum are simple indices built using first principles geology and at the other are complex algorithms developed using advanced analytical methods, machine learning and ore traceability. Regardless of the method, without an integrated process for careful management of problematic ore, material handling delays (ie blocked, bridged, blinded and buried events) will interrupt the stable flow of production. The ability of the ore control geologist to mitigate these delays is central to the ore handleability challenge. This paper describes a quick and easy solution that links the presentation of ore to the operating window at the crusher. This operating window is based on material characterisation, using the physical, textural and mechanical properties of the rock mass, and crusher performance. It also describes how a basic problematic ore index (POI) can be developed using ore tracking to the production face, petrographic studies of ore texture and mineralogy, and existing variables in the geological model. Finally, this paper will demonstrate that by coding the POI into the geological model for mine planning, together with performance monitoring through compliance to plan routines, material handling delays at the crusher can be reduced, unlocking significant resource value.

Mar 22, 2022