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By Akerkar D. D, Dey M. L, Mathur S. B, Chowdhury S. K R

The extraction of gold and silver from chalcopyrite concentrates has been investigated. In view of the recent interest in non-cyanide leachants for gold and silver, one such alternative reagent, namely thiourea, has been employed in the present work. Precious metal leaching was attempted from received copper concentrates as well as pre-oxidised concentrates. Pre-oxidation of the concentrates was carried out by three different methods, namely roasting, pressure oxidation and biological oxidation. After pre-oxidation and leaching of the base metals, the leach residues were subjected to further leaching for precious metal extraction. The results obtained on the extraction of gold and silver from received concentrates as well as pre-oxidised concentrates are presented and the effectiveness of the three pre-oxidation routes employed is compared.

Jan 1, 1992

A massive cobalt-containing pyrite orebody occurs in banded albite-quartz-biotite rocks at Thackaringa, some 30 km SW of Broken Hill. Because of the world-wide shortage of cobalt during the late 1970s, serious consideration was given to the development of a suitable flow-sheet to recover the cobalt from this ore. Details of a pressure leaching process in which more than 90 per cent of the cobalt is extracted from a pyrite concentrate are presented.

Jan 1, 1983

By A J. Moore

The Australian Coal Association Research Program (ACARP) funded project, No C14057, entitled æEffect of Blasting on InfrastructureÆ, has been carried out with the objectives of providing methodologies for the assessment of the strength of infrastructure types and the establishment of responsible and realistic limits. Personnel from Melbourne, Newcastle and Swinburne Universities and Terrock Consulting Engineers conducted the project. Infrastructure types including: conveyors; power transmission towers; wooden power poles; electrical substations; pipelines, bridges; public access roads and underground workings have been investigated by both field studies and structural analysis. Railways, underground telecom cables, dams and industrial buildings have been reviewed using general structural analysis. This paper has been prepared for the mining industry to provide a progress report on the project.

Jan 1, 2007

By W J. Rankin

A study was carried out to compare the environmental impacts of a number of process routes for lead and zinc metal production from sulphide ores using Life Cycle Assessment methodology and based on average industry data derived from the literature. The processes investigated were:blast furnace production of lead; Imperial Smelting Process for lead and zinc production; and electrowinning of zinc with the mining and mineral processing stages common to all three routes. The effect of a number of process variables, namely ore grade, fuel source for electricity generation and efficiency of generation, on the environmental impacts was also examined. The environmental impact categories considered in the study were:total (or full cycle) energy consumption; Global Warming Potential (GWP); and Acidification Potential (AP). The results of the study show that when produced separately, zinc production is more than twice as energy intensive as lead production (viz 48 and 20 MJ/kg respectively), however when produced jointly by the Imperial Smelting process, the energy intensity of the two metals is not all that dissimilar (viz 36 and 32 MJ/kg respectively). The metal production and refining stage was found to make the greatest contribution to the overall environmental impacts for all three processes. The study also highlighted the importance of taking a life cycle approach when comparing the environmental impacts of different processes.

Jan 1, 2002

By J Finlay, P Betts, D Milton, H Williams

The aim of this paper is to present an innovative method to help delineate potential target volumes for haematite-goethite mineralisation as opposed to more magnetic ores. This is achieved through interpretation and modelling (2.5D and 3D inversions) of ground magnetics and gravity surveys over the Koolanooka South prospect in Western Australia. The targets are assumed to be dense and weakly magnetic and hosted within banded iron formation (BIF) horizons. Geophysical interpretation (2D map) was performed using a variety of processed magnetic and gravity images (Betts et al, 2007) to determine the distribution of lithologies, to understand the structural architecture and to map out any anomalous areas of excess density (possibly indicating goethite alteration). The created geological map is used to build geological cross-sections (geometrically consistent) that were modelled (in 2.5 D) against both potential field datasets. The crosssections are consequently used as the framework to build a 3D geological model. The model defines 3D volumes of rocks including several BIF horizons. The distribution of densities and magnetic susceptibilities of the BIFs is inverted within the GOCAD«-VPmg environment to reduce the misfit between the response of the model and the observed gravity and magnetics. By combining the results of both petrophysical property distribution it is possible to map out (using classical GIS type queries in 3D) volumes of higher density and lower magnetic susceptibility.

