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Three methods of gold analysis are briefly described highlighting some of the problems and advantages of each. The variation of results between samples and splits and due to method preparation are illustrated. The mean percent difference of the fire assay values from the means of sample split values for three cases is 15%. Finally, a comparison of the aqua regia atomic absorption spectroscopy and fire assay fusion AAS techniques is made. This shows that the mean precision, the ability to obtain the same value, of the methods at 98% confidence are +30% and +15% respectively. The fire assay fusion atomic absorption spectroscopy method is relatively more accurate than the aqua regia method.

Jan 1, 1982

By Smith KS

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralized areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado, has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles (1) could have been better utilized to first predict and minimize the environmental problems, and (2) can now be used to optimize the environmental cleanup.

Jan 1, 1995

Access to land for exploration, development and mining purposes is extremely critical to the viability of the mining industry and subsequently the well being of society.The mining industry has been subject to environmental controls and considerations for the past 20 years. Today there is greater land use competition and more debate as to its use. To retain reasonable access the mining industry must comply with the rules and regulations by which it is governed.A new set of rules and regulations have been approved for use in Queensland, known as the Mineral Resources Act 1989. This Act clearly outlines the titles available and the requirements to obtain access.There are three main titles of interest to mining companies. These are an Exploration Permit, Mineral Development Licence and a Mining Lease.The Exploration Permit (EP) is for exploration purposes. Applications for EP's are assessed on their content and past performances. An EP is granted subject to a security deposit and conditions. Prior to entry the EP holder is required to inform the land owner of the proposed activities and times of entry.

Jan 1, 1990

By K McNabb, M H. Turner, P A. Jenkin

Mining of the Agnew nickel deposit commenced in 1970 using a variety of underground mining methods, though with mixed success due to the difficult ground conditions. WMC Resources Ltd acquired the operation in 1989, and commenced nickel production with an open pit. In 1995 all production reverted to the rejuvenated underground mine, using exclusively SLC (sublevel caving) methods. Currently the mine produces 1.4 Mt per annum, at an average grade of 1.74 per cent Ni. Underground mining of the Perseverance orebody has always presented significant challenges due to the difficult ground conditions in the weak and altered ultramafic rocks. The range of problems include areas of swelling minerals, intense and extremely weak shear zones, relatively high in situ stress, and in other areas very brittle rocks. Under these conditions rock mechanics input has been and remains a critical element of the mining strategy. Severe ground behaviour difficulties down to a depth of 500 m below surface prompted a review of the mining strategy for the large disseminated nickel orebody, including evaluation of alternative mining methods. However, sublevel caving was ultimately selected as the preferred method, and a re-design of the SLC cross-cut layout followed. A selection of rock mechanics investigations of interest are described, including complex virgin stress measurements, detailed ground behaviour monitoring, and the use of non-linear stress analyses to re-design the mine layout. Subsequent ground behaviour, support design and production scheduling are also described.

Jan 1, 2000

In the past few years the Rietveld method emerged as a routine tool for quantitative phase analysis (QPA) from X-ray diffraction data. Fast and reliable results became possible by combining modern computer technology and optimised mathematical algorithms with the fundamental parameters approach in the Bruker AXS TOPAS software. Here the routine analysis of bauxite raw material and of aluminium bath electrolyte is presented. The accuracy of bauxite quantification was tested by analysing the IUCr round robin sample. An agreement of better than one per cent was obtained for minor constituents and a maximum deviation of 2.5 per cent for the major phases. This is excellent agreement with expected results from weighting. Ten different phases were quantified in natural samples from Turkey with a precision better 0.5 per cent for the major phases and one per cent for the minor phases. Additionally, crystallite sizes were obtained from the peak profiles that give valuable information for the processability of the material. XRD data from solidified aluminium electrolytes were rapidly measured using silicon strip detector technology. With the LynxEyeTM detector full patterns were collected in 90 seconds and analysed with TOPAS. It is shown how to derive well-established measures such as bath ratio and excess AlF3 from the Rietveld results. These measures are widely used in aluminium production and readily available with very high precision. The excellent agreement with ALCAN reference data demonstrates the outstanding accuracy of the method. The mean deviation between here presented results and reference data is below 0.5 per cent for total CaF2, below 0.25 per cent for excess AlF3 and 0.02 for the bath ratio. The precision of the method was evaluated by repeated measurements.

Jan 1, 2008

By Mauk JL, McOnie A, Simmons SF

Three cross sections, 200 m apart, display the distribution of indicator hydrothermal minerals across the Empire zone of the Golden Cross epithermal Au-Ag deposit, Waihi, New Zealand. These minerals are used to interpret the temperature and composition of hydrothermal fluids. The distribution of interstratified illite-montmorillonite and illite indicate that temperatures ranged from 140 to >220¦C, with temperatures above 220¦C predominating. The mineral assemblage of quartz-adularia-chlorite-illite-calcite-pyrite envelops the Empire vein system and stockwork, and reflects formation from an alkali chloride water, whereas the mineral assemblage of replacement calcite-interstratified illite - montmorillonite- kaolinite forms a carapace and reflects formation from a C02-rich steam-heated water. Alkali chloride waters appear responsible for the epithermal Au-Ag mineralisation.

