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A kinetic model for leaching of various metals with different lixiviants in a batch system has been developed. Material balances for reactants and products at the solid/liquid interface were formulated and solutions to these balances were obtained in view of practical conditions. Special emphasis has been given to examine mixed controlled reaction systems where both heterogenous reaction and mass transfer play important role on the overall rate expression. The resulting kinetic expressions for either powder or rotating disc are discussed in light of experimental findings for various metals. Examples of the metal dissolution systems considered in this study include cobalt, nickel, copper and gold in acid, cyanide or ammoniacal solutions.

Jan 1, 1992

By Michael V. Wolski, Ryan O. McCarter, Kenneth A. Johnson

"The Central Subway is Phase 2 of the San Francisco Municipal Transportation Agency’s (SFMTA) Third Street Light Rail project and will extend the existing Phase 1 initial operating segment from its current connection to the Embarcadero line at Fourth and King streets along Fourth Street to Market Street, under the Bay Area Rapid Transit (BART) and Muni Metro tunnels and then north beneath Stockton Street to Chinatown (Fig. 1).Total new track to be constructed as part of the Phase 2 work consists of approximately 734 m (2,410 ft) of surface track and 2,636 m (8,650 ft) of tunnels. The tunnels were constructed as twin, singletrack bores by two tunnel boring machines (TBMs) (Johnson, 2014) moving north from the southern end of the launch box under the I 80 freeway between Bryant and Harrison streets. North of Chinatown Station the TBMs continued another approximately 683 m (2,240 ft) to a retrieval shaft near Columbus Ave. at Washington Square. The project also includes five cross passages to connect the two tunnels, and three underground stations (the Yerba Buena/ Moscone Station, Union Square/Market Street Station and Chinatown Station.)Excavation of the twin tunnels was performed with two TBMs, with both TBMs driving northward from the launch box. TBM excavation was performed such that the location of the machines was staggered to separate the active excavation faces by a minimum of 91 m (300 ft) between headings. This minimum separation was maintained until the first TBM arrived at the retrieval shaft plug, at which time the separation requirement was relaxed.Excavation began with the “southbound” (SB) tunnel which will ultimately accommodate the southbound TBM light rail trains followed by the second TBM in the “northbound” (NB) tunnel. With the completion of the drives in June 2014, cross passage excavation then began and was completed in April 2015. Overall, construction of the Central Subway tunnels was a success considering the nature and complexity of the project. Additional details of the completion of the Central Subway tunnels are presented in another paper from the RETC 2015 conference (Leong et al., 2015)."

Jan 1, 2015

By S. W. Mao

Hydrologic and economic criteria figure in many obvious ways in water resources development, but they are rarely linked quantitatively, and most of the applications are pertinent only to the case-in-point. In the preparation of the Regional Plan for the massive program of ground water development in the Punjab, situations have arisen where the choice among two or more alternatives was made by analyzing the economic implications of critical hydrologic parameters. Two of these situations which are of more-or-less general interest are described herein. The first involves basic development policy -- whether ground water development should be based on the demand of the economy, or the conservation concept of safe-yield. The analysis demonstrated that mining of ground water is clearly indicated for areas where alternative supplies are unavailable. The second problem involves integrating hydrologic data into an economic model to determine optimum well design, From an analysis of all pertinent factors, a simple nomograph was derived which can be used to determine well specifications on-site during construction. The nomograph can be modified for use in any alluvial terrain.

Jan 1, 1967

By R. P. Fischer

Traditionally, molybdenum and vanadium have been used chiefly as alloy metals in steel. They impart similar characteristics to most steels, and to some extent one can be substituted for the other. In the United States during the 1950's the production of steel increased about 5 percent, and the reported consumption of both of these alloy metals in steel increased some 40 percent. In Europe during the 1950's the production of steel in¬creased nearly 100 percent. Data on the actual consumption of these alloy metals in European steels are not available, but production and trade records show that the European supplies of molybdenum increased about 150 percent and those of vanadium about 350 percent during the 1950's. If most of the molybdenum supplies in Europe are being added to steel, as seems likely, then the European steel industry has nearly caught up with the United State in the rate of consumption of molybdenum in steel. The vanadium supplies, on the other hand, are puzzling--unless Europe is adding mach more vanadium to steel than is done in the United States, it seems reasonable to assume that other uses are consuming moderately large quantities of this metal or that appreciable amounts of it are being transshipped from Europe. To the extent that a changing volume of supply signifies a changing pattern of use, the increased demand for molybdenum and vanadium in Europe should be of interest to domestic producers and consumers of these metals.

