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By Thomas J. Feeley

The US Department of Energy (DOE) is supporting the engineering development of three advanced physical coal cleaning technologies: selective agglomeration, advanced flotation and advanced cycloning. Each is capable of significantly reducing the pyritic-sulfur content of US coals. The objective is to provide the coal and electric-utility industries with a cost-effective option for addressing the SO, emission reductions required by the 1990 Clean Air Act Amendments (CAA). A secondary objective is to evaluate the potential of advanced coal cleaning for removing trace elements that are precursors to the formation of hazardous air pollutants (HAS). The proposed National Energy Strategy (NEE) and the 1990 CAA lay a foundation for a more efficient and environmentally sustainable energy future (1991). The need to use energy resources in an environmentally sound manner presents critical challenges and opportunities for coal preparation during the next decade, particularly regarding the control of SOS and HAY emissions. The principal challenge is the development of cost-effective coal preparation approaches for sulfur and HAY precursor removal.

Jan 1, 1993

By O. Ofor

Finely-ground hematitic ore, too high in silica (quartz) to be commercially viable, was treated by emulsion flotation. A three-component emulsion mixture was used at temperatures ranging from ambient (22° C) to 30° C, 40° C, 49 °C, 59° C and 68° C. The optimal emulsion dosage and composition at ambient temperature were used to determine that dosage for higher-temperature flotation tests. The crushed ore (100%, -8 mesh) was repeatedly washed with tap water, and the filtrate's ionic content was analyzed. The separation efficiency values (a measure of the selective separation and concentration of hematite from gangue minerals) demonstrated temperature dependence, with marked increases at temperatures above ambient. The optimal separation efficiency occurred within the range from 30° C to 60° C. The improved separation efficiencies at temperatures exceeding ambient are explained by quartz depression. This depression is attributed to: • the precipitation of quartz-activating cations, principally calcium and magnesium, at increasing temperature; and • temperature's effect on the collector's solubility and attachment to the aqueous hematite surface.

Jan 1, 1993

By Sigmund J. Sulinski

The following is a progress report on a continuing study being made by the Sanitary District for purposes of developing reliable data for predicting costs and progress on future tunnel contracts. All data available to date on five separate tunnel contracts has been analyzed. All were machine-mined in soft ground, all used steel ribs and wood lagging and finished inside diameters varying from 5'6" to 6'6". Basic data regarding progress per shift, hours mined per shift, hours of downtime per shift, cause of downtime and type of soil mined were reported by the District's resident engineer at the job site. Figure 1, Weekly Mining Report is an example of the form used. Data regarding manpower and equipment used during tunnelling operations was also supplied by the resident engineer during the course of construction. Soil type being mined was verified by the resident engineer during construction, by visual observation, and compared with data listed on a previously prepared soil profile. The soil profile is a graphic presentation of anticipated soil stratas superimposed on a cross section

Jan 1, 1997

By B. Whitmoyer, J. Tian, J. E. Sneckenberger, M. A. Jerabek, C. A. Chandler

A computational procedure has been developed to determine the lung volume function for the upper airways of the human respiratory system. This analytical procedure computes a person's partial lung volume from an experimental two-microphone acoustic measurement of the upper airway passages obtained through a molded tubular mouthpiece. The theoretical transfer function for the two microphone signals as well as the related acoustic impedance and reflection coefficient for the upper airways are calculated using two-channel spectrum analysis techniques. An inverse spectrum analysis scheme then converts the reflection coefficient to an impulse response from which the airway area function is extracted using an area recovery algorithm. Numerical integration of the upper airway area function yields the lung volume function for the upper airways of the human respiratory sysytem. A software program to accomplish this computation of human upper airway volumes will be described in this paper. Application of this computational procedure to the measured tracheal acoustic impedances of 15 human subjects will illustrate the program's capability toward early detection of lung dysfunction using a prototype clinical facility.

Jan 1, 1991

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of. This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium sulfite and calcium sulfate. The majority of the sludge is simply landfilled, but with increasing landfillimg costs this can cost the plant millions of dollars per year. As a result, this option is rapidly becoming less attractive. Producing marketable materials from the sludge is a far more promising avenue, provided that the products can meet the necessary specifications at a reasonable cost. In this paper, a method is described for using froth flotation and water-only cyclones to remove unreacted limestone from scrubber sludge. The water-only cyclone was found to be very effective for removing the coarser unreacted limestone, grinding ball chips, gravel, and similar coarse impurities. Froth flotation was found to remove fine unreacted limestone, with a minimum of reagent addition.

