scholarly journals Experimental Study on Permeability Coefficient in Layered Fine Tailings under Seepage Condition

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Tao Dong ◽  
Ping Cao ◽  
Rong Gui ◽  
Qibin Lin ◽  
Zhizhen Liu
Keyword(s):  
Permeability Coefficient ◽  
Average Particle Size ◽  
Average Particle ◽  
Tailings Dam ◽  
Test Results ◽  
Initial State ◽  
Fine Grained ◽  
Tailings Dams ◽  
Fine Tailings ◽  
Seepage Characteristics

Nearly half of the tailings dams in China are in a state of high-security risks and overservice, and the safety of these tailings dams has always been a concern for relevant scholars. The seepage characteristics of tailings are one of the essential factors affecting the safety of tailings dam. Now, due to the improvement of mineral processing technology, there are many fine tailings dam; the study of the seepage characteristics of the tailings dam is no longer applicable. Fine-grained tailings form uneven deposition in these tailings dams, resulting in the permeability of tailings not conforming to the previous law. Therefore, it is of great significance to study the permeability of fine-grained tailings with uneven deposition. In this paper, the physical model of the simulated tailings dam is established to study the influence of the dry beach slope on the distribution and deposition law of fine tailings during discharge. The test results show that the average particle size of tailings decreases along the length of dry beach, showing the phenomenon of coarsening upstream and thinning downstream. Then, based on the data of fine tailings deposition, the variation characteristics of the permeability coefficient of layered tailings under stable and unstable seepage conditions are studied. The test results show that the variation process of tailings permeability coefficient can be divided into four stages: rapid compaction stage, slow compaction stage, failure stage, and stable stage. Under stable and unstable seepage conditions, the permeability coefficients of unstratified tailing sand are about 10% and 15% higher, respectively, than those in the initial state. The permeability coefficient of layered tailings formed by uneven settlement changes more obviously, which is about 12% and 20% higher than the initial state.

Preparation of fine-grained MgO and Gd2O3 stabilized ZrO2 thin films by electron beam physical vapor deposition co-evaporation

1997 ◽  
Vol 12 (12) ◽  
pp. 3260-3265 ◽  
Author(s):  
F. Tcheliebou ◽  
M. Boulouz ◽  
A. Boyer
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Average Particle Size ◽  
Electron Gun ◽  
Cubic Phase ◽  
Crystallographic Structure ◽  
Average Particle ◽  
Scanning Electron Micrographs ◽  
Dopant Content ◽  
Fine Grained

Thin films of ZrO2 doped with MgO and Gd2O3, 1–1.5 μm in thickness are formed onto nickel substrates by reactive thermal evaporation using a dual-hearth electron gun. X-ray diffraction patterns of the deposits show changes in the crystallographic structure and average particle size as a function of the dopant content. A mixture of monoclinic and tetragonal phases gradually disappears to become a single cubic phase with increasing dopant molar fraction. The average crystallite size deduced from diffraction line broadening decreases as the dopant content increases. This observation is strongly confirmed by scanning electron micrographs which reveal a smooth surface topography. Fine-grained materials obtained here are interpreted in terms of high nucleation rate and kinetically limited grain growth. It appears that composition, crystallographic structure, and microstructure relations are of paramount importance in ZrO2-based films prepared by electron-beam evaporation.

Exchangeable calcium, magnesium and sodium and the dispersion of illites in water. I. Characterization of illites and exchange reactions

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 243 ◽  
Author(s):  
CL Chi ◽  
WW Emerson ◽  
DG Lewis
Keyword(s):  
Surface Area ◽  
Divalent Cations ◽  
Average Particle Size ◽  
Type Equation ◽  
Direct Calculation ◽  
Double Layers ◽  
Average Particle ◽  
Exchange Reactions ◽  
Fine Grained ◽  
Calcium Magnesium

