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By J B. Collier, R M. Fraser, O Dahl, I M. Platten

Grade control is a process of maximising value and reducing risk, through the delivery of quality tonnes to the mill via the accurate definition of ore and waste. It essentially comprises data collection, integration and interpretation; local resource estimation; stope design; supervision of mining and stockpile management. The foundation of all grade control programs should be that of geological understanding led by high-quality mapping and sampling to drive appropriate estimation strategies and mining. Gold veins show various complex features relating to erratic grade distribution (nugget effect), variable geometry and internal architecture. These include variations in dip, strike and width, late-stage faulting/shearing effects and geometallurgy. Such variations generally require close geological understanding to ensure optimum grade, minimal dilution and maximum mining recovery. A well designed grade control program will prove to management and stakeholders that by applying geological knowledge, the mining process can be more efficient and cost effective. This paper reviews the issues of grade control in underground gold mines and focuses on integrated mapping and sampling through three case studies.

Jan 1, 2009

The long-term outlook Tor Australla's traditional mining products is for flat demand and continuing low prices. This has come about because of three far-reaching changes since earlier boom days: 1. Continuing declines in intensity of usage of basic mine products; 2. The failure of newer western and third world developing countries to realise growth expectations; and 3. Continued production pressure from third world countries (and first-world primary producers) in an effort to earn foreign exchange and rectify trade balances. These trends have led to a general situation of excess supply and weak demand. In this environment, the prerequisites for survival in the mining sector are first-class mines, modern and efficient production methods, low unit costs, aggressive marketing, and products with reasonable operating margins. Many of Australia's mines meet these prerequisites. Following the A$ depreciation and widespread unit cost reductions, most of these mines will be moderately profitable at current depressed commodity prices. They are well placed to benefit from price rises if these eventuate. A new generation of mines is concentrating on a more profitable product range (gold, diamonds, uranium, mineral sands). Australia's balance of trade remains firmly dependent on the primary mining and agricultural industries (Fig. 1). Despite optimistic talk of high-tech developments, tourism and a resurgence of manufacturing, these will remain a small component of Australia's export structure.

Jan 1, 1987

By Q Zhou, J Pan, D Q. Zhu, C C. Yang

Oxidised pellets have become an indispensable high-quality charge for blast furnaces (BF) due to their uniform particle size, high iron grade, high mechanical strength, good metallurgical performance, as well as relatively low energy consumption and gaseous pollutant emissions in pellet production. Nevertheless, due to the rapid development of the global steel industry, highquality pellet feeds are becoming more and more scarce. In order to broaden the source of pellet feeds and reduce the production cost of pellets, more and more steel mills are going to use coarse iron ore fines with relatively low iron grade and low impurities for preparation of desirable pellet feeds through a typical wet grinding-settling-filtering process. In this work, the grinding, settling and filtering behaviour of Brazilian and Australian iron ore fines are studied and compared, aiming at finding out the internal relationship between the mineralogical characteristics of different iron ore types and their grinding-settling-filtering performance. The results show that the grindability is heavily dependent on the hardness of iron ores, which is governed by the mineralogical characteristics of the raw materials. Usually the higher the hardness, the more grinding energy is required. Except for Brazilian specularite, Australian hematite-goethite type iron ore fines and Brazilian hematite ore fines exhibit good grindability with a Bond Work Index of about 10–15 kW•h/t. In addition, the settling and filtering performance of ground iron ores are largely affected by the density, mineralogical characteristics of iron ore fines (eg, quantity of clay minerals and goethite and porosity of ore particles), grinding fineness, etc. Generally, iron ore fines with higher density, lower quantity of soft minerals (clay and goethite) and larger particle size give superior settling and filtering performance. For iron ore fines with inferior grinding, settling and filtering performance, applying more energy-efficient grinding techniques, blending with ore types with good settling and filtering performance can reduce grinding energy consumption and improve settling and filtration rates to maximise the productivity of equipment and lower the operational cost

Sep 18, 2023

Process variables in flotation circuits are outlined with a view to producing mathematical models of circuits. The nature of the kinetics of flotation are discussed and the effect of process variables on the kinetics considered. An approach for a possible model is briefly outlined.

