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The Ranger Project Area covers 78.6sq km and is approximately six km east-west by 14km north-south (Fig. 1). The area is known to con- tain two uranium orebodies, Ranger No. 1 and No. 3, two uranium occurrences, Anomalies 4 and 5 and three significant radon anomalies, Ranger 18, 19 and 48. The Ranger No. 1 and No. 3 Orebodies con- tain approximately 120 000 tonnes of U308 in highly chloritised metasediments of the Lower Proterozoic Cahill Formation. The orebodies occur as suboutcrop and exhibit significant radiometric anomalies. These occur within approximately 400m vertically of the projected unconformity with the sandstone of the Middle Proterozoic Kombolgie Formation. Oxidised and reduced uranium minerals occur in quartz-rich schists containing variable muscovite, chlorite and sericite and in the chloritic matrix of chert breccia. Secondary uranium minerals namely saleeite, metatorbernite and gummite associated with earthy iron oxides occur from the surface to 50m depth in No. 1 Orebody and up to 80m depth in No. 3 Orebody. Below the oxidised zone, uranium occurs as pitchblende finely disseminated throughout sequences of quartz muscovite chlorite schist up to 150m thick and as open space fillings in zones of structural deformation. The uranium-bearing schists directly overlie up to 300m of dolomite and magnesite containing minor interbedded schist units and are themselves overlain by approximately 2 000m of more micaceous schists of the upper part of the Cahill Formation. Regional metamorphism has occurred to at least amphibolite facies and has been followed by retrograde metamorphism to a greenschist facies equivalent. The metasediments are intruded by granitic pegmatites and dolerites. Uranium is associated strongly with chlorite of which there are at least five textural varieties. Not all of the various generations of chlorite have associated uranium. Graphitic schist horizons occur which are often less than one metre thick and discontinuous. These are best developed at the base of the quartz chlorite schist sequence where uranium grades up to 1 000ppm U may extend for several hundred metres beyond the main ore zone. Uran- ium is not common in the carbonate sequences and only occurs in chlorite segregations in disrupted zones. The unoxidised ore contains sulphides, mostly pyrite, which are low in abundance (

Jan 1, 1984

By Loo C. E

Thirty two polyacrylamide flocculant samples were selected from the wide range offered to the Australian coal industry. An extensive test program was conducted to consider the properties of the flocculants, the substrates, the process conditions and the water chemistry encountered in coal preparation plants. The study indicated that flocculants with molecular weights of 12 to 14 million and degree of hydrolysis around 40% gave the best "average" performance over a wide range of process conditions. The pick-up and filtration of fine coal was demonstrated on a pilot scale to be a critical function of flocculant properties. This study also showed that the agitation intensity during flocculation was a critical parameter in determining the settling rate of the slurry and the clarity of the resulting supernatant. An electronic meter to measure agitation intensity was designed, constructed and tested to demonstrate how, for the first time, laboratory results can be implemented in operating plants.

Jan 1, 1989

In 1980 Pancontinental Mining Limited decided that while the Jabiluka uranium project was still a major focus of the company's efforts some diversification was necessary. At this time it was decided to include precious metals in Pancon's exploration and acquisition objectives. As a result the now Paddington Gold tenements were acquired, explored and developed. Today, it rates as the 6th largest gold mine in Australia and at an expanded throughput of 1.2 million tonnes per year of ore it will produce about 110,000 ozs of gold per year. Following extensive exploration activities by Pancon's Exploration Division the Operations Division continued with development drilling finally proving up a reserve of about 8.4 million tonnes at an average grade of 3.2 g/t. An in- house preliminary feasibility study was followed by a two phase feasibility study by Davy McKee. This resulted in a recommendation to the Pancon Board of Directors to develop Paddington with an annual throughput capacity of 875,000 tonnes. This paper describes the acquisition, exploration and development of the Paddington project. It goes on to

