Reduction of surface subsidence risk by fly ash exploitation as filling material in deep mining areas

Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed in this study. We used laboratory tests to study how the fly ash (FA) content, cement content, lime–slag (LS) content, and concentration influence the transportation and mechanical properties of aeolian-sand-based cemented filling material. The internal microstructures and distributions of the elements in filled objects for curing times of 3 and 7 days are analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The experimental results show that: (i) the bleeding rate and slump of the filling-material slurry decrease gradually as the fly ash content, cement content, lime–slag content, and concentration increase, (ii) while the mechanical properties of the filled object increase. The optimal proportions for the aeolian sand-based cemented filling material include a concentration of 76%, a fly ash content of 47.5%, a cement content of 12.5%, a lime–slag content of 5%, and an aeolian sand content of 35%. The SEM observations show that the needle/rod-like ettringite (AFt) and amorphous and flocculent tobermorite (C-S-H) gel are the main early hydration products of a filled object with the above specific proportions. After increasing the curing time from 3 to 7 days, the AFt content decreases gradually, while the C-S-H content and the compactness increase.

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Research on the Application of Fly Ash in High Water Filling Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.807-809.1124 ◽

2013 ◽

Vol 807-809 ◽

pp. 1124-1128

Author(s):

Feng Yi Li ◽

Lei Chen ◽

Guang Qi Li ◽

Wei Xin Chen ◽

Peng Fei Wang

Keyword(s):

Fly Ash ◽

Power Plant ◽

High Efficiency ◽

High Water ◽

Packing Material ◽

Filling Material ◽

Comprehensive Utilization ◽

Push Forward ◽

Water Filling ◽

Utilization Ratio

Fly ash is a coal-fired waste from the coal-consumed power plant. It has become a great concern as to how fly ash should be treated properly at home. At present, the comprehensive utilization ratio of fly ash is just 30% and utilization ratio of fly ash from coal gangue power plant is less than coal-fired power plant. The effect of different fly ash added to the high-water filling material on the filling result was analyzed and field test of filling in mined-out area was conducted in the Babao vertical shaft + 3211 section of Tonghua coal mining group. The result shows that fly ash of gangue power plant added into the high-water packing material can lower the filling material cost effectively. This research can lead to push forward the utilization of fly ash with high efficiency.

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Study on the Strata Movement Rule of the Ultrathick and Weak Cementation Overburden in Deep Mining by Similar Material Simulation: A Case Study in China

Mathematical Problems in Engineering ◽

10.1155/2020/7356740 ◽

2020 ◽

Vol 2020 ◽

pp. 1-21 ◽

Cited By ~ 1

Author(s):

Guojian Zhang ◽

Guangli Guo ◽

Yi’nan Lv ◽

Yaqiang Gong

Keyword(s):

Material Model ◽

Failure Pattern ◽

Central China ◽

Western China ◽

Scale Transformation ◽

Similar Material ◽

Deep Mining ◽

Mining Areas ◽

Sandstone Formation ◽

Strong Control

In the deep mining areas of western China, there exist ultrathick and weak cementation strata in the overburdens above the Jurassic coal seams, and the overburden lithology is generally moderately a little weaker than the medium-hard strata. Yet, the practical measurement indicates that the surface movement rule in this area displays the specialty that is apparently inconsistent with its lithology, which increases the uncertainty of safe production in coal mines. In this study, the similar material and numerical simulations were conducted to investigate the movement rule and failure pattern of the ultrathick and weak cementation overburden. In addition, the photographing scale transformation-time baseline parallax (PST-TBP) method was used to monitor the similar material model to makeup for the lacks of Xi'an Jiaotong University Digital Close-range Industrial Photogrammetry System (XJTUDP) software. The findings of this study can be summarized as follows. (1) To some extent, the PST-TBP method can makeup for the deficiency of the XJTUDP software because the measurement accuracy of the PST-TBP method is 0.47 mm. (2) The height of the caving zone is approximately 66 m, and the height of the water suture zone is about 112 m, which is obviously larger than that of the medium-hard and soft overburden in eastern-central China. (3) The first breaking span of the immediate roof reaches 120 m, the cyclic fracturing length is about 60 m, and the separation occurred at 43 m and 66 m above the coal seam. (4) The failure pattern of the ultrathick and weak cementation overburden is “beam-arch shell,” and the failure boundary is arch. (5) The Zhidan group sandstone and Jurassic sandstone formations have strong control effects. The Zhidan group sandstone is the main control stratum and the Jurassic sandstone formation is the secondary-control stratum. The research results provide an insight into guiding the safe mining of deep coal in the ultrathick and weak cementation overburden.

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Study on the Properties of Pumping Gangue Filler

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.1164 ◽

2011 ◽

Vol 287-290 ◽

pp. 1164-1167

Author(s):

Yue Zhong Lin ◽

Dong Cai Lin

Keyword(s):

Fly Ash ◽

Research And Development ◽

Portland Cement ◽

Coal Gangue ◽

Filling Material

As reinforcement of goaf filling needs, filling material mined area become the focus of research and development. This study used PO42.5 Portland cement, fly ash, coal gangue, preparation meets the requirements of good performance out of the strength of pumping gangue filler.

