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By Madan M. Singh

Section 516 of Public Law (PL) 95-87, commonly known as the Surface Mining Control and Reclamation Act of 1977 (SMCRA), requires that underground coal mine operators must "adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mine stability, and maintain the value and reasonable foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." Implied in the constraints of Section 516(b)(1) of SMCRA is a determination of what constitutes "material damage" to surface structures, renewable resource lands, and the capacity for sequential land use following underground mining. The authors have already briefly addressed the subject of damage criteria in relation to surface structures (Bhattacharya et al, 1984). In this paper, an attempt is made to provide quantitative guidelines to ascertain material damage to renewable resource lands, although the data available to establish these criteria are considerably more limited than is the case for surface structures. Besides, many more variables influence the severity of the impact at a given site, making the task of assigning stringent ground movement limits even more complex. This often necessitated use of professional judgement and occasional reverting to a qualitative approach. Hence the reader is cautioned at the very outset that the quantitative limits presented herein are approximate and are primarily intended to serve as rough guides for ascertaining the extent of damage to the renewable resource lands under consideration, and that depending on site-specific conditions the actual damage incurred may differ significantly from that predicted by the proposed criteria. The authors, however, feel that the criteria suggested are somewhat conservative, but realistic. The actual damage observed should generally be less severe than predicted by these criteria. It may also be clarified here that the term "subsidence", as used in this paper, implies the total phenomenon of surface and subsurface effects associated with the mining of minerals and not only the vertical displacement of the surface as is sometimes inferred in the literature.

Jan 1, 1984

By Ellen Amoako Afful, Michael Moats, Guang Xu, Ashish Kakoria

Electrowinning and solvent extraction are crucial steps in the production of high-purity copper. However, safety concerns have been raised regarding the acid mist generated from the electrowinning process. The mist generated results in health risks to workers and damage to machinery and infrastructure. Currently, chemicals and pellets are used to control acid mist. However, the effectiveness of these controls may vary depending on the type of organic solvent used in the solvent extraction process, which can influence the generation of acid mist. This study aims to evaluate the impacts of organic solvents and surfactants on acid mist suppression. In this study, an electrolyte is contacted with organic solvents to simulate the solvent extraction. The electrolyte is dosed with 20 mg/L of surfactant at each contact. Acid mist testing is performed on the electrolyte separated from the organic phase at the end of the solvent extraction step. The mist collected is analyzed to determine the level of acid mist generated. The results of this study indicate that organic solvents and surfactants showed significant acid mist suppression, but with somewhat different suppression efficiencies. After first contact, Licorice and the organic, for instance, showed a suppression efficiency of up to 69.7% but its efficiency gradually decreased as the number of contacts increased.

Feb 1, 2025

By M. M. Fine

One of the most persistent topics at technical gatherings and in the recent scientific press has been the reduction of iron ore. To cite some of them, in May 1960, a symposium on the subject was sponsored by the Electrochemical Society. The proceedings, comprising two dozen papers, were later published.3/ More recently, November 1966, a similar gathering took place at Michigan Technological University, Houghton, Mich. The latest meeting was the International Congress on Production and Utilization of Reduced Materials, Evian, France, May 1967. If the volume of literature, symposia and conferences is a measure of industry concern, then current interest must be at a high level. To the casual observer of the metallurgical scene, the abiding and recurring attention to iron ore reduction outside the blast furnace must be somewhat puzzling in that so much research endeavor has resulted in so little commercial activity.

Jan 1, 1968

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 J. Kenneth Wittle

The DC Graphite Melter has been shown to be capable of processing radioactive waste materials. The process is characterized by its high temperature capability and operation in a closed system. From an environmental perspective, the control of emissions coupled with destruction for hazardous organic materials is mandatory. These same characteristics may be applicable to the minerals processing industry. Under normal operation, the system reaches temperatures for nominal operation of 1600°C, with an arc temperature in the order of 5000°C. The system temperature is determined by the melt temperature of the material being processed. In testing of a 750 lb/hour unit, temperatures of 2200°C were reached. Current focus is on finding waste treatment and metals recovery opportunities in the metals processing industry for his innovative technology.

Jan 1, 1999

By Mark C. Williams, Thomas P. Meloy

Particle shape characterization is a complex task made more difficult because of the human eye's sophisticated recognition of shapes, giving rise to the assumption that shape analysis is considered a simple problem. Further exacerbating the problem is the question of whether particles have a general shape. Old and new shape measuring techniques are discussed, particularly the new image analysis methods techniques such as Fourier, Haar, Walsh and Delta. Problems with the current image analysis equipment and future research equipment needs are presented.

