Roof bolt machine with quartz trapping device

Abstract

A roof bolt machine comprising a quartz trapping device adapted to connect with an exhaust stream of a dust system circuit of a roof bolt machine for reducing the amount of respirable dust and respirable quartz that is released into the environment from the exhaust stream. The quartz trapping device comprises, a container partially filled with a liquid, at least one inlet mounted on said container and adapted to connect the container with the dust system circuit of the roof bolt machine for directing the dust exhaust stream inside the container and a plurality of downward extending and upward extending baffles arranged in an alternating configuration. The baffles form together with the liquid a tortuous path through which the dust exhaust stream is conducted while it contacts the liquid, repeatedly, a number of times sufficient to cause a significant amount of the respirable dust and respirable quartz content of the dust exhaust stream to be captured inside the liquid and form a substantially clean exhaust stream, and an outlet mounted on said container for releasing the substantially clean exhaust stream.

Description

FIELD OF THE INVENTION

The present invention relates generally to roof bolt machines that are employed in coal mines to install roof bolts that support the roof of the mine. More particularly the present invention relates to a quartz trapping device that is adapted to operatively attach to an exhaust of a dust system circuit of a roof bolt machine to reduce or substantially eliminate the amount of respirable dust and respirable quartz dust that is released to the working environment. The invention also relates to an improved roof bolt machine comprising said quartz trapping device and a method for reducing or substantially eliminating emissions of respirable dust and respirable quartz dust into the working environment from the exhaust stream of roof bolt machines.

BACKGROUND OF THE INVENTION

When a mine tunnel is cut into the earth, the material forming the roof of the mine is relatively weak and will tend to collapse unless it is supported. The roof of a mine has been supported by drilling holes in the roof of the mine and inserting bolts into the holes. Typically, the upper end of each bolt is anchored in a hole and the bolt is tightened against a mine roof support plate to compress the material forming the mine roof.

Special machines known generally as roof bolt machines have been developed for assisting in the roof drilling and bolting process. Roof bolt machines are described, for instance, in U.S. Pat. Nos. 3,252,525; 3,337,880; 3,768,574; 3,842,610; 3,951,215; 4,050,259; 4,079,792; 4,290,490; 4,294,317; and 4,589,803 and which are incorporated herein by reference to the extent that is not inconsistent with the disclosure and claims of the present application. A typical roof bolt machine comprises a mobile chassis, including at least an operator's platform or a cab. A drilling assembly is mounted on the mobile chassis and includes a drillhead that has a drill bit that is operable to drill holes in a mine roof.

Large amounts of respirable dust and especially respirable quartz dust also known as respirable silica are released into the environment in coal mines through the dust exhaust stream of roof bolt machines, especially when the roof bolt machines are used to drill holes in a sandstone roof. The term "respirable" refers to very small size dust and quartz particles, which when present in the air, are inhaled by humans and are deposited in the lungs. Generally, respirable dust or quartz dust particles have an average size of less than about 5 microns. Overexposure to respirable quartz found in dust can cause scar tissue to form in the lungs, reducing the ability of the lungs to extract oxygen from the air we breathe, a disease known as silicosis. Silicosis is incurable but it can be prevented by implementing engineering controls in the work place that minimize the exposure of workers to respirable quartz dust. Because of the significant health risks associated with breathing respirable quartz dust found in the dust generated during drilling operations, mine operators take measures to reduce dust emissions into the working environment. For instance existing roof bolt machines employ a dust system circuit that includes a vacuum source, such as a blower, that creates a vacuum which is applied through connecting hoses to the drillhead unit of the roof bolt machine. The vacuum draws the drill cuttings and dust that are generated during drilling operation into a dust collection system before releasing the dust exhaust stream from the outlet of the vacuum source into the working environment. Existing dust collection systems employed by roof bolt machines are generally expensive, cumbersome, ineffective in removing very small size quartz particles, difficult to maintain and often times clog and result in a loss of production. Existing dust collection systems typically require that filters capable of trapping very fine particles, e.g., less than 15 microns in size, be used to remove the respirable size dust and quartz dust. These filters are expensive, not always very effective in capturing the very small size respirable dust, require regular maintenance and tend to clog rather easily, thus disrupting operations.

Therefore, there exists a need for an improved roof bolt machine that has a quartz trapping device that is economical, easy to maintain and effective in reducing the amount of respirable dust, especially respirable quartz dust, that is released into the environment during drilling operations.

SUMMARY OF THE INVENTION

The present invention provides an improved roof bolt machine that includes a quartz trapping device that is economical, easy to maintain and effective in reducing the amount of respirable dust, and respirable quartz dust, that is released into the environment.

