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The effects of changes in sintering bed height, coke fuel, suction and basicity on sinter productivity, physical strength and mineralogy were determined. It was found that, for a given iron ore, there is a narrow -coke range which maximises sinter strength, irrespective of bed height (in the range 300 to 500 mm) or basicity (in the range 1.2 to 2.2). Increases in bed height, at a constant coke level, improved the physical strength of the sinter. Productivity increases were obtained by increasing the sintering suction but, at coke levels other than the optimum, these *ere somewhat offset by the decrease in sinter physical strength. At basicities higher than 1.2 (i.e. 1.6, 1.8 and 2.2) there was a narrowing of'the size range of product sinter, with a decrease in the percentage of top size material, and a decrease in the amount of fines produced. Changes in coke, bed height and basicity exert major effects on sinter mineralogy, while the Nagoya index was mainly influenced by cote and bed height Changes.

Jan 1, 1975

By S Larbi-Bram, F Shi, E Manlapig

Mining companies have recognised that characterisation of particle breakage plays an essential role in the design and optimisation of comminution circuits. Recently the JKMRC comminution research team has developed a new breakage model incorporating the effect of particle size, and a new breakage characterisation testing device, called the JK Rotary Breakage Tester (JKRBT), which allows rapid testing of particle breakage under high energy single impact and low energy repetitive impact conditions. The latter is believed to be the dominant breakage mechanism in AG/SAG mills. Existing devices, such as the JKMRC Drop Weight Tester, are not suitable for performing repetitive impacts since they are too time consuming. Positive feedback received from mining company sponsors to the new technology has prompted the JKMRC to further validate the device and the model through a formalised experimental test program on professionally designed and manufactured JKRBT machines. The first JKRBT was installed at the Anglo Research laboratory in Johannesburg in March 2007 and four more major mining companies will participate in the project in 2008, with commercial release expected in early 2009. The JKRBT has the potential to revolutionise ore testing, with applications in laboratory impact breakage characterisation of rock samples, drill cores, coal and other materials. It also stands poised to significantly advance the process control of comminution circuits since it is readily adaptable to on-line ore hardness measurement. Can any mine afford to miss out on this technology?

Jan 1, 2008

By A T. Bernardes

Using the cellular automata computational technique it was possible to simulate the generation and discharge of an iron ore pellet pile inside a direct iron reduction oven, as well as to calculate the reduction degree of the pellets as they leave the oven. It allows simulation of the variation of operational parameters and verify the results of those variations in the pellet reduction degree. The simulated data was validated in two instances: for the dynamics of the pellet flow inside the oven it was used in an acrylic bi-dimensional silo; and data from direct reduction iron literature was used for validation of the pellet reduction. The simulated results were considered acceptable to describe the movement of the iron pellet inside the direct reduction iron oven and to describe the iron pellet reduction direct in the oven.

Sep 26, 2011

The mobility of radionuclides released into aquatic, terrestrial and subsurface environments by mining, industrial processes is an area that deserves significant scientific attention. The presence of microorganisms in these environments can influence the transport of radionuclides. Free-living microorganisms constitute mobile suspended particles that may have a radionuclide sorbing capacity higher than that of the environment. Radionuclide transport will then proceed faster with than without microorganisms. In contrast, if the majority of the microorganisms are growing in biofilms on surfaces, transport of radionuclides may be reduced. Microorganisms can directly sorb radionuclides either within the cell structure or on the cell wall. Radionuclides could also be sorbed by minerals precipitated by microorganisms. Microorganisms produce complexing agents that can influence radionuclide mobility. The involvement of microorganisms in biogeochemical processes is related to their ability to include various chemical elements and their combinations into biochemical redox reactions. Microorganisms can alter the extent of radionuclide oxidation that results in their deposition as a result of the formation of insoluble forms. Some studies have shown the bioremediative potential of stimulating reducing bacteria to use some of the soluble radionuclides as electron acceptors and thus precipitate them out of solution. The microbial involvement in providing a barrier for radioactive element migration (uranium, technetium) and the formation of ores (eg uranium) has been justified. The mediated impact of microbial activity on radionuclide migration occurs through its effect on the ambient geochemistry by geochemical speciation changes, pH changes and changes to the ambient redox potential. As the mobility of many radionuclides depends on the pH and redox potential of the environment, these microbially mediated geochemical changes can influence radionuclide migration through changes to both the dominant radionuclide species and mineral phases.