Jan 1, 1989

By J. Tuzson, H. McL. Clark

Introduction Wear of pumps, wet cyclones and pipelines by suspended solid particles will impact their operating economies by limiting their useful life, reducing their reliability and increasing the amount of servicing. Erosion is considered a materials problem. The empirical solution consists of testing different materials in field applications. Such tests are time consuming and expensive. The prediction of localized wear rates, life estimates and appropriate material selection demand a better understanding of the slurry wear process in environments corresponding to those found in working equipment. Key words: Wear, Slurry abrasion, Coriolis erosion tester The slurry wear process Solid particles suspended in liquid generally move with the flow, but such particles deviate under the centrifugal and Coriolis forces encountered in pumps. The concentration of particles will increase, and a solid layer or bed may accumulate if the acceleration is directed against the flow passage wall. Large particles in dilute suspensions may impact the wall. dissipating their kinetic energies and removing material. However, particles smaller than about 11)(1 µm encounter great drag when moving through the liquid. and such par¬ticles have little kinetic energy left when they reach the wall. They cannot penetrate the stagnant boundary layers present in pumps. Therefore, small particles tend to form beds that slide along the wall, removing material by a process that could he called sliding erosion or wet abrasion. Wear by impact erosion from large particles in dilute slurries can he predicted by appropriate analytical and empirical methods. However, laboratory tests and calculations of wear rates that correspond to sliding erosion are more likely to correlate with field experience from wear under similar conditions. Specific energy Data from laboratory slurry erosion experiments have shown that the amount of material removed is approximately in proportion to the energy expended in the erosion process. Thus. the specific energy-energy expended in removing by erosion a unit volume of material-offers a simple, practical measure for the erosion resistance of materials. The concept was found to also apply to sliding erosion (Clark et al.. 1997). Generally, the study of the material-removal process in slurry erosion continues to remain a subject of research. Conceptually, if the flow velocities and accelerations could be calculated in a pump or pipeline, the energy dissipated at the passage walls could also be estimated, and the material removal rate would become known from the specific energy determined by laboratory tests. Slurry erosion testing Laboratory devices made specifically for slurry erosion testing may be grouped into the following: jet erosion devices, slurry pots and the Coriolis test machine (Pagalthivarthi and Helmly, 1992). Jet erosion devices use a slurry pump and nozzle to produce a high-velocity slurry jet that is directed at a flat material specimen, either perpendicularly or at some acute angle. Combined impact and sliding erosion are produced. but the processes cannot be separated, and the wear is difficult to assess except by weighing. Slurry pots consist of a cylindrical vessel containing the slurry of interest. In the slurry pot, test specimens are attached to a rotating arm. The samples are rotated in the slurry and experience local flow conditions that result in combined impact and sliding erosion. Wear depth measurements from detailed laboratory experiments have been successfully correlated with results from an analytical model of the process, and specific energy values have been calculated (Wong and Clark, 1995). In industrial use, the samples are weighed to determine the total material loss. Materials are ranked with respect to some reference material. The Coriolis erosion tester (Tuzson, 1984) consists of a rotor with a central cavity, from which two opposing radial passages lead out (Fig. 1). The slurry is fed to the centerof the rotor in one pass from a stirred overhead tank. The slurry particles are subjected to the Coriolis acceleration as they flow out through the radial passages. The material specimens are mounted into the radial passage walls facing the direction of rotation and are eroded by the particles that are pressed against them as they flow out radially. A narrow groove is worn into the sample within a few minutes, using a few gallons of slurry. Material removal is estimated accurately from profilometer traverses across the wear scar at different locations. The energy dissipated by the particles can be estimated, which leads to a well-defined experimental value for the specific energy.

Jan 1, 2000

By Jon C. Yingling

A control system for reducing peak loads on mine conveyor networks is proposed. The system involves continuous monitoring of flows into the conveyor network and section feeders with variable discharge capability. The control strategy uses differences in material transit times from various production units to the transfer points in the network to forecast load levels that will be intersected by the discharge of the controlled feeders over future time intervals. Feeder setpoint adjustments are made to prevent excessive peaks in the combined flows at the transfer points, while maintaining adequate feeder throughflow to avoid production bottlenecks.

Jan 1, 1992

By Brian K. Failon

Scale formation is a problem that affects many mineral processing systems because the processes require the use of large volumes of water. Scale composition may vary from circuit to circuit, but the scale deposition mechanisms and needs for prevention are often somewhat similar. Likewise, there is a degree of commonality in the prediction, detection, and elimination of scaling conditions in various water systems. This paper briefly reviews some of the conditions which lead to scale formation, as well as some of the common problems associated with unchecked scale growth. The primary focus of the paper is on the variety of chemical scale inhibitors available for use in mineral processing circuits, and the actions of each type. The means of predicting and detecting scaling tendencies are also addressed, and include both direct and indirect methods, i-e., stability index determination and chemical analysis of deposits.

