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By E J. Y Koh, G J. McLachlan, E Amini, N Beaton

Preconcentration greatly reduces the ore mass input to the processing plant while upgrading the grade. One of the commonly used methods of preconcentration is optical sorting. These methods rely on optical sensors which classify the material stream into “accept-reject” streams. Currently, it is common to use near infrared (NIR) or colour cameras to classify streams based on reflectance or colour thresholds set by experts. The imaging is done through line-scan sensors where the material is scanned on a belt or a chute. Then, a separation apparatus like a diverter gate or air jet is controlled to separate the streams according to the classification made by the algorithm. Separation efficiency is dependent on the classification algorithm. Existing classification algorithms rely on low-level feature discrimination like observing individual pixel values for reflectance or colour hues. This limits discrimination between minerals with low contrast in colour. Human experts perform mineral segmentation using texture, colour distribution and shape, but it is difficult to translate these visual rules to mathematical thresholds. Deep learning methods like Convolutional Neural Networks (CNNs) provide high-level feature discrimination similar to a human expert. Instead of relying on pre-defined features, the CNNs learn complex features from the dataset. CNNs can construct a hierarchy of features based on pixel clusters to learn texture, shapes, and colour spectrums of the mineral grain surface to provide better separation. In this study, a state-of-the-art deep learning instance segmentation method is used to outline boundaries and classify grains from the background (mineral segmentation). The algorithm is trained on images collected from a flotation feed of a gold deposit, where the gold is mechanically locked inside pyrite. This method can process on-line video inputs at 5 frames per second to provide a live grade. The proposed method is inexpensive as it only uses a camera and a desktop computer.

Nov 10, 2020

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 T W. C Stambolie

Coalmines, like any other mine, generally involve the classic three-staged approach to mining studies; namely concept, pre-feasibility study (PFS) and feasibility studies (Cusworth, 2012). Subsequent to these studies, and in instances parallel to these studies, the commitment to an environmental impact statement (EIS) is made in order to secure both state and federal development consent. In recent times, the sentiment to both mining and coal is changing whereby the traditional approaches to mine planning and economic evaluation is complicated by evolving environmental legislation, expectations and time frames. It is all too common to take shortcuts in the development of projects in order to create the perception of cost savings and expediting the delivery timeline. Atkins (2016) points out that: boards of so many small to mid-tier mining companies, and a few majors, focus on relentless project delivery too early in the project process, with so little time and effort applied to risk analysis and option development. Unforeseen risks can cost any timeline or budget far more than the effort required assessing and mitigating these. The ultimate risk to any feasible coal project is that of environmental approval and achieving development consent.CITATION:Stambolie, T W C, 2016. A black canvas – planning a greenfield coalmine in New South Wales, in Proceedings Life-of-Mine 2016 Conference , pp 31–35 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By R O. Laidlaw, J L. Mauk

The Coeur d'Alene mining district in northern Idaho, USA is the second largest producer of silver in the world. Mesothermal silver-lead-zinc veins occur in the metasedimentary rocks of the Belt Supergroup with five main types of associated hydrothermal alteration: 1) feldspar destruction, 2) hydrothermal bleaching, 3) carbonatisation, 4) sulfidation, and 5) silicification. Hydrothermal bleaching is characterised by hematite destruction with associated siderite and quartz veins and veinlets, coarse euhedral pyrite and magnetite. Bleached zones envelop both mineralised and barren veins and extend for metres to tens of metres into the wall rocks. Carbonatisation consists of addition of siderite, which occurs as veins, veinlets, stockwork, irregular blebs or spots, and coarsely disseminated grains, depending on the relative distance from the main vein structure. Siderite envelops nearly all mineralised veins, relates to all other alteration types and extends from several metres to tens of metres into the wall rocks. Pyrite and galena alteration dominate sulfidation and are associated with some mineralised veins. Pyrite alteration strongly correlates with siderite alteration and exists in three main forms: a) very fine-grained pyrite flooding, which can extend for metres to tens of metres into wall rocks; b) coarse-grained, euhedral pyrite, which is sporadic and associated with the redox boundary in hydrothermally bleached zones; and c) small isolated zones (6 - 15 cm) of medium-grained, subhedral to euhedral pyrite associated with pervasive siderite alteration. Where present, disseminated galena extends for metres to tens of metres into the wall rocks. Silicification is characterised by veins, veinlets, stringers, irregular patches and variable hardness in siltites and commonly appears in association with hydrothermal bleaching and siderite alteration. Although related to mineralisation, silicification is sporadic and in most places a clear envelope around mineralised veins cannot be identified.