Jan 1, 1995

By P Waters, S Miller

BHPBilliton operates the Mt Whaleback Mine located in the semi-arid Pilbara Region of Western Australia. Approximately 200 Mt of net acid generating (NAG) material still remains to be mined. Acid Rock Drainage (ARD) was first identified at the site in 1995 following cyclonic storms. This resulted in the development of strategies that have allowed the mine to successfully manage ARD whilst continuing to operate. BHPBilliton Iron Ore is working toward prevention of ARD in its operations, however, historical practices have left residual areas that must be considered. Three significant sources of ARD have been identified that must be managed: stormwater run-off from exposed pyritic shales in pit surfaces; basal flows beneath overburden storage areas following rainfall events; and contaminated water from pit dewatering. The mine contains all ARD water onsite. This is achieved by: storage of all affected water in the ARD dam; evaporation of affected water from the ARD dam and the adjacent evaporation ponds; pumping from upstream dams to prevent stormwater from being affected; and emergency storage and treatment in-pit as a contingency. The site ARD management strategy is approved by senior management and endorsed by State Government regulatory authorities and relevant external stakeholders. Additional strategies are also under evaluation to effect long-term closure of the operation. Record rainfalls from 1998 - 2001 have tested the capabilities of the ARD strategy and management plan. Learnings from these events, coupled with recommendations from an extensive technical audit in 2000, have been incorporated into the strategy for ARD management. This paper presents the strategy and an overview of the ARD management plan that can be considered and applied by other affected sites in the management of ARD.

Jan 1, 2003

Sample preparation for gold samples, where the distribution and size of gold particles is often irregular, usually demands that a relatively large sample weight is taken to produce a representative sample for analysis. Traditional sample preparation of gold samples incorporated multiple stages of coarse particle size reduction followed by subdivision of the sample prior to final fine pulverising. This technique developed because of the limited equipment options available to laboratories. As a result significant errors are introduced and the final sample size being pulverised is a small fraction of the original sample weight. Three significant developments have occurred in the last 25 years to significantly improve sample preparation of gold samples: 1.  large capacity fine pulverising,2.  fine jaw crushing, and3.  whole sample coarse pulverising. In the mid-1980s an Australian manufacturer developed large capacity pulverising bowls which had the ability to reduce samples with a mass of 1.5 - 3.5 kg to a nominal 0.075 mm product in approximately three to five minutes. Laboratories were able to produce a large homogeneous pulverised sample which significantly reduced the error in sampling. However, exploration and mine samples are usually 7 to 10 kg and the sample requires a subdivision stage following crushing to produce the 3.5 kg for the pulverising step, thus introducing potential for significant error. The development of fine jaw crushing allowed particle size reduction to -2 mm which reduced the subdivision error of the bulk sample prior to fine pulverising. Subdivision of the crushed sample at -2 mm still results in potential sampling errors, where the gold particles are not sufficiently liberated to be representatively sampled. Clearly the best option would be to reduce the particle size small enough to ensure a representative sample prior to final pulverising. Continuous mills offer a partial solution but are relatively slow and subject the sample to differential pulverising prior to subdivision. Clearly this does not provide the best solution for routine laboratory applications where high volumes of samples are to be processed. The recent development of a large capacity coarse pulverising system allows samples of up to 10 kg to be reduced to -0.25 mm prior to subdivision, and fine pulverised to -0.075 mm. Laboratories now have the necessary equipment to perform reliable large capacity sample preparation of gold samples. The exact choice of a sample preparation scheme may still depend on particular ore types but the need for multiple crushing and subdivision stages is redundant.

Jan 1, 2008

By M Heidari, M Ataei

Today, the selection of a mining method is a multi-criteria decisionmaking process, with many factors in this process connected to each other. These trends do not have a high degree of confidence. In this study the analytical hierarchy process was used to select the suitable mining method for anomaly No 3 of Gol-Gohar iron mine of Iran. The results of this study show that gathering all existing information from the exploration stages and using AHP technique, the open pit mining method is the mining method for this anomaly.

