Effect of pyrite content of feed and configuration of locked particles on rougher flotation of copper in low and high pyritic ore types

Misreported pyrite into copper concentrates dramatically declines copper grade and recovery. Copper flotation can be also more complicated if flotation feed comes from an elevated-pyritic copper ore. In this investigation, the effect of two different ore types(high pyritic and low pyritic feeds) was studied on rougher stage of industrial copper flotation circuit. Samples were taken from different streams and the structure of chalcopyrite within the pyrite and non-sulfide gangue minerals was examined in various size fractions for mentioned ore types. Results indicated that 72% and 56% of the total floated pyrite was transferred to concentrate in first four cells in the low and high pyritic feeds, respectively. Whereas, this proportion for floated SiO_2 in last ten cells was detected as 72% and 71%, respectively. A detailed interpretation of the effect of locked particles in different size fractions on rougher flotation cells is studied from industrial point of view.

Magnesite and talc origin in the sequence of geodynamic events in Veporicum, Inner Western Carpathians, Slovakia

This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.

Design and control of chemical compositions for high-performance austempered ductile iron

This paper presents the effects of chemical compositions of austempered ductile iron （ADI） on casting quality, heat treatment process parameters and mechanical properties of final products. Through experiment and production practice, the impacts of carbon equivalent on ADI and its mechanical properties have been studied. Proper content ranges for carbon and silicon have been obtained to avoid ADI casting shrinkage and graphite fioatation, as well as to achieve the optimal mechanical properties. According to the impact of silicon content on austenite phase transformation, the existing form of carbon in ADI has been analyzed, and also the formula and diagram showing the relationship between austenitizing temperature and carbon content in austenite have been deduced. The chemical composition range for high performance ADI and its control points have been recommended, to serve as a reference for production process.

Simulation of cooling channel rheocasting process of A356 aluminum alloy using three-phase volume averaging model

The cooling channel process is a rehocasting method by which the prematerial with globular microstructure can be produced to fit the thixocasting process.A three-phase model based on volume averaging approach is proposed to simulate the cooling channel process of A356 Aluminum alloy.The three phases are liquid,solid and air respectively and treated as separated and interacting continua,sharing a single pressure field.The mass,momentum,enthalpy transport equations for each phase are solved.The developed model can predict the evolution of liquid,solid and air fraction as well as the distribution of grain density and grain size.The effect of pouring temperature on the grain density,grain size and solid fraction is analyzed in detail.

Simulation on solidification of an Al-Ni alloy under electromagnetic stirring

The microstructure of AI-Ni alloy has a significant influence on its performance, while electromagnetic stirring is one of the most effective methods for control of solidification structure of AI alloy. To investigate the effect of electromagnetic stirring on the solidification of the ingot, the solidification of the Al-50Ni alloy in vacuum with electromagnetic stirring was described by numerical simulation in this paper; and a three dimensional mathematical model was established. The electromagnetic field was simulated by ANSYS software and the thermal-flow field was simulated by FLUENT software. The coupling between the electromagnetic field and the thermal-flow field was implemented by user-defined subroutines. It is found that the current intensity has significant influences on the fluid flow and the microstructure of the alloy. The simulation results agree well with the experimental results, and the optimum current intensity under the exprimental conditions is 80 A, while the frequency is 50 Hz.

Determination of Inorganic Antimony Species Conversions during Its Speciation Analysis in Soil Using Isotope Dilution Techniques

A new method was developed in this work to account for inorganic Sb species interconversion during soil sample preparation and subsequent separation steps. The Sb(III) and Sb(V) concentrations at each investigated step in the analytical procedure were determined using species specific spikes (121Sb(III) with 81.18% and 123Sb(V) with 74.04% enrichment). The spiking of these enriched isotopes species solutions was done separately before soil sample extraction and before HPLC separation. Simply by subtracting the final concentration of each species done by on-line isotope dilution (ID) from its concentration at different stages of the analytical procedure done by species specific ID, the influence of each step on species transformation can be estimated. After optimization, the extraction procedure for inorganic Sb species 6% Sb(III) (1.3 RSD, n = 3) and 43.2% Sb(V) (2.9% RSD, n = 3) as percent of total Sb were detected in the examined soil sample using online ID. Using the above described methodology we found that there was no reduction of Sb(V) to Sb(III) during sample preparation or species separation. While about 9.3% of extractable Sb (4.6% of total) was converted from Sb(III) to Sb(V) during the extraction step, no conversion during HPLC separation step was observed. By compensating for Sb(III) transformation during the sample preparation step;the extractable Sb(III) and Sb(V) as percent of total Sb yielded 10.6% and 38.7%, respectively.

