Backfill Mining Technology Research Articles

Design and application of solid, dense backfill advanced mining technology with two pre-driving entries

New solid backfill mining technology provides unique technical advantages for “three-under” coal mining which refers to coal resources trapped under buildings, railways, and water bodies. This technology has a much higher recovery rate and can effectively control the surface subsidence. However, successful application of this technology depends heavily on geological conditions. To avoid the disadvantages associated with downward mining and overhead backfilling with this new technology, a new advanced solid backfill mining design with two pre-driving entries is proposed here to ensure the backfill effect. Taking Huayuan coal mine as an example, this paper tests the double gob-side entries retaining with no pillar left scheme and optimizes an integrated technology setup for backfill mining and gob-side entry retaining. Field applications show that the recovery rate increased from 40% for strip mining to 85% for backfill mining. Moreover, the new backfill technology allowed for better control over the surrounding rock deformation caused by the gob-side entry retaining effect and better control of ground subsidence as compared to strip mining.

Subsidence prediction method based on equivalent mining height theory for solid backfilling mining

Based on the characteristics of strata movement of solid backfilling mining technology, the surface subsidence prediction method based on the equivalent mining height theory was proposed, and the parameters selection guideline of this method was also described. While comparing the parameters of caving mining with equivalent height, the subsidence efficient can be calculated according to the mining height and bulk factor of sagging zone and fracture zone, the tangent of main influence angle of solid backfilling mining is reduced by 0.2–0.5 (while it cannot be less than 1.0). For sake of safety, offset of the inflection point is set to zero, and other parameters, such as horizontal movement coefficient and main propagation angle are equal to the corresponding parameters of caving mining with equivalent height. In the last part, a case study of solid backfilling mining subsidence prediction was described. The results show the applicability of this method and the difference of the maximum subsidence point between the prediction and the observation is less than 5%.

Analysis and Application of Pumping Waste Filling Material Performance

Based on the important role in aspects of Backfill mining technology in mining to resolve the deep pressure , maintain the slope steady, control the surface sinking and protect the ecological environment, this article probes the relationship between filling material strength to gangue for coarse aggregate ,to coal ash for fine aggregate, to cement and waterglass for binder and influencing factors, and researches the strength properties and the deformation properties of filling objects used for engineering practice, which gets good filling effect. The results showed that the filling material having a high early strength and high elastic modulus, when compressed it performance plastic hardening characteristics; under certain conditions of the concentration by mass and the amount of coal ash, filling mass showing the approximate linear relationship between the compressive strength and natural curing time, Under the same condition, cement + water glass as cementitious material filling mass is significantly higher than only with cement as a cementitious material in the strength.

INDUSTRIAL TESTS OF WASTE ROCK DIRECT BACKFILLING UNDERGROUND IN FULLY MECHANIZED COAL MINING FACE

For efficient, economical and environmentally disposing the waste rock underground, based on principles of waste direct backfilling in fully mechanized coal mining, this paper carries out a field test in 6304-1 working face of Jining No.3 Coal Mine. We first design a waste rock direct underground processing system, including screening-crushing system, transportation system, transfer system, stope backfilling system and coal mining system. Then optimize the waste backfilling and coal mining technology, update the waste backfilling process with start backfilling from backfill scraper conveyor s head to tail, gradually uplift tamping arm, gradually compact backfill materials, move backfill scraper conveyor forward when the tamping arm can t extend out and last fill roof gap by up material pushed by down material . At last, imply this system and check strata movement controlling effect by actual measuring the roof dynamic change law, which supported by the dense backfill body. The results show that the test working face can cut 0.6 million tons of raw coal one year, and direct backfill 0.74 million tons of waste rocks at the same time, and the maximum subsidence of immediate roof observed in situ is 340mm, the maximum caving speed is

Implementation of paste backfill mining technology in Chinese coal mines.

Implementation of clean mining technology at coal mines is crucial to protect the environment and maintain balance among energy resources, consumption, and ecology. After reviewing present coal clean mining technology, we introduce the technology principles and technological process of paste backfill mining in coal mines and discuss the components and features of backfill materials, the constitution of the backfill system, and the backfill process. Specific implementation of this technology and its application are analyzed for paste backfill mining in Daizhuang Coal Mine; a practical implementation shows that paste backfill mining can improve the safety and excavation rate of coal mining, which can effectively resolve surface subsidence problems caused by underground mining activities, by utilizing solid waste such as coal gangues as a resource. Therefore, paste backfill mining is an effective clean coal mining technology, which has widespread application.

Research on the Belt Loader Waste Rock Gravity Backfill Mining Technology

Backfill mining is an important technology of surface subsidence control and green mining. This paper analyzes the application condition and filling effect of waste rock gravity backfill mining, it also introduces a new waste rock gravity backfill mining technology which utilizes belt loader to transport waste rock to goaf. Belt loader waste rock gravity backfill mining can consume waste rock and achieve environmental protection, it also has the advantages of low filling cost, simple filling system, low labor intensity and safety, etc, so it can be promoted and applied in collieries widely.

Advance of mining technology for coals under buildings in China

In China there are large amounts of coal located underneath buildings. In this article the severity of the problem is studied, and the characteristics of the mining technology used for the extraction of coals under buildings are described. Based on the comprehensive analyses of the abundant literature, separated bed grouting, backfill mining, Partial Mining and homonic mining technology, are the main mining technologies that exist for extraction of these coals. At the same time, the necessary measures for protecting the buildings are also considered. In particular, the authors have analysed the development of these mining technologies and concluded that the waste filling will be the focus of development, and that the main developing technologies of the filling mining method should be further perfecting the separated bed filling, strip mining and strenthening the anti-deformation of building.

