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By Ernesto Maldonado, Zach Agioutantis, Jesus Romero

Reliable prediction of dynamic deformations is important when planning to undermine important structures that cannot tolerate large relative deformations and or large horizontal strains. This paper presents examples of dynamic deformation profiles that include subsidence, horizontal displacements, and horizontal strain for a number of points over a retreating longwall panel in the eastern United States. The prediction points are located at different distances from the excavation rib and therefore present a different response in terms of dynamic movements. The formulation is based on the influence function method as implemented in the Surface Deformation Prediction System (SDPS). Results show that the subsidence development curve may be reliably predicted for surface points in the middle of the panel. However, in cases where points may be affected by the magnitude of the edge effect offset, subsidence predictions may be very conservative, that is, higher than actual movements.

Jul 1, 2023

By P. Anciaux, T. Simpson

The competitiveness of the EU manufacturing industry has come to the forefront of EU politics. The systematic monitoring of developments and the review of the state of the competitiveness of economies and enterprises was identified as an essential component in this process. Work is currently being carried out within Enterprise and Industry Directorate-General in order to analyse the different factors that influence the competitiveness of the non-energy extractive industry. Such an assessment should help to identify policies and actions which could contribute to and enhance the competitiveness of the industry. Assessing the competitiveness and sustainability of the industry implies the need for reliable, consistent data. One important example of how this need is being addressed, is the development of sustainable development indicators (SDI) for the EU non-energy extractive industry. These seek to monitor the industry’s performance and provide a platform for openness and discussion. Work was started on the development of SDIs in 2000, and the first report was published in February 2004.

Jan 1, 2005

By M. L. Sharrah

Communication about the energy problem has come at us in great profusion during the last couple of years--reports, speeches, editorials, advertisements--and events. Events such as the Arab embargo on oil exports which vividly demonstrated the world's dependence on oil, a finite and nonrenewable resource. And the three-fold increase in the price of oil which provides a constant reminder of the political and economic implications of dependence on foreign oil. A distinction among countries exists today which was almost inconsequential two years ago--the oil exporting nations and the oil consuming nations. The only rational way for the consuming countries to lessen the political and economic clout of the OPEC group is to reduce their dependence on oil. The United States is capable of playing a significant part in such a move for several reasons.

Jan 1, 1975

By Dean H. Herrick

The production of crushed stone in the United States has exceeded 1.0 Gtpy since 1987. Eighty percent of the crushed stone produced is used in the aggregate industry, accounting for over half of the quantity of natural aggregate consumed in the United States. Approximately 718 of the crushed stone produced in 1989 was limestone and dolomite followed by granite, traprock, sandstone and quartzite, miscellaneous stone, marble, shell, calcareous marl, volcanic cinder and scoria, and slate in order of descending volume (Table 1). Of the remaining 20% crushed stone produced in the United States and not used as aggregate, 12% is used in the manufacture of cement which is an important construction material. Only 8% of crushed stone is used in specialty products not associated with the construction industry. Therefore, this chapter will concentrate on crushed stone as used in aggregates, with occasional reference to other uses or to chapters which discuss specific nonconstruction uses of crushed stone. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass by the addition of cementing or binding materials that produce a concrete by compaction, or by natural weight to produce a road or foundation fill. Aggregates are usually from 80 to 100% of the material volume of the construction masses in which they are used. Conditions necessary for a rock deposit to be developed for construction crushed stone include: Quality-should pass rigid specifications for strength and durability; Quantity-adequate volume of rock is needed to have a production life of at least 10 years, preferably 20 or more years; Market-must have adequate market to support a new crushed stone operation; Transportation-transportation cost must be competitive for the intended market; Environmental-the impacts of mining, processing and transportation of crushed stone on the environment at or surrounding the mine site must be within acceptable limits; Permitability-mining, processing and transportation of crushed stone must usually be permitted by governing agency. The following discussion will touch upon all facets of crushed stone operations from the mineral deposit and its geology to technology, uses, economic factors and end with governmental regulations of mining crushed stone. The sections are not designed to answer all questions, but rather to be an introduction to the crushed stone industry. Where more information is required, The Aggregate Handbook by Barksdale (1991) is recommended as the best general source.

