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Exploring for deep shallow dipping orebodies can be very expensive and very difficult. Surface exploration is often not an option and obtaining the best location for underground drilling can cause production delays if drilling is carried out from development headings. The Otter/Juan mine has been in production for approximately 34 years. All of the production is now sourced from more than 1000 metres below the surface from an area known as the Edwards Lode. The orebody is shallow dipping and open at depth. Exploration drilling has been performed from decline stockpiles and from hangingwall drill drives. Drilling from footwall positions (eg decline stockpiles) into shallow dipping orebodies can often produce intersections which are unusually thick thus leading to optimistic resource figures. The decision to develop a dedicated hangingwall drilling position can vastly improve the quality of the data used to generate an orebody model. In 1997 a new extension to the Edwards Lode was discovered and named the æFÆ surface. In 1999 a resource calculation was performed using data obtained from drilling that was carried out from decline stockpiles. In 2002 a dedicated drill drive was developed into the hangingwall of the æFÆ surface to obtain better data to verify the previous resource calculation. For this case study obtaining more representative data reduced the resource estimate by 66 per cent. This information was obtained early enough to allow for alteration to the mine plan and without loss of capital.

Jan 1, 2003

By T. W. Watson, D. R. Flynn

,Measurements are reported for the thermal conductivity of four heat-resistant alloys which were measured at the National Bureau of Standards. Data are given for two samples of AISI Type 316 stainless steel covering a combined temperature range from -150° to + 800°C. The thermal conductivities of three samples of AISI Type 347 were measured over the temperature range from -150° to +150C. Thermal conductivity values are given for Carpenter 20 stainless steel from 100" to 800" C. Data are given for Inconel 702, in both the solution-annealed and the age-hardened condition, over the temperature range from -150" to +800C. SINCE 1958 the National Bureau of Standards, at the request of other government agencies or private laboratories, has carried out measurements of the thermal conductivity of a number of metals and alloys. This paper presents available thermal conductivity data obtained in this way on samples of four heat-resistant alloys. The data presented for Carpenter 20* stainless steel are, to the best of our knowledge, the only thermal conductivity values which have been reported for this alloy to date. Although thermal conductivity values for AISI stainless steels 316 and 347 have been reported by previous investigators, the present data are believed to be of particular interest because, for each alloy, the effect on thermal conductivity of small changes in chemical composition can be observed. The data on Inconel 702' are of interest, not only for

Jan 1, 1969

Deposits of manganese oxides and silicates in the Tamworth area were re-examined. The major deposit at Danglemah consists chiefly of rhodonite and the rare silicate tephroite. It is considered that the manganese was deposited with the original sediments, the silicates being formed later during the intense folding and low-grade metamorphism of the enclosing rocks.INTRODUCTIONMany small deposits of manganese oxides and silicates occur along a belt of eastern New South Wales and Queensland.Some fifty occurrences, most of which have been subject to mining activity, were described by Lloyd (1943) and some of this information was summarized by Knight (1947). The ores have been mined on a small scale since 1884. Small supplies of battery grade ore were won from a number of deposits, while larger quantities of metallurgical grade were sold to the steel industry. Maximum production was in 1918, when 6,500 tons were mined.The siliceous nature of many of the ores and their occurrence in the neighbourhood of granite batholiths led earlier investigators to consider the deposits to be of hydrothermal origin, associated with the granite intrusions. The present work questions this viewpoint.In this investigation, three of the chief deposits in the Tamworth area were seen. These were at Danglemah, which is being mined at present, and Mount Jasper and Manganese Mountain, which were mined in the past. The Danglemah mine is the most accessible and yields the best material...