Hot cracking susceptibility of AlSi7MgCu alloys and effects of alloying elements magnesium and copper

Hot cracking during solidification can be a serious problem in aluminium casting alloys under certain conditions.This feature is well known,but still insuffi ciently investigated in shape casting.This study gives a brief overview of the factors inf luencing hot cracking during shape casting.Five different AlSi7MgCu alloys with varying Mg and Cu contents were examined.Theoretical models,including the cracking susceptibility coeffi cient(CSC)from Clyne and Davies,were considered.Thermodynamic calculations(terminal freezing range,TFR)of the behavior of the solid fraction during solidif ication were compared to an experimentbased hot cracking indexing(HCI)method.Scanning electron microscopy(SEM)was used to compare the existing microstructure and precipitated thermodynamic phases using the software ThermoCalc Classic(TCC).Furthermore,SEM was used to investigate crack surfaces initiated by a dog-bone shaped mold during casting.A good correlation between theoretical models and the experimental hot cracking index method was observed.

Role of fragmentation in as-cast structure:numerical study and experimental validation

A volume average solidification model is extended to incorporate fragmentation as the source of equiaxed crystals during mixed columnar-equiaxed solidification. This study is to use this model to analyze the role of fragmentation in the formation of as-cast structure. Test simulations are made for the solidification of a model alloy(Sn-10wt.%Pb) with two different geometries. The first one is a 2D rectangular domain(50 × 60 mm^2) as cooled from the top boundary. Solidification starts unidirectionally as columnar structure from the top. The solute(Pb) enriched interdendritic melt is heavier than the bulk melt, and sinks downwards, hence leads to solutal convection. Fragmentation phenomenon occurs near the columnar tip front. The fragments are transported out of the columnar region, and they continue to grow and sink, and finally settle down and pile up at the bottom. The growing columnar structure from the top and pile-up of equiaxed crystals from the bottom finally lead to a mixed columnar-equiaxed structure, in turn leading to a columnar-to-equiaxed transition(CET). The second geometry is a 3D plate, 100 × 60 ×10 mm^3, as cooled laterally from one side. It was cast experimentally and analyzed for the as-cast structure. The equiaxed fragments are produced in the solidification front and transported into the bulk melt, leading to a special pattern of as-cast structure: columnar structure in the cool wall side and equiaxed structure in the upper left corner near the hot wall side, extending downwards to the middle bottom region. Numerically calculated as-cast structures agree with the experiment results.

等轴球晶凝固多相体系内热溶质对流、补缩流及晶粒运动的数值模拟 Ⅰ．三相流模型

基于Eulerian-Eulerian方法和体积元平均技术,建立了模拟等轴球晶凝固过程的液、固、气三相流模型．液、固两相处理成相互分离、相互扩散的介质,气相与液、固两相只存在热量及动量的相互作用,三相(凝固前)作为自由流体共享一个统一的压力场．分别求解三相的质量、动量、溶质、热焓守恒方程;相间的热量交换和摩擦拖拽以及液／固界面上的溶质再分配和凝固潜热释放,通过定义对应守恒方程的源项和交换项而加以考虑;另外,单独求解一个晶粒密度守恒方程．晶粒的形核生长(相变) 也加以模型化并体现在对应的源项中,模型中所用的密度定义为溶质与温度的函数,因此可综合考虑热溶质对流、晶粒运动及凝固收缩所引起的补缩流动．凝固过程的体积收缩及补缩流动将体现在气／液自由表面的波动上．

