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By M. Schultz

The cost of remediation often drives the selection of the preferred remedial alternative at hazardous waste sites. The use of probabilistic cost/risk analyses can aid in predicting costs of remedial alternatives. Three types of information are discussed in performing cost/risk analyses: (1) data on the quantity of contamination versus the contaminant concentration; (2) unit costs of remediation for the remedial alternatives; and (3) risk to contaminant concentration relationships. Cost/risk evaluations are performed on a site-by-site basis, to account for combined risks of different contaminants and differences in quantity to be remediated versus contaminant concentration. The cost/risk analysis produces a graph of risk versus cost for each of the remedial alternatives. These costs are then compared to facilitate selection of a preferred alternative. An example of comparison of alternatives is illustrated for a historic coal gasification site.

Jan 1, 1992

By Andrew Chegwidden, Tara Wilk

Construction of Shaft 17B-1, a part of The New York City water supply system, required an excavation of approximately 38 m (123 ft) through water-bearing overburden soil and more than 152 m (500 ft) of gneiss bedrock to make a connection to Water Tunnel No. 3. Ground freezing was the specified method to provide temporary earth support and ground water control for the overburden material. The ground freezing process relied on a supplemental geotechnical investigation and comprehensive laboratory testing of the frozen soil to evaluate the potential long-term creep behavior of the soil and the elimination of a temporary lining system. This paper describes that process as well as the drilling and installation methods of the ground freezing system. Additionally, the methodical system of excavation and insulation is discussed that permitted a safe and timely excavation followed by the installation of the permanent concrete liner.

Jun 13, 2023

By Richard A. Brown

The direct precipitation of uranium with hydrogen peroxide has been known since 1877. Commercial use of the process began in the 1960's. During 1967 the Bureau of Mines assisted the Climax Uranium Co., Grand Junction, Colorado in the development of a uranyl peroxide precipitation process to control a molybdenum impurity problem (1). Atlas Minerals, Moab, Utah has used hydrogen peroxide to control vanadium and sodium levels in their uranium concentrates since 1969 (2). Recently, the use of hydrogen peroxide by the uranium industry has grown, particularly since the increased demand for uranium has led to the processing of low grade ores. Impurities present in low grade ores can be concentrated with the uranium during milling and will substantially complicate the refining of uranium yellowcake concentrates. Consequently, commercial nuclear fuel processors have imposed stringent specifications and penalties to control these impurities. The ability to produce a pure uranium yellowcake can eliminate penalty or reprocessing costs. Hydrogen peroxide precipitation of uranium is specific and quantitative, producing a very high purity product.

Jan 1, 1980

By Rodrigo Peroni, Vitor Campos

Carajás is one of the largest open pit mines in the world. The mine is comprised by a haul road network more than 100 km long, where the need for good roads is paramount and determining of the truck performances. This work integrates, regarding the ultimate pit design, an approach to consider an economic value to an originally unfit material, assuming it has the appropriate characteristics for haul road construction, which sometimes lies over economic iron ore. This measure demonstrated an improvement in the utilization of resources and guarantee the necessary material to the haul road design and Mining Pads maintenance.

