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By Christopher Mark

Horizontal stresses are caused by global plate tectonic forces. During 1995 alone, they were largely responsible for closing two U.S. longwall mines. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky, and Alabama. In each case history, a mine encountered roof falls or difficult ground conditions in the headgate, caused by horizontal stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble-free. The paper also discusses detailed measurements made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel with the maximum horizontal stress, as previously thought, but rather 20° in the stress shadow of the gob. Other stress control techniques, including artificial support, are briefly discussed.

Jan 1, 1997

By K. Biswas

For the pillars, which have been standing long after mining, the stability depends much on the weathering action in the presence of mine moisture. From the field observations, it has been found that this weathering action becomes critical in terms of pillar stability if the coal seam contains partings or binders in it. The weathering action degrades both the partings and coal in terms of their load bearing capacity as the mine moisture penetrates into them. This paper investigates the effect of weathering action on coal and partings in the laboratory. In the field, the strength profile in the coal and the partings and the effect of time (in terms of the pillar age) on them have been studied by using borehole penetrometer. In this paper, an attempt has also been made to establish formulae for time dependent strength of coal and partings.

Jan 1, 1997

Since the beginning of the computing age, technical software packages have not been developed to address only programming specialists but have been dedicated to process engineers. For process analysis, BRGM is developing and commercializing three packages: ? sampling software: ECHANT 2.0 for Windows ? material balance calculation: BILCO 2.0 for Windows ? steady-state simulator for plant design, adaptation and optimization: USIM PAC 2.1 for Windows This paper deals in a first part with the main features of these three packages. In a second part, advanced models are presented for SAG/ AG mills and flotation columns. An industrial case of application is shown for each of them.

Jan 1, 1997

By Andreas Nolte

This paper includes a comprehensive report about the metallurgical utilisation of reusable products from electronic scrap recycling, car shredding industry, used glasses an various waste products, such as slimes and flue dusts, generated in a secondary copper smelter. Depending on the copper content, the type of copper compounds and the characteristics of accompanying substances, the materials are treated by smelting in furnaces, operating under reducing or oxidizing conditions. HKs pyro- and hydrometallurgical processes, blast furnaces, converters anode furnaces, tin lead alloy plant and tankhouse will be outlined. The reusable products are categorized according to the origin of the materials and then presented in the form of quantity and quality balances. Processing methods, process able quantities and quality requirements of inputs are described. The utilization degree of the most important metals (copper, tin, lead and zinc) is described with graphics. The report is rounded by information on operating licence according to the environmental regulations of the Federal Republic of Germany and data concerning supply and contracts

Jan 1, 1997

By Michael D. Justason

This paper details the static and Statnamic load testing on a 600 mm square pre-stressed concrete pile. The pile was located at Pier 15 on the 20 million-dollar Bayou Chico Bridge Project in Pensacola, Florida. The pile was 10.5 meters long and had a design load of 1.3 MN. Three static load test cycles were performed in November, 1996. The Statnamic load test was performed in January, 1997. The Davisson Failure load of the first cycle of the static test was 3.7 MN, and the Davisson Failure load of the Statnamic test was 3.2 MN. The load-displacement curves for the two types of tests were very similar, indicating that the Statnamic load test performed well in the sandy soils. Strain gauges embedded in the pile showed 35% skin friction and 65% end bearing for both test methods. Strain gauges were located at equal spacing at five elevations in the pile. A toe accelerometer verified the rigid body assumption of the Unloading Point Method currently used in the analysis of Statnamic load tests. The data collected from the pile instrumentation was of excellent quality and represents some of the best research to date comparing static and Statnamic load tests.

