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By K. Kavouridis

The energy and climate protection policy of European Union (EU), and its Member States adopted in 2007 bridges security of supply, environmental protection and competitiveness. The objectives of the EU energy and environmental strategy cover the foreseeable period till 2020. It assumes all sources of energy will be needed. The objectives for renewable and improved efficiency are ambitious; it must be established if they are also realistic. Coal can continue to make valuable contribution to the security of supply and low price of electricity, only with technologies allowing for drastic reduction of the CO2 emitted of its combustion. The aimed at -20% reduction of green-house gases (GHG) of EU-27 by 2020 is an objective limited in time and content. Europe produces less than 15% of global CO2 and this will be reduced to 10% in 2030. Emissions Trading (ET) is to remain the central instrument for CO2 management, especially in the power sector. ET scheme (ETS) or other mechanisms need designing to create an incentive for investment in higher efficiency and technologies and to Carbon Capture & Storage (CCS). The ETS as the climate protection instrument of the EU can become a heavy burden (high fuel and electricity prices, less security of supply) or it can create a climate for modernization of fossil fuel power plants. The suggestion in this paper of fuel-specific benchmark system for CO2 allocation after 2012 can combine the emission levels to be reached with a strong drive to invest, the necessary investment security, transparency and the principle of proportionality. A Benchmark System as recommended by coal industry could adapt to the different circumstances in the long term and comply with EU energy and environmental policy objectives.

Jan 1, 2008

By C. R. Hairfield

With ever rising energy costs, it is increasingly important for mines to operate with energy efficiency. As a large portion of a mine?s energy consumption is often attributed to the operation of mine ventilation fans, maintaining an efficient ventilation system is a critical pro-active way for mining companies to reduce power costs. A common way to measure a mine?s ventilation system efficiency is to calculate the volumetric efficiency, which is simply a calculation of the percentage of total mine air that is usefully employed for production. The purpose of this study is to document a nationwide comparison of the volumetric efficiency of U.S. underground coal mining operations. The results will aim to show just how efficient today?s coal mine ventilation systems are and what factors may be causing their various efficiencies and inefficiencies.

Jan 1, 2009

By Wm. I. Weisman

Sometimes in assessing where we are and where we are going it is informative to take a look at where we have been. Whether or not it adds to our understanding of the present, I think it may be interesting to review some of the past history of our industry. As a starting point I chose to use the famous Paley Commission Report, formally known as "The U. S. President's materials Policy Commission -Resources for Freedom."(l) The Paley Commission report said "Fluorspar is an essential raw material for the steel, aluminum, and chemical industries." Of course this statement is still true. It also said, "United States known reserves of fluorspar would be sufficient for some 15 years at present rates of consumption--about 426 000 short tons in 1960. Projected consumption for 1975, however, is several times as great, and reserves in other free countries do not appear adequate to supply United States deficiencies during the next 25 years." This simply demonstrates how even the most learned and competent people can observe all the facts avail-able to them at a given time and yet be unable to predict the future very accurately. We all know that reserves in other countries are more than adequate to supply the United States today, 25 years since the report was published. In fact, the report estimated free-world reserves at something over 36 million tonnes (40 million short tons). Contrast this with 246 million tonnes (271 million short tons) estimated as total world reserves from the section on fluorspar from Commodity Data Summaries of 1974, published by the Department of the Interior. (2) The Paley Report discusses other matters pertaining to fluorspar that are still of interest, such as improving mining methods. Furthermore, it certainly did a good forecasting job in noting that greater recycling should become possible in the aluminum industry in regard to fluorine lost in wastes and also concerning the substitution of fluorspar in the steel industry by other fluxing materials. It also suggested that non-fluorine containing propellants should be investigated as a replacement of those containing fluorine as a conservation matter. Some discussion was devoted to recovering the fluorine content of phosphate rock, which is being practiced today, but was in its infancy in 1950.

