Effect of Na_2CO_3 on reduction and melting separation of ludwigite/coal composite pellet and property of boron-rich slag

The effects of Na_2CO_3 on the reduction and melting separation behavior of ludwigite/coal composite pellet, the desulfurization ratio and the property of the separated boron-rich slag were investigated at laboratory scale in the present work. Na_2CO_3 could improve the reduction rate of the composite pellet to some extent. The melting separation of the composite pellet became increasingly difficult with the increase of Na_2CO_3 in the pellet due to the sharply increasing of the melting point of slag. The sulfur content of the iron nugget gradually decreased from 0.27% to 0.084%（mass fraction） with the Na_2CO_3 content in the pellet increasing from 0 to 6%. The efficiency of extraction of boron（EEB） of the slow cooled boron-rich slag decreased from 86.46% to 59.52% synchronously. Na_2CO_3 had obviously negative effect on melting separation of the composite pellet and boron extraction of the boron-rich slag.

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial direction.The results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was expanded.When the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting amount.The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power.The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested.When the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch distance.When the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch distance.The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio.Through this study,the decoupling mechanism and ability of this innovative arc heat source is more clearly.

New process for treating boron-bearing iron ore by flash reduction coupled with magnetic separation

Boron is an important industrial raw material often sourced from minerals containing different compounds that cocrystallize,which makes it difficult to separate the mineral phases through conventional beneficiation.This study proposed a new treatment called flash reduction-melting separation(FRMS)for boron-bearing iron concentrates.In this method,the concentrates were first flash-reduced at the temperature under which the particles melt,and the slag and the reduced iron phases disengaged at the particle scale.Good reduc-tion and melting effects were achieved above 1550℃.The B_(2)O_(3) content in the separated slag was over 18wt%,and the B content in the iron was less than 0.03wt%.The proposed FRMS method was tested to investigate the effects of factors such as ore particle size and tem-perature on the reduction and melting steps with and without pre-reducing the raw concentrate.The mineral phase transformation and morphology evolution in the ore particles during FRMS were also comprehensively analyzed.

Mechanism of pool separation and stratification in laser remelting and cladding

The laser remelting with a two-layer material system (upper material was Al-30 % Ti-20 % Ni alloy,substrate was commercial aluminum alloy) and the laser cladding of a commercial 45 steel with copper Powder (including 25%SiC) were carried out using a 2kW continuous CO2 laser. For the case of laser remelting, a upper Pool in the alloying layer and a lower Pool in the substrate separated by the unmelted Al-Ti-Ni alloy were observed. For laser cladding, a stratified Pool was observed, whose top layer was Cu alloy liquid and bottom was Fe alloy liquid. The mechanism of laser Pool separation and stratification is illustrated by numerical calculation of heat transter process of the two-layer system, combining with material physical properties (especially mixed enthalpy). A classification criterion for laser Pool with the two-layer material system has been presented and four types of the laser Pool are divided into unique Pool, separated Pool, mixed Pool and stratified pool,which provides a theoretical basis for obtaining a excellent surface coating.

Effects of melt viscosity on enrichment and separation of primary silicon from Al-Si melt

The effects of melt viscosity on the enrichment and separation of Si crystals from Al–Si melt during an electromagnetic solidification process were investigated. Both the enrichment efficiency and the separation were found to be strongly dependent on the melt viscosity. A high melt viscosity was beneficial to the enrichment of primary silicon, whereas a low melt viscosity facilitated the separation process. A new enrichment mechanism was proposed in order to clarify the influence of melt viscosity, and an improved process for achieving high-efficiency enrichment of Si crystals via control of the melt viscosity was also proposed. Additionally, the morphology of Si crystals was found to change from spheroidal to plate-like in shape owing to the difference in viscosities in different regions.

