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By Norbert Steiner, Roy Norcross

For the desulfurization of weak SO2 gas streams, Degussa developed a process using dilute H2SO4 solution containing H2O2 instead of conventional gas scrubbing with all solid absorbent medium (limestone, MgO). The process is based on fast reaction of H2O2 with SO2 yielding H2SO4 up to 70% strength, depending on off-gas tem­perature. Compared to the conventional systems with typically < 95% efficiency, independent on the raw gas SO2 concentra­tion, residual SO2 concentrations of less than 20 mg!Nm3 can be easily achieved, corresponding to nearly 100% removal. These features render the H2O2 process a very attractive, low capital cost technology to retrofit existing conventional desulfurization plants.

Jan 1, 1996

By M. Akram

Stability assessment of entry roofs is an essential precursor to all underground design. Both multi-seam interaction and longwall mining can subject entries to radical changes in the surrounding stress field. Such loading changes frequently produce instability and failure in the roof, floor and pillars. Roofs are shown to be vulnerable to stress-induced failures, particularly when the load is unsymmetrical. To predict the effects of changes in stress field, roof failure conditions under increasing loads were studied using finite element analysis and body loaded photoelastic models. A large range of geologic conditions were evaluated and incorporated into the model using Monte Carlo methods. Entry analysis using the model showed the roof to be particularly vulnerable to shear with the location of the failure site changing to meet loading and geologic conditions. Results were correlated with field data to determine stress levels at which failure could be expected to occur. Based on this research a roof stability model SESAME was constructed for roof stability evaluation under specified loading conditions.

Jan 1, 1993

By William M. Turner

Thermonics is a methodology of ground-water flow system analysis based upon the distribution of heat within the subsurface as influenced by moving ground water. Thermonics is based upon the Stallman Equation 1 (1) which describes the simultaneous transfer of heat through a porous medium which contains moving ground water. The Stallman Equation is:

Jan 1, 1980

By R. L. Kloberdanz

Compania Minera Disputada de las Condes S.A. (Disputada) is proactively implementing closure and reclamation planning activities at its mining and beneficiation facilities (mining facilities) in Chile where regulations governing mine reclamation are not yet fully in place. These activities are being implemented to improve currently employed measures to protect human health and the environment and to enhance reclamation and facilitate future closure with regard to these areas when mining is completed. As part of this process, Disputada, with the assistance of Shepherd Miller, Inc., developed recommendations and guidelines for future closure and reclamation of the Disputada sites. These recommendations and guidance incorporate planning and operational and post-operational design considerations and practices, and standards used by the mining industry and regulatory agencies around the world. The criteria presented in the guidance are based on achieving conditions that will be suitable for the anticipated post-mining land use. This paper discusses the process and approach taken, and the results.

Jan 1, 1999

By L. M. Nuelle

Rare earth element (REE)-and gold-bearing breccia pipes are a potentially significant economic target in the Pea Ridge iron ore mine, Washington County, Missouri. The Pea Ridge deposit is one of eight known volcanic-hosted iron ore deposits in the Middle Proterozoic St. Francois terrane, which are similar to the Olympic Dam-type deposits of Australia. The iron orebody is steeply dipping, tabular-shaped, and cuts across the host rhyolite. The footwall of the deposit is zoned from the massive apatite-bearing magnetite core outward to heterolithic breccia, pseudobreccia, specular hematite zone, to an extensive silicified zone. The hanging wall is zoned from the massive magnetite core outward to a heterolithic breccia, pseudobreccia, and an amphibole skarn zone. The REE-rich breccia pipes cut through the various lithologies along the footwall at or near contacts. They are typically 60 m long, 15 m wide, and extend at least 120 m vertically. The pipes are comprised of fragments of rhyolite host rock, massive magnetite zone, specular hematite zone, and silicified zone rocks supported in a matrix of rock flour, barite, feldspar, monazite, apatite, chlorite, xenotime, and, locally, gold. Total REE oxide content of samples of the ground mass material, which are not diluted with lithic fragments, average about 20 weight percent. Grades from working faces in the mine are lower and average about 12 weight percent. Gold distribution is erratic, but concentrations are as high as 371 parts per million.

