Steeply Inclined Seam Longwall Coal Mining Projects

Steeply Inclined Seam Longwall Mining Projects

Ground commissioning of longwall shearer for steeply inclined working face

According to the angle size, Chinese coal industry could be divided into the following stype: nearly-horizontal coal seam if the dip angle <12°, gentally-inclined coal seam if the dip angle is between 12°~25°, inclined coal seam if the dip angle is between 25°~45°, steeply-inclined coal seam if the dip angle >45°(among which if the dip angle is between 35°~55°, it's called large inclination coal seam). Large inclination coal seam and steeply-inclined coal seam are widely scattered in many coal mines in China, which takes about 21% among the explored reserve, and many of the coal seams are scarce and protectively-developed coal resources. The large inclination coal seams are complicated and hard to exploit coal seam recognized all over the world. Improving the standard of safety assurance and recovery rate is the most important strategical issue for Chinese coal resources and energy.
 

Large Dip Angle Fully Mechanized Coal Mining Project
3.1 General Situation of Working Face

Chart 1 The Position of Working Face and Relationship between Ground and Underground

Parameters of working face & Conditions of coal seam

Relative Position of Ground	The ground corresponding to working face is from Thatch Hill to Tea Taipa. The ground is slope topography, southeast is high and northwest is low. There is no building and water, the ground surface is covered by bamboo forest, natural grassland and firs.
The Influence of Mining On the Ground Facilities	There is two Northwest trending subsidiary fold because the working face is squeezed by the Northeast. This will affect layout and mining of working face directly.
Underground Location and Adjacent Relations	This working face is a monocline, it is located the West Wing of the Daluowan Anticline 561 mining area. There is a small fold which is skew with the mechanical roadway of working face. East of the working face is 5634 goaf of working face. South of the working face is 5614 goaf of working face. North is 5654 working face, its mining is coming to an end, following is 321 mining area. Southeast of the working face across the 528 main adit, and there is security coal pillar 50m.
Length of Strike (m)	700	Length of Incline (m)	78~160	Area(m2)	74873.72

Parameters of working face: the length of coal seam strike is 700m, the length of inclined is about 88-160m, dip angle of coal seam is 0°- 49°, average dip angle is 34°, inclined area is 74873.72m2.


Figure 3.1.1 Fully Mechanized Working Face and Roadway Layout


Geological Structure

This working face is a monocline, it is located the West Wing of the Daluowan Anticline 561 mining area. There is a oblique working face formed by anticline and syncline of two axial N31 ~ E because the working face is affected by the tectonic stress of N59°W. Ventilating roadway of working face is less affected by the fold, dip angle is between 36°~38°, the affected part is the north of ventilating roadway. Mechanical roadway is affected greatly by the fold, the dip angle varies between 0°~49°. Geological profile of working face is shown in Figure 1.1.

Figure 3.1.2 Geological Profile of Working Face

The working face mainly formed by reverse fault (number 01, 03, 11) of N50°W inclination because of the effect of fold, the throw is 0.7m~3.5m, it is in parallel with the fold. Specific location is: 5616-01# strike reverse fault, H=0.7m, 27.8m away from the south of mechanical roadway 61872 point; 5616-03# strike reverse fault, H=3.5m, 16m away from the south of mechanical roadway 61878 point; 5616-11# strike reverse fault, H=1.1m, located 3# exploration entry 61877 point of working face. Ventilating roadway developed fault without the effect of fold, there is a strike reverse fault at the point of ventilating roadway 61770, H=0.90m.
 Chart 2 Geological Conditions

Number of Fault	Property of Fault	Fault Occurrence (°)∠(°)	Fault Throw(m)
F561601	Reverse Fault	310°∠65°	0.7
F561603	Reverse Fault	310°∠60~70°	3.5
F561605	Reverse Fault	125°∠05°	3.0
F561607	Reverse Fault	125°∠10°	1.1
F561609	Reverse Fault	135°∠20°	2.5~3.0
F561611	Reverse Fault	333°∠78°	1.1
F561602	Reverse Fault	12°∠50°	0.9
F561604	Reverse Fault	226°∠18°	1.5
F561606	Reverse Fault	312°∠15°	2.5
F561608	Reverse Fault	312°∠15°	1.8~2.5

