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By Xiao Long, Ting Wu, Lilong Zhu, Qian Wang, Shengping He

"During the continuous casting of peritectic steel slabs, mould fluxes with high crystallization capacity are usually chosen for improving slab surface quality. However, the lubrication condition of casting shell also could be deteriorated. Since precipitation of crystals within liquid slag film can change the composition and property of liquid slag over solid-liquid slag film interface region, its impacts on continuous casting process also are not clear. In order to clear this phenomenon, an experiment method was put forward, and mould fluxes for peritectic steel slabs continuous casting were selected and examined. The results reveal that after crystals have been separated, the crystallization capacity of leftover liquid slag increased with different levels, which could deteriorate the lubrication condition of casting shell and cause a series of problems. Thereby, mould fluxes with high crystallization capacity at beginning for heat transfer control and then weaker after crystallization should be considered in the future.IntroductionIn the continuous casting of peritectic steel slabs, contradiction between heat transfer control and slab shell lubrication by mould fluxes has been treated as a key problem for maintaining a smooth manufacturing process [ 1]. Strong and uneven horizontal heat flux over the meniscus region will cause uneven solidification of casting shell, especially for peritectic steel slab with enormous volume change caused by phase transition. All of those could cause surface defects like longitudinal crack [2-4]."

Jan 1, 2013

By Lv Guozhi, Niu Liping, Shi Guanyong, Liu Yan, He Jicheng, Du Yanjun, Dou Zhihe

"We proposed thermit reduction-electroslag remelting method of preparing the large scale CuCr alloy. But there are pores and oxide inclusions in CuCr alloy prepared by thermit reduction process. This paper studied mainly the effects of ratio of reactant and additive on the inclusion type and their occurrences in CuCr alloy. The alloy prepared in different process conditions was characterized via XRD, SEM, OM and TEM and metallographic microscope, in which the existing state and micro-structural defects of inclusions are analyzed. The results show that there are three distinct regions: copper-rich regions, chromium-rich regions and the inclusion regions. Inclusions are mainly in the form of stomata and Alz03 phase, mainly locating in the copper-rich phase and the interface area of chromium-rich phase and the copper-rich phase. Adding Na3AlF6 and heating agent can effectively reduce the inclusion content in the alloy.1 IntroductionIn recent years, with the development ofhigh power vacuum and high-pressure technology ,the CuCr alloy contact material which has many advantages gradually replaced the traditional W-Cu and Cu-Bi series alloy contact material, and become the first choice of material in high-voltage and high-power vacuum switch contacts['-3l. The traditional powder metallurgy method, infiltration method and vacuum arc melting method[4-SJ are using metal Cu powder and Cr powder as raw material by casting molding, and have disadvantages such as high production costs, complicated process, poor product density and low yield, especially in the large size alloy ingots[9-12l. At present, the world regards CuCr alloy new preparation technologies as the first place, and how to achieve a large size the CuCr alloy ingot preparation has become a hot research of CuCr alloy[3l. Zhang Ting-an and Dou Zhihe[l-3l who are supported by national natural science fundation of china successfully successful developed new technologies and core equipment to prepare large-size copper-chromium alloy through aluminum thermal reduction-secondary refining method, and obtained two national invention patents. The method includes two key steps: one is get CuCr alloy consumable ingot by Thermit-SHS with electromagnetic stirring, the other is to refme the CuCr alloy ingot to remove the pores, inclusions and other defects by electroslag remelting technology to get dense and uniform CuCr contact material. The preliminary study results show that means of electromagnetic stirring evidently inhibit effect of alloy ingot macrosegregation during the electromagnetic casting stage, but there are still microstructure defects such as alumina inclusions and pores in the alloy ingots. Therefore, Zhang Ting-an et al refer new ideas of using the electroslag remelting to refine Cu Cr alloy ingots and effectively remove the defects of the ingots such as pores and inclusions [3l _ At present, there is no report of study on the electroslag remelting refining processes of CuCr alloy (the refining slag, remelting current). This article will research mode of occurrence and distribution law of inclusions in the large-size CuCr alloy ingots by Al Thermit-SHS under magnetic field stirring action and provide a theoretical basis for chosing refining slag to remove inclusions by electroslag refining. Meanwhile the article analyses the effect of reduction conditions of Thermit-SHS on the types of inclusions, mode of occurrence and distribution of regular inclusions in alloy ingot, and refer theory for inclusions regulation in the large-size alloy ingots."

