Underground Mine and Method of Mining

Abstract

A method of underground mining includes mining material using a continuous miner to form at least one set of entries comprising a plurality of entries. A plurality of crosscuts extend between and connect the entries. A plurality of pillars are defined by the entries and crosscuts. The entries and crosscuts define a passage having a roof, a floor, and sidewalls. The pillars at least in part are adapted to prevent the roof of the passage from collapsing. Roof bolts are installed in the roof of the passage. Material is mined from the sidewalls of the passage with the continuous miner to form perimeter cuts extending outwardly from the passage. The perimeter cuts are free of roof bolts. At least approximately 30 percent of the material mined from within the set of entries is derived from the unbolted perimeter cuts.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This divisional patent application claims priority from U.S. patent application Ser. No. 11/339,761 filed on Jan. 25, 2006, the entirety of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to an underground mine and a method of mining and more particularly to employing ventilation configurations to permit more rapid extraction of material.

The need for properly ventilating underground mines, such as underground coal mines, has long been recognized and serves two key purposes: 1) to dilute and remove potentially harmful gases (e.g., methane, carbon dioxide) and dust; and 2) to provide breathable air to the workers in the mine. Accordingly, fresh outside air is circulated along a circulation path through the mine to move gases and dust away from the face of the mine (i.e., the exposed area of a seam from which coal or ore is being extracted), and to bring breathable air to the areas of the mine in which workers may be present.

After the ventilation air passes the face of the mine it is referred to as return air. Return air carries any harmful gases and/or dust away from the face of the mine and is vented to a location outside of the mine. Mining regulations prohibit mine workers from working in the return air. This prevents workers from potentially being exposed to any harmful gases or dust that may be present in the return air. As a result, all mine workers prefer to be upstream of any extraction processes that are occurring at the mine face.

Accordingly, the circulation path of the ventilation air through the mine plays a critical role in determining the extraction process. Coal and other types of ore are typically mined using mechanical mining equipment, for example, a continuous miner. Since mine workers prefer to be upstream of the continuous miner, conventional ventilation techniques, which are described below in more detail, substantially limit the efficiencies of operating an underground mine.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a method of underground mining. The method generally comprises mining material using a continuous miner to form at least one set of entries comprising a plurality of entries, a plurality of crosscuts extending between and connecting the entries, and a plurality of pillars defined by the entries and crosscuts. The entries and crosscuts define a passage having a roof, a floor, and sidewalls. Roof bolts are installed in the roof of the passage. Material is mined from the sidewalls of the passage with the continuous miner to form perimeter cuts extending outwardly from the passage. The perimeter cuts are free of roof bolts. At least approximately 30 percent of the material is mined from within the set of entries being derived from the unbolted perimeter cuts.

Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing part of an underground mine, portions of the mine are shown in phantom indicating areas that have not yet been mined;

FIG. 1A is an enlarged detail of the circumscribed portion of FIG. 1;

FIG. 1B is an enlarged detail of the circumscribed portion of FIG. 1;

FIG. 2 is a schematic of the part of the underground mine showing a known ventilation configuration;

FIG. 2A is an enlarged detail of the circumscribed portion of FIG. 2;

FIG. 3 is a schematic of the part of the underground mine showing another known ventilation configuration;

FIG. 3A is an enlarged detail of the circumscribed portion of FIG. 3;

FIG. 4 is a schematic of part of an underground mine showing one ventilation configuration in accordance with the present invention;

FIG. 4A is an enlarged detail of the circumscribed portion of FIG. 4;

FIG. 5 is a schematic of the part of the underground mine showing a second ventilation configuration in accordance with the present invention;

FIG. 5A is an enlarged detail of the circumscribed portion of FIG. 5;

FIG. 6 is a schematic showing part of an underground mine having sets of perimeter wall entries;

FIG. 6A is an enlarged detail of the circumscribed portion of FIG. 6;

FIG. 7 is a schematic of the part of the underground mine of FIG. 6 showing a third ventilation configuration in accordance with the present invention;

FIG. 7A is an enlarged detail of the circumscribed portion of FIG. 7;

FIG. 8 is a schematic of the part of the underground mine of FIG. 6 showing a fourth ventilation configuration in accordance with the present invention;

FIG. 8A is an enlarged detail of the circumscribed portion of FIG. 8;

FIG. 9 is a schematic of part of an underground mine showing yet another ventilation configuration in accordance with the present invention;

FIG. 9A is an enlarged detail of the circumscribed portion of FIG. 9;

FIG. 10 is a schematic of the part of the underground mine of FIG. 10 showing a still another ventilation configuration in accordance with the present invention; and

FIG. 10A is an enlarged detail of the circumscribed portion of FIG. 10.

Corresponding reference characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and in particularly to FIG. 1. FIG. 1 shows a portion of an underground mine advanced into a coal seam including a panel development, indicated generally at 10, extending outwardly from a set of main entries, indicated generally at 12. A portion of the coal mine is shown in phantom to indicate areas that are planned to be mined but have not yet been mined. While the invention is described herein with reference to a coal mine, it is understood that the present invention can be used in other types of underground mines.

