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By Ravichandar. D., K. B. Nagashanmugam, M. S. Pillai

"Blast furnace performance depends strongly on the coke reactivity index(CRI) and coke strength after reaction (CSR) properties. An innovative and cost-effective method, known as the Salem Box Test, has been developed to prevent the mass production of inferior coke unsuitable for blast furnace use. This method consists of coal carbonization on a micro-scale and involves charging approximately 18 kg of coal blend in a stainless steel box, carbonizing it together with coal cake in the plant coke ovens, and testing the coke produced for CRI and CSR to determine its suitability for blast furnace use. Only coal blends that yield coke with CRI <25% and CSR >64% are permitted for mass production, and other coal blends are either rejected or the blending ratios adjusted in an attempt to upgrade them. The experimental results reveal that, for a given coal blend, the quality of coke produced by the Salem Box Test is comparable with that produced by bulk production, indicating that the test is acceptable as a screening tool for regular use. The present paper describes the methodology and application of Salem Box Test to predict the suitability of coke for blast furnace use at JSW Steel Limited, Salem Works (JSWSL), and illustrates its advantages in adjusting the coal blending ratio to produce superior coke, in detecting coal contamination, and in preventing bulk production of inferior coke."

Jan 1, 2015

By R. Altindag

In rock cutting mechanics, the effects of the rock and coal brittleness on the efficiency of cutting bits are examined by many researchers. There is no universally accepted brittleness concept as a measure of cutting efficiency. The effect of the brittleness on rock cutting has not been completely explained. The aim of this study is to correlate the relationships between Specific Energy (SE) and brittleness concepts. The applicability of various brittleness measurement methods for rock cutting efficiency has been investigated. In this study, the raw data derived from previous experimental studies were used, and the relationships between SE and brittleness concepts were investigated. The two previously used brittleness concepts, which are named as B1 (the ratio of compressive strength to tensile strength) and B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), and a new introduced brittleness concept named B3 (the area under line in relation to compressive strength and tensile strength) were evaluated in this study. The relations among these brittleness concepts for rock cutting efficiency were established using regression analysis. There is no correlation found between the SE values and the brittleness of B1and B2values. But, the SE is strongly correlated with the brittleness of B3. It was seen that the suggested brittleness of B3concept could be used as an indicator in rock cutting efficiency analysis.

Jan 1, 2003

By David Evans, David Barnes, Robert Raponi

"The Williams Mine processes, on average, 6,450 t/d of gold bearing ore using two parallel grinding circuits, leaching and C.1.P., carbon stripping, electrowinning and refining. At present, each grinding circuit consists of a SAG mill in closed circuit with a spiral classifier and a ball mill in closed circuit with two stages of cyclones.Since grinding has always constituted the largest portion of milling costs, the Williams Mine has been proactive in trying to reduce such costs through innovative changes. One project under consideration is the replacement of one spiral classifier by a vibrating screen.This paper discusses the testwork performed to evaluate the replacement of one spiral classifier by a vibrating screen, and the preliminary engineering performed to date.IntroductionThe Williams Mine, located in northwestern Ontario, approximately 40 kilometres east of Marathon, is part of the Hernia gold camp. The mine is operated by the Williams Operating Corporation and is owned by the Teck Corporation and Homestake Canada Incorporated. Operation of the mine started in October 1985 at a rate of 3,000 t/d. After a mill expansion in August 1988, throughput increased to 6,000 t/d. Production has increased steadily since the mill expansion and in 1995, an average of 6,450 t/d of ore was processed at a recovery of 95.1 %."

