Search Documents

By P. Maraboutis

Extractive industry (mining and quarrying operations), as other industrial activities, is subject to environment protection laws, regulation and standards such as the Environmental Impact Assessment directive, Natura 2000, Habitats & Birds directive, Water Framework directive etc The European Commission (EC) is aim to strengthen the EU environmental legislation to improve the (environmental and human) safety of mining activities. The mineral processing and the management of the mining waste will be covered by the new amendment of the Seveso II Directive, by a Best Available Techniques reference document (BREF) describing the Best Available Techniques of mining waste management and a new directive on the mining waste management. At the same time initiatives as the environmental liability, the energy taxation for environmental reasons and the natural resources management policy, which will have a positive impact on the protection of the environment, will affect the extractive industry operation procedures.

Jan 1, 2002

By R. L. Urie, L. Burdzinski

Non-operational mine facilities are subject to placement on the EPA's National Priority List (Superfund). Once a mine site is undergoing investigation and/or remediation, MSHA regulations for health and safety may no longer be applicable. This paper addresses the changes in the applicable and relevant standards that apply to health and safety and public health related to site contaminants. The implementation of health and safety plans, and the development of public health risk assessments are described. Examples are presented from Superfund activities at the Eagle Mine, near Minturn, Colorado; the Anaconda Smelter near Mill Creek, Montana; California Gulch near Leadville, Colorado; and Bunker Hill, Idaho.

Jan 1, 1991

By G. Banini

A plug-flow model is described for the reactor mass balance of a typical AARL gold elution process. The model is in the form of a hyperbolic differential equation and was transformed using the method of characteristics. The transformed model was then solved simultaneously with models dependent on intraparticle surface diffusion and film transfer parameters. The solution was found to represent the experimental data for a modified form of the AARL elution. Correlation between the experimental conditions and the film transfer parameters estimated by the model are also presented.

Jan 1, 1998

By R. P. King, M. K. McCarter, K. S. Free

Mine plans typically consider the profits and costs associated with extracting and processing minerals into marketable products. Interrelationships between mine and mill costs are often overlooked during the process of mine plan optimization. A simple and quick method for predicting milling costs for a given block would improve the planning process, especially if the procedure could be incorporated as part of routine ore grade analysis of drill core or cuttings. Incorporating milling costs as part of the mine planning process could improve overall optimization of the mine/mill combination. A method developed by the Utah Comminution Center (UCC) at the University of Utah provides a possible answer to the need for quick and reliable grinding cost estimation (King et al., 1996). Using results from single-particle impact tests, a work index, called the Utah Load Cell Work Index (ULCWI), is calculated. The potential for routine use of the new method is explored by comparing ULCWI values with corresponding Bond Work Index (BWI) values for eight mineral materials (Free, 2000).

Jan 1, 2004

By W. F. Kane

Underground geologic mapping is an extremely important aspect of any on- going ground control plan. However, the actual use of data derived from such a program is difficult and often leads to subjective analysis. In this regard, computer software has been developed that utilizes a statistical determination of unstable ground conditions based on geomechanical and operational data and collected by mine personnel on a mine-wide, or regional basis. Categorical variables, such as faulting or joint frequency, are selected from local experience to form the framework of a representative data base. Statistical comparisons between the selected variables and a particular ground control problem are conducted and correlations subsequently made. The probability of encountering unstable conditions in virgin areas is assessed as information from these regions is gathered. This data can be derived from surface mapping, cores, and/or geophysical logs. As mining progresses, new data is merged with the existing data base to form a more comprehensive and extensive unit. The advantages of this approach and the acquisition and maintainence of a large data base include the more accurate representation of existing mining conditions, increased confidence in analyzing future problem areas, and elimination of the difficulties which arise when using ground control theories derived for other, often very different, locales.