The set of main entries 12 includes main entries 14 and main crosscuts 16 extending between the main entries. The main entries 14 and main crosscuts 16 cooperate to define a plurality of pillars 18. The set of main entries 12 is shown in FIG. 1 truncated as it is understood that the set of main entries can include any number of main entries 14 and any number of crosscuts 16. The main entries 14 can extend indefinitely. In some mines, the main entries 14 extend for a mile or more.

The main entries 14 are tunnels formed during the coal extraction process that serve as passages in the mine for subsequent mining operations. In short, they are the main arteries used to transport mine workers, equipment, and/or coal into and out of the underground mine. In the illustrated configuration, the passages defined by both the main entries 14 and the main crosscuts 16 are approximately 20 feet wide. But the width of the passages can be greater or less than that illustrated. The width of the passages defined by the main entries 14 can also be greater or less than the width of the passages defined by the main crosscuts 16.

The set of main entries 12 can be divided into sets of sub-main entries (not shown), which are branches extending from the set of main entries, to access a portion of the mine. In short, the set of main entries 12 can be used to access all or most of the mine whereas the set of sub-main entries feed off of the set of main entries and are used to access only a portion of the mine. The distinction between sets of main entries and sets of sub-main entries is not germane to the present invention. Thus, sets of main entries and sets of sub-main entries are grouped herein simply as sets of main entries 12.

The pillars 18 are portions of the mined coal seam that are left in place to keep the passages open during mining and to prevent subsidence of the overlying surface. The pillars 18 prevent the roof of the mine from collapsing because of the weight of the overburden. For example, the pillars 18 defined by the main entries 14 and main crosscuts 16 in the illustrated configuration are approximately 60 feet by 60 feet. The pillars 18 are about 20 feet apart in both a longitudinal direction and a lateral direction. It is understood that the pillar size, shape, and spacing can be different.

Referring to FIG. 1A, roof supports, such as roof bolts 20, are typically installed in the roof in the passages defined by the main entries 14 and the crosscuts 16 (i.e., between the pillars 18) to assist in supporting the roof of the mine. Roof bolts 20 are long steel bolts (e.g., 4 feet) driven into the overburden defining the roof of the mine to support the roof. Basically, the bolts 20 fasten portions of the overburden together and stabilize the roof. Installing roof bolts 20 is both costly and dangerous as it requires mine workers to enter portions of the mine that are supported only by the pillars 18. Other roof supports (not shown), such as timbers, posts, and jacks, may also be used to support the mine roof.

Referring again to FIG. 1, extending outwardly from the set of main entries 12 is the panel development 10, which includes a set of panel entries, indicated generally at 22, and a plurality of sets of rooms, indicated generally at 33. In the illustrated configuration, the set of panel entries 22 comprises seven panel entries 24, and a plurality of panel crosscuts 26 forming passages through the panel development 10. The length of the panel entries 24, like the main entries 14, is indefinite but is commonly less than the distance of the main entries. For example, the panel entries 24 of the illustrated configuration, including the portions shown in phantom, are approximately 2,000 feet when fully advanced. Roof bolts 20 are installed in the roof of the passages defined by the panel entries 24 and panel crosscuts 26 in the same manner as described above with respect to the set of main entries 12.

The panel entries 24 and panel crosscut 26 cooperatively define a plurality of panel pillars 28. The panel pillars 28 in the illustrated panel development 10 are the same size as those in the set of main entries 12. It is understood, however, that the panel pillars 28 can be smaller or larger than the main pillars 18. It is also understood that the panel pillars 28 can have different shapes and sizes, and account for more or less of the coal seam than shown herein.

With reference still to FIG. 1, five of the panel entries 24 are interior entries B-F having panel pillars 28 on both sides of the panel entries and the remaining two panel entries are exterior entries A, G. That is, they have panel pillars 28 on one side and a longitudinal sidewall 30 defined by the coal seam on the opposite side. In addition, one of the panel crosscuts 26 (i.e., the crosscut at the furthest extent of the panel development) defines an end wall 32 of the panel development 10. The other panel crosscuts 26 are interior crosscuts having panel pillars 28 on both sides.

Extending outwardly from the sidewall 30 of the panel entries 24 are the plurality of sets of rooms 33 comprising rooms 34, crosscuts 36 connecting the rooms, and pillars 38 defined by the rooms and the crosscuts. Sixteen sets of rooms 33 are shown extending outwardly from the panel entries 24 but it is understood that more or fewer rooms can be advanced off of the panel entries 24. Moreover, eight of the sixteen sets of rooms 33 extend to the left of the panel entries 24 (as view in FIG. 1) and eight sets of rooms extend to the right. It is understood, however, that the number of rooms extending to the right and left of the panel entries 24 can be different. While the sets of rooms 33 are shown extending outwardly from the set of panel entries 22 it is understood that the sets of rooms can extend outwardly from the set of main entries 12.