Jun 25, 2023

By W. G. Pariseau

This paper is concerned with the problem of calculating ground movement that occurs as a consequence of mining. Solution to this problem is straight forward in principle but rather complex in practice. The complexities of the problem arise from the ever present constraints of technology and economics. However, the identity of these constraints is often obscured by a faulty understanding of the fundamentals of the problem and a lack of appreciation of current computational capabilities and costs. As a consequence much time and effort are sometimes wasted on gathering information that is of little direct value to ground control programs while important input data are neglected. This paper therefore reviews the essentials of the process of formulating the ground movement problem. Emphasis is upon application to longwall mining, although much of the discussion applies to other mining methods as well. In many instances, the hardrock term stope could be substituted for longwall panel because the fundamentals of the problem are independent of the excavation dimensions and numerical values of rock properties. The latter affect the outcome of a calculation, of course, but not the underlying formulation. Only the major features of the problem are discussed in this brief review. The objective of the discussion is the generation of a reliable basis for developing a technically sound ground control strategy. Any rational ground control strategy must be consistent with basic physical laws. For example, under static conditions, equations of equilibrium must be satisfied. Operational, that is, tactical, details may vary widely with local conditions, but the basic approach must be based on physical laws. The alternative empirical route is intrinsically unreliable and unnecessary as well. Empirical descriptions of ground motion caused by mining including recent statistical curve fits to specialized data sets (for example, surface subsidence data) as well as antiquated "theories" of ground pressure and so forth, however dignified with mathematical formulas, are hardly worthy of the label "theory". Extrapolation of statistical data is always accompanied by rapidly diverging confidence limits, while empirical equations simply lack predictive capability under circumstances even slightly different from those of the original development. For example, applications of surface subsidence curves generated empirically in the United Kingdom to coal mines in the United States generally result in considerably greater subsidence and wider subsidence troughs than actually observed. Locally, empirical criteria for specific ground control actions may be made practical through trial and error, but such tactics are no basis for the development of a general ground control strategy. In this regard, it is worthwhile to recall the traditional scientific distinctions between speculation, hypothesis and law, between the empirical and the proven.

Jan 1, 1982

By S. Anderson

Advances in inexpensive computer automation led to the development and utilization of a computerized ore control system at Cyprus Coppers tone Gold Mine near Parker, Arizona. These new ore control practices improved accuracy, performance, and productivity of the ore control effort. An automated system for data collection, including bar coding of blast hole samples, laboratory analysis, data management, grade estimation, cut delineation, and ore zone stakeout, plays a major role in ore control practices. This is of particular interest because of the large amount of blast hole information being processed, analyzed, and reported daily.

Jan 1, 1991

By William P. Blacutt

This paper describes the strategy, the struggles, and the obstacles encountered during the last two years in the ongoing process to capitalize Vinto. The effort involves the offering of a vertically integrated business package composed of the tin and antimony smelters along with the two principal tin mines of the country. Capitalization: Bolivia's Innovative Approach for Privatization, the Vinto Case provides a summary of hard-earned lessons. These experiences can be success- fully implemented in other nations committed to transforming their state natural resource sector.

Jan 1, 1998

By Biswajit Samanta, Rahul Kumar, Pranjal Pathak

The Open Pit Mine Production Scheduling Problem (OPMPSP) is a complex optimization problem that seeks to determine the best sequence for extracting mineralized material from the ground in order to maximize the Net Present Value (NPV). This process must take into account various capacity constraints, such as mining rates, processing limits, stockpiling capacities, blending requirements, and precedence constraints, which dictate the order in which blocks can be extracted. Traditionally, the OPMPSP has been formulated as a mixed integer programming problem, employing binary and continuous variables to represent the extraction of each block. However, this approach has limitations, particularly when it comes to addressing the stockpiling issue. In response, some researchers have proposed mathematical models, which offer a more accurate representation of the problem but come with their own set of challenges. In this study, an alternative approach to tackle the OPMPSP with stockpiling by employing constraint programming (CP) is explored. The method was carefully tested on the Newman1 dataset from the well-known Minelib library. The results show that the CP-based model obtained a production schedule having about 2.69 % higher NPV than the NPV of the solution, which is recorded in the Minelib Library.

Jun 25, 2023

By R. Kealey, D. Huo, Q. Zhang, Y. A. Sari

Greenhouse gas (GHG) emissions from primary mineral and metal production account for ~10% of global GHG emissions. One of the main sources of GHG emissions in mining operations is fuel consumption by haul trucks. Given their size and carrying capacity, the fuel consumption of haul trucks can approach 250 liters per hour. An average of 30% of the idle time of the trucks is spent while waiting in the queue. Inefficient truck dispatch planning can waste resources, cause dilution and elevate GHG emissions. In this research, a machine learning based truck dispatch approach was developed to dynamically route the haul trucks based on the loaded material, the road traffic, the estimated wait time, and the maintenance needs of the trucks. The GHG reduction potential of this smart fleet management approach was estimated by calculating and comparing the related carbon emissions versus scenarios using traditional fleet allocation approaches. Results suggest that this dynamic fleet allocation approach can significantly reduce GHG emissions at mineral production sites by optimizing waiting times and the overall distance travelled while achieving the same production levels.