Jan 1, 1986

By Robert F. Reeves, Stephens A. Avary

Introduction People, systems, methods, and organization make up maintenance productivity. Methods promote efficiency in operations, systems ensure consistency and continuity, and organization maintains direction and control. The common denominator in these techniques, though, is people. Management systems can be technically correct, but fail to work because management systems do not work by themselves - people make them work. Therefore, the foundation for mine maintenance productivity must begin with the people involved. Traditionally, the emphasis placed on mine maintenance, as opposed to production, is not proportional to the impact that maintenance has on a mining operation. The performance and productivity of mine maintenance substantially affects the operating costs, revenues, and profits of the mine. The mining industry has recently experienced a period of economic depression. While it has created financial problems in all segments of the industry, it has caused the industry to focus on the need for improved productivity. Mining companies that have made investments in productivity during this period will have a competitive edge during the recovery, and mine maintenance may be the best place to put that investment. Future lost production and maintenance cost problems can be avoided if mine management has the foresight to seize the opportunities that now exist. Background Technological improvements over the last 30 years have been dramatic in the industry. Before these changes, mining equipment was not very sophisticated. So maintenance needs were not very sophisticated. Maintenance people were not required to have any formal training in mechanical or electrical skills. At many mines there was no formal maintenance organization. The mechanic was a part of the section crew and received direction from the face boss. Mine maintenance was not a function, it was a task. Technological change in mining came about in response to an expanding economy and greater demand for mined products. The past 20 years brought about a change in the kind of individual needed to mine ore and coal, and an even greater change in the person needed to maintain equipment. Equipment went from mechanical and pneumatic to complicated electrical and hydraulic. Maintenance progressed from being a task to being a function. Types of Mechanics Mine maintenance workers can be grouped into three categories based on experience: mechanics with more than 20 years, five- to 10-years, and less then five years. These groupings have influenced mine maintenance productivity. The 20-plus mechanic has been the foundation of the maintenance force. He had no formal training and his skills were acquired on the job. As new equipment was introduced, he learned to repair it by trial and error. Not all of what he learned was correct. Personal initiative and conscientiousness are characteristics of this group. They have experienced the bad times and the good, and appreciate the opportunity to work. The five- to 10-year group worked with the older, more experienced mechanics to acquire maintenance skills. These mechanics came in during industry boom times, and many progressed quickly by being in the right place at the right time. Many in this group have difficulty with diagnostic trouble-shooting, and depend on changing out parts to identify problems. This group is generally more mobile and less apt to have a strong work ethic. Mechanics with about five years experience have vocational training, some formal education or basic skills training. Like the five- to 10-year group, these miners are mobile and tend to move readily to satisfy their changing needs. These two younger groups are less apt to feel any loyalty to the employer or obligation to be productive. Their attitudes and abilities reflect the influence of their general age groups, and has a definite impact on mining productivity. Past Requirements In the 1960s, the basic requirements for a maintenance supervisor was that he be a top mechanic, get along well with the men, and be a hustler and improviser. He learned the details of new equipment as repairs were needed. Oftentimes, this individual would be the only person on the property with the ability to read prints, use diagnostic testing equipment, and troubleshoot using an analytical approach. This approach to maintenance is sufficient when the equipment design is reasonably uncomplicated. Management Changes As technology progressed, organized labor gained strength, government regulation increased, and the job of supervising and managing people had to change. The environment has changed and

Jan 11, 1983

By Donn A. Calder, Wayne C. Henderson

The Calmet Process for extraction and recovery of gold and silver from concentrates and high:grade ores has been a commercial reality for over two years. During that time period, almost seventy-five different concentrate (or ore) types have been processed in approximately 200 separate lots (a total of almost 2000 short tons). During commercial operation of the process at the plant in Fountain, Colorado, recovery of gold and silver into <lore' has averaged almost 93% for gold (range 81-98%) and over 90% for silver (range 76-97%) based on a fire assay target and calculated head values.

