Search Documents

By B Mobilio, M Secheny, J Rachocki, G B. Sharrock, A Jäger, J L. Lett, I Brunton, G W. Capes

Establishment of the Cadia East Panel Cave Stage One (PC1S1) commenced with the firing of the first bell in early 2011. Production began with the completion of the undercut in May 2014. PC1S1 used a post-undercut composed of 114 drawbells covering a footprint area of 73 438 m². The extraction level is located at a depth of 1200 m below the surface and is based on a 32 × 20 m El Teniente layout. Cave establishment required the construction of multiple conveyor drifts, a large-capacity jaw-gyratory crusher and ancillary ventilation and pumping infrastructure. Preconditioning via hydraulic fracturing and blasting was implemented at various locations of the cave block height. This paper presents an overview of the key learnings from the commencement of undercutting to surface breakthrough, including rock mass classification and modelling, stress measurements, preconditioning, numerical modelling and cave monitoring.CITATION:Lett, J L, Brunton, I, Capes, G W, Jäger, A, Mobilio, B, Rachocki, J, Sharrock, G B and Secheny, M, 2016. Undercutting to surface breakthrough – Cadia East panel cave (stage 1), in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 65–82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By C. D. King

DURING the 30-year period spanned by these annual Howe Memorial presentations, many lecturers could proudly claim a kinship either as a student or an associate of the man whose memory we honor. Although it has been my good fortune to have attended many of these annual lectures, it was not my privilege to have known Henry Marion Howe personally. However, his great repute as teacher and scientist was known to all undergraduates of my day and the later years have enhanced my appreciation of his wisdom and foresight. Those who knew him well have said he derived particular pleasure from speculations on the future world of metallurgy. For this reason, I feel that perhaps he would not be unsympathetic to a lecture in his honor which departs from the highly instructive scientific presentations made in the past by so many able Howe Memorial lecturers, and which is concerned more with the practical phases of various steelmak-ing processes and some speculations on their future form and relative importance. The word "revolutionary" is frequently applied to each seemingly important improvement in the production of steel ingots, but in retrospect these changes, impressive as they appear at the time, are merely steps of progress. In the hundred years from the inception of tonnage steelmaking, only three processes can be truly classified as revolutionary. They are the pneumatic process, known in this country as the bessemer process; the reverberatory method called the open hearth process; and, the electric furnace process. There have been many variations and combinations of the three fundamental methods, but they remain truly the only revolutionary methods in steelmaking since its early history. Everything else has been evolutionary, in effect. doing the same things that we have done in the past but doing them better, correcting our errors through experience, and slowly but inevitably reaching a higher state of accomplishment. It has often been said that coming events cast their shadows before, and the production of steel ingots is no exception. As a result of the unrelenting demands of World War I1 and the years that followed, truly impressive progress has been made in steel ingot production. The incessant pressure for immediate results during this period required the employment of initiative and daring, as in few past decades, and many developments were brought to fruition. Of equal importance is the possible effect on future steelmaking methods of the many ideas initiated but still in formative stages. Fig. 1 portrays ingot production in the United States by the three fundamental processes over a period of 75 years and is interesting because it poses some questions as to future trends. The early ascendancy of the bessemer, its replacement in importance by the open hearth process, the amazing growth of the latter, and the recent challenge of the electric furnace are evident from the chart. Management is fully aware of these changes, but is even more interested in the future trends. Our concepts of the relative importance of the more recent developments and their possible effect on future processes may perhaps be best exemplified by a specific, hypothetical problem. Let us assume management is contemplating a new ingot producing plant with an output of 100,000 net tons per month, located in an area where some purchased scrap may be obtained but where by far the largest component will be own-produced blast furnace iron. Management requires a process or combination of processes which will yield highly uniform quality characteristics in the ingot form, and represent the soundest selection in investment and operating cost. Under these conditions, the obvious selection for the past four decades has been the open hearth process but, in view of more recent developments, management may believe that it is no longer permissible to disregard other possibilities with impunity. Accordingly, to be assured of the best possible selection, they request that you review not only the possibilities of utilizing the conventional open hearth, duplex, bessemer, and electric furnace methods, but also the more recent developments, such as the turbo-hearth, the Linz-Donawitz method, the Perrin modifications, and other possibilities. With this background, one might then appraise the relative importance of these methods to meet a specific need, and concurrently speculate on the forms that future ingot processes will assume and the relative importance of these processes.

