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By LaBrooy S. R, Ritchie I. M

Problems with the cyanidation of copper-gold ores Copper-rich gold ores are becoming increasingly important both within Australia and overseas (Dayton, 1982; Deng and Muir, 1994; Muir et al, 1993; Sceresini and Staunton, 1991; Solis, Hefter and May, 1995; Wall, Hornby and Sethi, 1987). In Australasia alone over 30 copper-gold deposits have been reported (Muir et al, 1993). Table 1 lists several of the deposits that have been processed. TABLE 1 Examples of copper-gold deposits in Australasia. Name

Jan 1, 1997

By Tran T

The kinetics of cementation of silver chloro-complexes from sodium chloride solutions onto copper and zinc was studied using rotating disc electrode system. The activation energies were found to be 10.8 and 30.5 k7/mole, in a 3M NaCl solution on copper and zinc discs, respectively. Higher dissolution factors were obtained on zinc disc, due to hydrogen evolution, whereas, copper dissolved close to the predicted values. Scanning electron microscope studies were conducted both on copper and zinc- cdiscs-to evaluate the deposit morphology and its effect on reaction kinetics. Two stage deposit growth was observed both on copper and zinc discs. Smooth, coherent initial deposit followed by tree-like secondary dendrites formed on copper, whereas, scattered bulbous initial deposit followed by porous dendrites was typical on zinc disc.

Jan 1, 1992

Computer modelling is being used to simulate rock fracture, caving and stress redistribution about longwall panels with increasing confidence. The models are being assessed against field monitoring and have significantly increased the understanding of caving mechanics within the overburden. This paper discusses the modelling approach and provides some examples of its application to overburden damage and induced hydraulic conductivity. Computer models used in this study simulate the fracture process in the geological units throughout the overburden. Analysis of the mining induced fracture patterns and in situ joint patterns allows an estimation of the hydraulic conductivity within the overburden. The cubic flow relationship has been used in the examples presented.

Jan 1, 2005

By Baguley PJ, Napier-Munn TJ

This paper presents preliminary resu]ts from field studies which were conducted to establish, among other things. the influence of medium viscosity on the partitioning behaviour of dense medium cyclones and drums in mineral applications, using frrrosilicon- ba_sed media. The medium vicoosit.y- was measured on-line, and partitioning behaviour was determined using ore sampling and density t r acers . The results demonstrate that viscosity is an important. operating variable, influencing ,eparat.ing density and efficiency under certain conditions. The implication is that metallurgical performance can be optimised by manipulating viscosity, either by appropriate selection of medium' characteristics or by automatic alarming and/or "ontroi using signals from the on- 1. i ne viscometer.

Jan 1, 1987

By Hendrix J. L, Nelson J. H

A study was conducted to examine how pretreatment of carbon-bearing gold ores with chlorine enhances gold recovery by cyanidation. It is hypothesized that metal species (including iron and copper) dissolved during chlorination adsorb on the carbon surface hindering the adsorption of dissolved gold. To test the hypothesis, samples of several sulfide minerals were subjected to reaction with sparged chlorine gas to determine which, if any, dissolve faster than gold under these conditions. Then, a synthetic carbonaceous refractory gold ore containing pyrite, chalcocite, activated carbon, and gold was subjected to gas sparging. The results of these experiments showed that chalcocite and arsenopyrite dissolve so that metal (copper and iron) is put into solution slightly faster than gold under the same chlorination conditions. Also, it was observed from the experiments that gold adsorbs on activated carbon during chlorination, but is replaced by copper and iron as the chlorination process dissolves more of the chalcocite and pyrite. The study concluded by investigating ferric chloride addition prior to chlorination to hinder gold adsorption on activated carbon.