Jan 1, 1998

By James R. Arnold

Over the past few years several commercial wetting agents and drying aids have been tested in the lab and in the plant at Gold Fields Mining&apos;s operations at Mesquite and Ortiz. The major goal was to increase recovery with these surfactants by improving the permeability of the pad and increasing the rate of penetration through the rock.

Jan 1, 1988

By E. A. Rychkun

Introduction Minicomputers have been gaining acceptance in mining. Low cost interactive processing and plotting can now be controlled by geologists or engineers needing rapid solutions and specialized mining software in formats that allow noncomputer personnel to readily interact with computer processes. User-oriented programs maximize the use of interactive display features and graphics, as shown by the HP9845 minicomputer, a unit with portability, processing power, graphics capabilities, capacity, and peripherals such as plotters, digitizers, disk drives, and printers. Application Coal exploration projects require that much effort be spent determining coal volumes within trial pit limits. This determines a prospect&apos;s viability and potential. Adapting volume calculations to a computer has been limited, since it was difficult to create reasonable representations of complex coal seam geometry with a digital process. So many of the simple mechanical procedures needed to produce pit reserves are still performed manually by geologists and engineers. But with new minicomputers and their interactive graphics, it is now practical to accurately model complex structures without tedious calculations. GEOSEM (Geomin Seam Oriented Exploration System) is a computer system designed to analyze coal prospects. The system shows how a coal prospect, with complex geology, can be quickly analyzed, modeled, displayed, and evaluated for mineable reserves. Its interactive graphics allow rapid visual presentation of data, high-speed tabular reports, and precision plotting. The system is most effective when used by a geologist or engineer who selects the required operations and specifies relevant parameters via screen and keyboard interaction. Rolling Hills The Rolling Hills prospect represents a typical Rocky Mountain coal deposit. Enough geological interpretation has been done to show a complex system of block faulting with coal seams following synclines of stratified lithologies. With the completion of initial drill hole exploration, questions arose concerning coal volumes and strip ratios involved with various pit limits. Quality information had been gathered on the coal intercepts. It was decided that coal vol¬umes and pit designs were of prime importance. The objective was to enter and display data, create a computer model based on interpretation, develop pit designs, compute seam/ waste volumes, and report various contents. The project, begun by entering data in the GEOSEM system, was completed in several days. Data Entry For modeling, the prime information was seam identity and drill hole intercept. Other information-rock type, Btu rating, and percent of ash, sulfur, and moisture-was also available. It, too, was entered into the data base through the computer keyboard and then reported, verified, and corrected. Various reports can be produced, according to user specified sort parameters. For example, from an analysis of available data, only 14 intercepts could be found with Btu value greater than 8000 and sulfur content less than 0.4%. The sort option can also be used prior to entry into the analysis routines. Data Analysis Though the objective was to create a seam model and compute reserves, it became necessary to project quality information into unsampled areas. Statistical analysis was then war-ranted. A typical analysis correlated the lack of relationship between percentage of ash and Btu. Although histograms were also produced, these typified a lack of samples and "ragged" distributions. A geostatistical analysis was also applied, showing the results of computing a 2-D variogram on the largest coal seam. Results showed an average range of 18 m, with a poorly defined variogram. Data Display and Drafting Scaled plans and sections were required so seam locations could be compared to hand drawn interpretations and drill coordinates verified. At the same time, topography could be interpolated from collar elevations to determine whether surface control points were needed for better definition. In addition, a new set of 50 final-scale drawings were required, showing new drilling information. By using the computer screen as a "scratch pad" device, various sections were displayed and then plotted on a drum plotter at the desired scale for overlay on original sections. Both lithology and seam name were plotted for the five main sections. Since the coal seams were striking north-south, sec-

Jan 11, 1981

By Lennart Mukka

LKAB has been mining iron ore in northern Sweden for about 100 years and now enters the next century with a major new investment in Kiruna. The under- ground projects involve construction of a new main haulage level, a new mining system and a new ventilation system. This paper describes the Ventilation Procject from the investigation stage through to construction.

