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By Zhao wen Wang, Ramana G. Reddy, Min Li

"The electroreduction of Co(II) in l-butyl-3-methylimidazolium tetrafluoroborate (BMlMBF4) ionic liquid was investigated by cyclic volatrnmetry at 353 K. The results show that the reaction of Co(II) to Co is irreversible in one step with two electrons transferred. The diffusion coefficient of Co(II) was estimated to be 7.6 x 10-8 cm2 s·1 at 353 K. Then the electrodeposition of cobalt was studied at different cathodic potentials (-0.80 to -0.95 V) and different temperatures (333 to 363 K) in BMIMBF 4 containing 0.20 mol L-1 Co(BF4)z. The deposits were characterized using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). SEM images show that a uniform, dense, and compact deposit was obtained at -0.80 V and 333 K. The deposits were identified as high-purity metallic Co for all experiments by EDS and XRD.IntroductionCobalt is known as a hard magnetic material and cobalt alloys have been shown to have excellent magnetic properties with adequate mechanical durability and corrosion resistance, which are needed for high performance magnetic recording applications [1-4]. The electrodeposition of Co alloy in the aqueous solution is generally difficult because of the narrow electrochemical potential window of water, which leads to the low current efficiency and worse quality of deposits due to the hydrogen embrittlement. Thus, aprotic ionic liquids (ILs) are expected to be the ideal alternative media for electrodeposition of cobalt or its alloy since ILs usually provide a wide working potential windows, negligible vapor pressure, and acceptable conductivity for electrolysis without the occurring of hydrogen evolution [5, 6]."

Jan 1, 2014

By L. A. Neumeier

The Bureau of Mines, U.S. Department of the Interior, is investigating the feasibility of partitioning complex sulfide minerals to simpler sulfide .phases by sulfldation reactions. Such partitioning can afford opportunity to improve selective extraction of mineral constituents of value. This report describes initial research involving sulfidation partitioning of chalcopyrite concentrates. Small chalcopyrite samples were sulfidized with elemental sulfur in glass capsules sealed after evacuating and backfilling with helium, by heating for 1 to 24 h at specific temperatures in the range of 250° to 500° C. which extends from below to above the boiling point of sulfur (-445° C). Above the boiling point of sulfur, the overall reaction with adequate sulfur (13.9 wt pct of CuFeS2) is 5CuFeS2 + 4S g ? Cu5FeS6 + 4FeS2.

Jan 1, 1989

By Ralph H. Nafziger

The feasibility of smelting a Ni-Co-Cr-bearing laterite ore from southern Oregon was evaluated by the Bureau of Mines. The objective was to prepare a master alloy for subsequent stainless steel production. A mixture of the ore with suitable reductants and fluxes was smelted in a 50-lb-capacity single-phase ac electric furnace under sub- merged arc conditions. The smelting tests produced a metal in which most of the nickel was concentrated. High-chromium recoveries required an excess of carbon. The resulting metal alloys contain sufficient nickel for some stainless steels. Ferrochromium additions would be required to attain suitable chromium levels. This research was conducted under the Oregon Metals Initiative in cooperation with Walter B. Freeman.

Jan 1, 1993

By Shunhong Huang

Thirty-five soils were sampled from three sites at different distances from chromium slag heap of a Iron-alloy factory, namely, nine from site A located under the chromium slag and eighteen from Site B in the vicinity of the factory and eight from site C far from the factory. The contents of total Cr in these soils from site A, B and C were 1666.0±1310.9 mg? kg - 1,1136.2±1844.6 mg? kg - 1 ,300.4 ±165.1 mg? kg ? 1, respectively. The contents of water soluble Cr were 59.3±77.57 mg? kg ? 1,0.6 ±0.3 mg? kg - 1 ,0.5±0.3 mg? kg - 1 , respectively. In order to evaluate soil health, the activities of four soil enzymes (catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatases) were analyzed. The results have shown that dehydrogenase activity was greatly depressed by conditions in the heavy chromium-contaminated sites. Negative correlation was observed between dehydrogenase activity and the distance from the chromium slag heap, however, the activities of catalase, polyphenol oxidase, alkaline phosphatases in soils from the three sampling sites mentioned above did not differ significantly. The result imply that of dehydrogenase activity could be used as an indicator for the chromium pollution level in the area of Iron-Alloy factory and for the stability level of the soil ecosystem.

