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By Frederick T. Wallenberger

"Laser assisted chemical vapor deposition (LCVD) is a new containerless fiber process whereby growth of small diameter fibers or microstructures (microsprings, microsolenoids) occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber inside the reaction chamber. Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Continuous fibers and multifilament yams are possible. The use -of high reaction chamber pressures (1-10 bar) and a small wavelength Nd-YAG laser made it possible to fabricate small diameter fibers at growth rates >1 mm/s. This paper describes the synthesis of single crystal, polycrystalline and amorphous fibers by LCVD, and provides a comprehensive analysis of phase transformations occurring during their fabrication.IntroductionLaser assisted chemical vapor deposition (LCVD) is a new containerless fiber process [1-10] whereby growth of small diameter fibers or microstructures occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber in the reaction chamber (Figure 1). The diameter of the growing fiber corresponds to that of the laser focus. Depending primarily on the laser energy (Le., the temperature at the growing fiber tip), it is possible to obtain single crystal, poly crystalline or amorphous fibers by this method.Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Laser assisted CVD is a potentially continuous process; continuous fibers and multifilament yams are possible."

Jan 1, 1994

By Zhihua Wang

Through metallurgical calculation and process analysis based on metallurgical theory, it is aimed to raise the concentration of smelting oxygen and improve the update speed of reaction interface, accelerate the reaction and achieve a high-intensity smelting at the stage of converting. The PM plant has launched a theoretical research on model of high-intensity converting aiming at increasing the oxygen concentration of converting, carried out transformation of Kaldo furnace converting system, performed a series of industrial trial operations, conducted multiple rounds of tracking test and data comparison in reducing the furnace cycle, lowering the unit consumption of fuel and stabilizing the furnace lining life. The move has practically tested and verified the correctness of high-intensity smelting theory.

By Finlay Campbell

Nickel laterite pressure acid leach plants and reduction roast plants have had a checkered history in their engineering, construction, startup and operational reliability. Many potential projects have been the subject of detailed studies over the last thirty to forty years but relatively few have advanced to commercial production. Four reduction roast plants are currently operating, an additional one was partially constructed but never completed, and another was started up in 1974 and shut down after 12 years operation. Three acid leach plants have been built and commissioned in the last five years, trying to follow the example of the Moa Nickel plant in Cuba. An additional acid leach plant project is currently on hold, following limited construction work, its future subject to review by the owner because of potential cost over-runs. This paper attempts to discuss difficulties that may be encountered as a project is developed and will address factors which may affect production ramp-up schedule, long term production performance and overall production success. Comparisons are made with ramp-up performance at other large metallurgical plants that employ some comparable unit operations. Keywords: Caron, PAL, nickel laterite ore, ramp-up, reliability, process development, equipment design, step-out, commissioning, startup.

Jan 1, 2004

By H. -Peter Sattler

The laser sorting technique for replacing the handpicking of the non-ferrous metal scrap from auto shredders was first introduced 1990, The process is based on the use of atomic emission spectroscopy induced by lasers to identify the scrap particles and sort them with adequate systems into main fractions of Al-, Zn-and Cu-alloys, stainless steel and lead, In the meantime the handling technique for the scrap, i.e. the singling and sorting technique as well as the analytical detector were further developed for more efficiency and higher reliability, i,e. less maintenance, minor sorting errors etc. These developments were mainly based, on and initiated by operational experiences from the startup phase of a first production plant. Part of the on going research work was the development of an ,aluminium detector which makes it the first time possible to sort mixed aluminium scrap automatically into specific alloy fractions.