Jan 1, 2009

By Gardner H. J, Wadsley m. W

Bauxite from the Weipa and Andoom (North Queensland) deposits was treated to provide a low-iron raw material for high- alumina refractories or aluminium chloride manufacture. The operation involved passing crushed, calcined bauxite continuously through a single laboratory shaft furnace. Consecutive sulfidation and chlorination of the iron minerals within the furnace resulted in a beneficiate containing less than 2% (wt.) Fe203 and by-product ferric chloride con- taining only traces of aluminium.

Jan 1, 1979

By D Shuen, R Sales, D La Rosa

Semi-autogenous grinding (SAG) mill control is complex and depends on many dynamic process variables. Good control strategies ensure that a mill is operating as close to optimal as possible, resulting in significant economic benefits to an operation. Pueblo Viejo, a gold mine in the Dominican Republic, has been actively improving their control strategies since start-up in 2012, and one of these initiatives was to install an acoustic monitoring system on the SAG mill. The data from the system is used to optimise the mill’s performance by limiting the time the mill is either running too quiet or too loud. The lower limit is an indication that the charge in the mill is too high for efficient breakage or that the mill speed is too low and grinding media are not striking the toe of the charge. Conversely, when the acoustic emissions from the mill are too high, this can indicate that the balls are striking above the toe of the charge, resulting in inefficient grinding and excessive liner and lifter wear. Adjusting mill operating conditions to keep acoustic emissions in the ‘sweet spot’ between these limits results in more efficient grinding.Pueblo Viejo installed a Metso SmartEar™ to monitor the acoustic emissions of their SAG mill in January 2013. This system has been installed on many mills around the world and is specifically designed for optimising SAG mill control. One system output is the impact counter which measures steel-on-steel impacts on the mill shell. The impact counter uses both frequency and time domain analysis to approximate the number of ball impacts per minute. This method of analysis excludes parts of the sound signal not associated with steel-on-steel impacts and gives an accurate measure of this critical control parameter. After the acoustic system was installed, Pueblo Viejo collected data to determine the upper and lower limits for the impact count variable. The live data is available to the mill operators and it is used as one of the key operating variables to control the mill.Through continuous improvement and the use of advanced technologies like SmartEar™, Pueblo Viejo are improving the control and operation of their SAG mill, resulting in reduced liner wear, more efficient mill performance and optimised energy consumption. This paper discusses the installation of the system, and the measureable benefits obtained by using acoustic monitoring to control their SAG mill.CITATION:Shuen, D, Sales, R, Wortley, M and La Rosa, D, 2014. The benefits of using SmartEar™at Pueblo Viejo, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 297–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By G Sparrow

The Murray Basin is being heralded as the next major mineral sands province in Australia. Already exploration programs have delineated extensive commercial deposits and several companies are progressing with plans to produce zircon, rutile and ilmenite in the Basin. As these deposits are developed consideration will need to be given to several key issues of the Murray Darling Basin; the availability of fresh water and management of salinity in the area being two of them. In this paper ideas being developed in CSIRO that link the processing of mineral sands with the salinity problem in the Basin are presented. The proposal presented here is to process saline water to produce industrial minerals with large volume applications and to produce value-added products from the mineral sands in the Basin using reagents produced from the saline waters. Processes to produce titania pigment and zirconia consume chlorine, caustic soda, soda ash and hydrochloric acid, all derivatives of salt (sodium chloride). There may be a good economic incentive if these processing plants were located in the close vicinity of each other.