Jan 1, 2001

By K Orth

The volcanic successions that host massive sulphide deposits are diverse in composition, facies types and facies relationships. They also show a variety of spatial and temporal relationships to mineralisation. In many examples, such as the Koongie Park Formation in Western Australia, the host succession includes more or less conformable syn-volcanic sills with peperitic contacts. Such sills can be an important source of heat for fluid circulation, influencing patterns of hydrothermal alteration and the location of co-eval and later mineralisation. The impact of syn-volcanic sills on the host succession depends in part on the initial porosity and permeability of the enclosing facies. The special properties of glassy pumice û being highly porous, permeable, and reactive û allow pumice-rich facies to preferentially focus hydrothermal fluid flow. However, the same properties promote early alteration and porosity reduction. Hence, the diagenetic and compaction history of pumiceous facies strongly influences their potential to host massive sulphide mineralisation. In contrast to pumice, dense glass has relatively low porosity, at least initially, and does not compact. Non-vesicular glass is a major component of submarine lavas, syn-volcanic intrusions and some volcaniclastic facies. However, especially in submarine settings, dense glass is commonly intensely perlitically fractured soon after eruption. The fractures greatly increase the porosity and permeability, locally accelerating diagenetic and hydrothermal alteration. In addition to false pyroclastic textures, altered perlite may exhibit false porphyritic textures. Silica- or feldspar-altered perlite kernels surrounded by intensely altered phyllosilicate domains can resemble phenocrysts in a fine grained groundmass.

Jan 1, 1999

By Tuite M. J, Woolcock L. J

The Awak Mas gold project is located in the Province of South Sulawesi, Republic of Indonesia. It is situated 300 km by road north of the provincial capital of Ujung Pandang. The capital is readily accessible by air from Australia via Denpasar on Bali or the Indonesian capital, Jakarta (Figure 1). Elevations at Awak Mas range from 850 to 1400 metres above sea level in reasonably rugged terrain. The area is covered by primary and secondary (regrowth) rain forest. The region is subject to an equatorial-type tropical climate. The annual rainfall is a high 3000 mm most of which falls in the rainy season between March and June. In the lower valleys rice, cloves and chocolate crops are cultivated. Title to the project area is secured by a Contract of Work (COW) issued to PT Masmindo Eka Sakti (MES) on 23 October 1987 by the Government of Indonesia. MES was controlled at the time by New Hope Industries group of Brisbane. After New Hope had completed initial reconnaissance exploration of the area, Battle Mountain Gold Company (BMGC) farmed-in in 1991 and earned a 60 per cent beneficial interest in MES.

Jan 1, 1996

By G Yeowart, P D. Munro

The Prominent Hill copper-gold concentrator of OZ Minerals Limited in South Australia was built in 2008 and commenced commercial production in early 2009. It has a design ore throughput of eight million tonnes per year (Mt/yr). While the flow sheet has many items in common with other plants treating ores from iron oxide-hosted copper-gold deposits, the Prominent Hill concentrator also has some unique features. Plant design has been based on a 'template' of the very successful Ernest Henry concentrator. Initial options considered for processing Prominent Hill copper-gold ore are briefly examined as well as potential complications arising from the presence of a considerable tonnage of 'gold-only' material present in the deposit. Metallurgical test work and the subsequent decisions leading to the selection of a conventional crushing, semi-autogenous grinding (SAG) and rougher flotation circuit is discussed. One particular difference with other plants treating this ore type is that metallurgical tests and mineralogical studies identified that rougher concentrate had to be reground to a P80 of 20 - 25 microns or finer for adequate liberation of fluorine-bearing minerals. Subsequent satisfactory separation of fluorine-rich gangue material from the valuable copper sulfides requires highly efficient cleaner flotation to make a commercial quality copper-gold concentrate. Xstrata Technology's IsaMillÖ and Jameson Cell technologies developed to meet similar taxing fine grinding and flotation duties for the treatment of the refractory zinc-lead-silver ores of the Carpentaria-Mount Isa Mineral Province were selected for regrinding and cleaner flotation. Plant design has features aiding ergonomics for ease of operation and maintenance not commonly seen in recent projects with large sulfide flotation concentrators.

