Search Documents

By Owen Kingman

This paper discusses grade control of ore mined at Tennessee Copper Company. Mineral zoning and the influence of mineral zoning on production grade are discussed and illustrated. In order to make this most understandable we will first briefly examine the flow sheet at Tennessee Copper to indicate the path followed by the raw material toward its various products. Then we will discuss some of the characteristics of the ore, specifically the distribution or zoning of the minerals in the ore which cause some of the grade control problems. Finally we Will discuss same of the steps that are taken to combat these problems. The flow sheet is illustrated as plate 1. The mined ore is allied to obtain 3 usable products: Copper concentrate, iron concentrate and zinc concentrate. Copper is found in the mineral chalcopyrite, CuFeS2. The Copper concentrate from the mill contains about 20% copper. These concentrates are smelter in reverberatory furnace and Pierce-Smith converter to blister copper containing 99.2% copper. Some metal is cast into 360 lb. pigs and shipped to the refinery. Some is made into shot copper and used locally to make copper sulfate. Copper sulfate is marketed from Copperhill principally in fungicides.

Jan 1, 1960

By T. A. Gray

There are several potential large-volume uses for coal ash in mining-related applications that could be environmentally and economically beneficial to mining companies. Actual usage, however, may be constrained by regulations or by perceptions of coal ash and the potential uses. To identify currently allowed uses and to assess constraints to coal ash use in the eastern coal fields, questionnaires were sent to state coal mining agencies to determine their policies on coal ash utilization and to mining companies to solicit their viewpoints on coal ash utilization. Identifying and understanding the constraints will allow for the development of a coordinated and consistent approach to remove or reduce these constraints and possibly allow for increased utilization of coal ash by the mining industry. This paper summarizes the findings of our investigation.

Jan 1, 1995

By Richard Engelmann

The mining industry, in particular the coal industry, has experienced the implementation of some major environmental regulatory programs during the past two decades. Over the coming decade the coal industry will probably experience only "fine tuning" of the regulatory programs they now operate under. The rest of the indus- try, however, appears to be on the verge of coming under a major new regulatory effort by the Environmental Protection Agency. Litigation and resulting court decisions will be the main force driving further changes in the SHCRA (Surface Mine Control and Reclamation Act) regulatory program. These changes are anticipated to be minor in compar- ison to earlier changes. EPA, however, is preparing a regulatory program which may carry as much impact to the rest of the mining industry as SNRA was to coal. Details of this program have yet to be worked out. Changes in the way EPAts Clean Air Program is applied to mining could also significantly impact the mining industry.

Jan 1, 1989

By J. A. Herbst, A. E. Oblad, Y. C. Lo

The major cost in comminution is energy consumption, which can be as high as 50% of the operating cost. Improvements in plant operations have resulted in up to a 15% reduction in energy usage (kw-hr/t). These improvements have been made through the optimization of grinding efficiency and the use of expert model-based control systems. Optimization involves the determination of the levels of the critical-operating conditions that result in the most efficient breakage of ore in the mill. These optimal levels are identified through plant/laboratory test work and through computer simulation using advanced process models. Model-based expert control achieves the maximum performance from the grinding circuit by identifying the characteristics of the ore in the mill with an optimal on-line estimator. Using this information, the control system dynamically determines the operating point that will yield the optimal performance. Two industrial applications of grinding-circuit optimization and model-based control are presented to demonstrate the power of this new technology.

