The relevance between water release behavior and pore evolution of hard lignite during the thermal-drying process

He, Qiang; Li, Xinyuan; Miao, Zhenyong; Huang, Shaomeng; Wan, Keji

doi:10.1016/j.joei.2019.01.005

Cited by 11 publications

(5 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, the fitting value of α in the prestressed loading stage was 3.44 which was close to 3.42. The relationship shown in Figure 15 can be modified as follows α α = × e a c 0.13 (12) Therefore, the stress sensitivity change factor η could be introduced to improve the relationship among the permeability, the porosity, and the stress change in the cyclic loading and unloading process. The change factor can be expressed as…”

Section: Resultsmentioning

confidence: 99%

“…Coal is a kind of complex heterogeneous organic matter composed of pores and fractures. , The change in the coal permeability is closely related to the change in the porosity, and even a small change in the porosity may cause an order change in the permeability of coal rocks . Therefore, it is necessary to study the changing trend of the porosity in the changing process of coal permeability.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Study on the Evolution Trend of the Pore Structure and the Permeability of Coal under Cyclic Loading and Unloading

Xin

Wang

et al. 2021

ACS Omega

View full text Add to dashboard Cite

In the deep mining process of coal seams, the mechanical environment of the coal body is complex and in the state of cyclic loading and unloading. The change in the stress state leads to the change in the pore characteristics and the permeability. To investigate the effects of cyclic loading and unloading on the pore characteristics and the permeability of coal, the seepage experiment was carried out for the coal samples using the self-developed triaxial permeation instrument. By pressure confining and continuous cyclic loading and unloading, the evolution of the porosity and the permeability of the coal samples was investigated. Under the condition of the experiment, the influences of the initial value of the confining pressure and the cyclic load amplitude on the evolution of the permeability and the pore structure characteristics of the coal samples were clarified. The experimental results showed that the porosity and the permeability decreased exponentially with an increase in the number of loading and unloading cycles, and this decreasing trend gradually weakened until the porosity and the permeability became relatively stable. When the cyclic load amplitude was the same and the confining pressure increased, the effective porosity of the coal body and the bound porosity decreased. When the confining pressure was the same and the cyclic load amplitude increased, the effective porosity of the coal body decreased and the bound porosity increased. The loss rate of the permeability of the coal samples increased gradually with an increase in the cyclic load amplitude. The same tendency was observed when the cyclic load amplitude was the same, and the confining pressure was different, while the increasing trend was not so obvious. By analyzing the relationship between the porosity and the permeability of the coal samples under different cyclic loading and unloading paths, it was found that the effective porosity and the permeability of the coal samples conformed to the power–law relationship in the process of cyclic loading and unloading, and the change in the cyclic load amplitude had a significant effect on this relationship. The influences of the cyclic load amplitude and the confining pressure on the stress sensitivity of the coal samples were considered, and the change factor of the stress sensitivity was introduced into the relationship between the porosity and the permeability. This relationship was established considering cyclic loading and unloading.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Evolution Trend of the Pore Structure and the Permeability of Coal under Cyclic Loading and Unloading

Xin

Wang

et al. 2021

ACS Omega

View full text Add to dashboard Cite

show abstract

“…China's largest lignite coalfield in Inner Mongolia [ 26,36 ] accounts for 73% of China's lignite reserves. Huolinhe lignite collected from this coalfield is a typical hard lignite.…”

Section: Methodsmentioning

confidence: 99%

“…Extensive research has been conducted on the evolution of the microscopic physical structure (such as the pore structure) of lignite during the drying process, and the structural behaviour is now well understood. He et al [ 26 ] investigated the relationship between water release behaviour and pore evolution during lignite thermal drying and concluded that most of the water exists in pores of 26–100 nm in size, and that the macroporous structure is more likely to be damaged than other pore structures. Feng et al [ 27 ] studied the drying behaviour and pore structure of lignite under different heating rates and drying atmospheres and discussed the relationship between the specific surface area, volume of mesopores and macropores, total pore volume, fractal dimension, and drying characteristics.…”

Section: Introductionmentioning

confidence: 99%

Moisture removal behaviour of single hard lignite particle during drying and quantitative characterization for its surface damage

et al. 2021

Self Cite

View full text Add to dashboard Cite

It is extremely meaningful to study the damage behaviour of lignite for safe operation during the drying process. In this study, a single hard lignite particle (SHLP) was prepared for drying. The drying characteristics of an SHLP were described, and its drying kinetics were studied from the perspective of the drying model and effective diffusion coefficient (Deff). The development of surface cracks in drying were obtained, and the changes in surface damage were quantitatively described by relative crack rate (RCR). The results showed that the drying process for an SHLP was divided into three stages following the slope of the drying curve. The rapid removal of a large proportion of moisture mainly occurred in stage I. The Page model is the best model for describing the drying of an SHLP. In addition, Deff increased with increasing drying time. High temperature promoted the moisture transfer from the inside to the surface of an SHLP. Finally, surface cracks on the SHLP developed rapidly in the early drying stage; specifically, the primary cracks widened and lengthened, and the small cracks mainly attached to the primary cracks. In the later drying stage, cracks shrank and cracks in the branch structure closed. High drying temperature made the RCR of an SHLP reach the maximum value more quickly in stage I.

show abstract

“…At present, low-rank coal has low calorific values and a low utilization rate. Low-rank coal has a porous structure [19], and there are abundant carboxylic acid and phenolic hydroxyl groups on the surface [20], which provide a large number of adsorption sites for the removal of CR [21]. Zhang [22] used lignite to treat phenolic wastewater.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Treatment of Congo Red Dye with Heat Treated Low Rank Coal and Micro-Nano Bubbles

et al. 2022

Self Cite

View full text Add to dashboard Cite

In this study, the adsorption method and micro-nano bubble (MNB) technology were combined to improve the efficiency of organic pollutant removal from dye wastewater. The adsorption properties of Congo red (CR) on raw coal and semi-coke (SC) with and without MNBs were studied. The mesoporosity of the coal strongly increased after the heat treatment, which was conducive to the adsorption of macromolecular organics, such as CR, and the specific surface area increased greatly from 2.787 m2/g to 80.512 m2/g. MNBs could improve the adsorption of both raw coal and SC under different pH levels, temperatures and dosages. With the use of MNBs, the adsorption capacity of SC reached 169.49 mg/g, which was much larger than that of the raw coal at 15.75 mg/g. The MNBs effectively reduced the adsorption time from 240 to 20 min. In addition, the MNBs could ensure the adsorbent maintained a good adsorption effect across a wide pH range. The removal rate was above 90% in an acidic environment and above 70% in an alkaline environment. MBs can effectively improve the rate of adsorption of pollutants by adsorbents. SC was obtained from low-rank coal through a rapid one-step heating treatment and was used as a kind of cheap adsorbent. The method is thus simple and easy to implement in the industrial context and has the potential for industrial promotion.

show abstract

The relevance between water release behavior and pore evolution of hard lignite during the thermal-drying process

Cited by 11 publications

References 44 publications

Experimental Study on the Evolution Trend of the Pore Structure and the Permeability of Coal under Cyclic Loading and Unloading

Experimental Study on the Evolution Trend of the Pore Structure and the Permeability of Coal under Cyclic Loading and Unloading

Moisture removal behaviour of single hard lignite particle during drying and quantitative characterization for its surface damage

Synergistic Treatment of Congo Red Dye with Heat Treated Low Rank Coal and Micro-Nano Bubbles

Contact Info

Product

Resources

About