Mar 2, 2022

By D. J. Frey

While costs of most commodities and services have increased markedly over the past 25 years, the cost of electricity has steadily declined. One of the reasons for this price decline is the improved efficiencies of generating plants which is shown in Fig. 1. 1,2 Another reason for this is the decline in coal production costs. Efficiencies for the best plant increased from about 32 percent in 1540 to about 40 percent in 1962 and then decreased slightly to 38 percent in 1965. The increase in efficiency for all plants (US average) has been even more notable, progressing from less than 15 percent in 1940 to about 32 percent in 1965. The chief reason for the improved efficiency is the change in operating steam temperatures. These increased about 12 F per year until 1200 F was reached in 1962. At this high temperature excessive corrosion of super-heater and reheater tubes was experienced and steam temperatures were dropped back to 1050 F and even 1000 F in some cases. To successfully compete against other energy sources for generating electricity, this corrosion problem must be solved so that operation at higher temperatures and thus, increased efficiencies will be possible.

Jan 1, 1967

By J. J. Casey

This paper is one of a series of presentations organized by the Conference of American Society of Civil Engineers with the goal of making significant progress toward an equitable and effective allocation of risks in construction undertakings among the principal parties - owner, contractor and designer. The role I have been assigned is principally one of identification of risk while others will devote greater attention to the allocation of these risks and the contractual arrangements necessary to properly make these allocations. Construction projects are joint undertakings by parties who bring different skills and interests toward a common effort, much as this conference does. A project is not an adversary proceeding and does not benefit from establishment of an adversary mode, as our lawyer friends seek in the resolution of legal issues. Accordingly, I urge upon this Conference the adoption of two basic precepts and guidelines as the criteria for sharing of the risks inherent in construction undertakings toward achievement through mutual effort the common goal of a successful project completed in the shortest time and at the least overall cost. These precepts are: (1) that all risks are rightfully the owners unless transferred to or assumed by another party for a fair compensation; and (2) that the principle guideline in determining whether a risk should be so transferred should be whether the receiving party has both the competence to fairly assess the risk and the expertise necessary to control or minimize it. The sponsors of the conference have provided certain guidelines to the authors. There is, however, no constraint in expressing one's bias and I suspect that my contractor's outlook may be inherent in my comments. The guidelines have suggested that I indicate whether the risks identified are ones that can or should be shared or borne by one party alone. In doing so, I will attempt to follow the precepts I have recommended.

Jan 1, 1979

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

Despite several methods (empirical, statistical and machine-learning tools) to calculate blast-induced ground vibration, it is not easy to predict and simulate blast vibration precisely under varying blasting loads and strata conditions due to complications in the blasting procedure. In this study, field blast data were simulated in Ansys software using explicit dynamics, and ground vibrations for 20 single-hole blasts were monitored. The densities of emulsion explosives were in the range of 0.9 to 1.15 g/cm3. In the laboratory, rock properties were determined from rock samples collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and density of the emulsion explosive were also determined and used in numerical analysis to know the ground vibrations at specific points. The results of ground vibrations predicted by the model were validated using field data.

By Botond Beno, Dave Watson, Danny Read

The Hampton Roads Bridge-Tunnel (HRBT) Expansion widens the existing I-64 four-lane bridge-tunnel corridor to eight lanes through construction of two parallel tunnels, interstate widening, and bridge expansions. The design-build contract was awarded to Hampton Roads Connector Partners with HDR and Mott MacDonald retained as lead designers in a Design Joint Venture. This paper will highlight some of the e challenges related to the design of the twin bored tunnels from spaceproong, tunnel enabling wors, segmental lining design and durability considerations.

