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Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

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International Journal of mining Science and Technology 2017年第4期27卷 669-673页

作者： Zhou Peiling Zhang Yinghua Huang Zhi'an Gao Yukun Wang Hui Luo Qiang State key laboratory of High-efficient mining and safety of metal mines University of Science and Technology Beijing Ministry of Education

As coal and gas outburst is one of the most serious mine disasters, it is very important to at least control it if not prevent it from occurring. Injecting cement slurry or grouting into the coal seam can strengthen the seam, increase its rigidity coefficient(f), and reduce the volumetric expansion due to gas energy release.This paper reports the results of laboratory experiments on cement-based high water content slurry having different water-cement ratios(W/C) to be used for coal injection. The results show that as the W/C increases, the mobility of the slurry and its setting time increase. The compressive strength and rupture strength, however, are reduced. Furthermore, high W/C grout shows early strength after 7 days, which can be 80% of its 14-day compressive strength. To achieve rapid setting and early strength, the addition of Na_2SiO_3has proven to give the best result, when the concentration of the additive is 3%. The initial and final setting times are 13 and 21 min shorter than samples without Na_2SiO_3, while the compressive strength is more than double. As a retarder, the initial setting time can be extended to 83 min when tartaric acid of 0.4% concentration is added. Through the orthogonal experiment, the optimum recipe of the new high water content slurry has been determined to be: W/C = 2, tartaric acid = 0.2%, Na_2SiO_3= 3%, and12% bentonite. Reinforcement by injection simulation experiments show that the grouting radius of the new slurry mix is 250 mm when the applied grouting pressure is 60 k Pa, 7-day rupture strength and compressive strength are 5.2 and 6.4 MPa, respectively, and are 37% and 88% higher than ordinary cement grout. It can be concluded that the newly developed slurry mix is more effective than the ordinary mix for reinforcing coal and controlling gas outburst.

关键词： Gas outburst Setting liquid Reinforce coal High-water solidified materials Rapid setting and early strength cement Retarder

掺减水剂尾砂膏体充填料浆流变参数的时效性研究

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Journal of Central South University 2022年第4期29卷 1239-1249页

作者：王小林王洪江吴爱祥姜海强彭青松张玺 School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China key laboratory of High-efficient mining and safety of metal of ministry of education University of Science and Technology BeijingBeijing 100083China key laboratory of ministry of education on Safe mining of Deep metal mines Northeastern UniversityShenyang 110000China

采用流变测试方法研究掺减水剂的胶结膏体随时间变化的流变参数,特别关注静态屈服应力和触变性。结果表明,随减水剂用量的增加,胶结膏体的静态屈服应力、动态屈服应力和触变性显著降低,塑性黏度几乎不变。养护时间对掺减水剂胶结膏体的... 详细信息

采用流变测试方法研究掺减水剂的胶结膏体随时间变化的流变参数,特别关注静态屈服应力和触变性。结果表明,随减水剂用量的增加,胶结膏体的静态屈服应力、动态屈服应力和触变性显著降低,塑性黏度几乎不变。养护时间对掺减水剂胶结膏体的静态屈服应力、动态屈服应力和触变性有显著影响,在2 h内分别提高了46.6%~87.1%、15.2%~35.6%和79.4%~138.2%。无减水剂胶结膏体的静态屈服应力、动态屈服应力和触变性在2 h内仅分别提高4.9%、6.3%和16.1%。无论是否添加减水剂,养护时间对胶结膏体的塑性黏度有较大影响,2 h内塑性黏度增大13.2%~19.7%。无论是否添加减水剂,胶结膏体的触变性随静态屈服应力、动态屈服应力呈线性函数增长。研究结果对掺减水剂胶结膏体的管道输送设计有一定的指导意义。

关键词：胶结膏体减水剂养护时间屈服应力触变性

可控硫酸溶液和表面活性剂作用下铜矿石的液体扩散行为及表面润湿性

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Journal of Central South University 2022年第2期29卷 433-442页

作者：艾纯明孙萍萍吴爱祥陈勋刘超 College of safety Science and Engineering Liaoning Technical UniversityHuludao 125105China key laboratory of ministry of education of China for efficient mining and safety of metal mines University of Science and Technology BeijingBeijing 100083China Norin mining Limited Beijing 100053China

为了揭示表面活性剂对提高铜矿表面润湿性的潜在作用,采用高速摄像和图像处理方法,对含表面活性剂硫酸溶液的液滴扩散行为进行了可视化研究,并对固液相互作用进行了探讨。结果表明,液体表面张力和矿石表面粗糙度是影响表面润湿性的主要... 详细信息

为了揭示表面活性剂对提高铜矿表面润湿性的潜在作用,采用高速摄像和图像处理方法,对含表面活性剂硫酸溶液的液滴扩散行为进行了可视化研究,并对固液相互作用进行了探讨。结果表明,液体表面张力和矿石表面粗糙度是影响表面润湿性的主要因素。通过定量铺展面积、铺展系数和接触角,揭示了硫酸溶液浓度和表面活性剂对矿石表面润湿性的影响。液滴铺展实验结果表明,表面活性剂和硫酸溶液的浓度越高,矿石的润湿性越好,铺展系数越大,接触角越小。引入“浸出反应系数”和“表面活性系数”对平衡接触角的数学表达式进行了修正。

关键词：表面活性剂润湿铺展接触角

Comprehensive utilization of solid waste resources: Development of wet shotcrete for mines

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International Journal of Minerals,metallurgy and Materials 2023年第9期30卷 1692-1704页