Jan 1, 1995

By A. Unal

Coal resource characterization usually calls for estimating more than one variable over a block or node simultaneously. Within the realm of geostatistics, each variable has been evaluated independently from the others assuming a lack of significant correlation. Research conducted with coal seams, however, has shown that the variables of immediate interest, such as seam thickness, ash, sulfur content, and density depict some correlation schemes in distinct zones, if not throughout the entire area. The above findings have two immediate consequences : (1) correlation analyses provide guidelines to determine the geologically distinct zones, and (2) where possible, cokriging should be used instead of kriging. This will maximize data utilization decreasing the frequently criticized high estimation errors. The cokriging formulation will also provide more accurate estimates for under sampled variables using better-sampled ones. This is a common case with coal with regard to the non-cored reconnaissance drill holes for which only very few variables were recorded. A case study illustrates the improvements that may be obtained by taking advantage of the intervariable correlations.

Jan 1, 1986

By J. Hong, K. Han, C. Park, C. Yoon, H. Yoon, N. Kim

The contents of three platinum group metals (PGM-platinum, palladium and rhodium), from the spent automotive catalyst, and two NIST SRM (National Institute of Standard and Technology Standard Reference Material, Used Auto Catalysts) were determined by the X-ray fluorescence (XRF) spectrometry. The XRF technique has been proven to be a fast, effective and accurate method in determining not only PGM but also other solid materials of less soluble for wet digestion analysis. The detection limit of the XRF analysis is better than that of the inductively coupled plasma mass spectrometry which usually requires significant dilution to avoid high dissolved solid concentration. However, the XRF technique suffers from a strong matrix dependent problem. The objective of this study was to examine the applicability of the XRF analysis where the sample matrix was not exactly the same as the standard materials with particular reference to PGM analysis. This study enabled to compare the effect of various matrices including alumina, iron, copper and nickel on determination of the contents of PGM.

Jan 1, 2004

By Xiangze Shu, Yuzhong Xing

All programs used to optimize main fan nowdays have to be run on the large and medium- sized computers. With a lot of array elements, complex processes, low convergence speed and large storage, these programs are both time consuming and difficult to be used in the micro computer. This program uses two languages (dBASEIII and BASICA) to calculate the network and to choose the fan respectively. It allows user to compare and choose the parameters of various kinds of fan and to transfer the selected fan parameters to the master program by a data communication system. Then the user can get the air quantity, the air pressure, the power and the efficiency of the main fan. The advantages of this program arc as follows: 1. It can be run on IBM-PC or compatible micro computer. 2. It can select a fan more quickly and less time consumingly. 3. It can choose desired one or a set of fans according to user's requirements. 4. It is suitable for the research institutions and coal mines.

Jan 1, 1991

By C. Flores, L. G. Twidwell, T. S. Jordan

It is well known that manguniferous silver ores containing manganese intimate) associated with silver are not amenable to conventional extraction methods. The segregation process has been applied primarily to the recovery of copper from oxidized and oxide-sulfide ores. A new alternative process, consisting of segregation roasting followed by flotation to recover the silver from refractory manganiferous silver ores, was studied using a 23-factorial experimental design. Laboratory investigations were conducted on a manganiferous silver ore analyzing 0.02% copper, 0.09% lead, 0.33% zinc, 12.55% manganese and 187 g/t silver. The investigation was designed to study the effects of the addition of salts, coke and copper (11) oxide on silver recovery. The results indicated that 79.3% of the silver can be recovered in the absence of copper oxide and 88.4% of the silver can be recovered with a copper oxide content of 1.5% at 750°C, 2% salt (NaCI). 1 % coke and 30 min of roasting. It was concluded that the addition of copper oxide improves silver recovery.

Jan 1, 1996

By Fred H. Seymour

In spite of the progress made by geostatistical theory over the years, evaluation of low grade open pit gold deposits continues to be challenging. Many Carlin type deposits are modelled from exploration drilling spaced on 10C foot centers. From these drill holes, 50 by 50 by 20 foot blocks containing about 4000 tons of material are estimated. The block size is a compromise between being large enough for a good geostatistical estimation and being small enough for practical pit limit analysis and mine planning. Most of these gold deposits are highly variable and include ore and waste zones that are too small to be properly defined from exploration drilling information. Because of this, selective mining is controlled by sampling closely spaced blast holes where the density can be as high as 50 blast holes per exploration drill hole intercept. Figure 1 illustrates an example of the ore/waste contact definition before and after blast hole sampling. With exploration information only, a tentative ore/waste contact can be drawn between the exploration blocks.

