Yang Zhiyong

(Yangchangwan Coal Mine of Shenhua Ningxia Coal Industry Group,Yinchuan,Ningxia 750000)

Abstract:With the rapid development of China's economic construction and modernization, the demand for energy and materials has increased due to its development.Coal is an important energy substance,ranking only next below oil.It plays an important role in the development of China's national economy.In the progress of coal mining of the enterprises,efficiency improving,safety and stability ensuring,utilization strengthening of equipment,safe and efficient mining,etc.,are the prerequisite for their competitiveness.Thanks to optimized mining technologies continuously as well as new various equipments,new technologies and advanced management modes,the mining efficiency of coal mines has been greatly improved.This paper makes an in-depth analysis of the influencing factors of rapid excavation of coal mine roadway,and focuses on the measures for rapid excavation.

Keywords:mining and excavation;coal mine roadway;excavation technology;measure analysis

China is a production and consumption power of the coal.Its coal mining is in the forefront in the world by volume,but the overall mining efficiency is not high with poor mining quality,and the equipment utilization rate is low.This is the current status of coal mining enterprises.How to improve the efficiency and quality of coal mining by using new equipment,new processes and new mining methods is the major development direction of coal mining enterprises.The mining of coal mine roadway is an important way of mining.In the process of roadway mining,the mechanization degree of equipment,the mining method and the management method in the mining process are important factors affecting the efficiency of coal mining.This paper focuses on the processes and methods of roadway mining,and gives a detailed introduction to the measures improving the efficiency of roadway mining and mining quality.

I.Introduction to Coal Mining

(i)Development of coal mines and types of coal mines

The process of coal mining usually consists of two parts: the exploitation of the mine and the excavation of the coal mine.In terms of the development of mines,for example,the underground mine which requires deep excavation of mining passages,direct access to the ore location,and then builds a mining system for the next ore mining.The excavation of coal mines refers to the process of establishing a mining system and equipment installation after ore mining.A certain mining process is applied to mine ore and transport it to a place for delivery.Coal mines are divided into open pit mines and underground mines.Compared with open pit mines,underground mines are more difficult to mine.China's proven coal mines are basically hidden underground.The underground coal mines have the largest storage capacity,but it deeply lies hidden in the earth,so that the mining process,mining management and mining equipment requirements are relatively high as the main direction of development.

(ii)Process of Underground Coal Mining

The mining process of underground coal mine mainly includes the following processes: First,geological exploration.Geological exploration is the first step in underground coal mining.It is necessary to determine the location of the coal seam,the scope of the coal mine,the thickness of the coal seam,the geotechnical structure,and the geohydrologic data to prepare for the roadway construction.Secondly,mine design.According to the results of previous geological exploration, the mine design is carried out to determine the scale of the mine,the number of mines,the process plan,and the mining sequence.Thirdly,underground mining.One could reach the underground coal seam by digging the roadway.Fourthly, roadway layout.The roadway layout of underground mining is the key link,which divides the coal mining area into several mining units and then carries out the next mining step.

Fifthly,recovery.In order to ensure the safety of coal mining,the coal mining process is usually from the end to the rear mining,that is,the coal mining is at the farthest end of the wellhead.After mining,it is getting closer and closer to the wellhead.Coal mining is also known as recovery.Sixthly,ore transportation.After the ore is recovered,it will be transported to a warehouse or delivered to an ore processing plant.Mixing ore refers to the process of uniformly mixing ore during transportation.The waste rock cleaning in the hoist way means to clean and discharge the waste rock generated in the mine road.

II.Major Processes of Underground Coal Mining

(i)Wall Mining

The wall mining means to straight excavate coal mines,and use a one-time long-wall mining process for the thinner ore layer usually.If the ore layer is thick,coal seam will be stratified during the actual coal mining process,and then become thinner and then take the long-arm coal seam for long-wall mining[1].

(ii)Pillar Mining

Pillar mining can be understood as dividing the coal mine into several small mining houses.These mines are connected by channels.After the mining,only one supporting pillar is left.The coal is used according to the shape of these pillars.The method is called column coal mining[2].

III.Major Factors Affecting Excavation Efficiency of Coal Mine Roadway

In the mining process of the coal mine,no matter which mining process is chosen,the roadway layout is required.The layout of the roadway is the key link affecting the speed and efficiency of coal mining,which determines the efficiency of mining and the quality of coal mining.The efficiency of the roadway layout depends on the speed at which the roadway is driven.There are many factors affecting the tunneling speed of coal mine roadway,including the geological conditions of the deposit, the equipment used, the construction technology and management of the constructing organization.The specific factors are as follows:

(i)Geological Conditions

Geological conditions are one of the important factors affecting the speed of roadway excavation.The geological conditions of mine should be surveyed in the early stage of development.The rock type,distribution status, and water pattern of the underground mine have an impact on the tunneling speed.In addition,during the excavation process,the ventilation condition at the top of the roadway is also a factor affecting the efficiency of the excavation[3].

(ii)Excavating Equipment

Equipment is also the main factor affecting the speed of roadway excavation.Different equipments have different tunneling efficiency.The current advanced technology is continuously applied to mining construction equipment,which promotes the improvement of tunneling efficiency.The tooling of the boring equipment,the angle of the excavation and the operating conditions of the equipment are the key to the excavation equipment.In addition,the roadway support process is usually carried out manually,which also reduces the speed of the tunneling.In order to reduce the risk of accidents during the construction process,it is usually adopted to reduce the support top distance and reduce the depth of the rotor depth, which has a great influence on the tunneling speed.

