The method of fully mechanized top-coal caving mining has become the main method of mining thick-seam coal. The process parameters of fully mechanized caving will affect the recovery rate and gangue content of top coal. Through numerical simulation software, the top-coal recovery rate and gangue content, under different fully mechanized caving process parameters, were simulated, and the influence law of different fully mechanized caving process parameters on top-coal recovery rate and gangue content was obtained. A decision model for top-coal caving process parameters was established with a BP neural network, and the optimal top-coal caving parameters were obtained for the actual situation of a working face. On this basis, a in-lab similarity simulation test of the particle material was carried out. The results show that the top-coal recovery rate and gangue content were 86.56% and 3.45%, respectively, and the coal caving effect was good. A BP neural network was used to study the decisions optimizing fully mechanized caving process parameters, which effectively improved the decision-making efficiency thereabout and provided a basis for realizing intelligent, fully mechanized caving mining.

Coal is an important resource for China and even for the whole world. With the improvement of mechanization, automation and intelligence of coal mining equipment in China, there has been an imbalance between the speed of mining and of excavating. Adopting efficient cutting paths is beneficial to improving roadway excavation efficiency and alleviating the imbalance between mining and excavation. In this paper, taking the 12307 belt roadway of Wangjialing Coal Mine as the research background, the geomechanical parameters and distribution characteristics of the surrounding rock were observed and studied, and the test results of in-situ stress, surrounding rock structure and surrounding rock strength were obtained. Based on the test results, a numerical model was established, and the stress and displacement distribution law of the surrounding rock of the roadway under different cutting paths were analyzed, and two optimal cutting paths were proposed based on the actual situation, and industrial tests were carried out. The test results show that using the “snake” cutting path from bottom to top, the roadway section forming effect is good, and a single cycle excavation takes 34 min, which verified the effectiveness of the cutting path design. On the basis of specific engineering geological conditions, excavation equipment and technology, combined with experimental testing, numerical simulation and other methods, the roadway excavation cutting path can be optimized, and the research results can provide a reference for the design of cutting paths for coal mine excavation roadways with the same geological conditions.

For deep-buried thick top-coal roadways under high stress, there exists great difficulty in controlling the stability of the surrounding rock as well as in the necessity for low driving speeds. Taking the return air roadway 20201 (RAR 20201) of the Dahaize Coal Mine as the background, this paper presents a typical engineering case of a deep-buried thick top-coal roadway in a western mine. Through methods such as in situ investigation, theoretical analysis, numerical simulation and engineering practice, we studied the deformation and failure mechanisms of the surrounding rock in a deep-buried high-stress thick top-coal roadway, and revealed the driving speed effect. Results show that compared with shallow buried roadways, the deep-buried thick-roof coal roadway suffers a greater range of damage and failure. The roof damage is so deep that it exceeds the action range of bolts, resulting in the stress transferring to both sides, which affects the stability of the roadway surroundings. The curve of unloading disturbance stress produced by roadway head-on driving is in accordance with the “power exponential” composite function; that is, the faster the driving speed, the less unloading disturbance intensity that is exerted on the roof strata. This paper puts forward targeted cooperative control countermeasures of efficient driving and support in a deep-buried thick top-coal roadway. On one hand, the support efficiency of a single bolt is improved so as to reduce the overall support density; on the other hand, under low support density, the driving-supporting circulation efficiency is also accelerated so as to weaken the unloading disturbance and improve roadway formation speed. Engineering practice shows great control effect of the roadway surrounding rock, and the roadway formation speed is also greatly improved. This research can provide reference for efficient driving and support design in similar deep-buried thick top-coal roadways.

Furfural residue (FR) is utilized directly for bioethanol production without any pretreatment and detoxification. With only 10 FPU g−1 cellulase loading, the glucose yield of FR reached 86.4, 84.6 and 80.5% at solid loadings of 2, 10 and 20%, respectively. When FR is directly used for fermentation, the terminal ethanol concentration achieved at 41 and 57 g L−1 at solid loadings of 20% and 30% (w v−1), respectively. Washing with water enhanced the enzymatic hydrolysis and fermentation of FR. The terminal ethanol of furfural residue washed by 5 times water (WFR‐5) was 48 and 66 g L−1, higher than that from FR. The enhancement is mainly due to the removal of chemical inhibitors and increase of specific surface area. The scanning electron microscope (SEM) showed that FR contained fragmental structure, coarse surface and porous areas. Therefore, FR substrates represented good cellulase accessibility. It indicated that FR could be directly used for glucose and ethanol production without any further treatment. In addition, the quasi‐simultaneous enzymatic saccharification and combined fermentation (Q‐SSF) residues are characterized by fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG).

No abstract