Abstract: A method for reducing the sulfur content in combustion gases from burning coal includes the steps of applying opposite electrostic charges to fuel particles and to reaction particles, and mixing the oppositely charged particles prior to combustion to facilitate the formation of sulfur compounds from sulfur in the fuel upon combustion of the fuel, to thereby reduce the sulfur content in the combustion gases. The reaction particles are preferably a carbonate such as CaCO.sub.3 and MgCO.sub.3. The apparatus for implementing the method includes a first pneumatic line for conveying fuel particles, and a first electrostatic charging device for applying an electrostatic charge to the fuel particles conveyed in the line; and a second pneumatic line for conveying carbonate particles, and a second electrostatic charging device for applying an electrostatic charge to the carbonate particles conveyed in the line that is opposite in polarity to the charge applied to the fuel particles.

Abstract: A mine ventilation structure for installation at the intersection of first and second passageways in a mine. The ventilation structure defines a first passage communicating with the first passageway and a second passage communicating with the second passageway. The ventilation structure includes a pair of generally parallel, spaced-apart side walls defining the side walls of the first passage, and a plurality of elongate deck panels extending between the side walls and forming the roof of one of the first and second passages and the floor of the other of the first and second passages. Each deck panel is a sheet metal panel generally of inverted channel shape in transverse cross section, having an upper web and side flanges extending down from the upper web at opposite sides of the web. Tie bars hold the deck panels together in fixed side-by-side relation with the side flanges of the panels closely adjacent one another so that the webs of the panels form a substantially continuous surface.

Abstract: A structure including at least two generally parallel, spaced-apart side walls, and a plurality of roof panels extending between the side walls for forming the roof of the structure. Each roof panel has opposite ends overlying the upper ends of respective side walls. The roof panels and side wails are constructed with a bayonet connection device for quick connection.

Abstract: A power mine door system including a door frame to be installed in a mine passageway to define a generally rectangular doorway. A mine door is defined by a pair of generally rectangular door leafs which are hinged on the door frame at opposite sides of the doorway for swinging between an open position to permit passage through the doorway and a closed position in which the door leafs are generally coplanar and close the doorway. The door leafs are so dimensioned that there is a substantial vertical gap between the door leafs when they are closed to accommodate convergence of side walls of the passageway. A relatively wide vertical sealing flap is secured to one of the door leafs for overlapping a face of the other door leaf when the door is closed for covering the gap between the door leafs.

Abstract: A mine door system including a door frame to be installed in a mine passageway to define a generally rectangular doorway. A mine door is defined by a pair of generally rectangular door leafs which are hinged on the door frame at opposite sides of the doorway for swinging between an open position to permit passage through the doorway and a closed position in which the door leafs are generally coplanar and close the doorway. The door leafs are so dimensioned that there is a substantial vertical gap between the door leafs when they are closed to accommodate convergence of side walls of the passageway. A relatively wide vertical sealing flap is secured to one of the door leafs for overlapping a face of the other door leaf when the door is closed for covering the gap between the door leafs.

Abstract: A door system for use in a mine stopping comprises a door frame for installation in the stopping to define a doorway, a door hinged to a first side of the door frame for swinging between an open position and a closed position in which the door closes the doorway, and a latch for latching the door in its closed position. The latch comprises a strike which is secured to a second side of the door frame generally opposite the first side and which has a strike plate portion disposed in the doorway in a plane generally perpendicular to the plane of the doorway and spaced from the second side of the door frame thereby to create a void between the strike plate portion and the second side of the doorway. The strike plate portion has a latching aperture therein.

Abstract: A contractible mine stopping adapted to be installed to extend as a vertical wall from the floor to the roof of a passageway in a mine, comprising a series of rows of substantially solid substantially non-compressible blocks of substantially fire-resistant material stacked one on top of another, and at least one row of contractible substantially fire-resistant block-like members adapted to contract without loss of structural integrity when the wall is subjected to a compressive load, as during a convergence of the floor and roof of the passageway. Each block-like member is preferably a hollow metal member which, when subjected to a compressive load, is adapted to contract heightwise of the member a distance corresponding to at least a major portion of the height of the member without loss of structural integrity of the member.

Abstract: A mine door system adapted for installation and a passageway in a mine, comprising a door frame adapted to be installed in the passageway and defining a doorway spaced below a ceiling of the passageway and mine doors hingedly mounted on the door frame for movement between open and closed positions. The system further comprises a top panel structure for substantially closing the space between the door frame and the ceiling of the passageway, the top panel structure being readily contractible heightwise of the passageway without loss of its structural integrity to accommodate a convergence of the ceiling and floor of the passageway without any substantial heightwise deformation of the door frame.

Abstract: A contractible mine stopping adapted to be installed to extend as a vertical wall from the floor to the roof of a passageway in a mine, comprising a series of rows of substantially solid substantially non-compressible blocks of substantially fire-resistant material stacked one on top of another, and at least one row of contractible substantially fire-resistant block-like members adapted to contract without loss of structural integrity when the wall is subjected to a compressive load, as during a convergence of the floor and roof on the passageway. Each block-like member is preferably a hollow metal member which, when subjected to a compressive load, is adapted to contract heightwise of the member a distance corresponding to at least a major portion of the height of the member without loss of structural integrity of the member.