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Study on Basic Experiment of Coal Waste Paste Filling Material

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.174-177.384 ◽

2012 ◽

Vol 174-177 ◽

pp. 384-389 ◽

Cited By ~ 1

Author(s):

Xin Guo Zhang ◽

Ning Jiang ◽

Heng Wang ◽

Yang Yang Li

Keyword(s):

Fly Ash ◽

Coal Mine ◽

Coal Waste ◽

Hydration Reaction ◽

Filling Material ◽

Hydration Products ◽

Xrd Diffraction ◽

Speed Up ◽

Diffraction Patterns ◽

Cementing Material

Based on present situation that coal mining under buildings, water bodies and railways, and solid wastes mainly including coal waste, fly ash in coal mine of our country, optimization proportioning of paste filling material and hydration reaction mechanism is systematicaly researched combining with project practice of paste filling in Daizhuang Coal Mine, Zibo Mining Group. The result shows that: Proportioning design P10 can be used as the optimal proportion results, the rate of cementing material is that the proportion: fly ash: coal waste is 1:4:6, quantity concentration is 74%; Coal waste paste XRD diffraction patterns of different instar shows that its hydration products at different instar stage are mainly gelation of CH, Aft and C-S-H; Relative content of each material in hydration products is different at different instar stage; With scanning electron microscope a certin ettringite is producted after coal waste paste hydrated 8h, and content of C-S-H gelation and CH gelation is increased gradually; Hydration process of portland cement is speed up and the strength of paste is enhanced.

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Research on Mining Water-Rich Fly-Ash-Based Filling Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.988.201 ◽

2014 ◽

Vol 988 ◽

pp. 201-206 ◽

Cited By ~ 1

Author(s):

Wei Xin Chen ◽

Feng Yi Li ◽

Xian Hua Guan ◽

Lei Chen ◽

Wen Bo Nie

Keyword(s):

Fly Ash ◽

Industrial Waste ◽

Setting Time ◽

Physical And Mechanical Properties ◽

Filling Material ◽

Metal Mine ◽

Early Strength ◽

The Cost ◽

Cementing Material ◽

Early Activity

It had decades of history that cementing material was used for filling in coal mine or metal mine goaf, which was a common filling material in recently filling mining. Paste and high water material have excellent performance, but the price was too high, which restricted the development of cemented filling technology severely. Later, fly ash and other industrial waste were mixed into the cementing material in order to reduce the cost, but because of which early activity was low, the early strength was reduced by mixing too much fly ash and other industrial waste, the setting time was extended, which affected the filling effect seriously. Therefore, it becomes a key problem that how to excite the early activity of fly ash. It was a breakthrough to select the appropriate activator and activation method, because of the difference mechanism of action and effects for different activators of fly ash, the complexity composition of filling material mixed with large number of fly ash, and the early and late physical and mechanical properties [1,2].Four salts are used for activators in this paper, which are mixed with fly ash and water, and a display method was selected to maximum activate the activity of fly ash, increase the early strength of the material, and reduce the cost of the material.

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Study on Surface Subsidence Law Induced by Deep Mining of Large Steep Metal Deposit

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.2902 ◽

2013 ◽

Vol 295-298 ◽

pp. 2902-2905

Author(s):

Yan Hui Guo ◽

Ke Peng Hou

Keyword(s):

Surface Deformation ◽

Three Dimensional ◽

Mining Area ◽

Surface Subsidence ◽

Ground Movement ◽

Technological Problem ◽

Underground Engineering ◽

Deep Mining ◽

Displacement Angle ◽

Dimensional Simulation

To solve this difficult technological problem that predicts the surface subsidence that induced by deep mining of large steep deposit. Through understanding engineering geological characteristics and mining conditions for a certain mining area, the three-dimensional simulation model of deep mining with a high degree similarity in space and mechanics morphology have been established, and the exploitation of the mining area has been systematically simulated. After excavation of the third stage, the calculated values of surface subsidence coincided with the measured values of GPS. Then it has been more accurately predicted surface subsidence and displacement angle and the range of surface deformation which were induced by deep mining in fourth stage project. It provides the basis for the positioning of underground engineering and design of the range of ground movement in deep mining.

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Study on the Structure Model and Controlling Method of Subsidence in Flat Seam and Deep Mining

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.306-308.1403 ◽

2006 ◽

Vol 306-308 ◽

pp. 1403-1408 ◽

Cited By ~ 1

Author(s):

Chong Ge Wang ◽

Wei Zhong Chen ◽

Liyou Pan

Keyword(s):

Research Work ◽

Surface Subsidence ◽

Deep Mining ◽

Global Positioning ◽

Coal Wall ◽

The Face ◽

Surface Subsidence Control ◽

The Common ◽

And Control ◽

Overlying Strata

The stratum movement and surface subsidence is considered as a whole system in the research work. The key of the surface subsidence control lies first in having thorough knowledge of the dynamic changeable of the overlaying strata movement as the face advances so as to establish the corresponding structure mechanics subsidence model in flat seam and deep mining. The common characteristic of stratum movement and the development procedure of crack arch are described in this paper. The structure constituents of subsidence and their influencing factors are also analyzed. Meanwhile, the surface subsidence is determined by the compressing of coal wall and the bending of the overlying strata. Based on the ground observation by the global positioning system, the boundary angle and the motion angle are determined. Furthermore, according to the research law, one can predict and control the surface subsidence damages for the special geologic conditions.

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