Jan 1, 2008

By Tadashi Aiura, Yasuhiro Miura

"A small amount(0.2mass%) of Scandium(Sc) was added to the 7.NOl and 5083 Al alloys as a refiner and stabilizer of microstructure, and the resulting microstructures were discussed in comparison with the effects of the conventional additives. The followings are summarized: 1) in the as-solidified structure, a ·decreased tendency of constitutional supercooling and increased solubility of Mg were recognized for the Sc-added 5083 alloy. Sc is a -better microstructure refiner for the 7N01 alloy than Zr, in a sense that it does not suppress the favorable effect of· coexisting Ti. 2) Sc effectively suppresses recrystallization both in the 5083 and 7N01 alloys. 3) The rod like primary Al3Sc crystals formed during solidification, as well as the fine dispersion of Al3Sc precipitates formed by subsequent heat treatment, can act as a strong recrystallization suppresser. IntroductionThe 7N01 and 5083 alloys are the most popular industrial Al alloys and they are widely' used for various structures because of their superior properties. Fine macro and micro structures of the materials are required for obtaining acceptable sec resistance,consistent appearance of anodized surface and good weldability, as well as good mechanical properties. In order to produce fine grain structures, transition metals, such as Cr, Zr, and Mn, have been conventionally added.It has been reported that Sc is an efficient refiner [l, 2] and can be an alternative for the conventional and also suppresses recrystallization in Al alloys [3,4]. Scandium is the lightest transition element and forms an equilibrium intermetallic phase. The equilibrium phase, Ll2-Al3Sc, is coherent with the matrix, and of _spherical shape. A fine dispersion of the spherical precipitates is obtained by quenching and aging after solutionizing annealing. The authors have already reported a part of the experimental results on the effect of Sc on the as homogenized microstructure of the 5083 alloy [5]. In the present study, the effects of Sc on the macro and micro structures of the industrial high strength Al alloys(7N01 and 5083) for extrusion are investigated, and the superior role of Sc as a grain refiner is shown"

Jan 1, 2000

By M. L. Cunha

The lack of control of As and Sb compounds from copper smelters and converters has rendered some chalcopyrite containing arsenopyrite, stibnite and tetrahedrite minerals unusable for metal extraction. In the present investigation, we have studied the carbothennic reduction of Portuguese chalcopyrite mineral concentrate in the presence of lime/CaS04 and CaS04/Si02. Thermodynamic equilibrium calculations were performed to study the distribution of As and Sb between metal and the CaO-Si02-FeO slag phase. The phase equilibrium calculations also show the effect of oxygen partial pressure on the increase in the volume of the slag phase, which helps in lowering the copper metal formation temperature and facilitates a better separation between metal, matte and slag. The reduction reaction kinetics was studied between 850°C and 1100 °C, and the phases formed were identified by X-ray powder diffraction and scanning electron microscopy techniques. The importance of this research for using recycled matte, lean and rich minerals with As and Sb is also explained.

Jan 1, 2001

By G. C. Gullo, H. Wabusseg, P. J. Uggowitzer, H. Kaufmann

"The basic concept of New Rheocasting (NRC) is described and the application of wrought alloys with this process is discussed. Practical experiments with the aluminium alloy AIMgSi I are explained. For this alloy the proper NRC - casting temperature was determined by using Thermo Cale - computer software and DT A and the essential processing conditions are shown. In the experiments the melt was taken from an aluminium holding furnace and cast into NRC steel cups. After controlled cooling the resulting slurries were cast into a 4-step die on an UBE HVSC 350 Squeeze Casting machine. The characteristic microstructural values such as grain size and shape factor were measured and compared with classical casting alloys. The influence of the wall thickness of the step part (6 mm, 10 mm and 14 mm) on the microstructure is described. Tensile properties in different heat treatment states are compared with characteristic prope1ties of the same alloys in forged condition. The ew Rheocasting - process CNRC)The NRC process is a recently developed new semi-solid processing method which allows the production of pore-free, pressure tight components.In the NRC process a fu lly liquid, but only slightly superheated melt is taken from a holding furnace and poured into specially designed steel crucibles, which are placed on a carousel next to the Vertical Squeeze Casting machine. In this ,NULL,slurry maker'· globul ar a-Al grains grow, following forced homogeneous nucleation at the cup wall [ 1, 2]. In the few minutes during which the melt is cooled to sem i-so lid processing temperature, a stable ske leton of a-Al phase forms. The resulting slug keeps a cylindrical shape during its slide into the sleeve of the Vertical Squeeze Casting machine, where it is cast into shape."

