Overcast System for Mine Ventilation

Abstract

An overcast system to block an intersection between two or more mine passageways so as to prevent the mixture of intake air with return air. The overcast system includes a first sidewall formed of one or more prefabricated panels, a second sidewall formed of one or more prefabricated panels, and a top member formed of one or more prefabricated panels, such that the top side spans the width between the first sidewall and the second sidewall. A fire-resistant coating is applied to at least a portion of the first sidewall, the second sidewall, or the top member to provide an air-tight, fire-resistant structure. Each of the one or more prefabricated panels is formed from a composite material having one or more structural studs embedded at least partially therein.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to an overcast system used in mine ventilation that prevents the mixture of ventilation air at an intersection of two passageways within a mine. More specifically, the present disclosure relates to an overcast structure formed of a plurality of prefabricated panels and coated with spray-on material to create a substantially air-tight and fire-resistant structure.

Description of Related Art

In underground mining operations, there is a need to provide a ventilation system such that clean intake air may be introduced into the mine through a first passageway (or passageways), while contaminated return air may be removed via a separate, second passageway (or passageways). As the return air may contain methane, dust, or other contaminants, it is important that the intersection between these intake and return air passageways be blocked through the use of an air-tight partition and/or ducted via an overcast or undercast structure so as to prevent mixture of the ventilation air between the two passageways.

Previously, structures constructed of concrete block or steel plates were used to define the respective passageways. These structures were typically sprayed with sealants in an effort to form an air-tight passageway. However, these structures require large amounts of material and many hours of labor to construct. Furthermore, due to the numerous joints between adjacent concrete blocks and/or steel plates, air leaks were common, leading to both contamination of the respective passageways and loss of pressure throughout the ventilation system.

Efforts have been made to both simplify the installation process of partition structures and provide for better air sealing between passageways. For example, U.S. Pat. No. 5,879,231 discloses an overcast structure formed, in part, from a plurality of prefabricated panels affixed together. Each panel comprises an insulated core (e.g., polystyrene) having a plurality of strut wires passing therethrough, with the strut wires being connected to respective wire grids on either side of the insulated core. Rebar is then connected to the wire grids, and a layer of concrete (e.g., gunite or shotcrete) is applied over the wire grids and rebar so as to provide both structural integrity and an air-tight seal to the overcast.

While U.S. Pat. No. 5,879,231 may have provided for an overcast structure having a shortened installation process and sealing improvements over the previous concrete block and/or steel plate partitions, the need to provide and assemble the insulated cores, wire grids, rebar, and concrete coating during installation still resulted in a complicated and time-consuming process. Accordingly, an effective overcast system requiring fewer materials and simplified installation is desired.

SUMMARY OF THE INVENTION

It is an object of the present disclosure to provide an overcast system and method that overcomes some or all of the above-described deficiencies of the prior art.

One non-limiting embodiment of the disclosure includes an overcast system having a first sidewall formed of one or more prefabricated panels, a second sidewall formed of one or more prefabricated panels, and a top member formed of one or more prefabricated panels. The top member may span the width between the first sidewall and the second sidewall. A fire-resistant coating is applied to at least a portion of the first sidewall, the second sidewall, or the top member to provide an air-tight, fire-resistant structure. Additionally, each of the one or more prefabricated panels is formed from a composite material having one or more structural studs embedded at least partially therein.

To facilitate securement of the one or more prefabricated panels to an adjacent panel, the one or more prefabricated panels may include a tongue at one end thereof and define a groove at the other end thereof for receiving a tongue of an adjacent panel. A brace may be secured to the first sidewall and the top member to add further structural integrity to the overcast system.

The composite material may be an expanded polystyrene (EPS). Each of the one or more prefabricated panels may include two or more structural studs embedded at least partially therein. The structural studs may be S-shaped steel studs.

In one embodiment, a wire mesh is applied to at least a portion of a surface of the first sidewall, the second sidewall, and the top member. The fire-resistant coating may be a fiber-reinforced composite rock coating.

One or more wing walls may be attached to the top side of the overcast system, which may include at least one of a staircase, a ramp, and a ladder for traversing the overcast system.

Another non-limiting embodiment of the disclosure includes a method of forming an overcast system for mine ventilation, the method includes forming a first sidewall using one or more prefabricated panels, forming a second sidewall using one or more prefabricated panels, the second sidewall spaced apart from the first sidewall and forming a top member using one or more prefabricated panels. The top member spans the distance between the first sidewall and the second sidewall. The method further includes applying a flame-resistant coating to at least a portion of the first sidewall, the second sidewall, and the top member. Each of the one or more prefabricated panels is formed from a composite material having one or more structural studs embedded at least partially therein. The method may additionally include securing the first and the second sidewalls to a bracket and attaching the bracket to a mine floor.