Jan 1, 1995

By Jing Lin, Yuan Xu, Qingcai Liu, Dengfu Cheng

"Smelting reduction technology has been developed greatly in recent years. But one of the key problems for this technology is about the refractory that used as lining material in the molten bath. Investigation and test shown that corrosion rate of refractory was much higher and the corrosion mechanism was much more complexity in the molten bath of smelting reduction with iron bath than that of the blast furnace and rotary furnace technology [l-5]. The corrosion behavior and corrosion rate of Al2OrC-ZrO2 series refractory in the melt of smelting reduction with iron bath have been studied by rotary immersion and quasi-static immersion test in this paper. The major factors that affect the interaction between the melt and refractory were investigated. The test results shown that the corrosion rate of AI2O 3-C-ZrO2 series refractory decreased with the ZrO2 increasing when ZrO2 content was from 3% to 10%. Ferrous oxides content, relative moving speed between the melt and refractory and temperature of the molten bath were the important factors that affect the corrosion rate. But the ferrous oxides concentration was the most important one. The corrosion rate was increased as a linear relation with the rising of ferrous oxides content of the melt. The corrosion rate in the quasi-static immersion was much less than that of the dynamic immersion (rotary immersion) for the Al2O 3-CZrO2 series refractory in the same testing condition. The corrosion mechanism of Al2OrC-ZrO2 series refractory is: graphite oxidized in advance, then interaction between the constituents of refractory and melt taken place and deteriorate layer of refractory and new compounds were formed, the properties of refractory was changed.IntroductionSmelting reduction with iron bath is a typical technology [3, 4, 6]. The obvious features of the melt for smelting reduction technology with iron bath are much higher ferrous oxides and much more complexity melt composition and structure than that of the blast furnace technology [2, 5-8]. The properties of the melt were changed dynamicilly and constantly in reduction process. On the other hand, the behavior of the melt depends on the activity and the reduction rate of ferrous oxides in the molten bath[9]. Because of the high concentration of ferrous oxides in slag and high reduction rate in the molten bath, the corrosion behavior and corrosion mechanism of the refractory lining by melt are an important factor in development of the technology of smelting reduction with iron bath. Up to now, improving refractory quality to anti-corrosion of melt and developing high quality and long term refractory used as the lining refractory materials in the molten bath of the final reduction furnace are also the most important questions for developing smelting reduction technology."

Jan 1, 2000

By Tina Maniatis

Applied Biosciences has developed a biological technology for removal of arsenic, nitrate, selenium, and other metals from mining and industrial waste waters.The ABMet® technology was implemented at a closed gold mine site in Canada for removing arsenic from tailings pond water. The system included six bioreactors that began treating water in the spring of 2004. Design criteria incorporated a maximum flow of 567 L/min (150 gallons per minute) and water temperatures ranging from 10°C to 15°C. Influent arsenic concentrations range from 0.5 mg/L to 1.5 mg/L. The ABMet® technology consistently removes arsenic to below detection limits (0.02 mg/L). Data from the full scale system will be presented, as well as regulatory requirements and site specific challenges. Keywords: Arsenic, Sulfate Reduction, Metal Sulfide Precipitate, Biological Water Treatment

Jan 1, 2005

By Jafar Safarian, Gabriella Tranell, Stine Espelien

Hydrometallurgical treatment of silicon is an effective process for the removal of metallic impurities for producing solar grade silicon feedstock. In the present research, the removal of impurities from silicon is studied through the addition of Mg into a commercial silicon, its solidi fication, and acid leaching. The effect of concentration of HCl, temperature and leaching duration on the removal of impurities are studied. It is shown that the impurities such as P, Fe, Al, Ti, Ca, …are effectively removed through the applied method and Mg improves the segregation and the removal of the impurities. Scanning electron microscopy examination of the samples indicates the disintegration and dissolution of Mg2Si phase in acid leaching which causes the chemical and physical removal of the impurities existing in the phases between the silicon grains. It is shown that the leaching process rate can be optimized through the control of the acid leaching conditions.

Mar 1, 2017

By Deepak Malhotra

Rosario Dominicana, S.A., operates a gold processing complex at Pueblo Viejo, northwest of Santo Domingo (Dominican Republic). The plant processes approximately 10,000 mtpd of oxide gold-bearing ore with a work index of 11 kWh/mt. The ore hardness has increased to about 17 kWh/mt. Metallurgical auditing of the plant was conducted? to find ways to modify the circuit to process hard ore without sacrificing throughput. In addition, unit operations were optimized to increase recovery and reduce operating cost,. The results of modifications made in the plant are discussed in this paper.

