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By K Buda, W Staunton, M Hill, V Tjandrawan

One of the challenges facing the gold industry in the 21st century is the continuing need to identify new reserves of economically treatable ores. Discoveries of large, metallurgically simple orebodies are becoming increasingly rarer, forcing companies to investigate options for the processing of ores which may present recovery, economic and/or environmental issues, requiring innovative approaches to their treatment. Ores which contain naturally occurring carbonaceous material (æpreg-robbing oresÆ) are an example of one such ore type. NewmontÆs Jundee operation contains zones of carbonaceous ore within the oxidised orebody. A program consisting of detailed laboratory work and extensive plant trials has been undertaken to assess the options of the processing of this material. Laboratory tests demonstrated the advantage of carbon-in-leach (CIL) over direct cyanide leaching and carbon-in-pulp (CIP) for treatment of these ores. The laboratory program identified several factors which would enhance overall gold recoveries where preg-robbing ore was being processed, including: keeping preg-robbing ore separate from non-graphitic ore; maximising gravity recovery; and ensuring the plant operates in æpureÆ CIL mode, ie no leaching prior to first adsorption tank. Several plant trials were undertaken to assess the economic sustainability of treating moderate preg-robbing ores through a modified gravity/leach/adsorption circuit. Results indicated that where good operational control of the circuit was maintained to ensure high gravity recovery, minimal leaching prior to carbon contact, and maintenance of good, active carbon inventory, then acceptable and sustainable overall gold recoveries could be obtained. Using these relatively simple plant modifications potentially allows a plant to treat ores with preg-robbing index (PRI) values up to one. When PRI values rise to 1.3 - 1.6, leach recoveries can drop from >85 per cent to

Jan 1, 2007

By S N. Nyoni, K C. Corin, C T. O’Connor

Considering future water scenarios, as influenced by the increasing scarcity of water and the move towards sustainable process engineering etc, the closed water circuit becomes an important point of study in metallurgical operations, such as in milling and flotation. However, a deterrent in the use of recycled process water is often a lack of understanding of the effects of the accumulation of dissolved ions and other process chemicals. Recovery of the valuable minerals may be impacted by the concomitant complex mineral-pulp chemistry interactions. Literature indicates that these interactions are not necessarily antagonistic to process outcomes. Wet milling using steel media results in the dissolution of Fe from the media, the rate of which is dependent, inter alia, on the type of media and the chemical conditions of the aqueous environment in the mill. The pulp-phase interactions of dissolved ions with sulfide minerals may result in significant changes to the chemical conditions in the mill, which may subsequently impact negatively on the flotation recoveries. To understand the effect of these interactions in the context of the processing of sulfide minerals, this study seeks to consider the effect of three factors, viz mineral type – pyrite (Py) and galena (Gn) -, milling media of different compositions – forged steel (FS), 21 per cent high chrome and ceramic media -, and water chemistry, viz, deionised water (DI) and synthetic plant water (SPW). Ceramic media and galena are used for the respective control cases where the milling media and sulfide mineral contribute no Fe species. Using DI as a control case, a high ionic strength case is used to mimic the changes in water chemistry for a closed water circuit. Batch flotation tests are used as a diagnostic tool to determine the effects of these media-water-mineral interactions to investigate correlations between the chemical reactions occurring and chemical species present during the milling process and the ultimate flotation performance.

Aug 24, 2022

By Y Wu, F-J Ping

Today, coal production accounts for about 65 per cent of the nationÆs gross energy in China. By the year 2010, the output of coal is planned to increase to 1.65 billion tonnes and by the year 2020 to 1.9 - 2.0 billion tonnes. To meet these energy needs the Chinese coal industry is developing underground coal production on a massive scale. The new drive introduced by using direct torque control (DTC) is now proven technology for mine shaft hoisting. The drive offers unequalled speed and torque control performance as well as a low impact on the supply network by controlling the power factor to unity with a minimum of harmonics distortion.

