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By A E Reschke

The high-shear colloidal mixer is generally recognised as the most efficient method of mixing cement based grouts. Only recently however has this technology been applied to the production of cemented rockfill (CRF) for use in underground mines in North America. Traditionally, paddle type mixers have been used to produce the cement based slurries required for the preparation of CRF. While considerable success has been achieved with these mixers, tremendous advantages are attained with the colloidal mixer. The combined effect of the highly efficient mixing action and the ability to mix low water/solids ratios, allows for reductions in the cement content for a given strength requirement. Cement can also be replaced by cheaper fillers such as flyash, resulting in further cost savings. Although large-scale dedicated CRF hatching plants are typical, there is a growing need for mobile plants capable of operating anywhere underground. The compact size and rapid hatching speed of high-shear colloidal mixers has allowed them to be incorporated into skid mounted systems capable of producing and discharging cement based slurries onto rockfill aggregate for the production of CRF. In many cases run-of-mine development waste can be used as CRF aggregate with these slurry plants thereby reducing the cost of waste rock removal. These relatively low cost portable plants have now allowed several mines to economically rccmer isolated pillars and realise positive returns on their investment.

Jan 1, 1998

By Dunn J, Nguyen G, Graham J

A pyritic gold concentrate from the Golden Mile, Kalgoorlie, was roasted over a range of temperatures in a pilot scale fluid bed reactor. The calcines were subsequently cyanide leached. Mineralogical studies of the con- centrate, calcines and leached residues were also undertaken. Calcines produced at 500'C gave the poorest gold extractions and high cyanide consumptions. Gold recoveries of approximately 90 per cent were obtained from calcines produced at 550-600'C but higher roasting tempera- tures resulted in an increase in the residual gold content of the leached calcine. There is some evidence of flash smelting of the pyrite at the higher roasting temperatures and encapsulation of gold particles. Mineralogical examination of the calcines shows that the mechanism of oxidation is temperature dependent. At 500'C pyrite is directly oxidized to hematite with a concentric layered texture which appears to inhibit lixiviant access to enclosed gold particles. At higher temperatures the conversion sequence pyrite-pyrrhotite-hematite produces a spongy calcine which al- lows easier penetration by the leaching medium.

Jan 1, 1991

The Barra Mine was the most significant mine of Australia's earliest mining era, which took place in South Australia between 1841 and 1851, the decade prior to discovery of gold in eastern Australia. Between 1845 and 1860, Barra was the largest metalliferous mine in Australia and employed up to 1000 men and boys, most of them Cornish.""Today the site is also important in a physical and archaeological sense as it contains extensive remains of mining and processing operations of the period 1850 - 70. Most significant are three cnginchouses which housed Cornish beam engines.

Jan 1, 1993

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

Mechanical and electrical (M&E) systems in road tunnels are constrained by the traffic envelope and the construction profile. Whilst these spatial constraints are often ælocked inÆ early in the design process, the detailed M&E design continues for some considerable time after key civil engineering issues have been resolved. Ventilation design criteria for both normal and emergency operation often involves considerable negotiation with a wide range of stakeholders. Final system performance and spatial requirements are only finally resolved when suppliers are selected following the tender process. Lighting design is dependent upon a wide range of factors including tunnel lining materials and associated colours as well as agreed maintenance regimes. Cabling systems can only be developed when the general arrangement for power distribution is agreed and a system of substation, switchrooms and equipment rooms is in place. Many other systems such as fire protection and communications facilities fill the available space beyond the traffic envelope, where physical, structural and æsight lineÆ requirements must all be accommodated. The more co-ordinated civil engineering and M&E design is and the earlier the process starts the better the outcomes for all parties.