Jan 1, 2004

By Y B. Kang, Y J. Park

Ti-added ultra-low carbon (ULC) steel is produced by adding Al and Ti during the secondary refining process to deoxidise molten steel and to bind C and N which are detrimental to the deep drawing quality of the steel product. However, the production of Ti-added ULC steel faces challenges, including submerged entry nozzle clogging and surface defects on cold rolled coils. The troubles were often attributed to ‘Al-Ti complex inclusions’ in the molten steel. However, the evolution of oxide inclusions including their stability has been still unclear. In the present study, the evolution of these inclusions in Ti-added ULC steel was investigated by phase diagram measurement, CALPHAD thermodynamic modelling, high-temperature stability test for the oxides, and observation of transient behaviour of oxide inclusions in the steel. The phase diagram of the Al-Ti-O system was elucidated with an emphasis on oxygen potential, which significantly controls the stability of the oxides. CALPHAD thermodynamic models and a self-consistent database were developed. The transient behaviour of Al-Ti complex inclusions in Ti-added ULC steel was observed in situ using a confocal scanning laser microscope. This was additionally validated by the new thermodynamic model. The equilibrium phases of the oxide inclusions were investigated using a high-temperature resistance furnace, and were analysed using a secondary electron microscope, energy dispersive spectrometer, and electron back-scattered diffraction. By considering the morphology and crystal structure of these inclusions, the evolution of Al-Ti oxide inclusions was elucidated. Various behaviour of Al-Ti inclusions and their influence on steel cleanliness are discussed.

Aug 21, 2024

By Pak DL

Over the last decade computers have become an essential element in assessing the economic feasibility of mining new mineral deposits and in assisting a variety of related support functions. A broad overview is given of the many technical application areas where computers are contributing to the mining industry with reference to work being done on the evaluation of drill hole information, mineral inventory modelling, ore reserve estimation, financial analysis, process simulation, process control, workshop job scheduling, PERT applications, and com- puter aided drafting. In all these areas the computer has greatly reduced the manual effort involved in looking at alternatives. It has had a significant effect in eliminating delays in revising calculations, or rescheduling activities to incorporate new data or cater for changing conditions, while at the same time providing more accurate and prompt information for the management decision making Process.

Jan 1, 1980

By A Karrech, E Hamdi

The uncertainty of geomaterials properties is commonly encountered in resource engineering applications, especially in mining engineering where the rock mass texture, joints, fractures and damage zones can impose the mining method and operation cycles. In the present research work, we focus on the elastic properties of rock masses. We use stochastic numerical simulation of fractured rock masses to estimate their Young moduli. The procedure starts with field mapping campaigns which are conducted to evaluate the locations, dip angles, strike and trace lengths of pre-existing fractures. We develop statistical law parameters of the natural fracture network to represent the weakness patterns. In addition, we use HLA-Dissim, a recently developed and validated Matlab program, to simulate the propagation of monochromatic longitudinal waves and derive the equivalent elastic modulus of fractured rock masses. Such procedure applies within a simulation domain, which is greater than an Elementary Representative Volume.At a second stage, we conduct finite element simulations to validate the previous approach. The matrix and the actual fractures zones are reproduced in the model to mimic the natural set-up. The block is excited on particular positions and its response is evaluated on predefined spots. Real field rock fracture mapping data and monitored single-hole blast induced vibrations are used to validate the theoretical and numerical approaches discussed herein. Comparison between the simulated and measured vibration records shows a great agreement which confirms that the proposed methodology has a full potential to predict and optimise multihole/multidelay blast-induced vibrations.CITATION:Hamdi, E and Karrech, A, 2015. A methodology for rock mass characterisation to control blast-induced vibrations, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 89–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By C E. Loayza, R M. Pinto, J G. G=mez