Jan 1, 1955

By Clarence Zener

The heat-treatment of steels will not pass from the stage of an art into that of a science until the mechanism of the phase transformations associated therewith is thoroughly understood. Such an understanding will involve two distinct types of inquiry: (I) the direction of the transformation, (2) the speed of the transformation. The first type of inquiry, which involves only the equilibrium relations between the various phases in steel, is the subject of the present and of a succeeding article; the second type, which involves the kinetics of transformations, will be the subject of a later article. In order that a theory of equilibrium relations may give useful information, certain experimental data must be put into the theory. It is customary for these data to be of a thermal nature. In the system discussed herein—steel—such thermal data are very scarce. In medium-alloy steels another type of data might possibly be used. In these steels the concentration of solute is so low that it may be possible to use the approximation of dilute solutions, an approximation that leads to linear relationships. The unknown functions, or constants, may then be determined in some cases from the binary iron-alloy system and in other cases from the ternary iron-carbon-alloy system. From the functions, or constants, so determined may then be computed the equilibrium relations in more complex medium-alloy steels. In the present article this second approach is used, the necessary experimental data 'being obtained from the simple binary and ternary equilibrium diagrams. Fundamental Equations In this article are derived the equilibrium relations between the gamma, alpha and cementite phases. In these three phases all important alloying elements except carbon form substitutional solutions, each alloying atom occupying a potential site for an iron atom. Carbon, on the other hand, forms an interstitial solution. In the face-centered cubic gamma phase, the interstitial positions are at the center of the unit cube and at the centers of the cube edges. There are therefore four interstitial positions per unit cell, or one per iron atom. In the body-centered cubic alpha phase, the interstitial positions are probably at the face centers, and also at the centers of the edges, which are crystallographically equivalent to the face centers. There are therefore six interstitial positions per unit cube, or three per iron atom. In cementite, (Fe, Alloy)3C, the carbon atoms may. be regarded as filling all the lattice positions of a given type. The introduction of the fundamental the of equilibrium has presented the author with a quandary. These equations are formally so similar to other equations that have been derived1,2 for related systems that they may appear to some readers

Jan 1, 1947

By Alfred E. Hunt

Tars paper is suggested by the appointment on the part of the American Societies of Mechanical and of Civil Engineers of committees upon the subjects of " Standard Tests and Methods of Testing," and " Uniform Methods of Tests of Material used in Metallic Structures," respectively, and by a study of the report of one of these committees, and other papers. Moreover, the writer has had frequent occasion to hear the complahts of tnanufacturers who furnish structural material subject to specifications, that in the tests prescribed, the number of tests required, and the methods of making

Jan 1, 1892

The February General Meeting of the Institute was held in Kelvin House, Johannesburg, on 19th February, 1969 at 4.30 p.m. Mr R. C. J. Goode (President) was in the Chair. There were also present forty-six Members, including Messrs H. E. Cross, A. R. C. Fowler, P. Lambooy, D. G. Maxwell, Dr J. T. McIntyre, Messrs J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), Messrs G. Abdinor, H. F. Allan, R. E. Barnes, M. M. Bayley, J. K. Boyd, R. R. M. Cousens, R. E. F. Cowley, D. Savile Davis, H. J. Davisson, C. T. Fenton, J. Fergusson, J. Fritz, M. L. Fitzgerald, J. M. Gosnell, J. C. Hall, S. A. Hancox, D. M. Jamieson, Dr D. G. Krige, Messrs J. E. V. Leeuwen, A. Louw, C. F. Louw, B. H. L. Leach, R. B. MacGillivray, C. S. McPhail, E. Margo, G. G. Nicolson, E. Pavitt, M. P. Pearse, F. O. Read, Dr M. D. G. Salamon, Dr H. S. Sichel, Messrs D. Storrar, S. G. Taussig, A. H. Taute, E. B. Viljoen and P. A. von Wielligh. Sixteen Associate Members, including Messrs S. T. Baron, W. M. Fitzpatrick, M. R. Fuller-Good, P. R. Garcia, H. G. Gericke, P. D. Hatfield, R. Hemp, G. S. Lee, Miss V. E. Marting, Messrs A. H. Munro, R. C. Power, O. F. Rheeder, G. C. Thompson and N. Zolezzi. Two Graduates, Messrs D. Bosley and J. C. Sutherland. Three Affiliates, Messrs R. K. Briggs, A. B. Cook and G. M. Thain. One Student, Mr P. W. Henrard. Twenty-three Visitors, including Messrs N. J. W. Bell, R. G. Bushell, A. Bryan, J. F. Cillie, C. M. de Beer, Dr F. H. Deist, Messrs D. S. Drake, P. G. du Plessis, R. W. Hodgson, D. M. Hawkins, S. C. H. Kearns, M. D. Labuschagne, L. Munro,R. Murchison and L. Robinson. Secretary, Mr D. C. Visser. Total present: Ninety-two. OBITUARIES The President: "It is my sad duty to announce the death of the following members of the Institute. Edward Frank Jud Bulman, Life Member, who joined the Institute in 1931 and passed away on 7th November, 1968. Elmar Fenton Chapin, Member, who joined the Institute in 1941 and passed away on 17th November, 1968. Solly Rabinowitz Rabson, Member, who joined the Institute in 1944 and passed away on 13th February, 1969. Mr. Rabson was the holder of two certificates of merit for papers presented to the Institute.