Jan 1, 2009

Remnants of Plio-Pleistocene hot spring systems in Northland, New Zealand contain sulfide minerals, principally pyrite, marcasite and cinnabar. The climate is warm temperate to subtropical, with up to 3 m of rainfall per annum, and rocks are deeply weathered. Decomposition of the iron sulfides in natural outcrops and human excavations results in acid rock drainage with pH typically between 2 and 5, and locally down to pH 1. Deeply weathered basement greywacke is clay-rich and has negligible neutralisation capacity. Some overlying volcanic flows have resisted weathering, and pH is kept near neutral by relict secondary calcite in small areas. Natural rainforest soils commonly have pH between 4 and 5 over mineralised and unmineralised greywacke. Mineralised zones are enriched in arsenic, which occurs in solid solution (up to 1 wt per cent) in sulfides and phosphate minerals. Mercury also occurs in solid solution in some of these minerals, as well as in cinnabar. Base metals are present in low (background) concentrations only. Decomposition of the iron sulfides and phosphates releases the solid solution arsenic and mercury into the acid rock drainage solutions. Arsenic is readily adsorbed on to iron oxyhydroxides formed in acid rock drainage situations, and can be effectively removed from the biosphere. However, this arsenic is released back into the environment if the pH rises, as adsorbed oxyanions become less strongly bound and are displaced by hydroxyl ions. Behaviour of dissolved mercury is similar to that of arsenic but less well understood in these settings. Both arsenic and mercury are readily leached into pH 6 solutions from solid material collected from acid rock drainage sites. These observations suggest that neutralisation of acid rock drainage sites is undesirable in this setting, as arsenic and mercury will become more mobile in the environment. The naturally low pH of 4 to 5 of the forest floor, or even lower pH of natural acid rock drainage, is a preferable management option.

Jan 1, 2003

By Woodcock JT

This paper deals with some innovations and current proposals for the treatment of gold ores and considers the possibilities of incorporating new developments in new or revised ore treatment flowsheets. The main topics considered are I. typical practice in relation to the size of gold particles, 2. concentration of coarse gold, 3. leaching reagents, 4. in situ leaching, 5. heap leaching, 6. carbon-in-pulp adsorption, and 7. treatment of complex ores (gold in pyrite, gold tellurides, and carbon-containing ores).

Jan 1, 1982

By Davey P. T, Tsambourakis G

Mineralogical analysis of supergene sulphide ore recovered from areas close to the underground workings at the abandoned Mutooroo (South Australia) mine shows that the original sulphide minerals have undergone substantial alteration. The cause of this alteration is believed to be contact with the highly saline, acidic mine water. The copper is now present as a sulphide that can best be described as a copper- and iron-delicient chalcopyrite, CuxFeyS2, where in most cases x < y. The values of x and y vary from point-to-point within each grain.Leach tests under a variety of conditions show that dissolution of the copper from the supergene sulphide ore can be readily achieved, particularly when compared with the behaviour of Mt Isa chalcopyrite concentrate. For the supergene sulphide ore, an increase in the acidity and the iron(lll) concentration of the leachant re ults in an increase in the rate of copper dissolution.The results are briefly discussed in terms of the experimental in-situ leaching operation at Mutooroo, South Australia.