Jan 1, 1989

By B. J. Arnold

A coal's size distribution clay content and moisture content can affect its handling behavior. But the combined effects of these properties and the effects of other properties are not known. Research underway at CQ Inc.'s (formerly EPRI's) Coal Quality Development Center (CQDC) and at Iowa State University (ISU) will answer these questions as part of a four year project to develop a coal handleability index for utilities to use when specifying coals. This paper will present preliminary data from the first year of the project, which focused on obtaining data on the chemical and physical properties of carious coals and their measured handling properties. Additionally, size, ash and moisture analyses and shear test data for several coals used at one power plant will be presented along with correlations between these physical and chemical properties and the measured handling properties. These data lead to the conclusion that while moisture content is the most important variable, the amount of -44 µm (-325 mesh) coal fines is a significant factor in determining coal handling behavior.

Jan 1, 1992

By M. H. H. Mahmoud, T. A. El-Barbary, E. A. Abdel Aal, I. A. Ibrahim, A. K. Ismail

Fertilizer-grade phosphoric acid with a P2O5 concentration of 50% should contain less than 1.5% Fe2O3, otherwise, the P2O5 water solubility of the fertilizers prepared from high-iron acids will be low. High-iron Egyptian phosphate concentrates fromAbu-Tartur and Sebaiya- West were leached with sulfuric acid and recycled phosphoric acid to produce 50%-P2O5 phosphoric acids containing 4.0% and 2.7% Fe2O3, respectively. The high iron contents were reduced to the industrially accepted limit of 1.5% Fe2O3 by precipitation with potassium sulfate. The factors affecting the effi¬ciency of the precipitation process, e.g., temperature, time and K2O/Fe2O3 ratio, were systematically studied, and the optimum conditions were achieved. The clarification of the prepared phosphoric acid from iron-containing sludges was also investigated by varying the time and temperature. The utilization of the separated sludges as fertilizer and recovery of P205 by pulping in water were also evaluated.

Jan 1, 2000

By A. M. Marabini, V. Alesse, Belardi. G.

An alternative flowsheet was designed for the flotation treatment of a complex sulfide ore from the Sotiel Mine in Spain. The ore contains 0.71% Cu, 2.24% Pb and 5.63% Zn. Two specially developed synthetic collectors, methyl-mercapto-benzoxazole (MMBO) and 6n-propoxy-mercapto-benzo-thiazole (PMBT), were examined. MMBO exerts a specific action on copper and zinc minerals after treatment with copper sulfate, and PMBT exerts a specific action on Pb minerals. Flotation operating variables (pH, frother type, frother quantity and feed particle size) were examined by means of rougher flotation tests to determine the optimum conditions for the new collectors. Once the optimum conditions were determined, a series of open flotation circuits were run on feeds of various particle sizes (obtained by different types of grinding). The objective was to obtain high-grade Cu and Zn concentrates. The results of the open-circuit tests demonstrated that a Cu concentrate grading from 18% to 23% Cu and a Zn concentrate grading from 40% to 48% Zn can be produced.

Jan 1, 1996

By S. Majumder

The longwall face supports are provided to prevent the caving of the immediate roof at the working face. The thickmess of the immediate roof may be obtained from the working height and the average bulking factor. A strong bed, capable of withstanding maximum bending moment among the beds within the above roof, can be identified. The load on the strong bed may be obtained by finding out the overlying beds that will rest on the former during sagging. The limiting span, L, for this unsupported loaded bed, as a beam with built-in ends, can be calculated. The support density required at the supported span (face to goaf edge), a, during the first fall, is now estimated with a view to have a safety factor 2 at the face end, when bending failure occurs at the barrier end. However, the above value is inadequate to provide necessary safety margin against bending failure at the face end, during the subsequent cavings as cantilever, for L/a less than 20.6. d For the latter case a separate expression is derived.

