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By L. Donovan Clark

The term "powder factor" is almost universally accepted as the measure of the efficiency of a blasting program. It represents the economics of blasting since it designates quantity of explosive (thereby providing quality control in rock fragmentation) in terms of the associated volume broken. It is the wide use of this concept that explains the interest shown in an approach to rock blasting preferred by A. W. and Z. W. Daw* in a treatise on 3 blasting (1) substantiating its use in the form, Q = CVW3 for single shot hole, where Q = quantity of explosive lb Cv = blasting coefficient W3 = unit volume of rock It is obvious that the term Cv could also be called the apparent powder factor should the equation be written in the form, Cv = Q/W3 (lb per cubic unit). However, while the approach was ingenious** and the practical applications straightforward, their original, rather limited experimental work, along with certain assumptions, was questioned.

Jan 1, 1970

By M. C. Fuerstenau

A number of interesting and. important phenomena were revealed during a study of the response of beryl to sulfonate flotation (1). Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH = 3. 0, about three ppm Fe.+++ increased recovery of leached beryl from about 60 to 100 per cent, whereas about four ppm Ca++ reduced the recovery from 60 to 2 per cent. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper "Sulfonate Flotation of Beryl", (1) even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation¬ sulfonates are precipitated immediately in solution. That is, blueish-white clouds .were noted to form after given additions of salts to. known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe (RSC3)2OH and that bonding to the surface occurs through the hydrogen of the hydroxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems lit the presence of various cations at various values of pH.

Jan 1, 1964

By Cary Hirner, Tony Cicchetti, Daniel G. Cressman, Jeff F. Wallace, Prapan Dave, Malcolm Sheehan

The City of Toronto is currently undertaking the design of the Black Creek Sanitary Trunk Sewer Relief Project. The Project involves the design and construction of approximately 20 kilometers of tunnel through shale rock of the Georgian Bay Formation and soft ground soil consisting of glacial till, glaciolacustrine and glaciofluvial sand, silt and clay deposits. The 20 kilometer alignment has been split into four sections of tunnel (1) the 12.9 km, 3.0 meter diameter Keele Trunk Relief Sewer, (2) the 2.9 km, 1.5 meter diameter Keele Trunk Relief Sewer Microtunnel, (3) the 3.9 km, 1.8 meter diameter Jane Relief Sewer, and (4) the 0.5 km,1.5 meter diameter Combined Sewer Overflow Storage Tunnel. Additionally, one 40,000 m3 wet weather flow (WWF) storage tank and numerous WWF connection shafts are to be constructed and connected to the Keele Trunk Relief Sewer to pick up WWF from existing outfalls currently discharging to Black Creek. The anticipated cost of the project is approximately $600 million with construction of the Project’s Phase One Works, the Keele Trunk Relief Sewer and Jane Relief Sewer, scheduled to commence in 2025. This paper provides an overview of the project in terms of the anticipated geotechnical conditions, the scheme developed for design and construction of the tunnel system and the associated schedule and procurement strategy. The consideration for planning of the tunnel system, the risk-based analysis and decision-making process are presented and form the basis for selection of a precast tunnel lining support method in the rock and soft ground.

Jun 13, 2023

By R. Shields

"Hard rock mines move large volumes of material. But the conveyors essential to this movement suffer lots of problems, including carryback, spillage, dust, and belt wander. Many of these issues are created at the transfer points where the belts are loaded. This presentation will start with an overview of the latest transfer point systems that incorporate safety and serviceability by design. It will then report on recent projects. One project is the Conveyor B Transfer at the Coeur Rochester silver mine near Lovelock, Nevada. Here performance was improved with the installation of belt support cradles, engineered chute walls with external wear liner, and a compact dust collector. A second project is the improvement of belt support idlers and skirtboard sealing in a long loading zone of a conveyor under the concentrator at an Arizona copper mine. THE IMPORTANCE OF TRANSFER POINTS Conveyors are essential in mine material handling. Their performance will often make the difference in mine productivity and profitability. A key to conveyor performance are the transfer points where the conveyor belt is loaded and discharges. At these transfer points, many of the problems encountered with the conveyor system are created. The problems that arise at the transfer stations include off-center and segregated loading, mistracking, blockages and plugging. And there are a variety of problems originating with fugitive material—cargo released in the form of carryback, spillage, or airborne dust—that are created or exacerbated in the transfer points. These fugitive materials turn into other conveyor-related problems, including shortened component life, unplanned outages for conveyor maintenance, unexpectedly high labor costs for maintenance and cleanup, worker health and safety problems, and issues with community relations. As estimate attributed to the U.S. Mine Safety and Health Administration (MSHA) notes that 85 percent of conveyor maintenance is a result of fugitive material at conveyor transfer points. TECHNOLOGIES TO IMPROVE TRANSFER POINTS A number of techniques to improve the performance of conveyor transfer points have been developed. They include: • Absorbing impact, to prevent damage to belt, belt support systems, and conveyor structure, and reduce spillage caused by the impact energy arising from long material drops or large lumps of material loaded onto the receiving belt. • Stabilizing the belt line, to eliminate sag that allows spillage and encourages material entrapment that can damage the belt. • Protecting the skirtboard seals, by sheltering the sealing strips from the mass of cargo pushing material toward the edges of the belt. • Using self-adjusting, multiple-barrier edge seals, to keep material on the belt by providing long-lived seal efficiency with minimum maintenance requirements. • Controlling and centering the belt’s path, to eliminate belt wander and the spillage and damage it can cause. • Allowing dust to settle, through the incorporation of chutework that provides expanded stilling zone and the use of dust curtains at the points where the belt enters and exits the transfer. • Adding supplemental dust control systems, through the installation of systems for passive dust gathering, water-based dust suppression, and/or active dust collection."