In its broadest aspects the quartz trapping device of the present invention, which is also referred to as a quartz trapping apparatus or a quartz zapper, comprises a container partially or at least partially filled with a liquid. The container includes a top plate, a bottom plate and side plates. The container comprises at least one inlet that is adapted to be operatively attached to the dust system circuit of a roof bolt machine for introducing the dust exhaust stream from the roof bolt machine, particularly from a dust system circuit of the roof bolt machine, that contains respirable dust and respirable quartz dust inside (or into) the container. The container comprises a plurality of baffles, extending downward from the top plate, and a plurality of baffles extending upward from the bottom plate. The downward and upward extending baffles are arranged in an alternating configuration. The baffles, together with the liquid, form a tortuous path through which the dust exhaust stream is conducted in order to contact the liquid, to cause the respirable dust and respirable quartz dust to be captured by the quartz trapping device, and particularly by the liquid, and form a substantially clean exhaust stream leaving the quartz trapping device. The dust exhaust stream is contacted with the liquid inside the quartz trapping device repeatedly a number of times sufficient to remove at least a significant amount and preferably substantially all of the respirable dust and respirable quartz dust found in the dust exhaust stream. The container further includes an outlet for releasing the substantially clean exhaust stream into the environment.

The quartz trapping device may be used in conjunction with any dust collection devices or systems employed in roof bolt machines.

One embodiment of the present invention is directed to a roof bolt machine comprising a mobile chassis, at least one operator cab operatively connected to the mobile chassis, at least one drilling assembly mounted on the mobile chassis and operatively connected with said mobile chassis mounted on the drillhead. The drilling assembly comprises a drillhead including a drill bit. A motor is mounted on the mobile chassis, and is operatively connected to the drillhead for turning the drill bit. The roof bolt machine further comprises a dust system circuit comprising a vacuum source, a dust collection device (also referred to herein as a "dust collection system"), and at least one connecting hose for operatively connecting the drill bit with the vacuum source and the dust collection device, for applying a vacuum to the drill bit sufficient to draw drill cuttings and dust generated during the operation of the drill bit through the dust collection device. The roof bolt machine of the present invention further comprises a quartz trapping device which is preferably mounted downstream of the vacuum source of the dust system circuit or downstream of a muffler, which may also be included in the dust system circuit, downstream of the vacuum source.

The present invention further relates to a method for reducing respirable dust and respirable quartz dust, from the exhaust of a roof bolt machine, particularly from a dust system circuit of a roof bolt machine. The method comprises, introducing the exhaust stream from the dust system circuit into the quartz trapping device of the invention, directing the exhaust stream through the tortuous path formed by the plurality of baffles of the quartz trapping device to contact the liquid under conditions effective to remove a substantial amount of respirable dust and respirable quartz from the exhaust stream to form a substantially clean exhaust stream which is substantially free of respirable dust and respirable quartz and releasing the substantially clean exhaust stream through an outlet. The quartz trapping device is preferably placed downstream of the vacuum source of the roof bolt machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of the quartz trapping device.

FIG. 2 is a top view of an embodiment of the quartz trapping device.

FIG. 3A is a right side view of an embodiment of the quartz trapping device.

FIG. 3B is a left side view of an embodiment of the quartz trapping device.

FIG. 4 is a simplified schematic of one embodiment of an improved roof bolt machine, including a dust collection system, and the quartz trapping device of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Some of the terms used herein are defined as follows.

In the discussion of performance of the quartz trapping device, the recitation of removing "substantially all of the respirable dust and respirable quartz found in the dust exhaust stream" means that at least about 60 percent by weight, preferably about 60 percent by weight to about 90 percent by weight of the respirable dust and respirable quartz in the exhaust gas entering the quartz trapping device is removed therein.

The term "substantially clean exhaust stream" means an exhaust stream that results in an average concentration of respirable dust in the mine atmosphere of about 2 miligrams per cubic meter of air or less, preferably about 1 miligram per cubic meter of air or less, provided that the amount of respirable quartz in the respirable dust is less than about 10%, preferably less than about 7% and more preferably less than about 5% by weight, as measured according to the Mine Safety Health Administration's (MSHA) respirable dust measuring procedures. (See Coal Mine Sample Processing, Informational Report No. 1249, by Lewis D. Raymond, May 1998, incorporated herein by reference to the extent it is not inconsistent with the disclosure and claims of this application).