These and other features and characteristics of the present disclosure, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and appended claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the disclosure. As used in the specification and claims, the singular form of “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a perspective view of an overcast system installed within an underground mine crosscut;

FIG. 2 is a perspective view of a prefabricated panel;

FIG. 3 is a partial top view of the prefabricated panel of FIG. 2;

FIG. 4 is a perspective view of an overcast system formed of prefabricated panels;

FIG. 5 is a partial cross-sectional view of the overcast system of FIG. 4 taken along line 5-5 as installed in a mine entry;

FIG. 6 is a side view of an overcast system having connecting cross-bars between prefabricated panels and a wire mesh thereon;

FIG. 7 is a partial perspective view of an overcast system having a ribbed expanded metal form thereon;

FIG. 8 is a side view of the application of a spray-on coating on an overcast system; and

FIG. 9 is a perspective view of the spray-on coating of FIG. 8.

DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary aspects of the disclosure. Hence, specific dimensions and other physical characteristics related to the aspects disclosed herein are not to be considered as limiting.

Referring to FIG. 1, an overcast system 100 in accordance with an aspect of the present disclosure is shown schematically in a crosscut of an underground mine. Overcast system 100 comprises a first sidewall 102, a second sidewall 104, and a top member 106. As will be set forth in more detail hereinbelow, the first sidewall 102, the second sidewall 104, and the top member 106 may each be formed of a plurality of interconnectable prefabricated panels. The first and second sidewall 102, 104 and top member 106 are installed at an intersection between two passageways (A and B) to define a first opening 105a and an overpass 105b. Air passing through the opening 105a along a first path (e.g., directions A in FIG. 1) is prevented from mixing with air traveling along a second path (e.g., directions B in FIG. 1) which includes overpass 105b. The first sidewall 102 and the second sidewall 104 are formed to be wider than the entry/opening that they are configured to block. For example, if the entry/opening width along each passageway is 16 feet, the first sidewall 102 and the second sidewall 104 may be slightly wider (e.g., 20 to 24 feet) so as to improve the air sealing qualities of the system 100.

The top member 106 is constructed to span both the entire length of the first sidewall 102 and the second sidewall 104 and the width between respective sidewalls 102, 104, thereby effectively forming the opening 105a in the first passageway A. While air moving through the second passageway B is blocked by sidewalls 102, 104 from mixing with the air moving through the first passageway A, the air moving through the second passageway B is allowed to move over the top member 106 via overpass 105b to continue along the length of the second passageway B. Optional wing walls 108, 110 may be constructed and attached upon the top member 106 to further direct air through the second passageway B and minimize air moving through the second passageway B from mixing with air moving through the first passageway A, and vice versa. Sidewalls 102, 104, top member 106, and wing walls 108, 110 may be formed of a plurality of prefabricated panels, as will be discussed hereinbelow. Furthermore, a pair of staircases 112, 114 may be installed with system 100 so as to allow personnel to traverse the overpass 105b of overcast system 100 and move through the second passageway B. While staircases 112, 114 are shown, it is to be understood that other features such as ramps, ladders, etc. may be utilized to enable travel over the overcast system 100. Details of the components of sidewalls 102, 104 and top member 106 are described hereafter.

Referring now to FIG. 2 and FIG. 3, a prefabricated panel 200 in accordance with an aspect of the present disclosure is shown. As discussed above with respect to FIG. 1, sidewalls 102, 104 and top member 106 may be produced from at least one prefabricated panel 200, a plurality of which may be interconnected to form the overcast system 100. Panel 200 includes sidewalls 202 and top side 204 and may be configured for a tongue-and-groove connection to an adjacent panel (or panels). Specifically, one end of panel 200 defines a groove 206, while the opposite end of panel 200 includes a tongue 208, thereby enabling construction of a robust and substantially air-tight connection between adjacent panels.