Jan 1, 1978

By F. M. Doyle

Metal removal kinetics and metal ion selectivity in ion flotation were studied from a thermodynamic perspective. Surface tension data could be used with the Gibbs adsorption equation to quantitatively predict the metal-ion removal kinetics in alkylsulfate-Cu systems. However, surface tensions predicted cation selectivity coefficients in the sodium dodecylsulfate (SDS)-Cu-Ca and SDS-Cu-Pb systems rather poorly, although the predicted order of the selectivity (Cu2+ < Ca2+ < Pb2+) was correct. Another thermodynamic selectivity model, which used the Grahame adsorption equation and a geometrical analysis, predicted cation selectivity coefficients that agreed very well with experimentally measured values.

Jan 1, 2002

By H. Savasci, G. Yarim, J. S. Chung

As part of ongoing deep-ocean mining research, hydraulic transport systems as well as status of deep-ocean mining systems are reviewed in the aspects of manganese nodules and crusts from 8006,000-m depth. The emphasis of the investigation of hydraulic transport is placed on the shape effect of particles on the pressure gradients and flowrates. Series of tests are being conducted to study the lift characteristics of a 2-phasevertically upward hydraulic transport of 2 types of small solid particles in a PVC pipe of 1-in (2.54 cm) diameter: irregular-shaped silica sands and equivalent spherical glass beads. Pressure drops and mass as well asvolumetric flow rates were measured by electromagnetic(EM) flowmeter and mass flowmeter. The particle sizes used are 8-10 mesh. The results in turbulent flow range of 101045Re show that pressure gradients or friction factors are smaller for the spherical beads than the sands. The larger the concentration of the particles are, the larger the pressure gradients become. The larger the particle concentration is, the less the effect of particle shape on pressure gradients becomes. The shape effect is greater for the minimum particle transport velocities than for the settling velocities.

Jan 1, 1999

By Myron W. Mellor

Our efforts at McNally, to find a better way to mechanically separate particles from liquid in a slurry have led to the development of two new centrifuges. The first unit utilizes a slotted opening screen as the filter media and retains all plus 200 Mesh and most of the 200 by 300 Mesh particles. The second unit is a solid bowl centrifuge with a novel method of removing the solids and delivers an effluent containing as little as 300 PPM solids in suspension. The first unit was designed to separate particles in the range of about 1 MM x 0 or smaller top size from the liquid slurry and produce solids having low surface moisture content, and a liquid concentrate containing a low percentage of solids. A prototype of this unit has been in the field undergoing tests for over two years. A few of these test results are shown in Tables I & 11. Testing has been mostly limited to the field of coal, how- ever this does not mean that the machine would accept only coal slurries. The machine has produced a dewatered product having as low as 5.5% surface moisture, and an effluent containing as low as 1.4% solids and handled slurries containing from 15 to 50% solids by weight.

Jan 1, 1975

By B. Oraee

Tunnels as any other structures are affected by different loads and stresses. Generally, the loads on tunnels consist of both static and dynamic loads. These loads must both be considered in the tunnel design process. In this paper, the stability state of Jiroft water-transform tunnel is evaluated. Firstly, the in-situ stresses and then using Kirsch?s equations the induced stresses due to static loads in walls and crown of tunnel are calculated. Consequently, the strain caused by probable earthquake without considering the interaction between the concrete lining of tunnel and rock mass using seismic analysis is calculated based on free-field deformation. When the strain is determined, the simplified method of closed-form solution, Wang?s equations and Penzien?s equations are used to estimate the applied forces on the tunnel due to earthquake such as axial force and bending moment on a tunnel section taking into account the interaction of the tunnel concrete lining and rock mass. Results of this study show that the loads applied to the tunnel as a result of earthquake waves can be affect the stability of underground structures, especially long structures such as tunnels.

