Lignite measuring

Lindqvist, J.K. (1990) Deposition and diagenesis of Landslip Hill silcrete, Gore Lignite Measures (Miocene), New Zealand. New Zealand Journal of Geology and Geophysics 33, 137-150. 

Typically, 40—50% of the carbon atoms ia lignite are ia aromatic stmctures while 60—70% of the carbon atoms ia Illinois bituminous coal are ia aromatic stmctures (7,8). By all of these measures, waste fuels are significantly more reactive than coal, peat, and other combustible soHds. 

A variety of measures must be taken to assure safe and continued operation. Because the natural water table is higher than the coal seams, or the seams are natural aquifers, it is necessary to pump water out of the pit or to drill weUs around the mine and pump to reduce the water table. The Rheinische Braunkohlenwerke (Rheinbraun) pumps water at a rate of 1-1.2 x 10 m /yr. Part of this water is processed to provide drinking water for Neuss and Dusseldorf. The tendency of lignite to ignite spontaneously requires care in the amount of face that is exposed, especially in naturally dry, hot, windy climates. 

Long), are shown in Figure A. Construction lines like OAB suggest that the coals were around subbituminous rank before intrusion in the complete sequence of seams in the coal measures there might have been a range of rank from high rank lignitous to subbituminous, or subbituminous to very low rank bituminous. 

The total moisture in coal is the determination of the moisture (in all forms except water of crystallization of the mineral matter) that resides within the coal matrix. In fact, moisture (or water) is the most elusive constituent of coal to be measured in the laboratory. The moisture in coal ranges from 2 to 15% by weight in bituminous coal to nearly 45% by weight in lignite. 

The refractive index of coal can be determined by comparing the reflectance in air with that in cedar oil. A standard test method (ASTM D-2798) covers the microscopic determination of both the mean maximum reflectance and the mean random reflectance measured in oil of polished surfaces of vitrinite and other macerals in coal ranging in rank from lignite to anthracite. This test method can be used to determine the reflectance of other macerals. For vitrinite (various coals), the refractive index usually falls within the range 1.68 (58% carbon coal) to 2.02 (96% carbon coal). 

The aromaticity for several samples of Northern Great Plains lignites, as measured on run-of-mine material, lies in the range of 0.61 to 0.66. A sample of Australian brown coal had an aromaticity of 0.56 a sample of Minnesota peat had an aromaticity of 0.50. Samples of vitrinite concentrates from the Northern Great Plains lignites were more aromatic, with measured values from 0.72 to 0.74. 

Figure 4, The scattered intensity for Beulah lignite as measured with the Bonse-Hart and Beeman collimation systems (squares) at the University of North Dakota. The curve was drawn from a least-squares fit of Equation 6, and the points are the corrected scattered intensities.

A different type of analysis has now provided this information (20) The dimension distributions p(a) of independent spherical scatterers with uniform density and diameter a which produces each of the terms in the sum in Equation (3) can be calculated (19) After obtaining the constants in the sum in Equation (3) by least-squares fits of this equation to the scattering curve measured for Beulah lignite at the University of North Dakota, we used these constants to evaluate the sum of the pore-dimension distribution functions for uniform spheres that are obtained (19) from the terms in the sum in Equation (3) The sum of these pore-dimension distributions was very similar to the power-law distribution given by Equation (4) The fact that we could obtain almost the same power-law dimension distribution by two independent methods suggests that such a distribution may be a good approximation to the pore-... 

By modifying and extending the results presented in Reference (19), we have developed a technique to calculate pore-dimension distributions from the scattering curves for lignites. Equation (5) was obtained under the assumption that the dimension distribution was given by Equation (4) for all values of the dimension a Calculations (20) show that if, on the other hand, the scattered intensity can be approximated by Equation (5) for < h < ho, and if the entire measured curve can be represented by the expression... 

The expoaents 7-y in Table 3 fall into two groups, with values less and greater than 3. The difference in exponents is compensated for by a change in the value of the constant D2, so that the resulting fitted curves are nearly the same for all of the lignite samples, just as the measured scattering curves are almost... 

The proton NMR spectrum of the Me2S0 extract of the lignite was obtained using a XL-200 Fourier transform proton NMR spectrometer. Details of lignite extraction with Me2S0 are described elsewhere (, 5). Instrumental conditions for the measurement of the spectrum were as follows frequency - 200 MHz proton sample state - liquid solution solvent - Me2S0-dg locked sample concentration - ca. 200 mg/10 ml probe temperature - 25 C sweep width - 2600.1 Hz acquisition time - 1 second internal reference - tetramethyl silane number of transients - 1500 pulse width - 5.0 piseconds. 

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