等轴球晶凝固多相体系内热溶质对流、补缩流及晶粒运动的数值模拟 Ⅱ．模型的应用

利用等轴球晶三相凝固模型模拟了A356铝合金半固态浆料冷却斜槽法制备过程,研究了晶粒密度、尺寸及固相分数的分布与工艺参数的关系．结果表明,在斜槽浇注处晶粒形核密度最大,在斜槽末端晶粒尺寸、固相分数最大,在铸型中这三者的最终分布大致均匀．适当降低浇注温度有助于提高斜槽上形核密度和固相分数及降低晶粒尺寸．此外,还模拟了热溶质对流及补缩流在Al-4％Cu(质量分数)合金等轴球晶凝固过程所起的作用,以及晶粒运动及补缩流对合金自由表面和宏观偏析形成的影响．结果表明,凝固初期热对流及补缩流为主导,凝固中期热溶质对流为主导,凝固后期补缩流为主导;晶粒运动受阻程度直接影响自由表面形状,补缩流考虑与否导致完全不同的宏观偏析图．实验测得晶粒尺寸与模拟结果分布较相似,但其绝对值存在较大差异．

斯洛伐克西喀尔巴阡山Koice-Medvedia菱镁矿床的矿物学、流体包裹体和碳-氧-锶同位素研究(英文)

Kosice矿床是斯洛伐克第二大的菱镁矿床(150Mt),位于Gemeric的东部.其镁质碳酸盐矿体赋存于石炭纪石灰石和含白云石的石灰石中,同时下盘黑色片岩中也含有被铁质碳酸盐交代的薄层碳酸盐透镜体.在华力西期造山运动(M1)中,古生代岩石受到了低级变质作用(绿泥石带).镁交代作用始于白云岩1的结晶作用,其后形成菱镁矿,最终沿裂隙形成铁菱镁矿.铁质碳酸盐包括早期铁白云石-白云石,铁白云石和后期含方解石和石英的菱铁矿.根据碳酸盐矿物对地质温度计,白云石l结晶作用发生在300～340℃.这一结果与M1的变质矿物组合(绿泥石,白云母-伊利石)吻合.铁白云石的结晶作用发生在320～370℃.少量细脉中可见白云石2,绿泥石和伊利石-多硅白云母,它们是由于阿尔卑斯期造山运动M2变质作用形成的更晚的矿物组合.菱镁矿的流体包裹体(FI)研究,显示存在不同成分的热卤水,卤水成分变化相当于NaCl含量21～42 wt%,但其它成分的盐含量高于NaCl,溶解的CO2含量也有变化.两相包裹体均一温度(Th)的范围为164～217℃,含石盐子晶包裹体均一温度的范围为217～344℃.富CO2包裹体(盐度相当于NaCl含量1～22wt%,CO2的密度为0.28～0.77 g·cm-3,均一温度为289～344℃)在菱镁矿中是次要的,但这种包裹体在与矿石伴生的石英中是主要的,并且与含石盐子晶流体包裹体共生.在后期镁交代过程中流体中的CO2逐渐增加.和铁质碳酸盐伴生的石英中只有两相包裹体,包裹体中CO2含量有所变化,盐度范围为17～24 wt%的NaCl(或者34～36 wt%的MgCl2),均一温度为152～195℃.包裹体的数据结合碳酸盐地质温度计显示镁交代作用的压力范围是180～320MPa(7～12km),铁交代作用的压力范围是280～420MPa(10～16km),说明地热梯度约为25～35℃/km.包裹体浸出液的分析表明Cl/Br和Na/Br的比值存在变化,但仍旧说明富镁的卤水来源是上二叠纪和下三叠纪的分馏蒸发岩来源.铁质碳酸盐流体的高溴和高碘含量,说明在铁交代过程中周围黑色片岩的明显影响.菱镁矿和铁交代作用,表明交代流体中的碳和二氧化碳,主要是海洋沉积的来源.菱铁矿的'Sr/86Sr比值((0.71124～0.71140),说明锶的多来源,最初应是石炭纪和二叠纪的海水,但它被当地其它陆壳中的锶混染.