Jun 23, 2024

By John W. Tieman

The increasing magnitude of our nation's pollution problems seems to stem from two main factors: urbanization and technical advance. In 1920, less than half the country's 106 million people lived in cities. Forty years later, the urban population accounted for 70 percent of the nation's 179 million. It is predicted that by the end of the century, 95 percent of the U. S. population, estimated at 280 million, will live in urban areas. As these people live increasingly in city concentrations, their residues also concentrate. With technological advances to support the increasing population, the variety and quantity of goods that we use also increases. New materials and processes result in increases in pollutants, some of them new. The harmfulness of these pollutants is sometimes known, but sometimes only suspected. One pollutant of concern at the present time is sulfur dioxide, the product of combustion of sulfur-containing fuels. Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased. Although many state-of-the-art papers have deluged the literature during the past several years, the research going on in the area of sulfur oxides control is of such importance that periodic reviews are justified. It is the purpose of this paper, therefore, to again review the state-of-the-art, but this time from the stand-point of what is immediately commercially available

Jan 1, 1972

By W. D. Blackburn

If there is a single key to managing a mineral extraction company, it is the control of productivity. American labor costs, in general, tend to be in the range of 10%-15% of total costs. American coal mining labor costs, however, exhibit ranges of 30%-60% of total costs. Is it any wonder that the industry finds itself at a competitive disadvantage? When labor costs take as much as sixty cents of every dollar of revenue, there is little room for profitability. The American coal mining industry must set as a long range goal the reduction of labor costs to the 10%-15% range of total costs in order to be competitive.

Jan 1, 1986

By Emmanuel V. Manlapig

The variables involved in a complex process like flotation can be classified as follows: a. Disturbance variables - which are undesired properties of the process input which affect the value of the process output but which are not subject to adjustment. They are the result of changes in the properties of the feed, like changes in head grade, flow rate, fineness of grind, etc. b. Manipulated variables (sometimes referred to as process variables or control variables) -which are those that are adjusted - reagent addition, aeration, pulp level - in order to compensate for the disturbances in the properties of feed. c. Performance variables (sometimes referred to as controlled variables) -which are those whose values measure the performance of the process. They are properties of the process output such as grade and recovery. The function of a control system is to maintain the process performance equal to the control objective in spite of the disturbances by adjusting the manipulated variables. Attempts at developing automatic control systems for mineral processing operations date back to the thirties and in many of these attempts the results were not surprisingly poor and un-stable. The poor results brought indifference and suspicion towards automatic control on the part of operators and management. The reasons for the apparent failure of these attempts were two-fold: a. the lack of adequate understanding of the behavioural responses of the process from the control point of view, and b. the lack of reliable control instrumentation which could withstand the harsh environment in mineral dressing plants. Many operators had accepted the fact that control of mineral dressing could be best conducted manually. In the case of flotation circuits, control had been virtually based on the skill and experience of operators particularly their ability to identify and rectify poor flotation performance aided by results from the laboratory (chemical) analysis of regularly collected samples from strategic points in the circuit which are at best, hourly collected samples.

Jan 1, 1978

By Ralph E. Weeks

Utilization of true in situ technologies for mining copper in Arizona will involve a complex environmental permitting process. This process is a key factor in determining the feasibility, costs, and implementing time frames required for development of this innovative mining method. The regulatory structure in Arizona is presently changing due to enactment of the Environmental Quality Act (EQA) of 1986 and development of new aquifer protection rules and regulations. The Bureau of Mines has reviewed the comprehensive hydrogeologic characterization, ground water monitoring, mechanical integrity testing, well construction, contingency planning, and other regulatory elements that will serve as mechanisms to assure protection of ground water resources. The purpose of this paper is to inform the domestic copper industry of the significance of the new Arizona regulatory structure and its implications for prospective in situ operators.