Jan 1, 2003

There are two main challenges in analysis of spectral data: to output as accurate an interpretation of the sample mineral assemblage as possible and to then use the spectral data to map out trends (downhole, across section or traverse) that will assist the exploration geologist to target drilling and further exploration. This paper will discuss methods of extracting the maximum amount of information from spectral data and examples of plotting the information downhole, in section and plan view to assist in exploration and mining. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Waijun Cheng, Guilin Xie

A microcomputer control system prototype of a Switched Reluctance drive for storage battery electric vehicle in coal mines is developed. The paper introduces the hardware components, the control strategy and the software unit. It is shown that

Jan 1, 1998

By G W. Wilson, C Panidis

Potentially acid forming (PAF) waste rock contained in dumps formed as a result of open cut mining of metalliferous orebodies are conventionally sealed or covered using a near-saturated, low permeability compacted clay layer, protected with a mulch layer and/or vegetated growth medium. The purpose of the compacted clay layer is to limit oxygen diffusion and the infiltration of rainfall into the dump. Where the aerial extent of the PAF waste rock dump is large, or where suitable clayey material is in short supply, it may be difficult to source sufficient suitable clayey material to form the cover. The paper describes a laboratory-based investigation of combining inert waste rock and tailings to form an alternative seal or cover material. The inert waste rock was sourced from the trafficked surface of a non-acid forming (NAF) waste rock dump, with a maximum particle size of about 100 mm. This was combined with NAF thickener underflow tailings slurry in various mass ratios, and the resulting mixtures tested for their particle size distribution, compaction characteristics, soil water characteristics (relationship between suction and volumetric moisture content), and saturated hydraulic conductivity. The mixtures tested ranged in consistency from those dry enough to be compactable, to those with the consistency of wet concrete that lend themselves to placement without the need for compaction. The laboratory test results showed that the suitability of the mixtures as seal or cover materials is very dependent on the particle size distribution of the mixture, with well-graded mixtures having substantial fines performing best.

Jan 1, 2003

By Mules GJ

Geotechnical investigations have played a key role in influencing decisions for development of the Porgera Gold Project in the highlands of Papua New Guinea. Porgera is located 130 km west-northwest of Mt. Hagen in steep mountainous terrain with high rainfall. Much of the site is underlain by weak mudstone of the Chim Formation and creeping colluvial soils. Landsliding is common on the steeper slopes and in the valley floors. Structures have had to be sited to avoid areas susceptible to these movements. Early stage feasibility investigations included studies of tailings dam and waste rock dump sites, processing plant sites and hydroelectriic schemes. Further studies, leading into the design stage included the Enga Highway upgrading, water supply and power supply schemes. As construction for the project proceeds geotechnical input remains at a high level, with emphasis now on maintaining viable stable sites and refining data on which designs were based.

Jan 1, 1990

The authors are looking at the behaviour of the mineral processing circuits by means of the simulators operating under random disturbance. The present paper deals with the fuzzy control systems in comparison with PID controllers. A series of tests are conducted on simplified prototype processes with (1) dead time plus first-order lag model and (2) diffusive model. In the next series of tests the self-sustained process model was introduced to improve control against dead time. In both cases fuzzy and PID controllers are optimised by EVOP method. Particular attention is paid to the effect of observation noise to analyse for the problems which can be fatal to practical applications in mineral processing. Finally the methods developed are applied to a closed-circuit wet grinding system simulator operating under random disturbance.

Jan 1, 1993

The Yilgarn Block of Western Australia presents (figure 1) a number of problems for conventional diamond exploration based on heavy indicator mineral sampling. These problems are due to the geology and unique geomorphological development of the Yilgarn Block.Essentially the Yilgarn Block is a pene- plain developed on a craton composed of Archaean intrusive granitoid rocks with meta- morphosed greenstone; which, apart from regional uplift, has not been tectonically disturbed since planation by glaciation in the Permian. Therefore since the early Plesozoic the Yilgarn Block has been subjected to terres- trial weathering conditions. Bettany et al., (1984) identify two phases of particular importance in the development of the present landforms: 1. Periods of lateritization during the Tertiary which result in the ~lassi~al laterite profile (figure 2). Duricrust indurated : Fe and Al oxides Mottled zone : Clay and Fe oxides Saprolite or pallid zone : leached clay grading into fresh rock. 2. Subsequent periods of aridity and semi- aridity during which laterite development was truncated and reworking of laterite Occurred.