Jan 1, 2011

By Jesus M. Rohena

Concrete pipes and small boxes have been installed by the jacking method. This paper will describe a recent project were large concrete boxes were installed by the jacking method. This project is in the city of Boston, MA. By now everyone in the USA knows something about this project. The project official name is The Central Artery/Tunnel Project (CA/T). This is the biggest public work project in the USA right now, with an estimated construction cost of 14 billions. The main objective of the CA/T project is to replace an existing artery built in the 1950s to increase capacity and safety. One section of the new artery will cross under several railroad tracks near the South Station. To construct the section of the new artery under these tracks, big concrete boxes were installed by the jacking method. The jacking method can be used to install pipes, small concrete boxes, and the CA/T project has demonstrated that big concrete road tunnel boxes can be installed by jacking.

Jan 1, 2003

By G. W. Luxbacher

With the advent of acid rain legislation included within the Clean Air Act Amendments of 1990, a great deal of uncertainty with regard to price, source and production quantities has been cast into the coal market. Powder River Basin and other western coals continue a rapidly accelerating migration eastward, South American coals move into the northern markets, states propose legislation to assist utilities in complying with the new regulations in hopes of maintaining their own coal industries, while some utilities question the long term availability of eastern compliance coal. Any major coal producer must make decisions now to assure their continuing presence in the market place; several companies have adopted a strategy to acquire eastern compliance reserves while others have invested in technology to compete as a low cost producer. This paper discusses some of these options in light of the uncertainties of the market place, from an eastern coal producer?s viewpoint.

Jan 1, 1992

By Richard R. Klimpel, Basil F. Fee

This paper summarizes the status of a series of new chemical reagents developed with the explicit goal of expanding the capabilities of existing froth flotation processes as well as allowing for new solid/solid separations to be undertaken that are not now feasible with flotation. The first portion of the paper briefly outlines the theory and motivation behind the development of each new reagent family. &apos;The second portion of the paper deals with specific laboratory examples of some separation systems studied to date.

Jan 1, 1993

By S. C. Sun

A study(1) on the sulfuric acid extraction of alumina from some Pennsylvania ferruginous clays indicated that the published electrolytic method(2)(3) seems to be more efficient than the known chemical methods (4-9) for removing iron from the leach liquor. The main disadvantages of the chemical methods are the consumption of excessive amounts of reagents and/or the precipitation of prohibitive amounts of aluminum. In the electrolytic method, iron is deposited on the mercury cathode, while aluminum is not and remains in solution. This method, however, had been handicapped by the lack of an effective and economical way to purify the contaminated mercury cathode.(7)(l0). Described herein is a scheme for cleaning the mercury cathode, and for recycling the clean mercury back into the electrolytic cell. Armed with such an apparatus, the effects of applied potential, temperature, and operation time on the electrolytic separation of iron from aluminum sulfate solutions were determined. For the sake of comparing results, a term, removability, was coined to represent the percentage of iron amalgamated per unit height of electrolyte (cm.), per unit surface area of cathode (cm.2), per unit of operation time (second).

Jan 1, 1968

By C. Haycocks

In spite of the increasingly high capital investment required for longwall mining equipment, there continues to be a steady trend towards this form of mining. This move is caused in large part by improved productivity of longwall mining systems combined with greater percentage of coal recovered over room and pillar mining, reduced manpower requirements, and the inherent safety of the system. Longwall mining is most amenable to the greater depths experienced by many mining operations, particularly in the coalfields of the Eastern United States. Two primary problems in the installation of a longwall panel are determining whether a particular seam is suitable for longwall and, secondly, type and capacity of equipment required for such a mining operation. In addition, recent legislation has forced an evaluation of the surface effects of longwall mining with a view to determining what, if any, surface damage might result from extracting any particular panel. These factors must be determined using large and often complex quantities of geological, structural, mining, and surface data. This makes the problem most attractive to solution using the computer.