作者： Yafei Hu Shenghua Yin Keqing Li Bo Zhang Bin Han School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China key laboratory of ministry of education of China for efficient mining and safety of metal mines University of Science and Technology BeijingBeijing 100083China

The development of solid waste resources as constituent materials for wet shotcrete has significant economic and environmental advantages. In this study, the concept of using tailings as aggregate and fly ash and slag powder as auxiliary cementitious material is proposed and experiments are carried out by response surface methodology(RSM). Multivariate nonlinear response models are constructed to investigate the effect of factors on the uniaxial compressive strength(UCS) of tailings wet shotcrete(TWSC). The UCS of TWSC is predicted and optimized by constructing Gaussian process regression(GPR) and genetic algorithm(GA). The UCS of TWSC is gradually enhanced with the increase of slag powder dosage and fineness modulus, and it is enhanced first and then decreased with the increase of fly ash dosage. The microstructure of TWSC has the highest gray value and the highest UCS when the fly ash dosage is about 120 kg·m^(-3). The GPR–GA model constructed in this study achieves high accuracy prediction and optimization of the UCS of TWSC under multi-factor conditions.

关键词： tailings solid waste wet shotcrete machine learning mix proportion

Resistance characteristics of paste pipeline flow in a pulse-pumping environment

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International Journal of Minerals,metallurgy and Materials 2023年第8期30卷 1596-1607页

作者： Haiyong Cheng Zemin Liu Shunchuan Wu Hong Li Jiaqi Zhu Wei Sun Guanzhao Jiang Faculty of Land Resources Engineering Kunming University of Science and TechnologyKunming 650093China key laboratory of ministry of education of China for High-efficient mining and safety of metal mines University of Science and Technology BeijingBeijing 100083China

Paste flow patterns and microscopic particle structures were studied in a pressurized environment generated by a pulse pump.Complex loop-pipe experiments and fluid-solid coupling-based simulations were conducted.The scanning electron microscopy technique was also applied.Results revealed that flow resistance is closely related to pipeline curvature and angle in a complex pipe network.The vertical downward-straight pipe-inclined downward combination was adopted to effectively reduce the loss in resistance along with reducing the number of bends or increasing the radius of bend curvature.The maximum velocity ratio and velocity offset values could quantitatively characterize the influences of different pipeline layouts on the resistance.The correlation reached 96%.Particle distribution and interparticle forces affected flow resistance.Uniform particle states and weak interparticle forces were conducive to steady transport.Pulse pump pressure led to high flow resistance.It could improve pipe flow stability by increasing flow uniformity and particle motion stability.These results can contribute to safe and efficient paste filling.

关键词： pulse-pumping flow state fluid–solid coupling paste filling transportation

Comprehensive recovery of lead, zinc, and iron from hazardous jarosite residues using direct reduction followed by magnetic separation

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International Journal of Minerals,metallurgy and Materials 2018年第2期25卷 123-130页

作者： Ya-yun Wang Hui-fen Yang Bo Jiang Rong-long Song Wei-hao Zhang key laboratory for High-efficient mining and safety of metal mines of ministry of education University of Science and Technology Beijing School of Civil and Resource Engineering University of Science and Technology Beijing

Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rates of lead and zinc and the metallization rate of iron were investigated. The results show that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, and the iron metallization rate was 91.97% under the optimal reduction roasting conditions of a coal dosage of 25.0 wt% and reduction roasting at 1250°C for 60 min. The magnetic concentrate with an iron content of 90.59 wt% and an iron recovery rate of 50.87% was obtained under the optimum conditions in which 96.56% of the reduction product particles were smaller than 37 μm and the magnetic field strength was 24 k A/m. Therefore, the results of this study demonstrate that recovering valuable metals such as lead, zinc, and iron from jarosite residues is feasible using the developed approach.

关键词： jarosite residues recovery direct reduction magnetic separation valuable metals

Mechanical properties and failure modes of stratified backfill under triaxial cyclic loading and unloading

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International Journal of mining Science and Technology 2019年第5期29卷 809-814页

作者： Wang Jie Song Weidong Cao Shuai Tan Yuye School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China State key laboratory of High-efficient mining and safety of metal mines of ministry of education Beijing 100083China

Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area.

关键词： Stratified backfill Triaxial cyclic loading and unloading Mechanical properties Failure modes Deformation modulus

Effect of Na2CO3 and CaCO3 on Coreduction Roasting of Blast Furnace Dust and High-phosphorus Oolitic Hematite

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Journal of Wuhan University of Technology(Materials Science) 2017年第3期32卷 517-524页

作者：曹允业孙体昌 KOU Jue XU Chengyan GAO Enxia School of Civil & Environmental Engineering Key Laboratory of High-Efficient Mining and Safety of Metal Mines Ministry of Education University of Science and Technology Beijing Beijing 100083 China

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.

关键词： Na2CO3 CaCO3 blast furnace dust high-phosphorus oolitic hematite coreduction roasting

Paraffin–CaCl_(2)·6H_(2)O dosage effects on the strength and heat transfer characteristics of cemented tailings backfill

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International Journal of Minerals,metallurgy and Materials 2024年第1期31卷 60-70页

作者： Hai Li Aibing Jin Shuaijun Chen Yiqing Zhao You Ju key laboratory of ministry of education for efficient mining and safety of metal Mine University of Science and Technology BeijingBeijing 100083China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China

The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.

关键词： paraffin–CaCl_(2)·6H_(2)O heat transfer simulation heat calculation phase change material-based backfill latent heat of formula