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By S C. Dominy

For any gold deposit-based geometallurgical study, the collection and processing of representative samples for gold grade and recovery tests is critical. Sampling protocols should be designed to suit the style of orebody in question. The proportion and size of gold particles has a direct impact on the effectiveness of sampling protocols and metallurgical recovery processes employed. Studies focussing on ore mineralogy and gold particle deportment, size and distribution are required. Key issues are the presence of gold particle clustering (important for sampling optimisation) and proportion of coarse versus fine to refractory gold. X-ray computed tomography (CT) is a radiographic technique that produces high-resolution 3D computerised models of objects based on density distribution. The ‘virtual’ specimens are made up of voxels, the 3D equivalent of pixels each assigned a grey value based on X-ray absorption. This paper presents the results of recent research on the imaging of in situ gold particles in a coarse gold-bearing ore. The technique shows promise as a rapid non-destructive method for preliminary characterisation to facilitate more detailed studies. Early and rapid gold particle determination enables sampling protocol optimisation and metallurgical recovery parameters to be defined prior to detailed feasibility studies

Sep 5, 2011

By Abell RS, Wyborn D, Solomon M, Stuart-Smith PG, Henderson GAM

The two major massive sulphide deposits in the Silurian rocks of southern NSW, Captains Flat and Woodlawn, differ from classical Kuroko deposits in several ways, e.g. they lie on the flanks of felsic volcanic piles in volcano-sedimentary marine sequences, are relatively thin and large compared to individual Kuroko deposits, show prominent banding in lead-zinc ore, and contain arsenopyrite. Qualified stuctural and stratigraphic correlations of the various fault-bounded remnant Silurian sequences that host these deposits provide the basis for a new interpretation of the regional geological setting that also differs from that of the Kuroko deposits (Ohmoto, Tanimura, Date, Takahashi, 1983), and sheds further light on the distribution of volcanogenic massive sulphide deposits in the Silurian rocks of NSW.

Jan 1, 1987

By C E. Loayza, R M. Pinto, J G. G=mez

The Yanacocha District is located 20 km north of the city of Cajamarca, in the Northern Andean Orogenic belt of northern Peru.Gold production may have occurred as early as Incan times (Paverd, 2000), but modern exploration that began in the 1960s targeted only copper and silver. Newmont Mining Corporation, BRGM and Compa±fa de Minas Buenaventura began exploring for gold in 1983, with Newmont as operator.Initial drilling took place in 1985. By 1992 a reserve of 1.28 million ounces was reported (Teal et al, 2002).Production began at the Carachugo deposit in 1993.Current reserves are 31.7 million ounces at $US 325 per ounce at a grade of 1.03 ppm (Newmont Annual Report, 2003).The operating company, Mineral Yanacocha SRL (Newmont 51 per cent, Buenaventura 44 per cent and International Finance Corporation five per cent) produced 2.85 million ounces in 2003, making Yanacocha one of the largest gold mining operations in the world. The district is made up of a series of epithermal, high sulfidation style gold deposits and one gold-rich gravel deposit (La Quinua), aligned in a NE trend.La Quinua is not discussed in detail in this paper. The bedrock deposits are hosted in a Miocene volcanic package, the Yanacocha Volcanic Complex that also trends NE.Re gional NW striking Andean faults intersect the NE striking Trans-Andean Chicama-Yanacocha structural corridor (Turner, 1997), localising the district mineralisation. These two structural orientations dominate the district, controlling breccia and intrusion locations, and gold mineralisation. Discontinuous EW oriented fracture zones are interpreted as extensional and locally are important in controlling gold mineralisation.

Jan 1, 2004

The C.S.A. copper lead zinc mine, located seven miles north of Cobar in Central Western New South Wales, is the largest known mineral occurrence in the Cobar Mining Field. Hosted by the steeply west dipping, west facing sediments of the Cobar Group, the generally discordant orebodies occur within a strike width of 600 ft and an overall strike length of 1200 ft. They comprise lenticular steeply north pitching and east dipping zones of sulphide mineralisation which range in composition from massive pyrite-sphalerite-pyrrhotite--galena to less massive pyrite- pyrrhotite-chalcopyrite varieties. The thinly bedded siltstones, shales and graywackes hosting the mineralisation appear to have derived many of their constituents from volcanic sourcesä They have been metamorphosed to the greenschist facies of regional metamorphism. At least two stages of deformation and folding have occurred. The first stage folded the rocks on a south pitching fold axis into their present configuration, and super- imposed a strong axial plane cleavage which subsequently guided the emplacement of the mineralisation. The second stage of deformation is considered to have controlled the zonal distrib- ution of the orebodies and the appropriate fold axis appears to coincide with the long axis of the orebodies.