Jan 1, 1986

Lungfish and crayfish inhabit continental ecosystems similar to those of their ancient counterparts in the Permian (lungfish) and Triassic (crayfish) Periods, exhibiting similar burrowing behaviors to live, breed, and escape desiccation. Identification of their burrows in the geologic record when body fossils are absent has relied on the overall gross morphology of the burrows and the process of elimination. A method of burrow identification has been developed by evaluating burrow structures in an attempt to designate architectural and surficial burrow morphologies that uniquely reflect the distinctive burrowing mechanism of a particular organism. The information from this method defines the burrowing signatures of an organism, enabling the differentiation of their burrows even when fossil evidence is lacking.The lungfish constructed simple, vertical burrows with bulbous terminations. The burrow walls exhibit fine, horizontal to sub-horizontal striae and vertical to sub-vertical striae near the top of the bulbous terminus, reflecting a burrowing style similar to modern burrowing lungfish. The crayfish constructed simple, vertical burrows to complex burrows with multiple branching and chamber development. The burrow surface ornamentations exhibit horizontal to sub-horizontal ridges, vertical to sub-vertical groupings of scratches, mud- and lag-liners, knobby and hummocky textures, and body impressions, which reflect the burrowing mechanism of the crayfish.

Jan 1, 1990

Just as geophysics, in the form of 3D seismic and wireline logging, plays a key role in petroleum reservoir management, so too will geophysics play an important role in mining of coal, metals, and minerals in the 21 st century. The commercial and social imperatives driving greater use of geophysics are reduced costs, increased revenues, and enhanced safety. In short, superior utilisation of capital and management of risks. In relatively undeformed sedimentary environments it is possible to adapt petroleum-style 3D reflection seismic to image mines. This has been demonstrated most impressively in the Witwatersrand. Anglo-American, for example, completed a $1 million 3D seismic survey at Western Deeps in order to site a new $300 million shaft with confidence. Likewise, 3D seismic has gained rapid acceptance at Australian coal mines in recent years. Encouraged by these successes, metalliferous mining companies are supporting research in Canada and Australia, as well as South Africa, to adapt 3D seismic for more highly structured, metamorphic terranes. Because the mining industry is far more diverse than the petroleum industry in terms of commodities and geological environments, 3D seismic is not always cost-effective. A plethora of other geophysical techniques can be applied, many of which are employed in mineral exploration. Mine applications of geophysics differ from traditional exploration applications in two main ways: time scales and length scales are shorter, and boreholes are more plentiful. Borehole geophysical techniques therefore play a more significant role, both for logging and imaging. Logging systems detail the variations of in situ physical properties down the borehole at scales measured in centimetres, while geophysical imaging techniques can map features located tens or even hundreds of metres from the sensors. While geologists tend to think of boreholes in terms of chips and core, geophysicists perceive them first and foremost as access paths for instruments. Borehole logging has been employed at iron and coal mines for decades, mainly to accurately define ore boundaries in delineation holes. In base metal mines, Outokumpu implemented logging widely for orebody delineation in percussion holes in the 1980s. The benefit was a direct cost-saving, arising from substitution of core drilling with percussion drilling plus borehole logging. The practice has since spread to other companies. INCO, for example, defines nickel boundaries in blast holes at Sudbury using conductivity logs. The benefits are in the form of reduced dilution and enhanced ore recovery, flowing from a more accurate mine model. Density, natural gamma radiation, magnetic susceptibility, and conductivity are the principal metalliferous mine logging parameters because they can be recorded in both dry and water-filled holes. Sonic velocity is the premier geotechnical logging parameter, given its sensitivity to rock strength, stress, porosity, and degree of fracturing. Sonic is recorded routinely in exploration and geotechnical holes at coal mines. With the advent of slimline dipmeter, full waveform sonic, and optical and acoustic scanner tools, the role of borehole logging in geotechnical evaluations is expanding. Monitoring of strain and micro-seismic activity enhances safety during mine production. While qualitative interpretation of logs is adequate for stratigraphic identification or definition of boundaries, a wealth of quantitative information, eg density, can be derived from properly calibrated, repeatable geophysical logs. Moreover, geophysical logs can sometimes serve as surrogates for geochemical assays, and not only for magnetite and uranium. At OutokumpuÆs Kemi chromite mine, for example, gamma-gamma logging provides the basis for grade control. By reducing reliance on assaying, three benefits can be realised: reduced reliance on core drilling; lower core handling and assaying costs; and shorter turn-around times. Conventional downhole EM and borehole magnetics are used for near-mine exploration, and for ground sterilisation. Inco has enjoyed considerable success with borehole UTEM in the Sudbury Basin, for example, and Geopeko has applied three-component borehole magnetics successfully in the Tennant Creek area. Electrical techniques such as applied potential and magnetometric resistivity (MMR) are also finding application at mines. For higher resolution, borehole seismic, radio imaging, and radar have been invoked, with varying degrees of success, to delineate orebodies and map structures, or to geotechnically characterise the rock mass and identify hazards. Success mapping nickel sulphide shoots with borehole radar has been reported by WMC at Kambalda. There are no universal geophysical panaceas, and each mine imposes different geological, logistical, and economic constraints. Geophysics will not always be cost-effective. However, the greatest single impediment to expanded use of geophysics at mines has been the low level of awareness of geophysics on the part of most mine geologists, engineers, and managers and, equally, the limited understanding of mine geology and engineering exhibited by the majority of geophysicists. This myopia will be remembered as a 20th century affliction! Blue Sky areas for mine geophysics in the next ten years include integration of geophysical data acquisition with drilling, enhanced grade estimation and rock mass characterisation, and the incorporation of geophysical information into mine models using geostatistical techniques. All these advances will be predicated on an expansion of petrophysical knowledge.