Jan 1, 1997

By Guo Chang Jiang

In order to improve the IIAZ toughness of X-60 pipe steel, the intragranular ferrite plate (IFP) technology was used. The characteristics of IFP is claimed to be much fine ferrite plates appear inside the original austenite grains. By means of suitable Re, Zr, Ti additions in a bath with a higher initial oxygen potential, a good control of the peak temperature and the cooling rate during welding simulation, one can get a %IFP in volume over 50%, and the toughness gets up from 55 J to 160 J. It was found that the inclusions most effective in nucleating IFP are some deformable complex silicates which either entrap Re, Zr, Ti oxides or contain these elements. The greater the number of the evenly distributed and effectively nucleating inclusions, the more the %IFP in volume, and the finer the microstructure of the HAZ, so the better the relevant toughness. Generally, these silicates bahave as fine spheres along a line. The present authors revealed that these fine spheres result from the remelting of the shuttle- like silicates due to heating in the process of welding simulation. These silicates used to get a higher sulphur capacity, so MnS deposits might be observed on the periphery of the silicates. IFP was proved to be directly rooted in the [Mn] depleting zone which locates beside MnS deposits.

Jan 1, 1997

By G. M. Card, K. D. Card, B. V. Sanford

Abstract-The Canadian Shield and its extensions are traversed by an orthogonal system of northwest and northeast trending arch-style uplifts. These basement arches were formed by repeated vertical movements along pre-existing structures during compressional and extensional tectonism connected with events in surrounding Proterozoic and Phanerozoic orogens and ocean basins. The arches influenced patterns of sedimentation and tectonism in the intervening epicratonic basins and marginal platforms throughout the Proterozoic and Phanerozoic. Movements on the arch structures also triggered minor magmatism and controlled the location and timing of alkalic rock-carbonatite, kimberlite, and related intrusions in the Canadian Shield, the Western Canada Sedimentary Basin, and West Greenland.

Jan 1, 1997

By Jack E. Thompson

I have spent my entire life in the mining industry pursuing what I believed was an honorable profession that provided products that were critical for our social and economic well being. Now I am told that all of my efforts been for nothing and that I have been doing something morally wrong - mining. This view of the future is not one that the mining industry has to allow to unfold. A determining factor in how things will turn out is continued improvement of the industry's environmental performance. To some extent, the current state of affairs in the United States is a result of the common perception that greedy corporations (usually foreign) are somehow ripping off US citizens of their native birthright or natural treasures in the name of corporate profits. Implicit in this view is the belief that corporations will take shortcuts or violate the environment in the name of profits. I have 26 years of experience in working in the copper, uranium and gold industries. Profits during those years were meager and difficult to find (Fig. 1). In fact, when I began working fresh out of college, I chose copper, which was then selling at around $1/lb. By the time I left copper mining, it was selling for 45 cents/lb. I then moved to uranium, which was selling for $52/lb. By the time I left it was $16/lb. I finally picked gold, which was then at ($650/oz). There is a whole generation of engineers, geologists and professionals who have spent two decades downsizing, closing mines, improving costs and getting smarter about how the mining industry does what it does. The environment, health and safety are areas where there have been great improvement. There are five characteristics of corporate governance that are critical for a company to develop and an industry to embrace if environmental, health and safety excellence is to reach new heights in the labor pool.

Jan 1, 1997

By R. M. Barker

The historic Getchell property is currently being mined from the Getchell Main Underground workings, a foot wall extension of the Getchell open pit deposits along the Getchell fault. Drift-and-fill techniques are used to extract the ore through a ramp access. The adjacent Turquoise Ridge deposit is currently under development via two vertical shafts. Together, the two mines will continue to provide feed to the Getchell's 3,200 tpd mill/autoclave circuit, taking Getchell Gold from its current production rate of 200,000 ounces (Au) per annum, to over 400,000 ounces (Au) per annum by 1999.