The Yanacocha District is located 20 km north of the city of Cajamarca, in the Northern Andean Orogenic belt of northern Peru.Gold production may have occurred as early as Incan times (Paverd, 2000), but modern exploration that began in the 1960s targeted only copper and silver. Newmont Mining Corporation, BRGM and Compa±fa de Minas Buenaventura began exploring for gold in 1983, with Newmont as operator.Initial drilling took place in 1985. By 1992 a reserve of 1.28 million ounces was reported (Teal et al, 2002).Production began at the Carachugo deposit in 1993.Current reserves are 31.7 million ounces at $US 325 per ounce at a grade of 1.03 ppm (Newmont Annual Report, 2003).The operating company, Mineral Yanacocha SRL (Newmont 51 per cent, Buenaventura 44 per cent and International Finance Corporation five per cent) produced 2.85 million ounces in 2003, making Yanacocha one of the largest gold mining operations in the world. The district is made up of a series of epithermal, high sulfidation style gold deposits and one gold-rich gravel deposit (La Quinua), aligned in a NE trend.La Quinua is not discussed in detail in this paper. The bedrock deposits are hosted in a Miocene volcanic package, the Yanacocha Volcanic Complex that also trends NE.Re gional NW striking Andean faults intersect the NE striking Trans-Andean Chicama-Yanacocha structural corridor (Turner, 1997), localising the district mineralisation. These two structural orientations dominate the district, controlling breccia and intrusion locations, and gold mineralisation. Discontinuous EW oriented fracture zones are interpreted as extensional and locally are important in controlling gold mineralisation.

Jan 1, 2004

Byproduct coking is practised in three of the major Australian ironmaking centres, the Newcastle and Whyalla works of the Broken Hill Proprietary Co. Ltd. and the Port Kembla works of Australian Iron & Steel Pty. Ltd. Coking first commenced at Newcastle in 1915 and at Port Kembla in 1938. The installations established at these centres include coal cleaning facilities and com- plete byproduct streams. The Whyalla plant, because of its location is somewhat less extensive, having no coal cleaning plant and a comparatively restricted byproduct section. As new batteries have been built every opportunity has been taken to incorporate modern design features and improved operat- ing techniques. This has included the provision of equipment to reduce atmospheric and water pollution. A marked reduction of markets for byproducts has had serious repercussions on the profitability of this section of the Industry.

Jan 1, 1972

Through the stress synthesis of many examples of macrostructure in the middle of China, it can be concluded that in the middle of Chinesetectonics there are two compression-torsion-forces, one of which ( from NW to SE ) came from the northwest side of Aerjinshan abyssal and giant fault("F1A", see Fig.7,8,9 ); the other (from S to N ) came from the south side of the north piedmontal fault of Kunlunshan-the south piedmontal fault of Qinlingshan ("F2K-F2Q", see Fig-7,829 ).Owing to the two compression torsion forces a new special type of structure named rotation-apart structure occurred from Chaidamu basin to Hebai, Henan, Anhui plain,from Caledonian movement, Hercynian movement,Yenshan movement to Himalayan movement, step by step In the north of Qilianshan during the late Caledonian movement: during the Hercynian movement it extended into a vast area including the Chaidamu basin and Eerduosi basin; during the Yenshan movement it spread over the whole area of Helanshan,Eerduosi basin and Hebai , Henan, Anhui plain. In the period of Himalayan movement all these structures revived .The rotation-apart structure controlled the distribution of all mineral deposits and also were the mineralizing structures.The relation between these rotation-apart structure and earthquakes is very close.

Jan 1, 1990

Tokyo Metropolitan Government designs the stormwater storage plans in underground, as a measure of flood control in completed urban district and improvement of combined sewarage system. This time, introducing those plans, we report about IKEJIRI and SIN-KOMAZAWA STORAGE TRUNK LINEs design and construction. They are located in Meguro river basin of the Morigasaki drainage area. Both storage trunk lines have capacity to store 15O,000m3 of stormwater. They are in use for countermeasure of flood till Meguro river's strengthening (intensity 50 mm/h) is ended. And after the strengthening, they will be in use for improvement of river water quality, through the storage of combined sewage and first runoff, which, otherwise overflows weirs and flows to river in a rainy day. These storage trunk line's full length is about 5700m. Boring diameter 66140 mm (f = 2672m) and 47800 mm (I = 2866m) of these tunnels are constructed by Mechanical Shield tunnelling method. And boring diameter 3600 mm x 4000 mm (R = 180m) is constructed by NATM tunnelling method. We began works in 1983, and have a mind to complete in 1987.