Jan 1, 1986

By A. T. Yu

Technology and economies of scale have, in the past decade, brought about the emergence of giant vessels. Meanwhile, to answer the need for rapid dispatch, as a means of combating the proportionately far greater demurrage charges, shiploading and unloading speeds have soared (Ref. 1, 2, 3). As the loading and unloading rates have dramatically increased, so has the cloud of dust grown in unbearable proportions. It not only has threatened to be a real menace to machinery and men, but in certain instances has also seriously jeopardized fish and marine life (Ref. 4). In an era when ecology is king, dust in shiploading and unloading can no longer be shrugged off as a mere public nuisance, and its control is now duly recognized as of grave concern to all. Even if public outcry were not a problem, from the operator's own parochial point of view, dust can adversely affect productivity and the well-being of the operating personnel. Without adequate control, it can also result in costly equipment maintenance, particularly when the dust is micronic in size, and abrasive. The Hierarchy of Control Techniques Given the great fortune of not yet having to deal with gas and odors, in the jargon of pollution control, our problem is confined to having to control "particulates" only. To deal with "particulates", the myriad of dust control techniques can be utterly confusing to those who are not entirely well versed in the methodology. Our analysis of what is available to date results in the following hierarchy of logical preferences: 1. Prevention 2. Removal 3. Suppression 4. Containment 5. Dilution Since it deals with the root cause, prevention always outranks the cure. Once the dust is generated, removal nips it in the bud. Only when dust removal is

Jan 1, 1972

By P. Tsang

The stability of longwall chain pillars depends not only on the mechanical properties of coal and surrounding rocks, but also geological and mining conditions. In order to evaluate the effects of each, variable, the orthogonal experiment design was employed in this study for significance analysis. The study concluded that the stability of longwall chain pillars is mainly controlled by the ratio of pillar stress to pillar strength, the ratio of Young's moduluds of the roof to coal and floor to coal, entry width, pillar width and the internal friction angle of coal. Additionally, horizontal stress, panel width and mining height also play a significant role.

Jan 1, 1994

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By Fiona M. Doyle Garner

Hydrolytic stripping is the process whereby metal ions in a loaded solvent extractant are hydrolyzed by water, typically at 130°-200°C. Equilibrium hydrolytic stripping tests were done on Versatic 10 solutions of various metals, singly and in mixtures. Single solutions of Fe, Xi, Cu, Mg, and tin precipitated aFe2O3, Ni(OH)2, Cu2O, Mg(OH) 2 and ?Mn203 respectively during hydrolytic stripping. Several mixtures containing iron precipitated magnetic spinel ferrites, MFe20k. No other combinations formed mixed oxides. It is proposed that the mechanisms for hydrolysis and precipitation of iron in loaded Versa- tic solutions are similar to those for iron hydrolysis in aqueous solutions. Infrared spec- troscopy and thin-layer chromatography of mixed iron-nickel Versatic solutions indicated that mixed Fe-Ni carboxylate complexes are present. Magnetic interactions between mixed complexes are thought to be responsible for the homogeneous nucleation of magnetic mixed oxides in preference to single oxides.

Jan 1, 1984

By L. M. Litz

In reply to Mr. DeVries comments on my paper, I would like to say that it is true, as pointed out by Mr. DeVries, that under some special conditions, the use of high concentrations of hydrogen peroxide might provide higher short term in-situ …

Jan 1, 1982

By Salim Akhtar

The operation of a mineral processing plant with a complex flowsheet is represented by a mathematical operator. Such a representation permits a quantitative evaluation and monitoring of the separation processes in different sections of a processing plant, and gives an overall separation efficiency of the plant.

Jan 1, 1973

By L. Martin, M. Raffaldi, M. Stepan, D. Benton

The Office of Mine Safety and Health Research, Spokane Mining Research Division, is continuing its high-energy, high-displacement testing of field-scale shotcrete panels. A test program was developed to determine the relationship between applied force, displacement and energy for both unreinforced and reinforced shotcrete panels. Reinforcement options consisted of synthetic macro-fibers, sprayed polyurea liners, chain-link mesh, welded-wire mesh and combinations of them. During testing, photogrammetry was used to measure the geometric changes of the panels, including volume changes and panel cracking. These measurements were correlated with the load and displacement data, allowing visual observation to be related to the applied force and displacement. The test results provide a comparison of the mechanical performance of the various panel types and can assist in interpreting the condition of installed surface support. Visual assessment of the loading cycle and strength capacity of shotcrete in underground excavations will improve mine safety by providing a means to better quantify the stability of installed shotcrete support.