Roof and Floor of Coal Seam
The false roof of coal seam is a layer of clay stone, the thickness is about 0.2m, and immediate roof is carbonaceous mudstone, the thickness is about 8m. The main roof is carbonaceous mudstone and sandstone. There is a thin layer of limestone containing flint above the main roof, commonly known as "small iron plate" which is the marker bed. Direct floor is carbonaceous mudstone, and the thickness is about 0.7m. The hard floor is mudstone, sandstone and shale, the thickness is 1.0m ~ 12.2m, average number is 6.60m. Under the hard floor is bauxite and fracture bauxite rock. We can see from the data that the roof is relatively complete, but there are some small faults and fracture. The roof of coal seam belongs to class two.
3.2 Equipment selection
Because of the geological structure of the 260m section of the working face approaching to the open-off cut is very complicated. Strike of the upper segment of the working face 90m to more than 200m, meanwhile, when construction of the roadway , strike of the conveyor roadway from the negative slope 7°suddenly become positive slope 12°, dip direction is also from -10°become the positive slope gradually to 39°, Dip of the working face is basically normal and becomes more uniform at 40°; Coal Seam of the working face with dirt band 2 to 4 layer, is a complex structure of coal seam, coal thickness 0.6m~3.18m, most stable at around 2.5m.
Combined with the existing level of technology, the research group decided to adopt the steeply inclined fully-mechanized mining technology for mining, on the first after alignment of upper segment and lower segment, connected together and then integrated propulsion, working face equipment according to characteristic working face of the steeply inclined make the following requirements:
(1) Coal shearer
Fully Mechanized Coal Mining Face in Steeply Dipping used of coal shearer as chainless haulage, using of coal shearer large inclination angle fully mechanized mining face the chainless traction, use shearer traction driving gear box and travel gear box with rows of pins and mounted on a conveyor engaging, on the other side on ramp plate of conveyor by coal wall side use roller to keep machine balance, coal shearer set with hydraulic brake system, In the case of ensuring the failure of a brake, it can also meet the operation and braking of the coal shearer, not because of a brake and coal shearer appeared to down.
It uses cutting coal downlink, uplink collect floating coal, mainly considering the traction shearer and down of shearer whether can be controlled, With the accumulation of mining experience, at present, the large dip and working face of steeply inclined fully-mechanized mining technology, cutting coal downlink are feasible, a disadvantage is that the uplink cutting coal easy appear channeling gangue. After frame the front door of gangue, problem of channeling gangue is solved.
(2)Conveyor
Scraper conveyor is the key to ensure the stable operation of coal shearer. The conveyor is controlled by the hydraulic support of the working face and the rigid connection of the conveyor, support has a large capacity to limit down of the conveyor. Support must ensure that not to fall, the conveyor will not fall.
(3) Hydraulic support
Hydraulic chock-shield support is used in the working face, which absorbs the advantages of the shield support, and can be used for the working face of 60°, which increased a walkway and field operating space.

In order to prevent support working face dumping to the lower side of working face, the first, manage the end support, not to let down the end support, support of big dip fully-mechanized mining technology the roof beams and the bedplate can be connected into a whole, by jack and related facilities prevent dumping and slipping down. The second, when support moving height of support-dropping is not more than 2/3 of height of side protective plate, the third, control sequence of support-moving; the fourth, appropriate take oblique to regulate.
(4)End support
End support in the lower part of the working face not only to solve roof control on working face and connection region of conveyor roadway, but also face support thrust gear of conveyor roadway type reversed loader, and form a strong closed space to ensure that safety of men in and out of the end support, into the working face. Therefor we choose three horizontal layout type end support, this have proprietary intellectual property rights, and have better effect. For end support of the working face, because of horizontal layout the use of the conveyor on the end and horizontal layout by reducing mechanism, using the individual hydraulic prop with dip shed support of steel-beam.


Figure 3.2 Diagram of support after

3.3 Safety Protection of Working Face
Due to the large angle of coal seam, in the production process of fully mechanized mining, there is channeling gangue between the supports; side rolling in the working surface; Coal wall spalling, or coal rolling during the process of cutting coal, etc.
Gangue (coals) in the working face solution of safety protection is set the gangue blocking device before frame and between frame.
(1)Gangue Blocking Device Before Frame
In each section of central groove on the conveyor frame (cable groove side) is provided with a lifting jack using gangue blocking plate. The machine road and the working surface (personnel walking and working space) are separated, so that the coal mining machine cut coal and coal wall piece cannot be rushed into the working surface wounding. When observation and treatment of coal mining machine, conveyor, scaffold moving, one or a few pieces of corresponding gangue blocking plate, and then make it raises.
(2)Gangue Blocking Device Between Frame
In the section layout of the hydraulic support of top beam set an upper can lift up and down, and can control the switch of door in the gangue. The door closed, under the rolling down the coal gangue, make the personnel work and walking below from harm, when people pass, open the door. The door goes up and down with the hydraulic support, around the switch with a jack as a driving force.
3.4 Safety protection for export under working face
When the coal seam dip in the working face is more than the slope of the coal, the mining of coal(gangue) accelerated rolling down, arrived at bottom of the working face achieve the fastest speed, largest impact, it is difficult to ensure export under the traffic and the safety of staff maintenance of pillar, prop drawer, and tail of reprint machine, etc.
After repeated research, based on using three horizontal type end support, plate on the end support set plate of blocking the gangue, ensure personnel safety between the support column and rear linkage.
3.5 Organized measures
In order to ensure the smooth implementation of project research work, established a field test research group, members of the senior engineering and technical personnel and management personnel with many years of practical experience. Set up three professional teams in the research group: Field implementation group, technical research group, production coordination and security group. The main responsibilities of each group are as follows:
(1) Field implementation group: In strict accordance with the development of safety technical measures and operation procedures set by the arrangement work, and in a timely manner the problems appeared in the production safety in time to report back to the operation department and technical research group.
(2) Technical research group: According to the actual situation, formulate reasonable equipment installation, retreat technical safety measures and operation procedures in working face.
(3) Production coordination and security group: Equipment and spare parts preparation, standby, maintenance; The management of coal and the supply of water and electricity; equipment maintenance and repair; liaison work between production and management department.

Professional Services from Beijing HOT Mining Tech Co Ltd

*Pre-feasibility study, feasibility study, conceptual design
*Detailed engineering drawing
*Engineering Review and Sourcing Support
*Complete steeply inclined seamlongwall systems supply


Contact us:

	Serena Fu	Kira Zhang	Jotty Jiang	Lolita Liao	Lantis Ye