Study of characteristics of internal solid-liquid two phase flow field of KYF flotation machine

Dec 2017 / by Fusheng Niu, Yawei Zhao, Jinxia Zhang and Long Wang

According to the complexity of internal solid-liquid two phase flow field of KYF flotation machine, we determine the boundary condition for the numerical simulation of solidliquid two phase flow field, use the mathematical model of discrete solid-zero equation, and standard k-epsilon turbulence model for continuous liquid phase, and explore the impact of different mineral particle sizes, densities and viscosities on characteristics of internal solid-liquid two phase flow field of KYF flotation machine. The results of the research are of the guiding significance and practical application value to further improve the separation effect of flotation machine and develop efficient flotation equipment.
Keywords: Flotation machine, characteristics of flow field, numerical simulation

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Laboratory experiment on 2D inversion of ERT data with different borehole arrangements

Dec 2017 / by Zheng-Yuan Jia, Gang Zhang and Gui-Bin Zhang

This paper discusses the effects of the three types of electrode arrangements on inversion resolution of electrical resistivity tomography (ERT). Through the lab flume (1.2m long and 0.85 deep) experiment and a high-resistivity rock (approximately 1000Ωm) under the low-resistivity salt water (approximately 3Ωm) background, this paper carries out inversion with cross-hole, borehole-to-surface and surfaceto- borehole arrays. The inverted maps from the cross-hole and borehole-to-surface data cannot perform the target well but it can roughly delineate the boundary between the highresistivity and low-resistivity layers. The inversion resolution of the surface-to-borehole data is the worst of the three types. However, the joint data set can increase the inversion resolution without the poor-quality data set being added into the inversion calculation. ERT investigation with borehole-to-surface array was employed in Chifeng in the northeast of Inner Mongolia, China. A smallscale was delineated with high-resolution, which is consistent with the drilling data.
Keywords: Electrode arrangement, electrical resistivity tomography, inversion resolution, joint inversion

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Pozzolanic reactivity and hydration products of quartz

Dec 2017 / by Biyao Geng, Wen Ni, Jiajia Wang, Xiajie Qiu, Xiaowei Cui, Chao Ren, Siqi Zhang and Yi Xing

With quartz, desulfurized gypsum and calcium hydroxide as the materials, this paper studies the pozzolanic reactivity of finely ground quartz and performs XRD, IR, DSC, NMR and SEM analysis on the hydration products of the neat paste specimens. The results show that the compressive strength of the finely ground neat quartz paste specimen is 5.66MPa and 23.49MPa respectively at the age of 3d and 28d, which indicates that the finely ground quartz has the pozzolanic reactivity, and that its main hydration product is C-S-H gel. With the curing age, C-S-H gel and zeolite-like facies continuously increase, and C-S-H gel is produced on the surfaces of quartz particles, gradually make the gaps smaller between quartz particles.
Keywords: Quartz, pozzolanic reactivity, C-S-H gel

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Geological features and H-O-S-Pb isotopes of Au (-Sb-W) deposit in south China’s Xuefeng arcuate mineralization belt

Dec 2017 / by Liangliang Jia, Tagen Dai, Chaozhuang Xi, Dexian Zhang and Richard C. Bayless

Xuefeng arcuate mineralization belt is one of the key goldbearing polymetallic mineralization belts in South China. This paper analyses the sulphide, lead, hydrogen and oxygen isotopes of three typical deposits in the belt. The results show that the δ34S values of Bake gold deposit in the south varies significantly but consistently with the sulphide range of the local Banxi Group stratum, indicating that the mineral-bound sulphide came from the local stratum. To the north, the δ34S values of Zhazixi Sb-Au deposit have a small range as does the northern-most Woxi Au-Sb-W deposit. In particular, the δ34S values of Woxi deposit fall within 2.8‰~-1.5‰, which is consistent with the sulphide content in granite. This means the sulphur mainly originates from magmatite. According to the isotope analysis of hydrogen and oxygen, most of the fluids derived from formation water and meteoric water in the south, and from magmatic water and metamorphic water in the middle and northern parts. Comprehensive analysis of mineralization geology and tectonic evolution leads to the conclusion that the minerals formed in the Early Paleozoic period functioned as the depositional stratum, the mineralization in the Indosinian movements during Jurassic- Cretaceous period was mainly driven by magmatic fluid.
Keywords: Xuefeng belt, isotopes analysis, mineralization, sources

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Propagation mechanism of water-bearing cracks in deep rock mass under blasting disturbance

Dec 2017 / by Xiaoming Lou, Congcong Wang and Wenbin Jian

Based on the principle of fracture mechanics, this paper studies the mechanical model of water-bearing crack development in deep rock mass under blasting disturbance, and derives the expression of the dynamic and static coupling strength of the rock mass. In the meantime, the crack initiation and propagation of tensile shear and compressive shear cracks were investigated to disclose the effect of blasting disturbance, water pressure, geostress and crack angle on crack propagation, and to obtain the formula of crack propagation length. The formula was implemented in a case study. The results show that, in tensile-shear fracture, the geostress accelerates the crack propagation in the same direction; in compressive-shear fracture, the crack inclination angle of the position most vulnerable to compressive-shear fracture varies with the internal friction angle of the rock mass; the blast disturbance load, in a certain sense, elevates the water pressure in the cracks; the crack propagation length decreases in a near linear pattern with the increase in the distance from the explosion source.
Keywords: Static and dynamic coupling, stress intensity factor, fracture toughness, equivalent blasting disturbance load