Jan 1, 1994

By R. Benito, J. Lopez, H. Gamarra

This article describes three practical applications of the Hill of Value (HoV) methodology within different stages of strategic planning for open-pit mining operations and projects. In the pursuit of optimal mine planning, this study establishes a comprehensive case study during the (i)design phase, by refining key parameters for efficient decisionmaking. (ii)production planning, where the HoV is used to define achievable production rates, enhancing operational effectiveness through a nuanced consideration of mining and processing capacities. (iii)Additionally, the study introduces a conceptual framework for orchestrating the optimal sequence of multiple pits during the planning phase, with a focus on maximizing project value.

Feb 1, 2024

By John E. Anderson, Charles A. III Cravotta, Eleanora I. Robbins, E. Terrance Slonecker, Gordon L. Nord

Remote sensing is being tested for its ability to identify the severity of impact on streams that are subjected to contaminated mine drainage (CMD) in the Southern Anthracite Coalfield of Pennsylvania. Airborne digital multispectral video images of acidic and near-neutral CMD are being compared with field spectra, water chemistry, mineralogy, and microbiology. Spectral differences in the visible region of the electromagnetic spectrum are caused by the presence of schwertmannite in the acidic precipitates and ferrihydrite in the near- neutral precipitates. The acidic CMD averages 1,500 mg/L sulfate and has bacteria coated with schwertmannite; the near-neutral CMD averages 87 mg/L sulfate and has bacteria coated with ferrihydrite.

Jan 1, 2000

By M. R. Fletcher

Slags generated by the ferrous-metals industry can be used to produce high-tech ceramic materials. The properties of these ceramics can be controlled by judicious choices of composition, additives, and processing parameters. Standard methods of materials handling, such as comminution and mixing, are as applicable to slag as to any other mineralogic raw material. In this study, foundry slag was ground, homogenized, melted and formed to produce a glass, and then heat treated to crystallize it into a high-strength glass-ceramic. The product shows promise as a low-cost wear-resistant tile material which can be custom cast. This and similar materials, made from slags and natural rocks, are candidates for use as construction materials, acid-resistant piping, shock-resistant sheathing, rot-proof pilings, and, when foamed, even as pontoons.

Jan 1, 1988

By David A. Newman

The Geomechanics Classification (Bieniawski, 1979) was modified for entry and roof support design in underground room-and-pillar coal mines. Adjustment multipliers were introduced to incorporate the influence of strata weatherability, high horizontal stresses, and the roof support reinforcement factor into the existing classification system. Sixty-two case histories of both standing and fallen mine roof were collected from two mines in the northern Appalachian coalfield. Twenty-seven engineering and geologic parameters were recorded for each case. A partial correlation analysis was carried out on the cases to establish which parameters have a significant impact upon the supported stand-up time of coal mine roof. Survival analysis, a statistical technique used in medical research to assess the effect of a drug or treatment on a patient's life expectancy, was conducted together with stepwise multiple regression to derive values for the adjustment multipliers. A practical example is included to illustrate the application of the modified Geomechanics Classification to underground coal mine design.

Jan 1, 1985

By R. L. Miller

Two samples of iron enriched basalt (IEB) containing simulated nuclear fuel and having two distinct microstructures were prepared and tested for uranium recovery. The IEBs are refractory towards leaching by ground water. However, the uranium content (15.8%) is high enough that if aggressive leaching techniques are used for uranium recovery, these materials could be considered as man-made uranium ores. The IEBs discussed in this report were prepared to simulate Three Mile Island-2 core debris. The crushed IEBs were treated using three different methods simulating potential industrial scale processes. In one method the IEBs were fused with sodium hydroxide then the cooled mass leached first with water then with dilute sulfuric acid; about 52% of the uranium was recovered in this case. In the second method the IEBs were treated with a sulfuric acid/hydrogen peroxide lixiviant and about 13% of the uranium was recovered. In the third technique the IEBs were leached with a sodium carbonate/sodium bicarbonate/hydrogen peroxide solution. Only about 0.1% of the uranium was recovered. The results of these screening tests suggest that the IEBs can be successfully treated for recovery of the contained uranium. Other studies would be required to determine if other values, such as zirconium or silver, could be recovered from the IEBs.