Jan 1, 1986

By C Mark

Coal bursts involve the sudden, violent ejection of coal or rock into the mine workings. They are a particular hazard because they typically occur without warning. During the past two years, three US coal miners were killed in two coal bursts, following a six-year period during which there were zero burst fatalities.This paper puts the US experience in the context of worldwide research into coal bursts. It focuses on two major longwall mining coalfields that have struggled with bursts for decades. The Utah experience displays many of the ‘classic’ burst characteristics, including deep cover, strong roof and floor rock, and a direct association between bursts and mining activity. In Colorado, the longwalls of the North Fork Valley (NFV) also work at great depth, but their roof and floor strengths are moderate, and most bursts have occurred during entry development or in headgates, bleeders or other outbye locations. The NFV bursts also are more likely to be associated with geologic structures and large magnitude seismic events. The paper closes with a brief discussion of how US longwalls have managed the burst risk.CITATION:Mark, C, 2014. Coal bursts in the deep longwall mines of the United States, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 33–40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By C F. Nichol, L Smith, R D. Beckie

A better understanding of the hydrogeology within mine waste rock and cover systems is essential for the quantification, prediction and prevention of metals loading to the environment surrounding waste rock piles. The effect of surface condition on the internal flow mechanisms within an intermediate-scale constructed waste rock pile is being investigated at the Cluff Lake Mine, Saskatchewan. Changes in the water balance, the outflow distribution and water residence time have been observed in the waste rock pile following successive modifications of the surface condition. The three year old, run of mine, free-dumped surface was ripped to a depth of 30 cm to 40 cm, and levelled in October of 2001. In August 2002, a 10 cm to 15 cm cover of compacted waste rock was placed on the pile. Outflow, precipitation and run-off data collected during natural and artificial rainfall events have been used to quantify the maximum infiltration rate, and the spatial pattern of discharge and cumulative volume of water that infiltrated into the waste rock under each surface condition. Infiltration data together with the outflow data provide a basis to address the residence time of water within waste rock and the dominant flow mechanisms for different surface conditions. With a free dump surface spatially distinct wetting fronts are observed at the base of the pile that vary in flow rate by an order of magnitude (measured at a 2 m by 2 m scale) and in time by up to a week. Following ripping and levelling, similar cumulative outflows were observed, but the magnitude and arrival time of wetting fronts changed across the pile. A decrease in outflow volume, a decrease in infiltration volume, a two-fold increase in the response time of wetting fronts and a more spatially uniform distribution was observed following placement of the compacted surface layer. Based on preliminary data, the internal structure appears to be the dominant factor controlling outflow variability.

Jan 1, 2003

Western Mining Corporation (WMC), managers of the Windarra Nickel Project, installed a raise-bored haulage shaft and underground crushing system at the Mt Windarra Nickel Mine in 1982. The system is the second of its type installed by WMC, the first being at the Otter Juan Mine in Kambalda in 1976/77. Both haulage systems became necessary as a result of the increasing production limitations, and escalating costs of a deep decline mine.The Windarra haulage system required a single 3 m diameter vertical raise drill hole, 470 m deep and equipped for skip haulage. Two five tonne skips, in balance, hoist crushed ore and mullock to the surface, at a design rate of 200 tonne/hr, effectively reducing truck haulage leads by up to 50 per cent. The system is now fully operational and will enable the mine to achieve its maximum production rate.The raise-bored shaft system has been shown to be cost effective and would be used again in circumstances where raise drilling is applicable.

Jan 1, 1984

The old Trekelano mining area is situated in the Cloncurry Gold and Mineral Field 14 km east-south-east of Duchess. It connected with the main Cloncurry-Dajarra railway line by a private line from Juenburra, a distance of 10 km. The distance by rail from Townsville is 561 km. The area was first mentioned circa 1902 - 1903 when a very short report said, that a Tony Allis had taken a parcel of copper ore out of a mine which, he called æThe InheritedÆ. After that report, nothing further was printed until about 1906, when traces of copper were noticed on a wagon track going to Kiama Well. The Trekelano deposit did not outcrop, with the cap covered by about two metres of soil. The deposit was named after an early pastoral holding. The early prospectors were however disappointed by TrekelanoÆs low copper grades, approximately five per cent Cu. This is understandable when, in those days, about 25 per cent was the cut-off grade for mines in the district. Meanwhile, The Hampden Mining and Smelting Company were constructing a smelter to treat their sulphide ores at Kuradala that was replacing their high grade oxides ore. By about 1910, the Hampden Mining and Smelting Company was experiencing smelting problems, and needed suitable oxidised copper ore to blend with the Kuradala pyritic ore. Someone must have remembered the Trekelano low-grade oxides, resulting in agreement to mine and cart the ore to Duchess, from where it was railed to Hampden, as Kuradala was known at that time.