Jan 1, 2005

Mine haul road design at Bougainville Copper Limited has undergone significant changes since mine start-up. Selection of 95 tonne trucks and the subsequent replacement by 155 tonne units is discussed, with particular reference to haul conditions within the mine. Changes to haul road design and construction practices are detailed which have lead to improved standards and tyre life. INTRODUCTION Bougainville Copper Limited operates one of the largest copper mines in the world at Panguna, Bougainville Island, in the North Solomons group of Papua New Guinea. The mine commenced commercial operation in April, 1972 and current planned production is 198 000 tonnes of material per day, of which 115 000 tonnes is ore averaging 0.46% copper. Annual total planned production is 72 000 000 tonnes to yield approximately 150 000 tonnes of copper with significant quantities of gold and silver. The mine operations workforce now consists of national employees up to General Foreman level.

Jan 1, 1982

The paper discusses the characteristics of Be-zymianny activity during the last 2500 years. Three periods of increased activity have been identified which are the eruptive cycles lasting for 100-400 yrs. The periods of high activity fall on the fol-lowing time intervals: 2400-1700 yrs ago, 1350-1000 yrs ago and from 1955 ixp to the present time. The 1955-1956 catastrophic eruption after a long period of repose (about 900-1000 yrs) opened a new cycle of activity of the volcano which is continuing to-day. Several decades are distinguished in activity which differ in character and intensity of eruptions.

Jan 1, 1990

By Smith IEM

Some samples from arc-type volcanic suites collected in northern New Zealand and southeastern Papua New Guinea show rare earth element (REE) and Y abundances which are enriched relative to the those typical of their respective associations. This enrichment appears to be the result of an alteration process which selectively mobilises the REE and re-precipitates them as REE-bearing minerals in veins and interstitial patches. The alteration is on a micron scale and is not detected in routine petrographic examination. The spectre of REE mobility in young apparently fresh rocks is important to igneous geochemists who use REE abundances to constrain petrogenetic models and may also be important because it indicates the operation of a natural REE enrichment process which could operate in the formation of economic REE deposits.

Jan 1, 1990

By H W. Scriba

The development and improvement of computer-based process simulation packages over the past 20 years has provided process engineers with a powerful tool to use in the design of complex metallurgical plants. The use of such modelling tools has enabled the design of process plants that minimise operating and capital costs whilst optimising plant efficiency and recovery. Almost every new project developed in the current market is underpinned by a simulation of the process. In line with engineering best practice this simulation should be based on laboratory/pilot plant test work results and sound assumptions. Any errors that are not identified in the development of the process simulation may have significant effects on the final design and operation of the processing plant. Developing a simulation of the process in a comprehensive, logical and auditable manner is thus essential in ensuring the simulation accurately represents the expected process plant behaviour. A methodology that ensures these requirements are met has been developed by SNC-Lavalin Australia and is described in this paper. The methodology includes the major review stages of data collection, model planning, model building and optimisation, model review, scenario testing and options development, and model reporting. All of these stages should incorporate comprehensive client interaction and review by a suitably qualified representative. In applying these methodologies SNC-Lavalin Australia ensures that the process simulation model developed can be confidently utilised in the design of the process plant, and in the estimation of operating and capital costs, whilst ensuring that engineering best practices are met.

Jan 1, 2008

By K Ehrig

Two irrefutable facts in geology and metallurgy are: ore deposits are comprised of variable mixtures of minerals which are systematically distributed throughout the deposit, and mineralogy exerts the primary control on metallurgical performance. If the distribution of process critical minerals can be quantified and mapped, then a logical assumption is that metallurgical performance can be predicted across the deposit.Olympic Dam is a +9 billion tonne Fe-oxide Cu-U-Au-Ag deposit which is hosted entirely within a magmatic-hydrothermal breccia complex consisting of over seventy ore and gangue minerals. Each has a unique set of metallurgical performance properties. Fortunately, 15 of the 70 minerals accounts for >98 per cent of the total rock mass.The mineral mapping journey commenced in the early drilling days shortly after the discovery of Olympic Dam in 1975. Geologists quickly recognised that the copper-iron sulphides had a predictable zoned distribution. However, geological models reflected the presence or relative abundances, not quantitative concentrations, of the minerals. This type of mineral mapping remained relatively unchanged for ~20 years and was of limited use outside of geology.Several things changed during the mid-1990s: assaying costs decreased significantly, instruments capable of automatically measuring mineralogy became readily available, the recognition of two quantifiable relationships at OD (ie mineralogy is a function of chemical composition (ie assays), and metallurgical performance is a function of assays, mineralogy, texture and process conditions. The linkage of metallurgical performance to mineralogy and mineralogy back to assays allows for every assayed sample in the resource model to be assigned mineral concentrations and metallurgical performance predictors. At Olympic Dam, block models (ie 3D maps) are routinely produced for 27 elements, density, 15 process critical minerals and greater than 50 metallurgical performance variables. These geometallurgy-enabled resource models are used for mine planning, process plant design and process optimisation studies. *This is an abstract only. No paper was prepared for this abstract.*

