摘要:

Coal is cleaned industrially by freeing the occluded mineral impurities and physically separating the coal and refuse particles on the basis of differences in density, settling characteristics, or surface properties. While physical methods are very effective and low in cost when applied to the separation of coarse particles, they are much less effective when applied to the separation of fine particles. Also they can not be used to remove impurities which are bound chemically to the coal. These deficiencies may be overcome in the future by chemical cleaning. Most of the chemical cleaning methods under development are designed primarily to remove sulfur from coal, but several methods also remove various trace elements and ash‐forming minerals. Generally these methods will remove most of the sulfur associated with inorganic minerals, but only a few of the methods seem to remove organically bound sulfur. A number of the methods employ oxidizing agents as air, oxygen, chlorine, nitrogen dioxide, or a ferric salt to oxidize the sulfur compounds to soluble sulfates which are then extracted with water. The sulfur in coal may also be solubilized by treatment with caustic. Also sulfur can be removed by reaction with hydrogen at high temperature. Furthermore, it is possible to transform the sulfur bearing minerals in coal to materials which are easily removed by magnetic separation.

ISSN:0094-243X    

DOI:10.1063/1.32949

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Subjecting slurries of a wide variety of coals and other carbonaceous fossil fuels to anodic oxidation in an aqueous electrolyte produces relatively clean gaseous carbon oxides, with clean hydrogen production at the cathode. Reaction stoichiometry some preliminary aspects of proposed mechanism and chemistry are discussed along with kinetic and thermodynamic considerations. Rate data interpretations are considered in reference to potential scale‐up to specific rates of industrial interest and importance. Reaction products (in addition to hydrogen), product compositions, possible process flow systems, and approximate process economics are also treated in preliminary fashion.

ISSN:0094-243X    

DOI:10.1063/1.32950

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The objective of this project is to improve the magnetic separation of coal and pyrite by enhancing the magnetic susceptibility of pyrite in run‐of‐mine (ROM) coal through the use of selective pretreatments such as dielectric heating and induction heating. Separation of pyrite from coal would be facilitated by changing a portion of each pyrite particle to a more magnetic form. The selective magnetic enhancement of pyrite in coal by dielectric heating was investigated fundamentally and experimentally. Fundamental treatment consisted by the measurement of the dielectric properties, at frequencies ranging from 1 HMz to 11.7 GHz, of a selection of coals and their pyritic fractions. These values were then used to calculate the theoretical heating that would be produced in these materials and their mixtures. The experimental treatment involved heating fractions and their mixtures at 27 and 2,450 MHz. Results showed limited agreement between theoretical and experimental heating and that it is possible to selectively heat pyrite in coal. Preliminary data indicate an increase in the apparent mass susceptibility of dielectically heated pyrite samples that is roughly proportional to the time and power of pretreatment. Magnetic separation tests are being started.

ISSN:0094-243X    

DOI:10.1063/1.32951

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The concluding panel session was devoted to the interaction of research with coal technology development. The four panel members discussed this from the viewpoints of their respective experience in the industrial, academic, and governmental sectors.

ISSN:0094-243X    

DOI:10.1063/1.32952

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We are currently applying density gradient centrifugation (DCG) techniques to the separation of the maceral constituents of coal. The DGC technique has several advantages over the often used sink‐float method. DGC permits rapid separation of 2‐3 g of coal into the component maceral groups and provides a visual means for observing the maceral content and densities of the maceral species. Prior to separating the macerals by DGC, the coal samples were ground to &angupr;3&mgr;m average particle size using a fluid energy mill and nitrogen carrier gas. Maceral separation was performed by layering a slurry of the coal on a 1.6 L density gradient of CsCl, whose high and low density (0.1‐1.5 g/cc) encompasses the densities of the macerals to be separated. After centrifuging, the density gradient was pumped into a fraction collector. The fractions were microscopically analyzed for maceral content. We have separated two bituminous coals containing substantial amounts of exinites and inertinites. Many of the fractions were over 90% pure with respect to a single maceral group. Examination of the separated fractions revealed that exinites and inertinites have broad ranges in density and in H/C ratios in a single coal; thus care should be taken to carefully define the density range of macerals in this group for any chemical or physical properties to be examined.