Jan 1, 2000

A statistical investigation of folding at Mount Isa disclosed similar patterns in both the shales and the "silica dolomite" zones. Analysis of these patterns yields 3 groups of folds fully developed north plunging folds, fully developed south plunging folds, and flexuresrepresenting stages of development of folds. Interpretation of results indicates that a regional force from a southerly direction was responsible for the folding.The general pattern of shearing is allied to that of folding, with the exception of bedding-plane shearing. Many shears resulted from continued application of force on folds which ruptured after overthrusting. Other shears resulted from rupture of the more incompetent shale members, without associated folding. The shear pattern is consistent with the theory of a regional force from a southerly direction.INTRODUCTIONThe notes on folding and shearing presented in this paper are part of a current study of the structural geology of Mount Isa.FOLDING 1Measurement of FoldsInvestigation of folding underground involved the measurement of plunge, strike and dip of the axial plane, and the order of magnitude of each fold, together with its location and the rock type. The total number of folds measured was 701, of which 411 occurred in shale areas and 290 within the "silica dolomite" zones. All folds measured are located on main levels, from 7 level to 13 level inclusive. The sections of the mine involved are the Black Star, Black Rock and Racecourse. Detailed investigation of folds on the upper levels (4, 5 and 6) has not yet been done, but observations there suggest...

Jan 1, 1961

By Sneddon J

This Is not a highly technical paper, but rather an attempt to give a general outline of coal mining for the benefit of those present who may have little or no experience in the industry, and is intended to give some general knowledge which may help to a better understanding of the problems of the industry. A knowledge of the disposition of workable material is necessary to give a comparison with other mining practices. Coal Is usually found in comparatively fiat seams of varying thickness, whereas other minerals are generally found in highly inclined lodes of variable width. However, even in comparatively flat seams unaffected by faulting, grades can, and do, vary greatly over short distances.This variation causes many local problems in working the small area affected. Even very steep seams, and some are much steeper than 1 in 1, vary considerably not only in grade, but also in direction of grade and level course. This is probably caused by folding during alteration of the shape and form of the basins after deposition.These swellies are common to most coal seams and vary only in extent. This type of variation in grade and direction of grade, while common to most ore bodies, is a matter of great importance in coal mining when it is considered that roadways are driven in the seam itself and have to be graded and made suitable for haulage purposes.The area of ground involved in an individual coal mining operation is often very large; many times larger than most metal mining propositions, and often comprises many thousands of acres.When it is considered that the specific gravity of coal may be only one-fifth of that of some ores mined, and the coal seam may be five or six feet in thickness, the vastness of the area necessary for continuous mining operations over many years will be realised.To achieve comparable outputs, with about five times the bulk of material to handle, much more ground and working places must...