Jan 1, 1971

By Baafi EY, Sun Y, Tague I

Field trials at three New South Wales and one Queensland coal mines were carried out to gather data on oxygen "run out" times of Self-Contained Self Rescuers (SCSRs), time taken to escape from the mine, distances travelled and the average heart rate of subjects wearing SCSRs. The study has led to a method of predicting the duration of oxygen supply from a SCSR as a function of the wearer's body weight, physical fitness and the prevailing environmental conditions. Escapeway design, planning for emergencies, familiarity with SCSRs and experiential escape training are critical to control panic and maximise the likelihood of survival of a person attempting to escape in an emergency involving fire or explosion.

Jan 1, 1998

This paper summarises the influence of slurry rheology on the grinding throughput of batch laboratory and continuous plant-scale mills operating in open and closed circuit configurations. The results of controlled changes in percent solids, particle size, slurry temperature, and viscosity control chemicals are demonstrated. An underlying rheological explanation of the above factors is offered which involves tying the specific rates of breakage that are occurring in the mill with the specific rheological character that the slurry is exhibiting at any given set of operating conditions. Some industrial scale operating guidelines are presented which have proven useful in increasing the net pro- duction capability of grinding circuits.

Jan 1, 1978

The coal resources of the Singleton- Muswellbrook area of New South Wales are of major importance to Australia, and are likely to play a significant role in meeting the expanding demands for energy in many countries of the world. Coal resources of 45 thousand million tonnes of which 15 thousand million tonnes lie at a depth of less than 200m have been estimated. The history of coal mining in the area commenced in the mid 1800's and has been one of fluctuations in production but of rapid expansion in more recent years. It is destined to become the largest coal producing area in New South Wales. Coal is being won from the area by strip mining, open pit mining and by underground means. The techniques involved are described. The area is well endowed with infra- structure such as modern towns, railways, road- ways and access to port facilities. Production of both coking coal and steaming coal is expected to rise significantly within the next 25 years. A large proportion of the State's anticipated increased production to between 117 and 177 million tonnes by the year 2000 is likely to come from this area.

Jan 1, 1979

The Hishikari gold deposit, discovered by the Metal Mining Agency of Japan, has become a giant class epithermal gold deposit with the highest grade of gold yet recorded in the world through detailed exploration and development by the Sumitomo Metal Mining Co., Ltd. The exploration strategy involved a regional approach combining geological and gravity surveys over a 900 km2 area which had historically produced over 120 t of gold. These surveys were carried out to grasp the common geologic features of epithermal gold deposits in the survey area. A genetic model for epithermal gold deposits in the area under regional survey was also considered based on detailed research of the Kushikino epithermal gold deposit which was in operation at that time. This model was applied to the targeted areas, and important relationships between mineralization, host lithology, intensive propylitic alteration and gravity highs became apparent. The Hishikari block was selected in this way and bonanza gold was discovered during drilling. Since the development of the Hishikari mine, information useful for further exploration for the same type of deposit has been accumulated.

Jan 1, 1995

By Bishop D. J

The Imperial Smelting Process for the simultaneous production of zinc and lead is probably regarded by the ecologist as a necessary evil with the benefits of its products marginally outweighing the adverse effects of its operation. The purpose of the paper is to examine the environmental impact of the process and to provide information which will demonstrate that the process has considerable indirect environmental benefits and that success is being achieved in reducing direct pollution of the environment by the process. About 12 per cent of the world's zinc and seven per cent of its lead is produced by the process. This proportion will increase with the construction of a new smelter in China. After a brief description of the process the paper considers one of its principal advantages, its ability to treat bulk concentrates. The production of these at the mine can have a number of environmental benefits. Less comminution may be required to separate the metals from the gangue than is needed to separate them from each other; recoveries can be improved in flotation resulting in cleaner tailings dams, less power demand and reduced consumption of potentially hazardous reagents. Simplification of mining and above ground ore handling may also give significant benefits . The process is a considerable consumer of secondary materials such as galvanisers' ashes, copper smelter dusts and materials containing zinc and lead derived from steel plant dusts. The majority of these materials are fed to the blast furnace after hot briquetting. The consumption of secondary materials is a considerable environmental benefit since otherwise they would require to be dumped in secure land-fill sites. The operation of the process itself continues to be subjected to increasingly stringent environmental standards of which examples are provided. Details are provided of lead emissions at Avonmouth showing considerable success in reducing these while increasing production. The slag from the process continues to find many useful applications.