Jan 1, 1997

By V. N. Kolesnikov

The gold-silver deposits of the northern Primorye region are located in the eastern part of the East Sikhote-Alin volcanic belt, where the belt overlaps the Kema island-arc terrain of the Aptian-Albian age. There have been four deposits and numerous mineralization points found in the NE-trending Kema metallogenic belt that is about 1000 km long and 100 km wide. The known mineralization is of epithermal type, controlled by faults, and concentrated in quartz, quartz-fluorite-adularia, and, less commonly, sulfide-quartz vein systems hosted by the Upper Cretaceous-Lower Tertiary volcanic rocks. The vein systems extend for hundreds meters along strike, varying from tens centimeters to 50-60 meters in width. They are surrounded by wide zones of low-temperature hydrothermal alteration containing some gold-silver mineralization for which the commercial value was not studied during the early exploration. The ore bodies contain from 1 to 50-80 ppm of Au and from 1 to 1000 ppm of Ag. Gold is native, associated with quartz, and represented by particles from tens of microns to 1 mm in size. Silver occurs in native form as a constituent of argentite, pyrargyrite, stephanite, and other sulfosalts. The test work carried out for three vein systems 20 years ago showed that gold might be easily and almost completely recovered from the ore by cyanide treatment. The paper describes the geology and mineralogy of the deposits, Salut and Primorskoye, that are the most studied properties of the Kema belt. It also presents the data available on disseminated gold-silver mineralization in stockworks, altered explosive breccias, and wide zones of low-temperature hydrothermal alteration. This mineralization should be explored for possible exploitation as large open-pit, heap-leach deposits.

Jan 1, 1998

By Johanna I. Wong, R. John Caulfield, Victor S. Romero

The existing Hetch Hetchy water system, owned and operated by the San Francisco Public Utilities Commission (SFPUC), serves 2.4 million people within the San Francisco Bay Area. The system has existing 1920s-era pipelines crossing under the Bay that are vulnerable to seismic damage from the nearby San Andreas and Hayward fault zones. The SFPUC plans to replace the pipelines with the first TBM-driven tunnel underneath the San Francisco Bay. The tunnel will be constructed using an Earth Pressure Balance machine. The new tunnel will pass under environmentally sensitive habitats and will be approximately eight kilometers (five miles) long with no intermediate shafts. The project challenges will include tunneling through a prominent buried bedrock ridge that transects the alignment and through soft soils under the Bay. Seismic performance criteria include maintaining service flows after a large earthquake on one of the active faults in close proximity to the project site.

Jan 1, 2007

By G. E. Slagel

On August 3, 1987, a hearing was held by the House Subcommittee on Energy and the Environment to commemorate the tenth anniversary of the Surface Mining Control and Reclamation Act (SMCRA). Four panels of environmental/citizen group representatives went before the Subcommittee to report on the state of affairs (from their perspective) of the coal industry and the Office of Surface Mining, Reclamation and Enforcement (OSMRE) As expected, these groups had little positive news to report and continued to focus on glaring deficiencies within the surface mining program. They indicated that gross abuse of SMCRA has continued over the past ten years and the states have performed poorly. Congressman Udall's opening comments perhaps best characterized the mood of the group with his statement that "The Act has not accomplished what I or the people of the coalfields had hoped." and " ? a segment of the coal industry has continued in its bitter and implacable opposition to the most basic of environmental controls."

Jan 1, 1988

By G. T. Homce

Most electric motor predictive maintenance methods have drawbacks that limit their effectiveness in the mining environment. The U.S. Bureau of Mines is developing an alternative approach to detect winding insulation breakdown in advance of complete motor failure. In order to evaluate the analysis algorithms necessary for this approach, the USBM has designed and installed a system to monitor 120 electric motors in a coal preparation plant. The computer-based experimental system continuously gathers, stores, and analyzes electrical parameters for each motor. The results are then correlated to data from conventional motor-maintenance methods and in-service failures to determine if the analysis algorithms can detect signs of insulation deterioration and impending failure. This paper describes system design and implementation. At this writing, however, installation is still underway, and field data analysis results are not yet available.

