Search Documents

By Y. J. Wang

The selection of a shaft size for ventilation purposes is a classic problem of concern to mining engineers. This presentation is concerned with the sizing of conventionally-sunk circular shafts with concrete or shotcrete linings. Costs of sinking shafts of three different depths (from 500 feet to 1000 feet) and six different diameters (from 14 feet to 24 feet) were obtained through questionnaires to shaft contractors. The primary objective of the economic model presented is the balancing of detailed annual capital and operating costs to achieve the minimum overall cost of the shaft installation over its life. The economic model is similar to previous analyses but treats several of the individual cost categories in an updated fashion. Included in the paper is a detailed analysis of the effects of varying power costs on optimal shaft size. Also included are a statistical analysis of current shaft costs and comments on the choice between shotcrete and concrete linings.

Jan 1, 1977

By L. M. Kocher, J. R. Heberger, J. P. Pollard, M. F. Nasarwanji

Injuries associated with hands and fingers are highly prevalent in mining and identifying factors associated with these injuries are critical in developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011–2017. Hand and finger injuries occur at a rate of 6.53 per 1,000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53%) followed by bone fractures/chips (26%). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals (pipe, wire, guards) and hand tools as the primary sources of hand and finger injury. Although information on glove use was limited, leather gloves were most often worn when an injury occurred. When worn, gloves were found to contribute to 20% of the injuries, indicating their potential to protect the hands, but also potentially put the hands at risk. Further research is necessary to determine performance requirements for gloves used in mining operations, specifically those offering cut and puncture resistance.

Mar 2, 2022

By S. Mafi

The Broken Aro project is associated with a 1910 abandoned underground mine complex that has been discharging aeid mine drainage from entries, seeps and springs. The Ohio Department of Natural Resources(ODNR), R&F Coal Company (R&F) and American Electric Power (AEP) are involved with this unique project that will remine the abandoned underground complex and install a mine seal constructed of fixated flue gas desulfurization (FGD) material. The goal of the project is to eliminate or reduce the acid mine drainage that is discharging into the watershed. This paper discusses remining, installation of the FGD mine seal, government financed reclamation projects and future application to active and abandoned mining sites.

Jan 1, 1998

By J. L. Carr

On average, one to two fatalities occur every year when a miner is struck or pinned by a continuous mining machine (CMM). Proximity detection systems offer an effective means to prevent these types of injuries and fatalities by sensing the presence of a miner and automatically disabling machine motion. The Mine Safety and Health Administration (MSHA) is expected to finalize a regulation that would require the use of proximity detection systems on all CMMs. Approximately one-fourth of all CMMs in use in the United States are already equipped with such a system. The use of these systems will save lives, not only by automatically preventing accidents but also by acting as a tool for educating miners and reinforcing safe work practices. Researchers at the Office of Mine Safety and Health Research (OMSHR) have conducted a series of field evaluations to quantify the performance of these systems in an underground coal environment. These field evaluations measured the distance at which the warning and stop zones were activated. The technology provided consistent activation of the warning and stop zones under many of the conditions tested. However, some performance inconsistencies were observed which present opportunities to improve the reliability of proximity detection system technology. Some of the notable variables that caused significant changes in performance and should be considered in the design, implementation, and use of proximity detection systems include interaction with the trailing cable, performance changes during tramming, and orientation of the miner-worn component.

Feb 23, 2014

The reduced need for traditionally trained and educated personnel in the mining industry is systemic to the changing mining industry. Our universities and other training institutions are doing just fine meeting the traditional skill needs required by the industry. But are the skill needs going to be the same in the near future? The answer may be NO!! Mining is changing: increased liabilities and costs of environmental and safety issues; lower grades of minerals in traditional mining activities; the advent of new bio-chemical processes and robotic equipment as more productive and economic alternatives; and, larger more sophisticated and automatic equipment. Engineering is more specific, accurate, precise and expensive. Measurement is more thorough and timely of progress, production, costs, and productivity. And we will be engaging in more undersea mining, possibly space bases processing, less human interaction, and more remote control of events than was ever thought possible in the past. This paper presents several of the systemic changes that are presently and will continue to change the face of mining. It will identify area where education and management will have to address these changes.