Jan 1, 2017

By Y. C. Kim

One aspect of long-range mine planning in an open-pit mine is first to define the ultimate pit limit, i.e., the projected size and shape of the pit at the end of its life. This chapter is concerned with various techniques that are currently in use today in determining the ultimate pit limits using the computer. Prior to the early 1960's, open-pit limits analyses were entirely performed manually. This manual technique has been well explained by Soderberg and Rausch in Surface Mining (1968). Soderberg and Rausch also explain clearly the need for establishing the ultimate pit limits in long-range mine planning, i.e., location of surface facilities, dumps, etc. Consequently, the need for ultimate pit limit design will not be reiterated here. Nor will the definitions of the most commonly accepted terminologies such as break-even stripping ratio, economic cutoff grade, ultimate and working slope angles, preproduction stripping, etc. be repeated here. Briefly, the objective of the ultimate pit limit design (which is also frequently referred to as pit design in short) is to determine the projected final pit limits of an ore body and its associated projected grade and tonnage, which will maximize some prespecified economic criteria while satisfying practical operational requirements.

Jan 1, 1979

By Alden B. Carpenter

Oil-field brines have been collected and analyzed from Jurassic and Cretaceous rocks in the Mississippi Salt Dome Basin, from Jurassic and Lower Cretaceous rocks, southwestern Arkansas, and from Ordovician and Silurian rocks, southern Michigan. All of these brines are genetically related to evaporites and appear to be brines expelled from halite-bearing rocks, presumably during compaction. The brines in rocks closest to the halite-bearing rocks are uniformly low in lead and zinc suggesting that the metals in metal-rich brines are not acquired within evaporite sequences. The metals in metal- rich brines in Mississippi and in Russia appear to be derived from red beds and may have been originally associated with ferric iron oxyhydroxides. Reduction of these compounds by migrating hydrocarbons appears to release lead and zinc to the associated brines accompanied by the fomation of authigenic ankerite.

Jan 1, 1979

By T. W. West

During the design and construction of a coal preparation facility, there are many items that can cause serious problems if not properly handled in the early stages of a project. These problems can be a detriment to smooth owner/ contractor relationships, the designing of a flow sheet, the selection of equipment, the design of the facility, the maintenance of schedule and budget, and a smooth start-up. It is the purpose of this presentation to identify some of these problems and to suggest steps that can be taken to reduce or eliminate their impact.

Jan 1, 1977

By P. R. Taylor

A reaction is evaluated by which heated and pressurized water is used to precipitate metal oxides from loaded Kelex 100 complexes. Pure copper oxide (CuO) and pure nickel (Nio) in powder form, and ranging in average size from 12 to 25 micrometers, were found to precipitate from copper and nickel loaded Kelex 100/kerosene complexes, by water heated and pressurized to between 374 and 400 °c and 2170 psig (148 atm) and 3500 psig (238 atm). The precipitation is suggested to result from hydrolysis of the metal, following exchange for the hydrogen in the phenolic hydroxyl of the Kelex 100 structure, enhanced by the conditions provided by heated and pressurized water. The reaction is believed to have the characteristics of homogeneous nucleation and heterogeneous growth. The effects of temperature, pressure, initial metal concentration and seed addition on the kinetics of the process were studied. In addition, characterization studies were performed on the reaction products. A detailed discussion of the experimental results is presented.