Jan 1, 1994

By Robin G. Adams

The market prices received by producers of internationally traded commodity metals have been, and continue to be remarkably volatile and unpredictable compared with most other traded goods and services. This volatility results in an erratic financial performance on the part of producing companies, disruptive and often inflationary cost changes for consumers, unreliable tax revenues and export earnings for host governments and severe social and economic pressures on local, sometimes remote, communities which are dependent on the activity in question. Generally speaking, price volatility appears to be associated with the inability of the metal producing side of the industry to regulate the volume of supply in a manner that is consistent with metal demand, which in turn reflects broad macroeconomic and industrial developments around the world. This statement does not purport to apply to all metals or to all instances of volatility of course. Price movements may occur as a result of pure speculation or even illegal manipulation of the commodity markets. Embargoes, boycotts and other politically induced supply changes may contribute. Threatened or actual strikes also cause artificial swings in sales volumes and prices. How- ever, most of these developments are of a short-term nature. Yet metals price cycles may last for several years, as demonstrated by the extended copper price trough from 1981 to 1986. This paper deals with price volatility which reflects long-term economic cycles and the adaptive processes that exist within the industry in response to such cycles. Special emphasis is placed on the role of forecasts and forecasters in these processes. It should be said at the outset that this reflects the personal experience of one forecaster working in private sector commercial consulting practices that are independent of producers, consumers and host governments. However, the experience does cover the entire period since 1973 and has involved working with a substantial majority of the major companies that supply high volume commodity metals. By way of background it should be stated that the post-1973 world economy has provided a challenging environment for forecasters. One cannot be precise about the forecasting record of either industry insiders or outside consultants, financial analysts and academic forecasters because comprehensive records have not been kept, or if they have the results are too embarrassing to be published. Institutions such as the World Bank have published forecasts of the prices of major commodities on a regular basis and these have, presumably, had some influence on financing decisions in the industry. This record along with our own experience and numerous discussions with metal producers, major consumers and host governments permits certain generalizations to be made. The most important of these is that during the early 1980s. from about 1980 through 1985/6, the forecasters system- atically and substantially over- estimated metal prices. While some fore- casters did correctly anticipate a recession in the early 1980s and some consequential decline in prices, the magnitude and duration of the decline was far greater than anyone foresaw. This systematic forecasting "failure" appears to have occurred independently of the forecasting methodology employed. Moreover, its extent cannot be explained by obvious factors such as incorrect macroeconomic assumptions. There appears to have been some kind of structural change in the world mining and metals industry over this period

Jan 1, 1989

By R. T. Swinderman

This paper discusses a series of tests designed to help answer the age old question: ?How much does the belt cleaner wear my belt?? The experimental set up and test method are described. The main variables are: belt cleaner blade materials, cleaning pressures, cleaning angles, belt speeds, and belt top cover grade. The bulk material used is a standard test-grade silica sand. The measured results include: blade mass loss, belt mass loss, and cleaning efficiency.

Jan 1, 2010

By V. V. Ershov

Mining geometrical graphic documentation is employed on a large scale in designing and planning of mining operations at all the stages of exploitation. Mining geometrical modelling of mineral grade distribution presents an independent type of mathematical (graphic) modelling. The idea of functional relationship between geological indices being observed, and spicier coordinates is the basis of traditional mining geometrical modelling. Graphic presentation of three independent variables P =f (x,y,z) is confined to obtaining the series of two independent variables functions. Independent variables are presented as topographic surfaces corresponding to plane cross-sections of a deposit. During exploitation of certain parts of a deposit the most reliable geological information is obtained, characterizing regularities of ore distribution in the entrails. This information is, though, not taken into account in goemetrization of the new areas. In this connection dynamic modelling of deposits in the process of exploitation is necessary, i.e. geometrization of the deposits should be dynamic.

Jan 1, 1986

By Laurindo De Salles Leal Filho, Arthur Pinto Chaves

The Serrana Process was developed in the 60's to concentrate an igneous low grade phosphate/carbonate ore using tall oil as a collector and corn starch as a modifier in alkaline medium. Nowadays, although tall oil has already been substituted by a new amphoteric synthetic collector, starch hasn't been substituted yet. This study is an attempt towards understanding the role played by corn starch in this specific system. By means of bench scale flotation test, it was observed that corn starch was capable of promoting the flotation of apatite, phlogopite and dolomite. No effect over calcite was observed. The best efficiency of separation apatite/gangue minerals was yielded at the concentration ranges of 17 to 20 mg/l of starch and 13 to 17 mg/l of tall oil. The starch concentration showed a strong influence over the characteristics of the froth produced by the flotation tests, mainly over the volume of the froth and its mineralization.

