International Journal of Minerals, Metallurgy and Materials

姓名
邮箱
手机号码
标题
留言内容
验证码

New influence factor inducing difficulty in selective flotation separation of Cu-Zn mixed sulfide minerals

Jiu-shuai Deng, Ying-bo Mao, Shu-ming Wen, Jian Liu, Yong-jun Xian, Qi-cheng Feng

2015, 22(2): 111-115. doi: 10.1007/s12613-015-1050-x

中文摘要(249) PDF(13) SpringerLink

摘要:
Selective flotation separation of Cu-Zn mixed sulfides has been proven to be difficult. Thus far, researchers have found no satisfactory way to separate Cu-Zn mixed sulfides by selective flotation, mainly because of the complex surface and interface interaction mechanisms in the flotation solution. Undesired activation occurs between copper ions and the sphalerite surfaces. In addition to recycled water and mineral dissolution, ancient fluids in the minerals are observed to be a new source of metal ions. In this study, significant amounts of ancient fluids were found to exist in Cu-Zn sulfide and gangue minerals, mostly as gas-liquid fluid inclusions. The concentration of copper ions released from the ancient fluids reached 1.02×10^-6 mol/L, whereas, in the cases of sphalerite and quartz, this concentration was 0.62×10^-6 mol/L and 0.44×10^-6 mol/L, respectively. As a result, the ancient fluid is a significant source of copper ions compared to mineral dissolution under the same experimental conditions, which promotes the unwanted activation of sphalerite. Therefore, the ancient fluid is considered to be a new factor that affects the selective flotation separation of Cu-Zn mixed sulfide ores.

Leaching of the residue from the dry off-gas de-dusting and desulfurization process of an iron ore sinter plant

Christof Lanzerstorfer, Qi Xu, Robert Neuhold

2015, 22(2): 116-121. doi: 10.1007/s12613-015-1051-9

中文摘要(312) PDF(10) SpringerLink

摘要:
The residue from a second-stage dry sinter plant off-gas cleaning process contains both the fine dust from the sinter plant and the sorbent used. Recycling of the material that is usually handled by landfills to the sinter plant feed is not possible because of its chloride content. Leaching of the chlorides allow the recycling of remaining solids. The saline leachate produced contains some heavy metals and must be treated before it is discharged into the sea. In laboratory experiments, leaching tests with the subsequent treatment of the leachate were conducted. After the process was optimized, all heavy-metal concentrations were below the permissible values. The optimum treatment conditions for heavy-metal precipitation were observed to be the filtration of the suspended solids followed by the dosing of liquid with lime milk (pH 10) and the subsequent precipitation using sodium sulfide.

Reduction process and zinc removal from composite briquettes composed of dust and sludge from a steel enterprise

Lei-ge Xia, Rui Mao, Jian-liang Zhang, Xiang-nan Xu, Meng-fang Wei, Fei-hua Yang

2015, 22(2): 122-131. doi: 10.1007/s12613-015-1052-8

中文摘要(326) PDF(11) SpringerLink

摘要:
In this study, composite briquettes were prepared using gravity dust and converter sludge as the main materials; these briquettes were subsequently reduced in a tube furnace at 1000-1300℃ for 5-30 min under a nitrogen atmosphere. The effects of reaction temperature, reaction time, and carbon content on the metallization and dezincification ratios of the composite briquettes were studied. The reduced composite briquettes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results show that the gravity dust and converter sludge are combined into the composite briquettes and a reasonable combination not only improves the performance of the composite briquettes, but also leads to the reduction with no or little reductant and flux. As the reaction temperature is increased and the reaction time is extended, the metallization and dezincification ratios of the composite briquettes increase gradually. When the composite briquettes are roasted at 1300℃ for 30 min, the metallization ratio and dezincification ratio reaches 91.35% and 99.25%, respectively, indicating that most of the iron oxide is reduced and the zinc is almost completely removed. The carbon content is observed to exert a lesser effect on the reduction process; as the C/O molar ratio increases, the metallization and dezincification ratios first increase and then decrease.