Jan 1, 1991

By Barry J. Hansen

Mining can make two major contributions to the cleanup of the environment. The first of these is the extractive technology that has become highly developed as a result of centuries of development. Of equal impor­tance are the methodology of analysis and the development of engineering solutions that are the stock in trade of the mining industry. Despite the differences between the industries, the processes for the development of a mine and the cleanup of a hazardous waste site are similar. The characteristics that impact the ability to develop a suitable process for treating an ore body or correct­ing an environmental problem are those relat­ed to the distribution of the contaminant or metal in the host material.

Jan 1, 1991

By Dean S. Rogers, R. A. Metz

The conventional role or exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Mine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world&apos;s classic Archean gold deposits.

Jan 1, 1992

By C. Douglas Lee

This case study describes the work done at the University of Arizona on the development of a computer mine model for an irregularly shaped and spotty ore deposit. The purpose of the work was to develop techniques for modeling any highly irregular deposit, for which the regular 3D fixed block model is not well suited. The deposit contained complex geology consisting of sedimentary beds that had been faulted, thrusted, and intruded by igneous rocks (see Fig. 1). The physical dimensions of the modeled ore body were 1067 m (3500 ft) along the N-S direction and 914 m (3000 ft) along the E-W direction. Topographic relief in the modeled area was approximately 274 m (900 ft). The highest grade of ore was found near the surface with mineralization extending down to approximately 152 m (500 ft) below. Using a fixed bench height of 12 m (40 ft), the model required 25 levels with the highest elevation being at 1286 m (4220 ft). Fig. 2 shows a cross section of the developed computer model of the ore deposit. The particular modeling approach selected for this deposit was the 3D irregular block model.* This meant that only the dimension of bench height was fixed at 12 m (40 ft). Irregular size blocks in the form of polygons were adopted in the model to describe the ore zones and geologic contacts. The following sections of this chapter describe some of the techniques used in modeling.

Jan 1, 1979

By Satid Therdkiattikul, Donald A. Dahlstrom

Many gold ores are known to be refractory so that conventional cyanide processing will result in serious losses of gold and silver values. A significant percentage of these refractory ores contain aresenopyrite and the gold and silver is usually encapsulated within this matrix as well as the pyrite matrix. Normally the values can be recovered as flotation concentrates because of the sulfide compounds with recoveries of over 90% and at very good grades. In order to free the gold and silver, the sulfide matrix must be destroyed. This can presently be achieved by (1) pressure­temperature leaching (2) roasting and (3) bacterial leaching. All of them have advantages and disadvantages as well as an obviously increased cost for the each processing method. However, the increased gold and silver recovery should and must more than offset this cost. It is believed that gold recovery should be well over 90% from the concentrate so that overall recovery from the ore should be in the 90-95% region. All three processes must consider pollution control of both sulfur and arsenic to prevent contamination of air, water or land through improper waste disposal. This paper will concern only bacterial leaching and its necessary control of effluents and solids. Sulfur does not appear to be a problem as the element is oxidized to sulfate and is precipitated with an acceptable solubility. Other important improvements that must be controlled are arsenic and iron which are present as significant values (1-12 g/1 of arsenic, 20-40 g/1 of iron). In addition much smaller values of base metals, aluminum and magnesium can be present as well as other elements depending on the ore and these must be low enough after treatment to meet EPA regulations.

Jan 1, 1993

By R. R. Graham

Echo Bay Minerals operates a 650 tpd gravity float gold circuit at their Manhattan facility. The objective of this paper was to document the gold recovery by size distribution. This was accomplished by studying the material balance of each size fraction as it progressed through each gravity Circuit separator. It proved to be an impossible task. Figure I depicts the gravity circuit. The gravity cyclone underflow goes to two duplex Pan American type jigs. The jig overflow reports to the OK Flash Float Cell. The cyclone hutch product is reground and goes to a full size wilfly table. The rougher table concentrate reports to a pilot size Wi1fly cleaner table. The cleaner and rougher table tails circulate back to the jig feed. The gravity circuit was composite sampled for two to four hours per day for four days. Each sample was taken every 20 minutes. Each composite sample was filtered, dried, repu1ped, and screened through a wet/dry screening procedure. Each size fraction was checked for gold value by fire assay fussion technique. A material balance was run on each size fraction. The tables listing the results are enclosed.