Jan 1, 1969

By B Olsson, B Reynolds, R Norman

An unprecedented growth in demand for coal exports has placed pressure on multi-user coal chains to guarantee that their capacity expansion projects will meet the required demand. These projects, however, are taking place in an increasingly complex commercial and technical environment - competing rail and coal terminal service providers as well as a myriad of competing mine operators, all needing to operate in an increasingly integrated manner to get the most out of expensive shared assets.Increasing system complexity and integration has driven the need for more holistic and sophisticated analysis tools. The capacity of coal chain subsystems, such as mine, rail and port, can no longer be determined effectively in isolation. Understanding the nature of the interactions between these subsystems, their sensitivity to uncertainty and the resultant capacity of the integrated system is the key to both maximising value and minimising risk.Recently, TSG has worked closely together with the Integrated Logistics Company and a number of key stakeholders in the Dalrymple Bay Coal Chain to develop independent system master plans. These master plans have provided a quantitative and rational assessment of coal chain capacity in its current state and a prediction of its capacity once a pipeline of committed capacity improvements is in place. This paper provides an overview of the study and a comprehensive guide to the process required to effectively achieve valuable strategic insights in a challenging multi-user stakeholder environment.CITATION:Reynolds, B, Olsson, B and Norman, R, 2012. Using independent system simulation to mitigate risk in the Dalrymple Bay Coal Chain, in Proceedings Project Evaluation 2012 , pp 77-84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By J Nemcik, E Baafi, I Porter, G Spinks

Spray-on liners used in the mining industry for ground support and stabilisation applications are either cement based (æshotcreteÆ) or polymer based (æthin spray-on linersÆ). Some thin spray-on liners are a blend of both polymer and cement (eg Tekflex). A small number of thin spray-on liners (TSLs) have been trialled in Australia as potential replacements for steel mesh in roadways and other underground mining applications; however, they were found to cure slowly and the cured coatings became brittle after an extended time in place. The University of Wollongong in collaboration with the Australian coal mining industry has shown that a viable polymer-based alternative to steel mesh in underground roadway support applications can be developed to eliminate the use and handling of steel mesh. The work to date has: established the feasibility of developing polymeric alternatives to steel mesh in underground roadway support applications; identified the physical and material constraints to be endured by any new polymeric skin reinforcement system by measuring the mechanical properties of steel mesh; identified materials that can be spray applied; and demonstrated that polymer mechanical properties can be optimised to produce similar mechanical properties (elastic modulus, yield stress, elongation-at-break, etc) to steel mesh. The identified materials will: allow the face support cycle to be fully automated, or at least remotely operated and installed; remove personnel from the immediate face area; and substantially improve underground roadway development rates.

Jan 1, 2008

During the 1950's there was a flurry of activity on the design of main ventilation shafts for mines. More recently, a new ana- lysis was commissioned in relation to the multi-shaft, nuclear waste isolation facili- ties currently under design in the United States. This paper presents the major find- ings of that study and should prove of value as a reference in the design of proposed new shafts. An overview of mine shaft resistance introduces the effects of the shaft walls, fittings, conveyances and shaft stations. Each of these is analyzed in turn. A com- pletely new technique is described, which facilitates the estimation of wall resis- tance. The effect of size of a conveyance is quantified and shown to be dominant when the cage occupies more than 30 per cent of the shaft cross-section. The dynamic effects of a moving conveyance are also analyzed.