Development of carbon composite iron ore micropellets by using the microfines of iron ore and carbon-bearing materials in iron making

Jagannath Pal, Satadal Ghorai, Avimanyu Das

2015, 22(2): 132-140. doi: 10.1007/s12613-015-1053-7

中文摘要(322) PDF(15) SpringerLink

摘要:
Iron ore microfines and concentrate have very limited uses in sintering processes. They are used in pelletization; however, this process is cost intensive. Furthermore, the microfines of non-coking coal and other carbon-bearing materials, e.g., blast-furnace flue dust (BFD) and coke fines, are not used extensively in the metallurgical industry because of operational difficulties and handling problems. In the present work, to utilize these microfines, coal composite iron oxide micropellets (2-6 mm in size) were produced through an innovative technique in which lime and molasses were used as binding materials in the micropellets. The micropellets were subsequently treated with CO₂ or the industrial waste gas to induce the chemical bond formation. The results show that, at a very high carbon level of 22wt% (38wt% coal), the cold crushing strength and abrasion index of the micropellets are 2.5-3 kg/cm² and 5wt%-9wt%, respectively; these values indicate that the pellets are suitable for cold handling. The developed micropellets have strong potential as a heat source in smelting reduction in iron making and sintering to reduce coke breeze. The micropellets produced with BFD and coke fines (8wt%-12wt%) were used in iron ore sintering and were observed to reduce the coke breeze consumption by 3%-4%. The quality of the produced sinter was at par with that of the conventional blast-furnace sinter.

Effects of elemental Sn on the properties and inclusions of the free-cutting steel

Shao-chun Chen, Rong Zhu, Li-qiu Xue, Teng-chang Lin, Jing-she Li, Yang Lin

2015, 22(2): 141-148. doi: 10.1007/s12613-015-1054-6

中文摘要(379) PDF(17) SpringerLink

摘要:
A new environment-friendly free-cutting steel alloyed with elemental Sn (Y20Sn) was developed to meet the requirements of machinability and mechanical properties according to GB/T8731-1988. The machinability of the steel is enhanced by the segregation of elemental Sn at grain boundaries. The effect of Sn segregation on intergranular brittle fracture at normal cutting temperature from 250℃ to 400℃ is confirmed. The formation mechanism of main inclusions MnS is influenced by the presence of Sn and the attachment of Sn around MnS itself as a surfactant, and this mechanism also explains the improvement in machinability and mechanical properties of the steel. In the steel, the relevant inclusions are mainly spherical or axiolitic, and are uniformly distributed in small volume. Such inclusions improve the machinability of the steel and do not impair the mechanical properties as well. Experimental results demonstrate that the appropriate content of Sn in the steel is 0.03wt% to 0.08wt%, and the remaining composition is close to that of standard Y20 steel.

Corrosion behavior of the expandable tubular in formation water

Shu-jun Gao, Chao-fang Dong, An-qing Fu, Kui Xiao, Xiao-gang Li

2015, 22(2): 149-156. doi: 10.1007/s12613-015-1055-5

中文摘要(266) PDF(9) SpringerLink

摘要:
The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole environment after three months of application were also observed by stereology microscopy and scanning electron microscopy (SEM). The results show that, compared with the unexpanded sample, the area of ferrite increases dramatically after a 7.09% expansion. The expanded material shows a higher corrosion current in the polarization curve and a lower corrosion resistance in the electrochemical impedance spectroscopy (EIS) plot at every studied temperature. The determined critical pitting temperatures (CPT) before and after expansion are 87.5℃ and 79.2℃, respectively. SEM observations demonstrate stress corrosion cracks, and CO₂ corrosion and H₂S corrosion also occur in the downhole environment. Due to additional defects generated during the plastic deformation, the corrosion performance of the expanded tubing deteriorates.