Jan 1, 1984

By K. S. Venkataraman

The physical properties of clay-water systems depend on the complicated system of forces between the clay particles themselves, and between the clay particles and the ions in the liquid phase. The kind and distribution of ions in, on, and between the clay particles and the size and the shape of the particles are the basic factors determining the macroscopic behavior of clay-water systems. Understanding the system requires a knowledge of the nature of the clay particles, their size, structure, composition, and surface properties, and of the manner in which they interact with ions [and molecules] in the surrounding liquid [or other medium]. The validity of Professor Brindley's words (Brindley, 1958), written three decades ago in the context of making pottery, whitewares, and electrical porcelains, transcends time, and the basic message is perhaps all the more important in the considerably expanded use of ceramics for structural, thermal, tribological, electronic, and other applications. Silicon carbide, silicon nitride, and sialons have been studied in the last two decades for high- temperature structural and tribological applications, particularly for using in internal combustion engines. Titanates, zirconates and niobates of barium, strontium and lead, have high dielectric constants, and are extensively used in the formulations for making capacitors. Hexagonal ferrites (molecular formula MO.6Fe2O3) are in use for making permanent magnets for fabricating miniature motors, and for assembling loud speakers, particle accelerators etc. Cubic ferrites such as magnesium-zinc ferrite and nickel-zinc ferrite are used as transformer cores, and for other high-frequency applications. In this context, Richerson's recent book (Richerson, 1984) on the general scope of traditional and technical ceramics is a good starting point for an overview of contemporary ceramics technology. Glasses are a whole class of amorphous materials used widely as sintering aids, and for making glass-bonded ceramics and glass-ceramic composites. Composites are yet another burgeoning field where two or more particulate components are used for improving the performance of ceramics. For all these applications, the inorganic starting materials are almost always submicron and near-micron powders. Understanding the powders' physicochemical properties, and their surface chemical interactions with the surrounding liquid/gaseous medium is-necessary for making reliable ceramic parts at competitive prices. Even though ceramics science and engineering has attained its separate identity in universities and the industry, ceramists themselves would concede that ceramics science is a cross-disciplinary field, having incorporated and assimilated within itself many principles from several apparently disjointed disciplines. Principles of material science, graduate-level physics and chemistry, polymer science, surface and colloid chemistry, transport phenomena, particle technology, unit operations commonly used in chemical engineering and mineral processing, and statistics and applied mathematics are integral part of any ceramics curriculum in universities. Added to this is the fact that all bench-scale successes in making ceramic parts are to be scaled-up for larger throughput operations. Understanding and applying process engineering principles of comminution, classification, drying, calcination, etc. then becomes essential. CERAMIC FORMING: Despite the diversity of the materials and processes, conceptually, the steps involved in making ceramic parts have remained the same over several decades: The different components for making the pan (usually one or more powders plus other forming and sintering additives) are proportioned and mixed thoroughly, and the well-mixed formulations are consolidated into desirable shapes known as "green bodies." Usually binders such as wax, clay, organic polymers and surfactants, whether dispersed or dissolved in a suitable liquid are used during mixing the batch for giving strength for the green bodies. In the dried green state, the inorganic powders typically occupy only 55 to 60% of the bulk volume of the body, depending on the particle size distributions of the powders and the forming history, with mostly inter- particle voids accounting for the rest of the void volume. SINTERING: The formed bodies are then fired in high- temperatures kilns/furnaces during which the parts are exposed to a predetermined temperature profile, and "soaked" for a certain duration at the final high temperatures, typically between 1200 K and 1900 K, and then cooled to room temperature. The gaseous atmosphere in the furnace is controlled (oxidizing, reducing, or inert) when necessary. During the initial stages of firing, volatile liquids evaporate, and during the intermediate temperatures between 400 and 600 K, the the organic polymeric additives pyrolize and oxidize into water vapor, CO, C02, and other gases. At still high temperature, the glasses, when present, soften, and simultaneously, the ceramic particles rearrange into a network of grains with definite grain boundaries so as to reduce the total interfacial free