Jan 1, 1989

By M. X. Huang, Y. Z. Li

The titanium diboride (TiB2)-reinforced steel composite, designed for automotive applications, exhibits a combination of high isotropic Young’s modulus and low density as compared to existing advanced high strength steels (AHSS). The steel-based composite is produced by in situ precipitation of TiB2 particles during eutectic solidification followed by hot rolling, and its microstructure displays a homogeneous distribution of both large primary TiB2 and small eutectic TiB2 particles in the ferrite matrix. Instead of interfacial debonding, particle cracking is the primary mode of damage, revealing very high interfacial strength. To investigate the intrinsic interfacial strength, a hybrid method combining both nanoindentation and finite element analysis (FEA) was used. A micron-sized sample containing a single crystal TiB2 attached to the ferrite matrix was fabricated by focused iron beam (FIB), and was compressed using nanoindentation with a flat indentation tip. By combining the compression and FEA results, the interfacial strength was therefore determined.

Mar 1, 2017

By David G. Dixon

Although the kinetics of leaching processes are of paramount importance in the design and analysis of nearly all hydrometallurgical flowsheets, these concepts remain poorly understood and, as a result, are only rarely applied to mass and heat balance models. In this second of two papers, we demonstrate how simple yet powerful models of leaching kinetics and other rate processes may be added to mass and heat balance models, and apply these concepts using a spreadsheet model of a simplified pyrite autoclaving flowsheet. In particular, we focus on the interpretation and scale-up of batch leaching data, and on simple means for modeling other phenomena commonly associated with leaching, such as reagent depletion, gas-liquid mixing, and the precipitation of oxides and basic salts.

Jan 1, 2002

By Mim Li, Huimin Lu, Lisha Yang

"CuInS2 thin films solar cells have drawn much attention for their low-cost, stability and high conversion efficiency. The electrodeposition of Cu-In precursor films, as the first step in making CuinS2 solar cells electrochemically in the air-and water-stable ionic liquid based on choline chloride/urea eutectic mixture has been investigated at constant potential. Compared with aqueous electrolytes, the large electrochemical window as well as the high thermal stability of this ionic liquid allow the direct electrodeposition of Cu-In precursor films. Then the precursor films were sulfuretted in a tube furnace at different sulfurization temperatures to optimize the films properties. The films obtained were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS).IntroductionCuInS2 is one of the most prospective absorber materials for low cost thin film solar cells, with a high conversion efficiency that exceeds 32% in terms of theory and nearly 13% in laboratory level [1-2]. In addition to its long-term stability, CuinS2 has a band gap energy Eg ranging from 1.3 to 1.55 eV and an optimal optical absorption coefficient reaching 105cm-1 [3-4]. CuinS2 thin films have been prepared by several methods such as spray pyrolysis [5-6], r.f.sputtering [7], vacuum evaporation [8-9] and electrodeposition. Comparing with vacuum methods, electrodeposition has lots of advantages such as less energy consumption, preparation big area thin film, stable system and enabling cheaper films.The electrodeposition of most technologically important metals has been shown to be possible from a wide range of ionic liquids. These ionic liquids are currently applied in a wide variety area. It is reported that the cell efficiency of chalcopyrite absorber layer (CIS, CISeS, and CIGS) via an electrodeposition route in laboratory condition has reached 11.3% [10]. Copper and indium alloy film is regarded as important precursor for the production of compound semiconductors with sulfur. The electrodeposition of the alloy film from room temperature ionic liquid (RTIL) has not been widely investigated. Only few alloy films, such as ZnTe, CdTe, GaAs and AlSb have been electrodeposited."