Preparation of in situ and ex situ reinforced Fe-10Cr-1Cu-1Ni-1Mo-2C containing NbC particles by milling and hot pressing

Xiao-qiang Li, Zi-yang Li, Yong-quan Ye, Ke Hu

2015, 22(2): 157-166. doi: 10.1007/s12613-015-1056-4

中文摘要(343) PDF(19) SpringerLink

摘要:
An in situ and ex situ reinforced powder metallurgy (PM) steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass with the addition of NbC particles. A 40-h milling pretreatment makes the powder particles nearly equiaxed with an average diameter of ~8 μm, and the ferrite grain size is refined to ~6 nm. The sintered density reaches 99.0%-99.7% of the theoretical value when the sintering is conducted at temperatures greater than 1000℃ for 30 min. In the sintered bulk specimens, the formation of an in situ M₇C₃ (M=Cr, Fe, Mo) phase is confirmed. M₇C₃ carbides with several hundred nanometers in size are uniformly distributed in the matrix. Some ultra-fine second phases of 50-200 nm form around the ex situ NbC and in situ M₇C₃ particles. The sintered steel exhibits an excellent combination of hardness (> Hv 500) and compressive strength (2100-2420 MPa).

Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

Song-mei Li, Ying-dong Li, You Zhang, Jian-hua Liu, Mei Yu

2015, 22(2): 167-174. doi: 10.1007/s12613-015-1057-3

中文摘要(339) PDF(9) SpringerLink

摘要:
Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

Effect of alloying elements and processing parameters on the Portevin-Le Chatelier effect of Al-Mg alloys

Peng-cheng Ma, Di Zhang, Lin-zhong Zhuang, Ji-shan Zhang

2015, 22(2): 175-183. doi: 10.1007/s12613-015-1058-2

中文摘要(281) PDF(11) SpringerLink

摘要:
The effects of alloying elements and processing parameters on the mechanical properties and Portevin-Le Chatelier effect of Al-Mg alloys developed for inner auto body sheets were investigated in detail. Tensile testing was performed in various Zn and Mg contents under different annealing and cold-rolling conditions. In the results, the stress drop and reloading time of serrations increase with increasing plastic strain and exhibit a common linear relationship. The increase rates of stress drop and reloading time increase with increasing Mg or Zn content. The alloys with a greater intensity of serrated yielding generally exhibit a greater elongation. The stress drop and reloading time of serrations decrease with increasing grain size in the case of the annealed samples. The cold-rolled sample exhibits the most severe serration because it initially contains a large number of grain boundaries and dislocations.

Saturation phenomenon of Ce and Ti in the modification of Al-Zn-Si filler metal

Jin-long Yang, Song-bai Xue, Wei Dai, Peng Xue

2015, 22(2): 184-189. doi: 10.1007/s12613-015-1059-1

中文摘要(201) PDF(8) SpringerLink

摘要:
Cerium and titanium were added to an Al-42Zn-6.5Si brazing alloy, and the subsequent microstructures of the brazing alloy and the 6061 Al alloy brazing seam were investigated. The microstructures of filler metals and brazed joints were characterized by scanning electron microscopy and X-ray energy dispersion spectrometry. A new Ce-Ti phase formed around the silicon phase in the modified filler metal and this saturation phenomenon was analyzed. Interestingly, following brazing of the 6061 alloy, there is no evidence of the Ce-Ti phase in the brazing seam. Because of the mutual solubility of the brazing alloy and base metal, the quantity of the solvent increases, and the solute Ce and Ti atoms assume an undersaturated state.

Manufacturing process and microstructure of copper-coated aluminum wires

Xiao-hua Chen, Xin Tang, Zi-dong Wang, Xi-dong Hui, Mo Li, Yong-wei Wang

2015, 22(2): 190-196. doi: 10.1007/s12613-015-1060-8

中文摘要(252) PDF(7) SpringerLink

摘要:
Copper-coated aluminum wires exhibit good electrical conductivity, high thermal conductivity, low contact resistance of copper and low density, and provide economic advantages over aluminum. However, there are some problems in the manufacturing processes of hot-dip copper-coated aluminum wires, such as the difficulties in controlling coating process. In this work, the hot-dip copper-coating method of aluminum wires was investigated for producing copper-coated aluminum wire composites. The interface microstructure between the aluminum wire and the copper coating layer was analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). Five different fluxing agents were tested. Experimental results show that appropriate conditions for the hot-dip process are determined as the liquid copper temperature of 1085℃ and the treatment time less than 1 s. A success in hot-dip copper-coated aluminum wires is achieved by hot-dipping a low-melting-point metal into a high-melting-point metal liquid, which is significant for the further development and application of copper-coated aluminum wire composites.