Jan 1, 2001

The Department of Conservation (DOC) manages public conservation land throughout New Zealand in terms of section 6 of the Conservation Act 1987. In brief, this requires DOC to manage the natural and historic resources of the land; promote the benefits of conservation to present and future generations; provide information about conservation; to foster recreation on the land; and allow for its use for tourism.   Locally the department's Tauranga Area Office manages approximately 60 000 hectares of Conservation Park (known as the Kaimai-Mamaku Forest Park) which includes early gold mining relics and former bush tramways associated with the logging and the mining industries. The Department has recently developed the Kaimai Heritage Plan which seeks to restore some of the relics and encourage involvement by the local communities in the restoration and interpretation of their history in the hills. It provides a unique opportunity for the Department to help bring alive for New Zealanders an important, and often overlooked, part of our history as a nation in a stunning natural setting.   The purpose of this presentation is to: +        display the endeavour and ingenuity of the early miners and loggers, the relics of those industries and the dramatic environment in which they worked; +        identify the linkages between those early industries and gold mining today; and +        promote a co-operative approach to heritage and recreation management involving all facets of the community.

Jan 1, 2006

Strong markets for metals and energy over the past five years have supported equity and debt market funding to enable a new group of mining juniors to emerge in control of economic resources, some in regions with high investment risk. As companies drive these projects to development, production and positive operating cash flow, their Boards and CEOs are confronting important questions:Having achieved initial success, what is our longer term purpose as a company? Does the purpose originally described in the Initial Public Offering to raise equity remain wholly relevant? Given that purpose, how do we understand the available sets of opportunities and related risks? Should we be acquiring new assets or other companies, or developing the existing portfolio? What commodity sectors and geographies should we focus on? Or should we be conserving funds until asset prices or project costs provide greater assurance of value to shareholders? How do we translate that purpose into tangible goals that shape and direct the work of people in the organisation? How do we get the right work done in the face of high turnover and competition for capable staff? Drawing on the authorÆs career experience and on work undertaken by Heuris Partners, this paper provides a practical CEO framework for strategy development, organisation design and on planning the work of the business in the mining industry.

Jan 1, 2006

By Hebbard GJ

Vertical crater retreat mining is being used at Zinc Corporation, Limited and New Broken Hill Consolidated, Limited for pillar recovery between previously mined and filled stopes. In order to increase productivity in the older lead lode areas of the mine, particularly in the lower grade sections around the keel of the orebody, score form of longhole stoping was considered necessary.Due to poor ground conditions in the country rock surrounding the ore and the requirement to provide sane wall support during mining, primary VCR mining has been utilised in these areas.At Zinc Corporation, several stopes have thus far been mined by a hybrid longhole stripping - VCR method.

Jan 1, 1985

The Kyaukpahto gold deposit is located at latitude 23¦ 47Æ 55" N and longitude 95¦ 56Æ 35" E in the Kawlin-Wuntho district, Sagaing Division, Myanmar. Gold mineralisation is hosted in sandstone of the Male Formation (Eocene) and occurs as stockworks and disseminations. The high-grade gold mineralisation is locally concentrated in a breccia zone. The gold deposit is closely associated with a NNE-SSW trending fracture system that forms tensional open fractures. These tensional zones are thought to be directly related to the Sagiang transfer fault system that experienced several hundred kilometres of northward dextral movement during the post-Upper Miocene. Major sulfide minerals are pyrite and arsenopyrite with minor galena, chalcopyrite and sphalerite. Gold mineralisation is associated with intense silicification, sericitisation and argillic alteration. Primary Type I fluid inclusions in the quartz from the mineralised zone are 5 to 15 ¦m across and yield homogenisation temperatures of 239¦ - 310¦C and salinities of 1.2 - 10.9 wt per cent NaCl equivalent. Laser Raman spectroscopic analysis indicates the presence of CO2 and CH4 in Type II fluid inclusions. Sulfur isotope analysis of disseminated pyrite in the ore zone by the laser ablation method indicates d34S values from -5.48ë to +5.53ë. The geology, alteration, ore mineralogy, fluid inclusion microthermometry and sulfur isotope data of the Kyaukpahto deposit are consistent with an epithermal ore deposit model for the deposit. However, the presence of CO2-liquid bearing fluids and the detectable CH4 in the gaseous phase of the fluid inclusions conflict with a typical epithermal origin for the Kyaukpahto deposit. The host siltstone and mudstone sequence, trace element geochemistry, and the disseminated nature of sulfide and gold mineralisation are also common characteristics of a sedimentary rock-hosted gold deposit, and these features may indicate a Carlin-like affinity. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By A R. Cruden, M S. Egglseder