Jan 1, 1990

By Clayton Vernon Deutsch, Marcel Antônio Arcari Bassani, João Felipe Coimbra Leite Costa, Vanessa Cerqueira Koppe, Pedro Henrique Alves Campos

Traditional linear approaches oversimplify the complexities of ore blending. Adopting nonlinear blending models in mining and mineral processing is critical to enhancing prediction accuracy and allowing optimization regarding nonadditive variables, such as metallurgical recovery. This study implements a simulated annealing algorithm in short-term mine planning that seeks to optimize the metal recovery by considering how to blend the ore in the mine better. Two nonlinear metallurgical recovery models are used as inputs to the algorithm to represent synergistic and antagonistic blending. The results of the case study demonstrate that the optimized schedule exhibits improvements in both blending behaviors when contrasted with conventional linear-based scheduling plans.

Jan 1, 2025

By J. Abbott

This paper gives a brief description of the Compania Ninera del Pacifico (CNP) a subsidiary of the Campania Acero del Pacifico (CAP), its participation in the Chilean Iron Ore mining and the gradual development of its activities. mainly in this paper, it is explained the CNP experience in the production of 34 million tons of self-fluxing pellets for Blast Furnace in a period of ten years in its Huasco Pellets Plant.

Jan 1, 1989

By V. R. Degner

Development of large mechanical flotation machines during the past fifteen years. This success was a contributing factor in recognizing the value in a systematic and rational means of optimizing the flotation circuit, where the preferred circuit arrangement is based on both economic and metallurgical performance considerations applied to a relatively small number of flotation machines. Flotation kinetics and effective pulp residence time models have been incorporated into a computer program, described in this paper, which has proven to be an effective analytical tool to quantitatively relate flotation process parameters, such as feed tonnage and grade, solids concentration, and reagent strategy, to flotation circuit arrangement, machine size and operating condition.