Jan 1, 1947

By Browne TJ

On 13 October 1993, a shallow earthquake registering 7.1 on the Richter Scale occurred near Tauta in the Finisterre Range of Papua New Guinea (PNG) killing 37 people. The aftershock series lasted three months and resulted in considerable landslide damage that destroyed villages, food gardens and airstrips, and blocked rivers causing catastrophic flooding. These effects have irrevocably altered the form of many of the valleys and rivers draining into the Markham and Ramu valleys.The earthquake occurred in a pilot study area for a landslide hazard mapping project being carried out by the PNG Geological Survey that commen-ced in April 1993. Comparisons made between areas identified as unstable during the study with those damaged by the earthquakes show good correlation.It is concluded that aerial photograph and Landsat TM imagery interpretation can be used with a high degree of confidence to identify potential landslide hazards in mount-ainous terrain. Landslide hazard maps are promoted as a tool for use in the route planning of roads and powerline corridors, as well as for identifying vulnerable communities.

Jan 1, 1994

By Toro HCH, Von Borries GH

A brief description of the semi-autogenous grinding (SAG;) facilities of Compania Minera Disputada de Las Condes is given. A data-logging and computer system was connected to the plant inter facing the existing analog control system in a supervisory s, control philosophy. The development of a control straiov,v t,) maintain maximum power of the SAG mill atsubjected to process restrictions is shownThe present control scheme is discussed inalgorithm was designed based on correlations onLween vartaoles. Associated with this, a direct level of control was developed be, on classical control algorithms, process inter-active tuning has been included. Also, an algorithm to prevent overloading of the is discussed. Control scheme tests are presented in comparison t manual operator control under the same conditions. It is shown t the control strategy gives a more stable operation and a higher plant throughput.

Jan 1, 1985

Driefontein Gold Mine together with Kloof Gold Mine and Beatrix Gold Mine forms part of Gold Fields South Africa. Driefontein Gold Mine is situated near the town of Carletonville, 50 km south of Johannesburg, in the Gauteng Province. The 4 Shaft East complex comprises of the 4 Main Shaft and the 4 Subvertical Shaft. The main shaft is 9150 m in diameter and was sunk in 1984 to a depth of 2000.5 m. The 4 Subvertical Shaft is 7320 m in diameter and was sunk during 1985 to a depth of 3006 m. Full production was, however, only reached during 1988. Intensive mining is currently being done between levels 28 to 42. In 2002 a decision was made to start mining the shaft pillar, situated between 32 and 33 level in the subvertical shaft. Intensive studies showed that with selective mining scheduling the total mineÆs life could be lengthened by nine years if accessed timeously. The higher grades present in the shaft pillar can be mixed with lower grades from the same reef band presently mined 1500 to 2000 m away from the subshaft pillar area. The shaft pillar comprises 50 per cent of the remaining ore resources available. However, no provisions were made in the initial phases of the shaft development to extract the shaft pillar. Grades between 4300 cmgt to 2500 cmgt relating to 23 and 14 g/t are present in the shaft pillar and an estimated 50 tonnes of gold can be produced from this pillar in the period from 2007 to 2015. The pillar extraction is the key to DriefonteinÆs long-term gold profile. Every geological feature possible is represented in this to-be-mined pillar area. The pillar around the shaft is a complex structure featuring hard and soft lava, sedimentary structures/plane parting that moves against each other, quartzite capping, etc. Replacement of services and secondary support systems were designed, modelled and put in place. The original steelwork was not designed to cope with the various stresses and movements, which are expected once the extraction process is started. Existing shaft steelwork was used as far as practically possible. The principal behind the design was that the steelwork would be totally disconnected from the shaft lining over its total length of 132 m in the area of the reef intersection. This will allow the steelwork to move independently from the geological structures surrounding it, allowing a certain degree of distortion of the shaft lining, moderate twist and tilt to take place without interfering with hoisting operations.