The Quartz Trapping Device

The quartz trapping device is described hereinafter by way of example in reference to an embodiment thereof shown in the accompanying FIGS. 1-3. However, it should be understood that the scope of the invention is not limited to the exact details of this example and many variations can be easily envisioned by those skilled in this art without departing from the scope of this invention as defined in the appended claims.

Referring to FIGS. 1-3, a quartz trapping device apparatus is provided which comprises a container 20 having at least one inlet 40 for receiving the dust exhaust stream and an outlet 46 for releasing the treated, substantially clean exhaust stream into the environment. When in operation the container 20 is at least partially filled with a liquid 30. The liquid is preferably water but any kind of non-flammable liquids can also be used. Preferably a water solution of a detergent, such as a soap is used. In one particularly preferred embodiment, a water solution is used that contains a soap identified as a coal treating substance such as DT-5 Coal Treating Compound, available from Breien Products, Zinkan Enterprises, located in Twinsburg, Ohio, in an amount of from about 0.01 to about 30 percent by weight, preferably from about 0.1 to about 10 percent by weight. Other coal treating substances or soap substances can be also be used as additives in the water. Examples of other non-flammable liquids that can be used include mineral oils, emulsions of oil and water. An example of a mineral oil that can be used is ISO™46 made by Chevron Products located at 555 Market Street, San Francisco, Calif., 94106. Emulsions of oil and water are available from Century Lubricants, Located in Huntington, W.Va.

The inlet or inlets 40 of the container are adapted to operatively connect the container 20 with the dust system circuit of a roof bolt machine for directing the dust exhaust stream inside the container 20. In the embodiment of FIGS. 1-3, the container 20 has two inlets 40 that are equipped with pipes 50 that are attached, preferably welded, at one end to each inlet 40. A nipple connector 60 is attached to the other end of each pipe 50 using a reducer piece 70. Flexible hoses or pipes 90 are secured by hose clamps 80 onto the nipple connectors 60 at one end and at the other end to the exhaust outlets of the mufflers of a roof bolt machine (not shown).

Connecting the quartz trapping device to the muffler outlets of existing roof bolt machines is the simplest and most economical means for retrofitting existing roof bolt machines with the present invention quartz trapping device. It should be understood however, that the quartz trapping device can be easily adapted to connect at any point of a dust system circuit of existing roof bolt machines, preferably downstream of the vacuum source of a dust circuit system.

Preferably the dust system circuit comprises a dust collection device which removes at least 50%, and more preferably at least 75%, of the dust entering the dust collection device. When the roof bolt machine is in operation, the exhaust is directed from the mufflers (or from the vacuum source) of the roof bolt machine through the hoses 90 and pipes 50 into the container 20. Pipe 50 has an inside diameter of from about 0.5 to about 4.0 inches, preferably of from about 1.0 to about 2.0 inches, more preferably of from about 1.5 to about 2.0 inches. Pipe 50 is preferably an L-shaped, double wall pipe having an inside diameter of 2.0 inches. The hose 90 has an inside diameter of from about 0.5 to about 4.0 inches, preferably from about 1.0 to about 2.0 inches, more preferably from about 1.5 to about 2.0 inches, and most preferably 2.0 inches.

The container 20 is equipped with a plurality of downward extending and upward extending baffles 100 and 110, respectively. Downward extending baffles 100 are attached to the top plate 22 of the container 20, and extend downward toward the surface 32 of the liquid 30. The baffles 100 are preferably welded in place to the top plate 22. The downward extending baffles 100 are preferably not immersed in the liquid 30. The distance between the low edge 102 of each downward extending baffle and the liquid surface 32 may range from about 0.5 to about 4 inches, preferably from about 1.0 to about 4.0 inches, more preferably from about 1.5 to about 2.0 inches, and most preferably 2.0 inches.

Upward extending baffles 110 are attached, preferably welded, to the bottom plate 24 and extend upward toward the top plate 22. The upward extending baffles 110 are partially immersed in liquid 30 and their upper edge 112 emerges out of the liquid 30 and extends to a distance of about 0.5 to about 4 inches, preferably about 1.0 to about 4 inches, more preferably about 1.5 to about 2.0 inches above the liquid surface.