Jan 1, 2011

By Ari I. Kogut

Impurity minerals in fluorspar ores and concentrates from a deposit in Southern Africa have been studied by reflected light, transmitted light, and cathodoluminescence microscopy. The principal impurities are quartz, calcite, aegirine, apatite, ankerite, magnetite, goethite, and synchysite [Ca(La,Ce,Nd)(C03l2Fj. Cathodoluminescence microscopy was found to be very useful in studying the character of the fluorite and especially for recognizing the presence of apatite and calcite impurities. Fluorite exhibits blue, calcite shows yellow, and apatite has white, light purple, and pink cathodoluminescence. The cathodoluminescent character of apatite varies with its geological environment and position in the orebody. The results of this microscopic study show that phosphorus present in flUorite concentrates occurs principally in binary locked apatite-fluorite particles. Successive fluorite cleaner concentrates contain progressively smaller amounts of locked apatite-fluorite particles. Free apatite has been effectively partitioned to the final tailings.

Jan 1, 1995

In the new flowsheet for Inco Limited's S02, Abatement Project at the Copper Cliff, Ontario operations, a copper/nickel sulphide flotation concentrate will be flash smelted, then converted to Bessemer matte. As in current practice, this will be slow-cooled and separated into components by magnetic separation and flotation. The copper content will emerge as a chalcocite concentrate (impure Cu2S), containing some nickel. This copper sulphide will be converted to copper metal.

Jan 1, 1993

By Shi Guan-Yong, Niu Li-Ping, Dou Zhi-He

"In the preset work, the viscosity model (named modified KTH model) proposed by Sichen Du and S. Seetharaman et al and extended by Shu Qi-feng was applied to the ESR slag systems. A correlation to predict the viscosities of CaF 2-(CaO)-Al203 slags using interaction coefficients of different cations in the presence of oz-and viscosity interaction coefficients between oz-and F in the presence of different cations has been developed. The interaction coefficient between oz- and F- in the presence of Al3+ was determined from the experimental data as shown in known literatures. The good agreement between the calculated viscosities and the experimental data in the CaF2-(CaO)-Al203 systems has indicated that this approach can be successfully employed to predict the viscosities of ESR slags.IntroductionReliable viscosities data of high-temperature slag melts are important for the modeling and design of high temperature metallurgical processes. Although a number of experimental measurements have been carried out, the available viscosities data is still scarce compared to the needs of today's technology, especially in the case of complex melts. In process simulations, the needs of viscosity descriptions for complex systems which could enable the extrapolation of the data as functions of temperature and composition is strongly felt today."

Jan 1, 2013

By Pei-xiao Liu, Han-jie Guo, Yan-xiang Li

The thermodynamic analysis on chromium ore pellets in solid reduction chromium process is carried out, and the result is validated by pre-reduction experiment of cold briquetted chromium ore. Polarization Microscope and SEM are employed to observe microstructure and element composition. The thermodynamic and experimental results reveal the reduction mechanisms at different temperatures in the SRC pre-reduction process.