Three 'pure' illites were studied. Two, extracted from soils, were fine grained, and the other coarse, extracted from a shale. The average particle size of each clay was determined from electron micrographs and a specific surface area calculated. For the two soil illites any difference in the surface area deduced from water vapour sorption as compared with nitrogen sorption or by direct calculation, was consistent with the purity of the clay as determined by X-ray diffraction. For the shale, there was a large discrepancy, which is attributed to this illite having a greater surface density of charge. For the two soil illites, the exchange of calcium or magnesium for sodium, over the ESP range 0-12 and the calcium-magnesium exchange isotherms were determined. The exchange of sodium followed the same Gapon-type equation for both clays, and was independent of whether calcium or magnesium was the dominant cation. The calcium-magnesium isotherms were also symmetrical. No evidence was therefore found for calcium ions being more strongly held at exchange sites than magnesium ions. It was shown that in the solutions used to equilibrate the clays, which were 1 mM in divalent cations, diffuse double layers were not formed.

scholarly journals Hydraulic Erosion Rate of Reinforced Tailings: Laboratory Investigation and Prediction Model

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xuanyi Chen ◽  
Xiaofei Jing ◽  
Hai Cai ◽  
Yijun Wang ◽  
Luhua Ye
Keyword(s):  
Potential Energy ◽  
Prediction Model ◽  
Laboratory Investigation ◽  
Erosion Rate ◽  
Failure Modes ◽  
The Self ◽  
Tailings Dam ◽  
Test Results ◽  
Tailings Dams ◽  
Overtopping Failure

Tailings dams are high-potential-energy dams built to store various ore tailings, and the overtopping failure caused by hydraulic erosion is one of the most common failure modes. The characteristics of hydraulic erosion of the reinforced tailings were studied by using the self-made erosion apparatus with four kinds of reinforcement spacing 2.5, 1.7, 1.3, and 1.0 cm, respectively. The test results show a positive correlation between the reinforcement spacing and erosion rate of tailings. Based on the sediment scouring theory, the scouring constant in the erosion rate formula is determined to be 0.056 mm/s; a prediction model for the hydraulic erosion rate of reinforced tailings is established by introducing the collapse coefficient into the results of the overflow test of reinforced tailings. This model can provide a reference for the prediction of overtopping-induced erosion failure of the reinforced tailings dam.

scholarly journals Effects of Geosynthetic Reinforcement on Tailings Accumulation Dams

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 2986
Author(s):  
Changbo Du ◽  
Lidong Liang ◽  
Fu Yi ◽  
Ben Niu
Keyword(s):  
Comparative Analysis ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Earth Pressure ◽  
Good Choice ◽  
Tailings Dam ◽  
Test Results ◽  
Reinforcement Effect ◽  
Tailings Dams ◽  
Over Time

Owing to the complexity of current reinforcement mechanisms, test results from existing models alone cannot provide a basis for the design of new tailings dam reinforcement projects. On-site reinforced tailings accumulation dam testing is thus required to further understand the reinforcement mechanism. In this study, the influence of reinforcement on tailings dams and the variation law of pore water pressure (PWP) and internal pressure (IP) in the dam body after slurry discharge were analysed, and a comparative analysis was performed. The results showed that during the field test, the PWP and internal earth pressure of the accumulation dam after grouting gradually increased over time. Reinforcement can greatly reduce the PWP and IP of the reinforced dam; compared with geotextiles, the reinforcement effect of geogrids is slightly greater. Based on these results, we conclude that geosynthetics are a good choice for strengthening tailings accumulation dams.

scholarly journals Experimental Analysis on Permeability Characteristics of Iron Tailings

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Deqing Gan ◽  
Xi Yang ◽  
Yunpeng Zhang
Keyword(s):  
Particle Size ◽  
Permeability Coefficient ◽  
Void Ratio ◽  
Average Particle Size ◽  
Average Particle ◽  
Fine Content ◽  
Permeability Characteristics ◽  
Permeability Coefficients ◽  
Effective Particle ◽  
The Relationship