Removal of phosphorus-rich phase from high-phosphorous iron ore by melt separation at 1573 K in a super-gravity field

A new approach of removing the phosphorus-rich phase from high-phosphorous iron ore by melt separation at 1573 K in a super-gravity field was investigated. The iron？slag separation by super-gravity resulted in phosphorus being effectively removed from the iron-rich phase and concentrated as a phosphorus-rich phase at a temperature below the melting point of iron. The samples obtained by super-gravity exhibited obvious layered structures. All the iron grains concentrated at the bottom of the sample along the super-gravity direction, whereas the molten slag concentrated in the upper part of the sample along the opposite direction. Meanwhile, fine apatite crystals collided and grew into larger crystals and concentrated at the slag–iron interface. Consequently, in the case of centrifugation with a gravity coefficient of G = 900, the mass fractions of the slag phase and iron-rich phase were similar to their respective theoretical values. The mass fraction of MFe in the iron-rich phase was as high as 97.77wt% and that of P was decreased to 0.092wt%.

Separation efficiency of alumina particles in Al melt under high frequency magnetic field

The effects of separation time and magnetic induction intensity on the separation efficiency of alumina particles with diameters varying from 30 to 200 μm in aluminum melt were investigated. The experimental results show that the particle-accumulated layer is formed in the periphery of the solidified specimen when the diameter of the separated molten metal, the magnetic induction intensity and the separation time are 10 mm, 0.04 T and 1 s, respectively. When the separation time is 2 s, the particle-accumulated layer can be observed obviously and the separation efficiency is about 80%. There are few alumina particles in the inner of the solidified specimen when the separation time is 3 s. The separation efficiency higher than 85% can be achieved when the separation time is longer than 3 s. When the magnetic induction intensity is 0.06 T, the visible particle-accumulated layer can be formed in 1 s and the separation efficiency is higher than 95%. The experimental results were compared with the calculated results at last.

Continuous electromagnetic separation of inclusion from aluminum melt using alternating current

A novel scheme about the continuous electromagnetic purification of aluminum melt was put forward based on the utilization of a square separation pipe and a 50 Hz alternating current to produce electromagnetic force. It is experimentally found that with electrical current of 400 A/cm2, it takes only 10 s to remove 95% inclusion from aluminum melt. Comprehensive numerical simulations were carried out to investigate the dynamics mechanisms behind the process. The results show that the removal of inclusion is attributed to the cooperative effects of electromagnetic buoyancy and the secondary flow induced by the rotational electromagnetic force, and the removal efficient increases with the size of inclusion and the electrical current imposed. Theoretical predictions on the distribution and removal efficiency of inclusion were supported by the experiments.

Electromagnetic separation of primary iron-rich phases from aluminum-silicon melt

The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separation indicates that primary needle-like β phases are difficult to separate; while primary α iron-rich phases can be separated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully when the molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.

LIQUID SEPARATION OF TUNGSTEN-TIN-BEARING GRANITIC MELT AT 85℃ AND 150 MPa

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Effects of Ni addition on liquid phase separation and giant magnetoresistance of Cu-Co alloys

The effects of Ni addition on the liquid phase separation and giant magnetoresi stance (GMR) of Cu Co alloys were discussed. The results reveal that Ni additio n can partially restrain the liquid phase separation of Cu Co alloys, resultin g in a decrease of volume fraction for the Co rich particles separated from the liquid phase and in refined microstructures. The composition analyses indicate t hat Ni is dissolved in both the Co rich and the Cu rich phases, but Ni content in the Co rich phase is much higher than that in the Cu matrix. At the same ti me, Ni addition enhance the solubility between Cu and Co, especially Cu in Co s olid solution. Ni alloying into Cu Co alloys can fully prevent the liquid phase separation during melt spinning, which is very beneficial to improve GMR of Cu Co alloys.

Multi-index analysis of the melting process of laterite metallized pellet

Herein, a multi-index analysis of the nickel content of an alloy, output rate of the alloy, nickel recovery rate, and iron recovery rate during the melting of laterite metallized pellets was performed. The thermodynamic reduction behavior of oxides such as NiO, FeO, Fe_3 O_4, and Cr_2 O_3 was studied using the FactSage software, which revealed that SiO_2 is not conducive to the reduction of iron oxides, whereas the addition of basic oxides such as CaO and MgO is beneficial for the reduction of iron oxides. On the basis of a comprehensive analysis to achieve greater nickel recovery and lower iron recovery rates, the optimum experimental parameters in the orthogonal experiment were A3 B1 C3(t = 30 min, C/O = 0.4, R = 1.2); the indicators wNi, φalloy, ηNi, and ηFe had values of 15.0 wt%, 12.1%, 44.9%, and 96.4%, respectively. In single-factor experiments, increasing basicity(R) substantially improved the separation effect in the low-basicity range 0.5 ≤ R ≤ 0.8 but not in the high-basicity range 0.8 ≤ R ≤ 1.2. Similar results were obtained for the effect of the C/O ratio. Moreover, the recovery rate of nickel increased with increasing recovery rate of iron.