The baffles 100 and 110 are arranged inside the container 20 in a plurality of pairs comprising adjoining baffles, each pair comprising a first downward extending baffle and a second upward extending baffle. The baffles in each pair overlap, i.e. the upper edge 112 of the upward extending baffles 110 is generally higher than the low edge 102 of the downward extending baffles 100. As a result, the exhaust stream has to follow a tortuous path formed between the downward extending and upward extending baffles and the liquid surface 32 as shown by the arrows in FIG. 1. Preferably, the baffles in each pair are spaced apart at a distance that is shorter than the distance between the consecutive pairs, i.e. between the second upward extending baffle of each pair of baffles and the first downward extending baffle of the next pair of baffles. The distance between the baffles in each pair may range from about 1.0 to about 6 inches, preferably from about 3 to about 5 inches, and more preferably from about 2 to about 3 inches. The distance between two consecutive pairs of baffles may range from about 1 to about 10 inches, preferably from about 2 to about 5 inches and more preferably from about 3 to about 4 inches.

The quartz trapping device is preferably equipped with a terminal baffle 120 extending downward from top plate 22 in front of the outlet 46, preferably forming an angle with top plate 22 of from about 10 to about 60 degrees, more preferably from about 20 to about 40 degrees.

When in operation, the dust exhaust stream from the roof bolt machine (e.g., from a muffler or the vacuum source) is directed inside the container 20 through inlets 40 and it contacts liquid 30. Preferably, the dust exhaust stream enters the container 20 at a generally vertical orientation in relation to the liquid surface 32. At least some of the dust exhaust stream, when it enters the container 20, is forced by the first downward extending baffle to impinge at a relatively high velocity on the liquid surface 32 where it is deflected and redirected toward the first upward extending baffle. The first pair of baffles in combination with the liquid 32 forces the dust exhaust stream upward away from the liquid through the passage formed between the baffles of the first pair. The next downward extending baffle forces at least some of the dust exhaust stream downward toward the liquid surface 32 where it is once again deflected away from the liquid 30 and towards the second passage formed between the second set of baffles. Without wishing to limit the scope of the present invention in any way, it is postulated that the force of the dust exhaust stream as it moves between the baffles creates a turbulence in the liquid which causes the respirable dust and respirable quartz to be captured by the liquid. This method of contacting the dust exhaust stream with the liquid 32 inside the quartz trapping device is repeated a number of times, which is believed to be sufficient to cause a significant amount of the respirable dust and respirable quartz present in the dust exhaust stream to be captured by the quartz trapping device, and particularly by the liquid. The quartz trapping device may remove at least about 60 percent by weight, preferably from about 60 percent by weight to about 90 percent by weight, more preferably from about 90 percent by weight to about 99 percent by weight, and most preferably more than about 99.9 percent by weight of the respirable dust and respirable quartz dust entering the quartz trapping device. Thus, the exhaust stream exiting the quartz trapping device is substantially free of respirable dust and respirable quartz dust.

Preferably, the upward extending baffles 110 have slots 114 cut in them to allow the liquid level to be easily maintained without having to fill each compartment to the appropriate level separately. The quartz trapping device is partially filled with liquid 30 through an opening 34 which is positioned preferably at the top plate 22 of the container 20. A cover plate 36 seals the opening when the quartz trapping device is in operation. The quartz trapping device is equipped with means for checking the level of liquid 32 in the container 20. For instance a pipe plug 42 may be installed at the side of the container to indicate the desired level of liquid in the container. Another pipe plug 44 is located at the bottom plate or on one of the side plates near the bottom plate to allow the liquid to be drained.

The system requires little or no maintenance other than filling the container with liquid and emptying the respirable dust and respirable quartz containing liquid from the container periodically.

The quartz trapping device can be easily attached to the muffler outlets or at any point after the vacuum source of the dust system circuit of existing roof bolt machines. In one embodiment, the quartz trapping device is equipped with a means for securely attaching the quartz trapping device to the roof bolt machine. In the embodiment shown in FIGS. 1-3 the quartz trapping device is equipped with four mounting brackets 52 which are generally positioned near the four corners of the bottom plate 24 of the container 20. Each bracket 52 has a threaded opening 54 for receiving a bolt (not shown). The brackets may be used to attach the quartz trapping device to a muffler of a roof bolt machine.

The dimensions of the quartz trapping device roof bolt machine may vary significantly to accommodate the dust load and volume of gases generated by different size roof bolt machines. Preferably, the quartz trapping device is designed to allow a residence time for the incoming dust exhaust stream i.e., the ratio of the volume of the quartz trapping device container that is free of liquid to the volumetric rate of the dust exhaust stream, from about 0.1 to about 60 seconds, more preferably from about 0.5 to about 30 seconds, and more preferably from about 1 second to about 10 seconds.