Jan 1, 1997

By K. Yathavan

Fracturing of rock at low stress levels can be a source of unexpected problems in rock engineering: • the resulting instability can be a safety hazard; • in very brittle rocks it may be associated with violent failure of the rock and strainbursting (rockbursting); • it usually leads to an unexpected requirement for rock support, with time and cost implications; • in rock boring projects, it may result in fracture of the rock ahead of the bored face and in the walls of the bore behind the face. This may lead to cutter head vibration, increased cutter wear and consequently decreased performance and increased costs. Examples of situations in which fracturing of rock at very low stress levels has been observed will be described. This will include details or estimates of the in situ stress magnitudes and the rock strengths involved. La brisure de roche sous faibles contraintes peut être l’origine de problèmes inattendus en génie minier : • L’instabilité résultante peut devenir un danger • Elle peut provoquer des éclatements violents des roches fragiles • Elle nécessite souvent une infrastructure de soutien de la roche, ayant des implications sur les coûts et les délais • Les forages de la roche peuvent provoquer une brisure de celle-ci au niveau de la surface forée mais ainsi à l’intérieur de la roche, causant parfois des vibrations et une fatigue de la tête de forage, induisant une baisse de performance et un accroissement des coûts. Nous avons décrit ci-après des exemples de situations de brisure de roche sous faibles contraintes. Cette description comprend des détails ou des estimations des forces et des contraintes impliquées. Cette étude représente la base du travail de recherche effectué sur le phénomène. ißbildung im Gestein unter niedrigen Stressbedingung kann eine mögliche Ursache sein für unerwartet auftretende Probleme in der Felsmechaniklehre: • Die resultierende Instabilität stellt ein mögliches Sicherheitsrisiko dar; • In sehr sprödem Gestein kann es verbunden sein mit einem plötzlichen und gewaltsamen Zerfall des Gesteins; • In den meisten Fällen ist eine nicht eingeplante Gesteinsabstützung erforderlich, und damit ein Zeit- und Kostenaufwand verbunden; • Bei Bohrungsprojekten kann es dazu führen, daß es während des Bohrvorganges zu einer Rißbildung im Gestein hinter und vor der gebohrten Felswand kommt. Dies kann Bohrkopfvibrationen, eine erhöhte Bohrkopfabnutzung und folglich eine Bohrleistungssenkung, sowie Kostenerhöhung zur Folge haben. Das Phenomen von Gesteinsrißbildung unter niedrigen Stressbedingung wird anhand von einigen dokumentierten Beispielen erörtert. Diese beinhalten zudem Details oder Schätzungen bezüglich der Stärke des in situ Stressfeldes, sowie der gegebenen Gesteinsstärken. Die mit diesem Beitrag dokumentierten Ergebnisse formen eine Grundlage zur weiteren Forschung dieses Phenomens.

Jan 1, 2003

By F F. Pitard

The optimisation of a metallurgical plant requires two kinds of sampling systems. The first provides samples to follow process changes, so in due time actions to maintain key parameters within pre-established specifications can be applied. The second provides composite samples at the end of a working shift to demonstrate that valuable constituents sent to the plant went to either a final concentrate or to the tailings in a logical, expected proportion. Contrary to what many experts may claim, these two kinds of sampling requirements are incompatible and cannot be fulfilled using the same sampling systems; this is because the required samples have completely different objectives. A process control sample is an instantaneous sample with increments taken at short intervals, and the objective is to know where the process is at any given time. Excellent accuracy is not a must, however good precision is recommended since a possible process correction may need to be made. Online analysers fed with in-stream stationary cutters or other kinds of in-stream or by-stream probes can do well for such a mission. A composite sample for metallurgical accounting with increments collected over a long period of time, for which excellent accuracy and good precision are both required, must be generated by sophisticated and extremely well-maintained cross-stream sampling stations. The use of process control sampling systems to achieve good metallurgical accounting has been promoted by several manufacturers of sampling equipment around the world; it is a grave mistake that is misleading top management and a practice that should be scrutinised and preferably eliminated. Furthermore, bias tests used to prove otherwise are often based on insufficient data to draw valid conclusions; a guideline is provided.CITATION:Pitard, F F, 2014. Sampling systems for process control and metallurgical accounting, in Proceedings Sampling 2014 , pp 25–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By H. Fayed

Two-phase (water and air) flow in a self aerated WEMCO flotation machine has been investigated using computational fluid dynamics (CFD). A 0.8 m3 model is considered. The flow is modeled by Euler-Euler approach, and transport equations are solved using a commercial software ANSYS-CFX5 [1]. Because of the lack of circumferential periodicity in this machine, the entire machine is modeled and unsteady simulations are conducted in the whole volume of the bulb. Uniform bubble diameter is specified, and the effects of bubble diameter are determined by conducting simulations for three diameters of 0.5, 0.7, and 1.0 mm. The unsteady air flow rate through the machine is predicted as an outcome of the simulations. Air volume fraction contours and velocity field in different parts of the machine are presented and discussed.