Jan 1, 1993

By K. Nuttall, S. Vijayan, A. J. Meinyk, R. D. Singh

For conventional applications, there is limited demand for rare earth elements as well as yttrium and scandium. But the emergence of new high technology applications such as supermagnets, lasers, and superconductors should result in significant demand for some of these elements. This article examines the anticipated applications and demands for rare earth elements over the next decade. It also looks at the implications on the use of available resources. In the context of a growing demand, process methods are reviewed for the recovery of rare earth elements from conventional and unconventional resources. And the article also discusses the challenges facing the mining industry in meeting this opportunity. Reserves and reserve base The rare earths (RE) are a homogeneous group of metallic elements occupying the area from lanthanum to lutetium in group IIIB of the periodic table. Yttrium and scandium are also included with the rare earths because of their chemical similarities and common existence in nature. These 17 elements and their atomic numbers are shown in Table 1. The rare earths are widely distributed in low concentrations throughout the earth's crust (Hedrick, 1985). They occur in many rock formations including basalts, granites, shales, and silicate rocks at concentrations of 10 - 300 ug/g. They also occur in more than 160 discrete minerals. Most of these are rare, but may contain as much as 60% rare earth oxides (REO). More than 95% of the REO occurs in three minerals: monazite and bastnasite for the light rare earths and xenotime for yttrium and the heavy rare earths. Apatite and multiple-oxide minerals, such as euxenite and loparite, are also commercial sources of the lanthanides and yt-trium. Rare earths do not occur in nature in the elemental state. And, except for scandium, they do not occur in minerals as individual compounds. Bastnasite and monazite are the two major minerals used commercially to supply most of the rare earths (Hedrick, 1985). Bastnasite is a key raw material source for the cerium subgroup elements. The largest known bastnasite deposit occurs with iron ore minerals in China. The second largest deposit is situated in California. Typical rock analyses of the fluorocarbonate mineral bastnasite deposit in California show about 15% bastnasite. The REO content of that is about 50%. Monazite is present in beach sands in many parts of the world. This includes India, Brazil, Australia, South Africa, the

Jan 1, 1989

By W. E. Lytle

Environmental permitting is a critical component for joint-venture projects located in the Commonwealth of Independent States (CIS). This paper presents the basic CIS regulatory environmental requirements for permitting of a hypothetical mining source and emphasizes air permitting. Topics which will be covered include: the Expertiza process, air pollution quantification, data requirements, and air pollution modeling protocol. A comparison will be made between permitting requirements for air pollution sources in the United States and a CIS country, Kazakstan.

Jan 1, 1998

By James C. Gilliand

Leo-potpourri, was selected as the title to this paper for several reasons. First, it is a fascinating word--not looking like it sounds or sounding like it looks. It also allows for a great degree of flexibility in designing a presentation around it. Further, it has become popular to use this eco hyphen something pattern. We hear of eco-mania, eco-hysteria and the like. Lastly, in this era of intense environmental concern, two of the principle elements on which the integrity of our efforts must be equated are ecology and economics. Accordingly, the term "Eco-potpourris" allows me to roam at will through the great number of considerations that make up this environmental issue. Whereas only a few years ago the subject of environment and environmental control had low visibility with the public, today it competes as the focus of attention with the many other popular social issues of our time. The program content here at this meeting, for example, is liberally represented by papers dealing with one or more aspects of environmental concern. If one would look at the 1964 program, in contrast, I would expect that no more than possibly one or two papers covered this subject and even then that those papers dealt principally with the environmental aspect of occupational health. It is gratifying that the program at this meeting demonstrates a serious awareness to a broad spectrum of environmental concerns. It would be a mistake, of course, to believe that this clamor for a quality environment is a "flash in the pan" that will soon subside. The general public has been thoroughly aroused and even frightened into

Jan 1, 1972

By R. R. Fernández

The Newmont roasting plant in Carlin, Nevada, commenced operating in December 1994. Over the years, refractory ores and pyrite concentrates from different gold deposits constituted the feed to the facilities. Historical plant performance indicated that the roasting temperature was the main variable affecting the structural characteristics of the calcine, which in turn affected the recovery of gold by cyanidation. Gold recovery as a function of roaster temperature has been closely monitored since October 2000. The original design temperature was 550° C. Lower roaster temperatures of around 500° C resulted in a gold recovery increase of more than six percent. This increase was directly related to an increase of the surface area of the calcine. The implementation of an ?intelligent? process control system helped significantly in achieving steady low roasting temperatures, thus obtaining high gold recoveries of 92 to 93 percent. Under these conditions, several roasting campaigns with high-arsenic-containing ores were conducted, which resulted in a significant decrease in gold recovery. The reduced gold recovery was caused by the loss of surface area (e.g., porosity) of the calcine as the arsenic content of the roaster feed increased.