Jan 1, 1989

By R. R. Swanson

Liquid ion exchange is becoming more and more important in hydro-metallurgical processing and recovery of metals. The key to success for this process are reagents which have suitable operating characteristics. One of these important characteristics is a relatively fast phase separation rate in the extraction and stripping circuits, as this greatly affects the size of plant required. A test for measuring phase separation rate is needed to help evaluate liquid ion exchange reagents. Such "a test also would be useful for evaluating carrier solvents that are used for diluting the re-agents. In fact, one standard test method would be very desirable as it would provide a common basis for comparing reagents and sol-vents. The phase separation test described in this paper has been used successfully for several years with the copper reagent, LIX®64N. The test is set up for feed liquors containing low copper concentrations. For other types of systems, modifications in procedure probably would be necessary. However, this test and the associated apparatus could be the basis for a standard phase separation test.

Jan 1, 1972

By K. C. Ko, M. D. Bunnell

The studied coal mi1e is an underground coal mine located in the northern Wasatch Plateau of central Utah (Figure 1) . Since operation began in 1981, in situ stress conditions have been encountered which differ from the assumed conditions utilized during early mine design efforts. Geologic structures also varied somewhat from those projected during initial geologic interpretations of the area. The encountered geologic conditions combined with the unusual stress conditions prompted a combined study of in situ stress and stress-related geologic structures. The study was conducted in two phases, with phase 1 consisting of detailed underground mapping and analysis of stress-related geologic structures to determine stress orientations from which they originated; and phase 2, consisting of over- coring two sites within the mine to determine present in situ stress orientations and magnitudes. GEOLOGIC ANALYSIS Three types of geologic structures have been encountered in the mine that act as indicators of stress orientations of the geologic past. Two of these structures, faulting, and igneous dikes, are directly measurable in the mine. A third type of structure, photolineation, was detected through remote sensing methods and shoe god correlation to roof conditions in certain areas of the mine. Faults Two major orientations of faulting have been encountered in the studied coal mine, including a system of N 80 W striking normal faults and a system of N 55 to 70 W striking oblique-slip faults. Only data collected from the oblique-slip faults were used for this study due to the fact that these faults offset the N 80 W faults wherever the two systems intersect, indicating that the N 55 to 70 W system was created by a more recent stress field. Figure 2 shows locations within the mine where data were collected from seven locations along oblique-slip faults. Data collection consisted of measurement of fault plane strike and dip, fault slickenside trend and plunge, and slip direction. The data are tabulated in Table 1. The fault data were then plotted on stereo nets to determine the stress orientations present at the td of faulting (Figure 3). The determined stress orientations are 32~0 included in Table 1. The stereo net plots show average principal stress orientations of: 1) [ ] plunge 1 degree. These data suggest that the N 55 to 70 W oblique-slip faults were produced by a nearly

Jan 1, 1986

By J. Ludden

By Sims Some two years ago we began investigating low coke button bituminous coal for use at our Bound Brook, New Jersey plant as a replacement for anthracite. Since August, 1957 the plant has been operating continously on this coal with the exception of a new 200,000#/hr, cyclone boiler. This study was motivated not from our desire to conduct combustion research, but for the sole purpose of reducing our steam costs, The indications were that the economics were greatly in favor of the use of the bituminous coal. The attempts to reduce the costs have developed some knowledge that has enabled this program to succeed reasonably well as will be discussed later by Mr. Ludden. The production of steam size anthracite is dependent upon either the reclamation of old culm banks or the breakage in the production of the domestic sizes. The anthracite industry has not as yet been able to cut, its mining costs to the point where the production of steam sizes has become a profitable business. This has resulted in two basic problems: (1) A constantly rising price in an attempt to have those sizes carry their share of the cost and, (2) Periodic shortages of supply when the demand is good but the market price prohibits the mining of anthracite to produce those sizes only, These conditions have made the long range forecast appear as though the price would go even higher and/or the supply at times be critically short.

Jan 1, 1958

By Henry E. Swanson

In the early 1960&apos;s the Company, then named the United States Smelting Refining and Mining Company, was drilling the Continental ore body located near Fierro, New Mexico. Reserves of underground ore of sufficient quantity were indicated to build a mill. At the same time some ore from the Continental No. 1 mine was being milled at the Company&apos;s Bullfrog Mill, formerly a lead-zinc mill. The copper ore in comparison to the lead-zinc ores was very hard, abrasive, and heavy. These factors pointed out the possibility and attractiveness of autogenous grinding. While prior to this some study had been given to autogenous grinding, no large scale tests had been made. Such a program was carried out and from the pilot plant data the following was established: 1. Grinding of the ore by autogenous means could be accomplished. 2. This could be done in one stage; however, not at a satisfactory tonnage throughput rate. Thus, the use of a secondary unit has been employed. 3. Grinding in the secondary unit could be done by pebbles generated in the primary unit. This resulted in the scheme whereby the ore would be ground 100% autogenously. 4. Liberation of the copper minerals was excellent so that good recovery at a satisfactory concentrate grade would be obtainable.