Jan 1, 2012

The Golden Cross Mine will be the first underground gold mine in New Zealand to operate since 1952. The development plans, along with the conditions and circumstances presently found in the now ongoing mine development, will be discussed as well as a brief review of planned stoping activity and stoping results to date.

Jan 1, 1991

By B. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformations. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, time-lapse point clouds of mine workings. In order to determine sloughage volumes and locations, a total of 11 laser scans were performed 41 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds.

Feb 27, 2013

By D F. S Natusch, R J. Hooper

Recent lignite investigations indicate their potential as a strategic long-term fuel resource. This potential however would be determined not only by lignite quantity and quality, but also by economic, physical and social resources required to support it. The following discussion uses the example of a typical lignite mining operation to review the major resource requirements. While recognising that the implications of supplying those resources may be as important as their actual existence, this paper has purposely omitted such discussion as this will be one of the main target areas for the next phase of investigations.

Jan 1, 1983

By H. J. Handewith

This paper explores the state-of-the-art of mechanical rock drilling and boring methods in use in the year 2000. It covers the basic mechanisms of cutting tool design and outlines the current understanding of related rock fracture methods. It provides suggestions for future research needs and discusses the mining and construction markets that are driving these needs.

Jan 1, 2001

Federal regulations require the use of methane monitors on all mining machines. All machine-mounted methane monitors currently used in underground coal mines rely on catalytic heat of combustion sensors. As a comparison, although not currently approved for use on underground mining equipment, instruments with infrared sensors are evaluated in this study. Potential advantages of using infrared sensors include faster response time, long-term stability, and reduced maintenance needs. Tests conducted in the laboratory and at a full-scale model mine compare the performance of catalytic heat of combustion and infrared sensors operating under test conditions designed to simulate airflow conditions underground.

Jan 1, 2009

By A. Nieto

A dump edge and vehicle proximity warning system is being developed at the Colorado School of Mines using GPS and wireless local area networks to improve the safety of off-highway trucks in open pit mines. After two years of research, software development, and testing in the laboratory, field tests are currently being carried out at operating limestone quarries and open pit mining operations to evaluate the effectiveness of the system under rugged operating conditions. This paper describes the progress made on this NIOSH-funded project and discuss, tests carried out recently, at the Morenci open pit copper mine in Arizona.

Jan 1, 2002

By Masaki Kitazume, Yoshiaki Kikuchi

"Abstract Pile foundation is one of fundamental techniques to improve the bearing capacity and settlement characteristics of superstructures. Wide varieties of piles having various shape, size and material were developed and have been applied to a lot of construction projects throughout the world. The deep mixing method, an in-situ admixture stabilization method, was developed in 1970s in Japan and the European countries, and has been frequently applied to many construction projects for various improvement purposes such as increasing bearing capacity and horizontal resistance, reducing ground settlement, preventing liquefaction and so on. The design methods, execution procedure and quality control and assurance (QC/QA) of the method are standardized or specified in many countries. These standards, specification and/or technical manual have been a remarkable contribution to spread the techniques throughout the world. The QC/QA is one of the major concerns for clients and engineers who have poor or no experience of the technologies. In order to assure the high quality of deep mixing work in the global market, it is necessary to establish the concept of QC/QA and correlate the output of different procedures. Upon the request by the organizing committee of the DFI-EFFC International Conference on Piling & Deep Foundations, the authors conducted survey of the specifications and standards on the piling and deep mixing technologies in Asian countries. In this manuscript, the results of survey are briefly introduced by comparing these specifications and standards.IntroductionThe pile foundation is one of fundamental techniques to improve the bearing capacity and settlement characteristics of superstructures. Wide varieties of piles having various shape, size and material were developed and have been applied to a lot of construction projects throughout the world. The design method, execution procedure and quality control and assurance of pile foundations are standardized in many countries based on the accumulate research results, laboratory and field experiences. In Japan, steel pipe piles are mainly constructed by hammer driven in port construction. On the other hand, precast pre-stressed concrete piles or cast-in-place piles are mainly used in on land construction. When precast pre-stressed concrete piles are constructed, piles are usually set by inner excavation method because of preventing noise and vibration problems. More than 50 years ago, noise and vibration problems had not been serious problem in Japan, but around 50 years ago, they became serious and now less noise and vibration construction methods are used for pile construction on land in Japan. In Asian countries, though piles used for construction have a lot of variety, precast pre-stressed piles are commonly used. In this report, execution controls of construction methods of steel pipe piles and precast concrete piles are mainly considered."