Sep 5, 2011

By Koppe JC, Strieder AJ

The Rivera Crystalline Island (RCI) is an erosional window of the intracontinental Parana Basin that outcrops in the Rivera Department, north of Uruguay. RCI is made up mainly by Precambrian granites, metasediments and granite-gneisses. This island is crosscut by a dextral transcurrent shear zone system, the Rivera Shear System (RSS). The bulk strain ellipsoid was defined by previous work and has allowed the evaluation of shear dynamics. The geometry of the shear system is made up of two shear directions: E-W (P-shear), which turn right to NW-SE direction (R-shear), leading to the development of extensional bends. The shear zone system was developed in brittle-ductile to brittle regimes, under temperature conditions compatible with greenschist facies metamorphism. The shear zones are marked by an intensive fracture cleavage development. Mylonites develop only in narrow, discontinuous higher strain zones. Internally, the shear zones are dominated by intrusive rocks, mainly granites, dacites and diorites. Hydrothermal alteration has been developed in several areas.The economic significance of RCI is given by several small gold deposits, which have been exploited since 1869. One major new gold mine is under development, the San Gregorio Gold Mine. This gold deposit is locally controlled by a dilatant site where R-shear turns right to P-shear. Mine lithologies were deeply altered by hydrothermal fluids in the dilatant structure. This work presents the lineament-structural analysis carried out to identify similar structural patterns in all RCI sites favourable to host other gold deposits. The exploration program also considered remote sensing, geology, geophysical and geochemical survey.

Jan 1, 1997

By W J. Botha

The Palaeoproterozoic Transvaal Supergroup in the northern Cape Province of South Africa hosts high grade (>60 per cent Fe) hematitic and specularitic iron and manganese mineralisation. The mineralisation is primarily exposed along the western margin or in the central part of a major interference fold structure known as the Maremane dome. The bulk of South AfricaÆs iron ore production is currently provided by two active mines, Kumba Resources megaton Sishen iron ore mine on the northern end of the dome, and the smaller Assmang Beeshoek mine on the southern closure. The undeveloped Sishen South deposit, which contains ~400 Mt of high-grade hematite ore, is located approximately 9 km towards the southwest of Postmasburg. It forms a linear extension of the Beeshoek mine and as such contains comparable laminated, breccia and conglomeratic iron mineralisation. The Transvaal Supergroup sediments were deposited in two distinct fault-controlled basins on the Archean Kaapvaal craton. Basement rocks in the western Griqualand West basin are formed by a carbonate platform sequence (Campbellrand Subgroup), which is overlain by a thick sequence of banded iron formation of the Asbesheuwels Subgroup. A major unconformity separates these rocks from the red-bed Gamagara Formation, which is correlated with the base of the Olifantshoek Supergroup. Diamictites and lavas of the Postmasburg Group have been thrust over these units from the west. The mineralisation process is related to regional scale supergene iron enrichment of Kuruman banded iron formations along the unconformity. During regional tectonism associated with the Kheis orogeny (2400 - 1700 Ma) the Maremane dome was uplifted, and the basal dolomite units thus exposed to erosion and karstification. The overlying banded iron formations collapsed into karst sinkhole structures where leaching of silica and enrichment of hematite occurred. Although the exact mechanism of the mineralising process remains unclear, karstification preserved components of the original concordant laminated and massive ores. These ores were subsequently eroded and deposited as conglomeratic and gritty ores down-dip of the Maremane dome in alluvial fan systems. A thin veneer of recent calcrete or Tertiary Kalahari clay beds masks the subsurface geology and most of the orebodies, thus ground geophysical gravity surveys proved excellent exploration tools to penetrate the surficial cover. These surveys were used extensively for delineation drilling and to deduce the subsurface geology and structural development of the area. Finally Sishen South orebodies were modelled with ModelVision software in an attempt to obtain an exploration template for the surrounding area.

