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By Thomas D. Kelly

In 1900, the average U.S. citizen’s average life span was 47 years. He traveled about 1,900 km (1,200miles) in a lifetime and resided in a home with an ice-box for food storage and oil or gas for lighting. He communicated by mail, telegraph and crude telephones with limited availability and range. By 2000, the average citizen’s life span was 77 years. He traveled an average of 19,000 km/a (12,000 miles/year) by automobile alone. He resided in a home with many electrical appliances, including refrigerators and electric lights. And he communicated almost instantaneously with any other part of the globe by several widely available means, including portable phones and e-mail.

Jan 1, 2002

By J Dwyer, M Hill

Downer’s mining division has made an operational and financial commitment to developing engineered solutions that mitigate the risks associated with operator proximity to uncontrolled development drill boom movements, and unguarded rotating drill steels.With the potential for serious injury or fatality, these identified risks are categorised as critical. Previous attempts by the industry to engineer them out have produced limited success, with numerous incidents still occurring year on year. Ultimately, the industry (as a whole) remains reliant on procedural prevention for operator safety.Downer understood the success of such an initiative would largely depend on the effective collaboration between operational experience, technology experts and automation. With so many variables requiring consideration; such as physical operator movement, machine boom movements, variable machine positions, and underground environmental impacts – challenging traditional technologies was necessary to deliver an optimal solution.For that reason, discrete detection (similar to laser curtains or beams) was considered not fit for purpose. The use of situational mapping, using rotating lasers, however, provided the optimal solution. The lasers collect data that is then processed using a custom software application.The software application is specifically programmed for tracking and classifying objects within detection zones, using advanced algorithms and filtering. Recognition and removal of non-positive disturbances are possible without losing personnel detection capability. The detection of relevant classified objects (humans) is determined by analysis of object size, age, movement, and speed etc. When the relevant object is detected, an alarm and inhibit function is applied preventing drilling functions.Any breach of the safety zone (forward of the front jacks) will automatically disable the hydraulic boom function. This can only be reset in the cabin once the person or persons have returned past the front jacks of the development drill into the safety zone.Downer, in collaboration with partner YUMARR Automation, has successfully developed this reliable boom isolation system, and is called JumboGuard. The system has now been commissioned and installed across all Downer Mining development drill fleets, operating in Australia.CITATION:Hill, M and Dwyer, J, 2017. JumboGuard – automatic boom isolation system, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 287–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

In mining industries, materials loading and handling costs represent a significant component of the total (capital and operation) costs. A variety of methods have been applied in surface mine equipment selection in order to select the suitable loading and haulage system with the lowest total cost. The optimal size and number of equipment calculation are very important task for mining engineering because loading and haulage equipment are major proportion of open pit mining cost. Capital and operating cost are considered in objective function with respect to interest rate, insurance and tax in non-linear form. Shovel and truck annual productivity constraint, fleet matching constraint and number of truck per shovel constraint are incorporated in this optimisation problem with continuous variables. This formulation will yield total cost minimisation per hour and good accuracy compared to previous methods.

Dec 6, 2010

By Raymond J. Pichette

"Aeromagnetic data can be useful in helping to delineate structures and rock types in gold exploration. Magnetic anomalies associated with Archean volcanic belts in northeastern Ontario can be quickly and effectively analyzed in profile form with the use of model curves. The model curves help to locate contacts between strata. They also help to estimate the magnetite content of the rocks and their depth beneath overburden.An aeromagnetic map of part of Catharine Township, Ontario has been analyzed with the aid of model curves. Several magnetic rock types, potential fault zones and areas of relatively thick overburden were delineated.IntroductionIn any exploration program, a good understanding of the stratigraphy, rock types and structure enhances the possibility of success. For example, environments which host gold deposits in the Abitibi Volcanic Belt may be characterized as follows (Jensen, 1980; Pyke, 1980):(I) They have major faults, especially as tectonic boundaries between volcanic piles which include mafic and ultramafic rocks and clastic sedimentary rocks or gneisses.(2) They have subvolcanic felsic intrusions.(3) They have extensive carbonitization, with or without carbonate and sulphide-facies iron formation.In all cases, delineation of structure and rock type should be a major objective in exploration. The analysis of magnetic data can be a useful tool in this task. This paper is presented with the purpose of describing the application of the magnetic method to gold exploration in Archean volcanic terrains.Magnetic AnalysisTotal-intensity magnetic contour maps can be used to discriminate rock units according to differences in magnetization. However, because of smoothing of texture resulting from the compilation procedure and the fact that survey lines are widely spaced, contours should not be directly used for quantitative analysis. A much more definitive means of magnetic analysis is provided by the use of the original profile or chart recordings. Model curves provide a basis for analyzing these profiles both accurately and rapidly."