Jan 1, 2014

By P. K. Narasimharaghavan

The major threat to the sustainability of Aluminium Industry is its significant contribution to global warming by way of generation of non eco-friendly gases during its production cycle from Bauxite to the finished product. Though reduction measures are taken in control and effective recovery of values from pot room gases, efforts in use of environment friendly additives in the final products production line is warranted. In this line, the present paper describes our efforts in the use of a new generation refining flux which apart from helping in effective removal of alkali metals, reduction in inclusions and ensure a better metal cleanliness shall also aide in reduction of obnoxious gases generated during the metal refining process prior to casting. The aim of the current work was to reconcile the practical results with the old generation fluxes used. Further improvements to bring in a better metal cleanliness will also be discussed.

Jan 1, 2010

By Leslie F. Sawatsky

Failure of drainage works is one of the principal threats to the sustainability of mine closure facilities but the risk can largely be remedied by appropriate design of mine closure drainage facilities. The feasibility of sustainable mine closure facilities that avoid failure of drainage systems needs to be established during the early stages of mine planning, before mine disturbances make sustainable closure uneconomical. Experience in mine development shows there is often enough latitude in mine plan development to incorporate measures with neutral economic consequence and positive environmental benefit. Project managers need to resist the temptation to develop mine plans and closure drainage plans independently. Integrated mine planning with effective inputs by environmental specialists and drainage designers may affect the overall mine configuration, footprint and schedule. Key issues pertain to the end pit location, waste dump configurations, pit infill elevations, fluid impoundments, diversion channel routing and preservation of flows to receiving waters. Guidelines with illustrations of suitable practices are presented to assist mine planners.

May 1, 2004

By V. I. Lakshmanan, D. A. Mackie

"1. INTRODUCTIONIn the past two decades, low-grade gold and silver ore bodies in the United States have been exploited by heap leaching, primarily with sodium cyanide solutions. This method has proven to be a viable alternative to conventional milling due to its low capital and operating costs. Successes have been made, particularly in Nevada, where ores are well oxidized and the climate is conducive to this method. in recent years, heap leaching has been tried in northern latitudes with some success, however, in using this method, operators face more severe limitations than do their neighbours to the south.This paper evaluates the limitations of heap leaching with particular emphasis on northern climates and introduces an alternative method to recover precious metal values in a continuous vat. This proprietory technology, known as the Mackie Vat Leaching Jig, shows promise, with improved gold recovery and potential to operate in cold climates.2. WHAT ARE THE LIMITATIONS TO HEAP LEACHING?Heap leaching of non-refractory ores is subject to the following limitations:1. Minimum amount of free gold and nuggets in the ore.?. Minerology of the ore--accessibility of gold to lixiviant.3. Minimum particle size and size distribution of crushed product to allow percolation of lixiviant through the heap.4. Minimum amount of clays or clay-like slimes that can cause coating of ore particles and channelling of lixiviant.5. Minimum strength of ore particles or agglomerations to allow economic height of heaps to be built.6. Amount and suitability of real estate.7. Amount and type of precipitation.8. Ambient temperatures.9. Possible poorer lixiviant diffusion.10. Possible lower oxygen content in dissolved cyanide solution with higher heaps, particularly with ice and snow cover."

