Search Documents

By Susumu Okabe

Top blowing lances are employed by the Mitsubishi Continuous Copper Converter for the continuous supply Of reaction gases into moken bath. In order to minimize the refractory wear caused by the interaction between the furnace lining and the melt splash. optimum furnace design and blowing condition are? required. An empirical equation obtained by the physical model study enables the estimation of the splashing rate on a vel1ical plane at a certain distance from the lance.

Jan 1, 1996

By J. Markussen

The Falconbridge Matte Leach Plant was based on leaching Ni-Cu matte with strong hydrochloric acid in rubber lined equipment. It operated from 1968 to 1983 as a precursor to Nikkelverk's present C12 Leach. The process comprised two S.X. systems. NiC12.4H20 crystallization, crystal drying, NiC12.H20 pyrohydrolysis and HC1 gas recovery. The naphtha fired fluid bed pyrohydrolyzer produced granular NiO, subsequently reduced with H2 to granular nickel for sale. The development and operation of the pyrohydrolyzer are described

Jan 1, 1991

By M. Hashimoto

The equilibrium distribution ratios of sulfur between molten copper and CaO-fluxes containing caF2 and caC12 were determined in the range of 1300° to 1400° C under carbon monoxide. The rate of approach to equilibrium is rapid and increases with increasing CaCll concentration. In CaO-CaFl-CaCl2 fluxes, the distribution ratio varies in a complex way with temperature and CaFl concentration. The results are compared with those obtained with the binary fluxes of CaO with BaFZ and MgFl ?

Jan 1, 1983

By R. Kramer

During foundry sand reclamation process development, molds formed from reclaimed chromite sand showed a rapid decline in tensile strength during thermal cycling tests. Because this characteristic could limit reuse of chromite sand in the. foundry, the sand was examined in detail Scanning electron microscopy, x-ray mapping, magnetic susceptibility, and x-ray diffraction were utilized to evaluate processed chromite sand. It was found that process variables such as binder composition, reclamation temperature, and processing method had a significant effect on the chromite sand particle surface. X-ray diffraction indicated a crystallographic change in the processed sands. Magnetic susceptibility also increased after processing. Diffusion of iron to the particle surface and increased surface roughness were identified as potential causes of the decreased tensile strength in the molds.

Jan 1, 1991

By G. White

Traditional atmospheres used for Aluminum annealing have been air, exothermic gas, and cryogenic purity Nitrogen. Air and exothermic gas have several problems associated with them such as surface discoloration, toxic emissions, and explosion hazards. High Oxygen levels can cause Magnesium streaking and oil staining, and therefore pure Nitrogen has been the atmosphere of choice for high quality Aluminum coils. A comparative study was made on key Aluminum alloys annealed in Nitrogen with different Oxygen concentrations to determine the effect on surface quality. The atmosphere composition inside the furnace was analyzed during the purge and heat cycle to determine its effects on purge times and exhaust emissions. The Aluminum coils after annealing were visually inspected for surface staining before and after rolling. The lab study revealed that Nitrogen with up to 1.0% Oxygen is acceptable, and did not adversely effects the surface quality or any of the other processing variables. However it isbelieved that higher Oxygen concentrations are acceptable depending on the rolling oils and alloy systems.

Jan 1, 1996

By Laurent Cohen

Since the 1970s, Solvent Extraction (SX) in hydrometallurgical processes has been a key enabling technology in the production of high-purity metals. Examples include copper, rare earth oxides, uranium, cobalt and nickel. Notwithstanding incremental improvements in extractant formulations, few breakthroughs can be recounted in this industry outside of the initial amine-, oxime- or phosphine-based reagent chemistries. However, the advent of lithium-ion batteries and their stringent requirements for critical materials (lithium, cobalt and nickel) offer new challenges and opportunities for SX. Solvay recently introduced a new extractant for lithium, CYANEX® 936, and developed unique modeling software capabilities in cobalt/nickel separation using CYANEX® 272, zinc SX using DEHPA® and rare earth separations using CYANEX® 572. This paper discusses trends in SX and provides insight on processing of critical materials essential to energy sources. It also summarizes the technical and economic benefits based on extractant selection and advances in modeling.

By Zhanjun Wang, Yongqi Sun, Mei Zhang, Zuotai Zhang, Min Guo

The role of fluorine on the viscous and crystallization behavior of CaO-SiO2-MgO-Al2O3-FetO-P2O5-(CaF2) slags were explored using the rotating cylinder method, non-isothermal differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. It was found that the viscosity slightly decreased with increasing CaF2 content. It was also found that CaF2 addition can promote the primary phase transformed from MgFe2O4 spinel to Ca3(PO4)F, which was beneficial to the enrichment of phosphorus. Additionally, the structure of the slags explained by X-ray photoelectron spectroscopy (XPS) and magic angular spinning nuclear magnetic resonance (MAS-NMR) were further analyzed, which was well in accordance with the above analysis.