Jan 1, 1988

By M. Javier

"Mining is the main activity that supports civilization. Actual mining presents contradictory concept to the health of the planet. Its business model is linear, fragmented and characterized by inefficiencies in the utilization of water, energy and mineral resources which generate waste and pollution. Before mining begins, it is critical to determine the vulnerability of the ecosystem and after mining, it is critical to determine the depletion of nature. Attending to these vital matters will require quantifying and measuring them. The purpose of this study is to provide and establish the metric to assess the performance and manage a sustainable future for our existence and that of our planet. This index is defined to measure and control Nature Friendly Sustainability (NFS) based on understanding nature. This index will determine the condition of nature constructed on the measurement of physical, chemical and biological equilibrium. Proposing a new mindset for mining design to satisfy nature’s needs would be to offer the same opportunities to future generations. Hence, sustainability is synonymous with equilibrium under a limited ecosystem. Nature is interconnected. Finally, this index of NFS is readable, standardized and relevant to keep nature’s needs in equilibrium. Establishing and NFS index is the next metric for humanity. INTRODUCTION There are a multitude of definitions of what sustainability is. Most of them are defined in terms of the corporate entity from which they emanate. The classical definition of management states that, “if we do not measure it, we cannot manage it.” Management of ecosystems is the definition of sustainability. Indicators of quantity and quality of sustainability are vital in order to create a metric for sustainability. These indicators will measure the depletion and degradation of nature as they occur through human intervention. The first step is to create a metric of sustainability to simplify its definition. The definition of sustainability is based on whether or not you consider nature to be finite or infinite, which is described in Nature Friendly Sustainability (NFS) [1]. The definition of NFS applies to any anthropogenic activity with an understanding of the equivalent activity in nature. That is to say, human activity with nature requires balance and equilibrium in order to be sustainable. The importance of this equilibrium is quantified in a set of metrics in order to establish measurement and acknowledge indicators for our dependence on nature. Sustainability is synonymous with equilibrium in any ecosystem that is limited and fragile. In the graph is the explanation of sustainability definition. See Graph 1"

Jan 1, 2017

By Robert M. Dreyer

Although lateritic deposits have long been a principal source of bauxite and are becoming an increasingly important source of nickel, the problems in the evaluation of such deposits are not generally understood. In the evaluation of lateritic bauxite and nickel deposits, there are many similarities, but there also. are significant differences. It has long been recognized that laterites with commercial concentrations of trivalent metals represent the ultimate in the intense leaching of tropical soils. Any factors which effect-the rate of soil leaching will effect the form of local lateritic concentrations. Although the most intense leaching generally occurs on somewhat elevated areas of gentle relief where there is a free downward flow of rain water, the- effect of local rock structures in effecting varia¬tions in soil metal concentrations has-not been well understood - primarily because the laterite forms a masking blanket over the rocks from which the laterites were derived. All of the-factors which facilitate downward movement of water may effect greater surficial concentrations of trivalent metals. Such features as zones of fracturing, zones of greater rock permeability, and areas of karst topography may, therefore, be responsible for greater leaching. The variations in rock structures and the vagaries of ground water flow pat¬terns impart, to the laterites, rapid lateral and vertical variations in thickness and metal concentrations. Because of such rapid

Jan 1, 1970

By Jörg Holzhäuser, Matthew Crow

An 18.5 km (12 mile) long tunnel is being driven by four Earth Pressure Balance Tunnel Boring Machines (EPB-TBMs) of 4.7 m (15.5 ft.) diameter through alluvial sand, gravel, silt and clay above and below the groundwater table in Los Angeles beneath buildings, railroads, freeways and the L.A. River. Continuous automatic data recording of TBM operation and field inspectors' records, accompanied by monitoring of 5,000 surface reference points and 268 borehole extensometers were used to obtain information. The paper explains the reason for selecting the method of EPB-tunneling to ensure stability of the tunnel and meeting of environmental requirements, and presents data collected to monitor and demonstrate the performance of the TBM sin the different ground conditions encountered.

Jan 1, 2003