Structural and optical analysis of Cr₂N thin films prepared by DC magnetron sputtering

Shakil Khan, A. Mahmood, A. Shah, Qaiser Raza, Muhammad Asim Rasheed, Ishaq Ahmad

2015, 22(2): 197-202. doi: 10.1007/s12613-015-1061-7

中文摘要(362) PDF(10) SpringerLink

摘要:
Chromium nitride (Cr₂N) thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300℃, and its influence on the film structure and refractive index was investigated. X-ray diffraction analysis shows that the crystalline structure of the films transforms from the (101) to (002) oriented hexagonal Cr₂N phase as the increase of substrate temperature above 50℃, and a highly textured film grows at 100℃. An empirical relation between the crystalline orientation and infrared active modes of the films is obtained, i.e., the Fourier transform infrared (FTIR) spectrum of the film prepared at 50℃ exhibits only A₁(TO) mode. The prominent peak in the FTIR spectra of the film prepared above 50℃ is assigned to the E₁(TO) mode and is correlated with the (002) or c-axis oriented hexagonal wurtzite phase of Cr₂N. In the surface analysis of atomic force microscopy, a transformation from the featureless surface to columnar-type morphology is observed with the increase of substrate temperature from 50 to 100℃, exhibiting c-axis oriented crystallite growth. A further increase in substrate temperature to 200℃ causes the c-axis crystallites to merge, resulting in the formation of voids. The refractive index (n) of the deposited films is obtained using spectroscopic ellipsometry.

Modified disordered carbon prepared from 3,4,9,10-perylenetetracarboxylic dianhydride as an anode material for Li-ion batteries

Fei-biao Chen, Bo-rong Wu, Yun-kui Xiong, Wei-lin Liao, Dao-Bin Mu, Feng Wu

2015, 22(2): 203-209. doi: 10.1007/s12613-015-1062-6

中文摘要(286) PDF(7) SpringerLink

摘要:
To prepare an anode material for Li-ion batteries with high discharge capacity and good cycling stability, disordered carbon (DC) formed by calcinations of 3,4,9,10-perylenetetracarboxylic dianhydride was modified via an acid treatment using a mixture of HNO₃ and H₂SO₄. The modified disordered carbon (MDC) was characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) analysis, and scanning electron microscopy (SEM). FTIR spectra confirm the successful introduction of carbonyl groups onto the DC surface. Some pores appear in the columnar structure of MDC, as observed in SEM micrographs. Li⁺ ions intercalation/deintercalation is facilitated by the modified morphology. Electrochemical tests show that the MDC exhibits a significant improvement in discharge capacity and cycling stability. These results indicate that the MDC has strong potential for use as an anode material in Li-ion batteries.

Fabrication method and microstructural characteristics of coal-tar-pitch-based 2D carbon/carbon composites

Mohammad Esmaeeli, Hamed Khosravi, Alireza Mirhabibi

2015, 22(2): 210-216. doi: 10.1007/s12613-015-1063-5

中文摘要(319) PDF(9) SpringerLink

摘要:
The lignin-cellulosic texture of wood was used to produce two-dimensional (2D) carbon/carbon (C/C) composites using coal tar pitch. Ash content tests were conducted to select two samples among the different kinds of woods present in Iran, including walnut, white poplar, cherry, willow, buttonwood, apricots, berry, and blue wood. Walnut and white poplar with ash contents of 1.994wt% and 0.351wt%, respectively, were selected. The behavior of these woods during pyrolysis was investigated by differential thermal analysis (DTA) and thermo gravimetric (TG) analysis. The bulk density and open porosity were measured after carbonization and densification. The microstructural characteristics of samples were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy. The results indicate that the density of both the walnut and white poplar is increased, and the open porosity is decreased with the increasing number of carbonization cycles. The XRD patterns of the wood charcoal change gradually with increasing pyrolysis temperature, possibly as a result of the ultra-structural changes in the charcoal or the presence of carbonized coal tar pitch in the composite's body.

留言板

2015年第22卷第2期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

留言板

2015年 第22卷 第2期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

2015年第22卷第2期