Roof Bolt Machines

The present invention is also directed to a roof bolt machine which includes a quartz trapping device of this invention. Except for the presence of the quartz trapping device, the roof bolt machine has the construction and is operated substantially in the manner of previously-known roof bolt machines, described herein and known in the art. It should be understood however that the quartz trapping device of the present invention can be easily adapted to be attached to any type of roof bolt machine. Thus, in summary a roof bolt machine comprises a mobile chassis which is supported on wheels, preferably four independently driven wheels. Preferably, the wheels are each hydraulically actuated and provide for the tramming of the chassis into the drilling and bolting position within a mine passageway. At least one operator cab is mounted to the front of the chassis. The cab has a floor or deck and preferably a protective canopy. Positioned in front of the operator cab is at least one drilling assembly comprising a drillhead having a drill bit. A motor mounted on the mobile chassis is operatively connected with the drillhead for turning the drill bit. The drilling assembly is provided with a means for positioning the drillhead up-and-down and side-to-side in relation to the operator cab. The drilling assembly, the drillhead and the means for positioning the drillhead are preferably actuated by hydraulic devices and are controlled by the operator through hydraulic operated controls.

A roof bolt machine of the present invention comprises a dust system circuit which includes a vacuum source, a dust collection device, and at least one connecting hose for operatively connecting the drill bit with the vacuum source and the dust collection device for applying a vacuum to the drill bit sufficient to draw the drill cuttings and dust generated during the operation of the drill through the dust collection device. The quartz trapping device is installed after the vacuum source or after the mufflers. Any dust collection device can be used in conjunction with the quartz trapping device and the invention is not limited to the specific embodiments described herein which are only discussed for the purpose of illustrating the invention. The vacuum source is any conventional device which can be used to produce sufficient vacuum in a roof bolt machine, such as a blower.

In one embodiment, shown in FIG. 4, the dust system circuit comprises a drillhead 200 which is used to rotate a hollow drill bit 210 which drills vertical holes in the mine roof, preparatory to the insertion of an anchored roof bolt. The hollow drill bit 210 receives the drill cuttings and dust which are drawn through the drillhead unit by a vacuum which is applied to the drillhead unit through a vacuum hose 220 by a vacuum source such as a blower 230, by way of a dust collection device or system 240 as shown in FIG. 4, preferably at a pressure of from about 5 to about 60 inches of mercury, more preferably from about 10 to about 40 inches of mercury, and most preferably from about 15 to about 20 inches of mercury. The blower 230 is preferably equipped with a relief valve (not shown) to prevent high vacuum. The dust exhaust stream from the outlet 250 of the blower 230 contains small size dust particles, especially respirable size dust particles which are difficult to remove with conventional methods, and it is directed into a quartz trapping device 10 through a muffler device 260 and a connecting hose 90. At least one muffler device (not shown in FIG. 4) for dampening the noise of the exhaust from the quartz trapping device may also be employed after the quartz trapping device.

The dust collection system 240 may comprise one or more of any dust collection devices.

In a preferred embodiment the dust collection system comprises a three stage system that is usually contained in a single housing; however, the third stage may be located in a separate housing. In the three stage system, dust enters the collector (or housing) through a hose on the side or back and is carried into a first stage cyclone. This cyclone removes over 95 percent of all incoming dust and water and deposits them in the main dust storage chamber.

Fine dust exits at the top of the first stage cyclone through an air chamber where it goes to the second stage separator. The second stage separator tubes are reverse flow mini cyclones which remove over 84 percent of the fine dust that enters the main dust storage chamber. Thus, less than 1 percent of total incoming dust passes out of the top of the second stage and through a hose to the final filter stage.

The third stage filter is a heavy-duty, pleated paper cartridge type element. Dust collected in this filter is extremely fine (less than 15 microns in size), yet is removed with an efficiency of over 99.9 percent. Clean air passes through the final filter to the exit manifold and outlet hose.

The roof bolt machine may also be equipped with a conventional auto-dump, pre-cleaner dust system designed to receive collected dust from the dust collection device and release the accumulated dust often to minimize the amount of dust the dust collection system must handle.

A roof bolt machine equipped with a three stage dust system and a pre-cleaner dust system is marketed by J. H. Fletcher & Co., Machine Model DDR-13, C-F and is described in the Service Manual for that machine.

In the embodiment of FIG. 4 the quartz trapping device is preferably adapted to be attached to the muffler outlets that are typically installed after the vacuum source of any roof bolt machine, as illustrated in FIG. 4. However, the quartz trapping device can also be installed at any point after the vacuum source. In one embodiment the quartz trapping device is placed after the vacuum source but before the mufflers.