Panel 200 includes a wall 201 that may be formed from a thermally-efficient material, such as expanded polystyrene (EPS). Each panel 200 further includes a pair of studs, such as S-shaped studs 210, 212, which may be formed from steel. Studs 210, 212 may define openings 213 to accommodate other structural components, as described below. The openings 213 may be slots, circles, or any other shape adapted to receive the structural components. An example of such a prefabricated panel is the ACCEL-E® Steel Thermal Efficient Panel from Syntheon, Inc. (Pittsburgh, Pa.). As shown in FIG. 3, a first portion 214A of each stud 210, 212 is embedded within the panel 200, while a second portion 214B extends outside of panel 200 to form a useable stud on one of the sidewalls 202. In this way, S-shaped studs 210, 212 provide strength to the panel 200 without the need for additional reinforcements, such as rebar, wire grids, or cement coatings. Furthermore, fasteners are not needed to affix studs 210, 212 to panel 200, thereby simplifying the installation process.

Each stud 210, 212 is for example, spaced two feet apart. However, it is to be understood that the spacing of studs 210, 212 may be altered as more or fewer studs may be utilized in each panel 200. Furthermore, each panel 200 may come in standard widths (e.g., four feet), but may have customizable lengths so as to accommodate different passageway heights, spans, etc. With such standard widths, a plurality of prefabricated panels 200 may be condensed onto a single pallet to be transported through the mine passageways to the installation site, thereby reducing the time and effort needed to deliver the materials to be used in construction of an overcast system.

Referring to FIG. 4, an overcast system utilizing a plurality of panels 200 in accordance with an aspect of the present disclosure is shown. Each panel 200 is configured to be interconnected to an adjacent panel 200 via at least the tongue-and-groove connection discussed above with respect to FIG. 2. In FIG. 4, a pair of panels 200 are disposed adjacent one another so as to form each respective sidewalls 102, 104, while another pair of panels 200 are disposed adjacent one another and atop each sidewall 102, 104 so as to form a top member 106 of the overcast system 100.

Referring to FIG. 5, an “L” bracket or corner brace 116 may be fastened between the first sidewall 102 and the top member 106 and between the second sidewall 104 and the top member 106 to provide further structural reinforcement to the system 100. The corner brace 116 may be one continuous bracket spanning the length of the top member 106 or may include a plurality of brackets. The corner brace 116 may be secured to sidewalls 102, 104 and top member 106 by one or more self-tapping screws or any other suitable attachment method commonly known in the art.

To securely install the overcast system 100, C-shaped channels 118 are secured to the mine floor by extending one or more mine bolts 120, through the C-shaped channel 118 and into the mine floor F, which may be pre-drilled to receive the bolts 120. The panels 200 are then positioned in the channel 118 such as by sliding panels 200 into an open end of the C-shaped channel 118 and engaging the panels 200 thereto, for example, by extending one or more self tapping screws 215 to the studs 210, 212. The self tapping screws 215 may vary in length such that the screws 215 are secured to either the wall 201 or the studs 210, 212, or both the wall 201 and the studs 210, 212. Securing the panels 200 to the mine floor F prevents the overcast system 100 from shifting when pressure in opening 105a increases relative to overpass 105b as may occur when air flows through first passageway A.

As shown in FIG. 6, the overcast system 100 may include reinforcement structures. A pair of panels 200 having respective walls 201 are shown adjacent one another, with S-shaped studs 210, 212 extending therefrom. To more securely hold the respective panels together, one or more cross-bar connectors 215 extend between a stud 212 of one panel and a stud 210 of the adjacent panel. The cross-bar connectors 215 may have a fixed head and a terminal nut threaded thereon to engage studs 210, 212. Rotation of the terminal nut relative to the studs 210, 212 adjusts the distance between the fixed head and the terminal nut to transition the cross-bar 215 from an un-tightened position in which the cross-bar is moveable relative to the studs 210, 212 (FIG. 4 and FIG. 6) to a tightened position in which the fixed head and the terminal nut prevent movement of the cross-bar relative to the shaft to which the cross-bar 215 is attached. This assures that the panels do not separate, thereby improving the strength and air-tight qualities of the overcast structure. It is to be understood that any reasonable means of holding the adjacent panels together is suitable in accordance with the disclosure.

In addition, as shown in FIG. 6, panels 200 may be at least partially covered with wire mesh 220 disposed at or near a surface of the panels. Unlike prior art panels, the wire mesh 220 is not meant to provide increased structural integrity to the panels themselves. Instead, the wire mesh 220 may serve as a structural support for a fire-resistant spray-on coating to be added after construction of the overcast structure. The wire mesh 220 may also act to provide an increased surface area for the spray-on coating to adhere upon when applied to the overcast structure. By way of a non-limiting example, the wire mesh 220 may be attached to the steel studs 210, 212 using, for example, self-drilling screws.