Jan 1, 1999

By Iley J. D, Siviour N. g, Moffatt R. J

The process of desilverising by fractional crystallisation with reflux was investigated through laboratory batch tests and continuous laboratory bench scale tests at CSIRO Clayton, to a 300 kg/hr pilot plant at Port Pine. The pilot plant built at BHAS comprised a vertical cylindrical refining column with internal diameter 250 mm and height 3.2 m, attached at the top to an off-set cylindrical stirred crystalliser tank. Crystals were made in the crystalliser by intermittent immersion of steel cold fingers, which were water cooled between immersions. Gas heat was used for melting the crystals at the base of the column and for side compensation heating. A computerised in strumentation system was employed for data logging and for controlling some critical plant operations. A mechanical device was first employed to promote counter-current plug flow of crystals down the column against the rising stream of reflux liquid, but this was found to be unsatisfactory owing to excess noise, frequent mechanical failure, and excessive accumulation of dross. Plug flow was finally promoted by pulsing the column. Low silver levels, less than 1 gitonne, were achieved with both methods of crystal transport under total reflux conditions. The pulsed column gave results for silver and bismuth which agreed with the theoretical predictions of a computer model, but there was some selective drossing of antimony. In the mechanically agitated column, excessive drossing promoted selective removal of most of the antimony and some of the bismuth, and the results after extended operation were well removed from the theoretical predictions. Plant failures and operating problems prevented the achievement of satisfactory product quality with the necessary reliability under production conditions. Other priorities necessitated the termination of the project before the process could be optimised.

Jan 1, 1989

By Neill A, O&apos

The City of Kalgoorlie/Boulder is situated approximately 600 kilometres to the east of Perth (Fig. 1), and is the major regional centre of the Eastern Goldfields, supporting a population of approximately 25,000. The formation of Kalgoorlie Consolidated Gold Mines in 1989 brought the existing operat- ing entities adjacent to the city under common ownership and management. The Joint Venturers forming the management company are Homestake Gold of Australia and Gold Mines of Kalgoorlie (a Normandy/Poseidon com- pany). This traditional underground mining centre has been worked since 1893, yielding 40.8 million ounces of gold from ore with an average head grade of 10 grams per tonne. Historically the heart of the operation has been the famous Golden Mile located on the Eastern perimeter of the city, in the area known as Fimiston. The other significant operations that form KCGM are the Mt Percy Open Pit and the Mt Charlotte Underground Operation. KCGM's current production is 520,000 ounces per year, with the com- bined Fimiston operations (open cut and underground) contributing 400,000 ounces. The current expansion will increase production levels by a further 150,000 ounces. Traditionally 98 per cent of gold has been sourced from underground areas, however the recent upsurge of open cut operations is rapidly overturning this historical relationship.

Jan 1, 1991

By D Van Doorselaere

The purpose of blasting during mining is to produce a muck pile that can be efficiently loaded and transported. There is an increasing awareness of the variation in muck pile characteristics and its economic implications. It is well known that good fragmentation by itself is not sufficient to optimise the muck loading efficiency. The swelling and configuration of the muck pile also significantly affect the productivity of the loading equipment. The characteristics of a muck pile depend upon the blast design parameters, explosive properties and rock mass geology. This study has focused on the dependence of muck pile configuration on blast design parameters, explosive properties and size distribution of the muck.The field work was done in two phases. In the first phase 12 blasts were monitored, while in the second, three blasts were monitored. The blast design parameters and explosive properties for each blast were documented and the following muck pile characteristics were measured:muck pile height and its distance from the facedistance of throwwidth of the power troughsize distribution by image analysis technique.The effects of burden, bench height, heave energy of explosive, row-to-row delay, powder factor and the mean particle size of the fragments on muck pile configuration were examined. It was observed that muck pile height and distance of throw are strongly influenced by the burden, bench height, heave energy of the explosive and the size distribution of the muck. The width of the power trough depends upon the row-to-row delay, powder factor and total burden. In addition, the effect of the fragment size distribution on the muck pile parameters has also been discussed.CITATION:Singh, S P and Van Doorselaere, D, 2015. The relationship between blasting parameters and muck pile configuration, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 369–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Linge HG, Klauber C

The key element in the carbon-in-pulp process for gold processing is the loading of dissolved Au(CN)2 from solution onto activated carbon. The mechanism and kinetics of this step have been examined by solution adsorption-desorption and X-ray photoelectron spectroscopy for both coconut derived activated carbon and peat-based activated carbon. The results show that these carbon types have the same mechanism and kinetics of adsorption. There is no contribution to the bonding from carbon-oxygen functionalities on the carbon surface, as has been invariably supposed in all previous theories for the mechanism of the reaction. It is shown that Au(CN)Z is reversibly adsorbed intact on and parallel to the graphitic planes of the carbon with the formation of a weak carbon-gold n-donor bond. The kinetic measurement of carbon gold loading reactivity is discussed and use of the Murdoch equation for this test is critically assessed.