Jan 1, 2005

By Kagl J, Publlier M, Nekitel S, Arumba J, Rangin C, Mosusu N

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

Based on a principle developed at a South African Mine, the CSIR developed a device with which the alignment of guide rails in mine shafts could be measured. Originally the technique could only be used to obtain guide misalignment values at the bunton sets. At the time this was considered adequate since it was assumed that guide realignment could only be done at the support points anyway. The technology was developed further and now it is possible to obtain æcontinuousÆ guide profiles from the measurements. Software was developed with which a guide realignment schedule can be drafted and the shape of the realigned guides can be predicted. A measuring system based on this technology is being used to conduct guide alignment measurements in shafts. The data is then analysed and a realignment schedule is recommended in consultation with the mine. Such a schedule may be prioritised so that the worst sections in the shaft are dealt with first. The measurement hardware and analysis software are described. Examples are presented that illustrate the principles and highlight measurement errors. A case study illustrates measurements recorded in a newly equipped shaft. A repeat measurement, 18 months later, shows the effect of recommended realignment as well as the change in guide alignment over this period.

Jan 1, 2005

By P Audet, D R. Mulligan, D Doley

This analysis attempts to reconcile existing ecological theories, rehabilitation planning goals and implementation constraints in the form of a rehabilitation paradigm that considers potential and pragmatic ecosystem transformation pathways. The framework prioritises multiple developmental scenarios for post-disturbed landscapes within a continuum of ecological outcomes. A feature of the framework is that ænovelÆ ecosystems and agro-ecosystems, having a range of commercial and societal values, are valid outcomes spanning the conceptual divide between the ecological functions of under-rehabilitated versus re-instated ænaturalÆ landscapes, especially in a changing environment. Landscape suitability analyses are considered to be fundamental to the incorporation of regional landscape and climate in the implementation of land rehabilitation and management strategies. Altogether, the paradigm could facilitate the identification of widely pertinent rehabilitation goals having direct implications at the regional scale of restoration ecology and acceptance of the need for ongoing commitment to the management of disturbed environments.CITATION:Audet, P, Doley, D and Mulligan, D R, 2012. Can ænovelÆ ecosystems offer suitable rehabilitation alternatives for post-mined landscapes?, in Proceedings Life-of-Mine 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

The mining, metallurgical, and petroleum industries can be viewed as financial or as social institutions or both. The differences between these two conceptions of their businesses will influence their environmental and social actions. During the next 10-20 years western industry will be subject to a drop in the growth of a more highly educated labour force and to the emergence of holistic economics, new national goals, and a new ecological perspective. The profitability of the mining industry may therefore be influenced by the human side of its business to a greater degree. The increas- ing human, social, and environmental responsibilities can be discharged by improving the miner's equip- ment; by learning to look at situations through the eyes of all those involved; by developing common `languages' which governments and the public can understand; and by mediating where feasible on the international scene.

Jan 1, 1978

By J Mavrogenes, C J. Spandler, S M. Eggins, K Worden

Major occurrences of platinum group minerals (PGM) are in crustally-contaminated, huge, layered igneous complexes (Bushveld and Stillwater) and gabbroic intrusions (Norilsk); relatively minor occurrences include arc-related æzoned Alaskan ultramaficsÆ. In terms of arc-related provenances, the recognition of alluvial PGM in river and beach deposits of southern South Island (Mitchell, 1995), in situ in the Longwoods (Cowden et al, 1990), and the ultramafic-mafic layered Greenhills Complex at Bluff (Spandler et al, 2000) raise the possibility that some economically-significant PGM deposits may exist in New Zealand. The Longwoods and Greenhills are in the Brook Street Terrane which is a remnant of a primitive intra-oceanic arc system of Late Permian-Early Triassic age. The Terrane comprises volcanogenic sequences containing plagioclase- and clinopyroxenephyric basalts, high-MgO ankaramite and dolerite dikes, trondhjemite plutons, and basaltic to andesitic volcaniclastic and sedimentary rocks. The cumulate complexes contain early-formed olivine- and clinopyroxene-rich ultramafic cumulates overlain by anorthite and hornblende-bearing gabbros. Primary (isoferroplatinum) and secondary (sperrylite) platinum group minerals are preserved in chrome-rich spinel pods in basal dunite of the Greenhills Complex. Saturation during early fractionation of primitive high-MgO magmas rather than magma mixing seems likely for the primary PGM. Together with correlative terranes in Queensland and New Caledonia, the Brooks Street Terrane is an exposed cross-section of an extensive Permo-Triassic island-arc system. Most parental magmas were primitive island-arc tholeiites, but other primary magma-types include high-MgO ankaramites and trondhjemites û the latter formed by partial melting of lower crustal clinopyroxene-rich cumulates and gabbros, respectively. The parental ankaramites fractionated to form mafic-ultramafic cumulates and primitive to evolved melts of high-Al basalt to andesite compositions (Takitimus). The Brook Street Terrane is an analogue for modern intra-oceanic islandarc systems and allows detailed study of subvolcanic arc processes.