This paper reviews the commissioning and operation of the process plant at Tolukuma over the past 18 months. The plant treats a high-grade gold and silver ore through a SAG mill followed by a conventional carbon-in- leach (CIL) circuit. Gold is

Jan 1, 1997

By T. H. Jeffers

Significant amounts of cobalt are present in readily accessible spent copper leach solutions. The Bureau of Mines investigated the feasibility of extracting cobalt from these solutions in a multiple-compartment ion-exchange (MCIX) column. The effects of aqueous flow rate, resin flow rate, column height, and compartment height on cobalt extraction were determined. Cobalt extractions of 92 pct or higher were achieved at solution flow rates of up to 5.5 gpm/ft of column cross-sectional area and an aqueous-to-resin flow ratio of 40:1. Overall cobalt extraction increased as the column height increased, but cobalt extraction per unit of length was more efficient in 8-and 12-ftco1umns than in an 18-ft column. Solvent extraction procedures were utilized to purify and concentrate the MCIX column eluates and produce a cobalt sulfate solution containing 70 to 80 giL Co. Metallic cathodes containing over 99 pct Co were e1ectrowon from this solution. Zinc, nickel, and copper byproducts were also recovered during processing of the ion-exchange eluates. Estimated total capital cost for a commercial-scale 10,000 gpm of a spent leach solution containing 26 million. With credits for zinc, nickel, and copper estimated net operating cost was $9.36/lb Co.

Jan 1, 1987

Jan 1, 1953

By R. P. Carreker, J. G. Leschen, J. H. Hollomon

THE external appearance of a crystal which has undergone plastic flow suggests that adjacent blocks of the crystal have glided bodily past one another along the slip planes. However, the great discrepancy between the shear stresses calculated to effect such a movement and those actually observed has for many years stimulated searches for more satisfactory interpretations of the slip process. Appreciable success in these efforts has been realized by assuming the presence in the crystal of various sorts of imperfections and by considering the consequences of the presence of these flaws when stress is externally applied, The theory that has received the most attention recently-that of dislocations-postulates the occurrence of small, mobile imperfections or dislocations which move through the crystal along the slip direction, each dislocation being attended by a local shear displacement of one interatomic distance. Thus only that portion of the crystal through which the dislocation has passed may be said to have slipped, Since each dislocation produces a displacement of only one interatomic distance, an avalanche or train of many dislocations would be necessary to account for the observed displacements of several hundred or thousand interatomic distances. The salient point of the theory of dislocations is the concept that a slip band does not suddenly appear in its entirety. On the contrary, it grows progressively across the slip plane as the individual dislocations successively appear and advance in a train through the crystal. However, the concept of growth is not intrinsic only to the theory of dislocations, since atomistic mechanisms other than that postulated by the dislocation theory can quite probably also describe the growth of a slip band. For instance, a slip band might resemble a disc-like interface that appeared and then grew continuously from a small size, producing a displacement that increased with the size of the disc, Whatever the precise mechanism, the concept of growth is in itself consistent both with -the observed low values of critical shear stress and with the experimental observation that slip bands. frequently do not traverse the entire crystal. The likelihood that slip bands grow implies that they must first be nucleated and that the initiation of slip can therefore be analyzed in terms of the general concepts of nucleation. Indeed, this suggestion was advanced1 several years ago, but the matter does not appear to have been further pursued. Recent advances in the theory of nucleations2,3,4 have encouraged such a treatment of the slip process. As will presently be demonstrated, this approach to the problem not only accounts successfully for the incubation periods that have been observed5,6 to precede slip but also predicts certain transient effects in the deformation process, The existence of these transients apparently has not hitherto