Jan 1, 1998

By O C. Aitken

Mining project developers are committed to taking on all the challenges and obligations of financial risk management. It is interesting that our current models of project finance have not changed markedly in principle for some 700 years, yet the rules which prepare the way for effective project assessment and subsequent loan management still do not seem to be well understood by project or corporate developers. Probability and gravity fill the opposing trays of the golden balance of financial risk. Understanding the relationship between these opposing, but intimately related elements is critically important for successful risk management. It is important to move beyond the qualitative approach and use quantitative methodologies to measure the financial impact of the occurrence of each major risk. We live in a world where the only constant is change and thus it is not surprising that a bankerÆs life is still governed by assessing, measuring and pricing risk. Banks are attracted to funding well managed companies with strong cash flow projects. But we are more risk averse compared with the credit appetites of late last century. This attitudinal shift has resulted in tougher term sheets for the early 21st century, encompassing more conditions, warranties, undertakings and stronger cash sweep provisions. Banks require well balanced portfolios to achieve an acceptable spread of risk, thus there is a more restricted market for small company lending than that available to large multi-project corporate entities with less concentrated risk profiles. Because of this focus, junior company debt finance remains comparatively expensive and especially so for more challenging geographical and political environments.

Jan 1, 2004

By J N. Moncrieff

The resource estimation process for the underground Mount Isa Copper Mine has undergone significant change. Block models are now created using a commercial software package as opposed to the in-house software that was previously used. With mineralisation occurring over a strike length of more than 4 km, Mineral Resources for all categories totalled 190 Mt at 2.7 per cent Cu at 31 December 2002. Estimation is by ordinary kriging with two separate models generated to cover the X41 and Enterprise orebodies respectively. The underlying Upper Basement Contact and the silica-dolomite alteration envelope are both used as hard boundaries to constrain the modelling. From a validated block model, grade shells are generated at the appropriate cut-off grade for a given area. The grade shells are depleted for mined voids and subdivided into 30 metre strike length blocks. Application of a SMU criteria and crown and pillar constraints results in failed blocks being culled from the resource inventory. Mineral Resource blocks are further subdivided into resource categories (Measured, Indicated, Inferred) by the Competent Person on the basis of geological confidence, taking account of geological and grade continuity, drillhole spacing and structural complexity (JORC, 1999). A geostatistical æconfidenceÆ category is incorporated into the block model as an additional tool for the categorisation process. The shapes are assessed in concert with a mining engineer to determine whether a reasonable expectation of mining potential exists and if not they are removed from the resource. The final categorised blocks constitute the Mineral Resource inventory and form the basis for conversion to Ore Reserves. The resultant Mineral Resources and Ore Reserves are reported on an æinclusive ofÆ basis.

Jan 1, 2003

By J Ding, H J Peng, S B. Zhu, L Hou, J R. Zhang, S Y. Wu

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Numerous Fe-Cu-Au-rare earth element (REE) deposits have been identified within the Palaeoproterozoic Dongchuan Group of the Kangdian region of SW China. Geochronologic and geochemical data of the dolerite dykes and other volcanic rocks reveal extensional activity occurred about 1.7 Ga called ‘Kunyang Rifting’. The Kangdian region underwent variable degrees of extension, meaning that breakup in the central part of this region occurred earlier than in the north. Research on microphysiography, isotopic geochemistry and inclusions of the Yinachang typical Fe-Cu-Au-REE deposits suggest that the dominant mineralisation fluid is high-temperature, high-salinity magma fluid, containing alkalic components, volatile phase and Cu-Au. Metasomatism and mixing between this magmatic fluid and carbonaceous wall rock and meteoric water caused the precipitation of Fe, REEs and Cu-Au. A chalcopyrite Re-Os age from the Yinachang deposit obtained during this study is some 50–100 million years younger than the timing of emplacement of the deeply sourced Haizi and Dongchuan dolerites. The Yinachang deposit is a typical iron oxide-copper-gold (IOCG)-type deposit, and the presence of this and other deposits in the Kangdian region indicates that the region hosts an intraplate extension-related IOCG system within the western edge of the Yangtze Block, China.CITATION:Hou, L, Ding, J, Zhang, J R, Zhu, S B, Wu, S Y and Peng, H J, 2015. Proterozoic iron oxide-copper-gold mineralisation in the Kangdian Region, south-west Yangtze block, China – a case study on the Yinachang Fe-Cu-Au-rare earth element deposit , in Proceedings PACRIM 2015 Congress, pp 255–264 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