Jan 1, 1991

By Laing W. P, Neill D. M, O&apos

The Reward polymetallic massive sulphide deposit occurs 35 km south of Charters Towers, adjacent to the Highway gold deposit (Fig. 1). It is hosted within rhyolitic lavas and interlayered volcaniclastics of the Cambro-Ordovician Mt Windsor Volcanics. Reward is a "blind" deposit discovered in 1987 after a long history of exploration by various companies in the area. The main pyrite dominant massive sulphide body occurs under 100m combined thickness of Tertiary fluviatile sediments overlying deeply weathered gossanous volcanics. The exploration case-history provides a striking example of how geological and structural models can be built up almost exclusively from drill information. Four different styles and ages of mineralisation are present: 1) volcanogenic Cu+Pb+Zn+Ag+Au massive sulphides of probable syngenetic origin; 2) remobilised Cu+Au in massive pyrite of metamorphic/deformational origin; 3) supergene and 4) oxide Cu+Au mineralisation of weathering origin. The massive pyrite body, containing chalcopyrite lenses, transects the stratigraphy and is inferred to contain in excess of 5 million tonnes. Overlying the primary mineralisation a supergene chalcocite rich zone contains a measured/indicated resource of 634,231 tonnes of 6.77% Cu which includes 287,000 tonnes of 1.32 g/t Au and 18 g/t Ag. In addition a measured/inferred oxide resource of 309,000 tonnes of 5 g/t Au and 27 g/t Ag overlies the supergene zone.

Jan 1, 1989

One distinctive feature of the global mining industry approaching the twenty-first century is the worldwide commitment of mining houses to large-scale projects in developing countries. One good example is BHP's development of the Escondida copper project in Chile. The Escondida orebody was discovered in 1981 and construction began in July 1988. Mining began in December 1990 at a design capacity of 320 000 tonnes of copper contained in concentrate. Out put has grown significantly and shortly Escondida will become the largest single copper mine in the world producing copper at the rate of 800 000 tonnes per annum, including 80 000 tonnes of copper metal. Escondida provides a case study of the development and growth of a large-scale mining operation in a developing country. Key elements have been innovative financing, the management of country risk, the recruitment of an excellent workforce, the use of advanced technologies and best practice in environmental management and community relations. Escondida is one of the global mining industry's success stories in the 1990s.

Jan 1, 1996

By S M. C Verryn

The amount of raw material used in the production of cement can be reduced by partially supplementing it by pozzolanic waste material without changing its properties negatively. This paper discusses results of an investigation using slag from the Pt industry, from the production of steel using Midrex processes as well as fly ashes from different coal power plants in South Africa. These are blended in a 20 per cent slag or fly ash to 80 per cent cement ratio. The properties of the mixtures depend on the phase composition, chemistry, grain size and the sources of the materials. The results are promising, but show variable behaviour depending on slag and cement composition. Compressive strength tests as well have heat flow curves showing the hydration behaviour, indicating that 20 per cent addition of slag or fly ash to ordinary Portland cement is viable. There is a large potential to use slag in cement mixtures and this study can be used to develop cements that will positively influence CO2 emissions and help to reduce large slag and fly ash stockpiles.

Jan 1, 2008

By Struthers M. A

The basement contact zone, a major fault structure underlying the copper orebodies at Mount Isa, has a significant influence on orebody extraction. The zone is comprised of a variety of weak, barren lithologies which often create very difficult mining conditions, contribute to stope dilution, and have an adverse effect on concentrator recoveries.The geological characteristics of the contact zone are described, and the importance of timely, accurate geological information emphasized.A variety of mine design strategies have been employed to reduce the impact of the contact zone on orebody extraction. Some of these are discussed, together with current trends in the southern areas where orebody geometry and hence mining methods change markedly.Recent developments in ground support techniques, such as cable dowel reinforcement, have significantly improved ground conditions in the contact zone. An example of the methods employed to improve knowledge of ground behaviour is presented. The trend towards increasing automation and larger equipment requires larger excavations; consequently ground support practices and knowledge of ground behaviour must continue to advance. Rock mechanics investigations will remain an essential part of the mine design process.