Jan 1, 2005

By A G. Pavlides, B L. Weekes

The Sepon Copper Project is located in the Savannakhet Province of Laos PDR and is operated by Lane Xang Minerals Ltd (LXML). An Ausenco - Bateman Engineering joint venture, the Khanong Development Group (KDG) managed engineering, procurement and construction of the project. The plant was fully commissioned in March 2005, two weeks ahead of schedule. The plant is designed to produce 60 000 tpa of cathode copper. The process flow sheet includes a pressure oxidation (POX) circuit that leaches pyrite flotation concentrate to generate ferric ions and sulfuric acid for use in atmospheric leaching of a predominantly chalcocite ore. The process is unique in that the chemistry in the autoclave is forced to produce a basic ferric sulfate precipitate for downstream recovery of ferric iron. This paper describes the design, construction and commissioning of the pressure oxidation circuit. The challenges imposed on construction and commissioning due to the remote location of the site, landlocked status and underdeveloped infrastructure in Laos are highlighted.

Jan 1, 2005

WaihiÆs Cornish Pumphouse is located on the edge of town in a dynamic and changeable area where history affects the future. As in any successful project, ingenuity and team work have been significant factors in the planning and implementation of the buildingÆs relocation.   Work around the Pumphouse site commenced circa 1900 with preparation to sink the No 5 shaft. Construction of the pumphouse and the steam driven C pump was completed by 1904 with hints of what was to come evident in 1905 as the No5 Shaft collar had sunk 350mm in four years. By 1907 surface cracking developed over the Milking Cow cave area and in 1913 200 mm was cut off the main pumping rod as the ground was sinking at a rate of 25 mm per year.   In 1913 ground around No 6 shaft had subsided 600 mm.It was also the end of an era as steam gave way to hydroelectricity and electric pumps replaced the C Pump. C Pump was maintained as a backup from 1913 to 1929 and then finally scrapped. 25 years of underground caving operations removed approximately 400 000 cubic metres of ore leaving a 7 ha collapse crater that eventually became known as the mine lake.   On the edge of town a tension zone over the Royal Lode began to develop 50 m diameter chimney collapses as large scale blocks relaxed into unfilled stopes in the old Martha underground mine. After the 1999 collapse part of the main street was closed and after the 2001 collapse Hazard Zones were declared, more streets closed and areas evacuated and retired from residential use.   By 1984 the Pumphouse has approximately one degree of tilt and in 2002 tilt on the Pumphouse accelerated briefly and then settled down. Tilt accelerated again late in 2004 and a scoping study was initiated to define protection options for the pumphouse. The Martha Mining Licence requires Newmont to 'Take whatever precautions are necessary to protect the old Cornish Pumphouse adjacent to No5 shaft' and viable solutions needed to found.   Any work on the Pumphouse comes standard with a wide range of stakeholders, governing agencies and legal framework to consider. Land Information New Zealand (LINZ) is owner and administrator of the pumphouse.

Jan 1, 2006

In November, 1967, a four strand curved mould continuous casting machine coupled with a 50 ton basic oxygen furnace began producing billets for the rod mill and new merchant mill at the Newcastle Steelworks. To date over 500,000 tons of carbon and alloy steels have been cast at the rate of 20,000 tons per month, the major part for the wire industry. Many alterations have been made to the plant to simplify the process, improve quality and increase production. Casting parameters have been developed for each different type of steel. The quality of the final product has been influenced most by casting temperature, secondary cooling and casting speed. All these factors have been controlled and good results are reproduced. More exacting requirements of liquid steel quality have brought about the use of higher lime/silica ratio slags during steelmaking to control phosphorus revers- ions and standard ladle additions of manganese suicide and ferro aluminium for more effective deoxidation.