Jan 1, 2016

By H. Y. Sohn, Haitao Wang, Moo Eob Choi

"A novel ironmaking technology is under development at the University of Utah. This technology produces iron directly from iron ore concentrate by gas-solid suspension reduction. Hydrogen is the main reducing agent for high reactivity and for the elimination of carbon dioxide release in this ironmaking process. The direct use of concentrates allows bypassing the problematic pelletization/sintering and cokemaking steps in the steel industry.Intrinsic kinetics of the suspension reduction of magnetite concentrate particles by hydrogen has been measured. Experiments were carried out in the temperature range of 1423-1673 K, other experimental variable being hydrogen partial pressure, the amount of excess hydrogen and particle size. Under most experimental conditions, 95% reduction was attained within several seconds, which presents sufficiently rapid kinetics for a suspension reduction process. The reaction kinetics followed the nucleation-and-growth equation, and a rate equation that contains all the effects of the experimental parameters has been obtained.IntroductionWith the rapid increase in steel production, it is critical to control CO2 emissions which is the main greenhouse gas. It is inevitable to release a huge amount of CO2 when coke and/or coal are used as the main reducing agent in producing iron. As one of the methods to reduce the CO2 emission from ironmaking, the utilization of the gaseous reducing agents and fuels, including hydrogen, has been investigated [1-6]. The use of such gases forms the basis for a new ironmaking technology under development for producing iron directly from fine concentrates by a gas-solid suspension technology. This technology would reduce energy consumption by about 40% of the amount required by the blast furnace and drastically lower environmental pollution, especially CO2 emission, from the steel industry [4]. This is accomplished by adopting H2-based reductant and bypassing pelletization/sintering and cokemaking steps. Unlike other gas-based alternative ironmaking processes using shaft furnaces or fluidized-bed reactors, the suspension reduction technology is a high-intensity process because it will not suffer from the problems that other processes do when operated at high temperatures mainly from the sticking and fusion of particles."

Jan 1, 2011

By Ko-ichiro Ohno

It is recently recognized that the iron reduction and melting as well as the slag separation of a composite of granular iron ore and coal are completed in a very short period of about 10 minutes when the composite is rapidly heated up to approximately 1673K. These phenomena are expected to be applied to a new iron-making process. The mechanism of iron ore reduction and iron-slag separation during rapid heating has not yet been revealed and the fundamental research has just started. Carburization of the reduced iron is regarded as one of the most important steps in this process. In the present work, the composite was prepared from four kinds of coal or graphite as a carbon source and electrolytic iron powder as a completely reduced iron ore. The temperature at which the liquid formation and iron carburization occurred was monitored. Direct observation of smelting reduction behavior was made by a confocal laser-scanning microscope combined with the infrared image-heating furnace to clarify the effect of molten ash on iron carburization. It was found that the meltdown temperature of composite became lower as the melting temperature of coal ash decreased. From the observed result, it was presumed that the liquid slag would act as an important media for the carbon transfer from coal to iron. The carburization mechanism during the smelting reduction was estimated as follows. When slag containing iron oxide melted down and contacted carbon, iron oxide in the slag was reduced and the formation of the metallic iron particle as well as the its carburization occurred simultaneously at the slag-carbon interface. Carburized iron particle was carried from slag-carbon to slag-iron interfaces due to the slag convection flow caused by the difference of the interfacial tension between the carbon-slag and iron-slag interfaces. Carburization of reduced iron could proceed with a repeat of the above-mentioned process.

Jan 1, 2003

By I. U. Onyenanu, C. E. Ilochonwu, E. I. Nwonye, C. O. Nwajagu

This work shows how pure silica was derived directly from rice husks ash (RHA) in different temperatures for reduction to Silicon (Si). The processes to form Si materials are usually complex, costly and energy-intensive. The silica in the ash undergoes structural transformations depending on the conditions of combustion. A high purity silica was produced at 650oC after burning the rice husk (RH) for up to 7 hours. The purity of the silica was determined by dissolving the RHA with alkali solution to form sodium silicate solution of pH 11.0. This was added to hydrochloric acid of pH 1.5 which lowered the pH of the solution to 4.0 to form silica gels. The silica gels produced were washed and dried to powder and then characterized using XRD and EDX techniques. This study was done to reduce energy waste and environmental pollution in Nigeria as silica is used to develop many materials.

Jan 1, 2015

By Juan H. Rojas C.