Jan 1, 2013

By Donghai Li, Cheng Pan, Pan Chen, Xuewei Lv, Mei Liu

"Chromite concentrate after beneficiation can not be directly used in the electric furnace. Therefore sintering is one of the effective way to agglomeration, by which the chromite concentrate can be utilized and the power cost of ferrochrome smelting can be reduced. The properties of raw materials and the sintering process of chromite concentrate were studied in this work. The results showed that chromite concentrate used can hardly granulated alone, while chlorite addition can improve the effect of granulation. Moisture plays an important role in sintering process. The granulation effect is optimal when the amount of water addition is 12%. Strength and abrasion index are the evaluation indexes of sinter quality. It was found that the strength of sinter increased with coke dosage increasing to 12%, and then decreased when it continuously increased. Opposite regularities were found for the abrasion index of the sinter.1 IntroductionChromium is a very important metal element which is mostly used in the production of stainless steel. In the earth, it is always formed compound with iron as ferrochromium spinel (FeO.Cr203), and its mineralogical name is chromite.[1] Currently, the global production of chrome ore is about 20 million tonnage every year , in which fine ore (less than 8 mm) accounted for about 80% [2] Although the price of the fine ore is cheaper than the lump one, too much fines will lead to the poor permeability and causes increased electricity consumption while producing ferrochrome. Therefore, the agglomeration process of chrome ore is one of the effective measures to increase the usage ratio of fine ore."

Jan 1, 2013

By A. R. G. Azevedo, G. C. Xavier

"The search for technological innovations in the Civil Construction takes as an objective the reduction of costs and increase of the productivity. However, these technologies demand analysis and studies of parameters of control that provide the quality of the products. With the intention of improve the knowledge on industrialized mortars used in mechanized projection machines, a characterization was done in the state anidro, fresh and hardening of three mortars, being each one of a State, Rio de Janeiro, Sao Paulo and Bahia. The tenors of water/ mortar was obtained through tests done in built environment, it varied from 0,17 to 0,26. From these results, the mortars were projected by his respective consistency, analyzing its compressive strength, and traction adherence resistance, in this way, the good performance of the revetments was provided.IntroductionThe market competitiveness of Construction has led companies to invest in construction processes and techniques in order to rationalize and optimize the buildings. Thus, changes emerged in coating system providing improvements in conventional materials and novel construction techniques, such as mortar industrialized and mechanized projection.Adopting projection equipment mortar is flagged as one of the solutions to reduce the interference of hand labor in construction, optimizing the performance of internal and external coatings, as well as streamline the production process and transportation, reducing lossesMaterials and deadline for execution of the casing(l)The process has been used due to its benefits, however, studies are necessary parameters for quality control of these mortars used in the projection to greater knowledge of mixing and market acceptance. It is therefore quite relevant information processing techniques available on the subject, as necessary to carry out research aiming at defining specific indicators of quality."

Jan 1, 2013

By Onuralp Yücel, Mehmet Bugdayc, Murat Alkan

"In this study, iron based alloys (Fe-Mo, Fe-Cr-Ni, etc.) were produced by using aluminothermic methods starting from Mill Scales obtained continuous casting processes. Mill scales are an oxidised layer of steel alloys containing iron oxide, which includes + 2, + 3 values, on the surface of slabs and billets occurring during annealing in heating furnace at integrated iron and steel milling plant, and continuous casting unit. In the metallothermic experiments, different ratios of starting mixtures and addition of the oxide powders (Alz03, Si02, CaO, MgO) were examined, and their effects on the metal recovery and alloy compositions were carried out. The samples were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis process (SHS) has many favour compared to the furnace applications, such as low energy requirement, low cost, very short processing time and simple operation, [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. Mill scale is a layer of iron oxide which forms on ferrous materials cooling after being processed in hot rolling or continuous casting plants. Mill scale contains iron (II) and iron (III) oxides, which result in a 70% total iron content in oxide form. Not being able to reuse this material will prevent the raw material entering the production plant from being fully utilized [5]. This study aimed to produce Fe-based alloys via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys by using high metallic iron content by reducing continuous casting mill scale."