Jan 1, 1972

By Hall S, Upton D

WMC Resources Ltd nickel operations have expanded significantly over the last three years. Production capacity has increased at mine/concentrate, smelting and refinery processes to such an extent that WMC now ranks within the top three or four producers of nickel metal in all forms. The stainless steel industry remains the dominant user of nickel. WMC's forecast is for stainless steel production to grow at 2.8 per cent per annum off of the 1995 peak, with much slower growth in the short-term as the stainless steel inventory overhang unwinds, followed by a return to higher trend growth rates. WMC's forecast for the long-term growth in demand for primary nickel is three per cent per annum off the 1995 peak; again, slower growth in the short-term before a return to higher long-term trend rates. This projection is towards the optimistic end of the range of industry experts. It equates to a requirement for new primary nickel of 25 000 to 30 000 tonnes of annual capacity each year.

Jan 1, 1996

This paper is directed at the problems flowing from Australia's capital gains tax (CGT) on the disposal of exploration and mining tenements both in Australia and overseas. It will seek to identify the issues and give some idea of the dollar consequences of decisions lacking forethought. The paper should not only be seen in the context of Australian tenements. CGT applies to the disposal of any assets by an Australian resident anywhere in the world. Offshore incorporated companies are not necessarily free from CGT risk where it can be shown that control management and control of the relevant company is in Australia. Also the disposal by non residents of Australian tenements are potentially caught by CGT. Some will ask what has taxation got to do with a valuer who merely determines the value of assets. These days no determination can be blind to the consequences. Whether the consequences can encourage a movement in value is another thing dependent upon the circumstances; but? A role of an experienced taxation consultant is to point out parameters within which associated professionals can work. The parameters will vary from case to case, but these when clearly indicated may be of help to persons such as valuers. When one comes down to it real estate salesmen are never wrong. They have a feel for the market and almost through self fulfilling prophesies achieve sales at their guestimates. Whether they could have achieved higher considerations become virtually academic in the process. Of course I am not suggesting that tenement valuers can be compared to real estate salesmen, or am I? What is the value of a tenement? Is it the DCF/NPV type of generated value based on a large number of variable factors (ie what one may call the fundamental value)? Or is it what another may pay to purchase that tenement if it were on the market at an instant point in time? How big is the market, the quality of the bidders, the size of their purses, the needs of the buyer for comfortable fit, the premiums for foreigners, the standard of the marketing, the industry intelligence level of the bidders, the obligation to farm/sell down? The list goes on endlessly. One question must be.asked-"Is a range of values acceptable for tax purposes". ie Would any tax consultant ever provide a valuation to the Australian Taxation Office that indicates three or more possible values ie

Jan 1, 1987

Any Australian who knows of the poverty of the early settlers in the first few years following the arrival of Captain Arthur Phillip with his "first fleet" at Botany Bay must feel proud of the progress that has been made in the 174 years that have elapsed since that momentous occasionGFor all its attractive appearance as reported by Captain Cook and Sir Joseph Banks, the shores of Botany Bay and of Port Jackson proved most ,inhospitable, and the accessible country surrounding them anything but suitable for sustaining the life of the small settlement. It is well known that during the first 15 or 20 years the hardy colonists and un-tfortunate convicts were close to starvation on several occasions and were only saved by the arrival of supply ships, which were dependent on the vagaries of wind and current, and the hazards of the uncharted seas they had to -navigate-.When Australia was little more than a miserable penal settlement, Great Britain was one of the great-powers of the world, and the U,.S.A. was an independent nation with a growing degree of prosperity that even then gave promise of its mighty awakening to become, as it has, a e.olossus of industry and commerce,-and the. leader in living standards of the world to-day.Australia, from such a shaky, and comparatively recent start, has risen to a position in which its living standards rank very high in comparison with those of most of the nations of Europe and America. Exact com-parisons are hard to fix because of the wide variety of factors involved .but the Institute of Pab?Lic Affairs .(Victoria) places Australia fifthin the world, excelled only by the U.S.A., Canada, Sweden and Switzerland. The next best after Australia are the United Kingdom, West Germany and France.How we achieved such a high standard of living is a vast subject for study but some of the economic aspects of our climb from abject poverty to a position of near affluence can readily be identified.

