scholarly journals Development of Coal Mine Filling Paste with Certain Early Strength and Its Flow Characteristics

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Feng Zhang ◽  
Jinxiao Liu ◽  
Haiming Ni ◽  
Wenxin Li ◽  
Yongle Liu
Keyword(s):  
Fly Ash ◽  
Coal Mine ◽  
Setting Time ◽  
Flow Characteristics ◽  
Coal Gangue ◽  
Practical Significance ◽  
Range Analysis ◽  
Factors Affecting ◽  
Early Strength ◽  
Backfill Strength

In coal mine paste filling technology, geomaterials like coal gangue and fly ash are used as the main component, and cement is applied as the cementing material. In the mining production, mining-and-filling is a cyclic work, where the filling immediately after mining and mining immediately after filling. Long solidification time after filling will affect mining; consequently, the paste should have early strength. In addition, the prepared paste will be conveyed to goaf through the pipeline. The paste flow characteristics will change to some extent in the conveying process, and there is uncertainty about whether the paste can meet the requirements of pumpability and strength. Therefore, the influence of pipeline conveying on flow characteristics of paste before filling the goaf should be taken into consideration. Based on the above two points, this paper studies the paste strength, backfill strength, and pumpability parameters in coal mine paste filling and determines the early and later strength of coal mine paste, as well as the pumpability parameters such as slump degree, segregation degree, setting time, and paste gradation. With the determined mass proportion of coal gangue, fly ash, and silicate cement, the orthogonal test was carried out with three factors including gypsum content, the content of early strength agent (Na2SO4), and the mass concentration, and at three levels. The factors affecting paste flow characteristics were determined by range analysis, and the factors affecting the paste’s early strength were determined by the XRD test and SEM test on its microstructure. With paste proportioning and pipeline conveying simulation system, taking slump, segregation degree, backfill strength, and other parameters as indicators, we obtain the influence law of pipeline conveying on the flow characteristics of paste. The research has great theoretical and practical significance for developing coal paste with early strength and its flow characteristics.

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

2014 ◽  
Vol 988 ◽  
pp. 201-206 ◽  
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.

Experimental Research on Coal Gangue Grouting Material for Gob Filling

2013 ◽  
Vol 357-360 ◽  
pp. 1158-1166
Author(s):  
Tian Feng Gu ◽  
Zhong Di Sun ◽  
Feng Tao Luo ◽  
Kang Guo ◽  
Ya Ming Liu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Compression Strength ◽  
Raw Materials ◽  
Setting Time ◽  
Blended Cement ◽  
Coal Gangue ◽  
Activation Process ◽  
Initial Setting Time ◽  
Wide Range ◽  
Coal Gob

Grouting fill is one of the main methods of coal gob treatment. The grouting properties directly affect the effect of grouting treatment. Cement-fly ash grout is widely used in the treatment of coal gob. But in many gob grouting fill projects, due to the lack of fly ash, we need to look for other low-cost grouting materials. Study was made through laboratory experiment on the properties of cement-coal gangue materials used for the gob grouting. In this paper, the correlation of water-solid ratio, cement content, admixture, concretion compression strength, setting time, viscosity, water segregation rate and hardening rate is discussed in the case of use of large gangue content cement. The test results show that compared with the grout not go through the activation process, the blended cement grout mixed with coal gangue powder activated by low temperature and mechanical crushing has high concretion compression strength. Water glass has a great effect on the viscosity, initial setting time and final setting time, which can be used to adjust the grout properties to accommodate grouting environment requirements. This grout has the advantage of wide range sources of raw materials, and can be used to solve the lack of fly ash and gangue resource utilization problems.

scholarly journals Factors Affecting the Setting Time of Fly Ash-Based Geopolymer

2016 ◽  
Vol 841 ◽  
pp. 90-97 ◽  
Author(s):  
Antoni ◽  
Stephen Wibiatma Wijaya ◽  
Djwantoro Hardjito
Keyword(s):  
Fly Ash ◽  
Initial Temperature ◽  
Ph Value ◽  
Setting Time ◽  
Chemical Properties ◽  
Curing Temperature ◽  
Factors Affecting ◽  
Ph Values ◽  
Physical And Chemical ◽  
And Chemical Properties

Fly ash is a waste from coal burning, that are generated with fluctuation both in its physical and chemical characteristics. This characteristics of fly ash when used in the making of geopolymer concrete will greatly affect the final products obtained. The pH value measured in fly ash, according previous research, can influence the setting time of geopolymer and fly ash with high pH values can cause flash-setting in the concrete. Understanding more clearly about the factors that affect the setting time of fly ash based geopolymer is important for further progress and development of the material. It was found that factors that influence the setting time of geopolymer was not only from the physical and chemical properties of the fly ash itself. Other factors such as composition and mix design, manufacturing process and environmental conditions can also affect its setting time. The experimental results showed that fly ash particle size, CaO and MgO content, in addition to ratio of sodium silicate and sodium hydroxide in the alkali solution, molarity of NaOH, initial temperature of the mixture, curing temperature, and mix volume could potentially influence the setting time of the geopolymer mixture.