Jan 1, 1979

By P. Venkatraman, F. S. Knoll, W. S. Kow

Froth flotation is the most widely used technique for cleaning fine coal. This practice may change, however, with the development of enhanced gravity concentrators such as the Mozley Multi- Gravity Separator (MGS). The MGS is a flowing-film concentrator that utilizes centrifugal forces to improve the separation of flotation-size particles. In the present work, a pilot-scale test program was conducted to examine the effects of feed rate, feed solids content, wash water flow rate and drum rotation speed on the performance of the MGS. The test results indicate that the MGS effectively rejects high-density minerals such as pyrite, while ultrafine ash-forming minerals are removed less efficiently. A major advantage of the MGS is that high separation efficiencies can be realized without additional grinding, flotation reagents or heavy media. This article describes the working principles of the MGS and presents data obtained from recent pilot-scale test work.

Jan 1, 1995

By Donald E. Hulse

Selection of a block size for a computerized 3 dimensional ore body model is an exercise in compromises. Larger blocks decrease the use of computer resources and decrease the variance of the block estimates. Smaller blocks increase the resolution of the model and the selectivity which can be used in the planning, but increase the variance of estimates in the individual blocks. A common rule is that blocks can be as small as one fourth the average sample spacing, however this ignores the interrelationship between the block size, the sample spacing, and the variogram model. This paper will explore this relationship Kriging estimation variance will be used as a comparative measure of estimate quality. Graphical techniques will be used to show that there is a point where smaller block sizes cease to contribute to the resolution of the model. A method of evaluating the consequences of block size decisions will be examined.

Jan 1, 1992

By G. T. Lineberry, R. S. Mateer

Often only after years of "technical dormancy" do errors in published literature become apparent and meaningful. To prevent duplication of effort for future generations, the following corrections are offered. These errors were discovered during a recent study in which a computer program for mine hoist rope selection was developed (Lineberry and Mateer, 1988). In order of increasing gravity: Captions for Figs. 3 and 4 are transposed. Purported to be a more accurate method of rope selection than the process of successive approximation, the direct method assumes linearity between a given rope&apos;s minimum breaking strength, T, and unit rope weight, WV. Because of the sensitive location of the constant, K, in equation (8) for breaking strength, the significance of this nonlinearity is magnified. For a typical 6 x 37 class fiber core wire rope (Wire Rope Corp. of America, 1985), K actually varies from 43,650 to 52,190, depending upon rope diameter. Although the direct solution permits a rapid selection of hoist rope, an indirect (iterative) solution procedure is favored because of its improved accuracy and ease of computerization. Equation (8) for minimum breaking strength is in error. It should read:

Jan 1, 1990

By G. T. Lineberry, R. S. Mateer

Often only after years of "technical dormancy" do errors in published literature become apparent and meaningful. To prevent duplication of effort for future generations, the fol¬lowing corrections are offered. These errors were discovered during a recent study in which a computer program for mine hoist rope selection was developed (Lineberry and Mateer, 1988). In order of increasing gravity: Captions for Figs. 3 and 4 are transposed. • Purported to be a more accurate method of rope selection than the process of successive approximation, the direct method assumes linearity between a given rope&apos;s minimum breaking strength, T, and unit rope weight, Wv. Because of the sensitive location of the constant, K, in equation (8) for breaking strength, the significance of this nonlinearity is magnified. For a typical 6 x 37 class fiber core wire rope (Wire Rope Corp. of America, 1985), K actually varies from 43,650 to 52,190, depending upon rope diameter. Although the direct solution permits a rapid selection of hoist rope, an indirect (iterative) solution procedure is favored because of its im¬proved accuracy and ease of computerization. • Equation (8) for minimum breaking strength is in error. It should read:

Jan 1, 1989

By J. Kang

Supercritical fluid extraction (SFE) has became an attractive alternative technology to be a new process to recover metal, of which can be substitute the existing Leaching/Solvent extraction processes. Solvent extraction of metallic ions is a technically important and also well-established process that is used in the chemical and hydrometallurgical industries.1 Solvent extraction techniques use the chelation of metallic ions dissolved in liquid solution with organic ligands. Conventional solvent-extraction technique needs large amount of organic solvents and often creates environmental problems.2 More environment-friendly technology is needed nowadays, and there have been increasing attentions to extract metal ions by SFE. CO2 becomes one of the most notable alternative organic solvents due to its nonflammable, nontoxic, nonpolluting, and relatively inexpensive properties with its moderate critical point (73.8 bar, 31.06 °C). Many works have been reported in metal extraction under the supercritical CO2 (scCO2) solvent.3-5 In this study, to recover cobalt from wastes especially from spent lithium ion battery scrap, we selected two ligands ? Cyanex 272 and DEA (diethylamine) for the metal extraction in scCO2. Cyanex 272 is a commercially available extractant along with its series, Cyanex 301 and Cyanex 302. Smart and coauthors measured the metal extracting abilities of these three extractants, and found that Cyanex 301 and Cyanex 302 extracted metal ions much better than Cyanex 272 in the scCO2 solvent.10 The pH of water contacted with high pressure CO2 (70-200 bar, 25-70 oC) is about 2.8-2.95 based on the calculation and the measurement.6-7 Cyanex 272 is known to be less effective as a metal extractant in this low pH environment compared with other Cyanex series. However, when DEA is added to metal extraction reaction with Cyanex-272, DEA works as a strong base to Cyanex 272 converting Cyanex 272 to a deprotonated form (Figure 1), which results in an easy formation of metal complex and the enhanced extraction rate of metal ion.8 Therefore, the purpose of this paper is the metal extraction from spent lithium ion battery waste using scCO2 with Cyanex 272 and DEA.

Jan 1, 2010

By Leo Langland

One of the primary functions of the Geotechnical Services-Materials section of the Arizona Department of Transportation (ADOT) is locating, sampling, and evaluating potential aggregate deposits throughout the State. This information is essential in designing, estimating, and bidding highway construction projects. The nature of materials used for aggregate varies greatly within Arizona. The northeastern or plateau section is famous for its scenic sedimentary formations that are, how- ever, too soft to make suitable aggregate. Volcanic materials are widely used in place of more conventional geologic units. In contrast, the southwestern, or Basin-and-Range section, contains a relative abundance of good aggregate, especially a diversity of gravels. The paper will review the off ice, field, and laboratory methods used by the ADOT Materials Section in satisfying its needs for aggregate information in Arizona.