Liquid phase separation of Cu-Cr alloys during rapid cooling

The ribbons of Cu-Cr alloys with high Cr content (15%- 35%, mass fraction) were prepared by rapid solidification. The microstructures of solidified samples were analyzed by scanning electron microscopy and transmission electron microscopy. The results reveal that a representative liquid phase separation microstructures are observed in Cu75Cr25 ribbons solidified at a cooling rate of about 104K/s. The liquid phase separation is not restrained when the cooling rate is enhanced to about 107K/s. However, the size of Cr particles solidified from Cr-rich liquid or Cr-rich regions in alloy melts could be refined by increasing the cooling rates. The size of Cr particles increases with increasing Cr contents when the ribbons contain 15% to 35%Cr.

Isotope hydrograph separation in alpine catchments:a review

Isotope hydrograph separation （IHS） is a basic tool in applied hydrology. Its application has expanded to surface water and groundwater interaction, and eco-hydrological processes from runoff generation processes. This paper reviews the progress made in IHS for alpine catchments, with emphasis on its significance in reflecting the impact of global change on water resources. Also, the principle of IHS and its uncertainties are explained in detail. The mechanism of variation of stable isotopes in snow-melt water is discussed, and then methods are presented to improve the separation during snow-melt such as volume weighted average method （VWA）, current melt-water method （CMW） and runoff-corrected event water approach （RunCE）, with their advantages and disadvantages explained. New approaches may extend the applications of IllS, for example, large basin studies combined with GIS, and develop new theories of runoff generation combined with other pararneters such as deuterium excess and DOC.

吉林红旗岭晚三叠世镁铁超镁铁质侵入体矿物化学和岩石地球化学特征:对镍铜成矿的启示

吉林红旗岭镁铁超镁铁质侵入岩群位于中亚造山带东段南缘,由3个北西向岩带(I、II、III)组成,包括30多个小岩株,其中I-岩带的部分岩体伴有铜镍矿化,并且其1和7号岩体分别形成了中型和大型岩浆铜镍硫化物型矿床。矿床主要容矿岩石为辉橄岩、橄辉岩、斜方辉石岩、二辉石岩、苏长岩和辉长岩。主量元素方面,红旗岭岩群具有富镁(w(MgO)=20.7%~31.1%)、低钛(w(TiO_(2))=0.33%~0.79%)、低碱(w(K 2 O+Na 2 O)=0.60%~2.29%)和硅(w(SiO_(2))=40.0%~53.0%)变化范围大的特征;微量元素方面,红旗岭岩群呈现弱富集LREE和LILE(Th)以及亏损HREE和HFSE(Nb-Ta-Ti)。岩相学、地球化学和矿物(橄榄石、斜方辉石、单斜辉石、尖晶石、斜长石和角闪石)主微量元素特征表明,红旗岭岩群明显不同于洋岛型玄武岩、阿拉斯加型环状杂岩和科马提岩,但与岛弧玄武岩以及中亚造山带西段的“黄山西”和“黄山东”铜镍硫化物矿床的容矿超镁铁质岩相似,其母岩浆是一种富Mg、亏损Nb-Ta的岛弧拉斑玄武质熔体,形成于晚三叠世古亚洲洋闭合后伸展环境,演化过程中经历了地壳混染和分离结晶作用,含矿母岩浆可能经历了硫化物的“二次熔离”,最终形成了铂族元素(PGE)亏损型岩浆铜镍硫化物矿床。