Jan 1, 2013

By Hessam Yazdani

In comparison to the conventional piled foundations, the piled-raft foundations provide a more economical solution to support high-rise buildings constructed on soft soils. In this type of foundations, the bearing capacity of the underlying soil is taken into account to support the superstructure loads and the piles are placed to control both the total and differential settlements of the superstructure. Currently, there is not a standard and worldwide acceptable approach to select the location of the piles and most of piled-raft foundations are designed based on the experience of designers. Therefore, particular attention should be given to the optimal design of this type of foundations in order to minimize the considerable construction costs involved. This paper examines the capability of the ant colony optimization (ACO) algorithm to optimize the piled-raft foundations subjected to static and seismic loadings. The soil-pile interaction is considered by modeling the side and tip resistance components of the piles using the nonlinear Winkler-based p-y and t-z curves in the OpenSees program. The soil-raft interaction is taken into consideration using the Winkler springs beneath the raft. The objective of the optimization problem is to minimize the construction cost of the foundation by taking the configuration and number of the piles as design variables. The side and tip forces of the piles as well as the total and differential settlements of the foundation under the serviceability limit state are considered as the constraints for the optimization problem. Results show that in addition to the type of analysis (linear/nonlinear), the regard or disregard of the soil-pile interaction in the analysis can significantly change the optimal solution. The optimal solutions obtained match the engineering expectations and indicate the effectiveness and capability of the ACO algorithm to minimize the construction cost.

Jan 1, 2013

By K. Viking

This article deals with some of the civil engineering related problems to be encountered when offshore wind energy projects transform from prototype offshore wind energy converter farms, developed and installed during the 1990?s, to commercial farms that?s currently planned to be built. The offshore wind energy converter (OWEC) installations encounter a wide range of problems, only partial of these are geotechnical. In Europe both onshore and offshore wind farms have, from a historical point of view, usually been founded by using the monopole technique, installed with traditional impact hammers, or by using gravitational foundations. However, the rapid development of bigger turbines and larger wind farms, together with increasing considerations of fatigue aspects, has lead to financial benefits of developing and exploring other foundation techniques. This paper reviews some Scandinavian experiences regarding critical components of the design phase in relation to connecting the superstructure to the ground, and some of the main considerations of how the loads applied to the structure are transferred to the surrounding soil.

Jan 1, 2013

By Minjun Tang, Jianfeng Zhou, Linjiang Qing, Yufeng Guo, Tao Jiang

"For the comprehensive recovery ofV, Ti, Fe in vanadium-titanium magnetite in the process of pre-reduction-electric furnace smelting, it is expected that vanadium oxide is reduced into molten iron and titanium oxide is available in the slag. Thus the effect of slag basicity, the content of MgO, MnO and CaF 2 of slag content on the separation of slag and molten iron and the comprehensive recovery of V, Ti, Fe were investigated. The results show that increasing slag basicity, MgO, MnO and CaF2 are all beneficial to the separation of slag and molten iron. Higher slag basicity and the addition of CaF2 strengthen the reduction of vanadium oxide, and inhibite the reduction of titanium oxide, which are in favour of the recovery ofV and Ti. However, the addition ofMgO, MnO was not efficient for the comprehensive recovery ofV, Ti, Fe. For the vanadium-titanium magnetite of Panxi in China, the recovery of Fe was over 98%, the recovery ofV in molten iron was over 85% and the Ti02 content in slag was about 43% under the optimal conditions of slag phase type.IntroductionIt is well known that there are abundant vanadium-titanium magnetite resources which are located in Panzhihua of Sichuan Province[!]. At present the vananium-titanium magnetite concentrates are smelted in the blast furnace, which just make use of iron and vanadium, but lots of titanium is discarded in the slag. At the same time, the process has a large number of disadvantages, such as low recovery of vanadium, long route, pollutions, large investment and expenditure of energy[2-3]. In recent years, in order to efficiently utilize the vanadium-titanium magnetite concentrates, several new non-blast furnace processes have been proposed, such as pre-reduction-electric furnace, pre-reduction-grinding separation and so on[4]. Especially pre-reduction-electric furnace is operating well in South Africa and New Zealand,However,Du to the high slag basicity of the slag, the grade ofTi02 of slag is Corresponding author:Minjun Tang.E-mail:450435123@qq.com. Tel:13627429224."