Jan 1, 1962

By D Corley, J Moore, M Grant, A, W R

Resource estimates are the corner stone of technical and investment decision-making. Prior to mining, resource estimation uncertainty has the greatest potential to lead to poor investment decisions, despite a significant component of resource estimation uncertainty being unknowable at this critical stage in the mining cycle. This presents a conundrum to the resource geologist in terms of risk evaluation and resource classification. Ahead of mining, there is normally considerable focus on drill hole spacing analysis to determine the ‘optimal’ drill hole spacing, taking grade and geological continuity into account; cost-benefit analyses balance improved resource definition against cost; the law of diminishing returns and the exponential cost increases acting together as spacing is reduced. Typically, a lower limit to the drill hole spacing is identified. After completing the resource drilling to an agreed spacing, resource estimation is then undertaken. At this point it is common to attempt to bracket the resource estimation uncertainty. In many cases conditional simulation is used, based on a modelled, but largely assumed, variogram model. It is also assumed that the histogram of the available drill hole sample data is representative of the in-ground mineralisation. The purpose of this paper is not to diminish the importance of drill hole spacing and simulation studies, but rather to illuminate an important aspect of estimation uncertainty that, although previously recognised, is typically overlooked – the question of how representative the available data set is in characterising the true (but unknown) distribution of mineralisation. To do this, we lift the lid on one of OceanaGold’s former operations, the mined-out Globe Progress Mine, by resurrecting a high quality, close-spaced, reverse circulation (RC) grade control data set. The Globe Progress Mine is within the West Coast Region of New Zealand, it was closed and transitioned to rehabilitation in 2016 and is now known as the Reefton Restoration Project. The exhaustive Globe Progress grade control data was used to repeatedly ‘redrill’ the deposit by extracting 35 m × 35 m spaced subsets from the original 5 m × 5 m spaced grade control data. Utilising closely spaced grade control data removed the need for assumptions regarding short range continuity, which are necessary with forward-looking analyses that are based upon broader spaced resource drilling. The extraction process used a nearest neighbourhood algorithm, repeatedly moving the origin in 5 mE, or 5 mN increments. Individual resource estimates were then completed for each of the extracted drill hole data sets (49 in total) as well as a grade control estimate based upon the exhaustive data set. Whilst the data unpinning each of the 49 estimates changed, the geological assumptions, variography, and modelling parameters remained constant. This approach was taken to isolate the impact of changing the input data. The 49 estimates were then compared against each other and the grade control estimate. The mean of all 49 sensitivity estimates was close to that of the grade control estimate in terms of contained gold, tonnes and grade. Whilst it is acknowledged that the grade control estimate itself is subject to some degree of estimation uncertainty, the close match between the average of the 49 estimates and the grade control estimate suggests that the resource estimation methodology is reasonable and appropriate. Whilst this comparison is important, the focus of this study is on the component of estimation uncertainty related to the underlying data, and this is reflected in the spread across the estimates. The spread across the 49 global estimates (highest to lowest) for this particular Mineral Resource Estimation Conference 2023 | Perth, Australia | 24–25 May 2023 142 case study was found to be significant (approximately 20 per cent in grade and metal) and that is attributable solely to the underlying data. This exercise quantifies a component of the estimation uncertainty that is inherent to all drill hole data and is distinct from the uncertainties associated with modelling methodology choices, sample and subsample quality and drill hole spacing-related interpolation uncertainty. Importantly, this uncertainty is unknowable prior to mining; we can only directly compare the resource drill hole data against grade control data after mining has taken place. For the case study, approximately 65 per cent of the estimates fell within 5 per cent of the grade control estimate for contained-gold, suggesting that for many projects the histogram of drill hole data is unlikely to differ noticeably from that of the in-ground resource. However, about 15 per cent of the estimates in this study differed by more than 7.5 per cent, suggesting that a not-insignificant proportion of estimates will be materially compromised. Whether or not the available drill hole data is representative comes down to the ‘luck of the draw’ and cannot be known at the time of resource estimation. Given the challenge of attempting to evaluate forward-looking estimation uncertainty, a component of which that can only be quantified retrospectively, what should we do as resource geologists? What are the implications for risk evaluation, resource classification and reconciliation? Furthermore, without rigorous post-mining data checks, resource geologists may conflate suboptimal modelling with the shortcomings of the underlying data. An example of this problem is discussed in the following section.