A portion of the panel development 10 illustrated in FIG. 1 is shown in phantom to indicate portions of the mine planned to be mined but which have not yet been mined. The portions of the panel development 10 shown in solid line indicated portions of the mine that have already been mined. The panel development 10 could have been mined to its current state by advancing the set of panel entries 22 to a location slightly beyond where a first set of rooms 33′ have been advanced outwardly from the set of panel entries. The first set of rooms 33′ extending outwardly from the set of panel entries 22 to the left as viewed in FIG. 1 were fully mined. The set of panel entries 22 were then advanced to location slightly beyond where a second set of rooms 33′ were advanced outwardly from the set of panel entries. The second set of rooms 33″ on the left side of set of panel entries were fully mined and then the set of panel entries were advanced to a location beyond the next set of rooms 33 as shown in FIG. 1. The process of advancing the set of panel entries 22 and completing sets of rooms 33 is continued until the set of panel entries is fully advanced and all of the rooms on the left side of the set of panel entries are fully mined as shown in phantom in FIG. 1. Next, the rooms on the right side of the set of panel entries 22 are completed starting with the set of rooms 33 closest to the end wall 32 and ending with the set of rooms closest the set of main entries 12.

The number of rooms 34 in each set of rooms 33 can be different. As illustrated, most of the sets of rooms 33 have four rooms 34 but it is understood that the sets of rooms can have more or fewer rooms. For example, the first set of rooms 33′ has only two rooms H, I. The second set of rooms 33″ has three rooms J, K, L. In the illustrated configuration, the rooms 34 extended outwardly from the sidewalls 30 of the panel 24 approximately 300 feet. The rooms 34 can be extended up to a regulatory maximum distance of 600 feet or can be shorter than 300 feet.

The room pillars 38 are smaller than the main pillars 18 and the panel pillars 28. Thus, more coal is extracted from the coal seam in the sets of rooms 33 than from the set of main entries 12 or set of panel entries 22. More particularly, the room pillars 38 are approximately 30 feet by 40 feet. The room pillars 38, like the main pillars 18 and the panel pillars 28, are spaced apart approximately 20 feet in both the longitudinal and lateral directions. It is understood that the room pillars 38 can have different sizes, shapes, and spacing than those illustrated. The roof of the mine between the room pillars 28 (i.e., in the passages defined by the rooms 34 and room crosscuts 36) is supported using roof supports (e.g., roof bolts 20).

In the illustrated configuration, coal is extracted from longitudinal sidewalls 40 and an end wall 42 of each set of rooms 33. The void in the coal seam created by extracting coal from the longitudinal sidewall 40 or end wall 42 is referred to as a perimeter cut 44. The perimeter cuts 44 formed in the end wall 42 and sidewalls 42 are generally orthogonal to the end wall and sidewalls, respectively. In the illustrated mine, the cuts 44 are approximately 20 feet wide and approximately 40 feet long but can have other widths and lengths. The coal extracted from the perimeter cuts 44 account for about 20 percent to about 23 percent of the total coal extracted from each of the sets of rooms 33. Roof bolts 20 are preferably not used within the cut 44.

The height of the perimeter cuts 44 corresponds generally to the thickness of the coal seam. In the set of main entries 12, set of panel entries 22, and sets of rooms 33 (i.e., rooms 34 and room crosscuts 36), on the other hand, rock overlying and/or underlying the coal seam is often removed to provide sufficient clearance for allowing equipment and workers to pass through the entries. The removal of rock significantly increases production costs by allocating mining resources and efforts to the removal a rock, which is a liability and not a commodity, like the coal. Moreover, the overlying and underlying rock is typically harder and heavier than the coal, making it more difficult to mine and handle. Furthermore, the rock is often dumped in a gob pile, which has to be managed and takes up substantial land space.

During the mining process, a continuous miner 46 extracts coal and/or rock from the face of the mine. The extracted coal and/or rock is transported from the continuous miner 46 to a conveyor belt 48 using battery-powered haulers (not shown). The conveyor belt 48 transfers the extracted materials to the surface. Typically, the conveyor 48 runs through the set of main entries 12 and set of panel entries 22 to a location in relatively close proximity to the face of the mine so that as coal is extracted it needs to be transported by one of the haulers only a short distance before being loaded onto the conveyor belt. The distance between the face of the mine and conveyor belt 48 is often minimized to keep the hauler trips short. The conveyor belt 48 is typically not extended into the sets of rooms 33 because of the relatively short length of the rooms 34.

As illustrated in FIG. 1B, to advance the set of main entries 12, set of panel entries 22, or rooms 34 coal is extracted a short distance (e.g., between 10 feet and 40 feet) using the continuous miner 46 in one of the entries or rooms to form a short, unsupported area. The continuous miner 46 is then moved to an adjacent entry 12, 22 or room 34 to do the same. While the continuous miner 46 is extracting coal from the adjacent entry 12, 22 or room 34, mine workers install roof bolts 20 in the previously extracted area. This alternating process is continued until the entry 12, 22 or room 34 is advanced the desired distance. For example, in FIG. 1B, rooms P, O, N have been advanced approximately 20 feet from the nearest crosscut 36 using the continuous miner 46 and roof bolts 20 have been installed in two of the rooms P, O. Roof bolts 20 are being installed in the third room N, which is shown as completely installed in FIGS. 2A and 3A. Referring again to FIG. 1B, the continuous miner 46 is shown advancing room M. The continuous miner alternates mining the rooms P-M until the rooms are advanced beyond where one of the room crosscuts 36 is to be formed, and then the crosscut is made and roof bolted. After the crosscut 36 is completed, the rooms P-M are advanced until the next crosscut 36 needs to be made. This process is continued until the set of rooms 33 are fully advanced. Once one of the sets of rooms 33 is fully advanced, the perimeter cuts 44 are made using the continuous miner 46 as shown in FIG. 2.