斯洛伐克西喀尔巴阡山脉Gemerská Poloma滑石-菱镁矿矿床中镁的交代作用(英文)

Gemerska Poloma矿床是个重要的滑石矿床(储量20万吨),位于西喀尔巴阡山脉Germeric地区.部分滑石化的镁质碳酸盐体赋存在早古生代火山沉积杂岩体中(黑色片岩,变质泥岩),在Variscan变质作用(M1)过程中受到了绿泥石-黑云母带区域变质相的改造.这种原岩是石灰岩的矿体由白色-灰白或者灰色-黑色的菱镁矿与白云石1组成,被次生的白云石2和滑石脉切割.本次研究考察了两次变质事件(M1和M2)的几个连续的矿物组合,最早的组合包括铁白云石,镁菱铁矿与菱铁矿,(并与黑电气石,铁绿泥石,磷灰石,与伊利石-白云母伴生),它们以微小残留物形式产出在菱镁矿和白云石1中,其形成可能早于M1变质作用高峰期.M1变质事件的高峰期以富铁金云母,镁绿泥石1,镁电气石(黑电气石的边缘)和石英的组合为代表.在M1退变质作用过程中,发生了镁交代作用,开始是白云石1结晶,接下来形成菱镁矿,最后是以铁菱镁矿沿裂隙的形成而终.根据碳酸盐地质测温原理,M1变质事件的高峰期温度为460～490°C,变质矿物组合特征也支持这一测温结果.滑石,白云石2,与镁绿泥石2沿着镁碳酸盐岩石裂隙的发育,主要受到M2变质事件的影响,这个变质事件与较年青的Alpine造山事件有关.菱镁矿流体包裹体的研究表明,成矿流体具有复杂的组成,可能以MgCl2组分为主,主要来源于蒸发卤水的演化.原生流体包裹体的盐度～35(wt%MgCl2),均一温度变化范围是216～235℃.石英中流体包裹体也显示了以MgCl2组分为主的相似流体组成,但均一温度比较高,为248～313℃.如果假定石英与M1变质事件同期,那么由流体包裹体计算出的M1变质峰期压力范围是250～350MPa(9～13km),因此地温梯度是35～40℃/km.假定这个梯度在镁交代成矿过程中保持不变,那么相关流体在180～280MPa(7～11km)的压力下的温度为300～350℃.流体包裹体的淋滤分析表明,流体中Cl/Br与Na/Br都很高,说明流体具有蒸发特征.而在Gemeric地区只有在晚二叠纪到早三叠纪这段时间才有如此大量的卤水形成.因此,二叠纪的伸展构造运动与形成菱镁矿的热液系统的形成有关.

Numerical microstructure prediction for an aluminium casting and its experimental validation

Virtual manufacturing based on through-process modelling becomes an evolving research area which aims at integrating diverse simulation tools to realize computer-aided design, analysis, prototyping and manufacturing. Numerical prediction of the as-cast microstructure is an initial and critical step in the whole through- process modelling chain for engineering components. A commercial software package with the capability of calculating important microstructure features for aluminium alloys is used to simulate a G-AISi7MgCu0.5 laboratory casting. The simulated microstructure, namely grain size, secondary dendrite arm spacing and diverse phase fractions are verified experimentally. Correspondence and discrepancies are reported and discussed.

采用UV光诱导微孔发泡产生3D结构的胶印新方法

0引言近年来，科研人员研发出多种新型印刷技术和印刷油墨，以实现不同基底上制备凸起三维（3D）结构。本研究开发出一种基于光化学反应的新型发泡油墨，无须其他辅助工艺。

铸锭宏观组织和偏析的数值仿真（英文）

自1960s Flemings时代起人们经过半个世纪的努力已对铸锭内铸态组织和宏观偏析形成的物理机理有了定性或半定量的认识,但还是难以对其进行定量预测,主要原因是其与各种多相流现象有关,例如凝固糊状区枝晶间的对流,等轴晶区晶粒沉积等。当然这些多相流现象是与凝固过程热力学和扩散动力学以及宏观铸态组织形成过程相耦合的。近20年多相计算流体动力学的发展及其在凝固领域的应用为解决上述问题提供了有效手段。首先对这方面的进展作一个简要综述,通过具体事例重点展示其在铸锭铸态组织和宏观偏析形成过程动态数值仿真的应用前景,指出目前存在的某些局限性。

Experimental research on hot-tearing crack sensitivity

Hot-tearing cracks usually form near the solidus temperature. It is caused by a combination of tensile stress and metallurgical embrittlement. In order to quantify embrittlement and to incorporate it in the thermal-stress analysis, many different criteria have been developed. Among them,the submerged split-chill tensile （SSCT） test is an efficient one. This paper tries to use SSCT to estimate the critical strain of hot tearing for some steels.