Jan 1, 1962

By C. K. McArthur

THE subject of classification is so broad that this discussion is con-fined to what the author believes is of prime importance in connection with proper grinding and classification. The years passed have witnessed many noteworthy changes in fine grinding and classification, which have been accompanied by a readjust-ment of ore-dressing flowsheets for the preparation of better ground and/or sized products at an expenditure of less. power, steel and main-tenance than formerly. Nowhere in the industry is more being done in the way of experimental work to lower costs than in grinding circuits, because, at best, grinding costs are high. Recent years have indicated that, on the average, finer grinding has a real application. Without careful preparation of the process feed, no operation can be highly efficient or successful. In an earlier paper, the findings of an extensive survey at representa-tive concentrators were presented1. Also, in the year of 1935, a technical discussion was given by Dr. J. V. N. Dorr (Some Notes on Classification Trends in America) before the Chemical, Metallurgical and Mining Society of South Africa. In both papers mentioned, much has been said regarding flowsheets, grinding and classification. The author is very familiar with these papers, having had considerable to do with the actual operation of the flowsheets, as well as large mills and classifiers in the work described. Some data from the second paper have been included in the following discussion.

Jan 1, 1937

By Guy Chevalier

QCM?s pellet plant, located in Port-Cartier, Quebec, produces up to 8.6 million tons of iron ore pellets annually. Four different types are produced: three for blast furnace operations and one for direct reduction furnaces. The paper presents the scientific approach that led to the installation of new process equipment to improve the reducibility of direct reduction pellets (DR pellet). The findings, the equipment selection and some post start-up modifications are presented. This low silica DR pellet is used in Midrex and HyL shaft furnaces. A good DR pellet has to meet strict chemical, physical and metallurgical specifications. An important metallurgical property is its ability to release oxygen when exposed to reducing gases. Considering that the market for DR pellets is expanding and being aware that reducibility is critical for our clients, a program to improve the latter was undertaken. Test work showed that one factor which has a negative effect on reducibility is the proportion of particles larger than 75 microns. Knowing that the best way to reduce the amount of coarse particles was to close our open grinding circuits, we began evaluating the most suitable classification equipment applicable to our process operations. We settled on hydro-classifiers based on their very sharp cut and their low operating costs. In light of the hydro-classifiers performance it was also decided to replace the hydro-cyclones of an already closed circuit.

May 1, 2003

By P. K. Chatterjee

The overall success of many strip coal mining operations depends primarily upon the efficient use of draglines to remove overburden. These machines require enormous capital investment and unless used efficiently the profitability of a venture is adversely affected. It is important that the dragline works continuously and it is imperative that the walking path and other facets of its operation be predetermined exactly so that the desired production rate is achieved with a minimum of non-productive time. Details of dragline operations which are of particular interest are walking path, prediction of best cut and positioning to maximize production, the angle of swing which produces the swiftest operation, optimum fill factor allowable for the type of material and conditions of ground, the maximum depth from which it can excavate and operating level with respect to the elevation of the high wall. The aims of the present paper are: 1. To establish a cut-off point in the cost-depth ratio. 2. Predict the most economic method of stripping in a given area using graphical plots of walking path implemented with information necessary to ensure optimum production. The optimum operating efficiency of the dragline in relation to the terrain and other conditions imposed on its operation will be evaluated. The model is based upon operating data which has been collected from site observations of a large strip coal mining operation in Central Queensland, Australia.

Jan 1, 1977

By P J. A Lever

This paper presents details of CRC MiningÆs work with waterjet assisted blasthole drilling. The objective of this work was to investigate techniques that reduce the cost and increase the productivity of blasthole drilling. The focus is on a technology that uses a high pressure waterjet to assist the conventional rotary rock cutting action of a tricone drill bit. The potential benefits of this technique are increased productivity, reduced drill bit wear and reduced hole deviation and hence improved quality of drilling. This paper describes the results of a laboratory based experimental program comparing conventional tri-cone drilling performance to the proposed waterjet assisted approach. Additionally, work has been completed looking at the more practical issues around the collection and sampling of drill cuttings and water recovery (recycling) when drilling with a waterjet. These studies have demonstrated that waterjet assisted drilling can significantly increase the rate of penetration over conventional rotary drilling. For the best-case experimental result, the relative improvement was over 40 per cent. More importantly, it is a starting point for examining alternative uses of the additional drill productivity obtained from waterjet assisted drilling. For example, increased drill productivity could be used to improve rock fragmentation by drilling a tighter blasthole pattern in the same time period. an existing drill fleet, then the drill fleet size could be reduced, or improved rock fragmentation could be achieved by drilling a tighter blasthole pattern within the same time period.