Jan 1, 1992

By Michael S. Moats, John Bailey Fletcher

Wear rates of grinding media can be misrepresented by marked ball wear tests (MBWT). Galvanic interactions between dissimilar grinding media can be affected by the chromium content in the media and the presence of oxygen in the environment. Corrosion, one component of wear, can be affected by many variables. Corrosion rates and corrosion potentials for modern high chromium white iron (HCWI) and high carbon steel (HCS) grinding media samples were obtained through electrochemical testing. In this study, the impact of chromium content in the grinding media and the dissolved oxygen in a simulated mill water solution on corrosion rates and potentials was examined. Increasing chromium content in HCWI above 15 weight percent increases the corrosion potential and decreases corrosion rate. Removing most of the oxygen from the solution lowers both the corrosion potential and corrosion rate of the materials tested. The electrochemical results were examined to model possible galvanic coupling effects on corrosion rates. Galvanic coupling between HCS and HCWI could cause differences in corrosion rates for almost all scenarios modeled. Based on the galvanic coupling analysis, MBWT results could be impacted by mixing HCWI and HCS in a ball mill charge. This impact is predicted to be more significant when dissolved oxygen is present in the mill water and as the chromium content of HCWI is above 15 weight percent.

Dec 21, 2022

By Osvaldo A. Bascur

Standards and Technology for bringing information at the desktop has greatly evolved in recent years. The benefits to be realized depend on how these new tools are embraced at the performer level. A key operating challenge is to ensure collective effort is geared towards the most efficient achievement of identified operating and corporate objectives. Presentation, application and data repository modular software are emerging in successful client server applications. The industrial desktop emerges as the new tool for continuous improvement and innovation in industrial operations. Here, process information, reliability maintenance, process simulation, production schedules, performance monitoring are integrated using Microsoft enabling tools at the desktop. A workflow model is presented to assist in implementing a strategic information system in metallurgical plants.

Jan 1, 1996

By Björn Johansson

"SUMMARY Every tunnel designer has to consider the power of water ingress when designing a new tunnel. Either you choose solutions with simple methods to divert the ingress water or a robust system with the intention that it will give gain on low maintenance costs and a long lifetime. This article describes a new method to divert ingress water in a robust way and more economical than traditional concrete lined tunnels. This system is based on a bolt grid suspending a water tight membrane, which is reinforced and covered with sprayed concrete. The method has been in limited use in Sweden since 2005 and with continuous improvement, still going on, it is now applied for the large project “Stockholm Bypass”, a 21km long highway project. TUNNEL MAINTENANCE RELATED TO WATER INGRESS The Swedish Transport Administration maintain approximately 190 various tunnels that is constructed by a number of different methods, (Swedish Transport Adm 2015). Commonly the ground conditions are good and fairly low ground support is needed. Contrary water and winter conditions can be sever, which gives high impact onto the tunnel design and in particular methods to protect against “frost and water ingress”. During a tunnels lifetime it is common that maintenance related to water ingress occurs several times and sometimes frequent occasions every year. Such maintenance costs and consequences of lost open time for the tunnel can rapidly become higher than the initial cost of the tunnel. Thereby it is obvious that spending time during design to evaluate requirements for a suitable system against water ingress is preferred. Icicles Icicles are formed when water is below freezing degrees and drips or run from an ingress point. At very cold conditions also water flows running at high velocity freeze into ice and a rapid growth can appear. If the integrity of the tunnel traffic area is interfered by icicles they urgently have to be removed before they cause an accident. Typically the tunnel or a part of the tunnel must be closed to do such maintenance. TUNNELS FROST AND WATER INGRESS PROTECTION IN SWEDEN In Sweden methods to perform “frost and water ingress protection” are primary developed for drill and blast tunnels as it is most common tunneling method. The foundation Swedish Rock Engineering Research has done a comprehensive report SveBeFo Rapport 77 that describes water and frost prevention in Swedish tunnels up to year 2005. Below is only slight description of those various methods. Lately some more attention is paid to concrete lined tunnels made by TBM since TBMs successfully built water tight tunnels in City Tunnel (Malmö) and Hallandsås Project. When environmental demands require maintained ground water levels, water tight tunnels made by pressurized concrete lining becomes more economical and on the same time also becomes protected from icicles and water drips."