Jan 1, 1964

By R. Spring

Artificial intelligence, and especially expert systems, are currently receiving considerable attention. Of interest to the control engineer is the utilization of these tools for real-time process control applications. To evaluate this technology, a real-time expert control system was implemented in one of the grinding circuits at Brenda Mines Ltd. The performance of this micro computer based expert system compared satisfactorily to the proven supervisory control system currently in use. The study confirmed the expectations that expert systems have potential for real-time, supervisory control of mineral processing operations.

Jan 1, 1989

By Phil Jones

"Dilution — planned and unplanned – remains a significant cost impairment in the mining process. A series of trials were held over a sixmonth period in fiscal year 2018 (FY18) that established the cost-benefit of new technology as it applies to the alignment accuracy of production drilling rigs in underground mining, thus confirming its ability to limit drilling as one of the causes of dilution. The trials identified three underlying factors affecting drilling accuracy, measurable by blast-hole deviation surveys of planned versus actual toe data. These were rig alignment error, collar location change/ error and in-hole deviation.The trials involved a comparison of existing rig setup processes and technology, with the new technology (Minnovare’s Production Optimizer system). The trials were undertaken in the same environment: the Cracow gold mine, an operating underground mine. The comparison first revealed the extent to which rig alignment impacts blast-hole deviation. Secondly, the new technology was proven to limit rig alignment error, thereby reducing average blast-hole deviation and increasing the number of holes drilled within tolerance by 160 percent.The increased accuracy reduced stope dilution by reducing over-break of subgrade ore. The new technology was implemented at Cracow during the latter half of 2018. Despite utilizing the new technology for just six months of the year, the mine recorded a 5 percent overall reduction in dilution for the full year compared to the previous year (FY17); from 22 percent down to 17 percent (a net decrease of 22.7 percent). Mine management attribute a significant proportion of this reduction to the new technology, along with sequencing and planning improvements. This opinion is backed by detailed stope reconciliation data taken during the trial from 28 stopes — representing 20 percent of the total tonnes mined during FY18. The data identified that stopes drilled using the new technology recorded 62.6 percent less average dilution."

May 1, 2019

By James E. Lawver

The agriculture industry has made great strides during the past decade to increase agriculture yields through increased use of fertilizers. Increased use of fertilizers may prevent or at least delay mass starvation due to the alarming increase in world population. Phosphate was added to soil as a plant nutrient in the forms of calcined bones at least 2 000 years ago, (1) and man has used phosphate minerals as a source of fertilizers in one form or another for at least 100 years. During 1977 the world produced about 116 million metric tons of phosphate rock, with about 86% used for fertilizers and another 4% for animal feed supplements. More than three-fourths of the total production comes from the United States, Morocco, and the Soviet Union. From a mineral beneficiation point of view, the major sources of phosphate rock and the methods of beneficiation can be classified as follows. Marine deposits not containing appreciable carbonate minerals, marine deposits requiring a francolite carbonate mineral separation, igneous deposits not containing appreciable carbonate minerals, and igneous deposits, requiring an apatite carbonate mineral separation.