(iii)Excavating Process

The influence of roadway excavation process is mainly reflected in the fact that the excavation and support are always separated, that is, artificial support and rapid excavation.The artificial support time accounts for more than 70%of the tunneling time of the whole roadway,so that the influence of the support technology on the tunneling speed can be seen.Although the support technology is continuously optimized during the construction process,the technical difficulty of the support has been greatly reduced,but it is still an important factor affecting the speed of the excavation[4].

(iv)Management of Constructing Organization

The management of constructing organization in coal mining process is also one of the factors affecting the speed of excavation.The current coal mining enterprises pursue the greatest economic benefits in consideration of short-term benefits.Such problems as less investment in personnel and equipment,aging equipment,lacking of safety in support,and illegal construction of workers,the pursuit of production and speed has brought great hidden dangers to coal mining,ultimately affecting the speed of excavation.

IV.Primary Measures Improving the Speed of Roadway Excavation

The construction of underground mine roadway is different depending on the geological conditions.The process flow, mechanized equipment,transportation method,and the layout of the roadway need to be determined according to the actual conditions of the deposit.No mineral deposits have the same conditions, and the corresponding excavation processes and methods will change.Therefore,the optimal solution should be selected to improve the efficiency of roadway construction and excavation.The main measures are as follows:

(i) Strengthening Geological Exploration in Mining Areas for Excavation Preparing

Geological exploration of coal mines is the basic progress of roadway excavation work.In the exploration process, it is necessary to carry out detailed surveys on the topography,water pattern and climate environment of the mining area for preparation works before excavation.First,geosphere and geological examination.It focuses on the exploration of the geological condition and distribution of the formation rocks.Secondly,geological structure exploration of the mining area.Thirdly,hydrological geology exploration.It includes the groundwater pattern of the mining area,topography,surrounding climate,and environment,etc.The geological exploration of the mine is conducive to understanding the geological structure of the mining area, the distribution of rock and hydrology,and fully preparing for the excavation of the roadway to avoid the impact the excavation work due to geological reasons[5].

(ii) Optimizing Construction Process for Excavation Speed

The optimization of roadway excavation in technology mainly includes the following aspects:First,support mode.The bolting support method is adopted to ensure the excavation speed under the premise of stability support.In the time allocation of support and excavation,the method of excavation first and support latter is adopted to avoid conflicts between support and excavation construction and improve construction efficiency.Compared with other support methods, the bolting support has strong support as well as stable and reliable structure,avoiding the stoppage caused by the support problem,in order to improve the efficiency of the excavation.Secondly, coal transportation.The efficiency of excavation can be improved by using side tipping wagon and coal-extracting methods to replace the traditional ones.Thirdly, blasthole depth.The traditional blasthole depth is about 0.7 meters,while the progress is about 0.66 meters.The depth of the blasthole is low.According to such a blasting method,the excavation speed is too slow,so the depth of the blasthole should be optimized as much as possible.At the same time,in order to ensure the original blasting effect,a scaffold can be placed at a position of about one meter to withstand excess cinder.Optimizing the depth of the blasthole can quickly increase the excavation speed and construction efficiency.

(iii) Introducing Advanced Equipment and Maintaining Equipment Maintenance

The equipment has a significant impact on improving the tunneling speed and constructing efficiency.The coal mine construction enterprises should select the appropriate drilling equipment according to the previous geological conditions in the process of equipment selecting.In addition, the selection of equipment should be based on the level of mechanical automation in order to promote the degree of mechanical and electrical integration of equipment, strengthen the automatic control of equipment,minimize manual operations,and improve the efficiency of excavation.After the equipment is selected,the equipment should be in good working condition and be maintained regularly with a maintenance log.If the equipment fails,the first step should be repairing and finding out the responsible person in order to improve the long-term reliability of the equipment, while avoiding equipment failure caused by long-term overload work,thus affecting the efficiency of tunneling[6].

(iv)Strengthening Constructing Management of Excavation

Strengthening the construction management of excavation is another measure to improve the speed of excavation.First,the incentive and reward system should be implemented.The optimization process should be proposed to ensure safe of employees and avoid quality accidents.It is reasonable to reward the employees who improve the efficiency of excavation.Those who influence the construction progress should be punished.Secondly,technical training should be strengthened.Safety education is essential for mine construction personnel to improve the overall quality of employees.Thirdly,the construction process is in strict accordance with the process documents to strengthen the management of the construction process and ensure the safety of construction.

V.Future Development Trend of Roadway Excavation

The mining technology of modern coal mines in China is developing very rapidly,but there is still a gap with developed countries in comprehensive technology.The future mining technology is mainly oriented towards the development of mechanical automation, focusing on the research and development and innovation of independent technology for the safety of equipment and the construction process as well as mining quality and mining efficiency.First, support equipment and support technology.At present,there are equipments and processes that support and excavation could be done at the same time abroad.Many coal mine equipment manufacturers in China are introducing technology and conducting independent research and development to maximize the efficiency of excavation.Secondly, the use of comprehensive mechanical means for roadway excavating.This kind of method is adopted to excavate roadway with fast tunneling speed and high efficiency.However,the adaptability is poor,and it is necessary to make a reasonable selection according to the results of the geological exploration with a view to improving the efficiency.

VI.Conclusion

Coal is an important energy source supporting China's economic construction,playing an important role in the development of China's national economy.In the mining process of coal mines,the tunneling speed is the key to affect the efficiency of coal mining.In order to achieve rapid excavation in the roadway layout process,it is necessary to strengthen the geological exploration of the mining area,prepare for the excavation,optimize the construction process,and introduce advanced technology equipment.In addition, regular maintenance of equipment and strengthened constructing management and other measures are also essential to improve tunneling efficiency and mining quality and promote the development and progress of coal mining enterprises with economic benefits of coal mining,