Experimental Study on the Compression Rebound Modulus of Coal Gangue Mixture

2012 ◽  
Vol 608-609 ◽  
pp. 1759-1763
Author(s):  
Xian Hai Xu ◽  
Ya Peng Zhang ◽  
Zhi Fei Zhang ◽  
Ju Jun Zhang
Keyword(s):  
Experimental Study ◽  
Regression Analysis ◽  
Fly Ash ◽  
Coal Mine ◽  
Uniform Design ◽  
Regression Equation ◽  
Coal Gangue ◽  
Analysis Model ◽  
Mix Proportion ◽  
Cement Mixture

This experiment was designed by making a coal gangue with coal gangue, fly ash, lime power and a small amount of cement mixture selected from Dongpang coal mine in Hanxing area.We tested the compressive rebound modulus strength of the mixture, and according to the method of uniform design, 8 groups mix ratio were designed and the experiments on the coal gangue mixture in various mix proportion have been conducted. The experimental results were analyzed by regression analysis model, and the regression equation between the compression rebound modulus of coal gangue mixture and the blending amount of each admixture was established. Finally, using this regression analysis model, the influence of the fly ash, calces, cement to strength on the compression rebound modulus of coal gangue mixture was analyzed.

scholarly journals Experimental Study on Fluid Properties of Cement-Fly Ash Slurry Subjected to Multifactors

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Tian Huang ◽  
Feng Huang ◽  
Huifeng Zhou
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Factors Affecting ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Initial Setting Time ◽  
Fluid Properties ◽  
Practical Engineering ◽  
Initial Setting ◽  
The Stability

There are many factors affecting the characteristics of cement-fly ash slurry in practical engineering. Thus, this paper studies the influence of multifactors on the fluid properties of cement-fly ash slurry based on water-cement ratio ( w / c ) (0.75, 1, 1.25, and 1.5), fly ash content (0%, 10%, 20%, 30%, 40%, and 50%) and temperature (20°C, 40°C, 60°C, and 80°C). The bleeding ratio, initial setting time, final setting time, and viscosity were analyzed under coupling conditions. It is found that the water-cement ratio ( w / c ) is the main factor that affects the rheological properties and bleeding rate of slurry. The temperature affects the stability of the slurry in terms that the bleeding ratio of the slurry decreases as the temperature increases. The addition of fly ash enhances the stability of the slurry under different temperature conditions.

scholarly journals Study on Filling Material Ratio and Filling Effect: Taking Coarse Fly Ash and Coal Gangue as the Main Filling Component

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Changxiang Wang ◽  
Yin Liu ◽  
Hao Hu ◽  
Yangyang Li ◽  
Yao Lu
Keyword(s):  
Fly Ash ◽  
Material Selection ◽  
Orthogonal Experiment ◽  
Coal Gangue ◽  
Environmental Benefits ◽  
Filling Material ◽  
Range Analysis ◽  
Filling Materials ◽  
Filling Simulation ◽  
Main Component

Filling mining is an effective way to settle the dilemma of “Three Down and One Above” in coal mining. Fly ash and coal gangue can be used as filling materials with significant social, economic, and environmental benefits. Using coarse fly ash base as cementing material and coal gangue as aggregate, orthogonal experiment of filling paste was conducted in this study. The range analysis was performed for the strength and transportation requirements of filling paste, and the optimum proportion was determined by the comprehensive balance method. In order to verify the filling effect, a dynamic filling simulation device was designed, and a comparative simulation test of caving mining and dynamic filling mining was carried out. Results show that the filling paste with fly ash and coal gangue as the main component can meet the requirements of filling design and application. This research provides a reference for the material selection and proportion design of paste filling.

scholarly journals Pressure Study on Pipe Transportation Associated with Cemented Coal Gangue Fly-Ash Backfill Slurry

2019 ◽  
Vol 9 (3) ◽  
pp. 512 ◽  
Author(s):  
Jie Yang ◽  
Baogui Yang ◽  
Mingming Yu
Keyword(s):  
Fly Ash ◽  
Velocity Distribution ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Solid Particles ◽  
Coal Gangue ◽  
General Description ◽  
Straight Pipe ◽  
Inlet Velocity ◽  
Resistance Loss

Cemented coal gangue-fly ash backfill (CGFB) slurry has commonly been used to control subsidence damage caused by underground coal mining. This paper discusses the characteristics of CGFB slurry fluidity in its pipe transportation. A general description about the components of the CGFB is provided involving the percentage of composition, particle size distribution (PSD) and rheological performance. The CGFB flow characteristics of the slurry pipeline were simulated in a straight pipe and 90° elbow pipe, respectively, combined with the pressure loss and conveying velocity distribution. With the help of the commercial computational fluid dynamic (CFD) code FLUENT, the modeling was conducted with various slurry feeding velocities. These results showed the local resistance loss in a bending pipe is significantly higher than the resistance in a straight pipe under the same conditions associated with CGFB transportation. The velocity distribution of the slurry solid particles in the slurry’s movement forward is more decentralized as the hydraulic inlet velocity increases. Based on these simulation data, a correlation was developed to predict the resistance loss of the CGFB slurry as a function of the hydraulic inlet velocity, pipe diameter and CGFB slurry rheological characteristics.

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