Jan 1, 1978

By Juan J. Monsalve, AMAN SONI, ALEX PFREUNDSCHUH, Nino Ripepi

Ground control failures are one of the main causes of accidents in the underground stone mining industry. Some of the fundamental tools for rockfall hazard identification are related to rock mass characterization and geotechnical discontinuity mapping. Recent technological advances in these methods are related to remote sensing techniques and point cloud processing software for automated discontinuity mapping. Remote sensing techniques, such as LiDAR and photogrammetry, generate multimillion point clouds with millimetric precision, capturing the structure of the rock mass. The automated point cloud processing tools offer alternative algorithm-based methods to characterize and map these discontinuities. However, their applicability is constrained by multiple factors such as site specific conditions of the rock mass and the parameters used within the mapping algorithms. This paper evaluates the performance of automated discontinuity extraction software compared with manual virtual discontinuity mapping. Sampling windows from laser-scanned sections in an underground limestone mine are defined and mapped using discontinuity set extractor (DSE). Results from the virtual discontinuity software are compared with manually extracted fractures from I-Site based on reviewing orientation, trace length, spacing, number of extracted discontinuities, and processing time. The analysis determined that the automated mapping algorithm was able to identify the same discontinuity sets that had been manually mapped. The automated mapping software mapped an excessive amount of smaller fractures, which caused the comparison of both mapping techniques to be unsuccessful in terms of trace length and spacing.

Mar 19, 2021

By John J. Reed

Since the beginnings of, the human struggle for survival and improvement, mining has been one of the basic endeavors of life. Until relatively recent times it was classed as an art. Now we are at work trying to, raise mining to the level of an engineering science where it belongs if we are to prosper. It should be self-evident that this goal can be attained only through industrial progress: based on education and research. It is true that our industry, left to itself, will develop a few new ideas and techniques through the years. However, we mining' engineers are relatively few in number compared to the other disciplines, and the rate of our improvement by such "accidental" discoveries is simply tooslow to keep pace with the rest of our technical civilization. It will be evident in the remarks that follow, that the rapid development of mining education, research, and the industry are extremely interdependent, and will be largely controlled by the amount of cooperation, support, and cross-fertilization that can be developed among all three.

Jan 1, 1961

By R. M. Hays

Jan 1, 1980

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By S. Iverson

Fall of ground accidents continue to be a source of injury in underground metal mines. MSHA accident statistics indicate that most rock fall accidents occur at a new face where drilling and blasting methods are used. Removing loose rock by scaling is imperative to removing the potential for rock fall injury. Detection of potentially loose rock could improve the scaling process and result in fewer rock falls. Infrared thermal imaging cameras were investigated as far back as 1966 as a tool for loose rock detection. Early on it was clear that sensitivity (e.g. detectable temperature increment) is a key factor in this application. Both pixel resolution and temperature resolution have greatly improved with modern instruments. This paper describes an evaluation of modern infrared thermal imaging camera technology to detect loose rock conditions at six underground metal mines in the western U.S. It was found that thermal images provide a high resolution visual discrimination between loose rock and intact rock. However, detecting loose rock was difficult in cases where the rock and ventilation air were at the same temperature. Loose rock was detected when rock was both warmer and cooler than the ventilation air temperature. Warm rock with cool ventilation air provided the best conditions for detection.

Feb 23, 2014

By J. D. Miller

Contact time during bubble/particle collision is calculated by taking into considera¬tion the effect of bubble and particle motion, buoyant force, bubble size, and particle size and specific gravity density for different cases of collision. From this motion analysis approach for the prediction of contact times and from bubble attachment-time measurements,, fundamental aspects of flotation such as flotability, kinetics, and separation can be explained and are discussed with respect to the effects of bubble/particle motion, bubble size, particle size, and attachment time.

Jan 1, 1987

By S. K. Ghosh

This paper discusses how the information on ash composition, ash-fusion temperatures, and ash-slag viscosity can be utilized to predict slagging and fouling potentials of a particular coal. A review of several empirical parameters which are commonly in use for determining such potentials is given. Also, some guideline values for interpreting the relative propensity of slagging and fouling of various types of coal are provided.