Jan 1, 2016

By H. Suharyono

The results of an experimental study of polymer-induced flocculation of clay suspensions in continuous, stirred-tank reactors are presented. The effects of polymer dosage, mixing time and mixing intensity are shown to be generally similar to those observed for equivalent batch systems, but flocculation appears to be generally less effective in the continuous process. Settling rates are lower and supernatant turbidities are higher for the continuous system. It is postulated that non-equilibrium effects due to simultaneous polymer adsorption and floc growth can be exploited so as to enhance flocculation in batch systems. The nature of the continuous process, however, offers less opportunity for taking advantage of such effects. Conditions in a continuous flocculation system inherently lead to a closer approach to equilibrium.

Jan 1, 1994

By Hugh McMillan

To protect the water supply for the Metropolitan Chicago area, the Illinois legislature, in 1889, created the Metropolitan Sanitary District of Greater Chicago. To insure the quality of the water supply, the Sanitary District collected and diverted the wastes of 750,000 people away from Lake Michigan. Today, the Sanitary District collects and treats the wastes from a domestic population of 5 ¼ million people and an industrial waste load equivalent to 4 ¼ million people. The District serves Chicago and 120 other cities and suburbs in an 858 square mile area. An average of 1300 million gallons of wastewater is treated each day, producing as a by- product about 700 dry tons of solids which contains more than $10,000 worth of plant nutrients when equated to the value of commercial fertilizer purchased in the retail market. The Sanitary District considered several alternatives to past methods for disposing of these solids, and chose land application as a technique to utilize the solids produced by the wastewater treatment process in a beneficial manner.

Jan 1, 1973

By J. Boisvert, E. Daniels, C. Deutsch

"INTRODUCTION Conventional mine planning is performed on a single resource model at a selective mining unit (SMU) scale deemed appropriate for the deposit and mining method. Estimation methods such as kriging and inverse distance, commonly used to construct a single model, are susceptible to histogram smoothing (Rossi & Deutsch, 2014). This can be mitigated by limiting the number of composites per estimate, therefore correctly reproducing the distribution of estimates (Boisvert & Deutsch, 2012). Search limiting techniques remedy histogram smoothing at the cost of introducing a problematic conditional bias (Isaaks, 1999) and introduces even greater spatial smoothing. Localization is an alternative, offering histogram reproduction through post processing of more robust probabilistic modeling techniques. A single localized model at the SMU scale is desirable. The correct histogram can be reproduced and a single model allows for the use of conventional mine planning and resource evaluation techniques. Despite the advertized benefits of localization, the necessary reliance on a larger panel scale as a middle step in the localization process yields unsightly “edge-effect” artifacts (Boisvert & Deutsch, 2012). Two approaches to artifact reduction are presented here. The first is a straight forward optimization approach designed to minimize an objective function that penalizes artifacts including panel edge discontinuities to generate a model free of panel edge-effects. The second approach redefines a panel in a less conventional fashion as a randomly chosen set of SMUs throughout the domain. This method produces a model void of any regular panel shape resulting in an artifact free model. Artifact reduction minimizes the obvious “edge-effect” issues of localization but local precision issues described by Boisvert & Deutsch (2012) persist. Localization is not a replacement for quantified uncertainty for comprehensive risk analysis and resource evaluation. LOCALIZATION Initially developed with Uniform Conditioning in mind, localization collapses a distribution of local uncertainty at a panel scale to an SMU scale model for mine planning (Abzalov, 2006). This process has been extended to Indicator Kriging (Hardke, 2011), Sequential Gaussian Simulation (Boisvert & Deutsch, 2012) and MultiGaussian Kriging (Daniels and Deutsch, 2014). The localization process is performed in a similar fashion regardless of which technique is chosen to create the prior model of uncertainty. Methodology There are three scales of importance considered in the localization process. The point scale, otherwise known as the data scale, is the smallest and is the scale at which experimental data is collected. The SMU or block scale is the familiar scale at which mine planning and resource evaluation takes place. Lastly, the panel scale is larger and contains a number of SMUs. Each of the three scales is illustrated in Figure 1."

Jan 1, 2015

Paper and paperboard manufacturers need to quantify the carbon footprint and environmental impact of their products to satisfy market, social and government demands. Coated paper products contain minerals, such as kaolin and calcium carbonate, at significant levels; some coated paper grades have mineral contents as high as 45% by weight. Some uncoated paper has no mineral content, but most uncoated paper contains some mineral to improve appearance, process efficiency and cost. Super-calendared paper grades can contain levels of mineral up to 35% by weight. This paper describes how to calculate the carbon footprint of kaolin and calcium carbonate minerals used for white pigments. The carbon footprint of these minerals strongly correlates to the primary energy sources, final product form and energy used to calcine kaolin and lime. Kaolin and calcium carbonate pigments have a favorable impact on the carbon footprint of paper and paperboard products by directly substituting for fiber and by reducing the energy needed for paper making. Key words: Kaolin, Calcium carbonate, Paper production, Carbon footprint, Lifecycle analysis

Jan 1, 2010