Jan 1, 2016

By S. Miller, A. Krasner, M. Sizintsev, S. Schafrik, H. -P. Chiu, J. Sottile, A. Rajvanshi, Z. Agioutantis

In recent years, a great deal of effort has been put into automating mining equipment with the goal of improving worker health and safety and increasing mine productivity. Significant progress has been made in automating mining equipment such as load-haul-dumps and drills in underground environments where global positioning systems are unavailable. This paper addresses automating the task of positioning the shuttle-car (SC) under the continuous-miner (CM) coaldischarge conveyor during cutting and loading operations. A stereo depth camera is mounted on the SC. Machine learning based algorithms are applied on the camera’s output to identify the CM discharge conveyor and segment the scene into various regions such as roof, ribs, and personnel. This information is used to plan the shuttle car path to the CM discharge conveyor. The approach currently uses a 1/6th scale continuous miner and shuttle car in an appropriately scaled mock mine

Mar 2, 2022

By Aline Tatom

This paper presents numerical and experimen¬tal results dealing with the application of ferric ion oxidation of uranium in acidic media. Conclusions are derived from matching numerical results to experimental data taken on one-dimensional laboratory leaches using ore from a South Texas Coastal plain deposit. Since the numerical results can be made quite general, we are able to extract and quantify the effects of oxidant concentration, flow velocity, mass transfer, chemical kinetics, and competitive oxidant consumers (pyrite and molybdenite) on the experimental results. Our results suggest that the leaching of uranium is a mass transfer controlled while that of pyrite is kinetically controlled.

Jan 1, 1981

By Garry M. Hughes

Lynn lake, Manitoha, where Sherritt has operated a copper-nickel mine since 1954, is located north of the 56th parallel approximately SOO miles north of Winnipeg. Sherritt's new, 3,000 tpd, copper-zinc Fox Mine is situated 30 miles southwest of Lynn lake. This paper focuses on the Fox Mine concentrator, hut first some background information. Sherritt Gordon Mines Limited started mining operations as a copper-zinc producer in 1931 at Sherridon, Manitoba, 150 miles south of Lynn Lake. As Sherridon fizzled out development of a series of nickel-copper orebodies commenced at Lynn Lake. The Forward process was developed to treat the nickel concentrate from the Lynn concentrator. Sherritt's ammonia leaching process is now history and is expected to gain more prominence as pressure is applied to the mining industry for closer environmental control. But few are aware of the fact that the present Lynn Lake crushing plant and concentrator were dismantled in the autumn of 1951 and freighted from Sherridon by tractor train during the winters of 1952 and 1953. The copper-zinc orehody at Fox Mine was discovered early in 1961 by geophysical methods which included both airborne and ground surveys. It is part of a ,large body of massive and semi-massive sulphides consisting chiefly of pyrite; with chalcopyrite, sphalerite (containing 7-9% iron) and pyrrhotite in varying proportions which occur within a series of volcanic and sedimentary rocks. The total mineralized zone is a lenticular body with a minimum average length and width of 1,350 feet and 66 feet respectively, to the explored depth of 2,000 feet. The average sulphide content is 67%. Higher zinc zones are masses of pyrite grains cemented by sphalerite with lower than average copper content. Zones higher in copper and lower in zinc are slightly more quartzose. Gold and silver are present in small amounts roughly proportional to the copper content.

Jan 1, 1971

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

By Mark L. Munsell

In recent years, miners have tried many approaches to maintenance such as: - Highly sophisticated computerized programs. - large planning groups designed to preplan and schedule work. - Contract maintenance. - Break down maintenance. Each of these approaches has faced the added constraints: - High replacement cost of equipment necessitating longer useful equipment life - management?s increased scrutiny of all indirect costs such as maintenance. Faced with these factors, what system of maintenance control is right? After visiting many properties recently, it appears there is no right system. Maintenance programs need to be tailored to the people and production constraints that occur at an individual property.

Jan 1, 1976

By P. L. Yorio, D. R. Willmer

"The current paper presents the results of a study designed to explore the types of practices that are fundamentally important to developing and maintaining comprehensive risk-based health and safety management systems (HSMS) in mining organizations. Eighteen practicing health and safety (H&S) executives, managers, and professionals from a variety of mining commodities were asked to assess the fundamental importance of 20 distinct elements and 133 different practices assembled from a review of several HSMS consensus standards. The research approach assumes that developing and maintaining a robust HSMS requires unwavering attention to activities designed to either: 1) directly contribute to a risk management system’s plan-do-check-act cycle; or 2) build an organization’s internal infrastructure without which the cycle cannot be sustained. The results of this study suggest that the following areas require consistent focus and attention: Leadership Development; Accountability; Knowledge, Skills, and Abilities Development; System Coordination; Culture Enhancement; Behavior Optimization; and Risk Management Studies. Each element and its corresponding top-ranked and top-rated practices are discussed.INTRODUCTION Since the time of the Industrial Revolution, occupational health and safety (H&S) management has been a topic of practitioner thought and academic inquiry (1). In the U.S., decades of regulation and research have resulted in a surplus of prescriptive information (techniques, tools, approaches, standards, programs, practices, policies, etc.). With an abundance of such information, a simple H&S solution to address a problem in the U.S. mining industry may seem straightforward. Counter to this assertion, however, some evidence suggests that the abundance of information may create complexity and cause confusion in the minds of organizational leaders and H&S managers, ultimately discouraging the voluntary pursuit of a sound approach (2). In line with this perspective, in 2006 the U.S. National Mining Association (NMA) formed an independent commission to examine H&S management issues within the mining industry. The findings of the commission called for the mining industry to adopt a risk-based management paradigm. In the presentation of its findings, the commission stated that “…every mine should employ a sound risk-analysis process, should conduct a risk analysis, and should develop a management plan to address significant hazards identified by the analysis” (3). Grounded in the well-known plan-do-check-act cycle, the recommended risk management system allows for mines to ground strategic management choices in their mine-specific hazards and risk profiles"