Jan 1, 1983

By Ken Pill, Jennifer Nyman, Liz Moran, Keaton Belli, Chelsea Bokman

The Moab Uranium Mill Tailings Remedial Action (UMTRA) Project Site (Site) is a former uranium-ore processing facility near Moab, Utah, where production ended in 1984. The United States Department of Energy Office of Environmental Management (DOE-EM) is responsible for remediating the site to meet 40 Code of Federal Regulations (CFR) 192 standards promulgated by the United States Environmental Protection Agency under the authority of the Nuclear Regulatory Commission (NRC). Tailings from the former mill were stored in an unlined impoundment (tailings pile), totaling 16 million tons of waste material. Surface cleanup has been ongoing since 2009 and consists of removal and transport of tailings via rail to an off-site disposal facility in Crescent Junction, Utah, with an estimated completion date around 2029. Gravity-driven migration of tailings fluids and recharge through the tailings pile and former on-site ore storage areas in the northeastern part of the site led to contamination of site soil and groundwater. The primary contaminant of concern is ammonia, which was present in fluids used in the milling process (DOE 2003). Uranium is a contaminant of potential concern. An interim groundwater remedy is currently in place that utilizes a system of extraction and injection wells to limit discharge of contaminated groundwater into the nearby Colorado River. Exceedance of surface water standards for ammonia are a principal concern due to potential endangered species fish habitat areas along the Colorado River adjacent to the Site. When necessary, surface water diversion is used to lower surface water ammonia concentrations when suitable habitats develop for endangered young-of-year fish. Once surface cleanup concludes and the tailings pile is removed, a formal groundwater remedy must be selected and documented in a Groundwater Compliance Action Plan (GCAP). Under Title 1 of the Uranium Mill Tailings Radiation Control Act, natural flushing (i.e., monitored natural attenuation), may be selected as the groundwater remedy if it can be demonstrated that the remedy will achieve groundwater standards within 100 years. The 40 CFR 192 groundwater standard for uranium is 44 micrograms per liter (μg/L), and the target groundwater concentration of ammonia based on adverse effects on local fish species is 3 milligrams per liter (mg/L). A collaboration with Geosyntec Consultants, Inc. (Geosyntec), the Moab UMTRA Project team, the DOE Office of Legacy Management, the DOE-EM, and the Network of National Laboratories for Environmental Management and Stewardship was held in 2022 with the goal to generate actionable recommendations to develop a GCAP for the Site. The primary recommendation was development of a groundwater fate and transport model to predict the remedial timeframe under various groundwater remedies. This paper presents the results of soil and groundwater sampling, geochemical modelling, and laboratory column and batch reactor testing that will be used to parameterize a numerical model for estimating the remedial timeframe under various scenarios, including natural flushing.

Feb 1, 2025

By Savita Schlesinger, Mike Hanna, Nathan Scalla, James O’Shaughnessy, Steve Miller

Loudoun Water’s Quarry A (Milestone Reservoir) project involves conversion of a rock quarry to a billion-gallon raw water reservoir. The project includes a new 40 MGD pump station, deep intake shaft, and three drill and blast intake tunnels for accessing the reservoir. Due to concerns regarding constructability and construction risks, the project design was paused while a Construction Manager At-Risk (CMAR) contractor was procured. The CMAR contractor was engaged collaboratively with the design team to provide risk and constructability input for refining the design. Aspects of the original design, design modifications, and benefits of the CMAR collaboration will be presented.

Jun 13, 2023

By Robert G. Beverly

The presence of radioactivity in uranium mill wastes has resulted in somewhat unique waste disposal methods. In addition to the common problems of disposing of large quantities of solid wastes, neutralizing acids, minimizing dissolved heavy metals, and clarifying all liquid effluents, the uranium mill operator must sample and analyze liquid effluents for micro-micro quantities of radionuclides such as, radium-226, thorium-230 and lead-210. Special disposal methods or decontamination procedures are required to meet the stringent limitations established by the U. S. Atomic Energy Commission on the concentration of radionuclides in liquid effluents. Routine monitoring of the receiving stream is also normally required. In recent years there has been a growing concern about the radioactivity remaining in the uranium mill tailings, particularly at the sites of shut-down or dismantled mills. The State of Colorado, in cooperation with the industry, has adopted regulations for stabilization of inactive uranium mill tailings. The Mining and Metals Division of Union Carbide operates mills for the recovery of uranium and vanadium at Uravan and Rifle in Colorado and a mill in the Gas Hills of Wyoming for uranium production. The company also owns former mill sites on which mill tailings are located at Maybell, Rifle, and Slick Rock in Colorado and at Green River, Utah. The purpose of this paper is to describe the methods used by a few uranium mills, largely those operated by Union Carbide Corporation, to dispose of radioactive wastes, to discuss briefly the regulations under which the mills operate, and to present reference information on the subject.

