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By S Smith

Several styles of copper (Cu) mineralisation are present at Sepon. Large tonnage, low grade skarn and carbonate replacement massive sulfide mineralisation occur within the metamorphic aureole of Permian-aged rhyodacite porphyry intrusions (RDPs). During exhumation and supergene weathering, this primary mineralisation has been upgraded to form high-grade chalcocite enriched zones up to 50 m thick, which comprises the bulk of Cu resources currently being mined at Sepon. Groundwaters remobilise Cu to form exotic accumulations of malachite that are locally hosted in irregular karsts in carbonate rocks, found up to 1000 m from source mineralisation. Khanong is the largest Cu deposit and recent discoveries have been made at Thengkham South, Thengkham North and Phabing. All deposits have formed by similar processes of mineralisation. However, all differ due to local variations in host rock lithology, structural setting, and hydrological conditions. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Thompson D, Burgess G. C

Subsequent to large scale trials in 1987, the installation of a submerged lance Sirosmelt furnace system was approved in late-1988 for the cupellation of retort bullion to dore silver. Commissioning work commenced in June 1990. During the process air is lanced into a molten slag bath contained in a cylindrical vessel to rapidly oxidise the granulated feed bullion from 15 - 25 per cent silver to rough dore grade. The process is now an integral part of the Precious Metals operation replacing the first stage reverberatory cupellation furnaces to achieve productivity improvements, lower silver inventory and increased silver Recovery.

Jan 1, 1992

By Strickland R. E J

Heap leaching is establishing itself as an efficient method for the extraction of gold from low grade ore. It has the advantage of low capital costs, low operating costs and rapid startup. However, not all ores are amenable to heap leaching. It is only applicable to well oxidized ores that have reasonable permeability characteristics. Ore with excess fines or clay often display low permeability and are unsuitable for heap leaching.In this study, an attempt has been made to increase the rate of cyanide leach solution percolation by flocculating clay particles or reducing the surface tension of the leach solution. A wetting agent was found to decrease the rate of gold dissolution, possibly by presenting a hydrophobic surface to the gold particle. Flocculation of the clay increased the solution flow rate. The flocculation agent had no affect on the total gold leached but decreased the leaching rate.

Jan 1, 1992

The environmental and social responsibilities of the mining industry have long been recognized by the industry itself, but during the past decade it became one of the main targets for the more radical members of the community. This came as something of a shock to an industry which had always considered that it had acted responsibly within the standards of the day. As far back as early 1968, the Australian Min- ing Industry Council (AMIC) was clipping from newspapers the odd letter written by environmen- talists and critics of mining activities. In those days every such letter was carefully studied to ensure that AMIC, if not having the answers, at least had an understanding of the types of argu- ments then starting to be used against mining activity and in favour of environmental preserva- tion. Within 18 months, the infrequent letter to the editor had become a flood of such letters and feature articles, and the environmentalists' attack on mining activities had been launched in all its Vehemence.

Jan 1, 1978

By Leahy GJ, Wright DJ, Player RI

The operation of a one tonne submerged combustion pilot plant for the recovery of copper from anode furnace and converter slags is described and the effects of variables discussed. Using coal as reductant, copper levels of anode furnace slag were lowered to 1% or less, with batch times of approximately 120 minutes. Fluxing with limestone was required to produce a fluid slag at temperatures of 1200 - 1300¦C. For converter slags, reduction to 0.5% Cu or less was achieved in batch times of 35 minutes. The chemistry of the pyrometallurg- ical recovery of copper is briefly reviewed in relation.to copper recovery methods.

Jan 1, 1978

At the LKAB, Iron Ore Mine, Kiruna, Sweden a preliminary investigation into the reliability characteristics of a fleet of load-haul-dump machines has shown that the hydraulic system is one of the most critical parts. Therefore, hydraulic system was selected for study and analysis through condition monitoring devices so that failure can be controlled or at least the failure consequences can be minimized.The hydraulic system has two different problems; one is that the contamination level is too high and the other is high temperature during operation. At high temperature, seals and tubes are a problem, because they stiffen due to carbonization, which leads to increasing leakage. The pumps and restrictions were responsible for the main temperature increase.