Mar 1, 2017

By I. Kim, J. C. Choi, W. D. Cho

"The effect of yttrium addition on the oxidation behavior of Fe3Al intermetallic compound was investigated in the range of temperature 800 to 1100 °C in 0.2 atm 02 in terms of oxidation rate and oxide adhesion. The oxidation rate of alloys, Fe-14.3 wt% Al and Fe-14.1 wt% Al-0.3 wt% Y, was nearly identical and the parabolic rate constant calculated as a function of temperature is Kp=5128 exp[-39506(cal/mol)/RT] mg2/cm4 hr.Rapid cooling and ultrasonic stress tests were carried out to test adhesion of scale formed on the alloys. While the oxide layer formed on the Fe-Al alloy without Y was found to be fragile and detached easily during the tests, the oxide layer formed on the Fe-Al alloy containing Y was protective, dense, and adhesive. The following two mechanisms were proposed to explain the adhesion improvement of Ah03 formed on the Fe3Al containing yttrium : (1) the addition of yttrium decrease generation of growth stress in alumina scale because the preferential diffusion of yttrium through grain boundary in alumina scale prevent internal oxidation of Al, one of main causes of growth stress, and (2) the second phase formed on the oxide scales prevents crack propagation through the scales, leading to better mechanical stability of the oxide scales.IntroductionIron aluminides have attracted the attention of many researchers as a candidate for use at high temperature because of their excellent oxidation resistance due to the formation of protective alumina scale. In order to resist aggressive environments at elevated temperatures, oxide scale formed on iron-uluminum alloy must satisfy the following three requirements : (1) thermodynamic stability (2) slow growth rate (3) adherence on substrate. According to Wallwork and Hed [l], the most suitable alloys for high temperature application are Fe, Ni, and Co alloys with the protection of Si02, Cr203, and Ah03 scales. While chromium oxide can vaporize as Cr03 above 1000 °C and silicon oxide may form low melting silicate [2,3], Alz03 has a high melting point and is the most stable among the three oxides thermodynamically [6]. In this respect, iron aluminides forming alumina seem to be most suitable for use at high temperature. However, alumina scale formed on the iron aluminum alloys tends to be easily spalled during oxidation due to the combination of growth stress and thermal stress."

Jan 1, 1998

By Yungang Li, Hui Li, Ramana G. Reddy, Jinglong Liang

High solid corrosion protective coatings were prepared by the dust of the converter with an average particle size of 59.33 μm. The effect of different amount of benzyl alcohol diluent on the performance of high solid anti-corrosion coatings was studied. With the increase of the amount of diluent, the viscosity of high solid anti-corrosion coatings reducing, the film apparent bubble content decreasing, and film resistant to salt water corrosion ability decreased, while acid corrosion capacity enhancement. When the dosage of diluents is 15%, the coating film is more resistant to acid corrosion.

Mar 1, 2017

By Xueming Lv, Xuewei Lv, Jie Qiu, Lunwei Wang

Non-isothermal multiple scanning rate analysis method was used to analyse the solid-state reduction of nickel laterite by carbon. According to the TG curves, the activation energies were calculated and the most probable mechanism functions were determined by the Malek method. The results show that the process can be divided into three stages according to the reaction degree (a): 0–40%, 40–70%, 70–100%, respectively. In the stage of 0 a 0.40, the most probable mechanism function fits the chemical reaction order function. In the stage of 0.40 a 0.70 and 0.70 a 1.0, the process may not be exactly described by one mechanism function.

Mar 1, 2017

By Antonio Huerta

The effects of potassium ethyl xanthate collector and potassium dichromate used as a depressor on a PbS mineral were studied by high frequency impedance technique. Measurements of complex permittivity, at 100 MHz suggested that is possible to obtain from isotherm adsorption the adequate industrial collector concentration being this in the range of lE-3 to 5E-3M of KEX. The e' values (320-420) in the PbS-KEX system was increased as the KEX concentration was lowered). In the other hand the PbS- K2Cr2O7 system showed higher values of e' (420-510) as the K2Cr2O7 concentration was increased. The PbS-KEX-K2Cr2O7 system was evaluated.

Jan 1, 1997

By Yijia Dong, Mingjun Rao, Pengxu Cao, Jun Luo, Guanghui Li, Zhiwei Peng

Coal fly ash (CFA), as a by-product generated from coal fired power stations, is widely used for autoclaved concrete block production. It has been found that the generation of tobermorite is great benefit to the block strength during autoclaving. In this study, the tobermorite fibers synthesized from CFA and lime via the hydrothermal process are used as the revulsive to promote the mechanic strength of the concrete blocks. The results show that tobermorite fibers with 0.01–0.5 lm in diameter and 1–3 lm in length are obtained at 200 °C for 0.2 h. As the addition of prepared tobermorite fibers increases from 0 wt% to 2.0 wt%, the compression strength of concrete block increases from 24.6 to 40.5 MPa, and the compression strength of aerated concrete block produced under the optimized conditions can reach above 7.5 MPa.

Mar 1, 2018