Jan 1, 1990

By Bradley AJ

Hamersley Iron Pty. Limited mines and pro cesses iron ore from two orebodies at Tom Price and Paraburdoo, situated in the North West of Western Australia. Conventional open pit mining methods are used at both sites in that material is drilled and blasted in benches, loaded by shovels and hauled to the Primary Crushers or dumped on waste or low grade material stockpiles. The present drilling fleet, consisting of eight high capacity Bucyrus Erie Rotary drills has evolved from an initial fleet of a large number of small percussion rigs. There are significant physical differences between the ore types encountered at both mines which nec- essitate the drilling of smaller diameter blast holes at Paraburdoo than those at Tom Price. The drilling practice at each site is dis- cussed, with examples of performance achieve- ments under varying drilling conditions.

Jan 1, 1978

By Bolton G. C

Experiments were conducted to access the feasibility of removing zinc from lead slag by sulfation or chlorination or both. Gaseous sulfation with sulfur dioxide and oxygen released only 50 per cent of zinc even under the most severe conditions. Sulfation with concentrated sulfuric acid by a fast-leach process released 95 per cent of zinc while pug-roasting released a maximum of 78 per cent of zinc. Chloridization with NaCi in the presence of sulfating gas released 50 per cent of zinc, while direct chlorination with chlorine gas and oxygen released 85 per cent of zinc and 100 per cent of lead in a chloride condensate containing little impurities.

Jan 1, 1980

A simulation model of the load and haul process where the loader cycle has been subdivided into its individual components is used to consider the benefits derived from improved drill and blast methods. Field data from a Hunter Valley mine is u

Jan 1, 1998

Over the 20 years to 1990 the Australian mining industry, presently worth some $A60 billion, generated a negative real rate of return (McDonald, 1992); not surprisingly under-performing the returns from bonds and industrial equities. Over this same period more than $A70 billion was invested in expanding the Australian mineral industry.

Jan 1, 1993

Distal rhyolitic tephras from the Taupo Volcanic Zone are widespread in the Auckland urban region. Some are primary air fall or flow deposits but most are reworked. Their presence indicates potential hazard for the Auckland urban region from future eruptions of central North Island volcanoes and associated secondary effects. Geotechnical problems occur as a result of weathering of the tephras yielding sensitive materials.

Jan 1, 1990

By Hu Y, Li D, Qu G

In this paper the structural mechanism of the gold - lixiviant complex is investigated. The results show that there are two common characteristics in the outer orbitals for all the gold lixiviants: a) a (Y -type of HOEO to form the L-*Au co-ordination bond, and b) a it type f LUEOs, with symmetry the same as that of 5d orbitals of Au, to form L

Jan 1, 1993

The Ok Tedi open pit mine will have final wall heights in excess of 750m. The behaviour of these excavated slopes will be influenced by the presence of numerous defects. This paper discusses the identification of possible failure mechanisms within the pit walls based on mapped fault and joint data. Results from analyses using these data have formed the basis for the ultimate pit design.

Jan 1, 1994

This paper traces briefly the reasoning which led to the decision to extend the existing internal shaft at the Rosebery Mine and to instal underground a larger winder (No. 2 Hoist) with capacity to handle all hoisting requirements to a depth of approximately 2,500 ft. on an incline varying from 83" to 55" to the horizontal. It then covers the specifications and selection of the winder, the design of the winch chamber, rope raise and bins, the excavation, support and lining of the chambers and the transport to site and installation of the machinery. Finally a brief description is given of the mechanical and electrical parts of the winder.INTRODUCTIONThe existing shaft winder on the internal inclined shaft situated on No. 8 Level of the Rosebery Mine had reached the limit of its capacity. Hoisting 21-ton capacity skips in balance, with a 13/16-in. diameter rope, it required four layers of rope on the 3 ft. 6 in.drums to reach the loading station under No. 12 level at a depth of 864 ft. (Fig. 1). This entailed heavy wear on the multi-layered rope and heavy stresses on the cheeks of the drums. Continuous working on three shifts was necessary to handle ore, men and materials, and a hold-up from any cause whatever meant an interruption to production on the lower levels of the mine. The maximum output of the hoist whilst hoisting from the No. 12 level loading station was 50 tons per hour. It was obvious therefore, that a larger winder was required if output was to be maintained.Diamond drilling had proved the existence of sufficient ore at depths well below No. 12 to warrant exploitation and a decision had to be reached on the means of hoisting this ore.