Jan 1, 2015

By Michael Hood

Subsidence profiles above two adjacent panels in Illinois are compared with pro- files predicting subsidence behavior obtained using the (i) National Coal Board (NCB, 1975) method, (ii) the profile function method and (iii) the influence function method. The NCB method predicts the maximum subsidence values at the center of the troughs accurately, but, the overall shapes of these predicted profiles do not match the profiles from the measured data well. Consistent values for the angles of draw were measured but these angles were different in the transverse (average value 43 degrees) and in the longitudinal (average value 17.5 degrees) directions. Time dependent subsidence effects are shown to be small but measurable. These displacements continue at a linear rate for at least a 12 month period. A comparison of measured horizontal distances, interpreted as horizontal strain, and the NCB predictions for strain shows that the peak measured strains are greater by a factor f about four than the predicted strains. The relationship between surface curvature and strain is investigated. Problems associated with calculation of surface curvatures from vertical displacement data are highlighted and a recommendation is made for future studies to consider direct measurement of this parameter. Surface curvatures above a moving face are found to be about three times less than the curvatures at the stationary end of the panel. On the other hand, a hyperbolic tangent profile function is shown to serve as an accurate predictive tool for subsidence behavior in two adjacent longwall panels at Old Ben Number 24 mine in Illinois. This function predicts not only the vertical displacements but also the surface curvatures above both panels. Influence functions are shown to be more problematic, although potentially more flexible, in their application than the profile functions.

Jan 1, 1982

By Erica McGlynn, Brian Negrea, Lance Jackson

There was no need for the people of Cleveland to ask “Where does the raw sewage go? We want to know!” because it was clear. The raw sewage was being discharged into Lake Erie during heavy rainfall events due to the outdated design of the combined sewer system. In efforts to resolve this ongoing issue for the City of Cleveland, the Northeast Ohio Regional Sewer District developed Project Clean Lake in collaboration with the US EPA. Project Clean Lake is a 25-year, $3 billion program consisting of seven large-diameter CSO storage tunnels to be constructed beneath the city’s existing infrastructure. The first four tunnels have been completed using traditional hard rock TBM excavation methods. The fifth tunnel, the Shoreline Storage Tunnel Project, presents unique challenges and complexities as it will be the first large-diameter EPB TBM to dig under the City of Cleveland. The project itself consists of one tunnel drive 14,100' (2.7 miles) in length, two pipe jacking tunnels, three large slurry wall shafts, two diversion structures, and three regulator reconstructions. Upon completion of the project, 12 permitted CSO locations along Lake Erie will be taken offline, reducing overflow volumes by approximately 350 million gallons per year. This paper will discuss the current status of construction and the chosen means and methods, including the myriad of nuanced differences between hard rock and EPB TBM tunneling methods. Particular attention will be given to the site preparation, setup, and organization; TBM assembly; and TBM launching practices.

Jun 13, 2023

By W. J. Martin

At the termination of mining, the quality of ground water in the ore-zone aquifer must be returned to a condition predetermined by the permitting agency. To immobilize the redox-sensitive elements (e.g., uranium, arsenic, selenium, molybdenum), it has been suggested that a reducing agent be circulated through the leached ore zone. We have conducted laboratory experiments to test the ability of sodium sulfide as such a reducing agent. Sodium sulfide lowered the redox potential of the effluent such that insoluble minerals containing the redox-sensitive elements should be stable. The uranium concentration of the solution decreased by more than three orders of magnitude. In column experiments, by the time ten pore volumes of the sulfide solution had flowed through, sulfide minerals were forming. The experimental results indicate that the addition of sodium sulfide should cause the chemical reduction of the leached sediments, thereby producing long-term stability of the ground-water/sediment system.

Jan 1, 1986