Jan 1, 2013

By Baojun Zhao, Zhixiang Cui, Zhi Wang

"Bottom blown oxygen copper smelting process has been developed in Dongying, China by Dongying Fangyuan Nonferrous Metals Co., Ltd. in commercial scale. This is the first modem copper smelting technology developed in China with the advantages of high oxygen enrichment, low temperature and autothermal operation. Production capacity of more than 100,000 tonnes per year of copper has been achieved through a single bottom blown oxygen furnace with instantaneous feed rates reaching up to 90 t/h. The main features of the bottom blowing smelting process are that high grade matte (up to 72 wt% Cu) can be produced at relatively low temperatures with 2-3 wt% Cu remaining in the smelting slag. Analyses of quenched smelting slag show that significant amount of magnetite crystals are present in the slags at operating temperature which indicates that the operating temperature was much lower than the liquidus temperature of the slag. After four years operation this new technology has shown great potential for expanding production capability and energy saving. Process development continues on the first commercial scale bottom blown furnace at Dongying Fangyuan Nonferrous Metals and a larger bottom blown smelting furnace is under construction.IntroductionFlash and bath smelting technologies are the major processes used in modem copper making industry [l]. Ausmelt/Isasmelt using top blown and Noranda/Teniente using side blown are typical and common bath smelting technologies. In 1980s-1990s Hunan Shuikoshan Mineral Bureau, jointly with China Nonferrous Engineering and Research Institute (now China Enfi Engineering Corp.), developed the concepts of the bottom blown oxygen processes for both lead and copper smelting [2]. After the pilot test on 3000 ton copper per year scale in 1991, it was not progressed to industrial scope."

Jan 1, 2013

By Kain Petterson, P D. Katsabanis

Blast fragmentation, determined using image analysis was correlated to drill monitoring parameters in an open pit operation. Average fragment size and 80% passing size showed strong correlation with specific energy of drilling as well as with torque, while the same passing sizes did not correlate well with the rate of penetration. It was also determined that the uniformity of fragmentation decreases with the specific energy of drilling. Thus drilling monitoring parameters appear to be valuable in determining the blastability of the rock mass, enabling adjustment of blast loading to respond to changing conditions in the rock mass.

Jan 1, 2013

By S. R. Amos, N. O. Lotter, A. L. Hannaford, J. F. Oliveira, D. W. Broughton

"Ivanplats Ltd appointed Xstrata Process Support to perform the flowsheeting development work for their hypogene and supergene geomet units of the Kamoa Copper deposit, located in the Democratic Republic of the Congo. Through systematic flowsheet development using modern Process Mineralogy, the optimised milestone flowsheet delivered a saleable concentrate grade of 32.8% Cu at 85.4% recovery with hypogene ore, and a saleable concentrate grade of 45.1% Cu at a recovery of 83.4% for supergene ore. The significant value of this development is that a single flowsheet will treat both hypogene and supergene ores and produce saleable concentrates. Further work to advance the flowsheet performance has been identified for investigation in the near future.INTRODUCTIONLocation and Description of the Kamoa DepositThe Kamoa copper resource is located some 40 km west of the city of Kolwezi, in the south west of the Katanga Province of the Democratic Republic of the Congo, in the region of Central Africa. Drilling at Kamoa in 2008-2009 had discovered laterally continuous, sediment-hosted, high-grade stratiform copper mineralisation in a newly discovered copper district that forms a previously unrecognised western extension of the famous Central African Copperbelt – which hosts such world-class deposits as Kolwezi, Tenke-Fungurume, Konkola and Nchanga. This discovery showed that the western end of the Copperbelt in the Congo does not terminate at Kolwezi (Friedland & Broughton, 2009). The resource contains hypogene and supergene geomet units with a transitional zone located inbetween the (upper) supergene and the (lower) hypogene. In the hypogene unit, the major copper sulphides are bornite, chalcopyrite and chalcocite, whilst in the supergene, the sequence is led by chalcocite, then bornite, and finally chalcopyrite. Covellite is present in both units as a minor copper sulphide. Both geomet units will be mined and treated in one concentrator, either as blends or as campaigns."