Jan 1, 1982

By Varadarajan Seshadri

Geometallurgical characterization of iron ore which is a raw material for Iron making as in the case of charcoal blast furnaces operating in Brazil or for production of agglomerates such as iron ore sinter which serves as burden material for blast furnces of high productivity or pellets extensively used in the direct reduction processes all over the world in the iron and steel industry. Selection of proper raw material after due characterization should lead to an improvement of the productivity of the respective processes The usual classification of quality of iron ore is uniquely based on chemical analysis, granulometric and physical parameters. However not much emphasis has been given to the structural characteristics which also are important in the processes. Different typological categories of Brazilian iron ores have been used in the characterization . For instance, several kinds of hematite crystals like specularite, martite and microgranular hematite, etc with variable crystal sizes are found in the different ore types. They are also composed of different of fabrics and types of accessorial mineralogical constituents and have different porosities, pore diameters, etc which influence the cold and the hot agglomeration stages of the ore fines, and also chracteristics such as reducibility, decrepitation etc, important for assessment of quality of iron ores. . The first step for attaining a good characterization of ores is to know in detail about the structure of the deposit, shape of the body, types of iron ores and their distribution. This requires a geological-structural study and the mapping of the bodies using mineralogical criteria for typological classification of ores. followed by structural characterization of materials in stages of mining, comminution, screening and concentration processes. In this contribution a geometallurgical approach for quality control of Brazilian iron ores for sintering and pelletizing processes is highligted.

Jan 1, 2006

An optical computing system was used to determine spacings and frequencies in geological fabrics and engineering joint fabrics.Three-dimensional arrays of joints were plotted on an equal-area net. Directions in which true spacings are seen were determined from these plots. Photographs taken along these directions were used for optical computing.

Jan 1, 1970

By J. N. Van der Merwe

The data base of failed coal pillars in South Africa was analysed with regard to the time of failure in an effort to develop a method to predict how long after their formation coal pillars will fail. It was found that meaningful results could only be obtained by splitting the data base up into groups that displayed similar behaviour. It was postulated, based on observation and experience, that coal pillars fail by a process of progressive weakening progressing into the pillar from the edges. Minimum pillar dimensions to ensure failure were calculated?these were the dimensions that corresponded to a minimum ?real? factor of safety. From the scaling distance required to reach the minimum safety factor, rates of scaling for the failed pillars were calculated based on the observed real lives of the pillars. It was found that the rates of scaling were unique for different mining areas and that they correlated directly with mining height and inversely with time. Using the derived scaling rates, the predicted pillar lives were back calculated for the pillars in the data base of failed pillars. In two of the three groups, the predicted lives correlated well with the observed lives on a one-to-one comparison. In all cases, the predicted lives were in the same time range as the observed lives. Overall, the frequency of predicted lives closely replicated the observed frequency of observed lives of the pillars in the data base of failed pillars. The method was successful in distinguishing between the data base of failed and a representative sample of intact pillars. While the predictions matched the observed lives of failed pillars, the predictions of expected lives for intact (hitherto unfailed) pillars were orders of magnitude greater. It is now possible to estimate the frequencies of future pillar failures for the purposes of mine closure and undermining of surface structures within broad bands.