Jan 1, 2000

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By J. Fraser Forbes

"The meaning of the term ""process control"" has evolved significantly since its widespread use began in the manufacturing industries in the 1940s. Further, the scope of process control applications has drastically increased both in terms of the breadth of industries using process automation technologies and the vertical integration of these technologies within a single industry. This evolution and integration of process control technologies within the manufacturing industries has proceeded to such an extent that process automation is an integral part of modern business practices.This paper will examine the current status of process control technology from simple process regulation through process performance optimization to business planning. Each layer of the operations automation hierarchy will be discussed both in. terms of the current state-of-the-art and the directions in which these technologies are evolving. The key tools and tasks necessary for success at every level of the automation hierarchy will be introduced. Finally, the critical challenges that must be faced in accomplishing the goal of complete Computer Integrated Manufacturing (CIM) will be described.Finally, although this paper addresses issues of practical importance to any manufacturing company, the discussions will be framed in terms of the particular challenges facing and the opportunities available within the materials manufacturing industries."

Jan 1, 2000

By Hongbo Zhu, Jinhui Peng, Linqing Dai

"To optimize the process variables for making direct reduced iron (DRI) by microwave heating, the reduction temperature, reduction time and the ratio of coal to material were studied with the central composite design (CCD) and their interactions on the Metallization rate were also investigated. The predictive polynomial quadratic equations model was analyzed by ANOVA. Optimal conditions of making DRI can be concluded as follows: 28 min at 1139?, the ratio of coal to material is 20.95%. Under these conditions, the metallization rate is up to 97.06%.1. IntroductionThere are some technical problems in making direct reduced iron (DRI) or sponge iron using iron ore concentrates containing coal and lime. In reduction of the iron ore concentrates containing coal with microwave heating, the strength of pellets needn’t to be considered. It reduces the costs and improve quality of materials, but also eliminates the need for pellet preparation process, simplifying the process and achieving a cleaner production.Microwave energy is a clean energy, and has characteristic of selective heating. The speed of heating is also fast. It researched by Chen Jin that when the mole mass of C: O is 0.627 and the microwave power is 15KW, it only spends 15min from 15? to 1021.6? with 1 kg iron ore containing coal with microwave heating [1]. There are many factors affecting metallization rate. In order to find a suitable condition for reduction process, it is necessary to design a series of suitable experiments.Response surface methodology (RSM) is one of the relevant multivariate techniques which can deal with multivariant experimental design strategy, statistical modeling and process optimization [2–5]. It is used to examine the relationship between one or more response variables and a set of quantitative experimental variables or factors. This method is often employed after the identification of the vital controllable factors to find the factor settings that optimize the response. Designs of this type are usually chosen when a curvature in the response surface is suspected. The process optimization of the microwave reduced iron ore was seldom reported in literature. Hence the present work intends to assess the effects of variables such as reduction time, reduction temperature and the ratio of coal to identify the optimum conditions using a central composite design (CCD). The characteristic of product was assessed using scanning electron microscope (SEM)."

Jan 1, 2011

By Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping, Zhai Dacheng

"Corrosion resistance of RE-Ni-W-P-SiC composite coating and 3 l6L stainless steel in corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations by means of immersion methods and anodic polarization curves obtained by DHZ-1 electrochemical synthetic tester and HDV-7 transistor constant potentiometer. Immersion experiment results show that corrosion rate of RE-Ni-W-P-SiC composite coating as-deposited in HCl solutions increases with the rise of HCl concentrations, on the contrary, the corrosion rate of the composite coating after heat treatment decreases with increasing the HCl concentrations the corrosion rates of the coatings as-deposited and after heat treatment in H2SO4 and H3PO4 solutions respectively decrease with the rise.of H2SO4 and H3PO4 concentrations the corrosion rate of the deposit as-deposited in FeC13 solutions decreases with increasing FeC13 concentrations, while the rate of the composite coating after heat treatment increases .with the rise of FeC13 concentrations.In addition, the corrosion rate of 3 l 6L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations increases with rising of concentrations. Furthermore, the corrosion rate of 316L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions respectively is much greater than that of the RE-Ni-W-P-SiC composite coating as-deposited and after heat treatment in the same corrosion media.1. IntroductionAll the materials and their products, when processed, stored and used, it is inevitable that the corrosion, wear, fatigue and crack occur owing to the actions of surroundings. Those early failure and abrasion, through all kinds of departments and profession that corrosion consumes one percent of tens of the steel products of the whole world; and two or four percent of the GDP is lost because of the corrosion."

