Li S.-L.,Xiamen University |
Tang H.-Y.,Changsha Institute of Mining Research
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010
Experiments on acoustic emission (AE) characteristics of full-regime rock failure are carried out with stiffness test machine (MTS) under uniaxial loading, cyclic loading-unloading conditions to obtain the relations of stress-strain, stress-time-accumulative counts of AE, stress-time-AE rates. Based on the test results, the AE characteristics of loading process, unloading and reloading of loading-unloading process are analyzed. The results show that AE phenomena can apparently appear during the process of unloading. When being reloaded under the stress level not more than 50% of the peak stress, there are less or little AE counts occurring as long as the stress level is not more than the previous loading stress level, that means the Kaiser effect occurs. While reloading is made again on the stress-level of over 60% of the peak stress, there occurs obviously AE events, that is so-called the Felicity phenomenon. Rock samples show a large amount of AE events in the post-peak region for both loading and loading-unloading processes. And the results also show that there exists a relatively tranquil period phenomenon of AE for all samples of the style of AE abruptly increasing during middle stress stage.
Peng F.-H.,Changsha Institute of Mining Research |
Li S.-L.,Xiamen University |
Cheng J.-Y.,China Molybdenum Co. |
Jia B.-S.,China Molybdenum Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014
By using the digital multi-channel microseismic monitoring system, the characteristics of blast stress wave propagation in deep complex and mined-out area and upper fractured rock mass are tested. The wave velocity is acquired by the curve fitting method, which uses the P wave triggering time and propagation distance. The results show that the wave velocities in deep complex and mined-out rock mass and upper coagula rock mass are obviously different. Fitted the curve by using the stress wave amplitude and propagation distance, it is found that the stress wave amplitude decreases in the form of power when the propagation distance increases. By using the signal spectrum analysis and filtering, the attenuation coefficient and frequency are in cubic polynomial relations, and the attenuation of the high-frequency wave is more obvious. The average quality factors in deep complex and mined-out area and upper fractured rock mass, are calculated and they are 4.055 and 2.478, far less than those of the original rock mass, indicating that the mined-out area and fracture have great influence on the stress wave propagation.
Wei S.,Hunan University of Technology |
Xu X.,Changsha Institute of Mining Research |
Liu Y.,Hunan University of Technology |
Yang J.,Hunan University of Technology
Materials Chemistry and Physics | Year: 2011
A novel and facile method to prepare hydrophobic nano-silver colloid and aqueous coordinate was proposed. Chemical reduction of silver nitrate in a tributyl phosphate (TBP) solution containing polyvinylpyrrolidone (PVP) was conducted and stable hydrophobic nano-silver/TBP/PVP colloids were obtained. Adopting a phase transfer process, the as-prepared colloids can be diverted into an aqueous system to obtain hydrophilic nano-silver colloids. The resultant materials were characterized by digital camera, TEM, XRD and UV-vis spectra. The results show that the reaction can be accomplished fast at room temperature and the synthesized colloids can remain stable for a long time, and the mean diameter of silver particles is around 10 nm for both nano-silver colloids. The nano-silver crystalline is face-centered cubic (fcc) structure, and the UV-vis absorbance peaks are at 412 and 420 nm for aqueous nano-silver and nano-silver/TBP/PVP colloids respectively. © 2010 Elsevier B.V. All rights reserved.
Zhang Y.,Memorial University of Newfoundland |
Liu Q.,University of Alberta |
Li L.,Changsha Institute of Mining Research
Hydrometallurgy | Year: 2016
Iron removal is a common procedure in hydrometallurgy of non-ferrous metallic ores. Chemical precipitation and solvent extraction are currently the main methods employed for separation of iron from copper leach solution. However, chemical precipitation methods have the problem of producing large amounts of iron precipitates, and/or requiring high temperature and high pressure conditions for precipitation. The precipitates are difficult to separate from the solution. Emulsification is a general problem for solvent extraction, which causes loss of extractants and contamination of the electrolyte. A common problem for solvent extraction and chelating ion exchange processes is the difficult iron stripping process. Therefore, finding an efficient and environmentally friendly method for iron removal is of great significance. In this paper, new processes of using ion exchange resins to remove iron from copper leach solution have been investigated. Salicylic acid, amino carboxylic acid, amino phosphonic acid and hydroxy-oxime resins were employed to adsorb iron from a synthetic copper leach solution containing 40 g/L of Cu2 + and 36 g/L of Fe3 +. It was found that a hydroxy-oxime resin, named Z-Fe, has excellent adsorption selectivity on Fe3 +. Desorption behavior of the resin was studied by two step elutions using dilute H2SO4 and oxalic acid solution, respectively. After optimizing the adsorption-elution processes, the extent of removal of iron from the simulated copper leach solution using resin Z-Fe was 89.83%, while copper recovery could reach 100% in closed circuit processing. © 2016 Published by Elsevier B.V. All rights reserved.
Yin X.-G.,University of Sichuan |
Yin X.-G.,Changsha Institute of Mining Research
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2010
The full failure, of loading rock samples and concrete samples were tested and its mechanics characteristics and Acoustic Emission (AE) characteristics were studied. The curves of mechanics characteristics and AE accumulative total and AE rate of concrete and rock failure were got. And the AE features including the relationships between AE and time, AE and stress were studied. By comparing the AE characteristics between rock, their different and similar AE characteristics were pointed out. The time-consuming phenomenon was discussed to both rock samples and concrete samples whose plastic deformation is obvious when stress is close to peak value strength at the process of one time loading. It was pointed out that the AE rate of those samples which have this time-consuming phenomenon will be declined and AE quietude will also appear in this stage. But for brittle rocks, neither this time-consuming phenomenon nor AE quietude will appear. In addition, the value of the parameter of time was analyzed and summarized in AE monitoring and studying. Time parameter should be paid more attention to in AE studying despite it could be ignored in general indoor rock mechanics experiment research.