The mining operation is carefully planned to ensure that gas ignitions are prevented and the mine workers have fresh air to breathe and are not exposed to any potential harmful gases or dust that may be produced at the face of the mine. As illustrated in FIG. 1, this is done by directing intake air to move along a predetermined air circulation pathway through the mine.

In FIG. 1, which illustrates a conventional ventilation technique, three panel entries E-G are used to supply fresh air (commonly called “intake air”) to the mine face and two of the panel entries A, B are used as air returns for exhausting any potential gases (e.g., methane) and/or dust from the area of the mine being mined by the continuous miner 46 (i.e., the face of the mine). Two of the interior panel entries C, D are neutral and are used for hauling coal from the mine via the conveyor belt 48 and for transporting mine workers into and out of the mine.

The panel entries E-G with intake air are separated from the neutral panel entries C, D and the neutral panel entries are separated from the panel entries A, B with return air using barriers. The barriers are used to direct air flow in a desired circulation path through the mine. The illustrated barriers include a plurality of stoppings 50 and a plurality of curtains 52. Stoppings 50, which are typically concrete block or metal panels, and curtains 52, which are typically sheet material (e.g., plastic, cloth), are extended between the main pillars 18, the panel pillars 28, and/or the room pillars 38 to direct air flow through the set of main entries 12, set of panel entries 22, and/or one of the sets of rooms 33, respectively. Typically, only curtains are used in the sets of rooms 33.

In the configuration illustrated in FIGS. 1 and 2, intake air is directed using curtains 52 through the main entries 14 into the panel entries 24 and into one of the sets of the rooms 33 so that the intake air passes the face of the mine. The path of the intake air is shown in the Figures using arrows. Since each of the sets of rooms 33 are mined and vented in substantially the same way, only the mining and venting of only one set of rooms is described.

In the illustrated configuration, intake air enters the panel development 10 and is directed through panel entries E-G using curtains 52. Curtains are also used to direct the intake air through one of the panel crosscuts 26 and into one of the sets of rooms 33. The intake air is directed using curtains 52 through room P and through one of the room crosscuts 36 where it passes the continuous miner 46 (i.e., the face of the mine) thereby entraining any potential harmful gases or dust. After passing the face of the mine, the air is referred to as return air and is represented in the drawings by two-headed arrows. The return air exits through room M and into panel entries A, B where it is directed using stoppings 50 to exit the panel development 10 into the set of main entries 12 and then to a vent location (not shown) located outside of the mine. Air is directed through the circulation pathway using a fan (not shown). The fan can be used to either force or draw air through the circulation pathway.

As mentioned above, mining regulations prohibit mining activities in the return air. As a result, only one continuous miner 46 can operate in the set of rooms 33 when the air circulation technique illustrated in FIGS. 1 and 2 is used.

A second continuous miner 46 can be used if the ventilation air is circulated through the mine as shown in FIG. 3. In this known ventilation configuration (sometimes referred to as “fishtailing”) intake air is directed using both stoppings 50 and curtains 52 to flow through the main entries 14, through two of the interior panel entries E, F and is split into two intake air flows within the set of panel entries 22. As a result of the split intake air flow, sets of rooms 33 on opposite sides of the set of panel entries 22 can be supplied intake air. As a result, continuous miners 46 can be used or other mining operations can be preformed in each of the sets of rooms 33 with intake air. In the illustrated configurations, two continuous miners 46 are being used to perform perimeter cuts 44. After the intake air passes the continuous miners 46 and becomes return air, the return air flows through one of the rooms M, M′ in each of the sets of rooms 33 to which intake air was directed. After leaving the set of rooms 33, the return air flows through the panel entries A, B located adjacent the left side of the set of panel entries 22 (as viewed in FIG. 3), or through the exterior panel entry G located adjacent the right side of the set of panel entries. Two of the interior panel entries C, D are neutral and contain the conveyor belt 48 for transferring coal from the near the face of the mine to the surface. As compared to the ventilation configuration illustrated in FIGS. 1 and 2, the ventilation configuration shown in FIG. 3 requires additional ventilation controls (i.e., more stoppings 50 and/or curtains 52) because two air returns are used instead of one.

FIG. 4 shows a panel development 110 that is similar to the panel development 10 described above with reference to FIGS. 1-3. More specifically, the set of main entries 112 and the set of panel entries 122 are substantially the same as the set of main entries 12 and set of panel entries 22, respectively. Corresponding parts of the set of main entries 112 and set of panel entries 122 are indicated by the same reference numbers used in FIGS. 1-3 plus “100”.

Extending outwardly from each of the sidewalls 130 of the set of panel entries 122 are numerous sets of perimeter wall entries 133 comprising perimeter wall entries 134, perimeter wall crosscuts 136 connecting the perimeter wall entries 134, and perimeter wall pillars 138 defined by the perimeter wall entries and the perimeter wall crosscuts. As before, the parts shown in phantom indicate proposed excavations whereas solid lines indicate areas already mined. Sixteen sets of perimeter wall entries 133 are shown extending outwardly from the set of panel entries 122 but it is understood that more or fewer perimeter wall entries can be advanced off of the set of panel entries. Moreover, eight of the sixteen sets of perimeter wall entries 133 extend to the left of the set of panel entries 122 (as view in FIG. 4) and eight sets of perimeter wall entries extend to the right. It is understood, however, that the number of perimeter wall entries extending to the right and left of the set of panel entries 122 can be different. While the sets of perimeter wall entries 133 are shown extending outwardly from the set of panel entries 122 it is understood that the sets of perimeter wall entries can extend outwardly from the set of main entries 112.