Jan 1, 2003

By K. V. Phani Prabhakar, G. Padmanabham1, L. Subashini

Laser-arc Hybrid Welding (LAHW) is a relatively recent concept which effectively combines the advantages of laser welding such as the high depth of penetration, low heat input, high welding speed and the positive aspects of arc welding such as better edge bridging and possibility to add filler. For example, steel sections upto 12 mm thickness have been successfully welded in a single pass at a welding speed of 1 m/minute using a 3.5 kW CO2 laser in combination with a MIG arc. Maraging steel of grade M250 is widely used in the aerospace industry in thicknesses upto 10 mm. Conventionally, it is possible to MIG weld such thicknesses in 3-5 passes employing V-Groove joint preparation. However, this multi-pass welding results in formation of reverted austenite in the weld zone after post weld aging; and the high heat input widens the reverted austenite containing heat affected zone which is popularly known as the dark zone/eyebrow zone. Both these zones are detrimental to strength of the welded joint, specifically the fracture toughness. The width of the dark band is an important factor because, thinner the band, it is supported more effectively by the surrounding material. Therefore, in order to avoid multi-pass welding and reduce the overall heat input, single-pass laser-MIG hybrid welding was attempted on 10 mm thick maraging steel M 250 plates using a hybrid laser arc welding system comprising a 3.5 kW CO2 slab laser and a MIG welding system. Simultaneously, multi-pass MIG welds also are produced. Both the laser-MIG hybrid and MIG welds are characterized microstructurally and subjected to mechanical tests such as tensile and fracture toughness in as-welded and post weld aged condition. The amount and distribution of reverted austenite in the fusion zone and width of the dark band was found to be different. Hybrid welds showed a narrow dark band zone and improved mechanical properties. Laser-hybrid and MIG welding investigations carried out on thick section maraging steel M 250 will be presented in detail, including microstructure, tensile properties and fracture toughness of the welds. To the best of the knowledge of the authors there are no reports on laser-MIG hybrid welding of maraging steels.

Jan 1, 2014

By Magnus Ruin

The dry deep mixing method for stabilization of soft soil has been used in the Scandinavian countries for 25 years. The typical application has been stabilization of soft inorganic clay. Today the method is used more frequently in organic soil with good results. The Limix System, introduced in the USA by Hercules Grundläggning AB and TREVIICOS Corporation, is a cost-effective dry deep mixing method used to stabilize most types of soft soil. This paper presents the general principles of stabilizing organic soil with the dry mix method and two case histories of soil stabilization projects in organic soil. Between October 2000 and June 2001 the Limix System was used in England to stabilize soft organic alluvium at the Channel Tunnel Rail Link, Contract 440. During year 2000 the Limix System was used in soft organic soil in Holland near the Groene Hart Tunnel entrance to support trench excavations for slurry walls and concrete barrettes.

Jan 1, 2001

By Doris M. Hyde

In the past, mining has represented between 11% and 12% of the gross domestic product (GDP). In 1982, mining contributed over $150 million to the estimated $1.4 billion GDP.2 Overall economic growth for 1983 was projected at about 2%, primarily as a result of increased tourism. The inflation rate remained at or fell below the 1982 level of almost 4%. The Government continued its efforts to strengthen the industrial base by improving infrastructural systems and the establishment of a free trade zone. Laws against property ownership by foreigners or foreign-owned companies were strengthened, but the prohibition was softened to allow for close family inheritance. Otherwise, Government approval must be obtained to retain property acquired through inheritance, court order, mortgage, or other means. Special consideration was granted to foreign investors seeking to promote industries beneficial to the economy.

Jan 1, 1985

By S. M. Shelton, A. L. Engel

"This report presents the results of investigations of ore-testing projects assigned to the Ore-Dressing Section, Metallurgical Division, Bureau of Mines, at the Mississippi Valley Experiment Station, Rolla Mo. During the fiscal year ended June 30, 1941.The manner of approving ore-testing projects has been explained in a previous reports. 4/ The testing procedures likewise have been described. 5/The treatment methods described are based upon laboratory experiments with small amounts of sample and naturally are subject to the inherent, normal, limiting conditions of such procedure. It is not intended to describe treatments in detail, but rather to indicate applicable methods. Local operating conditions, when the laboratory results are applied to plant operations, may require further study. Large-scale pilot-plant tests should be made before commercial operations are begun, so that translation from the experimental stage will yield satisfactory results."