Jan 1, 1989

By R. Grimard, M. Gamache, L. -P. Bigras, P. Cohen

This paper describes a real-time fleet management system for an undergroun mine. Dispatching, routing and scheduling are handled simultaneously, taking into account the mine status, operational constraints and vehicle location information. Each assignment decision takes into account the traffic on the road segments of the mine network, whether road segments are bi-directional or uni-directional, and ensures that each LHD (load-haul-dump) vehicle arrives at loading and dumping points with the correct orientation. Such a system can be used either as a simulation tool for strategic planning or as a real-time managing and optimizing system for operations. In the simulation mode, the system can accurately estimate the impact on productivity of decisions such as the development of waiting areas (bays, sidings), or the addition (elimination) of vehicles to the fleet in operation. When used for real-time dispatching, routing and scheduling of vehicles, the system can optimize production with respect to various assignment criteria such as cycle-time minimization or deviation from a target production plan.

Jan 1, 2004

By E. P. Abrahamson II

The effect of transition elements which form binary solid solution upon the recrystallization temperature of zirconium has been investigated. All additions raised the recrystallization temperature. A correlation is obtained between the logarithm of the rate of change of recrystallization temperature with atomic percent solute and the free atom ground state electron configuration of the solute element. ThE work of Abrahamson, et al., on dilute binary solid-solution alloys indicated a correlation between the free-atom ground state electron configuration of the solute and either the brittle-ductile transition or recrystallization temperature. These studies were carried out on bcc base materials. The implication is that the outer s and d electrons of the solute are the prime determinant of the absolute rate of change of recrystallization or transition temperature. Furthermore, the limit of linearity has been shown to be a function of solute electron configuration for recrystallization in iron and vanadium. To date no Complete systematic recrystallization study of dilute binary zirconium base alloys has been made. It is the purpose of this study to note whether the change in solvent structure from bcc to hcp will influence the correlation. It was also desired to learn more of the role of the electron configuration of the solvent on recrystallization temperature. PROCEDURE All alloys were made using 99.87 pct Zr with 0.01 Cr, 0.04 Fe, 0.006 Hf, 0.003 Mg, 0.003 Mn, 0.003 N, and 0.080 0 (132 BHN). The solute elements were 99.9 pct pure. According to the published binary phase diagrams6 and metallographic examinations at X750, all alloys used were solid solutions. The alloys were arc melted and remelted six times in the form of cubic 200-g buttons under an argon atmosphere. They were then hot pressed at 950°C to 0.450 in., upset pressed to 0.350 in., and annealed at 800°C for 1 hr. The specimens were then Blanchard ground to 0.250 in., removing 0.050 in. from each side. The grain size of the material at this stage was found to be 8000 100 grains per sq mm. The specimens were then cold rolled to 0.130 in. and cold pressed to 0.125 in., yielding 50 1 pct cold work. All alloys were then chemically analyzed for the principal addition. The interstitial contents remained at the values of the starting material when checked on random alloy specimens. The rolled sheet was cut into 6.75 by 0.25-in. lengths and heat treated in a gradient furnace for 1 hr. The gradient was 250o to 900°C over the 6-in. length, recorded continuously by six thermocouples resting on each specimen. Control was 3oC, accomplished at the hot end. The recrystallization temperature was determined metallographically using polarized light. The criterion chosen was the point on the specimen showing the first recrystallized grain at a constant magnification, X200. Specimens were repeated, and the agreement was found to be 3°C. RESULTS Three different pure zirconium specimens were tested, and the recrystallization temperature was

Jan 1, 1962

By Dave Capstick, Ken Garner, Jim Porter

Technologies and systems used in the management of energy consumption in the mining and metal processing industry are well understood and documented from the supply side of the business. It is our contention that in many instances, through a more complete understanding of the demand side of the business, based on the detail of the operations plan, will provide greater lead time in terms of the design, implementation and utilisation of power supply infrastructure. Thus, optimal management of demand in a proactive manner, based on production requirements, will ensure both security of supply as well as continuity of operations. This paper describes the technology and methodology that is being developed to enable the above statement to be achieved. We use a case study to demonstrate the ability of the tools and methodology and conclude by outlining the business benefits achievable as well as the future developments emanating from this initiative.

Jan 1, 2005

Tried, Tested and Proven - 300 m3 Flotation Cells in Operation

Sep 13, 2010