The permeability characteristics of iron tailings are one of the important factors affecting the stability of the tailings dam. The permeability properties of undisturbed iron tailings and disturbed iron tailings were analyzed from various aspects such as FC value, gradation, particle size, specific surface area, and interparticle void ratio with water head test in laboratory. The results show that the permeability coefficients of undisturbed iron tailings and disturbed iron tailings are affected by the fine particles content (FC). The threshold of fine content is about 40%. The traditional formulas for calculating the permeability coefficient are applied. But the results are inaccurate. The relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the nonuniform coefficient (Cu), the curvature coefficient (Cc), the average particle size, the weighted average particle size, the specific surface area, and the skeleton void ratio (es) is nonlinear. It is difficult to characterize the change of permeability coefficient when the fine content is large. However, the relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the effective particle size and silt particles void ratio (ef) is linear. A formula was developed for the determination of permeability coefficient of iron tailings by analyzing the effective particle size and silt particles void ratio. And it is more accurate. The permeability coefficients of disturbed samples are slightly larger than the permeability coefficients of undisturbed sample. This is due to the destruction of the sedimentary structure of the tailings and increasing e. Maybe the R in the new formula is affected by the structure of iron tailings. This requires further research.

The Use of Alumina Nanoparticles as Modifiers of Galvanic Binder of Diamond Tools

2014 ◽  
Vol 1040 ◽  
pp. 199-201 ◽  
Author(s):  
N.I. Polushin ◽  
M.S. Ovchinnikova ◽  
A.L. Maslov
Keyword(s):  
Diamond Tool ◽  
Average Particle Size ◽  
Electrical Explosion ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Average Particle ◽  
Test Results ◽  
Aluminum Wire ◽  
Electrochemical Coatings ◽  
Alumina Nanopowder

This article presents results of a study of the surface topography of nickel composite electrochemical coatings (CEC), reinforced alumina nanoparticles, and the test results of the diamond tool. Used as a reinforcing phase alumina nanopowder was obtained by electrical explosion of aluminum wire in oxygenated atmosphere and had an average particle size of 60-70 nm. Experiments showed that the inclusion of alumina nanoparticles in a nickel matrix modifies its structure and increases the strength properties, so the wear resistance of diamond-plating increased by 3 times.

scholarly journals High pressure sintering of TiB2 ceramics at different temperatures

2008 ◽  
Vol 2 (1) ◽  
pp. 9-12 ◽  
Author(s):  
Andrei Kapylou ◽  
Vladimir Urbanovich ◽  
Vladimir Kukareko
Keyword(s):  
High Pressure ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Xrd Analysis ◽  
Internal Stresses ◽  
Average Particle ◽  
Temperature Range ◽  
Fine Grained ◽  
High Pressure Sintering ◽  
Fine Grained Structure

In this paper the effect of high-pressure sintering (HPS) temperature on the microstructure, physical and mechanical properties of TiB2 ceramics has been investigated. Initial TiB2 powder with the average particle size of 5 ?m was sintered in a modified high-pressure anvil-type apparatus under static pressure of 4 GPa in the temperature range of 1400-1800?C. It is shown that HPS allows preparing full-dense TiB2 ceramics with fine-grained structure. The density of samples rises with increasing the sintering temperature up to 1800?C while the maximal microhardness is observed on samples prepared in the temperature range of 1500-1600?C. XRD analysis has shown that this fact is connected with an increase of the level of internal stresses in these samples.

scholarly journals Flocculation Settling Characteristics of Ultra-Fine Iron Tailings with Rich Gypsum

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Daiqiang Deng ◽  
Guodong Cao
Keyword(s):  
Yangtze River Basin ◽  
Average Particle Size ◽  
Chemical Properties ◽  
Average Particle ◽  
Technological Support ◽  
Ecological Protection ◽  
Iron Mine ◽  
Fine Tailings ◽  
The Yangtze River Basin ◽  
Physical And Chemical