Jan 1, 1988

By M Saghaeian, M Zare, V Sheikhzadeh, R Hejazi

High-Pressure Grinding Roll (HPGR) is one of the efficient methods for increasing the specific surface area (SSA) of iron ore concentrate for pellet feed production. HPGR grinding mechanism implies that material should compressed between the two rolls, therefore layer of material must be able to resist required pressure for achieving suitable grinding conditions. In this study, by doing SSA increasing tests with pilot HPGR, the effects of silica reduction on SSA increasing results were investigated. For this purpose, HPGR tests were performed on an Iranian magnetite concentrate before and after reverse flotation silica reduction tests. Based on the laboratory test results, silicates have been concentrated in two fraction sizes of the sample comprises coarser than 150 microns in form of quartz and finer than 7 microns in form of iron silicates. These silicates have been effected on reduction of concentrate bed pressure resistance by creating a pasty and sticky mud. In this condition, HPGR cannot work properly and operation results are not acceptable. According to flotation silica reduction tests, with 90 per cent weight recovery, concentrate Fe grade is increased from 67.8 per cent to 69.5 per cent and SiO2 content is reduced from 1.98 per cent to 0.9 per cent and especially for lower than 7 microns fraction size, as a critical fraction, SiO2 content decreased from 4.45 per cent to 2.35 per cent. HPGR tests were performed on 8 per cent moisture in 4 N/mm2 specific force and according to the results after silica reduction HPGR operation conditions are optimised. Results showed that the working gap increased from 7 to 10.5 mm and specific throughput of material raised from 180 ts/hm3 to 250 ts/hm3 , and SSA increased by 300 cm2 /gr in a single pass.

Aug 24, 2022

By Hayward SB

The Maragorik prospect is an example of high sulphidation, Cu/Au mineralisation occurring at a high level in the hydrothermal system. As extensive ash deposits blanket the region, controlled-source audio magneto-tellurics (CSAMT), in conjunct-ion with bulldozer trenching, have been used to delineate subsurface geology. Fluid upflow has occurred along EW structures dilated by rotation on the bounding major NW lineaments. Rising hydrothermal fluids have exploited permeable horizons in contact with the upflow structures. This lithological control is evident as ledges of silicification and peripheral clay alteration, at high levels in the system. As is typical of high sulphidation systems, a two phase fluid consists of an initial rapidly moving vapour-dominated phase, followed by a liquid-dominated phase. Much of the zoned and overprinted silica to clay alteration is developed from the vapour-dominated fluid. Mineral deposition occurs as a result of brecciation of the competent silic-ification by liquid phase fluids. Such mineralisation is of restricted volume in ledges proximal to the feeder structures.The style of alteration and mineralisation are indicative of a very low temperature and hence a high level system. Thus, although high sulphid-ation systems are inferred to develop from porphyry-related magmatic fluids, such a source at Maragorik is interpreted to be very deeply buried.

Jan 1, 1994

By Reeves I. And Farquhar J, Pearce S

The irregular shape of the Rosebery orebody, coupled with the inconsistencies in grade over short strike lengths, has meant stoping blocks have had to be small to combat dilution and stability problems. In the past, each lens was divided into regular block sizes and developed up to five years before production commenced. There were two major drawbacks to this practice; firstly, existing development deteriorated over time therefore requiring rehabilitation prior to production. Secondly, the pre-determined blocks could not be easily changed to incorporate changes in mining technology or economic circumstances. Bearing these problems in mind, it was evident that any new lens development had to be designed to allow maximum flexibility. The lens being currently developed is J lens. It represents approximately 50 per cent of the current reserves tonnes, and 65 per cent of the zinc metal. Its importance to the mine's future cannot be over emphasised. At its core the lens is up to 25 m thick at grades of over 30 per cent zinc. The practice of dividing the orebody into levels and sublevels, with consequent crowns was no longer acceptable because of restrictions in stope design and potential loss of ore. To assist in the development planning of J lens, a geostatistical block model was applied in long section to graphically represent the lens. Areas of high zinc concentration, as well as zones of uneconomic material were identified by using the model. This has meant that the development could he targeted, enabling stope delineation to occur in the lens without significant ore loss. Because of limited development resources, and the need to bring J lens on-line in the near future, the development strategy has had to focus on 'just-in-time' principles, rather than accessing the whole lens from bottom, and progressing upwards. Tight development schedules have required individual stoping block to be developed on such factors as grade and available tonnes rather than as a vertical sequence.

Jan 1, 1993

By Barnett DW

Financial risk analysis provides the tools to examine the uncertainty of capital decisions in new mining ventures. This paper explores the methodology by which financial risks can be studied and quantified. The most commonly used risk evaluation methods, such as sensitivity analysis and discount rate adjustment, are presented as an introduction to a more comprehensive discussion of stochastic methods of discounted cash flow analysis using Monte Carlo sampling. The discussion is illustrated with examples of a stochastic discounted cash flow. The advantages of Monte Carlo sampling in risk analysis are discussed together with its problems, particularly those originating from the correlation amongst the variables that determine the economic output of a mining venture, and the difficulties created by insufficient data, imperfect knowledge and complexity. The paper also surveys the most commonly used software used in risk analysis.