Liu X.,Central South University |
Yu T.,Central South University |
Wei Q.,Central South University |
Yu Z.,Central South University |
Xu X.,Changsha Institute of Mining Research
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012
Nanodiamond seeding is a well-established approach to enhancing the nucleation density in chemical vapor deposition (CVD) diamond growth. However, the effects of nanodiamond seeding are highly dependent upon the dispersion properties of nanodiamond particles, the solvent and the interaction between nanoparticles and substrate surfaces. Surface modification and fractionalization were employed to improve the dispersion of nanodiamond particles and separate those particles into a more narrow range of particle size. Mono-dispersed nanodiamonds with a ζ-potential and average particle size of -41.5mV and ~25.3nm, respectively, were then obtained. They can be charged on copper substrate without any contaminations. Two-dimensional self-assemblies of nanodiamond seeding were actualized. The density and homogeneity of nanodiamond particles which act as pre-existing sp 3 seeds shorten the incubation time of diamond nucleation to less than 30min. High quality of 750nm thick continuous diamond film was deposited on copper substrate in 60min. Furthermore, we calculated electrostatic interaction energy between nanodiamond particle and copper substrate by using the nonlinear Poisson-Boltzmann theory, and discussed interaction energy of nanodiamond-Cu substrate and nanodiamond-nanodiamond in the seeding process. © 2012 Elsevier B.V.
Chen W.,Changsha Institute of Mining Research |
Liu X.,Changsha Institute of Mining Research
Separation Technologies for Minerals, Coal, and Earth Resources | Year: 2012
In the iron ore of Yuanjiacun Mine, Taiyuan Iron and Steel (Group) Company Ltd (TlSCO), the main iron-bearing mineral is specularite, which features disseminated fine particle size distribution. In addition to quartz, the gangue minerals include a lot of refractory chlorite and amphibole. The influences of the slime on flotation time, reagent dosage and flotation results were investigated. The characteristics of selective separation of iron-bearing silicate minerals such as chlorite and amphibole from iron minerals were analyzed in detail. A practical process flow sheet was proposed for beneficiation of Yuanjiacun iron ore.
Chen W.,Changsha Institute of Mining Research
26th International Mineral Processing Congress, IMPC 2012: Innovative Processing for Sustainable Growth - Conference Proceedings | Year: 2012
The flotation efficiency of magnetic concentrate of the Anhui hematite ore, which includes a great quantity of iron-bearing silicates, has been studied through reverse flotation test with a new type of collector Fly-102. The results indicate that collector Fly-102 has a strong adaptability to the variation of temperature, when the flotation temperature is in the range of 10°C to 35°C, using collector Fly-102 can obtain good flotation indexes. Collector Fly-102 has a strong adaptability to the variation of the slime contents and grades of the flotation samples. When the content of slime and the grade of the flotation feeds are 30% and 55.63% respectively, under the condition that the temperature is 15°C, the open circuit flotation test was carried out with collector Fly-102. After one-stage roughing, one-stage cleaning and two-stage scavenging, a better result is got, the grade of iron concentrate reaches 67.12%, and the recovery of iron concentrate comes up to 84.15%.
He C.-S.,Changsha Institute of Mining Research
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2012
In this paper, to evaluate the cavability of ore rock comprehensively for guiding the block caving design, according to geological conditions exposed by engineering geological survey, the factors influencing the cavability of ore rock are studied by using multifactor comprehensive evaluation method. The results show that the comprehensive consideration on distribution law of the rock mass structure characteristics indexes can reflect the cavability of ore rock better. Finally, we classify the ore body cavability of one mining area in this paper, and find that the cavability of this mining area is between the levels of middle to better, which can provide an important guidance for the future work in mine.
Xing X.,Changsha Institute of Mining Research |
Ning S.,Changsha Institute of Mining Research |
She Z.,Changsha Institute of Mining Research |
Zhao Q.,Changsha Institute of Mining Research
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2013
The occurrence of vanadium in stone coal from Jiuquan, Gansu Province was studied through chemical analysis, phase analysis and valence analysis, etc. The relationship between vanadium's occurrence and leaching ratio was studied by direct acid leaching technology and blank roasting-acid leaching technique. On the basis of the confirmed occurrence of vanadium, combining the content analysis of vanadium content and impurities content analysis, the vanadium extraction technical process was ascertained. The results showed that most vanadium in the stone coal was almost completely located in mica mineral and ferric and aluminum oxides, and a few in difficult soluble silicate minerals and carbonaceous mineral, the proportion was respectively 64.44% and 27.78%, totally 92.22%. The leaching ratio of V2O5 was up to 90.2% by the crushing-blank roasting-dilute sulphuric acid leaching flowsheet, then the leaching agent was adsorbed by weak-base anion-exchange resin D301. After desorbed, the desorption solution was processed by dephosphorization and desilication purification-weak alkaline ammonium salt vanadium sink-calcined decomposition flowsheet. The powder product with 99.4% V2O5 was obtained. In the process, the adsorption rate was 98.5%, the desorption rate was 99.0%, the purification recovery was 98.2%, vanadium precipitation rate was 99.0%, the whole process V2O5 recovery was 85.5%.