Jan 1, 1987

By Donald S. Bubar

The Separation Rapids property, located approximately 60 km (37 miles) north of Kenora, Ontario, Canada, is host to one of the largest rare metal pegmatite deposits in the world. This pegmatite was named the Big Whopper by its discoverer, Dr. Fred Breaks of the Ontario Geological Survey, because of the exceptional length and width of the surface exposure. The property is readily accessible from a main, all-weather road via a network of secondary logging roads. The main line of the Canadian National Railway passes through the village of Redditt, just 40 km (24 miles) south of the property. The Big Whopper is one of the complex-type (petalite sub-type) class of rare metal pegmatites that are geochemically the most highly evolved in the spectrum of granitic pegmatites. Such deposits are economically important as resources for the rare metals lithium, tantalum, cesium, and rubidium. While complex-type pegmatites are found in many areas of the world, most are too small to be profitably mined, however, with an inferred resource in excess of 15 million metric tons (mt) (17 million short tons [st]), the Big Whopper is only the fourth deposit of its type in the world with the size required to be of major economic importance. The other three deposits, which are currently in production, are the Tanco mine in Manitoba, the Bikita mine in Zimbabwe, and the Greenbushes mine in Western Australia. The Big Whopper is situated in the eastern continuation of the Archean Bird River greenstone belt which also hosts the Tanco pegmatite, approximately 60 km (37 miles) to the west. The principal commodities identified in the portions of the Big Whopper pegmatite explored to date are petalite (LiAlSi4010) and rubidium-rich K-feldspar. These are industrial minerals with important applications in the glass and ceramics industries. The Big Whopper also contains substantial quantities of lepidolite, a lithium, rubidium-mica which is the principal ore mineral for rubidium metal. Tantalum and cesium occur in anomalous levels with the petalite mineralization, and the possibility of finding zones of high enrichment in these valuable high-tech metals elsewhere in the deposit is excellent. Such enriched zones are typical of pegmatites as highly evolved as the Big Whopper. To date, the geological mapping and diamond drilling work completed by Avalon have delineated the Big Whopper pegmatite system over a strike length exceeding 1.5 km (0.9 miles), over widths ranging from 10 m to 80 m (30 feet to 260 feet) in thickness, and to a vertical depth of close to 300 m (1,000 feet), where it remains open. The pegmatite system consists of a vertically oriented massive petalite pegmatite dyke striking 280 degrees that is flanked by amphibolites containing a swarm of narrower albite and petalite dykes which have all undergone intense deformation in a high strain zone resulting in folding and intense shearing. The Big Whopper exhibits a mineralogical zonation pattern which is complicated by the superimposed deformation that has both folded and stretched the deposit. Drilling has defined a dilute geological resource totaling 7.1 million mt (7.8 million st) grading 1.283 percent Li20, 0.346 percent Rb20, and .007 percent Ta205 over a strike length of 600 m (2,000 feet), and to a vertical depth of 250 m (820 feet), where it remains open. The petalite and rubidium-rich-K-feldspars contained in the Big Whopper all appear to be of superior quality. The grades are consistent with a petalite content averaging 25-30 percent and a rubidium-rich-K feldspar content averaging 15-20 percent. The remainder of the rock consists mainly of albite, several types of mica, and quartz. Accessory minerals include columbitetantalite, cassiterite, apatite, garnet, and gahnite. Market studies show that the deposit is located close enough to existing transportation infrastructure to access rapidly growing, major markets in the glass and ceramics industries, both in the northeastern U.S. and Europe. There are only three competing lithium minerals producers in the world with the Bikita mine in Zimbabwe being the only major producer of petalite. The other lithium deposits produce spodumene, a less desirable lithium mineral. Lakefield Research Limited has successfully designed a process to produce an ultra-pure petalite concentrate containing up to 4.65 percent lithium oxide, and as little as 0.014 percent iron oxide, low levels of soda and potash, and negligible amounts of other trace elements. With these specifications, Avalon will have an excellent quality product for glass-ceramics applications such as Corningware®, CERAN® stove tops, and other thermal shock-resistant products. Lakefield is presently designing the balance of the flowsheet to produce separate concentrates of rubidium-rich K-feldspar, albite, mica, tantalum, tin, and high-purity quartz. Initial test work indicates that the feldspar products will be of exceptional quality. The K-feldspar concentrates contain 11-12 percent K20 and 1 percent Rb20, while the sodaspar contains over 10 percent Na20, and both have very low iron (0.01 percent Fe203). A preliminary economic model shows that with an initial production rate of 90,000 mt (100,000 st) per year, expanding to 170,000 mt (190,000 st) per year over 5 years, the project is capable of generating over CDN $10 million per year in pre-tax cash flow by year 5 on a capital cost of approximately CDN $30 million.

Jan 1, 2001

By J. F. T. Agapito, L. J. Gilbride, K. Hollberg

Room-and-pillar mining at the Big Island Mine uses narrow, yield (i.e., load transferring) pillars to achieve high resource recovery and productivity. Two flat-lying 3- to 3fi-meter (10- to 11fi-ft) seams are mined. The interburden between the seams is about 10 meters (33 ft) and the cover depth is 250 to 330 meters (820 to 1,080 ft).Most of the mining has been single-seam, but two-seam mining will begin in the near future. Yield pillars minimize stress transfer between the seams. However, it is important that good long-term stability be maintained to prevent subsidence over a large portion of the mine beneath the Green River channel. Three stress issues impacting stability are discussed in this paper: (1) higher-than-gravity vertical pre-mining stresses, (2) time-dependent stress transfer or arching, and (3) stresses induced by strata gas. Although the stress environment and behavior is not fully understood, steps have been taken in mine design and operations to minimize impacts to stability. Stress determinations have been very important to verify analytical predictions used in mine design and in long-term stability assessment.

Jan 1, 2004