Jan 1, 1993

By Naomi H. Harley, Daryl E. Bohning, Isabel M. Fisenne

INTRODUCTION Underground mines in many parts of the world have elevated levels of short-lived 222Rn daughters. Lung cancer implicating exposure to short-lived daughters is documented in the U.S., Czechoslovakia, Canada, Sweden, the U.K., France and Newfoundland. An elevated lung cancer mortality (in excess of that expected) has been observed when cumulative exposure to alpha emitting short-lived 222Rn daughters (218Po, 214pb 214Bi 214Po) is greater than about 60 working level months (WLM) [1]/ (Hewett, D. 1979). This is equal to an absorbed alpha dose of about 30 rads to shallow basal cells in bronchial epithelium. Long-lived alpha emitters are also present in underground mines, and especially uranium mines because of airborne particulates containing uranium. The 238U parent of this primordial series supports other long-lived emitters 234U 230Th, 226Ra, Pb(210Po) which are in some degree of radioactive equilibrium with the parent 238U. Airborne particulates can be present due to drilling on the face of the ore body as well as in all parts of the mine through resuspension from the mine floor. Particles from 1 µm to about 5 µm penetrate the nose with reasonable efficiency and deposit primarily in the tracheobronchial tree. They are removed by ciliary motion (the bronchial escalator) but deliver an alpha dose to basal cells in bronchial epithelium during clearance in the same manner as short-lived 222Rn daughters. It is the purpose of this work to indicate the alpha dose to basal cells in bronchial epithelium delivered by the long-lived emitters 234, 238U. The dose calculations reported here based upon a few measured values of these isotopes in air in uranium mines in New Mexico and Colorado. MEASURED 234, 238U IN URANIUM MINE ATMOSPHERES In 1979, the U.S. Bureau of Mines undertook a study to evaluate personal monitors to be worn by miners to measure short-lived 222Rn daughters. One of these devices sampled air at 100 cm3/min through a 13 mm glass fiber filter, with a small pump worn on the belt. Alpha particles emitted by 222Rn daughters on the filter were measured continuously by a thermoluminescent dosimeter (TLD) chip. Each monitor was worn by a miner for a 170 hour working month and approximately one cubic meter of air was sampled during this period. Six different mines were selected for the test in New Mexico and Colorado. The mines used either wet or dry drilling methods. Miners in each location were equipped with the personal monitors. Subsequent to their use in evaluating the shortlived daughters, Dr. Robert Droullard of the Bureau generously gave us these filter samples along with a few blank glass fiber filters from the same box of filters used in the study so that long-lived emitters present in these mine atmospheres could be determined radiochemically. Four of the samples have been run for 234, 238U. The radiochemical procedure for uranium is adapted from USDOE, Environmental Measurements Laboratory Manual (Harley, J.H., 1976). Briefly, the samples were placed in platinum crucibles, spiked with 232U tracer and pretreated with nitric and hydrofluoric acid. The residue was fused with potassium fluoride to transpose to pyrosulfate. The fused cake was dissolved in 7 [N] hydrochloric acid and the solution passed through an anion exchange column to isolate uranium. Iron was removed using mercury cathode electrolysis. Uranium was electrodeposited onto platinum dies and counted using solid-state alpha spectrometry. The samples from each type of mine (wet and dry) were analyzed. The samples in the "wet" mine in New Mexico were selected on the basis of the original TLD measurement because they were near the maximum occupational standard for radon daughters. These samples should also represent upper limits to longlived activity encountered, since they were obtained at drilling operations on the face of the ore body. Samples collected in the "dry" mine in Colorado were pot associated with a particular location in the mine and should be representative of a month long overall exposure in many locations and operations. The values are shown in Table 1. The two uranium isotopes are in equilibrium and their alpha activity

Jan 1, 1981

By Dan Nilsson

Rock from underground mining has a size-distribution, that varies from mine to mine, depends on rock conditions and mining method and on how much explosives etc, that is used. Because at the high costs, associated with full-scale studies of the size-distribution of blasted rock in a mine, detailed information is seldom published about such size-distributions. However, some facts can be noticed. Rock from tunnelling and other types of development work has a fine fragmentation. Cut-and- fill mining is a method that normally results in blasted rock with an advantageous size distribution. Block caving on the other hand often results in large amounts of boulders, since blasting of the rock is normally not used.

Jan 1, 1985

By C. V. Deutsch, J. B. Boisvert, M. A. Cuba

The amount of information available for characterizing a deposit increases over time due to the continuous acquisition of data during mining. This additional information is collected from different sources, including geologic mapping, production data and infill drilling. Throughout the lifetime of a mining project, the block model and the mining sequence are periodically updated to account for this new data. In general, the acquisition of additional data increases the accuracy of the block model, reduces uncertainty in ore/waste limits and clarifies the optimal mining sequence. There has been extensive research on mine planning, but current techniques do not consider the decrease in uncertainty as additional information becomes available. Conventional paradigms assume either 1) the kriged model is correct and uncertainty due to multiple realizations does not change the mining sequence, or 2) the mining sequence is unrealistically adapted to each realization. A new paradigm is proposed for evaluating minable reserves of surface mining projects, which accounts for the acquisition of additional information in the design of the long term mine plan. Multiple scenarios characterizing the dynamic nature of mining and data collection are created. In the proposed methodology, the performance of the long-term mine plan depends on both mining and data acquisition strategies. Each scenario considers the same extracted volume for the first period, resulting in a set of scenarios that diverge from a common initial period, accounting for how the mine may develop over time as new data are acquired and provide a more realistic evaluation of reserves with an appropriate level of uncertainty. A synthetic example is presented to illustrate the implementation of the methodology and the benefits over conventional paradigms.