Mar 1, 1942

By F. D. Ford, Z. Dai, A. Byers

Manitoba Mining and Milling operations consist of three underground mines (Thompson T1, T3 and Birchtree), feeding the Thompson Mill. Three years ago, a collaborative effort involving Mines Exploration, Mines Project Development Group, Mill Technical Services and Vale Base Metals Technical Excellence Center was initiated to establish and verify the cause of high variability in concentrate quality and Ni recovery at the Thompson Mill. One outcome of this work was a program to systematically characterize the mineralogy and metallurgical performance of current and future orebodies feeding the mill. Mineralogy results show that high value enabling ores typically have a high pentlandite to pyrrhotite ratio and benign silicate mineralogy (mostly quartz and feldspar from sedimentary host rocks), while metallurgically challenging ores contain some combination of pyrite and/or hexagonal (non-magnetic) pyrrhotite and/or elevated quantities of talc (with associated carbonates) derived from altered ultramafic host rocks. The metallurgical performance of these two ore types has been simulated by an Excel particle flotation model, which calculates the relative floatability of particles based on the particle’s mineral composition and mineral locking determined from MLA images. The relationship between these mineral properties measured by MLA and metallurgical performance was established using 13 monthly composite samples from Thompson Mill. The model was then validated with results of laboratory flotation experiments on individual orebodies submitted for evaluation. The validated model can be used to predict plant metallurgical performance based on individual ore bodies feeding the mill. Individual orebody’s grade-recovery curves are assumed to be additive, and can be weighted in proportion to the mill feed to predict mill recovery over the same time period. The ore mixing can be done with a simple Excel spreadsheet and comes with a graphical output for easy visualization of the resulting grade-recovery curve.

Jan 1, 2015

By A. F. S. Schoukens

The Mintek Thermal Magnesium Process (MTMP) was successfully demonstrated in November 2004. The pilot plant was operated continuously for 8 days, during which about 30 tons of magnesium producing recipe was smelted in a DC (direct-current) arc furnace at a feed rate of 525 kg/h. The furnace was operated at power levels of 700 to 850 kW, resulting in slag tapping temperatures of 1600 to 1700°C. Magnesium extraction averaged 77 per cent and was as high as 85 per cent during good extraction periods. The furnace generated 70 to 85 kg/h magnesium vapour that was delivered to the condenser where the temperature was controlled at 680 to 720°C. The novel condenser captured the magnesium in a liquid state, which was tapped periodically as required. In total, 15 magnesium-tapping operations were carried out, proving that online magnesium tapping can be consistently performed without any major difficulty. About 3500 kg of crude magnesium was produced with a quality that was similar to, if not better than, that of the Magnetherm?s crude metal. The condensation efficiency averaged 85 per cent, and peaked at 87 per cent, which exceeded the target of 80 per cent set for the pilot scale. A brief magnesium market study was also carried out. Magnesium demand is expected to keep on growing by 6 to 8 percent over the next 10 years and could reach 2 million tons by the year 2020. The growth will be mainly in the die-casting sector for light-weight automotive applications. China is likely to remain the dominant supplier of primary magnesium but competitively priced non-Chinese magnesium producers will be needed to sustain the anticipated growth of 6 to 8 per cent over the next 10 years. In addition, a prefeasibility study was undertaken for a commercial plant. The study confirmed the relatively low capitalcosts of the MTMP process, as well as the competitiveness of theoperating costs, as compared to the industrial electrolytic process.

Jan 1, 2006

By H. Do, R. Yoon

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 to 100 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2007

By C. J. Allen, L. Battiston

"Introduction It has long been recognized by the hot-dip galvanizing industry that the characteristics of the galvanized coating can be influenced significantly by steel and pro cessing variables. Probably the variable of most concern to galvan izers today is steel chemistry. More specifically, the problem is the excessive reactivity of continuously-cast, silicon-bearing steels. In the past, structural steels processed by general galvanizers were in the low-to-medium ca rbon category and contained silicon at either low impurity levels (as with rimmed steels), or less than approximately 0.10% (as with semi-killed steels). The structures of the coatings produced on such steels are characterized by dense, compact layers of delta and zeta iron-zinc alloy phases and a distinct outer layer of eta zinc, which usually imparts a bright shiny appearance to the coating. The presence of silicon in steel, above the so-called semi-killed levels, is known to cause marked stru ctural changes in galvanized coatings. Such coatings are characterized by a relatively thin delta layer, a thick , coarse zeta layer and frequently an absence of the eta layer. The eta phase, comprising zinc which is carried out of the bath during withdrawal of the work, can be consumed by the continuation of the coating reactions until its temperature drops to the solidification point. This results in a dull grey and often mottled surface instead of the usually bright metallic appearance. These galvanized coatings are usually much thicker than coating specifications requ ire and they are usually more brittle and have poor adhesion to the steel. In service, these coatings tend to develop a rust-like discolouration. With the wider use of continuous casting by the steel producers and the associated additions of silicon in this process, the problem is becoming more important and receiving greater attention from the galvanizing industry ."