The number of perimeter wall entries 134 in each set of perimeter wall entries 133 can be different. As illustrated, most of the sets of perimeter wall entries 133 have four perimeter wall entries 134 but it is understood that the sets of perimeter wall entries can have more or fewer perimeter wall entries. For example, the first set of perimeter wall entries 133′ has only two perimeter wall entries H, I. The second set of perimeter wall entries 133″ has three perimeter wall entries J, K, L. In the illustrated configuration, the perimeter wall entries 133 extended outwardly from the sidewalls 130 of the set of panel entries 122 approximately 300 feet. The set of perimeter wall entries 133 can be extend well beyond 300 feet (i.e., 1,000 feet or more) or can be shorter than 300 feet.

The perimeter wall pillars 138 are smaller than the main pillars 118 and the panel pillars 128. Thus, more coal is extracted from the coal seam in the sets of perimeter wall entries 133 than from the set of main entries 112 or set of panel entries 122. More particularly, the perimeter wall pillars 138 are approximately 30 feet by 40 feet. The perimeter wall entries pillars 138, like the main pillars 118 and the panel pillars 128, are spaced apart approximately 20 feet in both the longitudinal and lateral directions. It is understood that the perimeter wall pillars 138 can have different sizes, shapes, and spacing than those illustrated. The roof of the mine between the perimeter wall pillars 128 (i.e., in the passages defined by the perimeter wall entries 134 and perimeter wall crosscuts 136) is supported using roof supports (e.g., roof bolts 120).

In the illustrated configuration, coal is extracted from longitudinal sidewalls 140 and an end wall 142 of each set of perimeter wall entries 133. The void in the coal seam created by extracting coal from the longitudinal sidewall 140 or end wall 142 is referred to as a perimeter cut 144. The perimeter cuts 144 formed in the end wall 142 adjacent the perimeter wall entries 134 are generally perpendicular to the end wall whereas the cuts formed in the end wall between the perimeter wall entries and in the sidewalls 140 are generally oblique to the end wall and sidewalls, respectively. The perimeter cuts 144 are formed this manner for convenience in using the mining equipment. The continuous miners 146 can more quickly mine the perimeter cut 144 when it is angled with respect to the end wall 142 and sidewalls 140 than when it is at a right angle. The angle between the perimeter cuts 144 and the sidewalls 140 and/or end wall 142 can be different than those shown. In the illustrated mine, the perimeter cuts 144 are approximately 20 feet wide and approximately 40 feet long but can have other widths and lengths. The height of the perimeter cuts 144 corresponds generally to the thickness of the coal seam. Roof bolts 120 are preferably not used within the cut 144.

A mine ventilation system in accordance with the presence invention is shown in FIGS. 4 and 4A wherein two continuous miners 146 can be used in the same set of perimeter wall entries 133 while making the perimeter cuts 144 into the sidewalls 140 or end walls 142 of the set of perimeter wall entries. Being able to operate two continuous miners in the same set of perimeter wall entries 133 as compared to one continuous miner is a significant advantage in the art of mining. For one, the rate at which the coal can be extracted can be significantly increased.

As illustrated in FIG. 4, intake air is directed using curtains 152 through the main entries 114 into the panel entries E-G and then into one of the sets of perimeter wall entries 133 so that the intake air passes the face of the mine. The intake air is directed through at least two of the perimeter wall entries M, P. The other two perimeter wall entries N, 0 in this configuration are neutral. However, intake air could be supplied to all four of the perimeter wall entries 134. The flow rate of the intake air can be regulated using the curtains 152 so that the flow rate is equal in each of the perimeter wall entries 134 having intake air supplied thereto. The flow rate could also be regulated so that it is different in one or more of the perimeter wall entries 134. One way to regulate the flow rate of the intake air is to partially open one or more of the curtains 152.

The intake air is directed past the two continuous miners 146 (i.e., the face of the mine) thereby entraining any potential harmful gases or dust. After passing the face of the mine, the return air, is directed out of the set of perimeter wall entries 133 through a bleed pathway 154 to one or more of the previously mined sets of perimeter wall entries 133′, 133″. It is understood that more than one bleed pathway 154 could be used. The return air then flows out of the set(s) of perimeter wall entries 133′, 133″ feed by the bleed pathway 154, through the panel entries A, B and through the main entries 114 to the vent location (not shown) located outside of the mine.