Jan 1, 1997

By D. M. Richards

"IntroductionThe Highland Valley Copper partnership was formed in July 1986 as a logical result of a mine with a large ore reserve but a small mill, and a mine with a large, modern mill but dwindling ore reserves. The original partnership of Cominco and Rio Algom was expanded in January 1988 to include Highmont Mining Company. During 1988/89 the Highmont mill was moved 7.5 km to adjoin the Lornex mill, becoming the Highland mill in the process, with a nominal capacity of 130 000 tonnes per day.The mine is located near the town of Logan Lake, 220 km northeast of Vancouver, British Columbia and 55 km southwest of Kamloops. The map in Figure 1 shows the general area. Kamloops is a major service centre and is served by two railways, two major roads and a regional airport. The mine site is situated between 1200 m and 1600 m above sea level on the Thompson Plateau. Principle activities in the area, in addition to mining, are cattle ranching and forestry. Ore reserves at the beginning of 1996 totaled 533 million tonnes at a grade of 0.42% copper and 0.008% molybdenum. Ore is mined from two pits — Valley, 3 km northwest of the mill; and Lornex, 1 km southwest of the mill. With 78% of the reserves, the Valley pit is the focus of activity.In order for Highland Valley Copper to remain competitive with a very low grade ore reserve, it has been necessary throughout the mine’s life for new technologies to be embraced as they become available. These have included such diverse technologies as in-pit crushing and conveying, large mechanical drive trucks, computerized truck dispatch and oneman survey instruments. During the next few years, it is planned to introduce two further technologies that are relatively new to both the world at large and the mining industry in particular. These are namely Global Positioning Systems (GPS) and Geographical Information Systems (GIS), both of which are expected to have a major impact on the way mining is carried out in the years to come."

Jan 1, 1997

By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral-processing circuits. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed. This practice may be attributed to a poor understanding of the factors that control throughput. The use of tall flotation columns is frequently justified because of the need for an increased particle residence time. However, it is shown that longer particle residence times alone do not translate into increased recoveries. In this paper, throughput data from several industrial flotation-column installations is presented. Also, an attempt is made at using dimensional analysis to provide a scale-up methodology for the factors controlling column throughput.

Jan 1, 1997

By C. A. Rawlins

INTRODUCTION Radcont is a program designed by the author of this paper for the industry to use as an instrument for radiation contamination evaluation and ventilation planning system. Radiation in mines are associated with the mining of gold and gold bearing minerals, as uranium and thorium is incorporated in the mining of these minerals. Radiation contamination in South African mines is not a new concept as it was investigated by the Chamber of Mines in the early 1960's and found not to be hazardous at the time. Since some of our mines export scrap metal to customers abroad, it came to light (1991) that some of the scrap metal was radioactive. The authority that oversees the nuclear aspects in South Africa is the Council for Nuclear Safety (CNS). They investigated these matters and found that the mines needed further information regarding radioactive material and the handling of these contaminated materials. As the various mines were licensed (with various conditions incorporated) thereafter, the mines had to do their own investigations as to what extent their properties (Surface and underground) were radioactively contaminated. Some mines were found to be highly contaminated over the years of operation and controlling conditions were installed and measures installed to reduce the contamination levels. One of the conditions when issuing a licence by the Council for Nuclear Safety (CNS), is that a screening survey be carried out to determine the radiation exposure levels and corrective action to be taken if necessary. These surveys must be done by a person trained in the required procedures for such a survey. The person must also measure the risk correctly and assess the results properly. In such a survey, the internal and external exposure levels must be determined to assess the total exposure of persons working in those conditions and take appropriate action if necessary. When doing such a survey, hundreds and more likely, thou- sands of data points are recorded. In order to assess the data recorded, various integrated and difficult calculations need to be made, and takes up enormous amounts of time. (This excludes the interpretation of the results ) The following explanation of the program shows the different parts of such a survey assessment calculations to be done. The paper details the program layout and the different sub- sections within the primary program. It must be stated that the program, as with any other program, is as accurate as the data inserted into the data base. The program and details thereof are given under the following headings: 1. TOTAL EFFECTIVE DOSAGE WITH REGARDS TO: • GME required gravimetric results obtained (mg/m3) • Thick layer or total contamination measured (Bq/m2) • Dry condition surveys with dust loads taken as a Standard l0mg/m3 • Wet conditions survey with dust loads taken as l mg/m3 • Airborne long lived alpha and beta activities as determined by analysis in Bg/m3 • LTD (Thermoluminescent Dosimeter). Results as obtained from the SABS (South African Buro of Standards) are recorded in this section for each month of the year for each individual worker. An average dose is then determined at the end of the year. • Bucket measurements as recorded. • Smear samples (Loose contamination). As determined by Electra or by analysis • Occupational factors for Metallurgical and Engineering occupations in and around the Metallurgical facilities of your mine. • All underground dosage determination and calculations. (Radon and Thoron) 2. INFORMATION REQUIRED WHEN PROGRAM IS INITIALISED: As the program is started, it opens up on the contents page. Here there are various options to choose from, but one is cautioned as a beginner in operating the program, not to perform any tasks before carefully reading these instructions. Firstly, one must go to the 'Information required" pushbutton. Press this button. The information required page is shown where the cursor can be moved to the block where one can enter the specific mines name. To enter a mines name, put the cursor in the block provided and just insert the mines name with the normal keyboard keys and press the enter button on the computer keyboard. To enter the other information required such as Alpha and Beta instrument efficiency, ALI (Annual limit of intake) and probe area, one can either press the 'Data required" button for a dialog box information or enter it manually by just putting the cursor in the block provided and entering as did above. In order to insert all the required information for the pro- gram to calculate the information required, one must proceed further by entering the area names surveyed in the spaces provided. There are 20 spaces to enter 20 different areas surveyed. One must further also provide the amount of days worked in each area (i.8. 250) in the block provided. The de- fault is 250 days. There are also standard information given in the information data page such as breathing rate (1,2 m31h), 8 hours worked per day, 5 days per week and 50 weeks per