Jan 1, 1976

By W. J. Atkinson, E. M. Anderson

FOREWORD This paper is based on the authors&apos; experience gained in the environmental assessment of major uranium projects in the former Department of Science and the Environment and Department of Home Affairs and Environment of the Australian Government. The authors gratefully acknowledge assistance received from colleagues within the Department of Home Affairs and Environment in the preparation of this paper. Special thanks go to Mr K.E. Thompson of the Department&apos;s Environment Division for his valuable comments and criticism. The views expressed in the paper are those of the authors alone and not the Australian Government or Dames & Moore. INTRODUCTION Uranium has been mined in Australia since 1954. A number of small scale mining and milling operations were active in the Northern Territory, in South Australia and in Queensland in the late fifties and early sixties. However, in the late sixties there was an increase in exploration activities in the expectation of an upsurge in world demand for uranium Substantial new resources were delineated in the Northern Territory, Queensland, South Australia and Western Australia. The most significant deposits were located in the Northern Territory, in what is called the Alligator Rivers Region located approximately 200 km east of Darwin. The Region is in the latitude of 13° South and thus lies within the Australian tropics (Figure 1). It consists of approximately 2.3 million hectares of natural wilderness containing much spectacular and attractive scenery. The area is noted for its abundant wildlife, particularly the waterbirds that gather on the flood-plains. Much of the vegetation is diverse and interesting. The Aboriginal population still maintains elements of the traditional way of life, and the spectacular Arnhem Land escarpment contains many of the best surviving examples of Aboriginal rock art. Numerous rich archaeological sites provide evidence of continuous human habitation for tens of thousands of years. Climatically, the Region is of the tropical monsoon type with a dry season from may to September and a "wet" from November to March. High intensity short period rainfall is characteristic, and the average annual precipitation is in the order of 1 350 mm. The monthly mean temperature ranges from 25° to 30°C throughout the year. The development of regulatory controls on uranium mining in the Alligator Rivers Region has been affected by the political status of the Northern Territory. While Australia is a federation, established as an independent self-governing country in 1901, it was not until 1978 that the Northern Territory became to any real extent self-governing. Prior to 1978, the Territory was administered through a special department of the Commonwealth (ie. the Federal Government). Under the Northern Territory (Self Government) Act 1978, administrative powers similar to those possessed by the Governments of the six founding Australian states were provided to the Territory Government. However, the Commonwealth government did not transfer to the Territory all such powers and functions, and in particular there has been, since 1978, a dual role for the Commonwealth and Territory Governments in the regulation of uranium development. Details of this role are provided later in this paper. RANGER URANIUM INQUIRY By 1973, major deposits had been discovered in the Alligator Rivers Region at Nabarlek, Ranger, Koongarra and Jabiluka. The estimated reserves and mine life expectancy of these deposits are given in Table I. Other radioactive anomalies have also been identified in the area but, as yet, they have not been delineated or evaluated. [ ] In 1974, an agreement was signed between the Commonwealth Government and Peko Mines Limited and the Electrolytic Zinc Company of Australia Limited for the joint development of the Ranger deposit. In July 1975, the Government announced a Commission of Inquiry under the provisions of the Commonwealth Environment Protection (Impact of Proposals) Act 1974, into the proposed Ranger development. The inquiry was known as the Ranger Uranium Environmental Inquiry or more commonly, the Fox Inquiry after the presiding Commissioner, Mr Justice Fox.

Jan 1, 1981

By P. G. Semple

For the last four years, the Kilborn Group of Companies has been involved in several major projects in the Confederation of Independent States (CIS). These include the Kumtor project, the Kubaka gold project, the Kazgold project, the Aginskoe project and the Jerooy project. These projects are all in various stages of detailed engineering and construction. Western mining companies are pursuing mining opportunities throughout the world in search of ore bodies for development. The quest for profitable mining ventures has led mining companies to South America and Asia and, more recently, to the former Soviet Union. When considering the CIS, several factors should be considered. The most notable are geography, mining culture and previous mining production.