Jan 1, 2000

By Y. Maeda

Kosaka Smelter is a copper smelter located at the nothern part of Japan? and has been treating. complex sulfide concentrates using flash smelting technology for a long time. The flash smelting technology has an advantage in the point of controllability of matte grade and heat balance in the reaction shaft. But the disadvantage of this process, is that the dust generation ratio is high compared with other smelting process such as injection smelting technology. This reason why is that the flash smelting process is the oxidation process for the fine sulfide concentrates applying flash reaction in the oxygen enriched stream In addition of this disadvantage, the sulfide concentrates contains much volatile impurities is resulted the dust; eneration ratio more. This paper outlines the recent improvement of the flash reaction in the furnace and the behavior of impurities in Kosaka Smelter.

Jan 1, 1998

By G. Kyle Green

Zirconium chlorinator residues contain an array of rare earths, scandium, unreacted coke, and radioactive thorium and radium. Because of the radioactivity, the residues must be disposed in special waste containment facilities. As these sites become more congested, and with stricter environmental regulations, disposal of large volumes of wastes may become more difficult. To reduce the mass of disposed material, the U.S. Bureau of Mines (USBM) developed technology to recover rare earths, thorium and radium, and unreacted coke from these residues. This technology employs an HCl leach to solubilize over 99% of the scandium and thorium, and over 90% of the rare earths. The leach liquor is processed through several solvent extraction stages to selectively recover scandium, thorium, and rare earths. The leach residue is further leached with an organic acid to solubilize radium, thus allowing unreacted coke to be recycled to the chlorinator. The thorium and radium waste products, which comprise only 2.1% of the original residue mass, can then be sent to the radioactive waste facility.

Jan 1, 1995

By J. -S. Park, H. -S. Jeon

This study has been carried out to develop a relatively simple hydrometallurgical process for recovering nickel as nickel sulfate from the spent nickel-cadmium battery residue in which cadmium was removed by vacuum distillation. This residue is composed of 36 % nickel, 20 % iron, and other metals such as cobalt. First, crushing and selective classification were performed to separate iron to produce a nickel-rich product (over 40 % nickel). This product was dissolved in sulfuric acid to obtain a nickel sulfate solution. During the dissolution, nitric acid and air were added to the system to enhance the iron oxidation reaction rate. The free acid remaining in the dissolved solution was neutralized by adding nickel carbonate. Iron was precipitated as iron hydroxide and removed from the solution. The nickel sulfate solution was then fed to a vacuum evaporator to concentrate the solution by evaporation of water and crystallized at around 45°C to obtain nickel sulfate hexahydrate. A recrystallization process could remove other impurities such as zinc and manganese.

Jan 1, 2000

By ZHANG Ting

In view of the high consumption and contamination of traditional vanadium extraction technology, a new process of leaching the converter vanadium slag without roasting with titanium dioxide waste was proposed. Extraction mechanism of P204 in the leaching solution had been researched and single factor experiments show that after a prereduction of Fe, and under conditions: ambient temperature，leaching solution original pH=2.5, phase ratio (A/O)=1:3, shaking time 8min, the extraction rate of V is more than 98.62% meanwhile the separation rate between V and Fe is up to 135.3 in the 20%P204-10%TBP-Sulfonated kerosene extraction system.