Jan 1, 1995

By John V. Beall

A completed feasibility study executed by an independent agency can benefit a company in two ways. Inside the organization, it verifies the project staffs ideas and their concept of the facility. Outside the company, it can be utilized to obtain equity partners, debt financing, and other forms of credit. It is advisable to bring in a project execution contractor for the feasibility study. A project execution contractor is able to work with engineers to develop the project concept, process flowsheet, and best utilization of the site. By getting an early start on understanding a company&apos;s policies and working methods, a project execution contractor saves the company money since it does not have to go through the educational buildup twice. The contractor is a specialist in putting together a bankable document that can be taken to a financing source. It answers all the agency requirements on the first pass. In addition, the contractor can advise an owner on likely financing sources since he works on the worldwide market every day. A less obvious advantage of including the contractor in the study and predevelopment buildup stages is the importance of coordinating finance and technical input. The financing source influences equipment specifications, procurement, logistics, project schedule, cash flow, and liquidity. There are many surprises in store for any manager of a large international project involving worldwide financing and purchasing. The job does not have to be made more difficult by bringing in a contractor after all predevelopment steps are taken. The contractor can still work if the predevelopment steps have been done, even if he does not agree with them. But early contractor involvement is the preferable solution.

Jan 10, 1980

By Richard L. Nielsen

Early Models In 1906, Daniel Jackling demonstrated that relatively low-grade disseminated copper deposits could be mined profitably using mass mining technology. The ensuing years saw a gradual increase in activity aimed at defining ore targets for large reserves of disseminated supergene enriched copper ores. Prominent organizations, such as Calumet and Hecla, Phelps Dodge, and Asarco, established teams of geologists. They focused on interpreting oxidized and leached outcrops over supergene chalcocite ore bodies. Techniques to evaluate oxidized cappings and predict the presence of underlying supergene chalcocite enrichment ores were developed and put to practical use by the late 1920s and early 1930s (Locke, 1926; Blanchard 1939, 1968). Oxidized capping evaluation centered on recognizing oxidation products derived from the various sulfide minerals found in disseminated deposits. Chalcopyrite, for example, oxidizes to a characteristic reddish pitch limonite that exhibits characteristic boxworks. Chalcocite is recognized by earthy, powdery, indigenous, hematite-rich limonite. Pyrite weathers to characteristic cavities and yellowish jarositic limonites. Evaluation of cappings is a systematic effort of noting and estimating the preoxidation sulfide mineral content and copper grade in an oxidized outcrop using mineral composition and morphology of oxidation products. Several complications were noted early in this technology&apos;s development. For example, the associated pyrite content of protore greatly influences mobility of copper and iron during oxidation. High-pyrite disseminated sulfide assemblages, upon oxidation, mobilize iron as well as copper. This results in oxidized rock with many leached cavities, poorly developed boxworks, and poorly developed indigenous limonites. This effect was noted and used in a general way to identify possible development of supergene chalcocite. Indeed, strongly leached outcrops could be present over enriched ore. A second complication is the manner in which associated gangue minerals influence the products of sulfide oxidation. Reactive gangue minerals, such as carbonates, neutralize acids formed by sulfide oxidation. Thus, copper cannot be moved from oxidized outcrops. Relatively nonreactive gangue, such as quartz-sericite-altered schist or porphyry, neutralizes supergene acid very slowly. This allows copper to move out of the oxidized outcrop. Recognizing these features was closely allied to an early understanding of the processes involved in oxidation supergene enrichment of disseminated ores. Field observations and mineralogic mapping of oxidized cappings were important in discovering many important porphyry copper ore bodies during the 1920s. These include Silver Bell, Miami-Inspiration, and Morenci in Arizona; Tyrone, NM; and Ely, NV. Capping interpretation like-wise led to discoveries at Mineral Park and Esperanza in Arizona during the exploration surge that accompanied high copper prices in the 1950s. In the 1960s, Kennecott research geologists refined and quantified some aspects of oxide capping appraisal (Anderson, 1982). The ratio of jarosite plus hematite to the total limonite assemblage was shown to be proportional to amount of copper leached from the oxidized outcrop. Thus, if the limonite assemblege in an oxidized capping consists of 40% goethite, 20% jarosite, and 40% hematite, 60% of the original copper is leached. The amount of copper remaining in the capping, together with the limonite mineralogy, can then be used to estimate original copper grade in the outcrop, amount of leaching, and chalcocite enrichment grade (in feet/% copper) in the underlying supergene chalcocite zone (Anderson, 1982). Evaluation of oxidized cappings and prediction of chalcocite blanket ore targets were successfully used in the western US and South America through the 1950s. Discovery of new porphyry copper provinces in other regions during the 1950s and 1960s, however, underscored some limitations of capping evaluation technology. Porphyry copper systems in Australia generally oxidize and weather to hematitic cappings. Presumably, the semiarid monsoon environment and the long time that the sulfide systems have been exposed to oxidation on that continent lead to development of relatively stable hematite. It is now recognized that jarosite and goethite persist metastably in the limonite assemblage in all areas once sulfide oxidation is complete and acid generation ceases (Brown, 1971). The assemblage eventually converts to hematite. But, climatic conditions in arid southwest US allows metastable limonites to persist for a long time, thus providing information on former sulfide assemblages. Another problem occurs when applying capping evaluation techniques in extremely humid re-