Jan 1, 1988

By B Ekberg, R Salmimies, T Kinnarinen, A HSkkinen

The regeneration of the ceramic filter medium used in iron ore dewatering is often done by combining backwashing, ultrasonic cleaning and chemical regeneration. Of these three, the first two are applied more frequently, whereas chemical regeneration is done only when needed, eg once a day. Chemical regeneration of the ceramic filter medium in iron ore processing can involve the use of oxalic acid to dissolve the iron oxide particles. Even while performing simple chemical regeneration, meaning no ultrasound to assist the cleaning, the changes in the performance and in the structure of the filter medium could not be explained solely based on the dissolution or the removal of particles from the surface. Good regeneration results were obtained at 35 and 50¦C, meaning that the final permeability of the filter medium corresponded to that of unused filter medium. Permeability of the medium after regeneration at 15¦C was also good after 12 h, but did fall short of those regenerated at higher temperatures. Changing the acid concentration did not seem to have a significant effect on the regeneration.CITATION:Salmimies, R, Kinnarinen, T, Ekberg, B and HSkkinen, A, 2013. Particle dissolution in the chemical regeneration of the ceramic filter medium used for magnetite dewatering, in Proceedings Iron Ore 2013 , pp 473-478 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The Drummond Basin is a large intracratonic basin which developed in central Queensland during Late Devonian to Early Carboniferous times. It is postulated that the Drummond Basin developed as a foreland basin, to the west of a probable west dipping continental margin volcanic arc and subduction zone. The Drummond Basin sequence has been s,ibdivided into three tectono-sedirnentary cycles. Cycle I forms the base of the sequence and comprises thick sequences of intermediate to felsic volcanics and proximal volcanolithic sediments. The volcanics, particularly in the northeast of the basin, occur in separate sub-basins around what were probably isolated eruptive centres. In contrast, the rocks of Cycle 2 and Cycle 3 have been deposited during episodes of broad, basin wide subsidence. Five major igneous episodes, some of which may be co-magmatic, are recorded in the eastern Drummond Basin and environs between the Late Devonian and the Early Permian. The first and second episodes occurred during the Late Devonian to Early Carboniferous and are represented by the volcanics in Cycle 1 and Cycle 3. The third episode involves the intrusion of granitoids of Early Carboniferous age into the Drummond Basin sequence. These occur in the Ukalunda area and are related to gold mineralisation at Ukalunda and Valhalla. Episode four includes the felsic volcanics of the Bulgonunna Volcanics. This episode does not appear to he broadly auriferous but gold mineralisation does occur in possible basal Bulgonunna Volcanics at Mount Coolon. The final episode includes a suite of granitic intrusives which intrude the Bulgonunna Volcanics and which are considered to be co-magmatic with them. These intrusives do not appear to be generally associated with gold mineralisation. Gold mineralisation is widespread in the north- eastern Drummond Basin and environs. It is probable that the gold mineralisation is concentrated in epithermal cells during the Late Devonian to Early Carboniferous volcanic cycles. This style of mineralisation appears to be related to tectonic setting in modern analogues.

Jan 1, 1989

By J, J M. Young, P T. Nielsen, R Zhu

Improved understanding of the variables that influence hydrocyclone performance is of increasing interest to the iron ore industry, where hydorcyclones are widely used to deslime fine ore. In many cases, the impact of particular variables is not quantified sufficiently well experimentally to ensure that industrial performance will match expectations. The current work focused on developing and implementing a systematic methodology to evaluate and compare the performance of four different hydrocyclones in a desliming application. A critical component of the project was the design and construction of a pilot-scale hydrocyclone rig using state of the art monitoring and sampling methods. A wide ranging test programme was conducted to quantify the effect on metallurgical performance of the key hydrocyclone variables such as pressure, feed density, vortex finder size, spigot size and hydrocyclone make/overall design. Details of the experimental approach are presented, along with a discussion of the sizing analysis methods used. Performance criteria were established to assess the four hydrocyclones. The effects of each major variable were quantified over a wide range of conditions. The results show that clear performance differentiation was achieved, enabling the selection of the optimum configuration. The results from this work demonstrate the benefit of objectively assessing the performance of nominally equivalent units in selecting an optimum configuration that best satisfies the performance criteria.

Jan 1, 2002

The paper discusses how automation is steadily proceeding throughout all areas of the electrolytic zinc industry. Fluid bed roasters with integral sulphuric acid plants are now on -computer control. Highly efficient, continuous leaching and purification stages, with feed-forward predictive and optimisation computer control, precede electrolytic cells with on-stream solution analysers and automatic stripping of deposited zinc. Controlled electric induction furnaces feed continuous casting lines, equipped with automatic stacking and strapping, machines, after computer based metal analysis has confirmed metal purity or alloy composition. The paper also discusses the use of computer models tied to process control systems, and the equipment and solution measurements that could be automated with advantage, using modern micro-based controllers and analysers.

Jan 1, 1985

By K Inoue

The pressure oxidation of molybdenite concentrates in acidic and alkaline media has been studied. The conditions of the selective oxidation of copper and iron sulphide minerals with a quantitative copper leaching by ferrous-ferric-sulphate solution have been found and explained from the point of view of electrochemical kinetics. The partly oxidised residue consisting of molybdenite and (hydro-) oxide of iron (III) was then decomposed by oxygen in alkaline media. Effects of the main parameters, such us oxygen pressure, leaching temperature, solid-liquid phase ratio, autoclave stirring speed as well as lixiviants nature on the molybdenite oxidation rate have been established.

Jan 1, 2000