Mining system

Details Mining system Mining system

2002-06-26

2004-09-28

Kreck, John (Department: 3673)

Mining or in situ disintegration of hard material

Processes

C299S019000, C299S011000, C299S095000

Reexamination Certificate

active

06796616

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates, in general, to a mining system for extracting mineral deposits, and more specifically, but without limitation, to a mining system utilizing a combination of surface contour mining and underground shortwall or longwall mining systems.
BACKGROUND OF THE INVENTION
Conventional surface mining systems have devastating environmental results. In hilly or mountainous regions, surface contour mining is accomplished by removing timber and clearing the area to be mined, making a strip cut to form a substantially horizontal bench and a vertical highwall that exposes the seam of mineral deposits to be removed. Another technique is to simply remove the entire top portion of the mountain to extract the minerals deposited below.
Underground mining systems are less damaging to the environment, but more costly and inefficient with lower production rates. When underground mining systems are used to extract mineral or coal deposits from a mineral or coal reserve
10
, the reserve
10
is divided into panels
12
as shown in
FIG. 1
which are laid out and developed for both shortwall mining and longwall mining operations. Coal reserves conducive to mining adjacent parallel panels (Panels
1
to
8
as shown in
FIG. 1
) are most desirable because they facilitate panel development and allow shorter equipment moves. As can be seen, the panels
12
are generally rectangular in shape having gate entries
14
(a headgate and tailgate) extending along each length, and are all connected at one end by main entries
16
. In modern mining systems, these panels
12
are developed using continuous miner units. In modern longwall mining systems, panels typically range from 400 to 1200 feet in width and from 4,000 to 15,000 feet in length. In modern shortwall mining systems, the shortwall panels typically range from 100 to 200 feet in width and from 2,000 to 4,000 feet in length. Production of coal or other sedimentary deposits begins at one end of the panel
12
, the starter entry
18
, to mine the seam along its face or wall in the direction indicated by the arrow
19
.
Referring more specifically to
FIG. 2
, panel
1
of
FIG. 1
is shown in more detail as panel
20
having headgate entries
22
a-c
, collectively the headgate
22
, and the tailgate entries
24
a-c
, collectively the tailgate
24
, referred to above. While the direction of mining proceeds in the direction indicated by the arrow
19
, production or plowing of the coal always proceeds from the headgate
22
to the tailgate
24
in the direction shown by the arrow
25
for both longwall and shortwall mining systems as will be described below in more detail. A “three-entry” development system utilizes the three maingate entries
16
a-c
, collectively the maingate
16
, the three headgate entries
22
a-c
, and the three tailgate entries
24
a-c
that are commonly used to provide the necessary airways and escapeways and other functions. The system permits installation of belt and track in the center entry, and allows one outer entry to be used as a return airway. This system is complex and expensive to develop, and is well-known in the mining business.
Upon completing development of the panels
12
, the longwall or shortwall mining of the panel
20
commences as shown in
FIGS. 3 and 4
, respectively. Referring more specifically to
FIG. 3
, longwall machinery
30
and miners are protected by roof supports
32
,
33
designed to withstand tremendous overburden pressures. The material containing the minerals is cut from the face of the seam by a plough or shearer
34
of the longwall machinery
30
and drops onto an armored chain conveyor system (not shown) for transport to a main conveyor system
36
, which in turn transports the material to the surface. As successive cuts are made along the face of the seam from the headgate
22
to the tailgate
24
in the direction of production indicated by the arrow
25
, the roof supports
32
,
33
and armored chain conveyor are advanced into the seam in the direction of mining indicated by the arrow
19
, allowing the overburden to collapse or cave-in behind the roof supports
32
,
33
to form what is known as a gob
38
of loosely-packed material. The roof supports
32
,
33
not only advance in the mining direction, but also are extendable as known in the art with the supports
32
being shown in the extended configuration and the supports
33
being shown in the retracted configuration.
Referring more specifically to
FIG. 4
, shortwall machinery
40
and miners are also protected by roof supports
42
,
43
designed to withstand tremendous overburden pressures. Unlike the longwall miner which ploughs the seam parallel to its face, a shortwall miner cutting head
44
of the shortwall machinery
40
which is approximately 10 to 12 feet in width plows in a direction generally perpendicular to the face of the seam and drops the material onto an armored chain conveyor system (not shown) for transport to a main conveyor systems
46
, which in turn transports the material to the surface. As successive cuts are made along the face of the seam from the headgate
22
to the tailgate
24
in the direction of production indicated by the arrow
25
, the roof supports
42
,
43
and armored chain conveyor are advanced into the seam in the direction of mining indicated by the arrow
19
, allowing the overburden to collapse or cave behind the roof supports
42
,
43
forming the gob
48
. The roof supports not only advance in the mining direction as shown by supports
42
a
and
42
b
, but also are extendable as known in the art with supports
42
being shown in the extended configuration and supports
43
being shown in the retracted configuration. The shortwall mining system requires significantly less capital and is more flexible in handling geological conditions that vary through the mineral reserve. The only significant disadvantage of the shortwall mining system is that the production rate is somewhat lower as compared to the longwall mining system.
It should be apparent from the above, the primary problem associated with underground longwall and shortwall mining systems is the cost and time associated with developing and creating the panels, and then moving either system from panel to panel underground to mine the entire mineral reserve
10
. The moves from panel to panel result in many days of downtime at a high cost to the mining operation. The ingress and egress entries and ventilation associated with the system are all expensive. Time travel to the seam face for the miners is also a significant cost associated with these systems.
Moreover, federal legislation (e.g., Clean Water Act) restricts the use of waste rock produced by large scale surface mining systems as “fill material” legitimately disposed of at other locations. Recent court decisions have held that excess spoil generated by mining operations is waste that does not qualify as fill material that can disposed of as valley fills. Thus, the disposal of excess spoil is a significant problem.
SUMMARY OF THE INVENTION
Apparatus and method for extracting mineral deposits is provided by combining surface contour mining with underground longwall or shortwall mining techniques. More specifically, such apparatus and method uses surface contour mining to create a staging bench and highwall for inserting either shortwall or longwall mining equipment into the seam of a mineral reserve to commence a continuous mining operation without the need for developing separate underground panels. The highwall formed at the point of insertion, the insertion highwall, extends between opposing highwalls formed on either side of the insertion highwall and generally in parallel to the direction of production and perpendicular to the direction of mining. A continuous miner is used to develop a starter entry cut into the seam extending along the entire length of the insertion highwall. Roof supports are advanced into the starter entry cut as formed by the continuous miner across the insertion highwall, and are then covered with

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