Jan 1, 2004

By J. A. M. van Liempt

SINCE the discovery, of von Laue, that a crystal forms a natural grating for X-rays, our knowledge of the structure of solids has gone forward with rapid strides. This progress is not only of purely scientific interest, but has also yielded direct technological results. One of the most valuable results is the broadening of our knowledge of the structure of pure metals and alloys. To promote these studies it is often desirable to have at our disposal pieces of metal consisting of one single crystal. As is so often the case in the natural sciences, we obtain the best results by making our earliest experiments on pure, simple materials and avoiding unnecessary complications. The Cryogen Laboratory at Leyden followed this method with much success, because the work was done at such low temperatures that the heat movement of the atoms was almost' absent. Similarly we can simplify the studies of metals by leaving out of consideration the influence of the grain boundaries and the mutual influence of the crystals by using unicrystalline instead of polycrystal-line metal. Methods of making single crystals have been scientifically studied during the past few years. Some methods were already known in the arts, but these have been improved and new methods have been developed. The methods for making metallic single crystals may be divided into the following groups: A. From the liquid state B. From the gaseous state C. Electrolytically D. By recrystallization in the solid state

Jan 1, 1927

HENRY M. HOWE, Bedford Hills, N. T. (communication to the Secretary?).-The authors valuable results as to the effects of the air-hardening temperature on high-speed steel may be summed up thus: Influence of Rising Air-Hardening Temperature on. High-Speed Steel Air-hardening microstructure Cutting Properties temperature S Austenite Grain Free Carbide Grains Boundaries Too low Small or Narrow Maximum Too soft undeveloped Intermediate, Well-developed Intermediate Little or even Best correct none Too high Coarse hide, even with Minimum . Weak, brittle, three-rayed crumbling stars Here the suggestion is that as the air-hardening temperature rises it causes two prominent effects, one helpful and the other harmful, the increase of the former exceeding that; of the latter up to a certain point, at which the steel is most useful, and then in turn being outrun by it. The first is the progressive dissolving of the free carbide in the austenite, increasing the stability of the red-hard state. The second is the progressive coarsening of the grains, and thickening of the intergranular cement, developing at last into spandril-like three-rayed stars of the 1,288° specimen. (2,350° F.) of Plate D, thus giving clear proof of incipient fusion, that is of crossing the solidus. This causes intergranular weakness. The individual grains may have great red-hardness, but they do not cohere. They approach the condition of a bag of emery grains.

Jan 6, 1917

By Samuel Sigman, Martin M. Cooper

A basic ingredient for rapid tunnel excavation is material handling. In construction of tunnel projects in urban areas material handling requires additional input to maximize performance. Urban projects share the same problems experienced in all tunnel construction and they must be dealt with. Howeve.., Urban constraints add a larger dimension. APPLICATION ENGINEERING A MUST A word of caution. To achieve increasing speed of excavation in tunnels whether in Urban areas or elsewhere will require much creative thought and energy. It would be a false premise to assume that major breakthroughs will result from this conference, or shortly thereafter, or to hope that a success here or there can translate into a universal solution. The reality, as we see it is that rapid progress and great economies will accrue on any given project only if effective application engineering is carried through. By all means take advantage of past experiences but, do not at the peril of costly undertaking, blindly accept the program of a successful job elsewhere as automatically suited to your project. Tunnel construction in urban areas is at best a difficult undertaking made more difficult in this period of greater awareness of environment, of conservation and of the quality of living by sophisticated urban communities,. A construction job represents a necessary nuisance to urban communities. To minimize this nuisance many regulatory laws are adopted. These regulations can and do slow down tunnel jobs and pyramid costs.