Jan 1, 1987

By S G. Gatehouse

Extensive gold mining activity û dominantly alluvial û has taken place in the Sofala-Wattle Flat district since the 1850s.This work will have located most, if not all, of the visible sources for the gold in current stream systems.Also, there are many gold bearing elevated Tertiary alluvial terraces in the district which may confuse possible gold signals from primary hard rock sources in the streams.Associated element signatures eg As and other chalcophiles, will discriminate non-alluvial signatures but will not necessarily distinguish non gold bearing mineralisation.Both trace elements and conventional gold analyses will dominantly re-identify known occurrences. Conventional BCL sampling is considered misleading as experience from the Oberon area to the south of Sofala demonstrated that BCL sampling was very sensitive û perhaps too sensitive.All occurrences û major or minor û of gold will be detected (Gatehouse, 1992). To improve on BCL sampling, a small, -120# sample with selective duplication was recommended to screen coarse-grained gold anomalism and a program of sampling covering an area thought to be prospective was enacted.Samples returning anomalous Au were analysed in duplicate and if the results demonstrated reproducibility, indicating fine gold only, the sample site was assigned a high priority.It was found that most of the reproducible samples clustered in one area û Spring Gully. The results of this sampling program led to immediate identification and, ultimately, the successful delineation of the Spring Gully gold deposit near Wattle Flat.

Jan 1, 2004

In the humid, subtropical climatic conditions, typical of Papua New Guinean high-lands, auriferous carbonate-quartz lodes and stockwork veins of the Upper Ridges mine at Wau, have weathered in situ forming manganese dioxide-quartz wad flatmakes and veins. Vein assemblages and sulphidized host breccia have been chemically weathered to 20-25m depth, and microscopic grains of electrum (550-600 fine) formerly enclosed in carbonate, sulphide and quartz have dissolved in the oxidizing alkaline fluid. Coarse secondary electrum, crystalline and dendritic, is concentrated by manganese dioxide and at the base of chemical weathering. Fineness is unchanged, eliminating the possibility of gold and silver migration as a chloride complex. Experimental tests on the stability of thiosulphate, and its ability to dissolve gold and silver from colloid, crystal and synthetic alloy confirm that secondary electrum at Upper Ridges is most compatible with precipitation from (Au,Ag)(S203)23-; a complex readily destabilized in the presence of MnO., or with decreasing Eh.

Jan 1, 1984

By J Knecht, R Klymowsky, E Burchardt

The wide spread introduction of SAG mills into grinding circuits 20 years ago was the last development which had a major impact on the design and economics of comminution circuits. Single SAG mills were able to replace batteries of high maintenance and cost intensive crushers in order to achieve high throughput operations. Today, where the head grades of gold and copper ores are falling, there is again a strong need for a significant breakthrough to reduce investment and operating costs as well as improve metal recoveries. High-pressure grinding rolls is the new technology available to meet this challenge. HPGRÆs are state-of-the-art in several mining and minerals applications such as the grinding of iron ores and concentrates, and diamond bearing ores. Reasons for their success in these industries are overall cost reductions and improved product properties achieved by the application of high compressive forces. But these ores are relatively soft, with unconfined compressive strengths up to 150 Mpa.

Jan 1, 2000

The Beverley uranium mine û now in production in the remote north of South Australia at1000 tonnes per annum û was established to meet a projected, but little-recognised shortfallin primary supply of uranium for the nuclear industry in the early part of the 21 st century. Inthe context of AustraliaÆs lack of bi-partisan support for uranium mining and the nuclearindustry, a four to five year window of opportunity existed from 1996 to establish the mine.During this period, Beverley achieved a number of firsts including: the first ISL mine inAustralia; the largest ISL mine in the world and the first to produce more than 500 tonnes ofuranium in its first year; the first to be established under a new Native Title regime in SouthAustralia; and the first to be established under a revised South Australian Mining Act.Beverley was brought into production against the background of: hostile opposition fromanti-nuclear activists; a suspicious and at-times hostile media; a regulatory and politicalcommunity that was unfamiliar with ISL mining; commercially unsophisticated Aboriginalgroups; an inexperienced engineering industry; and the vagaries of development in a remote,semi-arid location with neither population nor infrastructure. The lessons that can be learnedfrom Beverley showed that û like much in life û flexibility and timing are crucial.

Jan 1, 2002

Due to collapsing copper prices during 1974/75, a rapid changeover was made at the C.S.A. mine from mechanised cut and fill stoping with incline access to the more economic long hole open stoping method. In 1974/75, 20 per cent of total production came from open stopes. For the 1976/77 year-to- date, more than 80 per cent of total production has been won from open stopes. As a result, mining performance has improved considerably. Stops, drilling performance has increased by more than 50 per cent since the changeover from extension rod, 50 mm diameter cut and fill uphole drilling to 115 mm diameter in-the-hole hammer drilling of holes up to 65 m long. Stops blasting performance has improved from 750 tonnes to 950 tonnes blasted per manshift. Open stope primary blasting per- formance is much higher, but reduces to 950 tonnes per manshift when secondary blasting and firing of hung drawpoints are taken into consideration. Ground control, the most expensive and least productive aspect of cut and fill mining, is almost entirely eliminated in long hole open stoping.