Jan 1, 1986

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By D. Harris, M. Osterberg

This paper examines the economics of acquiring mineral exploration rights by royalty-rate bidding when the royalty basis does not provide for full cost recovery. Bidding takes place prior to exploration and the documentation of actual tonnage and grade. Consequently, it increases considerably the risk to exploration capital when the fraction of cost recovered is small and the product price exhibits large fluctuations. Price and grade risk are demonstrated on a 360-Mt (400-million-st) porphyry copper deposit by Monte Carlo simulation of discounted-cash-flow analysis. Copper price is modeled as a stochastic price process, and costs are based on US Bureau of Mines cost models. When both grade and price risk are considered, the probability for a negative NPV is 0.54, given a royalty rate of 5% applied to a basis that allows the recovery of costs up to 50% of product price. Investment risk could be considerably reduced by defining the royalty basis to allow greater cost recovery. Although such a basis would require society to share in the risk, society would benefit from greater resource development.

Jan 1, 2000

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice (USPAP) and the Australian VALMIN Code to a complex mineral property appraisal assignment and previously to some modest assignments. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others and information and statements required from the client under the VALMIN Code. The exercises highlighted many positive features of both sets of standards. However, the author concluded that, without modification, VALMIN is incompatible with USPAP and the US regulatory environ¬ment. The author found that VALMIN violates US legal decisions regarding real property appraisal due to its requirement to include many items of business value. The US Securities and Exchange Commission's prohibition on reporting quantitative resource estimates proved to be a severe problem under VALMIN. Some VALMIN requirements could not be met due to the extent and quality of documents specified. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed. Management considerations for complex mineral-property appraisal assignments are also presented.

Jan 1, 2000

By Anthony G. Fonseca, W. W. Wen

About 45-50% of the coal mined in the U.S. passes through coal preparation plants; east of the Mississippi River this number increases to about 75-80%. 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, as commercially practiced today, is an effective process achieving 75-803 ash reduction, 15-8m trace element reduction, and 85-90% Btu recovery; it is less effective for pyrite reduction (35-70%), and on-line operating time (40-60%), and suffers from obsolete control systems. Methods will be discussed for reducing costs of coal preparation and improving the performance of coal preparation plants. Comments are included on equipment selection, especially for -28 mesh coal, and prep plant operation and control practices. Btu recovery, ash and pyrite reduction, fines processing including dewatering and slurry fuel use options are emphasized. Trace element removal and expert control systems for maximization of prep plant operation also will be highlighted.

Jan 1, 1995

By J. V. Calara, J. D. Miller

The sign of the surface potential for complex non-reactive ionic solids cannot be predicted solely from consideration of the hydration energy of gaseous ions which constitute the ionic lattice. Accurate analysis of these systems must involve the hydration energy of surface ions, which requires knowledge of the crystal structure, the identification of cleavage planes, and the calculation of binding energies of surface ions. Surface binding energies for ionic solids can be deter- mined if the Surface Madelung Constant is known. A computational technique was developed for the calculation of Madelung Constants for infinite lattices which gives excellent agreement with the values calculated by other more complicated methods reported in the literature. Extension of this technique permits the calculation of Surface Madelung Constants and binding energies of surface ions, ?Us, for semi-infinite solids. The hydration free energy of gaseous Ions, ?Fh, together with the calculated binding energy of surface ions, ?Us, allows calculation of the hydration energy of surface ions, ?Gh, as for the case of the ionic solid, MX:

Jan 1, 1976

By Josef Arnold, Norbert Fuegenschuh

The “Eggequerung” is an important part of the German Railway’s (Deutsche BahnAG) modernized Dortmund—Kassel line. The heart of this 13-km-long (8 miles)construction lot is the double-track Egge Tunnel with a total length of 2,880 m(9,450 ft.). The tunnel was driven using the New Austrian Tunnelling Method (NATM).The construction contract also called for a reinforced concrete secondary lining, guaranteed for a full water pressure of 30 m (100 ft.) water column. Preliminary geological study already showed that very problematic geological-hydrological conditions would have to be expected. This talk describes the chosen NATM driving concept that was adapted to the prevailing geological and hydrological conditions, the special driving method applied in geologically difficult zones as well as the water control concept used during driving. The flexibility and the limits of the NATM under exceptional hydrological conditions are illustrated. Also described are reinforced concrete lining works for the watertight secondary vault (reinforced concrete secondary lining without water-proofing membrane).

Jan 1, 2003