Jan 1, 2011

By Roe-Hoan Yoon, Kaiwu Huang

Derjaguin and Dukhin (1961) were the first to develop a model for bubble-particle interaction in flotation from first principles by considering the surface forces in wetting (or flotation) films. The model predicted that the energy barriers to bubble-particle attachment arise from the ζ-potentials of fine particles, which corroborates well with an earlier work of Fuerstenau (1957) reported for the flotation of quartz using dodecyl ammonium acetate (DAA) as collector. In the present work, a series of surface force measurements have been conducted by accurately monitoring the changes in bubble curvature during bubble-silica surface interactions. The curvature changes are then used to determine the capillary force, which is the sum of the hydrodynamic and surface forces. By subtracting the former that can also be determined from the curvature changes, one obtains the surface forces (or disjoining pressure). The results obtained as functions of pH and collector concentrations show that control of the ζ-potentials of bubbles relative to those of the silica surfaces is critical for maximizing the negative disjoining pressure, which is conducive to promoting bubble-particle attachment in flotation.

By James N. White

Completion of the Hall Street Coal Transfer Terminal in St. Louis marks the beginning of a major shift in the movement of coal to the power generating stations of the Midwest and South Central regions of the United States. The location of the terminal is significant. The 10 million ton- per-year facility is the first high capacity rail-to-barge transfer terminal to be built on the western shore of the Mississippi. This terminal and others to follow will link the massive coal fields of the West with the high coal consuming markets adjacent to the 25,000-mile Inland Waterway System.

Jan 1, 1979

By R. Brown, A. J. S. Spearing, M. Treinen, M. Theisinger

The mining and use of coal creates a significant amount of waste material that needs to be safely disposed of. It is likely that in the medium term, the Environmental Protection Agency (EPA) in the U.S. will categorize all such products as a new category – special waste. This would make the materials subject to many of the requirements for handling toxic waste, which will complicate the disposal of such products and significantly increase the disposal costs. Underground disposal would, therefore, seem to be the obvious solution, especially if the placed material can have low or no permeability, so that water table pollution does not present a serious long-term issue after placement. Significant additional advantages could be derived from this backfilling, including the reduction or elimination of surface subsidence, increased extraction, reduced surface waste disposal footprint and the elimination of explosion-proof seals in worked out areas. The research using a specific coal waste product as a typical example proved that the method of placing the backfill at a high density with low permeability is technically viable, but it must be made more cost effective and the other potential benefits quantified and costed in order to present a true comparison.

Jan 1, 2010

By N. T. Rempe

Proper use of natural resources is multiple use. Underground space resulting from mineral extraction offers opportunities for deep geologic waste disposal (DGWD) which can solve many environmental problems. U.S. government projects plan to use specially mined excavations to dispose of radiotoxic and mixed waste. DGWD takes careful planning, technology transfer, and true partnership between waste generators and mine/repository operators. Using the experience, accumulated by domestic projects in preparation, and by foreign repositories in operation, U.S. mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1996

By Wern-ping N. Chen

Pressure tunnel includes water-supply tunnels and tunnels for hydroelectrical power plants. Their design principles are different from those of water/wastewater/conveyance and transportation tunnels. Though theoretical pressure tunnel design guidelines exist, a comprehensive guide to summarize these guidelines to facilitate the planning and design of a pressure tunnel program is lacking. The purpose of this paper is to fulfill this need. It first provides key pressure tunnel design concepts in hard rock environment; then, it illustrates associated final lining design principles, including the design of un-reinforced concrete lining, steel lining, and reinforced concrete lining. Design diagrams and a flowchart for the reinforced concrete lining design are provided.

Dec 1, 2022

"The paper treats the spatial aspect of mine sequence optimization. This aspect is revealed in the context of determination of the optimum number of cutbacks of an open pit mine. Cutback mining is a dominating method currently in base\precious metal mining and it is based on a pseudo-economic discretization of the pit space by using advanced pit design algorithms. The result of the implementation of such approach of pit design is the generation of pit shells, which need to be grouped into an optimum number of cutbacks for maximization of the project value. A mathematical solution of this problem is developed with the utilization of a combinatorial analysis. The solution provides a multi-variant investigation of the optimum mine sequence with the implementation of an author’s method for production scheduling optimization, which uses the Net Present Value as a criterion for assessing the economic efficiency of mine sequencing. A case study is provided for the conditions of a hypothetical open pit gold mine to illustrate the applicability of the approach. The results obtained reveal the complex nature of the variation of the Net Present Value as a function of the cutback geometry. INTRODUCTION The mine sequence optimization in open pit mining is a procedure that predetermines the efficiency of the production scheduling optimization. From a technological standpoint, the mine sequence optimization deals with two aspects – spatial and time. Each of them plays a tremendously important role in searching for the optimum solution of the open pit design problem. Original results on the time aspect of mine sequence optimization are published by Halatchev [2002]. They reveal a wide range of the Net Present Value (NPV) variation for a multi-variant arrangement of mine sequence over time and using a fixed geometry of the cutbacks, which determines the economic potential of a single open pit mine from a deterministic standpoint. The results show a range of NPV variation up to 30% depending on the stripping ratio of the mine. The effect of this variation is mainly due to the implementation of the mine planning principle of waste deferment in the scheduling optimization and using all theoretically possible variants of mine sequence arrangement by the inclusion of the bench sequences over the Life-Of-Mine (LOM) in the production process."