Jan 1, 1989

By B Morey, J Gordon, P Mackenzie

Mount Tom Price Mine is peerless amongst Rio Tinto iron ore resources around the world. It has provided Hamersley Iron with premium quality, high lump yield haematite ore over the last four decades. The Brockman type bedded ore, containing bands of haematite and shale of varying thicknesses has been traditionally bulk mined to either high-grade or low-grade based on alumina cut-off grades. As open pit mining has progressed deeper into the orebody approaching the keels of the megastructure, increased structural complexity, chemical and physical variations in the ore, unfavourable ore presentation and reduced blending options have become an issue for grade control and may have serious impacts on product stockpiles. The grade blocks and boundaries must be accurately defined according to geological contacts and where identified, selective mining may be applied. Therefore in-pit geological mapping is the definite and ultimate guide to achieve target grades and grade predictions. Under this scenario, it is absolutely vital that the mine geology team ensures this geological knowledge is passed onto the related departments including mining crews as well as to the short- and long-term planners.

Jan 1, 2002

By McClarnon D. J

This paper aims to provide the reader with an insight into the field of computer graphics and Virtual Reality (VR), and show how both have been applied to the general area of Free Steered Vehicle (FSV) operations underground. It first explains this developing computer technology and explains its advantages over existing CAD based solutions. This paper deals with the graphical applications and implications of building models within a computer's memory. It then continues to describe the problems with Free Steered Vehicle operations. The work already carried out in the field of VR is explained, and the production of a VR system addressing the problems with fitting cameras to aid the driver's field of view is detailed. Another possible use of VR is also explained - the concept of risk regions, demonstrating its uses in the examination of proposed operational methods. Examples of possible uses are given, and its potential advantages over existing methods discussed. A case study of a computer-generated video involved with the safety of operations of FSVs is also presented. This addresses the precautions that pedestrians should take to ensure safe working in areas where FSVs are operating. This paper then concludes with possible further applications for computer graphics and VR, and the on-going research into these two technologies.

Jan 1, 1995

By B BussiFre, J Molson, M Aubertin, G W. Wils

Waste rock piles containing reactive sulfide minerals can serve as long-term sources of acid mine drainage (AMD). Within these piles, many physical, geochemical and biological processes can contribute to the production of AMD. The flow of water, for example, depends on internal pile structure, which depends on the dumping methods used to construct the pile. In this paper, the internal structure and grain size distribution of typical waste rock piles are first reviewed with respect to their effect on internal water flow. A numerical model is then applied to simulate unsaturated flow within a waste pile assuming two primary waste materials, different atmospheric conditions and several geometric configurations. The simulations suggest that water movement can be controlled by introducing fine-grained material layers within the coarser host material. However, these layers should not be horizontal because they can lead to localised high-saturation regions as well as preferential flow favouring the production of AMD. A shallow slope towards the pile boundary may be introduced to force drainage to the outside while maintaining low saturation within the interior, thus reducing the production of AMD.

Jan 1, 2003

Underground mining of the ore below the West Lyell open cut commenced in 1972 with the 10 Series stopes above rail haulage level. The third lift of stoping (30 Series) com- menced this year, and access to the 40 Series stopes is being developed. The method uses transverse open stopes with subsequent mass blasting of the rib and crown pillars and consequently there is sub- sidence and caving of the old open cut area above.

Jan 1, 1982

By Mahoney M

For gas content analysis in recent years, it has been standard procedure to report results on a 'dry ash free' (daf) basis, under the assumption that gas only adsorbs onto coaly material. In order to test the relationship between ash and sas content, samples of various rock types were taken from two drillholes in the Newcastle Coalfield. The results of this study confirmed the correlation between gas content and ash, providing an accurate means of relating gas contents for all carbonaceous rock types.