Jan 1, 1993

As has been the case since the early Phoenician traders, the minerals used by modern man come from deposits scattered around the globe. The price received is more and more being set by worldwide supply and demand. Thus the price component in the profit equation:Profits = Material sold (units)x(Price/unit û Cost/unit) is largely determined by others. The recent price history for two of the major metals, copper and iron, are given in Figures 1 and 2, respectively. As can be seen there has been a steady decline in the prices (when expressed in constant dollars) over the 20 years which have lapsed since the first of the International Conferences on Mass Mining, æDesign and Operation of Caving and Sublevel Stoping MinesÆ was held. If one would look back over the entire 20th century this would also be the trend. Cost containment/reduction through efficient, safe and environmentally responsive mining practices is serious business today and will be even more important in the future with increasing mining depths and more stringent regulations. A failure to keep up is expressed very simply as: Profit This, needless to say, is unfavourable for all concerned (the employees, the company, and the country or nation). The mining companies have had to look at ways of reducing the expense part of the profit equation while maintaining safe, environmentally conscious operations. Table 1 summarises the rules for working in todayÆs economy.

Jan 1, 2000

The reduction in the number and duration of machinery and equipment failures is an important source of economical efficiency enhancement in the Polish coal mining industry.Non-dismantling methods have been thus developed to evaluate the technical state of machines. Among these viroacoustical methods are the most effectively employed. Two-directional organisation of the testing can be chosen, such as periodical and continuous inspection. The monitoring methods for ball bearing, rope tension uniformity, longwall shearers, main fans and shafts installations etc. Instrumentation for monitoring measurements are either of intrinsically - safe or explosion - proof construction, which enables using them in a gas-hazard atmosphere. The development of these procedures has led to the trials to insert the diagnostic methods into the organisational scheme of a coal mine.

Jan 1, 1991

The treatment of mixed lead carbonate and lead sulphide concentrates at Mount Isa presents a problem which is unique ,in the lead smelting world; a problem whose solution is far from simple, and is not yet complete. Two years of study under plant conditions have definitely proved, however, that a most satisfactory sinter can be made in a single-pass roast.The object of this paper is to present a brief record of the development of the single-pass roast and a resume of current practice in the smelting plant. The sintering operation is discussed in greater detail, as it is upon this phase of the work that every item in the smelter operating programme depends.The smelter, to-day, presents a very much simplified layout, equipped for economical, straightforward operation, requiring, however, very careful and constant supervision, due to the extreme delicacy of the sintering operation and to the rapid and wide variati9n in the nature of the concentrates which are to be handled.

Jan 1, 1933

By Mikula PA

This paper presents the results of in-situ and laboratory investigations into a mining method which utilises conventional continuous mining techniques to carry out two passes in thick coal seams, resulting in the development of stable pillars with relatively small width dimensions and heights up to 6 m. Geotechnical investigations included structural mapping, brightness logging and standard laboratory testing. Virgin stress was measured using overcoring techniques. Two approaches to pillar design were used in the study. These were; pillar design based on empirical formulae and laboratory testing, and pillar disign using calibrated mathematical models. A trial panel was developed at 300 m depth to study pillar deformation and stress changes due to mining. The extent of rib deformation was studied using borescopes and extensometers. In-situ geotechnical measurements were used to calibrate displacement discontinuity and finite element mathematical models of the coal seam. These models were then used to predict the behaviour of a small panel of pillars which were to be developed to 6 m height. The mining method was shown to be feasible provided adequate rib support was installed. The benefit of rib support was found to be two-fold, in that it increased confinement of the pillar in zones of low horizontal stress, while reducing horizontal stress relaxation in zones of high horizontal virgin stress. The possiblity of roof control by designing the small pillars to yield on retreat is discussed.