In the configuration illustrated in FIG. 4A, the perimeter cuts 144 in the end wall 142 are identified as EW1-EW10, and the perimeter cuts in the sidewalls 140 are identified as SW1-SW7 and SW1′-SW7′. Perimeter cuts EW1-EW10, SW1 and SW1′ and the bleed pathway 154 have already been completed and the continuous miners 146 are shown mining perimeter cuts SW2 and SW2′. The bleed pathway 154 was completed first followed by the perimeter cuts EW1-EW10 in the end wall 142 by starting in perimeter cut EW1 and working in consecutive order toward perimeter cut EW10 using one of the continuous miners 146. Once the continuous miner advanced beyond perimeter cut EW5, the second continuous miner 146 began on perimeter cut SW1. Perimeter cuts SW1-SW7 and SW1′ and SW7′ are also advance in consecutive order being with SW1 and SW1′.

FIG. 5 shows another configuration wherein four continuous miners 146 can be used to make perimeter cuts 44 within two sets of perimeter wall entries 133. Intake air is directed using both stoppings 150 and curtains 152 to flow through the main entries 114, through panel entries E, F and is split into two intake air flows within the set of panel entries 122. As a result of the split, one or more sets of perimeter wall entries 133 on each side of the set of panel entries 122 can be supplied intake air. The illustrated configuration shows one set of perimeter wall entries 133 located on each side of the set of panel entries 122 being supplied intake air. The intake air is directed through at least two of the perimeter wall entries P, P′, M, M′ in each set of perimeter wall entries 133. The intake air is directed past all four continuous miners 146 (i.e., the face of the mine) thereby entraining any potential harmful gases or dust. After passing the face of the mine, the return air, is directed out of each set of perimeter wall entries 133 through a bleed pathway 154 to one or more previously mined sets of perimeter wall entries. The return air flows out of the previously mined sets of perimeter wall entries 133, through a respective one of two exterior panel entries A, G. One of the exterior panel entries A is located adjacent the left side of the set of panel entries 22 (as viewed in FIG. 5), and the other exterior panel entry G is located adjacent the right side of the set of panel entries.

FIG. 6 shows multiple sets of perimeter wall entries, indicated generally at 162, that are substantially longer than the sets of perimeter wall entries 133 shown in FIGS. 4-5A. Each set of perimeter wall entries 162 comprises perimeter wall entries 164, perimeter wall crosscuts 166 connecting the perimeter wall entries, and pillars 168 defined by the perimeter wall entries and the perimeter wall crosscuts. In the illustrated configuration, the perimeter wall entries 164 extend outwardly from the sidewalls 130 of the panel 124 approximately 540 feet. However, the perimeter wall entries 164 can extend over several thousand feet or more.

FIGS. 6 and 6A illustrate how the sets of perimeter wall entries 162 are advanced. As shown only one of the continuous miners 146 is being used to mine. Coal is extracted a short distance (e.g., between 10 feet and 40 feet) using the continuous miner 146 in one of the perimeter wall entries to form a short, unsupported area, such as is shown in perimeter wall entries P, O. The continuous miner 146 is then moved to the adjacent perimeter wall entry N to do the same. While the continuous miner 146 is extracting coal from the adjacent perimeter wall entry N, mine workers can install roof bolts 20 in the previously mine perimeter wall entries P, O. This alternating process is continued until the set of perimeter wall entries 162 are advanced to the desired distance. A second continuous miner 146 is shown idle. It is understood, however, that only one continuous miner 146 can be used or that the two continuous miners can alternate between mining and idling while the set of perimeter wall entries 162 is being advanced. This alternating process is continued until the set of perimeter wall entries 162 is fully developed.

While the perimeter wall entries 164 are being advanced, a conveyor belt 148 is extended into one of the perimeter wall entries O, which is neutral, so that as the coal (or rock) is extracted it can be transported from the continuous miner 146 to the conveyor belt using motorized haulers (not shown). As a result, the conveyor 148 is kept in relatively close proximity to the face of the mine so that as coal is extracted it needs to be transported by a hauler only a short distance before being loaded onto the conveyor belt. Stoppings 150 and curtains 152 are also installed in the set of perimeter wall entries 162 to direct air flow.

FIGS. 7 and 7A show a mine ventilation system of another configuration wherein two continuous miners 146 can operate or other mining operations can be performed in the same set of perimeter wall entries 162 while making the perimeter cuts 144 into the sidewalls 170 or end walls 172 of the set of perimeter wall entries. As illustrated in FIG. 7, intake air is directed using stoppings 150 through the main entries 114, through the panel entries 124 and into one of the sets of perimeter wall entries 162 so that the intake air passes the face of the mine. As shown, stoppings 150 are located in the set of perimeter wall entries 164 to which intake air is directed.

Perimeter cuts 144 can be made within one set of perimeter wall entries 162 using the two continuous miners 146 as shown in FIGS. 7 and 7B. The intake air is directed into one of the perimeter wall entries P but is split to flow through one of the perimeter wall crosscuts 166 before it passes any of the continuous miners 146 so that intake air is supplied to the opposing perimeter wall entry M. Thus, intake air is supplied to both continuous miners 146 while making cuts 144 into opposite sidewalls 170 of the perimeter wall entries 162. The intake air is directed past both of the continuous miner 146 (i.e., the face of the mine) thereby entraining any potential harmful gases or dust. After passing the continuous miner 146 in perimeter entry P, the return air, is directed out of the set of perimeter wall entries 162 through the bleed pathway 154 to one or more previously mined sets of perimeter wall entries. The intake air diverted through the perimeter wall crosscut 166 past the continuous miner 146 in perimeter entry M and is exhausted through two of the panel entries A, B. The return air then flows through the main entries 114 to the vent location (not shown) located outside of the mine.