Jan 1, 1987

By Li-ming Qi

During mining, the stress in the coal face varies, and, at the same time, the gas flows from the coal body into the excavation, which will cause the gas pressure to change continuously. Assuming the coal gas content of the coal to be constant, and applying the law of energy conservation, the influence of stress concentration on the gas pressure was analysed. It was found that the stress is proportional to the gas pressure. Finally, as a result of analysis and the law of gas flow, the gas pressure dynamic distribution ahead of tunnelling was modelled, and the mechanism by which blasting induces outburst was explained by making use of the model. Keywords: gas pressure, stress concentration, excavation, tunnel.

Jan 1, 2007

By Lindsay D. Norman

Computer models for simulating the construction and for calculating the properties of particulate solids in two- and three-dimensional systems (coverings of circles and packings of spheres, respectively) were developed. By simulating the physical process of constructing circle coverings and sphere packings, in which the circles or spheres were randomly selected from many different distributions of sizes, physically realizable loose random assemblies were simulated whose physical and geometrical properties were predictable with the computer. Many of these properties, such as the number of contacts, are extremely-difficult to measure accurately, or considerable ingenuity is required in their determination. All of these properties were easily and accurately calculated by the computer models for many different coverings and packings constructed from equal, discrete, uniform, and log-normal distributions of particles. In addition to the loose random assemblies, dense random covering and packing constructions were simulated whose properties are ideal upper limits for those of the loose random coverings and packings. The properties of the dense random coverings and packings, heretofore only obtainable by theoretical analysis, were also simply obtained. The statistical geometry of loose random coverings and packings was studied, and several new interpretations of the area-covering or space-filling requirements in these systems were made. In two dimensions, it was found that the properties of all loose random coverings are predictable by taking suitably weighted averages of the corresponding properties of just four kinds of polygons whose edges are defined by connecting the centers of mutually tangent circles in the covering. The distributions of these polygons that permit area-covering were determined, and empirical equations for predicting the density, average coordination number, and average pore area in loose and dense random coverings were formulated. The properties of loose packings were determined by performing a simplicial division of the computer-simulated assemblies to produce a unique set of minimum volume, space-filling tetrahedra whose edges connected the sphere centers in each packing. A simple empirical equation was formulated that permits the calculation of the average number of contacts in any sphere packing, random or regular. Some of the statistical geometrical properties of the simplicial tetrahedra in the computer-simulated packings were analyzed. The tetrahedron edge length distributions in all the loose random packings were nearly identical when the edges were presented in terms of sphere diameters, regardless of the sphere population in the packing. Moreover, the gap lengths in the loose packings were to an excellent approximation representable by a uniform distribution of sizes. The distributions of spheres in tetrahedra resulting from the simplicial division of the loose random packings also existed in the tetrahedra in dense random packings. These observations were employed in developing a unique method for predicting the geometrical properties of loose random packings without simulating the assembled packing. Instead, the space-filling simplicial graph could be predicted for any given density of packing of any sphere population. The cumulative packing properties of these tetrahedra were shown to be nearly identical to those calculated by all loose random packing simulations attempted in this investigation. The simplicial tetrahedra completely describe a packing and can therefore be used to predict all properties of interest.