铁浴条件下电炉粉尘球团的熔融与分离行为

为了提高对含锌电弧炉粉尘(EAFD)的利用效率,实验研究EAFD球团在铁浴条件下的还原熔化行为。定义铁液滴球形度作为判断其凝聚的标准,然后探讨铁液滴直径和球形度之间随时间变化的关系。根据实验最终建立EAFD颗粒的熔化和分离行为。结果表明,在铁浴条件下,EAFD球团的Zn去除率在5.0 min时达到99%以上,但在15.0 min时金属渣分离还没有完成。由于成分的波动,在EAFD球团中形成几个区域的液态渣,然后液态渣不断增加,直到球团完全熔化。球形度>65%、直径>500μm的Fe液滴的数量随着时间的推移而减少,大直径的Fe液滴先完成分离。渣铁分离过程如下:在布朗运动下Fe液滴在渣中形成,之后Fe液滴直径在马兰戈尼效应下增加,Fe液滴在渣中下降速度符合斯托克斯定律。

熔喷非织造材料制备及其应用研究进展

为了解熔喷非织造材料在制造工艺、结构设计和应用等方面的研究进展,文章介绍了聚乳酸、聚丙烯等常用高聚物原料的特性,分析了以其为原料所制备熔喷非织造材料的性能特点,总结了熔喷非织造材料在空气过滤、液体过滤、医用抗菌、智能电子纺织品等领域的应用现状,提出了未来熔喷非织造材料的发展方向,以期为熔喷非织造材料的研究提供一定参考,拓展熔喷非织造材料应用领域。

废盐无害化处理工艺研究

为了解决制备精四氯化锆过程中产出废盐的处理难题,根据废盐微观形貌分析结果,将废盐加水溶解,利用强酸性体系使废盐中的金属离子溶出进入溶液,通过采用不同搅拌方式、浸出时间、压滤方式以及浸出试剂等实验,研究金属元素的分配及迁移规律。通过实验室条件摸索试验、放大试验以及条件优化试验,使处理后废盐中锆平均收率大于80%,不同阶段废盐锆收率基本稳定,处理每吨废盐用水量在10 t以下,中和渣及水溶渣pH值达到国家《危险废物鉴别标准腐蚀性鉴别》(GB 5085.1-2007)标准要求。

废炭渣协同二次铁铝渣无害化处理

企业通常采用湿法冶金工艺回收退役锂离子电池中的有价金属,在回收过程中产生废炭渣和二次铁铝渣,其中,二次铁铝渣因含有较多镍、铜等重金属,属于重金属固废,需对其进行无害化处理。基于“以废治废”的理念,本研究提出将二次铁铝渣和废炭渣协同处置,经脱硫、还原焙烧和熔融分离回收有价金属。结果表明,随着焙烧温度提高及脱硫时间延长,二次铁铝渣中剩余硫含量均逐渐减少、脱硫率均逐渐提高。当焙烧温度为1300℃、反应时间为2.5 h时,渣中剩余硫含量为0.068%、脱硫率为99.31%;经还原焙烧、熔融分离后,镍、钴、铜、铁的回收率分别为69.43%、74.52%、79.05%、79.29%;对熔渣进行浸出毒性检测,得到浸出液中铜、镍含量分别为0.013、0.984 mg/L,远低于GB 5085.3—2007限定值,实现了对熔渣的无害化处理。

Anodic process on Cu-Al alloy in KF-AlF3-Al2O3 melts and suspensions

Anodic processes on Cu-10 Al electrode in molten KF-AlF3-Al2O3(saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio(CR= x(KF)/x(AlF3)), temperature and particle volume fraction(φ) on the electrochemical behaviour of the anode were demonstrated. Initially, the anode was polarised in the galvanostatic mode in melt and suspensions(φ=0.12, 0.15) at 750 ℃ with 0.4 A/cm^2 current density. The anode potential in melt varied between 2.5 and 3.2 V and in suspensions(φ= 0.12) between 3.3 and 3.4 V. XRD analysis was conducted to study the oxide phases on the anode surface. Anode limiting current densities and mass transfer coefficients drastically decreased with the increase of φ in the suspension. The results suggest that the Cu-10 Al electrode works better in suspensions with CR of 1.4 and particle volume fraction of 0.09 at 800 ℃.