Current Situation and Prospect of Coal Backfill Mining Technology

This paper introduces the classification of the coal backfill mining method and analyzes current technology statuses of several coal backfill mining technologies: waste backfill mining technology, paste backfill mining technology and abscission layer grouting backfill mining technology. Based on the analysis of current backfill mining technology statuses, this paper puts forth that the backfill mining technology should focus on the problem of the lack of coal backfill mining capacity, research on the role of backfill mining rock movement needing to be strengthened, filling efficiency and economy needed to improved through reasonable optimization of backfill mining parameter, so it can provide the theoretical basis for backfill mining design.

Backfilling technology and strata behaviors in fully mechanized coal mining working face

Based on the principle of fully mechanized backfilling and coal mining technology and combined with the Xingtai Coal Mine conditions, we mainly optimized the coal mining equipment and adjusted the coal mining method in the Xingtai Coal Mine 7606 working face for implementation this technology. Firstly, we define the practical backfilling process as the “(from backfilling scraper conveyor’s) head to tail backfilling, step by step swinging up of the tamping arm, gradual compacting, moving formed backfilling scraper conveyor when the second tamping arm cannot pass and connecting the immediate roof by back material push front material movement”. Meanwhile, the stress changes of backfill body in coal mined out area was monitored by stress sensors, and the roof caving law was analyzed by monitoring the dynamic subsidence of −210 west roadway of this face. The site tests results show that using this new backfilling and coal mining integrated technology, the production capacity in the 7606 working face can reach to 283,000ton a year, and 282,000ton of solid materials (waste and fly ash) is backfilled, which meets the needs of high production and efficiency. The goaf was compactly backfilled with solid material and the strata behavior was quite desirable, with an actual maximum vertical stress of the backfill body of 5.5MPa. Backfill body control the movement of overburden within a certain range, and there is no collapses of major areas in the overlying strata upon backfilled gob. The maximum subsidence and speed were 231mm and 15.75mm/d respectively, which proved the practical significance of this integrated technology.

Subsidence control and farmland conservation by solid backfilling mining technology

Solid backfilling mining technology, which decreases the height of fissure zone and caving zone, and alleviates the subsidence, is a new technology for farmland conservation. Based on the situation analysis of farmland destruction in mining area, three ways for farmland protection were proposed. In order to improve the feasibility of this technology, the limited filling materials should be used to increase resources recovery ratio, and then the surplus materials could be backfilled into goaf. An index, namely farmland conservation ability, was put forward to optimize the ways for farmland conservation. At last, the Wanbei coal mine was taken as a case for farmland conservation. It was shown that 3240 t dull coal was substituted and 52 hm 2 farmland was conserved by solid backfilling mining in this coal mine.

Coupling mechanism of roof and supporting wall in gob-side entry retaining in fully-mechanized mining with gangue backfilling

We analyzed the deformation characteristics of overlying stratum in backfilling with fully-mechanized and retaining roadways along the gob area coal mining technology, and established a mechanical model for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully-mechanized coal mining technology. Using Winkler elastic foundation theory, we analyzed a part of the key stratum under the action of elastic foundation coupling problem, and derived deflection analytical expressions. Combined with specific conditions, we obtained the deflection curves for the roof key stratum of retaining roadways along gob under the conditions of backfilling and fully-mechanized coal mining technology. On this basis, we adopted the Coulomb’s earth pressure theory to solve the problem of lateral pressure of the gangue filling area on the supporting wall beside the roadway and to provide the theoretical basis for reasonable selection of the distance between gangue concrete wall and roof and further discussion on the supporting stability of roadway.

Impact law of the bulk ratio of backfilling body to overlying strata movement in fully mechanized backfilling mining

Fully mechanized backfilling mining technology with waste, fly ash, and loess, etc. provides advantages of safety and high efficiency to the extraction of coal under buildings, railways and water bodies. In this paper, the bulk ratios of backfilling bodies with different waste and fly ash mixture ratio was analyzed with MTS815.02 electro-hydraulic servo rock mechanical testing system and compacting device, the optimal mixture ratio of waste and fly ash was determined, and it proposed that the backfilling body should be firstly compacted after being backfilled into the goaf. With numerical simulation, the impacts of bulk ratio of waste and fly ash backfilling body to overlying strata movement law and surface subsidence controlling in backfilling mining were analyzed, and it figured out the bulk ratio of backfilling body that could ensure a reasonable range of surface subsidence. Finally, the engineering application confirmed that the strata movement controlling in fully mechanized backfilling mining was more effective, the surface buildings and facilities were not severely influenced. The above achievements could provide technical reference for the successful implementation of fully mechanized backfilling mining.

The Application Research on Backfill Mining Technology of Gangue for Coal Pillar Mining in Xingtai Mining Village

Gangue and fly ash combined mining technology is the direct filling of the gangue and fly ash to the surface by the feed delivered to the face well, and then filling is in gob areas, while ensuring under the premise of the safe use of surface buildings subjects to the normal maximum level for achieving Coal Mining under the buildings. In the paper, gangue and fly ash on the exploitation of the feed system were designed for filling and compaction equipment, the hydraulic mining was developed on the backfill mining, the conveyor was modified, and the gangue and fly ash mining technology were designed. As the result, the filling rate and surface subsidence was controlled effectively, the service life of the mine was extended, and the good economic and social benefits were achieved.

Review of backfill mining practices and technology at the fox mine : Ford, R A Proc 12th Canadian Rock Mechanics Symposium, Sudbury, Ontario, 23–25 May 1978, P1–9. Publ Montreal: CIMM, 1978

Review of backfill mining practices and technology at the fox mine : Ford, R A Proc 12th Canadian Rock Mechanics Symposium, Sudbury, Ontario, 23–25 May 1978, P1–9. Publ Montreal: CIMM, 1978