In any embodiment of the invention, the quartz trapping device removes substantially all of the respirable dust and respirable quartz that enters it, so that a very small fraction of the respirable dust and respirable quartz dust entering passes out of the outlet of the quartz trapping device. The quartz trapping device captures the quartz content of the dust exhaust stream to form a substantially clean exhaust stream that is released into the environment. The quartz trapping device may be employed with all types of roof bolt machines equipped with a dust system circuit. A dust system circuit may typically include a drillhead, a dust collection system, a relief valve, a vacuum source, at least one muffler and connecting hoses of the roof bolt machine, but it should be understood that the present invention is not limited to such a system only. Details of roof bolt machines are known in the art and can be found for instance in U.S. Pat. No. 4,290,490 issued to Barthe et al. on Sep. 22, 1981 and U.S. Pat. No. 4,589,803 issued to Totten on May 20, 1986 both of which are incorporated herein by reference for all purposes to the extent that they are not inconsistent with the present invention as disclosed and claimed.

EXAMPLES

Example 1

This example describes one specific embodiment of the invention in conjunction with FIGS. 1-3. A quartz trapping device 10 is provided that is designed for optimum operation in combination with a dual roof bolt machine manufactured by the J. H. Fletcher & Co., Model Number DDR-13, C-F. The dimensions of the container 20 are 24 inches long, 14 inches high and 12 inches wide. The container 20 is made from metal about ⅛ inches thick. Mounted on the top plate 22 at the left corner are two double wall, L-shaped pipes 50 having an internal diameter of 2 inches that are welded to the inlets 40 of the container 20. A 1.5 inches nipple 60 is installed in each L-shaped pipe 50 by using 2×1.5 inches reducer. Hoses 90 are used to connect the quart trapping device to the muffler outlets of a roof bolt machine. The hoses have an internal diameter of about 1.5 inches and are secured to the nipple connectors 60 by 2 inch hose clamps 80. The container is filled with 5 inches of a water solution containing DT-5 Coal Treating Compound through a 4×5 inches opening 34 at the top plate 22. About 1 to 2 inches of a cylindrical bar having a diameter of about 3 inches of the DT-5 Coal Treating Compound is added to the water. The opening 34 is sealed with a cover plate 36 and a rubber gasket. The cover plate 36 is bolted on the top plate 22 using four ⅜ inches head bolts 38. A 0.5 inches pipe plug 42 is located on plate 28 about 5 inches from bottom plate 24. The pipe plug 42 can be removed to check the water level. The water can be drained by removing a 0.75 inches pipe plug located on plate 26 near the bottom plate 24 of the container 20. The system can be flushed and cleaned with a water hose by removing the top cover plate 36 and the drain plug 44.

Inside the quartz trapping device there are two pairs of baffles. The downward extending baffles 100, which are 7 inches long, extend from the inside top, down to within 2 inches from the surface of the water 32. The upward extending baffles 110, which are 8 inches long, extend from the inside of the bottom plate 24 to a distance of about 3.5 inches above the water surface 32. The distance between the baffles in each pair of baffles is about 1.5 inches and the distance between the two pairs of baffles is about 3.5 inches. An outlet or terminal baffle 120 is located in front of the outlet 46 of the container leaving a clearance of about 1 inch between the low edge 122 of the outlet baffle 120 and the side plate 26 of the container 20. An L-shaped pipe 47 is connected to the outlet 46. The upward extending baffles 110 have 0.5 inches slots 114 cut in them to allow the water level to be easily maintained substantially uniform along the entire length of the container 20.

Preferably the container 20 is equipped with a terminal baffle 120 that extends downward from top plate 22, in front of the outlet 46 forming an angle of about 45 degrees with the top plate 22.

The volumetric rate of the exhaust stream entering the quartz trapping device may vary by adjusting the vacuum of the vacuum source. Preferably the vacuum is set at a pressure of about 15 inches of mercury which results in a volumetric rate of about 120 cubic feet per minute of the exhaust stream entering the quartz trapping device 10 through both inlets 40 of the container 20. At this volumetric rate from about 0.25 inches to about 1.5 inches of respirable dust and respirable quartz accumulate in the device in a period of about six days.

The present invention is not limited to the aforementioned embodiments. Many variations of the present invention can be easily envisioned by those skilled in this art without departing from the scope of this invention as defined in the following claims.