Jan 1, 2013

By Y. Ye, J. D. Miller

Certain bituminous coals are known to contain appreciable quantities of natural fossil or subfossil resin. Such resinous coals are found in the western US, particularly the Wasatch Plateau coalfield of UT. Some of the seams in this field contain an average of 5% resin. This fossil resin has been recovered by gravity and/or flotation processes since 1929. Resin concentrates thus produced are of low quality and are usually refined by solvent extraction. The purified resins are of commercial importance in the adhesive, coating, rubber. and ink industries, etc. An improved flotation technique has been developed which involves ozone conditioning to selectively float resin from high-volatile bituminous coal. With this flotation process, a concentrate product which contains 95%

Jan 1, 1990

By K. E. Hjelmstad

Solution mining operations often encounter difficulty maintaining adequate leach solution flow into the ore formation because of loss of formation permeability near the injection well. Permeability loss caused by swelling and breakup of clays and fine particle migration can often be the cause of the problem. Combined permeability and leaching tests were done in the laboratory on samples of clay bearing ores to evaluate a clay-stabilizing polymer's effectiveness in preventing the problem. Test results indicate that treating the ores with cationic polymers could maintain permeabilities two to five times greater than the long-term permeabilities present in untreated ores. Both alkaline (pH 8.5) and acidic (pH 2.0) leaches were used in the permeability leaching tests. To determine the reasons for the success of the clay stabilizing polymer, clay swelling tests and zeta potential measurements were made on untreated ore samples and on ore samples treated with the cationic polymer. Test results indicate the cationic polymer could reduce the degree of negative charge on fine particles and their tendency to disperse, as well as reduce clay swelling. Test results indicate a potentially beneficial effect on operating parameters such as capacity and injection pressure during leaching, if clays and fines are kept stabilized. This may be done by treating the zone of high fluid velocity near injection wells with cationic polymers.

Jan 1, 1991

By Anthony G. Fonseca

About 45% to 50% of the coal mined in the United States passes through coal preparation plants. East of the Mississippi River, this number increases to about 75% to 80%. Although the cost for coal preparation is worthwhile to some, the coal industry faces the challenges of continuing downward pressure on the price of coal and the impact of new environmental regulations. Coal preparation is an effective process that achieves 75% to 80% ash reduction, 15% to 80% trace element reduction and 85% to 90% Btu recovery. It is less effective for pyrite reduction (35% to 70%) and on-line operating time (40% to 60%). It also suffers from obsolete control systems. In coal preparation, raw coal is modified to a more preferred form to enable its use. The methods used to achieve this modification must be cost-effective and appropriate to the raw coal, the scale of production and the end-user requirements.

Jan 1, 1995

By Jue Kou, Fazhao Sun, Jiang Liu, Cuili Gui, Baoqiang Yu, Chunbao Sun

A novel special magnetic separator was developed based on the special properties of precious metal-bearing alloy in highgrade nickel matte. The recovery of Au, Pt, and Pd was 77.79%, 84.79%, and 81.79% respectively at optimum operation conditions of magnetic separator feed of 2.5t/h, pulp density of 45%, and flush water of 1.5t/h, and the recovery significantly improved comparing with normal magnetic separator. Magnetic field simulation of the special magnetic separator indicates that magnetic intensity of 0.6 T can be generated on the surface of magnetic drum, which can strengthen the recovery of heavy alloy that contains precious metals. The alternate strong and weak magnetic field can also make magnetic particles rolling on the surface of drum, which will reduce the generation of magnetic agglomeration to a large extent and decrease the content of impurities in magnetic concentrate.

Jun 16, 2022