Jan 1, 1994

By N Esmaeili, M Saghaeian, L Hosseini, V Sheikhzadeh, R Hejazi

Ore roasting has long been used for beneficiation and assay upgrading of different ores. In this process, which is mainly used for sulfide ores, the ore is heated to a high temperature. More specifically, it is a metallurgical process involving gas-solid reactions at elevated temperatures. Some types of Iron ore are weak in magnetic properties. Hematite, goethite and limonite are classified in this group. Unlike magnetite, which shows strong magnetic susceptibility, these ores are hard to beneficiate through magnetic separation route. Many researches have focused on gravity separation and flotation routes for upgrading these ores and these methods have also been utilised in the industry. One of the methods to whose industrial application less attention has been paid is magnetising roasting in which the non-magnetic iron ore is transformed to magnetite which is further beneficiated through magnetic separation. In this study, magnetising roasting tests have been performed on one goethite sample in order to check the feasibility of using this method for this specific ore in industrial scale. It is worth mentioning that high intensity magnetic separation have been performed on this sample before but the achieved results were not promising. Results have revealed that through magnetising roasting magnetite content of the ore could be increased from 1.7 per cent up to about 25 per cent. FeO content of the feed sample was increased from 1.03 per cent up to around 9.25 per cent. Also optimum size distribution for achieving the best results in magnetising roasting for this sample has been determined through this study. The best results were achieved when the ore size was 0–10 mm. The effect of coal ratio, time and temperature on the process have also be studied. A coal ratio of 5 per cent, time of 30 min and a temperature of 850°C were determined to be the optimum conditions. Finally, the technical feasibility of utilising magnetising roasting for this specific ore has been confirmed.

Aug 24, 2022

Rio Tinto Iron Ore (RTIO) manages eleven mines in the Pilbara region, Western Australia. Three of these mines have previously or are currently mining black shale that contains varying amounts of pyrite. Several new deposits currently being evaluated and existing mines that may progress below water table in the future, will also encounter this waste material. The black shale presents not just an acid rock drainage risk but also a spontaneous combustion risk. This paper presents the black shale management strategy and provides an overview of the relevant activities undertaken by RTIO. The strategy can be divided into two components which firstly involve defining the risk and secondly involve managing the risk. The mineral waste management plan is used to identify specific mineral waste hazards by:geochemical characterisation of waste material,undertaking mine site specific risk assessments,characterising the receiving environment,identifying sulfidic boundaries in geological and mining models,quantifying the amount of sulfidic material in medium and long-term mine plans, anddesigning and sequencing black shale waste dumps. Once a mine exposes black shale the Spontaneous Combustion and Acid Rock Drainage management plan is used and the major activities are: regular site meetings with a representative from every group that works with black shale;compliance with safe working procedures for site specific and detailed activities;regular training;the use of specific explosives to prevent premature detonation;ongoing geochemical characterisation;acid water management, monitoring and analysis;regular internal and external auditing of procedures and practices; andclosure planning assessments and preparations (ie cover trials, geochemical void modelling, geochemical waste dump modelling). The success of this holistic strategy is evident by the awareness of personnel within the business, thorough understanding of the geochemistry and by undertaking proactive management of black shale during mining. The strategy and management plans adopted by Rio Tinto Iron Ore have activities that other mine sites with potentially acid forming material may like to consider implementing.

Jan 1, 2009

The theme of my address to your Institute, indeed its name, is "The Mineral Industry - What Next?" Knowing that I was required to make four appearances, and not wanting to be too repetitious, I wrote a rather long speech of which I will deliver various sections at different places, with a common introduction. Specific areas I have addressed are "Exploration", "New sources of minerals and energy", and "Mining and metallurgy of the future".