Claims

1. A quartz trapping device for use with a roof bolt machine, the quartz trapping device comprising:

a container comprising a top plate, a bottom plate and side plates wherein said container is at least partially filled with a liquid;

at least one inlet mounted on said container adapted to be operatively connected with and receive an exhaust stream from a drill bit of the roof bolt machine;

a plurality of downward extending baffles attached to the inside of the top plate and extending downward from the top plate toward the liquid surface;

a plurality of upward extending baffles attached to the inside of the bottom plate and extending upward from the bottom plate toward the top plate;

wherein said downward and upward extending baffles are arranged in an alternating configuration defining a tortuous pathway for the exhaust stream, causing the exhaust stream to deposit substantially all of the respirable dust and respirable quartz entrained therein in the liquid; and

an outlet mounted on said container for releasing a substantially clean exhaust stream.

2. The quartz trapping device of claim 1 wherein said plurality of downward and upward extending baffles are arranged in a plurality of pairs, each pair comprising a first downward extending baffle and a second upward extending baffle, wherein said first downward extending and said second upward extending baffles overlap and are spaced apart a shorter distance than the distance between the second upward extending baffle of a first pair of baffles and a first downward extending baffle of the next pair of baffles.

3. The quartz trapping device of claim 1 wherein the downward extending baffles extend to a distance of about 0.5 to about 4.0 inches above the liquid surface and the upward extending baffles extend to a distance of about 0.5 inches to about 4.0 inches above the liquid surface.

4. The quartz trapping device of claim 2 wherein the distance between the first downward extending baffle and the second upward extending baffle in each pair of bafles is from about 1.0 to about 6.0 inches and the distance between the second upward extending baffle of a first pair of baffles and the first downward extending baffle of the next pair of baffles is from about 1 to about 10 inches.

5. The quartz trapping device of claim 1 further comprising a terminal baffle positioned in front of the outlet.

6. The quartz trapping device of claim 5 wherein said terminal baffle is inclined at about 20 to about 40 degrees relative to the top plate.

7. The quartz trapping device of claim 1 wherein said liquid is a non-flammable liquid.

8. The quartz trapping device of claim 1 wherein said liquid comprises at least one of water, a water solution including a detergent, a water solution including a coal treating substance, mineral oil, or an emulsion of water and oil.

9. The quartz trapping device of claim 1 wherein said container is made from metal or plastic.

10. The quartz trapping device of claim 1 wherein the upward extending baffles include slots.

11. The quartz trapping device of claim 1 wherein said liquid comprises water.

12. A quartz trapping device for reducing the amount of respirable dust and respirable quartz released into the environment from a dust exhaust stream of a roof bolt machine, said quartz trapping device comprising:

a container at least partially filled with a liquid;

at least one inlet mounted in said container adapted to be operatively connected with and receive the dust exhaust stream from the roof bolt machine into the container;

a plurality of upward extending and downward extending baffles attached to a bottom plate and a top plate of the container, respectively, wherein said baffles form together with the liquid a path through which the dust exhaust stream is conducted in order to cause the respirable dust and respirable quartz in the dust exhaust stream from the roof bolt machine to be captured inside the liquid, and form a substantially clean exhaust stream;

an outlet mounted on said container for releasing the substantially clean exhaust stream.

13. A roof bolt machine comprising:

a mobile chassis;

at least one operator cab operatively connected to said mobile chassis;

at least one drilling assembly mounted on said mobile chassis and operatively connected with said mobile chassis, said drilling assembly comprising a drillhead including a drill bit;

a motor mounted on said mobile chassis, operatively connected to said drillhead for turning the drill bit mounted on said drillhead;

a dust system circuit comprising a vacuum source and a dust collection device and at least one connecting hose for operatively connecting the drill bit with the vacuum source, and the dust collection device for applying a vacuum to the drill bit sufficient to draw the drill cuttings and dust generated during the operation of the drill bit through the dust collection device; and

a quartz trapping device, operatively associated with the dust system circuit, which removes quartz and dust from the dust collection circuit.

14. The roof bolt machine of claim 13 wherein the drill bit is a hollow drill bit so that the vacuum applied by the vacuum source and the connecting hose draws the drill cuttings and the dust through the hollow drill bit, and through the connecting hose.

15. The roof bolt machine of claim 13 wherein said dust system circuit further comprises at least one muffler attached to the outlet of said vacuum source for dampening the noise of the dust exhaust stream exiting the vacuum source and said quartz trapping device is connected to said at least one muffler.

16. The roof bolt machine of claim 13 wherein said dust collection device comprises a three-stage dust collection system comprising:

a first stage cyclone, a second stage separator comprising reverse flow mini cyclones, a third stage filter, and a main dust storage chamber.