Jan 1, 1991

Australian continental crust has accreted and consolidated by thirds: 1/3 during Archean time, 1/3 during Early to mid-Proterozoic time, and 1/3 during latest Precambrian to mostly Paleozoic time. The progression of orogenic systems and the crustal consolidations they represent seem not fundamentally different in basic orogenic processes from better known Mesozoic-Cenozoic examples in that accretionary, continental margin, collisional, and intraplate intracratonic inverted and/or reactivated systems are all recognizable in the tectonic evolution ofAustralia.

Jan 1, 1995

By Showers JAF

The Western Mining Corporation mining lease on the Bendigo Goldfield measures 5krri x 18km with more than 20 anticlinal folds parallelling th long north-south boundaries. Numerous closely spaced shafts and extensive underground workings on the reef lines along the folds flooded with groundwater following the progressive abandonment of the field. Preliminary water sampling and assessment demonstrated that a major dewatering programme and acceptable disposal methods were necessary to dewater interconnected old workings in areas of interest prior to any underground work taking place. A field wide geohydolic investigation was undertaken to establish geohydraulic parameters, groundwater recharge rates and water qualities. Data from the field investigation together with estimates of the volume geometry of the submerged workings as obtained from old mine plans, production history, and limited pump testing results were used with an appropriate analytical model to obtain estimates of water discharge rates required to reach various dewatering targets. Water disposal options were limited by relatively high salinities, arsenic levels, contained hydrogen sulphide, and the mine locations within the urban areas surrounding Bendigo. Direct disposal to the surface drainage system could not be considered, treatment to acceptable discharge standards was not economically feasible, and it was necessary to adopt a strategy of collection, containment, and evaporation.

Jan 1, 1988

By A Hewitt

Portland cement is the chief binding ingredient in mine backfill. In the presence of water, the chemical compounds within portland cement hydrate causing hardening and strength gain. During hydration, heat is generated. In certain cases, hydration heat may be produced significantly faster than it can be dissipated, which can create high temperatures in the underground environment. This paper presents the results of a series of investigations aimed at quantifying the heat generated by cemented backfill during hydration. Scaled stope models, instrumented with thermistors, were used in the investigation. Heat transfer to the hanging wall, orebody, footwall and cross-cut and production drifts was assessed during the backfill curing process and relationships between cement content, cure time, and heat generation were developed. The results of this work will assist mine operators in predicting the heat generated by cemented backfill and provide the necessary information to implement effective engineering control of heat in the underground environment.

Jan 1, 2005

By Yesil MM, Bozdag T

This paper describes the conver- gence and load measurements carried out in inclined seams at five longwall faces, two of which were supported by hydraulic props and the other three by conventional timber supports in Karadon-Gelik mine. The minimum support capacities determined in this study are compared with the results obtained from two empirical approaches suggested by Wilson (1975) and Jacobi (1981). The characteristics of hydraulic props to be used and support patterns in the longwalls are found, conclu- sions are drawn and suggestions are made. Design nomograms are prepared for field engineers, in order to be able to approach the problem more confidently and realistically.

Jan 1, 1992

By Seymour D

The disagregation and privatisation of the mining and power gene ration operations of the former State Electricity Commission of Victoria has being taking place over the past five years. This has transformed the service provision to the new organisations and has resulted in major change to the working lives and professional relationships of thousands of Australians. The authors wish to take this opportunity to explore the issues arising as the program of privatisation of public assets continues. Changes within the workplace which resulted from the outsourcing of the 'investigation and design' functions and more lately as a result of privatisation of the operating, generating and distribution businesses are discussed. The responsibility of managers retaining the services of design engineers has changed. There is an added responsibility of contract administration and an increased focus on intellectual property and strategic issues. The way in which the sectors are adapting is discussed and future directions are explored. We welcome this opportunity to explore the changes in professional life which have taken place over the last five years in the Latrobe Valley Power industry. Engineers and earth scientists have a pivotal role in the continuing successful operation of the three Latrobe Valley Mines of the generation companies. The Mines' collectively excavate annually over 13 million cubic metres of overburden and 48 million tonnes of coal for delivery to mine-mouth power stations and for briquette manufacture.