Jan 1, 1995

During the course of an investigation into the fundamental chemistry of the cyanide process, it became evident that the usual method of determining protective alkalinity was not completely satisfactory. T.he routine method for the determination of protective alkali by first removing free cyanide by the addition of silver nitrate, followed by titration of alkali with dilute acid using. phenolphthalein as indicator, can be shown to give correct results only when the alkali is a strong base. For other sUbstances, the alkali so determined is not the protective alkali. In view of the complications associated with the presence of zinc in cyanide solutions the discussion will be restricted in the first place to solutions free from zinc. Until the chemistry of simple cyanide solutions is placed on a quantitative basis it will be difficult to elucidate the behaviour of complex mill solutions.By the use of physico-chemical theory, it is possible to treat certain aspects of 'the chemistry of cyanide solutions in a manner which not only illustrates the important variables involved, but which also shows the need for care in interpretIng results obtained by conventional methods.In the following, comparatively simple systems are discussed; the principles established should be of use in interpreting the behaviour of more complex solutions. The methods described are not intended for routine work, but may be regarded as supplementary to the usual analysis carried out for the control of plant solutions, or as alternatives to be used when the latter do not appear to be satisfactory.

Jan 1, 1948

By P Moser, P Schimek, F Ouchterlony

This paper summarises the findings of 27 model-scale bench blasts in magnetic mortar, which were conducted from 2011 to 2014 at the blasting site of the Montanuniversitaet Leoben.The aim of the study was the investigation of the influence of blasthole delay times in small-scale bench blasts on the face characteristics and cracking damage created in the surrounding rock, which affects the fragmentation in subsequent rows.The test specimens or blocks, which were produced out of magnetite concrete, were roughly 1:100 in scale to normal bench blasts. The confinement of the testing blocks at the sides and back ensured the similarity to normal bench blasts with regard to the wave transmission into the surrounding rock. The specimen contained three or four rows with five blastholes each and were shot row by row, with virgin (undamaged) material in row 1 and increasingly damaged or preconditioned material in the following rows.The tested delay times varied between 0, 28, 73 and 140 µs, which corresponds to 0, 0.4, 1.0 and 2.0 ms/m of burden.The evaluation of the material properties showed that the use of magnetite concrete eliminated the inhomogeneous behaviour of rock, but some unexpected differences of the individual production cycles were still detected.The characteristics of the bench after each blast was evaluated along three horizontal lines out of a 3D model of the bench face. The tested delay time sequences of the virgin (first row) and single preconditioned blasts (second row) produced more overbreak for longer delays, while the third-row shots resulted in a smoothened surface independent of the chosen delay.The introduced damage after every blast was evaluated by an observation of irregularities on the newly blasted bench face. The visible cracks at the top of the testing blocks were documented and divided into several crack families according to their angle, length and origin. The remaining block was broken out of the blasting site after blasting, cut into several horizontal and vertical slices and dye penetrant spray was used to visualise the cracks created. Some of the detected crack families showed an influence of the delay time. The calculated mean crack density and mean crack intersection density showed that longer delays resulted in a higher degree of damage.The fragmentation results were well reproduced by the basic three-parameter Swebrec function. The observed improvement of fragmentation in the second- and third-row blasts was linked to the preconditioning of the burden for the following row while blasting the actual row. With the exception of the simultaneously initiated blastholes, the blasts showed coarser fragmentation for the shortest delays, while the longest delays generated the finest fragmentation.CITATION:Schimek, P, Ouchterlony, F and Moser, P, 2015. Influence of blasthole delay times on fragmentation as well as characteristics of and blast damage behind a remaining bench face through model-scale blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 257–266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The Granites Gold Mine has far exceeded the design capacity of 300,000 tonne per annum during its first sixteen months of operation. The presence of considerable free coarse gold has made it imperative that the gravity section operate at maximum efficiency. The inadequacy of acid digest- ing facilities and trying climatic conditions prompted management to initi- ate investigations into the use of Intensive Cyanidation as an alternative method for upgrading gravity concentrates prior to smelting.