Jan 1, 2013

By Evgenii Pavlov, Ivan Tronin, Viktor Timofeev, Vladimir Kislov, Sergei Bogovalov

"Modeling of the magnetohydrodynamical (MHD) and thermodynamical processes during the industrial scale Direct Chill (DC) casting of aluminum slabs is performed using a combination of ANSYS/CFX and ANSYS/EMAG software. The electromagnetic field is modeled through ANSYS/EMAG, while hydrodynamic and thermodynamic processes are modeled through ANSYS/CFX. Both packages were modified in order to calculate MHD flows in the liquid pool that forms during aluminum DC casting, and they were unified into a software combination that provides simultaneous simulation of all the above processes. The simulation shows that the electromagnetic stirring of the molten aluminum changes the shape of the solidification front (solid-liquid interface) very dramatically, namely it becomes significantly flatter. This effect should improve the internal structure of aluminum DC slabs and allows us to increase the casting velocity.IntroductionProduction of Aluminum alloys with high mechanical properties and structural uniformity is one of the main goals of industry. The preferred production method of aluminum alloys in most modern plants is Direct Chill (hereafter DC) casting because it offers high productivity and commercial success. One important limitation of this technology is the development of centerline shrinkage in slabs larger than about 1 meter. The improvement of the internal structure of long DC cast slabs can be achieved by electromagnetic stirring (hereafter ES) of the liquid metal above the solidification front. This intensifies heat transport in the zone close to the solidification front and suppresses shrinkage formation."

Jan 1, 2013

By Joseph R. Hatch

Previous studies of the Thompson and Temperly ore bodies show alteration aureoles in the Middle Ordovician host-rock limestones, dolomites and shales extending laterally as much as 60m from the ore. Thickness, texture, carbonate and clay mineralogy, major-, minor-, and trace-element contents; and carbonate carbon and carbonate oxygen Isotope compositions of the host rocks all have been significantly altered by hydrothermal processes. Organic geochemical analyses of samples from the basal 8-cm-thick carbonaceous shale bed and immediately overlying limestone bed of the Quimbys Mill Member of the Platteville Formation, collected from within the ore, the alteration aureole, and the unaltered country rock show: 1) solution of carbonates and residual concentration of organic matter, 2) decreases in the volatile (Si) and pyrolytic (S2) hydrocarbon yields In samples of the basal shale from within the ore, 3) decreases in the relative amounts of the lower molecular weight (<nC25) saturated hydrocarbons in samples from the ore, and 4) no changes in either the organic carbon isotope composition or the Rock-Eval or biomarker thermal maturation Indicators. In light of the 125-170°C depositional temperatures documented for the early marmatitic sphalerltes in these deposits by fluid Inclusion studies, the lack of thermal alteration of the organic matter suggests a relatively short mineralization episode, a conclusion supported by the relatively simple sphalerite band stratigraphy. The decreases in the volatile and pyrolytic hydrocarbon yields for shale samples from the ore supports a model for mineral deposition which obtains sulfide through reaction of brine sulfate and indigenous organic matter.