Jan 1, 1948

By Syd S. Peng

In the past few years, the numbers of underground coal mines in this country using longwa11 mining method have been dramatically increased. In the latest count there are approximately 90 10ngwa11 faces amounting roughly 8% of the total underground production. Meanwhile, shortwall mining adapting longwa11 powered supports to 'coal mining and handling systems in room and pillar mining is also gaining importance in the Appalachian coal field. Although there are only 7 operating shortwall faces so far, indications are that it will be increasing steadily. Modern longwall faces are highly mechanized and productive. One of these key elements that contribute to the success of modern longwall mining is self-advanced powered supports. There are several types of powered supports. Frame type is two sets of one to four hydraulic legs supporting beam-type roof canopy and floor base. However, chock type is more popular and connected to broad roof and base structure. Shield supports were introduced recently but proved to be highly successful (1). A shield support consists of two hydraulic jacks mounted between a base plate and a gob shield. The base plate is hinged to gob shield which is in turn hinged to roof canopy.

Jan 1, 1977

By Paul C. Schmall, Arthur B. Corwin, Derek Maishman

Ground freezing occupies a unique and important niche in underground construction, fulfilling a geotechnical need that is difficult, or sometimes impossible, to fulfill through other groundwater control and excavation support methods. Where complete groundwater cut-off and in-built ground support are required, and deep excavation is planned or the work occurs in difficult or disturbed ground, ground freezing offers the assurance critical to safe and timely construction. Compared with other groundwater cut-off or excavation support methods, a frozen wall is easily connected to underlying bedrock and will also adhere to adjoining subsurface installations or obstructions, if necessary, to provide a composite cutoff structure. Ground freezing is effective in all soil and ground conditions and has been used for emergency situations in disturbed, displaced or loose ground, where detailed soil characterization could not practically be performed.

Jan 1, 2005

By V. S. Rood

Typical System of Workings THE general system of workings at the Utah-Apex is similar to that found in many of the western metalliferous mines. There is a vertical three-compartment shaft extending to the surface, from which the various levels have been driven to the orebodies. The 1000-ft. (305-m.) level, about ¾ mile long, was driven as a haulage and drain adit. Geology The formation is a flat north-dipping series of alternating limestone and quartzite beds. Extensive north-south faulting and-fissuring have taken place, resulting in the formation of large replacement orebodies in the crushed zones in the limestone. The orebodies are irregular in shape and size, but follow closely the trend of the mineralizing fissures. The ore consists of galena, pyrite, sphalerite and small values in silver and gold. Large masses of non-commercial pyrite are frequently found in or adjacent' to the orebodies, and more or less pyrite is found for some distance in the walls of the orebodies. Lenticular bodies of a black pyritic shale also occur in the zones where extensive faulting has taken place.

Jan 6, 1918

By Anthony L. Reynolds, Clifford J. Wren

"The adoption of a significant pile testing regime, the use of Eurocode 7 as the design standard, the development of lean construction techniques, and lateral thinking in overcoming some considerable construction challenges allowed Stent Foundations to construct the foundations for the new Wembley Stadium, London, on time and within budget. In addition to the piling works for the main stadium, and after significant design development, a large number of extra piles were required to raise the new iconic roof Arch to its final position some 133 metres above the ground. A 1,400m long contiguous bored pile wall was also constructed to allow for excavation and formation of the new pitch. INTRODUCTIONHjstorjcal lntrodyctionWembley Stadium is the 'home of English football'. As long ago as the 1880's, Wembley Park leisure grounds had football pitches and running tracks.In 1918 the British Government began planning a British Empire Exhibition with a stadium as its centrepiece. The Exhibition area covered 219 acres and the area on which a former abandoned tower called Watkins Folly had stood was chosen as the site for the new stadium (http://www.wembleystadium.com).The Empire Stadium, as it was originally known, was designed by architects Sir John Simpson and Maxwell Ayerton and the engineer Sir Owen Williams. It took just 300 days to complete at a cost of £750,000 ($1.4m), and was built using 25,000 tons of ferro concrete, 1,000 tons of steel, and over half a million rivets.The Empire Exhibition was a remarkable event, containing fountains, lakes, gardens, and many pavilions, each representing the architectural style of the countries exhibiting. It was opened on 23rd April 1924 and the final attendance was over 27 million, with 4.5 million admissions to the Empire Stadium alone."

Jan 1, 2005

GROWTH of the United States to industrial supremacy in the world is mainly because of the rapid exploitation of natural resources. The easily found high grade mineral resources have been depleted and attention has turned to low-grade ores. Progress has been made from the comparatively crude mining and milling techniques, which sufficed for the rich deposits, to more complex technology for exploiting low-grade ores. In spite of this progress the defense program is pointing up the fact that the mining industry is caught short on ability to produce the needed mineral raw materials. The mining industry is digging itself out of business here in the United States.