The wire mesh 220 shown in FIG. 6 is shown as a 1-inch by 1-inch mesh, but it is to be understood that other forms of mesh or structural support for the spray-on coating may be used in accordance with various aspects of the disclosure. For example, referring to FIG. 7, a ribbed metal form 222 such as Stayform® available from Alabama Metal Industry Corporation (Birmingham, Ala.), may be attached to interior surfaces of panels 200 via suitable fasteners (screws, bolts or the like), not shown. Added surface members (wire mesh, metal forms, etc.) may be applied to one or more interior or exterior surfaces of panels 200. Also, while not shown, a wider mesh, such as a 4-inch by 4-inch mesh, may be used. Alternatively, no mesh or other structural support may be used, and the spray-on coating may be applied directly to the panels 200.

Referring now to FIG. 8 and FIG. 9, an overcast system 1000 having a spray-on coating is shown. As discussed above, the spray-on coating is preferably a fire-resistant coating. An example of a suitable coating is a cementitious, fiber-reinforced composite rock coating material, such as J-CRETE® from Jennmar (Pittsburgh, Pa.). J-CRETE® is a high-strength (10,000 psi) Thin Spray-on Liner (TSL) that provides sealing and flame-resistant qualities to the overcast system 1000. As shown in both FIG. 8 and FIG. 9, the spray-on coating is applied to at least a portion of and may be applied to all surfaces of overcast system 1000. Unlike previous overcast systems utilizing a concrete-based coating, the spray-on coating of overcast system 1000 does not primarily act as a structural reinforcement for the system. Rather, the spray-on coating of overcast system 1000 acts to seal and bond the prefabricated panels into a single-acting, air-tight, fire-resistant structure.

While not shown in FIG. 9, overcast system 1000 may further comprise a plurality of foam blocks placed between adjacent studs on the top side of the system prior to application of the spray-on coating. The foam blocks may be sized to provide an even and level platform surface on the top side such that after the spray-on coating is applied and cured, a suitable walking surface is formed on the top member 106 of the overcast structure 100.

Although the disclosure has been described in detail for the purpose of illustration based on what are currently considered to be the most practical and preferred aspects, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed aspects, but, on the contrary, is intended to cover modifications and equivalent arrangements. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any aspect can be combined with one or more features of any other aspect.

Claims

1. An overcast system comprising: a first sidewall formed of one or more prefabricated panels;a second sidewall formed of one or more prefabricated panels;a top member formed of one or more prefabricated panels, wherein the top member spans the width between the first sidewall and the second sidewall; anda fire-resistant coating applied to the first sidewall, the second sidewall, and the top member;wherein each of the one or more prefabricated panels is formed of a composite material having one or more structural studs embedded at least partially therein.

2. The overcast system of claim 1, wherein the composite material is expanded polystyrene (EPS).

3. The overcast system of claim 1, wherein the one or more structural studs are S-shaped steel studs.

4. The overcast system of claim 1, wherein each of the one or more prefabricated panels comprises two structural studs embedded at least partially therein.

5. The overcast system of claim 1, wherein the fire-resistant coating is fiber-reinforced composite rock coating.

6. The overcast system of claim 1, further comprising one or more wing walls attached to the top member.

7. The overcast system of claim 1, further comprising at least one of a staircase, a ramp, and a ladder.

8. The overcast system of claim 1, wherein each of the one or more prefabricated panels includes a tongue at one end thereof and defines a groove at another end thereof for receiving a tongue of another panel.

9. The overcast system of claim 1, further comprising a wire mesh applied to at least a portion of a surface of the first sidewall, the second sidewall, or the top member.

10. The overcast system of claim 1, further comprising a brace secured to the first sidewall and the top member.

11. The overcast system of claim 1, further comprising a bracket secured to a sidewall, the bracket being configured for attachment to a mine floor.

12. A method of forming an overcast system for mine ventilation, the method comprising: forming a first sidewall using one or more prefabricated panels;forming a second sidewall using one or more prefabricated panels, the second sidewall spaced apart from the first sidewall;forming a top member using one or more prefabricated panels, the top wall spanning the distance between the first sidewall and the second sidewall; andapplying a flame-resistant coating to at least a portion of the first sidewall, the second sidewall, or the top member;wherein each of the one or more prefabricated panels is formed from a composite material having one or more structural studs embedded at least partially therein.

13. The method of claim 11, further comprising securing the first and the second sidewalls into a bracket attached to a mine floor.