Jan 1, 1977

In line with the recommendations of The AusIMM/AMIC Joint Committee Report in 1981 Isa Mine ore reserves are quoted in proven and probable categories (recoverable ore reserves). Internal reporting considers geological mining and extraction reserves in terms of proven and probable categories. Proven reserves are subdivided into detailed and confirmed ore. External reporting includes a possible ore category (not a reserve). The basis for these divisions is the spatial distribution of sampling data. Proven ore is defined by data 80m apart or less and probable ore by data 80m to 150m apart. Within the proven ore category detailed ore is defined by data 40m apart or less and confirmed ore by data 40m to 80m apart. Kriging is used to provide tonnage and grade information for the currently producing 1100 and 1900 orebodies. Kriged cross sections are initially produced to coincide with existing geological sections and are used for stope design. Stope ore reserves calculations are ideally performed at three discrete design stages, which in order of increasing accuracy are: preliminary design (PD), final design (FD) and ring design (RD). At each of these stages Kriged meshes incorporating the most recent sampling information are produced for reserve calculations. Historically derived mining and extraction factors are applied both to global reserves and individual stope reserves to reflect changes in geological and mining conditions as well as the sequencing of extraction. These factorised reserves are then inserted into the computerised reserves inventory system (RIN). Monitoring of individual stope performance continues into the production stage with input from planning, research, survey and production personnel. This allows actual extraction factors to be derived for comparison with predicted factors, providing some measure of stope performance.

Jan 1, 1987

Lihir Gold Mine is situated in a dormant volcanic caldera on a small island off PNG. Not æextinctÆ but dormant. Current ground temperatures are up to 150 degrees Celsius with active geysers in the workings of the mine, pools of boiling ground water adjacent to low-grade dumps and hydrogen sulphide gas emissions. It is a unique mining environment by world standards. This paper will deal with the following issues encountered and managed by the operation:blasting in hot and reactive ground; management of sulphide gas emissions; disposal at sea of all mining waste rock; one dear to all Australian minerÆs hearts û dealing with landowner groups; and unusual human resource issues.

Jan 1, 1999

By R Bresca, A McCallum, J Scealy

The Endeavor Mine, located to the north of Cobar, New South Wales, was purchased by CBH Resources Pty Ltd in September 2003. The operation has been producing lead and zinc concentrate continuously for over twenty-three years. In 2004, a water management program was instigated to improve the raw water use efficiency of the mining operation. The water management program involved the establishment of a Water Management Committee, a review and quantification of water use across the site, investigation and implementation of efficient water use practices, and workforce awareness training. The program has seen the amount of water used per tonne of ore milled reduced from an average of 1.08 kL/t in the March 2004 quarter, to 0.68 kL/t in the March 2005 quarter. This paper outlines the Endeavor Mine water management program and may serve as a model for other operations that are planning to improve their water use efficiency.

Jan 1, 2006

The mineralised members of the Brockman Iron Formation mined at Mt Whaleback are overlain and underlain by shale horizons. To maximise resource recovery, waste movement within the life of mine plan includes mining of the:unmineralised banded iron formation (BIF), Mt Whaleback Shale, Mt McRae Shale, Mt Sylvia Formation, and parts of the Wittenoom and Jeerinah Formation. With the exception of BIFs, all other units contain zones with varying amounts of sulphides and carbon û æreactive shaleÆ. Reactive shale has a propensity to self-heat and can react with some explosives, resulting in spontaneous explosion. Sulphide rich zones also have the potential to generate acid rock drainage (ARD). Mining reactive shale at the Mt Whaleback mine must be undertaken in a safe, efficient and environmentally responsible manner. Key tasks in the mining process include:100 per cent identification of blastholes that may contain reactive shale; 100 per cent correct loading of blastholes with specified blasting products; 100 per cent of reactive shale mined, hauled and dumped in designated overburden storage areas; 100 per cent containment and treatment of ARD water onsite; and ongoing research into ARD, self-heating and spontaneous combustion. Successful mining of reactive shale requires constant co-ordination between the geology, mine planning, mining and environment departments.

Jan 1, 2002