Jan 5, 1951

By John W. Rushton

THE PLANNED MAINTENANCE PROGRAM All concentrators should start with a planned maintenance program from day one. Every- body thinks they have a program in place before start-up, but in reality, most have only a fraction of what is needed to avoid the "Post Start-up Disaster" (PSD) - two years for start-up is not that uncommon. An effective program has all of the following: (1) Good people. (2) Area Maintenance. (3) Good PM Checklists. (4) Daily Work Schedules. (5) Written Work Orders. (6) Equipment Histories. (7) Backlog Control. The installation of a workable program takes hard work, talent, and commitment. You have to know what you are doing (hard work will not replace talent). Good People Good people are available in any location if you make the effort. Always check references carefully (both superiors, peers and subordinates). Was the last concentrator they worked at successful? Was it clean? Find out! Success or failure follows people around. I know people who are experts on PSD because they have lived through it three or four times. You need some college trained people with hands-on experience. There are no secrets, you have to make the effort. If you make a mistake in hiring (and you probably will), make the tough decision necessary to rectify it quickly. Area Maintenance Area maintenance refers to organization of supervision such that one person is uniquely accountable for every inch of ground and piece of equipment. Avoid overlapping authority if at all possible. You must have a planner as a staff position. A foreman cannot effectively plan and

Jan 1, 1986

During the last two decades, restrictions on access to land for mineral exploration and development in Australia have intensified. State and Federal legislation relating to Aboriginal land rights, national parks, marine parks, wilderness areas and other conservation areas, the surface rights of farmers in New South Wales and Western Australia, national, State and world heritage, urban developments and acquisition of land by governments for other purposes have all placed limits on mineral exploration and mine development activity. More than 20% of Australia's land area is now either unavailable for mineral exploration or available only under severe constraints. Access to this land is denied at a significant economic cost to the Australian community. There have been few attempts to quantify this cost. More importantly these restrictions have developed on an ad hoc basis promoted by single interest government departments often with little regard for rational land use planning. The mining industry has embraced the community's conservation ethic and accepted that conservation areas should be set aside and that within those areas mineral activity should be restricted. In some cases the restrictions on exploration near areas of outstanding scientific, historical, archeological or scenic importance may amount to an effective prohibition. The industry has vigorously opposed the exclusion of mineral activity in conservation areas on purely emotive grounds, unsupported by scientific evidence and in disregard of land use potential, consideration of multiple use potential or consultation with existing or potential land users likely to be effected.

Jan 1, 1987

By J. B. Nau

A short time ago some interesting experiments concerning a new steel-making process in the open-hearth furnace were made by the writer at the Croton magnetic mine, N. Y.

Jan 1, 1892

The design of a mine should aim to optimise the market value by maximising revenues whilst minimising costs. In open pit mining, the nature of the extraction technique translates this objective into the maximum recovery of reserves while minimising waste extraction subject to technical, economical and safety constraints. Since the introduction by Lerchs and Grossman, in 1965, of a model that is now considered a classic in the area, open pit design has reached a level of maturity and acceptance by industry. These models are being used on a regular basis by designers and planners.This paper proposes a new alternative model for open pit design. It is based on genetic algorithms (GA) and exploits a reduction of the number of decision variables of the more traditional techniques. The novel approach provides more flexibility than traditional models; it can also be extended to consider planning problems that traditional open pit design models are not capable of handling. The algorithm has been designed for two dimensional problems and tested in a simple instance. The results obtained in this simple test are encouraging and are a good supporting argument for the development of a GA model capable of handling three-dimensional (3D) instances. The model presented in this paper is just a first step towards a full GA to solve the pit design problem and it is believed that novel tools like the one presented herein could become great allies in tackling challenging problems in open pit design, an illustration of such a challenging problem is presented and discussed.

Dec 6, 2010

By Tobías Posadas

"El presente texto señala los beneficios que otorgan las leyes 15584 y 16066 en favor de la pequeña minería; así como sugiere las normas reglamentarias para que estos sean aprovechados por el mayor número demineros. En ese sentido gozan del beneficio de canon minero, aquellos que tengan menos de mil hectáreas y produzcan menos de mil toneladas al mes, así como los libera de un pago de sobrecanon, los exonera salarialmente, los libera de los impuestos de registro y reduce del importe de los avisos de denuncios. "

May 1, 1967