Jan 1, 1986

By Hunter W. H, Wilson I. P, Craig R. W

In September 1988 the Imperial Smelting zinc - lead blast furnace at Avonmouth England, was uprated from its then 52 week annual rated capacity of 90 000 tonnes/year of furnace zinc to 110 000 tonnes. In order to provide sufficient extra feed the sinter plant was likewise uprated in April 1989 by increasing the blowing rate of the sinter/acid plants from 100 000 to 120 000 Nm3/h, effectively a 20 per cent increase. In the 12 months after the uprate zinc production was only 85 000 tonnes. Two years after the uprate zinc production had increased to 100 000 tonnes, but it was not until January 1992 that a rolling 12-month zinc production of 110 000 tonnes was consistently achieved. This paper describes the problems encountered with the uprate and how they have been or are being overcome. It deals chronologically with events starting with the restart of the ISF at the end of 1988 and covers the following issues and their resolution: 1. Initial shortages of sinter due to an offset in uprate timing. 2. Greater difficulties in operating the larger furnace particularly on start-up, the greater tendency for iron production and serious slagging problems. 3. Coincidental timing of deleterious trends in slag chemistry. 4. Refractory problems in the furnace shaft and condenser. 5. Shortages of sinter due to commissioning problems with the wet gas and sinter tip end fans, and difficulties in obtaining sufficient sinter hardness. 6. Unrealised full benefits of the sinter-acid uprate due to a late change in design to dispense with sinter gas recirculation, but offset by successful use of oxygen. In a planned maintenance stop in September 1992 further improvements to the furnace design were carried out to resolve the refractory problems, and with improvements to the sinter plant the furnace zinc output capacity is planned to rise to a rate of 120 000 tonnes/year within two years.

Jan 1, 1993

By R Wolff

One critical factor in open pit mining projects is the estimation of the recoverable reserves. The reason for this is that at the valuation stage there is a lack of information about future metal prices and production costs. Consequently, the estimation of the recoverable reserves needs to be done based on a fixed break-even cut-off grade (BECG), in which fixed expected metal prices and production costs are assumed throughout the operating life of the mine (OLM). In this paper, an alternative technique for estimating the recoverable reserves of an open pit mining project is presented and explained in detail. The main characteristic of this technique is that it estimates the recoverable reserves of the project using mining costs as reference: this is done due to the fact that mining costs are easier to model than metal prices. Another important characteristic of this technique is that it uses the uncertainty of the geology of the orebody, given by simulations of the deposit, to make final strategic decisions, such as the selection of the operating life of the mine and the optimal production rate, which minimise the risk of not achieving future production targets while maximising the upside potential of future rewards. As it will be shown, the final outcome of the proposed technique is the generation of a robust open pit design, that include cutbacks and ultimate pit limits, called the marginal open pit mine design (MOPMD). One characteristic of the MOPMD is that, at each production period, it will be characterised by their respective geological uncertainty, given as probability distributions of ore, waste and metal quantities, and by marginal economical project indicators, such as cut-off grades and metal prices, among others. The details follow in the paper.

Jan 1, 2006

By P Hatherly, H Gurgenci

With the depletion of the mineral reserves that can be mined by surface mining, demand for highly productive and safe underground mines will increase. Underground drill and blast techniques continue to be refined but true æmass productionÆ is difficult to achieve. As is evidenced by the longwall mining of coal, alternative mining methods based on mechanised mining can meet the expectations but the issues of how to effectively cut strong rocks, how to define the orebody and how the mechanised miners can be automated and maintained all need to be addressed. CMTE is working in all of these areas. We believe that the oscillating disc cutter may provide the long sought-after breakthrough in mechanised rock cutting. Disc cutters are one of the most robust designs of cutting tool and the cutters attack the rock in a manner which effects direct tensile breakage. The internal cutter drive and the inertial damping mean that the already low cutter forces are not all transmitted back to the machine, making it possible to design lightweight, flexible mining systems. For orebody delineation drill monitoring, drillhole logging and geophysical imaging are key procedures being developed at CMTE. To automate mining machines, work is progressing well in the development of systems for autonomous vehicle navigation and mining robotics. A strategic contribution to maintenance issues is being made through the development of procedures for automatic analysis of used oils, monitoring the strength of mechanical structures, and operating point optimisation.