Jan 1, 1958

The face of project evaluation is changing continuously, making it ever more critical to get a clear understanding upfront of the objectives, decision-making processes and criteria of the project proponents. Requirements are usually significantly different for emerging æjuniorsÆ compared with long established major mining houses and companies in developing countries compared with western companies. Requirements are also different for different types of evaluations, such as due diligence studies compared with feasibility studies of æownedÆ projects and there are often key misunderstandings around the use of the term æbankableÆ. Further, it has become increasingly important with increasingly remote and lower quality resources to understand risk relativities such as infrastructure compared with the core processing facilities. This has also driven the need for more trade-off studies to determine the best balance between critical issues, such as optimisation of the interface between mine and processing plant, capital versus operating cost and automation versus labour. In every project evaluation, it is also critical to consider emerging trends and changing requirements and standards such as sustainability and community interface. Finally, the inescapable drive to reduce time to market has driven changes such as increased use of more standardised designs and innovative approaches to the transition from project development to execution. This paper begins with a brief review of the different objectives and risks of each project development stage to establish a framework for subsequent discussion of the different requirements of different types of companies in different locations, different types of evaluations and different types of projects and project components. This is followed by a review of changing requirements and standards and some innovative developments in sustainability and community interface are presented. Finally, the paper outlines a number of developments in the area of operational readiness planning that focus on minimising the time to achieve maximum return on investment.

Jan 1, 2009

By K Biegaj

The paper describes challenges the author has encountered on Australian underground gold and nickel mines over the last eight years, when recovering high-grade gold/nickel bearing mine floor material with a mobile supersucker/giant vacuum cleaner and other equipment. Whilst for a number of years the mine floor vacuuming and other mine floor clean-down technologies have been accepted/adopted and are working well in other parts of the world and on the South Australian opal mines, regrettably, they have not yet gained acceptance of mining executives and mine managers of gold and metal mines in Australia, who still elect to leave the never to be recovered gold/metal behind or to put it plainly - waste it.For reporting purposes during the mining process, the portion of gold/metal included in calculation of ore reserves prior to obtaining capital funds for their development, continues to be camouflaged in various reconciliation and call factors. This approach, ie wasting of capitally developed and already broken ore stocks should be viewed by the shareholders as totally inappropriate to say the least, especially with the current gold and other metals prices.The author attempts to provide answers as to why the technology referred to above has not yet been accepted on Australian gold and metal mines and outlines the way forward.CITATION:Biegaj, K, 2012. Why do shareholders and mining executives allow mine managers to leave behind high-grade broken ore underground?, in Proceedings Narrow Vein Mining 2012 , pp 197-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Ryan CG, Ramsden AR, Sie SH, French DH, Griffin WL

Proton microprobe and electron microprobe analysis are being used in combination for in situ determination of the trace element contents of oxide, sulphide and silicate minerals in a sample of the Merensky Reef. Initial results indicate that chromites contain only Ni, Zn, Ga, Zr ar d Nb. Platinum-group elements, if present, are at concentrations less than 2 to 6ppm. Ru, Rh and Pd are the only platinum group elements to be consistently detected in the sulphides. PentLindite is the most important host for these elements with the concentration of these elements being dependant upon the mineral association in which it occurs

Jan 1, 1989