Jan 1, 1997

By A. Korbel

The progress in understanding the nature of strain localization in metallic materials and in particular the understanding of the role of external (deformation conditions) and internal (material substructure) factors in the development of the tendency toward concentration of plastic flow within transgranular shear bands was the background of the concept given in the title. Following this idea, the practical possibility of replacing the homogeneous in a micro scale mode of deformation by transgrasnular shear bands gives a chance to change the arrangement of the dislocation substructure in the material from that typical for homogeneous deformation into long wavelength (transgranular), pseudo-periodic dislocation walls. The presence or formation of such a substructure in a thermodynamically unstable matrix may result in the formation of the products of phase transformation along shear bands, giving rise to a composite-like structure. This work is aimed to provide a coherent justification to the concept of Natural-Metal-Matrix Composite and summarizes the results of experimental works in this area.

Jan 1, 1997

By Waldemar W. Koczkodaj, William O. MacKasey

A consistency-driven pairwise comparisons method for mineral potential assessment is presented, using a simpli?ed case of volcanic-associated massive sul?de type deposits as an example. Geological, geochemical, and geophysical criteria are considered on two levels: local and regional. The local geological criteria are subdivided into stratigraphy, lithology, alteration and/or mineralization, and structure. The concept of geomerit index and a procedure for computing this index are introduced. The method of consistency-driven pairwise comparisons can be combined with other quantitative and qualitative assessment methods, enhancing them by incorporation of non-measurable geological criteria (e.g., stratigraphy or lithology) and by computation of weights. The consistency-driven approach allows experts to re?ne at-times subjective judgments concerning exploration and land-use planning, and contributes to the improvement of mineral-potential assessments.

Jan 1, 1997

By Kagl J, Publlier M, Nekitel S, Arumba J, Rangin C, Mosusu N

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

By J. R. Evans

In order to patent an industrial mineral placer mining claim, it must incorporate an economic deposit. Each ten acre parcel is evaluated for its mineral -in -character nature. Nonmineral -in -character parcels cannot be patented. Economic concerns include: claim locations, dummy locators, common variety nature, "excess reserves," and environmental constraints. Also, geologic and mineralogic studies, sampling and testing procedures are vital. Mining, milling, processing cost, and taxes must be evaluated. Product marketability analysis is necessary before starting any cash flow or discounted cash flow study. Valid data is essential to evaluate an economic industrial mineral deposit.

Jan 1, 1997

Miners and explorers in New Zealand are expected to consult with stakeholders, keep out of core conservation areas, and operate a high standard of environmental management and rehabilitation. These requirements are not difficult to meet, but many of the industry's own actions have brought it to a low level of general public esteem in New Zealand. Reasons for this are discussed, drawing examples from the Maruia Society's experiences with the industry since the mid-1980s. The boundary between core conservation areas and other land is not easily drawn, and the Maruia Society has sought to work with the mining industry to promote legislation for net conservation benefit trade-offs. However this initiative was not successful. Today the industry, unlike most other major industry sectors in New Zealand, has no accord with the country's conservation movement.