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Application of grain-based model in simulation of fracture and strength features of brittle rock

Dec 2017 / by Binglei Li and Yongbing Li

Based on the particle flow theory (PFT), the bonded particle model (BPM) and the smooth joint model were combined into a grain-based model, aiming to reveal the micro fracture features of brittle rock. Then, a lattice model was created to reproduce the mechanical properties of the rock, and the samples were under tensile test and uniaxial/triaxial compression under different confining pressures. The tests were conducted to examine the failure mechanism and strength features of the rock. Through the comparison of simulation results and test results, the grain-based model is proved applicable and reliable in the study of mechanical features of brittle rock. During the research, the grain-based model accurately described the crack features of brittle rock in the loading process, and visually reproduced the internal crack development that leads to brittle rock failure. With the ability to simulate brittle material failure of a greater-than- 10 compressive-tensile strength ratio, the proposed model can reveal the entire deformation and failure process of brittle rock.
Keywords: Particle flow theory (PFT), brittle rock, grain-based model, crack, lattice structure

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Analysis of temporal and spatial distribution characteristics of heavy metal in Longjiang river of Guangxi province

Dec 2017 / by Yongxiang Zhang, Yingchun Tang and Bo Ming

By collecting river water and surface sediment samples at 12 sampling sites of Longjiang river in Guangxi province during its wet season, dry season and normal season, the authors analyzed the temporal as well as spatial distribution of heavy metals by measuring the content of Cd, Cu, Pb and Zn elements in both water and sediments. Results show that there exists heavy metal contamination in the Longjiang river to some extent and that in terms of vertical distribution the pollution tends to be reduced. During wet season, heavy metals transform from asdeposited state to suspended state which has the possibility of pollution. In terms of spatial distribution, Cd is the main contamination element in this river and there is Pb pollution to a certain degree.
Keywords: Heavy metal contamination; sediments; Longjiang river

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Study on the pore structure evolution and fractal feature in the process of spontaneous combusiton of coal

Dec 2017 / by Hongfen Zhang, Xiangfeng Shi, Erxin Gao, Shaofei Zhao and Ruihong Zhang

This paper studies the variation of pore structure of coal and the fractal law of pores in two-dimensional and threedimensional space in coal spontaneous combustion using scanning electron microscope and mercury injection experiment. The pore structure of coal changes slowly during 30°C-200°C and there is a great change during 200oC-300°C. The most probable pore size is about 5nm during 30°C-200°C and micropore and transitional pore are dominating. The most probable pore size reaches 310nm at 300°C and macropores and mesopores are dominating during 200°C-300°C. During coal spontaneous combustion, the total pore volume and porosity rise gradually, the specific surface area of pores first rises and then goes down, the permeability goes down first then rises sharply and then goes down, the diameter of the pore with fractal feature gradually goes up and the fractal feature is more and more obvious. Both in two-dimensional and three-dimensional spaces, the fractal dimension of the pore enlarges gradually, indicating that the surface of the coal is becoming more and more coarse and the pore structure is gradually uniform, and the growth rate of fine pore is faster than that of macro pore.
Keywords: Coal spontaneous combustion, pore structure, SEM, mercury injection, fractal dimension

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Research on materials classification model building and procurement strategy of coal enterprises

Dec 2017 / by Hongbo Guo and Yongheng Sun

Materials are the prerequisite for the production of coal enterprises. They belong to consumables and do not constitute product entity. With various types and numerous suppliers, it is more difficult to manage. Therefore, the science of materials management relates to economic benefit of the whole enterprise. To reduce the cost and promote efficiency of materials management, ABCD classification method is proposed by combining with the current problems existed in materials classification of coal industry, algorithm model is built by adopting fuzzy comprehensive evaluation method, with specific description of application process of a specific example provided. Then, the supplier management strategy based on this classification form is proposed on basis of the materials classification, and the test results are favourable, which further reflects the important role of the materials classification in materials procurement.
Keywords: Coal enterprises, fuzzy comprehensive, materials classification

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Numerical simulation study on response characteristics of the different geological models of mine full-space transit electromagnetism

Dec 2017 / by Jun Zhang, Yunbo Li and Xifang Tian

In this paper, it builds the geological simulations models for low resistance abnormity, high resistance abnormity, water flowing fault, water flowing subsided column, water accumulating gob and non-water accumulating gob according to the mine full-space transmit electromagnetic detection theory and by aiming at the several main water inrush structures of mine. Moreover, it gives numerical simulation to full-space transit electromagnetic responses of the several models above by utilizing MATLAB software, and the analytical research results indicate that the mine transit electromagnetism can distinguish the low resistance abnormity more obvious and the high resistance abnormity slightly inferior, especially that simulation detection curve of the water accumulating gob is more obvious. Simultaneously, the induced voltage corresponding to the low-resistance reaction is represented as high potential, and that corresponding to the high-resistance reaction is represented as low potential, and this trend is basically same as that of the half space.
Keywords: Mine full-space transmit electromagnetism, response characteristics, geological model, numerical simulation

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