The perimeter cuts 144 along the sidewalls 170 of set of perimeter wall entries 162 are made starting with the cut nearest the end wall 172 and working toward the set of panel entries 122. The cuts 144 in the end wall 172 are made before the cuts in the sidewall 170. As the continuous miners 146 work their way toward the set of panel entries 122, the stoppings 150, curtains 152, and/or conveyor belt 148 are disassembled in advance of the continuous miners so that the stoppings, curtains, and conveyor belt do not interfere with the mining process and to ensure proper air flow at the face of the mine.

As shown in FIG. 7A, roof bolts 120 are not used within the cut 144. In the configuration illustrated in FIG. 7, approximately 30 percent of the coal mined from within the set of perimeter wall entries 162 having four perimeter wall entries 164 is done so from unbolted portions of the mine. The percentage of unbolted area within the set of perimeter wall entries 162 can be increased by advancing fewer perimeter wall entries 164 per set. For example, in the set of perimeter wall entries 162 having three perimeter wall entries 164, the unbolted area of the set of rooms increases to about 37 percent. In the set of perimeter wall entries 162 with only two perimeter wall entries 164, the area of the set of perimeter wall entries that is mined and unbolted is approximately 48 percent. Accordingly, mining operations having perimeter cuts 144 is significantly more economical than mining operations without cuts. Moreover, the greater the distance of the perimeter wall entries 164 the greater number of perimeter cuts 144 that can be made in the set of perimeter wall entries.

FIGS. 8 and 8A show a ventilation system having yet another configuration wherein two continuous miners 146 can be used to make perimeter cuts 144 within adjacent sets of perimeter wall entries 162 on the same side of the panel development 110. Intake air is directed using both stoppings 150 and curtains 152 to flow through the main entries 114, through three of the panel entries E, F, G and through one of the panel crosscuts 126. The intake air is split into two flow paths in one of the exterior panel entries A and is directed into two adjacent sets of perimeter wall entries 162. The intake air is directed so that at least two of the perimeter wall entries J, L, M, P within each of the two sets of perimeter wall entries 164 have intake air flowing through them in the same direction. As a result, the intake air entrains and carries away any potential harmful gases or dust generated by the two continuous miners 146. It is understood that each of the sets of perimeter wall entries 162 could have two continuous miners 146 (for a total of four continuous miners) as shown in FIG. 7. It is also understood the intake could be split so that it supplies intake air to sets of perimeter wall entries 162 on opposite sides of set of panel entries 122 as shown in FIG. 5 to allow up to eight continuous miners 146 to be used within the same panel development 110.

After passing the face of the mine, the return air, is directed out of each set of perimeter wall entries 162 through the bleed pathway 154 to one or more of the previously mined sets of perimeter wall entries 162. The return air flows out of the previously mined set(s) of perimeter wall entries 162, through two panel entries A, B and through the set of main entries 112 to the vent location located outside of the mine.

FIGS. 9, 9A, 10, and 10A show a method of mining that allow two continuous miners 146 to be operated simultaneously during the development of the panel development 110. In this method, one of the continuous miners 146 is used to advance the set of panel entries 122 off of the set of main entries 112. Once the continuous miner 146 advances the set of panel entries 122 far enough away from the set of main entries 112, the other continuous miner 146 can be used to advance the sets of perimeter wall entries 162. For example, as shown in FIGS. 9 and 9A, one of the continuous miners 146 was used to advance the set panel entries 122 to approximately half of its intended depth, and the other continuous miner 146 was used to advance the first three perimeter wall entries 162 on the left side of the set of panel entries 122. More specifically, FIGS. 9 and 9A show one of the continuous miner 146 being used to make perimeter cuts 144 within one of the sets of perimeter wall entries 162 while the other continuous miner 146 is being used to advance the set of panel entries 122. The two continuous miners 146 can be operated simultaneously.

In this configuration, intake air is directed using both stoppings 150 and curtains 152 to flow through the main entries 114, through two of the panel entries E, F and through one of the panel crosscuts 126. The intake air is split into two flow paths in one of the exterior panel entries A. One of the intake air flow paths is directed into one of the sets of perimeter wall entries 162. The intake air is directed so that it passes the continuous miner 146 to entrain and carry away any potential harmful gases or dust generated by the continuous miner 146. The intake air is directed to flow through at least one of the perimeter wall entries P. It is understood that two continuous miners 146, as shown in FIGS. 7 and 7A, could be used to make the perimeter cuts 144. After passing the continuous miner 146, the return air is directed out of the set of perimeter wall entries 162 through the bleed pathway 154 to one or more of the previously mined sets of perimeter wall entries 162. The return air flows out of the previously mined set(s) of perimeter wall entries 162, through two panel entries A, B and through the set of main entries 112 to the vent location located outside of the mine.

The other intake air split is directed through one of the panel entries A to the leading panel crosscut 126 where it can pass the other continuous miner 164 that is being used to advance the set of panel entries 122. After the intake air passes the continuous miner 146 it entrains and carries away any potential harmful gases or dust generated by the continuous miner. The return air is directed out of the set of panel entries 122 through one of the exterior panel entries G. The return air flows out of panel entry G through the set of main entries 112 to the vent location located outside of the mine.