Jan 1, 2013

By R. W. Macqueen

Organic matter commonly associated with Mississippi Valley-type (MVT) lead-zinc deposits may be used to assess the burial/thermal history of host rocks and sulfides. Organic matter may also have been involved in the genesis of H2S required to precipitate sulfide ores. Pine Point, Northwest Territories, Canada, provides an example. Located on the south shore of Great Slave Lake, Pine Point is an operating world class deposit which has produced 58 million tons of ore containing 3.0 percent Pb and 6.1 percent Zn from more than 40 Individual orebodies. Well-documented paleokarst features in a Middle Devonian carbonate complex are the main ore hosts. Sphalerite and galena ores are mainly open space fillings, and, from fluid inclusion studies, were deposited from saline fluids at temperatures of up to at least 100°C. Forms of organic matter occurring in the Pine Point barrier-reef complex Include indigenous organic matter, heavy oil and bitumen. Based on numerous geochemical criteria, it is clear that heavy oils and bitumens were derived locally from indigenous organic matter. The geochemical character of the Indigenous organic matter demonstrates that the barrier-reef complex is immature to marginally mature with respect to petroleum generation, and has not been heated above about 60°C maximum. Thus sphalerite with fluid inclusions that yield temperatures up to about 100°C represents former thermal anomalies. Bitumen is of two main forms at Pine Point: widespread soft, tarry material soluble in organic solvents (unaltered bitumen); and hard, brittle, glassy material that is mostly solvent-insoluble, and associated with white sparry dolomite and lead-zinc ores (altered bitumen). There are also partly altered bitumens. Unaltered bitumens have atomic H/C ratios of about 1.4, sulfur contents averaging 7.8 percent, and sulfur isotope ratios 634S) of approximately +4.6 per mil. Altered bitumens have atomic H/C ratios averaging 1.02, sulfur contents averaging 22 percent, and 634S values of about +12.9 per mil. These data and the organic geochemical character of a large suite of bitumen samples analyzed, strongly support the concept that some bitumen has been involved in the thermochemical reduction of sulfate to produce the H2S required to precipitate the ores. Mass-balance calculations indicate that the amount and degree of alteration of bitumen is more than enough to account for the reduced sulfur species deposited as metallic sulfides at Pine Point. MVT deposits, including Pine Point, seem to require the coincidence of available metallic Ions, pre-existing pore space, and a precipitating agent. A close look at organic matter in more MVT settings may outline trends in distribution or alteration which can be used as indicators of past thermal environments and processes of ore deposition.

Jan 1, 2013

By Andrew P. Gize

A petrographic approach to studying the organic matter in ore deposits is advantageous in that direct observation of sample heterogeneity can be made, organic constituents (macerals) can be identified, and valuable information about the geological history of the sample (such as thermal history, oxidation, and reworking) can be obtained. Thermally immature bitumens are compositionally and structurally heterogeneous, and optically isotropic. The end product of thermal alteration, graphite, is compositionally and structurally homogeneous, and optically an isotropic. One route by which thermally immature bitumens can approach the graphite structure Is by an aromatic intermediate phase, termed mesophase. The development of optical anisotropy and a thermal mesophase has been observed In several high temperature deposits. Textures in bitumens are described from the thermally-altered Mississippi Valley-Type deposit at Nanisivik (Northwest Territories), the silver-vein deposit at Kongsberg (Norway), and the gold deposit at Carlin (Nevada). Textural evidence for multiple generations of bitumens, supportive of a pulsing model for incoming brines, is shown. Petrological evidence for the introduction of bitumens as an immiscible phase or possibly as micelles is shown in the Carlin and Kongsberg deposits.

Jan 1, 2013

By Yuan-bo Zhang, Gui-hong Han, Yan-fang Huang, Tao Jiang, Guang-hui Li

"Under isothermal conditions, the reduction behavior of oxidized pellets balled with bentonite was investigated with CO-CO2gas mixers in the temperature range from 900°C to 1100°C. The whole reduction of oxidized pellets was followed up by means of weight-loss technique. And the swelling index of pellets was examined by visualizing physical changes of pellet in a horizontal tube furnace. The results present that the reduction rate of oxidized pellets is increased with the increase of reduction temperature. While the swelling index is firstly increased and then decreased with the increase of reduction time and reduction extent, which can be ascribed to the disruptive stresses induced during the transformation of hematite to magnetite. The maximum swelling index is gradually increased with the increase of reduction temperature and CO content.IntroductionWith the rapidly development of iron and steel industry, direct reduction iron has been considered as one kind of high quality burdens in electric furnace steelmaking [1]. At present, ""Two-step"" coal-based direct reduction process, which employs oxidized pellets as raw materials, has been used in industrial production [2]. The reduction behavior of iron ore oxidized pellets has been becoming one of the most frequently studied topics in extractive metallurgy[3]. The heat and mass transfer in direct reduction processes results in a series of stepwise reduction reaction (hematite--magnetite--wustite--iron), accompany with the volumetric swelling of pellets[4]. A lot of literatures have been reported on the reduction model of ferrous oxides and swelling behavior of pellets. A. A. El-Geassy K, et.al [5-7] revealed that the reduction process was controlled by chemical reaction at early stage by employing pure Fe203 as raw materials and CO as reduction gas. Chen Y [8] made research on the reduction kinetics of porous oxidized pellets and obtained the rate constant and activation energy of at different reduction stage. In addition, the swelling and disintegration of iron ore pellets was affected by chemical composition of pellet and reducing parameters, which have been studied by numerous investigators [3,9, 1O]."