Jan 1, 1998

Dr Wark said: I have not come to Broken Hill to tell you how to conduct flotation operations; indeed, during my short stay here I have already learned much concerning the process, of the many difficulties which have been overcome, and of those still awaiting solution. My purpose tonight is rather different. All who have been concerned with the operation of the flotation process must have wondered, like myself, why the process is possible at all. In particular, why can minerals which are heavier than water be made to l10at to its surface; why do certain minerals float while others do not; and what are the functions of the added chemicals?I have been asked to describe tonight some of the ways which have been adopted in the Melbourne University laboratory in an endeavour to find answers to these. questions. Knowing that you are just as interested in them as we are and, furthermore, appreciating that were it not for the co-operation of the Broken Hill companies our researches would not have been possible, I regard it as a high privilege that I should have been invited to tell you of our work. Before doing so, I would like to tell you the reasons why the work was started and for whom it has been carried out. Soon after the flotation process had been successfully exploited on a commercial scale a number of investigators sought to determine the theoretical basis upon which it rests, and our knowledge of the function of the added chemicals has been considerably broadened by the published accounts of many workers, particularly in recent years of those working in American universities.The Australian metallurgist played, as you know, a part second to none in the early development of the process, and Australia's mining fields had already reaped such rich rewards from it that, late in 1929, it was felt by some of the leaders of the industry that we should take a larger part in the efforts being made to extend the knowledge of the principles upon which the process is based.Accordingly, several companies - the Broken Hill South, the North Broken Hill, The Zinc Corporation, the Electrolytic Zinc and the Mount Lyell Companies - established a laboratory in the chemistry department of the University of Melbourne for the purpose of investigating the principles underlying flotation.Subsequently another British company, the Burma Corporation Ltd, expressed a desire to co-operate.

Jan 1, 1994

The Mount Morgan eopper-gold orebody is contained within a series of Mid-Devonian volcanics which occurs as a roof pendant within Permian granite. The ore minerals comprise pyrite, chalcopyrite, and local aggregations of magnetite and pyrrhotite. Silver-rich gold (electrum) is disseminated through the ore usually in ultrafine to sub-microscopic dimensions. Accessory minerals include marcasite, digenite, chalcocite, covellite, sphalerite, bismuthinite, molybdenite, calaverite, petzite, and cassiterite.Very minor accessories include cubanite, tetrahedrite, galena, arsenopyrite, hematiIe, goethite, and rutile. The gangue minerals are quartz, predominantly, with minor amounts of chlorite and sericite.Study of microtextures of a representative suite of specimens from Mount Morgan does not reveal any criteria indicative of metasomatic replacement but does show, in the case of pyrite, evidence strongly suggestive of annealing recrystallization. Other textures in pyrite indicate porphyroblastic growth of the iron sulphide.It is inferred that the Mount Morgan orebody is genetically related to the volcanic rocks and was later contact metamorphosed by the intrusive granite or by the series of intermediate to basic dykes that transect inmine area. On this basis the Mount Morgan orebody would be a contact metamorphosed volcanic hydrothermal deposit emplaced, according to recent studies, along a pipe-like zone of brecciation.

Jan 1, 1967

By Rosenblatt M, Gilroy J. A C Cunningham C V B

Vaal Reefs Exploration and Mining Company Limited operates one of the largest producing gold mines in the world. The annual production of 76 tons of gold from 12 million tons of ore treated is obtained mainly from underground sources. Daily some 6.6 km of stope face is blasted and 41 tons of explosives is used to break the rock. The mine employs 45 000 men of whom 35 000 work underground. The company operates nine large vertical shaft systems of which seven extend more than 2000 m below surface and an eighth, currently being sunk, will bottom at 3700 m below surface.

Jan 1, 1995

The development of present methods of pillar extraction has evolved from the very earliest of hand mining operations which were limited in scope by venti- lation and transport considerations. Conservation and safety considerations also have led to the current shortwall operations with conventional equipment and powered supports. The shortwall methods have had significant effects on safety, costs, con- servation, flexibility, and other aspects of pillar extraction. The present stage falls short of the ideal but is some guide to prediction in what direction may lie the ideal methods for the future.

Jan 1, 1974