Jan 1, 1997

By R van Berkel

Regional synergies concern the capture, recovery and reuse of by-products, water and energy between industrial operations in close proximity. The Centre for Sustainable Resource Processing (CSRP) undertakes applied research to further advance regional synergies in the Kwinana Industrial Area in Western Australia in order to achieve greater efficiencies in water, energy and materials consumption and reduction in waste and emission generation. The Kwinana Industries Council (KIC) and its member organisations recognise water consumption and disposal as key environmental issues. Some 30 companies in Kwinana consume a total of more than 35 000 ML/yr of fresh water. Over the past years significant progress has been made towards the reduction of water consumption and improvements in effluent disposal. As part of the CSRP Kwinana Synergies Project, water balances for the ten major water consuming companies have been completed, including workshop sessions with company staff on water synergy opportunities. This work resulted in a set of synergy opportunities which are currently being pursued. In parallel to the Kwinana project, the CSRP has commissioned a supporting project that delivers a toolkit to guide a more targeted and less resource intensive way to identify feasible water synergy opportunities. One of these tools focuses specifically on water, and takes count of input and output water flows within a given industrial area to deliver listings of prioritised water synergy opportunities. This paper discusses the water mapping and workshop approach taken in Kwinana and its outcomes, which are to identify and evaluate water synergy opportunities. The results from the trial application of the developed Regional Eco-Efficiency Opportunity Assessment Toolkit are also presented.

Jan 1, 2006

Hamersley Iron Pty. Limited has maintained an interest in the screening of iron ore fines (nominally -6 mm). However, no dry screening process had successfully demonstrated acceptable separating efficiencies at high tonnage rates, low operating costs, and mechanical reliability when screening iron ore fines (containing up to 6% free moisture) at sizes of around 1 to 2 mm. A new type of vibrating inclined screen has recently been developed which is claimed to have a non-blinding screening surface. It was decided to test a pilot scale unit in an existing pilot plant located at Hamersley's facilities at Dampier, Western Australia. The appropriate operating parameters such as vibration speed and feed rate were determined using one fine ore type. Mats with different aperture sizes, and different feed moisture contents were also tested. Trials were then conducted on various fine ore types to indicate the effect of different size distributions on separating efficiencies. The effects of feed moisture content were determined with these ore types, and a blend of lump (nominally -30+6 mm) and fines was tested to compare the screen's performance with that of the bottom deck of the minesite product Screens.

Jan 1, 1991

By A M. Robertson, R Lefebvre

Air movement and associated oxygen transport through waste rock dumps has the potential to significantly enhance the rate of oxidation of pyrite-bearing material. While this is a desired outcome for most heap leach operations, airflow in waste rock storage facilities can result in significant increases in generation and acceleration of acid rock drainage. Hence, a good understanding of internal airflow through waste rock dumps is required to control ARD and minimise any associated liability. The principal mechanisms contributing to airflow and oxygen transport in a waste rock pile include: diffusion; advection due to a thermal gradient (chimney effect) and/or wind pressure gradients; and advection due to barometric pumping. While diffusion is typically limited to a near-surface zone of a few meters depth, advection and barometric pumping have the potential to move air (and oxygen) to much greater depths into the pile. In general, the more permeable the waste rock material, and the greater the height-to-width ratio of the waste rock pile, the greater is the potential for advective air movement. The reactivity of the waste rock material as well as the coarseness (hence air permeability), and the spatial variability of these properties within a pile, have a strong influence on the magnitude of thermally induced advection. In contrast, air movement due to barometric pumping is controlled by the waste rock porosity, changes in ambient air pressure and the heterogeneity of air permeability of the waste rock dump. Results of field monitoring and numerical modelling using TOUGH AMD are presented to illustrate the concepts on air movement in waste rock piles discussed in this paper. During the design and construction phase, airflow can be controlled by judicious placement of reactive waste rock and use of selective placement techniques to control the internal structure of the waste rock facility (eg introduction of horizontal layering, prevention of inclined, high-permeability, channels (æchimneysÆ)). Several closure measures are available to minimise airflow including: placement of a low-permeability cover to reduce air entry; and placement of a non-reactive cover material to isolate reactive material from the zone of active airflow and/or regrading of the waste rock pile to obtain a geometry and internal structure less susceptible to advective airflow.