Jan 1, 2015

By Lin Li, Xiang Li, Yifang Zheng, Jilai Xue, Jun Zhu

"Al drops and gas bubbles in the anode-cathode space of aluminum electrolysis cell are of great importance for cell operation improvement in metal loss, current efficiency and energy consumption. A direct observation on the Al drop, gas bubble and ultrasound was carried out through a see-through cell. The Al drop immersed into the cryolitic melt was found moving up and down irregularly in the anode-cathode space without electrolysis, which was then completely dissolved into the melt. During electrolysis, the Al drop came to the anode area and reacted with the gas bubbles generated on the anode. Under ultrasound, the gas bubbles were removed from the anode surface while the Al drop was kept on the side of anode. The observed phenomena were useful for technology improvement in reducing the anode-cathode distance or lowering the energy consumption in aluminum electrolysis.IntroductionDuring aluminum electrolysis, aluminum metal drop and anodic gas bubble are in close contact each other within the anode-cathode space, and the interaction between them can produce significant impact on metal loss, current efficiency and energy consumption. The motions of the Al drop and the gas bubble are also related to the dissolution of aluminum metal into cryolitic melt and the cell voltage drop due to the bubble layer covering the anode surface.A number of studies have been carried out using different types of see-through cells, where the dissolving process of metal Al into cryolitic melts (metal fog) in the anode-cathode space was directly observed and photographed [1, 2]. With the similar method, some direct observations on the anodic bubble behaviors with and without ultrasound were performed during aluminum electrolysis [3-6]. However, to our best knowledge, there is no published work on direct observation on the behavior of Al drops and anodic gas bubbles staying together within the same anode-cathode space, as well as the motion and interaction of them in cryolite-alumina melts."

Jan 1, 2011

By Raj P. Singh

Applications of cementation in the recovery of metal ions from process solutions have been known for a long time. Cementation reactions involve electrochemical precipitation of a noble metal from solutions of its salts on a more electropositive metal which, in tum, progressively dissolves. For example, addition of zinc metal powder in a solution containing zinc and cobalt ions would allow for the precipitation (separation) of cobalt according to the following chemical reaction. This paper pertains to the recovery of cobalt from cobalt process solutions via a cementation reaction on aluminum shavings (metal scraps from cans etc). Specifically, we report on the characterization of cobalt process solutions, a by-product obtained from cobalt chemicals, and the kinetics of cobalt, nickel and manganese cementation from process solutions on aluminum shavings.

Jan 1, 2000

By Jiayan Li, Yi Tan, Yao Liu, Yaqiong Li, Shenrui Wu

"A metallurgical grade silicon (MG-Si) refining concept process was presented. Under vacuum conditions, silicon was selectively oxidized by high purity silicon dioxide to form gaseous silicon monoxide while impurities with low vapor pressure in MG-Si were rejected in residue; Then high purity silicon was obtained from the disproportionation of condensed silicon monoxide; and by-produced silicon dioxide was recycled for the oxidation step. Thermodynamics on boron rejection during the oxidation were studied in this work. In the temperature range of 1200-1800K, the saturated vapor pressure of boron, and the Gibbs free energy changes, the equilibrium partial pressures of silicon monoxide and boron oxides of potential reactions were calculated. And the effect of boron activity in MG-Si was also discussed. The results indicated that boron in MG-Si can be rejected during the oxidation and it showed the potential for the further development of the new refining process.IntroductionAs global energy consumption growing dramatically, higher prices of energy and global warming problem have attracted more and more attention [1]. As a clean and renewable energy industry, the photovoltaic (PV) industry converts solar energy to electricity using solar cell device and has a growth rate of about 30% in recent years. It has caused a shortage of silicon feedstock due to that about 90% of solar cells are made of crystalline silicon. And high energy consumption during the production of silicon material, i.e. solar grade silicon (SoG-Si), is main obstacle for its mass production."

Jan 1, 2012

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By Jose Bengoa

Low metal prices and environmental restrictions are always a challenge for copper smelters operation and its productivity. Thus, in order to reduce production costs and control gas emissions, improvements of the Teniente Converter (CT) operation were made at 110 Smelter Plant of Southern Peru Copper Co" 110, Peru, and the main objective was to increase its capacity for smelting copper concentrates without affecting normal operation, The present work eorresponds to a recent study conducted during the normal industrial operation of the Teniente Converter in this plant and, it shows the effect of increasing air oxygen enrichment from 28 to 34% on its productivity. The results show an increasing of concentrate smelting rate from 800 to 1370 tpd and hence a notorious improving in copper production, and practically no effect on the refractory consumption. The increment of the concentrate throughput, increases also the SO2 concentration and the sulfuric acid production, showing the effort done by this operation in order to accomplish the environmental Peruvian regulation,

Jan 1, 2003