17. The roof bolt machine of claim 13 wherein said quartz trapping device comprises:

a container comprising a top plate, a bottom plate and side plates wherein said container is at least partially filled with a liquid;

at least one inlet mounted on said container and adapted to connect the container with an exhaust of a dust system circuit of a roof bolt machine for directing a dust exhaust stream from the dust system circuit into the container;

a plurality of downward extending baffles attached to the inside of the top plate and extending downward from the top plate toward the liquid surface;

a plurality of upward extending baffles attached to the inside of the bottom plate and extending upward from the bottom plate toward the top plate;

wherein said downward and upward extending baffles are arranged in an alternating configuration; and

an outlet mounted on said container for releasing an exhaust stream.

18. The roof bolt machine of claim 17 wherein said upward extending baffles include slots.

19. The roof bolt machine of claim 18 wherein said plurality of downward and upward extending baffles are arranged in a plurality of pairs, each pair comprising a first downward extending baffle and a second upward extending baffle, wherein said first downward extending and said second upward extending baffles overlap and are spaced apart a shorter distance than the distance between the second upward extending baffle of a first pair of baffles and a first downward extending baffle of the next pair of baffles.

20. The roof bolt machine of claim 17 wherein the downward extending baffles extend to a distance of about 0.5 inches to about 4.0 inches from the liquid surface and the upward extending baffles extend to a distance of about 0.5 inches to about 4.0 inches above the liquid surface.

21. The roof bolt machine of claim 19 wherein the distance between the first downward extending baffle and the second upward extending baffle in each pair of baffles is from about 1.0 to about 6.0 inches and the distance between the second upward extending baffle of a first pair of baffles and a first downward extending baffle of the next pair of baffles is from about 1 to about 10 inches.

22. The roof bolt machine of claim 17 wherein the quartz trapping device further comprises a terminal baffle positioned in front of the outlet wherein the terminal baffle is inclined at about 20 to about 40 degrees relative to the top plate.

23. The roof bolt machine of claim 17 wherein said liquid is a non-flammable liquid.

24. The roof bolt machine of claim 17 wherein said liquid comprises at least one of water, a water solution including a detergent, a water solution including a coal treating substance, mineral oil, or an emulsion of water and oil.

25. The roof bolt machine of claim 17 wherein said container is made from metal or plastic.

26. The roof bolt machine of claim 17 wherein said liquid comprises water.

27. A method for reducing respirable dust and respirable quartz dust emissions from a dust exhaust stream of a roof bolt machine, the method comprising the steps of:

providing a quartz trapping device comprising:

a closed container comprising a top plate, a bottom plate and side plates;

a liquid at least partially filling the container;

at least one inlet mounted on said container and adapted to connect the container with a dust system circuit of a roof bolt machine;

a plurality of downward extending baffles attached to the inside of the top plate and extending downward from the top plate toward the liquid surface;

a plurality of upward extending baffles attached to the inside of the bottom plate and extending upward from the bottom plate toward the top plate;

wherein said downward and upward extending baffles are arranged in a generally alternating configuration; and

at least one outlet mounted on said container;

passing a stream of air in which is entrained respirable dust and respirable quartz from the dust collection circuit of a roof bolt machine into the at least one inlet of the quartz trapping device; and

removing from the at least one outlet a stream of air which is substantially free of respirable quartz and dust.

28. A method for preventing respirable quartz from entering the environment of an underground mine, the method comprising the steps of:

a) drilling into rock in the underground mine with a drill bit;

b) using suction to remove the dust generated by the drilling from around the drill bit into a stream of air, the air then having an unhealthful amount of respirable quartz dust entrained therein;

c) passing the stream of air with the quartz dust entrained therein into a closed container;

d) passing the stream of air with the dust past a series of baffles in the closed container, the series of baffles defining a tortuous path for the air, the air impinging multiple times upon the surface of a liquid which partially fills the closed container to produce a substantially clean exhaust stream;

e) passing the substantially clean exhaust stream out of the closed container and into the environment of the underground mine.

29. The method of claim 28 wherein the liquid in the closed container comprises at least one of water, a water solution including a detergent, a water solution including a coal treating substance, mineral oil, or an emulsion of water and oil.

30. The method of claim 28 wherein after step b) and before step c) the method further comprises the step of:

b1) passing the stream of air with the quartz dust entrained therein into a first dust removal device comprising a cyclone.

31. The method of claim 30 wherein the first dust removal device further comprises a filter.

32. The method of claim 28 wherein the volumetric flow rate of the stream of air with the quartz dust entrained therein is at least 120 cubic feet per minute, and the stream of air is forced through at least one constriction formed by a baffle, the closed container, and the liquid, wherein the constriction is less than two inches in height.