Jan 1, 2005

By R Graber, R Johnson

North American steelmaking practices have evolved based on access to iron ore raw materials containing very low phosphorus contents, typically less than 0.025 per cent P. Cleveland-Cliffs managed Tilden iron ore operation produces iron ore pellets exceeding 0.030 per cent P, which by global standards would be considered low phosphorus, but has limited penetration in the North American iron ore market due to phosphorus content. Recently cathodoluminescence microscopy has augmented more standard ore characterisation techniques enhancing our understanding of the genetic history and process mineralogy of TildenÆs complex martite ore. This paper highlights the unique capabilities that cathodoluminescence microscopy provides for phosphorus mineral identification in fine-grained iron ores.

Jan 1, 2005

By Noble AC

Ore reserve reporting practices in the United States may be broken into four general categories as follows: ò Reserve reports, often of an unofficial and preliminary nature, which are made through the news media. These are often based on exploratory drilling or sampling results. ò Reserve reports made for the purpose of raising public funds by issuing securities on the stock market, or as part of other filings to the United States Securities and Exchange Commission. ò Reserve reports to obtain private funds from banks, financial institutions, or other investors. ò Reserve reports for internal use and planning by companies operating or evaluating mineral properties. This paper discusses current practices for each of these types of ore reserves reports and reviews recent changes which have affected those practices.

Jan 1, 1987

By B M. Moudgil

Atomic force microscopy (AFM) has become an important tool for understanding the nano- to molecular scale mechanisms predominant in multiphase systems. In flotation research, the use of AFM holds promise for unlocking and establishing fundamental mechanisms, ultimately leading to significant advances in process performance. From measuring and characterising surface forces, the structure of molecules at interfaces, and nanoscale features on flotation media, AFM is a powerful tool that has only begun to impact flotation research. Highlights of advances made in the utilisation of AFM for flotation research at the University of Florida are given with an emphasis on interpreting the mechanisms behind calcium activation in phosphate flotation and the impact of nanoscale asperities on collector-born surface hydrophobicity.

Jan 1, 2005

By R Simonato

It is now recognised that rotary sample division is by far the best laboratory tool for extracting subsamples from a lot of material. In terms of sampling theory, rotary division, by virtue of the fact that it can extract many increments from the lot during the division process, radically reduces the variance due to distributional heterogeneity in the sample being divided. There are a number of occasions in sample preparation when it is necessary to extract a subsample of a target mass. To do this with rotary dividers taking a fixed fraction of the starting mass is a tedious task. In response to this problem, a variable split sample divider has been designed and built for the mineral industry. This paper discusses the utility of the device and presents test data showing that the machine is capable of making accurate mass split while overcoming segregation in the material being divided.

Jan 1, 2008

By J Morton

There are many avenues for potential liability facing the Mining Industry today. Liability for breaches of environmental statutes such as the Resource Management Act 1991 and the Hazardous Substances and New Organisms Act 1997 include not only financial penalties but imprisonment and perhaps even more significantly will affect the reputation of the Industry. The potential for liability is not restricted to the employees that cause the actÆs to which liability attaches, but also potentially affects all the levels of management and even the company itself. There is also potential for liability through common law actions which can be utilised in cases of environmental harm. These should not be ignored by the Mining Industry. The Mining Industry must take a proactive approach to minimise exposure to potential environmental liability. This can be achieved by undertaking comprehensive environmental management initiatives and policies.

Jan 1, 2005