May 24, 2023

By T E. Hayward, D H. English, S J. Smith

Gold mineralisation at Bendigo is exclusively associated with quartz reefs, commonly found within or near anticlinal fold hinges. The gold is typically coarse grained (0.5 mm to 5 mm), free milling and displays a complex, nuggetty distribution within the veins. This ore is highly amenable to gravity recovery processes. As the Bendigo operation is not permitted to treat whole ore by a cyanide leach/CIL circuit, the flow sheet is more complex than conventional gold recovery circuits. Primary gold recovery is from a gravity circuit closing the grinding circuit to a bulk gravity concentrate and from a flotation circuit treating cyclone overflow to a bulk float concentrate. The plant capacity is relatively low by current gold industry standards at 600 000 tpa. Re-establishing gold production at Bendigo has presented several challenging, and sometimes competing, issues in process design and operation. The mine, process plant, associated services and infrastructure are at Kangaroo Flat, a low density, semi-rural zone in the southern urbanisation of the Bendigo metropolitan area. One of the main processing challenges during the design was the competing comminution requirement to avoid over-grinding, which would flatten or smear the characteristic nugget gold and hinder effective gravity gold recovery, whilst also providing sufficiently well liberated particles that would respond well to flotation. Important, non-metallurgical challenges were to minimise impacts on the local community from noise, dust, air emissions, visual impact, water egress and off-site traffic.

Jan 1, 2007

By J M. Shekiro

In the chloride process to manufacture TiO2 pigment, feedstocks containing higher TiO2 contents (high-grade ores or HGOs) are favoured in order to minimise production of undesirable by-products. Most of today’s HGOs are produced through the smelting or reduction and leaching of ilmenite, processes which consume significant energy and/or produce large volumes of non-titanium materials that may have to be landfilled. In order to improve the economic and environmental sustainability of its TiO2 business, the DuPont Company, working with Kobe Steel Ltd, has developed an innovative process called TiRON for making HGO. Using a rotary hearth furnace, the process reduces ilmenite to a high TiO2 slag and metallic iron granules. The TiO2 slag is suitable for TiO2 pigment manufacture, and the iron is suitable for steel making. TiRON can process sand or rock ilmenite of varying compositions and particle sizes. Fossil fuel instead of electricity supplies the energy for the reduction. Dusts and off-spec materials are recycled. These process attributes, together with capital requirements estimated to be significantly lower, give TiRON substantial economic, environmental, and process flexibility advantages over conventional ilmenite upgrading processes. TiRON has been demonstrated at the semi-works scale, and preparations are being made to bring it to the pilot scale.

Oct 5, 2011

By D Prior

The Australian mining industry is a significant contributor to the nation’s greenhouse gas (GHG) emissions, and like any industry, it must make efforts to reduce these. Medium- and long-term strategies will include the replacement of diesel engines with alternative energy sources, but what can be done in the short-term to reduce diesel consumption and hence CO2 emissions? Haul trucks are identified as the major contributors of CO2 emissions in the mining fleet and this paper focuses on firstly identifying what drives haul truck emissions and secondly, discussing what is the role of the Fleet Management System (FMS) in reducing these. A key enabler of this is having a robust fuel consumption model within the FMS, and I describe how this may be done. Besides novel approaches to incorporating fuel consumption (CO2) management into truck assignment algorithms, this paper also describes how the FMS can be used to implement and manage procedures and policies to reduce haul truck emissions.

Jun 22, 2022