Jan 1, 2015

By L. Xinguang

Shandong MinMetals Corporation, a state-owned import and export organization located in the city of Qingdao, Shandong Province, China, was opened in 1954, with the mission of marketing metal products and industrial raw material in oversea areas for hard currency to support the modernization project of the country as well as the province. The management officers are appointed by the provincial government, and report to the Foreign Trade Department of Shandong Province. Meanwhile, the company also receives guidance from MinMetals head office in Beijing, the capital city of China. The head office does not own and control any provincial MinMetals organizations, but merely coordinate business among provinces.

Jan 1, 1990

By D. L. Langhans

Platinum-group metal (PGM) converter matte from the Stillwater Complex, MT, was subjected to chemical and biological leaching in an effort to upgrade the matte by decreasing the Cu and Ni content. Copper and NL extractions were optimized in a two-stage chemical leach. Atmospheric pressure sulfuric acid leaching removed over 90 pct of the Ni and Fe in the first stage, while 95 to 98 pct of the Cu was removed is the second stage using an acidified cupric chloride leach. This two-stage leach, followed by an elemental sulfur removal step, decreased the weight of the matte by 90 pct. The combined Cu and Ni content was reduced from 65 pct to less than 20 pct, while the PGM content was increased from less than 2 pct to 26 pct. Biological oxidation using Thiobacillus ferrooxidans also proved to be an effective method for removing Cu and Ni. Over 90 pct of the sulfide was oxidized and 99 pct of the Cu and Ni were solubilized, leading to a 60 pct reduction of sample mass during the 17 week bio-oxidation of the Stillwater converter matte. The final residue, after removal of jarosite that accumulated during bio-oxidation, contained less than 3 pct combined Cu and Ni and 6 pct MM.

Jan 1, 1993

By Teena Redhorse, David Tsztoo, Anthony Yu

"Since ancient times, storing and conveying water via underground water systems and tunnels has been touted for its strategic advantages. Underground cisterns and tunnels assured protection of essential fresh water supplies from man made contamination and especially from enemies who would gain an advantage by disrupting an adversary’s water supply in a siege. Modern day engineers do not usually specify tunnels for reasons of avoiding deliberate contamination or siege — however, they are just as enamored with the idea of building tunnels for water conveyances.Such was the case for the San Francisco Public Utilities Commission (SFPUC). The SFPUC provides drinking water to 2.6 million residential, commercial and industrial customers in the San Francisco Bay Area. The SFPUC’s water system includes 257 km (160 miles) of transmission pipelines and tunnels from the SFPUC’s largest reservoir, the Hetch Hetchy Reservoir inside Yosemite National Park, to San Francisco. About 129 km (80 miles) of the system consist of tunnels. A 30-km (19-mile) section of the tunnel network, called the Mountain Tunnel, was thought to be at risk of a catastrophic failure in its concrete-lined section of 18 km (11 miles). For much of the project planning process, a new replacement tunnel was presumed to be required according to the tunnel planners.Originally constructed between 1917 and 1925, the Mountain Tunnel has been in continuous service since 1925. The 30-km (19-mile) tunnel is located downstream of the Hetch Hetchy Reservoir water source in Yosemite National Park, between the Early Intake and Priest Reservoir (Fig. 1). Approximately 18 km (11 miles) of the tunnel is lined with unreinforced concrete. Though the condition of the tunnel was being monitored through water sampling and periodic inspections, there was growing concern that the tunnel lining was at risk of a partial collapse that could interrupt water delivery for up to nine months. The SFPUC was faced with a decision to construct a new bypass tunnel to replace the lined section of the Mountain Tunnel or to rehabilitate the existing tunnel."