Jan 1, 1971

By John E. Leitch

The cost of corrosion as measured by such cost components as the renovation or replacement of coated steel, or the use of expensive coating systems on steel, is considerable. Extrapolating from figures for the USA would place the overall cost of corrosion for South Africa as a figure of the order of magnitude of something over 1% of the GNP. This is a sizeable amount, of which costs associated with atmospheric corrosion would be a significant proportion. The corrosivity of an atmosphere can be defined as the ability of the atmosphere to cause corrosion in a given metal or alloy (International Standards Organization [1]). The ISO Standard 9223 specifies the key factors in the atmospheric corrosion of metals and alloys, and defines categories of corrosivity on the basis of these factors. Prior to the publication of that ISO standard, Callaghan published the results of his twenty-year exposure programme and his excellent corrosivity map of Southern Africa [2]. The present author published updates of the corrosivity map in 1999 [3] and again in 2003 [4]. The summary of the individual areas of corrosivity around Southern Africa was published in the latter paper, and is reproduced here as the following TABLE 1. Of significance in TABLE 1 are the numerous regions of very high corrosivity (C5 or beyond), particularly the rural West Coast shoreline, the North East Coast (KZN) shoreline, and the coastal cities Cape Town, Durban and Richards Bay. The corrosivity map as published is obviously based on much extrapolation as only a small number of points have been measured. During the past three years further measurements have been made, mostly however at the same sites in order to give greater reliability and to monitor long-term trends with changes in pollution. These two aspects are incorporated in this update. There has become available a greater amount of air pollution data for centres in South Africa than was the case some years ago. In this present paper the pollution data are used to extrapolate the corrosivity over areas where little or no direct corrosivity measurement has been made. This methodology is described in ISO 9223.

Jan 1, 2006

By Pierre Pelletier, Julie Fournier, Gianni Bartolacci, Yves Breau, Dominique Girard, Ahmed Bouajila, Carl Duchesne

"The development of on-stream analyzers (OSA), such as those based on X-ray fluorescence (XRF), has been key to improve metallurgical performance of flotation processes. However, since these analyzers are shared between several streams, they typically provide grade measurements every about 10-15 minutes. In general, this frequency is too long compared to process dynamics and so, implementing an efficient feedback control strategy based on OSA can be difficult. In addition, due to the limited capacity of OSA systems, several important intermediate streams are not analysed, but could provide relevant information about the state of a flotation circuit.To overcome this problem, vision systems have been developed in the past to predict concentrate grade based on froth color – this could be very useful to control flotation performance between OSA measurements. However, applications reported in the literature typically use univariate summary statistics of the full red, blue, and green color distribution of froth images, while RGB images are truly multivariate. Although, in some cases, grade prediction was achieved with reasonable accuracy, one may, by using only summary statistics, miss important information about the state of the flotation process.This paper investigates the application of Multivariate Image Analysis (MIA) concepts to flotation froth images. These techniques are based on multivariate statistical methods such as PCA and PLS, which have the ability to analyze large databases (such as digital images) and summarize the relevant information content of the data into a small number of latent variables, capturing the most important features of the images for concentrate grade prediction. The potential of application of these methods in the mineral processing industry is illustrated using a few industrial case studies."

Jan 1, 2003

By M Gabbitus, B Young, T Lukins, M Slater

This paper details the implementation of a new type of grade control system at the Black Star open cut mine in Mount Isa, Queensland. It explores the site requirements for grade control, what as previously in place and what the site required moving forward. It also details some of the features of the system installed and why it was chosen over other grade control systems available. Black Star open cut mine has been in operation since late 2004, and was developed to extract the surface extents of the Ag-Pb-Zn mineralisation previously mined in the Isa Lead Mine. Black Star is currently mining seven distinct orebodies in and around active void hazard zones and hence, its grade control requirements are very detailed and complex. The implementation of a new system to manage the model update and block out processes was, therefore, of critical importance to the site and required a detailed understanding of the requirements of the entire mining team from drilling through to geology, survey and production. Having previously run the grade control process using site specific æblack boxÆ scripts and macros, Black Star needed to implement a more open, auditable and flexible system, which allowed the geologists to control the process and make strategic changes as the situation demanded. MineSightÆs Axis Grade Control, with its flexible, generic framework for managing the process, met these demands. Being an out of the box solution that requires minimal setup and training was also a key factor in the decision to use it.CITATION:Lukins, T, Slater, M, Gabbitus, M and Young, B, 2012. The introduction of axis at Black Star Open Cut, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 71-74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012