Jan 1, 2003

Multi Torque Industries and Jadefoil have developed a safer, more efficient method of explosive protection, retention, placement, and constraint. In particular, this refers to advancements in airbag technology, where the system will offer an alternative to conventional gasbags and decking methods to provide a far more controlled and safer working environment. Airbags have provided operator control and reliability which has not until now been possible in this type of application. The benefits have been noted by current users and the advantages have provided an increase in productivity and significant savings in explosive waste. Obvious problems with gasbags lie in their instability in hot conditions where the danger is associated with gas canisters exploding with great force posing a significant risk to operators. Other problems associated with the decking systems currently on offer is the lack of versatility and operator control. The airbag systems give the operator full control to guarantee accurate placement, assured retention whilst boasting a quick operation of less than a few seconds for conventional void blocking, decking and plugging. One of the main advantages of the airbags is that the operator has full control over placement and retention force, therefore in wetter conditions where slippage can be a problem extra air can be added at the operatorÆs discretion to ensure a sufficient grip. Technical calculations coupled with experimental testing have demonstrated that an airbag will support the weight of a 30 m water column in an 89 mm hole at an initial bag pressure of 5 psig. Applications are increasingly growing whilst more customers embrace their use. Advancements such as the ability to deck in overhead holes, block voids in overhead holes at any depth, explosive retention in very wet conditions, longhole stabilisers to prevent hole closure and concertinaed liners reflect a dynamic potential for new technologies. All of these applications provide a decrease in explosive waste, an increase in operator safety, an increase in explosive protection, and an increase in productivity.

Jan 1, 2004

By Moyes A. J

The Intec Copper Process uses a strong chloride electrolyte at atmospheric pressure and 80 - 85¦C to produce high purity, 99.99 per cent copper granules and elemental sulphur. A recent, exhaustive study by an independent, major Australian corporation has shown the capital cost of an Inter plant to be approximately half that of a copper smelter at the 200 000 tpa capacity level and approximately half the operating and capital cost at the 50 000 tpa level. The Inter process costs were also shown to be greatly superior to the best available leach/SX/electrowin technology. The process utilises a multi-stage counter current leach at 80 - 85¦C with the addition of air at atmospheric pressure to precipitate iron as a goethite type compound, followed by a two-stage purification process separating impurities in metallic- and other forms. Purified cuprous chloride/sodium chloride solution is fed to an electrolytic diaphragm cell where high purity copper granules are produced at current densities of 1000 - 1500 A/m2 withoutthe need for conventional electrode stripping. Power consumption is approximately half that of the cupric route. The product is suitable for the direct powder metallurgical conversion of the granules to products such as wire or strip. All the steps in the 'furnace free' conversion of copper mineral to product have been demonstrated The process can treat low grade and contaminated concentrates without penalty, thereby offering greater returns to the miner. Lead, zinc and silver may be recovered as metals, with the high oxidation potential of the electrolyte allowing extraction of gold at high efficiency. The gold is selectively precipitated on activated carbon with negligible copper and silver contamination.

Jan 1, 1992

By B Hall

In feasibility studies the choice of optimum cut-off grade is typically based on an evaluation of tonnage grade curves and manual design of stopes at one or two cut-off grades. In the industry these stope designs are usually based on break-even cut-off grades, but there is little consensus on what cost and price assumptions ought to be included. A new tool for automated stope design has been developed that generates sets of stope shapes for a nominated range of cut-off grades, or depending on the nature of the mineralisation, cut-off values based on net smelter return calculations in the block model. The stope design procedure includes constraints in stope and pillar geometry for the selected mining method and can be used to evaluate sublevel interval and sensitivities to other design parameters in the specific geological and geotechnical environment. These ænested stopesÆ are analogous to ænested pitsÆ in open cut design, and can be used as a key input in the æhill of valueÆ methodology for the evaluation of the optimum cut-off grade in underground design. The results of many consulting studies indicate that a break-even cut-off grade will not be the optimum cut-off grade. A particular benefit of the new stope design tool is that the design rules used to establish stope shapes in the feasibility study can then be used in mine production, in an optimal and repeatable method. This methodology is being advanced in the AMIRA P884 PRIMO project, which is a new research collaboration coordinated by AMIRA International. The project has brought together active research groups in Australia and Canada, with the goal of developing a flexible framework and set of software tools for optimisation in underground mine design.