Jan 1, 1974

By Boehme PW, Gregory OR

The results presented here show quite definitely that in the system investigated the intensity of dispersion is enhanced by switching the flow entry from bottom to sides of the packed trough. Since there is no reason to suppose that this would not be true generally then it is not surprising that the blast furnace dispersion data of Standish and Polthier lie above the data for packed columns with bottom fluid entry. In fact, on the basis of the present results, blast furnace dispersion results can never equal standard packed column behaviour but must always be above these. The result that the intensity of dispersion in the trough model is higher closer to the side ports than away from them is at variance with that of Standish and Polthier blast furnace results. Aside from the obvious structural differences between these two systems, it is thought that the presence of raceways and the tortuous path of the gas flow in the furnace may provide an answer. Clearly this is an important difference in the behaviour of the two systems and further investigations designed to clarify the position would have significant practical value. This would also give an indication of how the furnace D/ud values may be decreased along the whole height - assuming of course that this result gives the best overall performance of the furnace. However, there is to date no knowledge whatsoever about this aspect of blast furnace Technology.

Jan 1, 1975

This paper is intended to continue the subject in the light of recent work, from where it was left at the conclusion of the discussion on the excellent paper by the late Mr. Noel Haszard. The position then obtaining is briefly summarised below:-The points which received general agreement at that time were:-'(1) That the gold occurs, probably in an elemental form, in a state of very fine division in the pyrite.(2) That the aim in roasting of Kalgoorlie flotation concentrates should be to obtain the maximum porosity possible. The gold tellurides were amenable to treatment with either a' solution of high lime and cyanide strength combined with fine grinding, or bybromocyanidation without re-grinding.(3) That a low roasting temperature is essential during the elimination of the first atom of sulphur, if the final calcine is to give a good extraction by cyanidation.(4) Even with the best temperature conditions of roasting then determined, and after a period of cyanidation of the calcines until no further extraction was obtainable, the lowest calcine residues obtainable were equivalent to approximately 1·8 dwts. per long ton, based on an original concentrate of pure pyrite.There was some division of opinion at the time as to whether the temperature of the later stages of roasting was significant, and also as to the reason why the initial roasting temperatures had so marked an effect.

Jan 1, 1939

By W. T. Turrall, D. Porter

THE crystal laboratory, Dept. of Physics, Massachusetts Institute of Technology, was confronted with the problem of obtaining a supply of optical grade calcium fluoride (CaF2) for use in growing synthetic CaFe2 crystals. A search of the known fluorspar deposits did not indicate that any quantity of optical spar could be obtained. Even the best material had to be sorted by hand to remove impurities. The process for growing CaF2 crystals developed by Professor D. C. Stockbarger of the Dept. of Physics, M.I.T., necessitates very pure feed materials. Exclusion of impurities is required, even in amounts detectable only spectrographically. The impurities occurred as minute inclusions of SiO2, BaSO4, CaCO3, FeS2, water or air. Crystals up to 4 in. in diam and weighing several pounds are made by the Harshaw Chemical Co. in Cleveland. Since the time required to grow a 4-in. crystal is about one week, and since the cost of manufacture is high, removal of impurities by any concentration method appeared practical. The mineral engineering section of the Dept. of Metallurgy undertook to investigate the possibility of concentrating clear optical fluorspar, -4 mesh +10 mesh, from a feed containing over 99 pct CaF2. Various innovations of the known methods of concentration were considered, but in each case the minute amount of impurities associated with the crystal produced such extremely small differences