The formation of banded iron formation (BIF)-hosted high-grade iron ore deposits in the Hamersley Province, Australia has been debated for decades. Although a structural control on their formation is widely accepted, only the roles of large-scale structures (ie faults and folds) formed by brittle and ductile deformation have been considered to date. However, the deformation of multilayered sequences in the Hamersley Province (ie the Mount Bruce Supergroup), with their contrasting rheological behaviours, creates challenges for understanding the complex structural framework at regional to deposit scales, including the significance for mineralisation and orebody location.Our approach to understanding these complex relationships is based on an established principle of structural geology, which is to extrapolate microscale structures to deposit-scale structures and vice versa, supported by state-of-the-art 3D modelling techniques. Complexly deformed hand samples associated with the Mount Tom Price iron ore deposit (Hamersley Province, operated by Rio Tinto Ltd) have been analysed and visualised with 3D explicit (Move™, Midland Valley Ltd) and implicit modelling software packages (Leapfrog™, AranzGeo Ltd) and supported by microstructural investigations (optical and X-ray microscopy) and fieldwork.Our study shows that the deformation of BIFs in the central Hamersley Province is controlled by microscale chemical processes (ie dissolution precipitation creep) due to rheological differences between iron oxide and chert layers, contrasting fluid flow properties and layer thickness variations. These processes account for the removal of vast amounts of silica, its transportation by diffusion in the presence of a fluid and reprecipitation at low-pressure sites. Consequently, this structural framework was used by different upgrading fluids to form iron orebodies.CITATION:Egglseder, M S and Cruden, A R, 2015. Evolution of a structural framework for high-grade iron ore deposits, in Proceedings Iron Ore 2015, pp 255–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M Simpson

Greywackes of the greater Auckland Region (Brynderwyn Hills to Hamilton), when considered on a regional scale, have characteristic ranges of physical, mineralogical and other properties. Some properties (eg density, porosity, crushing resistance, clay index) generally cluster and correlate with the basement greywacke facies, regions and terranes recognised by geologists, and their diagenetic/metamorphic level. Other local factors, particularly variations in mineralogical composition, nature of matrix cement, grain size, and degree of weathering may produce aberrant properties. Some of these local variations, when extreme, have the potential to affect the aggregateÆs performance in roading or the concrete industries.   Smectite and the zeolite laumontite are the major deleterious minerals occurring in fresh greywacke rocks of the Auckland region, although weathered rocks may contain halloysite, an expanding member of the kaolin clay mineral group. These minerals, when found in abnormally high levels in greywackes cause expansion effects in the aggregate. Currently there are inconsistencies in the detailed correlation of shrinkage, clay index, clay mineral content and intrinsic expansion data that need further research to resolve them.  

Jan 1, 2007

By K Kinnunen

A strong correlation between the reduction degradation index (RDI) of production sinter and the titanium content of the sinter mix was identified at the Ruukki sintering plant between 2000 and 2004. The titanium distribution in different mineral phases was studied using samples from pot sintering tests. Titanium additions were made using two different materials: rutile and crushed titanium-bearing haematite pellets. While both titanium additions clearly increased the RDI, titanium seemed to favour secondary haematite. The study focused on the effect of titanium in haematite, because haematite is reduced to magnetite in the RDI test. During the haematite-magnetite reduction, reduction degradation was observed. To increase accuracy, the phenomenon was investigated first by sintering and then reducing synthetic minerals under controlled laboratory conditions at the University of Oulu. The effect of titanium oxide in solid solution in magnetite on the magnetite to haematite transformation rate was studied first in order to simulate the final stage of the sintering process. In other experiments, haematite samples doped with 0.5, 2.0 and 5.0 wt per cent titanium oxide were studied using thermogravimetry under a controlled gas atmosphere (CO/CO2/H2/N2). Sintered samples were reduced using the same gas composition as in the RDI test. Polished sections for optical microscopy and SEM-EDS analysis were prepared from both reduced and oxidised samples and unreduced sintered samples. The titanium oxide content of haematite had a clear effect on reduction degradation of the samples. Furthermore, increasing titanium oxide content in solid solution in magnetite radically accelerated the oxidation rate. Similar observations regarding the effects of titanium have been reported earlier, but this was the first time the effect of very small additions of titanium were shown to deteriorate blast furnace burden quality and a reason suggested behind the process.