Jan 12, 1984

By L. Micale

In May of 1986, the Arizona Legislature passed comprehensive environ-mental legislation called the Environmental Quality Act (the Act). The Act focuses on ground water protection and addresses drinking water quality, aquifer protection standards, requirements to apply technology to reduce discharges, and a state Superfund program.

Jan 1, 1988

By E. F. Divers

Adequate ventilation of coal mine working faces is the most important technique for controlling respirable dust and methane. Choosing the right technique presents some tough questions. US Bureau of Mines research has shown that to control respirable dust, you must contain the dust near the face, keeping rollback (turbulence) to a minimum. For methane, the most effective approach has been to use a blowing brattice, or tubing, and to create turbulence and disperse the face methane, allowing it to pass over the machine and into the return. It is immediately apparent that the two approaches may counteract one another, thus complicating the decision as to which system may be best for a given situation. At present. Bureau research has developed two successful machine-mounted face ventilation systems to meet these different needs and allow deeper cutting. The fan- powered dust scrubber is designed to control dust primarily associated with blowing face ventilation systems. The spray- fan controls methane on exhaust-ventilated sections.

Jan 1, 1987

By Jeffery H. Stricklin

Jim Walter Resources operates five underground coal mines with longwall faces in operation in four of the mines. Due to high air velocities (1000-1200 fpm) needed for methane control together with the friability of the coal, dust control on JWR longwalls offers unique challenges. We have tested many innovative measures to reduce respirable dust concentrations on longwalls with varying degrees of success. These measures include the "shearer clearer" system, different drum water spray configurations, sprays on the longwall belt, stageloader and crusher sprays, wetting agents in the spray water system, and homotropal ventilation. Water infusion of deactivated horizontal methane drainage holes in longwall panels is now being evaluated. A study was completed in November 1986 where water was infused into two horizontal de-gas holes. Personal gravimetric samplers were used to measure respirable dust concentrations and showed a significant reduction in the infused zone. A more in depth study will be conducted. This paper will describe the dust control measures presently used on JWR longwalls, give the results of past studies, and discuss new methods proposed to control longwall dust.