ISSN:0094-243X    

DOI:10.1063/1.32954

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Cretaceous bituminous coals of known rank R¯0max, vitrinite reflectance) have been examined by ESR (electron spin resonance) and ENDOR (electron nuclear double resonance) techniques. Both highly oxidised (outcrop) and unoxidised mine‐run Balmer coal from the Crowsnest field have been subjected to heat treatment (200‐900°C), and the matrix proton ENDOR signal studied as a function of applied microwave and rf power. Changes in ENDOR line shape and intensity are described with particular emphasis on the presoftening region of the unoxidised coal. A comparative study of the carbonization of hvb and 1vb coking coal from the Crowsnest is reported.

ISSN:0094-243X    

DOI:10.1063/1.32956

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Approximately one hundred framboids from coals, shales and lake bottom sediments have been individually examined by x‐ray diffraction (XRD) to determine their composition and their structure. Fresh, lake bottom framboids were largely composed of greigite accompanied with kaolinite. Aged, lake bottom framboids were mixtures of greigite and pyrite. Coal and shale framboids are predominately composed of iron pyrite either entirely or accompanied with other compounds. Occasionally, framboids were found entirely encased by quartz. Some framboids were composed of materials that could not be identified. The pattern of one such framboid was indexed with a tetragonal cell having the dimensions a = 4.1288 A˚ and c = 8.2400 A˚. The Laue XRD patterns indicated that the microcrystallites of framboids were randomly oriented; no preferential orientation was found. It is concluded from these patterns which exhibit spots plus a continuous halo that the cementing material is a fine grain version of the same material of which the framboid is composed.

ISSN:0094-243X    

DOI:10.1063/1.32958

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

PIXE provides simultaneous analysis of up to 80 elements with a single sample aliquot. An efficient hybrid statistical technique for interpreting the x‐ray spectra has been developed. The sensitivities vary smoothly with atomic numbers Z from .1 to 10 ng/cm2for elements above Z = 20. Comparison of PIXE to Atomic Absorption is made and good agreement is shown. Analysis results for powdered and digested coal samples are presented along with analysis of several USGS rock and sediment samples. PIXE is found to be a cost‐effective method of analysis, especially for studies which require simultaneous detection of many trace elements.

ISSN:0094-243X    

DOI:10.1063/1.32960

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A recently develped analytical method using the EPM (electron probe microanalyzer) measures organic sulfur directly and avoids the uncertainty of calculating organic sulfur content by difference. Analysis of 18 different coals (from 10 states, ranging in rank from subbituminous C to low vol. bituminous, and in age from Pennsylvania to Palaeocene) shows that organic sulfur contents of coals can be calculated from the organic sulfur contents of the vitrinite in the coals. This empirical relationship exists because vitrinite is the dominant maceral type is most coals and generally has a sulfur composition intermediate between exinites and inertinites. For EPM organic sulfur analysis, representative samples (−20 to −60 mesh) are potted in 1″diameter epoxy pellets, polished and carbon coated. Vitrinite grains are identified during analysis by shape and texture, with results equivalent to oil immersion, reflectance techniques. According to t‐statistics, analyzing 15 vitrinite grains achieves a maximum variability of less than 0.20 wt % from the ’’true’’ organic sulfur content of coals containing less than 2.00 wt % organic sulfur. Neither operator experience nor variation in coal composition and rank appear to bias results. A mojor problem with the EPM technique has been finding a suitable EPM sulfur standard. Recently, in cooperation with L. A. Harris, Oak Ridge National Laboratory, we have prepared a good standard, derived from a petroleum coke, which is stable under an electron beam and contains a uniform sulfur content.

ISSN:0094-243X    

DOI:10.1063/1.32914

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The Coal Research Bureau at West Virginia University is currently using a multiple analysis technique to examine minerals in coal. This technique is unique because it involves examining the minerals in a coal sample utilizing five independent methods: (1) X‐ray powder diffraction, (2) infrared spectroscopy, (3) scanning electron microscopy with energy dispersive X‐ray analysis, (4) optical petrography, and (5) normative mineral calculations based on elemental analyses. This technique of multiple analyses produced both more accurate identifications and quantifications than would have been possible with only one or two of the methods, and additionally important information on mineral compositions, associations, and sizes and shapes. Application of this multiple analysis technique to the Pittsburgh coal of northern West Virginia revealed the presence of the minerals illite, kaolinite, quartz, feldspars, muscovite, calcite, dolomite, apatite, bassanite, gypsum, pyrite, marcasite, hematite, and rutile. X‐ray powder diffraction, infrared spectroscopy, and normative calculations were used to quantify most of these minerals, while optical petrography and scanning electron microscopy were used to identify minor minerals and to determine mineral associations and morphologies.

ISSN:0094-243X    

DOI:10.1063/1.32913

出版商:AIP    

年代:1981

数据来源: AIP