"Cash flow modelling during project evaluation is enhanced when probabilistic methods are applied to the inputs. One of the important inputs is the quarterly production profile. Typically, the steady-state production profile provided to project evaluation practitioners is deterministic, with each quarter the same as every other quarter. This is unrealistic as actual production profiles from existing mines exhibit a range or quarter-on-quarter variance. Monte Carlo stochastic simulation of the production profile can be used to provide a range of possible outcomes, but how are these ranges selected? This paper describes the use of quarterly production variance from a large database of mines worldwide as a benchmark to inform the appropriate selection of ranges. The coefficient of variation is used to rank the production from mines, with quartile analysis applied to indicate industry best, median and worst variation. Due diligence of existing mines and evaluation of future production performance can be quantitatively assessed using this approach. Examples of the effect on value are provided.CITATION:Stewart, C A, 2016. Production variance benchmarks and their use in project evaluation and due diligence, in Proceedings Project Evaluation 2016, pp 201–213 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By A M. Wala, H W. Wu

A research project incorporating a number of mine site exercises to reduce the effects of fire incidents and possible consequent health and safety hazards has been undertaken focused on the application of mine fire simulation software packages for contaminate tracing and fire modelling in coal and metalliferous mines. This paper examines aspects of introduction of inert gases to underground workings to aid recovery of a mine following a fire. Broad conclusions from work undertaken at individual Australian coal mines are discussed as examples. The effort is built around the introduction of the fire simulation computer program æVentgraphÆ to the Australian mining industry and the consequent modelling of fire scenarios in selected different mine layouts. Case studies have been developed to examine usage of inertisation units and particularly application of the GAG jet engine unit. One example has focused on selection of the best surface portal location for placement of the GAG for most efficient suppression of a fire. A second has examined a situation with significant seam gas being emitted on the face. This has shown that under certain face dip angles stopping the mine surface fan to reduce dilution of GAG exhaust gases will cause reversal of face air and consequent mine explosion as gas laden air is drawn across a fire. A third examines inertisation and dilution issues in mains headings. mains headings present a complex ventilation network with often numerous parallel headings, hundreds of cut-throughs and a variety of ventilation control devices. In such a complex system (with additional interference from a fire), maintaining control of the movement of inert gas is more difficult than elsewhere in the mine. Some illustrations of this issue are given.

Jan 1, 2005

By I Mason, G Turner, J Hargreaves

One of the key objectives in production from any mine is the minimisation of ore loss and dilution. This can only be achieved when the distribution of ore within the mine is known. The distribution of ore is usually evaluated from a combination of drill hole information and underground mapping data. Three-dimensional models of the ore distribution are then constructed by interpolating grades, contact locations and confirming these estimates through mapping. While the interpolation procedure can incorporate an understanding of the local geological conditions, it is an approximation and thus susceptible to some degree of ore loss or dilution. Naturally, such problems increase in areas of sparse geologic information or greater geologic complexity. Borehole radar offers an approach to decrease the interpolative aspects of modelling by providing a continuous image of some ore contacts. Borehole radar works by building a two-dimensional image of an ore contact from radio waves bounced off the contact from closely spaced positions along a borehole. This image can be imported into Datamine (or a similar design package) and incorporated into geological models of a given ore block. The results of a trial survey from the Mariners nickel mine at Kambalda are presented to illustrate the improved level of detail and accuracy that can be achieved through the incorporation of borehole radar into orebody delineation practice. Once implemented on a large-scale this technique has the potential to greatly increase the cost-effectiveness of long hole stoping at Kambalda, through increased ore recovery and reduced dilution.

Jan 1, 2000