Jan 1, 1996

By Volkmar Niemitz

Approximately 30 miles east of Chicago on the southern shores of Lake Michigan stands Bethlehem Steel&apos;s newest fully integrated steelmaking facility - the billion dollar Burns Harbor plant. The initial phase of "green field" construction that began in 1963 was directed to the creation of high quality finishing facilities. In late 1964 the 160" plate mill came "on stream" followed closely by Sheet and Tin and Hot Strip facilities. Unit train shipments of slabs primarily from the Lackawanna plant located near Buffalo constituted the input materials for the new mills. In 1967 a hot metal facilities program was announced for Burns Harbor that at its completion would make the plant fully integrated. Incorporated within the program were: 1. A new high performance 50" x 96" slabbing mill complete with a battery of soaking pits. 2. A two vessel Basic Oxygen Furnace Shop. 3. (1) battery of 6 meter high Coke Ovens with attendant coal handling facilities. 4. A 3800 feet long vessel loading & unloading dock. 5. The first conveyor belt fed Blast Furnace in the United States. 6. An extensive materials handling system for receiving, stocking and reclaiming from storage the raw materials for the Blast Furnace and Coke Ovens operation. The intent of this paper is to provide a detailed description of the functions and components of the materials handling system noted above.

Jan 1, 1970

By S. F. Willey

The difficulties encountered in justifying replacements for over-age mobile mine equipment at the Gay Mine are common to most mining operations. More critical management reviews, resulting from ever rising capital expenses, increased such difficulties. These increased difficulties are especially apparent to those who are primarily operators and are not statisticians, mathematicians, or computer oriented. The Gay Mine is located 17 miles east of the town of Fort Hall in southern Idaho. This open pit operation annually supplies the J. R. Simplot Company and the FMC Corporation with 1.5 MM - 2.0 MM tons of phosphate ore. Stripping ratios average approximately three bank cubic yards of waste per ton of ore mined. The mobile mine equipment fleet consists of ten 24 yard scrapers; twenty-one 30-50 ton end dump trucks; four 32 42 yard shovels; fifteen dozers in the D-8 and D-9 classes; and three road patrols. Equipment replacement is based on the results of evaluations made on individual units. Authorization of capital expenditures for equipment replacement is dependent upon a favorable profitability index (true rate of return on investment) plus a favorable payout time. The system is based on cash flows and requires the determination of (1) the net cash outflows in the form of capital expenses plus (2) the expected cash inflows resulting from reduced expenses and depreciation tax credits. After adjustments for taxes and the time value of money, the net amounts are used to calculate the required indices. The basic elements for the system related to the replacement of mobile mine equipment include: (1) the determination of dollar penalties to be expected from the continued use of aging equipment; (2) the selection of equipment that will provide the greatest return on the investment dollars; (3) the quantification of the expected savings; and (4) the calculations of the prescribed indices. Inadequacies inherent in previous evaluating methods led to the search for more

Jan 1, 1972

By W. Edwin Dill

For the mining industry, the Internal Revenue Code and regulations offer a range of choices in arriving at the allowable depletion. Each case is essentially unique. Two prerequisites can optimize these opportunities: communications between the mining company&apos;s tax specialists and its technical staff; and an understanding of IRS definitions. For the latter, a logical starting point is consideration of exploration and development, since they precede production and depletion is unallowable prior to production. Criteria for selecting engineering and accounting options for exploration and development indicate the necessity of interaction between these company functions to achieve the most favorable tax position.

Jan 1, 1982

By Jim Johnson

The purpose of this paper is to summarize and discuss a variety of site specific conditions which are typically evaluated as part of the engineering design process for heap leach pads, solution control ponds, and associated facilities. The following sections will focus primarily on the topographic, climatologic, hydrologic, and geotechnical evaluations critical to selection of heap leach sites, and selection of a preferred heap leach configuration or method. Other important considerations in the design of a heap leach project, including evaluation of ore properties and leachability, pregnant solution processing requirements, spent ore neutralization/disposal requirements, and other anticipated reclamation requirements are beyond the scope of this paper are not addressed in any detail.

Jan 1, 1998