Jan 1, 1997

By M. R. Barkhudarov

Semi-solid metal can be formed into useful products of near net shape and high quality. Use of this method has been limited, however, because of the difficulty of working with metal in the semi-solid state, which has strong shear rate, temperature and time-dependent properties. In this paper we describe a thixotropic model and apply it to the problem of small metal droplets impacting on a flat plate.

Jan 1, 1997

By Jennifer Mager, G. P. Martins, Dean Mussatti

"The role of lead, at low concentrations in high pH cyanide-electrolytes, on the dissolution behavior of gold, has been a topic of scientific and industrial concern for well over a century. The recent paper by Kondos et al [1] at CANMET (1995) this continuing interest and apparent importance. Nevertheless, the mechanism(s) by which this (and other heavy metal) component influences the electrodics of this electrochemical system has still not been unequivocally demonstrated. Instead, several plausible hypotheses, by pioneering researchers in this field, have been advanced and reiterated OVer the ensuing years. While it is generally accepted, based on equilibrium elctrode-potential calculations, that reduction (or co-reduction when oxygen is present in the electrolyte) of lead on the gold surface may occur due to cementation (contact reduction), the cemented lead has never been characterized. The work presented has reexamined the role of lead in this system, by delineating the species distribution of these system components and by interpreting the results of potentiodynamic studies in conjunction with SEM analyses of a gold electrode.1. INTRODUCTIONThe leaching of gold ores in cyanide electrolytes has been practiced for well over a 100 years. Research conducted on this topic has been primarily focused on the effects of operating parameters such as concentrations of oxygen and cyanide, and the pH of the electrolyte; or the leaching behavior of carbonaceous and sulfitic gold-bearing materials.Mechanisms by which pure gold is leached in alkaline cyanide media, with oxygen serving as the oxidant, have been subjected to continual examination and re-examination in the published technical literature during this century. Recently, it has been speculated that without the presence in the electrolyte of trace heavy metals, such as lead or mercury, that gold would not be leachable. Researchers who have tackled this topic, have either considered heavy metals to be a natural occurrence in these systems and ignored the role they may serve in the leaching process, or they have deliberately focussed on controlling their concentrations in the system to undetectable limits. As a result, conflicting findings have been reported for what would appear - depending on the details provided in these reports - to be identical systems."

Jan 1, 1997

By Harold L. Gibson, Don H. Rousell, Ian R. Jonasson

"The Sudbury Structure consists of three major components: 1) the Sudbury Basin; 2) the Sudbury Igneous Complex which surrounds the basin as an elliptical collar; and 3) an outer zone of shatter-coned and intensely brecciated footwall rocks. Although the Sudbury Event which formed the structure may be unique, the area has, in fact, been shaped by a series of tectonic, magmatic and mineralization events which can be considered in terms of two Wilson cycles of continental extension and closure. The first cycle, from 2500 to 1700 Ma, included the following events: doming (uplift of Levack Gneiss Complex); NE-SW extension (Matachewan dikes); N-S to NW-SE rifting (faults, mafic intrusions, sedimentation, and Ni-Cu-PGE and U mineralization); NW-SE extension (Nipissing diabase, and Ni-Cu-PGE, Ag, Co mineralization); and NW-SE and NE-SW closure (Penokean Orogeny, 1900 to 1700 Ma) with superimposed meteorite impact (1850 Ma, Ni-Cu- PGE, Zn-Cu-Pb deposits). The second cycle, from 1700 to 1000 Ma, included: N-S extension (alkali metasomatism, Au); N-S extension (hornblende diabase dikes along the Murray fault set); NNESSW extension (olivine diabase dikes); NE-SW extension (Fecunis Lake fault set); and NW-SE closure (Grenvillian Orogeny).The rich and diverse Ni-Cu-PGE and subordinate Zn-Pb-Cu and Au mineralization of the Sudbury region is related to endogenic and impact-triggered crustal extension and magmatism. The Sudbury Structure apparently was the site of a triple junction or hot-spot. The Sudbury ores, although located within an impact structure, are analogous in terms of age and tectonic setting to Ni-Cu-PGE and Zn-Pb-Cu ores elsewhere in the world. Meteorite impact accentuated on-going ore forming processes and magmatism at Sudbury."

Jan 1, 1997