Deformation history and processes during accretion of seamounts in subduction zones:The example of the Durkan Complex(Makran,SE Iran)

The Durkan Complex is a tectonic element of the Makran Accretionary Prism(SE Iran)that includes fragments of Late Cretaceous seamounts.In this paper,the results of map-to micro-scale structural studies of the western Durkan Complex are presented with the aim to describe its structural and tectonometamorphic evolution.The Durkan Complex consists of several tectonic units bordered by mainly NNW-striking thrusts.Three main deformation phases(D_(1),D_(2),and D_(3))are distinguished and likely occurred from the Late Cretaceous to the Miocene–Pliocene.D_(1) is characterized by sub-isoclinal to close and W-verging folds associated with an axial plane foliation and shear zone along the fold limbs.This phase records the accretion of fragments of the seamount within the Makran at blueschist facies metamorphic conditions(160–300℃ and 0.6–1.2 GPa).D_(2) is characterized by open to close folds with subhorizontal axial plane that likely developed during the exhumation of previously accreted seamount fragments.An upper Paleocene–Eocene siliciclastic succession unconformably sealed the D_(1) and D_(2) structures and is,in turn,deformed by W-verging thrust faults typical of D_(3).The latter likely testifies for a Miocene–Pliocene tectonic reworking of the accreted seamount fragments with the activation of out of sequence thrusts.Our results shed light on the mechanism of accretion of seamount materials in the accretionary prisms,suggesting that seamount slope successions favour the localization and propagation of the basal décollement.This study further confirms that the physiography of the subducting plates plays a significant role in the tectonic evolution of the subduction complexes.

On self-affine tiles that are homeomorphic to a ball

Let M be a 3×3 integer matrix which is expanding in the sense that each of its eigenvalues is greater than 1 in modulus and let D?Z^(3)be a digit set containing|det M|elements.Then the unique nonempty compact set T=T(M,D)defined by the set equation MT=T+D is called an integral self-affine tile if its interior is nonempty.If D is of the form D={0,v,...,(|det M|-1)v},we say that T has a collinear digit set.The present paper is devoted to the topology of integral self-affine tiles with collinear digit sets.In particular,we prove that a large class of these tiles is homeomorphic to a closed 3-dimensional ball.Moreover,we show that in this case,T carries a natural CW complex structure that is defined in terms of the intersections of T with its neighbors in the lattice tiling{T+z:z∈Z^(3)}induced by T.This CW complex structure is isomorphic to the CW complex defined by the truncated octahedron.

Recent status of fluidized bed technologies for producing iron input materials for steelmaking

Today steel is produced by two steelmaking processes, the basic oxygen furnace and the electric arc furnace, Three types of iron input materials for both processes are liquid hot metal or in solidified form as pig iron, direct reduced iron （DRI） and hot briquetted iron （HB1） as well as steel scrap. Hot metal, pig iron, DRI and HBI are virgin iron materials, which have to be produced from iron ore by the so-called ironmaking technologies. New ironmaking processes based on fluidized bed technology have been developed in the last two decades. The main advantage of these technologies is that fine ore can be directly used in the processes and prior treatment such as sintering or pelletizing can be avoided which is required for the established processes. Theoretical aspects for reduction of fine iron oxides in a fluidized bed reactor system will be explained. The fluidized bed reducing technologies utilized in the most advanced new ironmaking processes for direct use of fine ore, FINMET, Circored, FINEX~ and Hismelt will be compared.

Influence of the Earth Magnetic Field on Electrically Induced Flows

The present paper aims at numerical simulation of the intriguing experimental observations made by Bojarevics on the appearance of swirl in flows in an electrically induced flow.Although controlled by poloidal force,the flow rotates due to the presence of the earth magnetic field.The bulk flow rotates almost as a whole which indicates that the swirl is generated through a mechanism of 'poloidal suppression'.