Jan 1, 1968

By Fernando Jorge Dick

Artificial sulphides have been produced on the surfaces of heavy metal-oxide, minerals at elevated temperatures (1) and these sulphides gave consistently similar flotation characteristics as the respective natural sulphides. In the case of tin, the only natural tin sulphide known is herzembergite (SnS) which is found only in minor quantities, and its flotation behavior is not known. Balberyszki, Dorenfeld, and Carmi reported (2) tests with artificial tin oxide and pure cassiterite treated with hydrogen sulphide at temperatures above 750oc. They confirmed that the product could be floated in acid pulps. However, iron sulphides derived from pyrite, limonite, and hematite which are generally the major impurities in tin bearing ores could not be separated from tin sulphides under the conditions used by previous investigators. As a practical matter, if complex tin ores or complex low grade tin concentrates are to be treated by this process, it is necessary to be able to separate sulphidized cassiterite from other sulphidized minerals in the feed. The major metallic minerals, by weight, in complex tin ores are the iron minerals--pyrite, hematite, limonite, magnetite and pyrrhotite. These minerals become (or remain) sulphidized during the sulphidization process.

Jan 1, 1978

By S. A. Sanderson

The last two decades have witnessed the resurgence in popularity of a century old tool for shaping laws and public policy – the ballot initiative. In recent years, anti-mining special interests have used the initiative process to secure voter approval of measures to ban modern surface mining for gold and silver. In November 1998, voters in Montana approved such a measure1 – the effects of which have been devastating to the mining industry in that state. In November 1999, anti-mining groups sought to place a nearly identical provision on the general election ballot in Colorado. They did not succeed, but the battle over mining’s future continues in the most important forum of all – the court of public opinion. The Colorado measure failed, in large part, because its proponents failed to convey a positive environmental theme. The mining industry also exercised early-on the rights available under state law for administrative and judicial review of the initiative, instead of relying upon the limited relief that would have been available had it waited until after the secretary of state approved the measure for the November election ballot. This article will summarize the ballot initiative process in Colorado and the proceedings that took place over Initiative No. 215.

Jan 1, 2001

By Arash Nikvar‑Hassani, Timothy Batchler, Lianyang Zhang

Recently, a new hybrid geopolymer/biopolymer (GP/BP) cementitious material was developed for improving the performance of pumpable roof supports in underground mines. This study demonstrates the application of the hybrid GP/BP cementitious material and validates its effectiveness in full-scale. In this regard, eight (8) full-size (0.61 m diameter and 1.52 m height) cribs were produced in collaboration with Minova International Ltd and tested at the National Institute for Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS) Laboratory. These full-size cribs were produced with different material configurations to evaluate the effect of water to solid (W/S) ratio, Portland cement (PC) content, and BP dosage. The results demonstrated and validated the effectiveness of the hybrid GP/BP cementitious material in increasing the peak and residual bearing capacities of pumpable cribs and eliminating the issue of deterioration when exposed to air compared with the conventional Portland cement/fly ash (PC/FA) cementitious material currently used in practice. On average, the peak uniaxial compressive strength (UCS) and the highest residual UCS after peak of the full-size cribs produced from the hybrid GP/BP cementitious material are 1.90 and 1.33 times of those of the PC/FA-based full-size cribs by one company and 2.32 and 1.66 times of those of the PC/FA based full-size cribs by the other company, respectively.

Feb 6, 2024