Jan 6, 2018

By Daryl R. Tweeton

The Bureau of Mines measured the geochemical changes as H2S04 was used for in situ uranium leaching by Rocky Mountain Energy Company near Casper, Wyoming. Cores and ground water were analyzed before leaching. Water samples were taken from observation wells located between injection and production wells as the leach solution was brought up to full strength in several steps. Measurements were made of pH, Eh, temperature, conductivity, total dissolved solids, dissolved oxygen, HC03, U, V, Na, K, Ca, Mg, SO4, C1, Mo, Mn, Fe, Al, Si, F, P, As, and Se. The data were gathered to assist in geochemical modeling of leaching and to study the potential environmental effects of acid leaching. Environmental considerations appear favorable. For example, the concentration of Se, a toxic element often found in uranium deposits, stayed below the EPA standard for drinking water.

Jan 1, 1979

By A. K. Clarke

In any treatment process that requires a coarse feed material to be reduced to a fine size by crushing and/or grinding it must be determined whether a wet or dry comminution system should be utilized. All factors must be evaluated in reaching the decision. Among these factors are: 1) Ecology and Plant Environment: Unfortunately in many instances the decision on wet or dry is based on prejudice resulting from an unnecessary fear of dust. The writers submit that this fear, although once justified, is no longer valid because technology and equipment is now available to collect dust to meet any standard. When dry grinding is used it is very often possible to discard a portion of the waste product in a dry state. This will decrease the size of the tailing pond required. As pollution control standards increase it becomes increasingly difficult to clean up water from tailing ponds. 2) Operating Costs: Steel wear is often five or more times greater in wet grinding than in dry grinding. This is mainly due to corrosion. The evaluation of the economics of dry grinding must of course include the air system and dust collection; similarly in a wet grinding plant related pumping and material handling costs should be included. Pumping costs are often overlooked. This assumes water is made to flow for nothing. Pumping can account for 20 percent of the power consumption in the grinding plant. Large scale comparative tests were conducted in a wet and dry commercial plant in 1970. The same ore was used for both tests. With all factors included in both plants the dry system showed lower horsepower per ton.

Jan 1, 1971

A new analytical approach for characterizing and improving the performance of ball milling is presented. Individual ball mill circuit design and operating variables can be related to overall circuit performance through two distinct parameters for classification and breakage. The ball mill circuit functional performance equation is presented. Applications in the industrial plant and in the research field are discussed.

Jan 1, 1990

By David I. Smith, Kenneth Arnold, Bryan Aweh, Vincent Falkowsk, Brian Lakin, Andy Fer

Nassau County, New York, is undertaking several projects to improve the water quality in the Western Bays of Long Island. A major step forward will be the completion of the Bay Park Conveyance Project, which will divert most treated effluent away from the Western Bays to an existing ocean outfall at the Cedar Creek Water Pollution Control Plant. The ongoing works include 3.6 miles of microtunneling, 7 miles of sliplining, 14 shafts, and a 75 MGD pump station. This paper provides an overview of the design and an update on construction progress through December 2022. The project is a collaborative effort between Nassau County, New York State Department of Environmental Conservation, the design-builder, and various consultants.

Jun 13, 2023

By Walter Steiner, Claus Becker

INTRODUCTION General Switzerland is a densely populated country in the heart of Europe. With its total surface of 41.300 km2 and a population of 6,8 million in 1986 the average population density is 163 capita / km2. The population density is lower than in Germany (245 capita/ km2) or the Netherlands (355 capita/km2). The USA have a population density of 26 capita/ km 2. However, sixty percent of the Swiss surface is covered by the Alps and another ten percent by the Jura mountains the remaining thirty percent of the surface is covered by the Swiss plateau where the majority of the population lives. The population in the inhabitated areas is thus substantially higher and may possibly reach those in major metropolitain areas. Due to the high population density in Europe in general and Switzerland in particular future traffic demands cannot be fulfilled sole by car or plane. Environmental and land-use constraints lead to the third option for growing transportation needs: High-speed rail (Bovy, 1990). Switzerland has developed its own approach to promote public transportation and in particular rail transportation: "Rail 2000" (Stalder, 1990). The system "Rail 2000" is based on a series of hubs distributed over Switzerland where easy connections can be made.

Jan 1, 1991

By S. K. Singh, J. Shepherd

"Feather edging"- a major source of injury and fatal accidents in Australia, South Africa and USA, refers to a phenomenon where the roof, at the goaf edge, falls as a thin wafer of rock often suddenly, over-riding conventional timber breakerlines. It may run down and affect adversely a working bord at distances of 15 metres or more from the goaf edge. Feather edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a mine trial where a concentrated row of fully grouted bolts were able to resist the feather edging in the first comprehensive, monitored trial in an Australian pillar ('total') extraction coal mine.

Jan 1, 1999