Jan 1, 2013

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the high noise is the drilling of the roof bolt holes, especially in hard rock. A previous research shows that the specific energy consumed in drilling the bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process to produce heat, bit wear and noise. Therefore, control of drilling operation to achieve a higher bite depth can provide an opportunity to reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and to develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show significant reduction in noise dose can be achieved by drilling in medium hard rock at a reasonably high bite depth. This paper presents the findings from the laboratory experimental studies conducted so far.

Jan 1, 2013

By C. Edwards

ABSTRACT The versatility and specificity of rare earth elements (REEs) have led to their use in an everincreasing variety of applications in new technologies; consequently, demand for REEs has increased significantly. However, separating REEs safely and effectively is a complex and expensive process. This paper presents a review of REE mineral processing technologies, providing an update on current capabilities in REE mineral processing and REE extraction from the major commercially valuable REEbearing minerals such as bastnaesite, monazite, and xenotime, as well as the ion-absorption type of REE deposits.

Jan 1, 2013

By Zhucheng Huang, Zhikai Liang, Lingyun Yi, Tao Jiang

"In this study, reduction of iron ore pellets was carried out at 800-950°C by simulating the atmosphere of typical coal gasification gas. The effects of temperature, gas composition and reduction degree on swelling were investigated respectively. Reduction degree was obtained according to the weight loss records. And volume changes of pellets during reduction were evaluated by infrared photography. Results showed that the pellet swelling increased with temperature and decreased slightly with hydrogen content in the reducing gas. The swelling peaked when reduction degree reached about 40% and then decreased to be stable finally. The microstructures of pellets during reduction were examined by reflected light microscope and relatively rational explanations were proposed for their swelling behaviors.PrefaceDirect reduction iron is an important and indispensable raw material for high-purified and high-quality steel in the electric furnace smelting. Gas-based shaft furnace direct reduction process has very strong competitative ability; however, this technique requires natural gas as reducing agent, so its development has been restricted by gas source and area. Compared with gas-based reduction method, coal based reduction method has the disadvantages of higher production cost and lower productivity. In China, coal resources are abundant and coal gasification technology is mature, and the development of coal gasification shaft furnace direct reduction process is promising. [1] The gasification methods of fixed bed method (Lurgi method), fluidized bed method (Undok method), airflow bed method (Texaco coal water slurry method and Shell dry powder coal method) have been put into use successfully. These syngas generated by different methods can meet the actual production requirement of shaft furnace. However, the compositions of the effective reduction gas in the syngas are quite different. The ratios of hydrogen and carbon monoxide (H2/CO) of Undok or Shell coal gas, Texaco coal gas and Lurgi coal gas are 0.4, 0.6~ 1.0 and 1.6~2.3, respectively. [2] In the coal gas direct reduction process, the swelling behavior of iron ore pellets is various due to the differences of the gas composition, reduction temperature and reduction degree, and it seriously affects the normal operation ofDRI production. [3-9] Therefore, the research on the swelling behavior and its mechanism of iron ore pellets in direct reduction were carried out in this paper."

Jan 1, 2013

By Osama A. Safaqah

Driven plate anchors can be used to hold in place large bridge caissons during floating construction. Their small size and simple method of installation make them a very cost effective alternative to other direct-embedment, gravity, and drag anchors. The geotechnical design of plate anchors involves the anchor geometry, embedment, drivability, and proof testing. This paper describes the experience gained with plate anchors used during construction of the new Tacoma Narrows Bridge. For this project, the anchors had to be driven in dense to very dense sands, and had to resist large forces from 7-9 knot currents.

Jan 1, 2013