Jan 1, 1987

By Gail B. Knight

INTRODUCTION In May 1984, The Canadian Pacific Railway awarded to the Joint Venture of Foundation of Canada, Ltd. of Toronto, Atlas Construction Co. of Montreal, and S. A. Healy Co. of Chicago the contract for the construction of 27,000 ft of tunnel starting from the east portal. Selkirk contractors, the Joint Venture of Foundation, Atlas and Healy, which had successfully completed for CPR in 1983 the construction of both portal structures for this tunnel, studied several different alternative proposals before presenting its bid pooling each individual company&apos;s technical resources and experiences. (Foundation had just completed in association with other companies a similar tunnel project in British Columbia, and the S. A. Healy Co. could provide its experience of more than 40 miles of tunnels excavated by full face boring machines.) Among the alternatives investigated there was a fully circular tunnel to be excavated by a 30 ft diameter TBM, a full section drill and shoot proposal, and a mixed alternative, the "key hole" proposal, consisting of a TBM driven circular top heading followed by benching to design size. Technical, geological and economical considerations determined the alternative that was eventually proposed to CPR. HISTORICAL NOTES The tunnel construction parallels an existing tunnel through the Selkirk mountains that was excavated in 1885. In order to reduce the grade to 1% on the heavily loaded west bound trains, the new tunnel was at a lower elevation and lengthened to almost 9 miles. GEOTECHNICAL INFORMATION CP Rail site investigations began in 1978. The surface rocks in the tunnel construction area are metamorphosed Cambrian and Pre-Cambrian sediments; the underlying formation contains fine and coarse grained rocks presenting different degrees of metamorphism. The

Jan 1, 1987

By Sibley C. Burnett

Early attempts to apply superconductivity to the beneficiation of kaolin required very large refrigerators to remove the heat generated during rapid charging and discharging of the magnet. In the early 1990&apos;s, Advanced Cryo Magnetics, Inc. developed and patented methods to reduce this pulsed heating by a factor of fifteen. Small, helium refrigerators and cryo-coolers are now used. Along with savings in electric power, superconductivity allows operation at higher magnetic fields and greatly improves separation process efficiency. New designs offer enormous reductions in weight, size and capital cost as compared to older copper magnets. Application of this technology to minerals other than kaolin is emerging.

Jan 1, 1999

By Key Rosebrook, Jennifer Laggan, Ashley Rivera

Significant quantities of waste rock at abandoned uranium mine (AUM) sites in the western United States require removal from steep slopes exceeding 45 degrees in remote locations. This prevents the use of traditional excavation equipment and poses significant challenges for safe, effective material removal. A pilot study was conducted using a spider excavator to demonstrate the feasibility of removing waste rock and transporting it to areas where conventional equipment could be employed. The spider excavator was evaluated for its effectiveness in excavation, material movement and control, container usage, dust mitigation, and ensuring human health and environmental safety. The study established constructability and engineering parameters for implementing spider excavators in these challenging environments. Key outcomes include the preservation of existing vegetation, improved waste movement control, and enhanced safety measures for workers, nearby residents, and the environment.

Feb 1, 2025

By James A. Pappas, Francis L. Fong, Tracy K. Lundin

The impact of environmental regulations on the quality of tunnel groundwater discharges is examined in this paper. Tunnel contractors usually depend on specialty contractors or outside consultants to deal with this issue without carefully examining their activities to minimize the production of contaminants. This approach may not be adequate given increasingly more restrictive environmental requirements. This paper surveys the general practice of the tunneling industry and attempts to identify sources of contaminants which may affect the total suspended solids, oil and grease content, and pH of the discharges. Strategies for treating the discharges are included. Field data and observations from several tunneling projects are also presented.

Jan 1, 1995

By Juan L. Yarmuch, Gonzalo Sepulveda

Medium- and short-term mine planning holds immense significance in optimizing production and resource utilization. It serves as a vital link between the long-term strategic plans and the day-to-day operational activities of a mine. In this context, a mathematical formulation is proposed to incorporate mining width constraints into the production scheduling process, aiming to maximize the net present value (NPV) of the schedule while ensuring enough room for the operation of mining equipment.

Jul 1, 2024