Jan 1, 2010

By T. B. Szwilski

ISO 14000 series are voluntary international standards that address environmental management system standards, environmental auditing, environmental labeling, environmental performance evaluation, and life-cycle assessment. An environmental management system (EMS) is a facet of an organization's structure that addresses the immediate and long-term impact of a company's products, services, and processes on the environment. Many companies in the United States are taking a cautious wait-and-see approach before embracing ISO 14000. A few mining companies are reviewing the standards and using them as guidelines. The paper outlines the status, possible benefits to the mining industry, and options available to a company wanting to become involved in the ISO 14000 standards.

Jan 1, 1997

By Edgar A. Scholz

The purpose of this paper is to make a comparative cost analysis of domestic and foreign exploration projects which developed into mines during the 1960-1974 time period. A total of 18 mining companies, American and Canadian, were approached to solicit cost data on domestic and foreign exploration projects which developed into mines. Only 20 percent of the companies to which questionnaires were sent made data available. Several companies answered negatively, informing us that they would have difficulty in attempting to sort our costs. Some companies were usable to release cost details. It is comforting, however, to realize that some of the non-contributing companies expressed eagerness to hear the findings of this paper. Inasmuch as the data available on exploration expenditures is, in some cases, somewhat uncertain and that no two mining companies follow the same system of cost allocations, the results obtained in this analysis should he interpreted as trends of a general character.

Jan 1, 1976

By John Greenhalgh, Benoit De Rivaz

"1.INTRODUCTIONThis paper is based on the Lee Tunnel project, which is part of the Thames Water’s Tideway Project.The client Thames Water has employed a Joint Venture of Morgan Sindall/Vinci Grand Projets and Bachy Soletanche to undertake the design and construction of the project under the management of CH2M Hill at a value in excess of £635 million ($990 million). The 3 main elements of the tunnel project are the permanent lining to the shafts, the precast segmental lining, and the secondary tunnel lining. All 3 are reinforced with different types of Dramix steel wire fibers and each element will be described in this paper. This paper will explain the basic structural design of FRC (Fiber reinforced concrete) based on the post cracking residual strength and will describe all the steps of this project, the testing program realized to support innovative design and the main technical learning point. 2.BASIC CONCEPT OF STRUCTURAL DESIGN OF FRCStructural design of FRC elements is based on the post-cracking residual strength provided by fiberreinforcement. Other cases, like early age crack-control or fire resistance, are considered non-structural use of FRC. For structural use, a minimum mechanical performance of FRC must be guaranteed. Fibers can be used to improve the behavior at SLS (Service Limit State) since they can reduce crack spacing and crack width, thereby improving durability and they can be used to improve the behavior at ULS (Ultimate Limit State) where they can partially or totally substitute conventional reinforcement in most conditions. In the design process, the definition of the performance expected from the material is a key factor and the mix-design of the material has to be optimized for the required structural performance.2.1 Testing Method In order to ascertain the structural requirements requested for the FRC segments, preliminary testing on samples will be required and the effectiveness of the proposed solution will also be assured by the testing of full scale specimens. Structural design of FRC elements is based on the post-cracking residual strength provided by fiber reinforcement. For structural use, a minimum mechanical performance of FRC must be guaranteed. Nominal values of the material properties can be determined by performing a 3-point bending test on a notched beam according to EN14651 (figure 1) or by performing the ASTM C1609 beam test:"

Jan 1, 2016

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely, and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once the analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at the power plants. A quality assurance program can also help the mine deliver a consistent product to the electric utility's power plants. The importance of the three major tenants for a good quality assurance program: accuracy, timeliness and consistency, are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994