Jan 1, 1952

By Louis W. Riggs

The primary concern in dealing with contractual arrangements for construction is getting the work completed satisfactorily, in the shortest time, and for the least expense for the owner--while assuring that all other parties associated with the contract make a reasonable profit for their effort. In our complex construction climate of today, achieving all of these is usually not possible. Somewhere between the beginning of design and the completion of the work, disagreements and delays arise which can destroy the best of intentions. Assuming that all parties associated with the contract are acting honorably and professionally, the disagreements generally arise through inappropriate contract types or through flawed contract documents. These flaws can be either sins of omission or commission, but we must find a way to lessen, if not completely eliminate, their impact. Disagreements and delays are directly related to the extra cost which the owner and the other involved parties must suffer. Usually the attorneys are the only ones who come out on the positive side. Inappropriate or defective contract documents can be the result of inadequate time for preparation and review, laziness in not searching out the proper terms and language, insufficient recognition of the proper assignment of risks, or just ignorance as to what is right and what is wrong for the particular project. They can also result from a client, particularly a public agency, providing rigid general conditions and format requirements with which the engineer is not allowed to tamper. Arguments

Jan 1, 1979

By A. F. Frederickson

A MINERAL can best be defined as a phase,' where the term "phase" is described as a homogeneous,* physically distinct, and mechanically sep- arable portion of a system. If one phase develops from another, certain nuclei must first be available.2.394 The manner in which new material is added to these nuclei, and the subsequent structural and other characteristics of the phase, is often markedly influenced by factors other than its temperature, pressure, and gross compositional environment. Rates of growth, presence of impurities, the availability or lack of oxygen, the pH of the system, and percentage of completion of the often determine which modification will develop. Many transitional phases develop when a relatively insoluble precipitate is formed from solution. Different modifications are formed, depending on the speed and percentage of reacting solution added. Some of these "forms" are stable and do not "age" or transform into the so-called stable modifications. These modifications are difficult to treat in terms of equilibrium diagrams for the simple reason that these minerals do not represent an equilibrium situation described by only two (temperature and composition) or three terms (when pressure is considered). Many crystals exist as stable or meta- stable phases in nature in environments much different from those indicated by certain equilibrium diagrams. Cristobalite octahedra grow on zeolite needles in vugs, diaspore develops from a medium that does not appear to have been subjected to high pressures and temperatures, authigenic feld-

Jan 1, 1952

By Robert W. Thompson, Darry A. Ferguson

In August, 1977 the United States Congress passed Public Law 95-87 which has been commonly referred to as the Surface Mining Control and Reclamation Act (or SMCRA). This title is somewhat misleading in that the act creates as many regulatory requirements for underground coal mines as for surface coal mines. How- ever, this paper will concentrate on the effects of SMCRA on designs and stability for various activities of surface coal mines, specifically those concerning "Disposal of Excess Spoil". In the past, the objective of most laws and regulations applicable to the mining industry has been to achieve goals of safety or environmental concerns for all types of mining. However, SMCRA is unique in that it sought to regulate-all-activities of coal mining from initial data gathering, exploration, mine design and facilities design to reclamation activities and design. More specific to the stability of the activities of surface coal mining, special criteria for design and construction performance standards have been promulgated for the construction and maintenance of roads, dams and embankments, coal processing waste, ex- cess spoil piles, backfilled reclamation and pit slides. The criteria for design for the previously mentioned facilities has been enumerated by regulations and in many ways restrict the use of site specific design parameters. The restrictions imposed by regulations significantly inhibit the engineer's ability to develop the best practical and economical design and in some cases may re-

Jan 1, 1983

By T. S. Krishnan

Among the established permanent magnets, SmCo5 magnet occupies the foremost position as it offers a unique combination of high energy product, coercivity and curie temperature. The SmCo5 magnets are thus extensively used for high field applications. These are also best suited for use in environments where high demagnetising field and high temperature are operative. Also, for applications where high performance and miniaturisation are the over-riding considerations, the choice again falls on SmCo 5 magnets. The main deterrent to the widespread use of SmCo5 magnet is its high cost. Both samarium and cobalt metals are high priced, and the magnets prepared from their directly melted alloy are thus naturally very expensive. An alternate process involving calcium reduction of their oxide intermediates has, therefore, been studied and the alloy prepared by this process has been evaluated and found satisfactory for magnet production. The process essentially involves compaction of the charge mix containing samarium oxide, cobalt oxide (or metal) and calcium metal and' reduction of the charge compact at 1000-1300°C in hydrogen atmosphere, followed by water and acid leaching, drying and classification. The calcium reduction process offers three distinct advantages over the conventional melting processes: (i) The oxide intermediates are relatively cheaper and do not pose any handling problems. (ii) The operation temperatures are comparatively lower and hence precise composition control is possible as samarium losses due to volatilisation