Jan 1, 2009

The extraction of the values from gold bearing clay or clayey ores has always presented difficulties. A description of the successful operation of a mill working on material of this nature is here given in the hope that it will be of interest to mining engineers and metallurgists, particularly as the ore body referred to has been worked out. The methods finally adopted were evolved at the mill after the failure of 3: plant specially designed in England and sent out to New Guinea to cope with the clay by the old principle of calcining to brick followed by crushing and cyanidation. A description is given of the direct cyanidation of run of mine ore in '90 ton vats; which was finally adopted after a great deal of study and experiment. Mention is also made of the method of removing overburden in the open cut and the mining and transport of the ore from the open cut to the mill. The purpose of the paper is to record these matters while the information is still available. . .DESCRIPTION OF THE ORE BODYThe values occurred in a flat-lying lode which had slipped about half a mile down the mountain side and had come to rest in the nearly horizontal position in which it was found and worked. The thickness of the deposit varied from a maximum of about 25 ft. at the northern end to about 10 ft. at the southern end. The ore body was capped with an overburden of decomposed breccia and porphyry of variable thickness the maximum being about 65 ft. The underlying rock, or the footwaIJ of .the flat ore body was breccia locallyknown as blue breccia.

Jan 1, 1951

By Bogar D. V

Often dewatering of coal tailings is inhibited by the presence of clays, making it difficult to obtain a high concentration, handleable coal tailings. The net result can be a low concentration, chocolate mousse-like tailings which poses significant sedimentation problems in a tailings dam and represents a significant environmental problem. This paper examines the coal tailings from a Hunter Valley colliery where the tailings properties are influenced significantly by the presence of montmorillonite clay. The influence of the calcium ion on the rheology and sedimentation/compression behaviour of coal tailings . containing montmorillonite already dispersed in water was investigated and revealed that very little improvement in the properties is achieved through the coagulation. The preliminary investigations also indicated that the properties of the tailings were dominated by the presence of the montmorillonite clay. Thus investigations were carried out on the clay alone in water. Investigations into the effect of dispersing samples of the clay alone in water and then coagulating with calcium compared with dispersing the clay directly into calcium ion solutions at the same calcium concentration showed huge improvements in the rheology, compressibility, sedimentation rates and sediment solids concentrations for the second dispersion method, which can be called controlled dispersion. The sediment volume fraction solids improved by more than a factor of two by controlling the dispersion of the clay. The reason for the improved properties lies in the suppression of the initial swelling of the clay, which is initially in the sodium form, thus maintaining the parallel orientation of the platelets that is present before wetting. While swelling is being suppressed, ion exchange occurs with the calcium which results in permanent swelling suppression. In the uncontrolled dispersion case where swelling is uninhibited, the clay is allowed to break up and despite the powerful coagulating nature of the calcium ion, the random orientation of the high aspect ratio clay platelets inhibits effective coagulation. Results indicate that the initial electrolyte concentration of the washwater in a coal washery is the critical factor controlling the dewaterability of clay tailings and the handleability of the dewatered product rather than the actual act of coagulating with the calcium ion. The results presented are of clear practical significance and indicate how coal tailings problems where clay dominates the rheology can be improved considerably by knowledge of the surface chemistry.

Jan 1, 1995

By R Castedo, P Segarra, L M. López, J A. Sanchidrián, A P. Santos

The cylinder test allows us to determine the expansion of a copper cylinder by the detonation of an explosive charge inside. This test, originally designed for military explosives, has been adapted for industrial explosives with non-ideal behaviour. From data obtained with this test and known physical relationships, an analytical procedure has been developed to calculate the Jones-Wilkins-Lee (JWL) equation of state parameters for five ammonium nitrate/fuel oil (ANFO) and six emulsion-type explosives. A new radial wall expansion function is proposed considering a non-zero initial velocity with the consequent positive Gurney energy at unit relative volume. A set of equations is established to determine the JWL parameters, three of them obtained at the Chapman-Jouguet (CJ) point and the other three at different relative volumes. These equations, along with some constraints to ensure a physically sound solution, are solved for the JWL parameters by a non-linear least squares scheme. A 2D Lagrangian axisymmetric finite elements (FE) numerical model is developed for each tested explosive to validate the analytical results, in terms of expansion histories, with good agreement. This confirms that the set of conditions, constraints on the parameters and least squares calculation used constitute a robust methodology that fully captures the physics of the detonation products expansion involved in the cylinder test.CITATION:Castedo, R, Sanchidrián, J A, López, L M, Segarra, P and Santos, A P, 2015. Jones-Wilkins-Lee parameters for civil explosives, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 57–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015