As the set of panel entries 122 is advanced, the conveyor belt 148 is extended further into the set of panel entries so that the conveyor 148 is kept in relatively close proximity to the face of the mine. Thus, as coal is extracted it needs to be transported by a hauler only a short distance before being loaded onto the conveyor belt 148. Additional stoppings 150 and/or curtains 152 are also installed in the set of panel entries 122 to maintain the desired air flow.

After the sets of perimeter wall entries 162 on the left side of the panel development 110 and the set of panel entries 122 have been fully advanced, the sets of perimeter wall entries on the right side of the panel development (as viewed in FIG. 10) are mined in a retreating fashion. That is, the sets of perimeter wall entries 162 are mined starting with the set of perimeter wall entries located farthest from the set of main entries 112 and working sequentially toward to the set of main entries. As the sets of perimeter wall entries 162 are completed, the conveyor belt 148 is disassembled. Moreover, the stoppings 150 and/or curtains 152 are moved or disassembled as necessary to maintain the desired air flow through the panel development 110.

FIGS. 10 and 10A illustrate a method of mining the sets of perimeter wall entries 162 on the right side of the panel development 110. In this configuration, two continuous miners 146 are being used to make perimeter cuts 144 within adjacent sets of perimeter wall entries 162 on the same side of the panel development 110. It is understood that the two continuous miners 146 can be used simultaneously to advance perimeter wall entries 164 and perimeter wall crosscuts 166 in adjacent sets of perimeter wall entries 162. In the illustrated configuration, intake air is directed using both stoppings 150 and curtains 152 to flow through the main entries 114, through two of the panel entries E, F and through one of the panel crosscuts 126. The intake air is split into two flow paths in one of the exterior panel entries G and is directed into two adjacent sets of perimeter wall entries 162. The intake air is directed so that at least one of the perimeter wall entries 164 within each of the two sets of perimeter wall entries 162 have intake air flowing through them in the same direction. In the illustrated configuration, the intake air is directed into all four of the perimeter wall entries 162 in each of the two sets of perimeter wall entries 164. As a result, the intake air entrains and carries away any potential harmful gases or dust generated by the two continuous miners 146. It is understood that each of the sets of perimeter wall entries 162 could have two continuous miners 146 (for a total of four continuous miners) as shown in FIG. 7 for making the perimeter cuts 144.

After passing the continuous miners 146, the return air, is directed out of each set of perimeter wall entries 162 through the bleed pathway 154 toward the previously mined sets of perimeter wall entries 162. In other words, the return air is directed away from the set of main entries 112. The return air flows out of the previously mined set(s) of perimeter wall entries 162, through at least one panel crosscut 126 and into one of the sets of perimeter wall entries 162 on the opposite side (i.e., the left side) of the panel development 110. The return is further directed through the bleed pathway 154, through the set of perimeter wall entries 162 nearest the set of main entries 112, through two of the panel entries A, B, and through the set of main entries 112 to the vent location located outside of the mine.

It is understood that some or all of the perimeter wall pillars 138, the panel pillars 128, and/or the main pillars 118 may be extracted (often called “pillaring”) causing the overlying surface to subside, or may be left in place as a permanent support for the overlying surface.

Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

1. A method of underground mining comprising:

mining material using a continuous miner to form at least one set of entries comprising a plurality of entries, a plurality of crosscuts extending between and connecting the entries, and a plurality of pillars being defined by the entries and crosscuts, the entries and crosscuts defining a passage having a roof, a floor, and sidewalls, the pillars at least in part being adapted to prevent the roof of the passage from collapsing;

installing roof bolts in the roof of the passage; and

mining material from the sidewalls of the passage with the continuous miner to form perimeter cuts extending outwardly from the passage, the perimeter cuts being free of roof bolts, at least approximately 30 percent of the material mined from within the set of entries being derived from the unbolted perimeter cuts.

2. A method as set forth in claim 1 wherein material is mined to form at least one set of perimeter wall entries comprising a plurality of perimeter wall entries, a plurality of perimeter wall crosscuts, and a plurality of perimeter wall pillars.

3. A method as set forth in claim 2 wherein material is mined to form four perimeter wall entries.

4. A method as set forth in claim 2 wherein material is mined to form three perimeter wall entries.

5. A method as set forth in claim 2 wherein material is mined to form two perimeter wall entries.

6. A method as set forth in claim 2 wherein at least approximately 37 percent of the material mined from the set perimeter wall entries is derived from the unbolted perimeter cuts.

7. A method as set forth in claim 2 wherein at least approximately 48 percent of the material mined from the set perimeter wall entries is derived from the unbolted perimeter cuts.

8. A method as set forth in claim 1 wherein the entries are formed to have a length greater than 600 feet.

9. A method as set forth in claim 1 wherein a plurality of continuous miners is operated in the set of entries to form the perimeter cuts.

10. A method as set forth in claim 9 wherein two continuous miners are operated in the set of entries.

11. A method as set forth in claim 1 further comprising installing stoppings in the crosscuts to direct ventilation air to flow in two separate streams through the set of entries.

12. A method as set forth in claim 1 further comprising conveying the mined material out of the set of entries using a conveyor belt.