Jan 1, 1989

By F. O. Willhofft

The symposium on mine safety held in connection with the annual meeting of the Institute three years ago, it. was pointed out that "at present no convenient, reliable, accurate means for determining the gas content of mine air is available, for use by the ordinary mine man." In a letter addressed to Coal Age and published on Feb. 25, 1925, Thomas T. Read, then Director of the Safety Service of the Bureau of Mines, stated: "It is to be hoped that sometime in the near future some-one will invent a reliable methane indicator that is con-venient to, use and will permit the keeping of all flames of every character out of bituminous mines, through doing away with the safety lamp." The Martienssen methane detector, which has re-cently received the official approval of the Bureau of Mines, is intended to. meet the demand for such an in-strument as expressed at that meeting and on many other occasions. The characteristics which qualify it for the task are the following: (1) simplicity; (2) small bulk and light weight; (3) ruggedness; (4) accuracy sufficient for the requirements; (5) safety; and (6) dependability. The principle on which the working of the instrument is based may best be explained by giving a brief out-line of the various stages of development through which the inventor, Professor Martienssen of the University of Kiel, Germany, advanced to the final solution of the problem which he had undertaken to solve.

Jan 2, 1928

By Pertti Pekkala

Outokumpu has 25 years of experience in the SX area. The development of the solvent extraction plants responds to an ever increasing demand for lower operational costs wd for adaptability to process disturbances with minimized risks. In this paper the features of the VSF ("Vertical Smooth Flow") SX technology are described, such as the separated pumping and mixing, the homogenous gentle mixing, the droplet coalescence and the ultra pure settling. A major advantage of the mixing technology is the high stage efficiency of above 99 per cent. The connection between this and some features of the settler front section is clarified. The present design of VSF plants is based on experience of existing operations at, for example, Zaldivar, Radomiro, Morenci, Kokkola and Harjavalta. These production plants cover a unit capacity range of 60 to 3,600 m3/h expressed as a total flow. It is evident that there are no restrictive factors to increase the total flow up to 5,000-6,000 m3/h by introducing the VSF technology. The copper SX technology has a long history reflecting many individual features of the separate copper SX plants. Still it is necessary to verify all actual running parameters by pilot tests taking into account impurities, chemicals used etc. The design of SX plants is not only about the delivery of equipment but also a process concept, and it is best tailor-made and adapted to specific local requirements.

Jan 1, 1999

By G. Molloy

The purpose of this paper is to demonstrate the value of applying continuous improvement, in particular 5S and standard work, in an underground environment. 5S and standard work are two aspects of Lean manufacturing that have been applied in many industries. At Vale Canada Limited, the focus is to first stabilize the process, commonly through the use of 5S, standard work and other continuous improvement techniques. In parallel with building an engaged workforce, these approaches aim to incrementally stabilize and improve a process. 5S is an employee-driven, systematic methodology to reduce waste in all its forms through attaining, maintaining, and improving workplace organization. Identified as a foundational part of any improvement process, 5S aims to remove wastes that impact on the overall efficiency of the area. Standard work is used to formulate a common approach to how tasks are carried out to ensure consistency. Standardization involves identifying, establishing, and following the best method. The aim is to eliminate the variation that can occur when there is not a pre-defined established standard. Demonstrating the value of 5S and standard work in an underground environment will be achieved by first understanding the overall concept of Operational Excellence and continuous improvement as practiced within our operations. The paper will then cover a real application of 5S and standard work within the underground environment at Thompson, Manitoba.

Aug 1, 2013