Because of the uniqueness of geological mineralization, tailings obtained from Chenchao Iron Mine have low SiO2 content of only 27.80%. Content of Al2O3 and MgO is 13.31% and CaSO4 is 22.09%. The fineness modulus of the ores is large enough for convenient mineral separation, thus resulting in 16.03% −5 μm particles and 27.76% −10 μm particles in the tailings, respectively. The average particle size is only 69.36 μm; it belongs to the category of very fine tailings. The natural sedimentation of tailings is extremely slow due to the comprehensive effects of their physical and chemical properties. Hence, sedimentation tests using four types of flocculating agents are conducted to accelerate the sedimentation of the tailings of Chenchao Iron Mine. Compared with natural sedimentation, the flocculating sedimentation is considerably quicker. Among the four flocculants, the sedimentation of sample using the special BASF flocculant is the fastest. When the tailings of 1 ton add this flocculant of 20 g, the maximum settling concentration reaches 60.98% after 40 min and its special gravity is 1.577 g/cm3, thus it fulfills future requirements of filling technologies. As the largest iron mine in the mid-southern region of China, Chenchao Iron Mine must turn to filling mining. This study can provide technological support for goaf management and environment-friendly treatment of solid waste in the Yangtze River basin, which plays important roles in ecological protection.

scholarly journals Study on Hydraulic Incipient Motion Model of Reinforced Tailings

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2033
Author(s):  
Kehui Liu ◽  
Hai Cai ◽  
Xiaofei Jing ◽  
Yulong Chen ◽  
Lu Li ◽  
...  
Keyword(s):  
Tailings Dam ◽  
Motion Model ◽  
Test Results ◽  
Incipient Motion ◽  
Motion Direction ◽  
Incipient Velocity ◽  
Theoretical Support ◽  
Tailings Dams ◽  
Start Up ◽  
Property Losses

Once the flood overtopping accident of a reinforced tailings dam occurs, it will cause great property losses and serious environmental pollution to the downstream residents. In order to further study the microscopic characteristics of the hydraulic erosion of reinforced tailings dams, considering that the beginning of reinforced tailings particles is the basis of flooding and erosion of reinforced tailings dams, in this paper, a reinforced tailings hydraulic erosion facility was used to carry out the tailings particle start-up test with reinforcement spacing of 5.0, 2.5, 1.7, 1.3, and 1.0 cm, and the influence the law of critical incipient velocity of tailings particles with different reinforcement spacing was revealed. The test results show that, the smaller the reinforcement spacing, the larger the incipient velocity of the reinforced tailings sample. Based on the sediment incipient motion theory, it is assumed that the resistance direction of particle incipient motion is opposite to the particle motion direction. A reinforcement coefficient is introduced to establish the incipient velocity formula of reinforced tailings particles. This model can provide theoretical support for the study of the hydraulic erosion rate of a reinforced tailings dam.

Controlled Preparation and Characterization of Titanium Series Functional Pigment and its Application in Coatings

2017 ◽  
Vol 726 ◽  
pp. 308-315
Author(s):  
Yu Deng ◽  
Jian Xun Zheng ◽  
Qiang Qiang Wang ◽  
Wei Bo Yang ◽  
Song Song Zhang
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Average Particle Size ◽  
Average Particle ◽  
Test Results ◽  
Data Logging ◽  
Powder Samples ◽  
Lower Temperature ◽  
Controlled Preparation

In our recent work, we synthesize several spherical rutile TiO2 powders with different average particle size though hydrothermal method using TiCl4 under lower temperature in a shorter reaction period. Afterwards, solar heat-reflection coatings were prepared by using the TiO2 as pigment. The TiO2 powders were characterized by XRD to determine the phase of crystal. The morphology and particle size were observed by using SEM, and the spectral reflectance of the powder samples and coatings were measured using UV/VIS/NIR spectrophotometer. In order to measure the temperature on the back of coatings, the self-assembled equipment which consisted of solar lamps and surface temperature sensors connected to a data logging system was invented. The test results showed that the shape, average particle size and size distribution were closed-packed state and a bigger mean particle size had higher reflectance intensity. Meanwhile, the reflectance was closely connected to the particle size distribution. Actually, the coatings dispersed TiO2 powder with desired size distribution had excellent performance.

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