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A B S T R A C TFly ash was collected from individual mechanical and electrostatic precipitator (ESP) hoppers at a 130-MW pulverized-coal utility unit burning a southeastern Kentucky moderate-to high-S Pennsylvanian Fire Clay coal. The fly ash particle size is generally similar within each row of the mechanical and ESP hoppers, with the mean particle diameter decreasing from >36 μm in the mechanical hoppers to 6 μm in the last ESP row. Rare earth element (REE)-bearing phases occur within fine minerals and, possibly, as part of the fly ash glass phase. Transmission electron microscopy was used to identify Y-Ce-Nd-La-bearing regions within a glassy matrix. Y-and U-bearing zircons were also found in the fly ash. Total REE plus yttrium (REY) occupies a narrow range from 719 to 775 ppm, showing an overall lack of partitioning of the REY elements with respect to particle size and temperature in ash collection systems. The heavy REE increase and the light REE/heavy REE ratio decreases from the mechanical hoppers through ESP rows.

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The acid dissociation constants of 2,4,6-trimercaptotriazine (H(3)TMT, 1) were determined and now can be employed in the preparation of complexes having specific M-TMT (M = divalent metal; TMT = 2,4,6-trimercapto-1,3,5-triazinide, C(3)N(3)S(3)(3-)) ratios. For example, the combination of H(3)TMT (1) with Mg(OH)(2) at pH 7.1 leads to the crystallization of Mg(H(2)TMT)(2).6H(2)O (4). With the appropriate pH adjustment, the contiguous series of compounds Ba(3)(TMT)(2).8H(2)O (3), Ba(H(2)TMT)(2).7H(2)O (5), and BaHTMT.3H(2)O (6) can be isolated. The compounds were characterized by mp, IR, TGA, elemental analysis, and, in the cases of 4, 5, and 6, crystallography. The comparison of 4 with 5 and 6 offers an interesting view of the difference in hard and soft bonding with TMT. In the saltlike Mg structure of 4, there is extensive hydrogen bonding, but in the Ba structures, 5 and 6, covalent Ba-S bonding dominates.

The 2,4,6-trimercaptotriazine (TMT) ligand system is currently being used as a complexing agent for divalent metals although little is known about its chemistry. This report entails a description of the syntheses and structures of TMT complexes having the formula M(TMTH2)2·nH2O (M = Ca (1), Sr (2), and Ba (3), where n = 11, 11, and 4.5, respectively). In 1 and 2, the structures consist of alternating layers of hydrated metal cations and π-stacked TMT groups. A wide range of hydrogen-bonding interactions connect these layers. Compound 3 forms as a polymeric molecule with covalent bonds between the Ba atoms and TMT ligands. Each of the compounds was structurally characterized. X-ray data:  1, C24H104Ca4N24O44S24, triclinic, P1̄, a = 12.9622(7) Å, b = 15.9874(9) Å, c = 24.516(1) Å, α = 81.191(1)°, β = 89.560(1)°, γ = 72.433(1)°, Z = 2; 2, C6H26N6O11S6Sr, triclinic P1̄, a = 8.7454(5) Å, b = 11.7545(6) Å, c = 13.7292(7) Å, α = 66.529(1)°, β = 73.201(1)°, γ = 77.034(1)°, Z = 2; 3, C12H18Ba2N12O9S12, monoclinic, P21/c, a = 8.5576(4) Å, b = 21.028(1) Å, c = 20.276(1) Å, β = 96.440(1)°, Z = 2.

Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan, Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse (carbon dioxide (CO(2)) only) and vent (CO(2), carbon monoxide (CO), methane, hydrogen sulfide (H(2)S), and elemental mercury) emission estimates were made for each of the fires. Additionally, gas samples were collected for volatile organic compound (VOC) analysis and showed a large range in variation between vents. The fires produce locally dangerous levels of CO, CO(2), H(2)S, and benzene, among other gases. At one fire in an abandoned coal mine, trends in gas and tar composition followed a change in topography. Total CO(2) fluxes for the fires from airborne, ground-based, and rate of fire advancement estimates ranged from 0.9 to 780mg/s/m(2) and are comparable to other coal fires worldwide. Samples of tar and coal-fire minerals collected from the mouth of vents provided insight into the behavior and formation of the coal fires.