Jan 1, 1988

By S M. Denn

The Cawse nickel-cobalt operation is situated 50 km NW of Kalgoorlie in Western Australia, at latitude30o22'30'' south and longitude 121o08'30'' east on the Kalgoorlie 1:250 000 geological map sheet (SH 51-9) (see Figure 1). The project is owned and operated by Centaur Nickel Pty Ltd (CTR) and was the first in Australia to commercially produce nickel metal and cobalt sulphide through pressure acid leach (PAL) technology. Cawse has a total resource base (all categories of resources + reserves) of 213 million tonnes Mt at 0.7 per cent Ni and 0.04 per cent Co, comprising 127 Mt at Cawse Central which is 100 per cent owned by CTR and 86 Mt at Cawse Extended where CTR has a 80 per cent equity. Cawse Extended is located immediately to the northwest of the Cawse Central leases. All current reserves (proved and probable) of 30 Mt at 1.0 per cent nickel are contained within Cawse Central. In addition the Siberia project area 20 kilometres to the NW has a resource of 63 Mt at 0.7 per cent Ni. Cawse is a dry laterite deposit, with nickel and cobalt hosted by iron and manganese oxides. Cawse Central mineralisation extends over a ten kilometre strike length, with three pits currently being mined. The Bunyip pit has the premier nickel and cobalt grades within Cawse Central. There are seven dominant lithology types forming mappable units within current pit exposures. Four of these units are host to nickel and cobalt mineralisation. Ore types are defined as Upgrade, Grind and Non-upgrade, depending on their physical characteristics with respect to the treatment route. Mining commenced in February 1998. To the end of calender 1999 the operation has produced 2100 tonnes nickel plate and 470 tonnes of cobalt as a cobalt sulphide product. Future production will target 9000 tonnes per annum Ni metal and up to 2000 tonnes per annum Co, based on processing 500 000 tonnes of ore per annum.

Jan 1, 2000

By J H. Kyle

Cyanide is a significant cost in gold processing, as well as an environmentally sensitive issue. It has been suggested that precipitation of cyanide from leach liquors as copper-iron-cyanide compounds such as Cu2Fe(CN)6 may account for part of the total cyanide consumption. This may be especially true for ores that are rich in both copper and iron minerals. Ammonia addition has been shown to decrease the cyanide consumption by copper. Cu2Fe(CN)6.xNH3 precipitates have also been postulated to form during conventional cyanide detoxification processes, using oxidants such as SO2/air, with ammonia arising as a breakdown product from the oxidation of free cyanide. The present work has examined the conditions under which such precipitates may form, particularly in gold plant process and detoxification liquors. Ammonia and pH were found to have a large effect on the extent of precipitation. The compounds that were formed were found to comprise mainly Cu2Fe(CN)6.7H2O, as well as a range of NH3-bearing variants. The stabilities of the various precipitates are important from an environmental perspective. The long-term stability of copper ferrocyanide precipitates in tailings dams may be a problem under alkaline conditions and when some free cyanide is present, elevating the measured total cyanide in solution significantly. Case studies including data from actual plants are also considered, and the importance of these effects is reaffirmed from these results.

Jan 1, 2000

By O Ostrovski

Iron ore reduction and iron cementation by CH4-H2-Ar gas was investigated in a laboratory isothermal fixed bed reactor. Iron ore was first reduced to metallic iron by hydrogen, then carburised to cementite by methane. Increasing temperature and hydrogen content accelerated the reduction process. Methane had almost no effect on the reduction process. Meanwhile, higher temperatures increased the rate of cementation and also the rate of free carbon deposition. The optimal temperature for cementite formation was found to be 750¦C. At this temperature, reduction of iron ore to cementite by gas containing 55 vol per cent hydrogen, 35 vol per cent methane and 10 vol per cent argon was completed in about 15 minutes. Addition of sulphur into the reducing/carburising gas strongly retarded the process of cementite formation and free carbon deposition. Cementite is an unstable phase which decomposes to iron and carbon. The rate of cementite decomposition increased with temperature up to 600¦C and above 750¦C . In the temperature range from 600¦C to 750¦C the rate of cementite decomposition decreased with temperature. Cementite was the most stable at 750¦C and least stable at 600¦C. The two-interface grain model was used to describe the process of iron ore reduction and the volume reaction model was employed to model the iron cementation process. The simulated results for both reduction and cementation are consistent with the experimental data.

Jan 1, 2000