Jan 1, 2007

A company tax rate based on profitability return, or as more commonly expressed, a resource rent taxation scheme has been intro- duced at various stages in the past by both Australian state and commonwealth governments. At present a number of overseas countries are applying this form of legislation to the taxing of sections of their mining industries. Within this study, ways in which this type of tax has been used are examined. The form in which the tax can be applied varies. 1. It can be selectively or universally applied. 2. The base on which economic return is calculated can be selected in a number of ways. 3. It can start operating only when high profit levels exist, or alternatively be the basis of a total taxation scheme. The implication for the Australian mining industry of the introduction of different types of resource rent taxation schemes is assessed within the context of previously enacted systems.

Jan 1, 1978

World class ore deposits can be defined commercially as deposits which contain metal concentrations in the upper quartile of resources size and/or grade, world wide, from which economic extraction can be undertaken, over a production period exceeding ten years, at a cost below the weighted average cost of cumulative production of the contained principal commodity of mines world wide.

Jan 1, 1993

By Keyte SG

Gravity methods of recovering alluvial gold are not very efficient at particle sizes below about 0.1mm. Whereas such gold may not have been economic to recover in the past, the same may not be true today. Centrifugal concentrators, like the Knudsen and Knelson bowls, are showing promise after an inauspicious start, at least in New Zealand. The large proportion of heavy mineral in many auriferous beach sands and the natural hydrophobicity of fine gold should make flotation an attractive contender for its recovery. The conventional mechanical flotation cell is effective, but roughing, scavenging and cleaning are necessary to achieve both high recovery and low mass yield. More problematic is the difficulty of maintaining coarse and dense sands in suspension. The air sparged hydrocyclone is effective at recovering fine gold from a fine Colarado River sand, but is not effective for the coarse and dense beach sands of New Zealand. The flotation column shows much promise for these sands, when recoveries of over 80% and mass yields of less than 1% can be achieved in a single pass. The froth separator of the USSR and flash flotation could also be worthy contenders. It is felt that flotation could be limited to naturally and artificially de-slimed concentrates.

Jan 1, 1990

By Ellis CG

The N.S.W. Department of Mineral Resources commissioned its first Mobile Gas Laboratory in 1973.Although originally intended for diesel exhaust analysis, it has been progress- ively made more suitable for mine air analysis. Currently there are two upgraded units in operation. These laboratories have been used at the scenes of four mine fires, two mine explosions and three recovery operations. The authors' experience jointly covers all of these incidents. In this paper they recount the role of the Mobile Laboratory in each incident - including the difficulties encountered - and trace the development of these units to their present state. Future improvements are foreshadowed, and some comments offered concerning the likely future role of these vehicles in mine Emergencies.

Jan 1, 1981

This paper describes the programing and specification requirements which affected the choice of excavation methods on the Melbourne Underground Rail Loop (M.U.R.L.). The various methods that were chosen are briefly described, and the three most used are compared in more detail. Excavation rates, cycle times and other statistics are compared for full face tunnel boring, full face drill and blast, and heading and bench using a road header excava- ting machine. The length of tunnel excavated is sufficient to enable meaningful statistics to be presented and the significant specifi- cation and geological factors are described to weight the statistics where necessary for purposes of comparison. Average tender prices are given for excavation and primary support to indicate the reimbursement sought by contractors to carry out this type of tunnelling.

Jan 1, 1981