Jan 1, 1984

By Szymanski J

Although efforts towards producing a `total quality rockfill product' have allowed cemented rockfill costs to be reduced considerably, there is still tremendous potential for further cost reductions. Cemented rockfill costs range from approximately $7 to $12 (US) per tonne of fill placed. Approximately 50 per cent of the rockfill costs are associated with cement costs. A large portion of the remaining 50 per cent is associated with labour and materials handling costs. Several Canadian underground mines utilise haulage trucks and/or conventional belt conveyors to distribute the rockfill. However, due to the restrictive nature of the underground environment, these current materials handling systems have limitations (ie spillage from trucks, dust from conveyors). The Sicon conveyor system (developed in Sweden) has considerable potential for replacing these current methods. The Sicon conveyor utilises a revolutionary approach - the conveyor belt is folded over upon itself (forming a tear drop shape) so that the transported material is completely encased within the belt. The Sicon conveyor's ability to negotiate very tight comers (without transfer points) makes the conveyor very appealing for underground mining applications. An analysis comparing the pros and cons associated with the Sicon conveyor system versus conventional materials handling systems will be presented in this paper.

Jan 1, 1995

The Que River and Hellyer polymetallic massive sulphide ore bodies are located 3 kilometres apart in the Cambrian Mount Read volcanics of Western Tasmania. Both deposits are classic examples of the Kuroko volcanogenic style. Base and precious metal rich hydrothermal solutions rose through a deep fracture system and vented on the sea floor, causing sulphides to accumu- late in adjacent topographic lows. Together the preproduction geological resource is approximately 23 million tonnes at greater than 18% zinc plus lead, with economically significant silver and gold. Exploration by Aberfoyle in the Mount Read volcanics com- menced in 1970. Que River was discovered in 1973 following a comprehensive data review, a regional stream geochemical survey and a helicopter-borne electromagnetic survey. Production began in 1981, and the mine is currently producing 300,000 tonnes per year. The ore is sold to the Electrolytic Zinc Company of Aus- tralasia Ltd mill at Rosebery. Ten years of extensive geological mapping, soil geochemistry, and induced polarisation, combined with continual study of the Que River orebody and its host rocks, formed a strong frame- work for the discovery of the Hellyer deposit, which was found as a result of drilling .a subtle time domain electromagnetic anomaly in 1983. Hellyer is currently being mined at a rate of 250,000 tonnes per year, with the ore being concentrated at Aber- foyle's converted Cleveland tin mill. Treatment of 1 million tonnes per year will begin in early 1989 at a new mill located near the Hellyer site.

Jan 1, 1988

By Lama R. D

The Australian underground coal mining industry is undergoing major changes. This paper analyses the technologies presently being researched in mines, and discusses their utilisation as major contributors in the underground mining of coal in Australia over the next 20 years. It describes the problems that underground mining of the year 2000 will face and the possible solutions to those problems based upon results of present day research. Methods, equipment and organisational requirements are outlined. Developments in micro-electronics, computerisation and monitoring will require a new look into human resource development, education and training, and organisation to meet the challenges of the 21st century. The mining system's philosophies of the future are Outlined.

Jan 1, 1986

The Nickel Rim Depth Cu-Ni-PGE deposit, discovered by Falconbridge Limited in 1993, illustrates several trends in exploration in the Sudbury area. Recent discoveries tend to be deep, high grade, footwall hosted, close to or straddle property boundaries and made using a multi-disciplinarian exploration approach that integrates economic considerations with geology, metal geochemistry and geophysics (borehole EM). The Nickel Rim deposit occurs down dip of Inco's Victor Deep deposit (4.2 million tonnes at 2.25 per cent Ni, 7.30 per cent Cu) in the eastern margin of the Sudbury Igneous Complex (SIC) at a depth of 2650 m. Before commencing drilling an economic evaluation was done to determine the minimum size needed to be economic at the expected depths and determine the expected value of an exploration venture. The subsequent surface exploration program discovered a drill indicated, undiluted mineral inventory of 1.6 million tonnes of 1.58 per cent Ni, 10.13 per cent Cu, 4.17g/t Pt and 3.50 g/t Pd including 519 000 tonnes of 4.13 per cent Ni, 25.53 per cent Cu, 9.76 g/t Pt and 8.42 g/t Pd. The deposit is hosted by gneiss, migmatite, gabbro and pseudotachylite (Sudbury Breccia) 100 m below the base of the SIC.

Jan 1, 1996

A mineral exploration manager's prime function is to provide a frame- work within which new mine production can be achieved. As part of this framework, the manager should know his employerb future requirements, and should direct exploration towards those particular mineral commodities which indicate satisfactory growth in consumption and price. Selection of these commodities can be assisted by studies of world reserves, and long term trends in price and consumption. Exploration planning is most efficient with an assured and reasonably uniform supply of funds.

Jan 1, 1980

Geological hazards such as faulting, basement ridges, and zones of "thin" (

Jan 1, 1998