The Chuquicamata mining and metallurgical complex is the main Division belonging to Corporation Nacional del Cobre de Chile (CODELCO-CHILE) and it accounts for 50% of the 1.4 Mt of fine copper output of the Corporation. It has been producing copper since 1915. The paper refers to the challenges that Chuquicamata has to solve in the near future. These challenges are: the increasing operation costs associated to a 800 m depth pit with low prices in an overstocked copper market; the increasing people's sensitivity to environmental preservation; and, the transformation needed for achieving high levels of organizational effectiveness. According to Corporate policy, Chuquicamata is making efforts to switch from a management style focused on supply to a management style focused on demand side of the industry. In this direction is tempting to establish strategic alliances to develop both new copper products and uses, to rise the metal demand. In more than 80 years of operation, Chuquicamata had exploited just one third of its geological resources. The exploitation of the remaining two third is a huge engineering challenge, taking into account the depth of the deposit, the impurities content, the decreasing ore grades and the transportation distances for waste dumping. All those factors are relevant in the economical process of transforming geological resources into ore reserves. Chuquicamata has other limitations. First, a 20,000 people town just aside the pit that limits the mining rates because of dust generation; second the scarceness of water in the desert area where Chuquicamata deposit is located; and, finally, the new tailing pond is a problem which solution will demand huge engineering efforts and investments. People are the principal factor associated to a company success. In this field, Chuquicamata have been progressing, but much more efforts from people will be necessary to reduce production costs for being successful as any other price-taker within the copper industry. Chuquicamata must develop the skills of its Supervisors to transform them into leaders and entrepreneurs, who additionally have the challenge of passing on their knowledge to non-professional workers. It is an ethic commitment to assure personal and professional growth of workers, as the only sustainable way to get real and integral success.

Jan 1, 1999

By Kang Wan, Lei Tang, Jianchao Li, Jieyu Zhang, Minqi Sheng, Jifang Xu

"The viscous flow phenomenon in slag close to the liquidus temperature was considered. A simple approach that liquidus temperatures of melt could be derived from viscosity data was employed. The potential of this method for estimating the liquidus temperatures of pure water and binary alloy was demonstrated. The liquidus temperatures of the CaO-Alz03 based slags obtained from the second derivative method depends upon the number of viscosity values available at different temperature intervals. The results indicated that plots start deviating from the straight-line behavior at temperature as expect, and the second derivatives show the break points at a certain temperature, which is the liquidus temperature. Comparisons among the present observations as well as the characteristic temperature of the selected slags, which measured by the hemisphere method and DSC, indicated that it is possible to get a reasonable idea of estimate the liquidus temperatures from activation energies for viscous flow.IntroductionThe liquidus temperature of slag, which has a significant effect on the kinetics of chemical reactions and the slag-metal separation, is extremely important for metallurgical operations. Experimental measurements of the liquidus temperatures of slags are difficult, since slags invariable supercool. In addition, behavior of a single constituent in a multi-component slag is different in different circumstances due to its interaction with other constituents. Hence, it is essential to study the liquidus temperature of each particular slag resulting from a special process. Usually, the compositions of the slags aimed to the single liquid region of the phase diagram. However, the phase diagram of many slag systems, which back often to the 1950's, involves considerable uncertainties. Many liquidus temperatures are given as dotted lines in Slag Atlas [1]. Disagreements between the phase diagram and the reality have been found [2]."

Jan 1, 2013

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"The use of electromagnetic field to remove suspended particles from metals such as aluminum by pushing to the boundary has been well studied. However, the potential of this method is yet to be exploited for the removal of inclusions from silicon. Considering the increasing amount of Top-cut SoG-Si scraps year upon year, there is the need to harness all the potentials of technologies to recycle this materials to ensure sustainability. This study investigates, and discusses new results on the effect of processing parameters such as composition, coil current, and frequency on the removal of inclusions from silicon under high frequency AC electromagnetic field.IntroductionThe solar cell silicon making industry requires pure and clean silicon in order to maximize the conversion potential of the solar cell material. The conversion efficiency of solar cells is limited by minority carrier recombination at dislocations and those intra-granular defects such as impurities, small clusters of atoms, or precipitates [1]. Recent global developments in the energy sector with a drive for the production of clean, reliable, and affordable energy have stirred a rapid growth in the production of photovoltaic (PV) cells.[2] Thus over the years, silicon based PV cells has seen a lot of growth as it has a PV market share of over 90 % [3] either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [4]. MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from the air absorption during solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [5]. For sustainability the silicon in the top-cut silicon scraps must be recovered. Therefore methods for removing non-metallic particles, such as SiC and Si3N4, from the silicon are important in order to recycle the top-cut scraps to a useful feedstock for the silicon solar cells manufacturing."

Jan 1, 2012

By J. M. Toguri

The viscosity of the molten FeO-Fe2O3-Si0z system in the composition range of interest to copper smelting has been investigated using a rotating cylinder technique. The silica content of the slag was varied from 20 to 35 wt percent while the oxygen pressure of the system was varied from 10-7 10-11 atm. The temperature range investigated was from 1200 to 1350°C. It was found that the viscosity of the slag generally decreased with increasing temperature and increasing oxygen pressure. As the silica content was increased, the viscosity was found to increase.

Jan 1, 1976

By Susanne Pignolet-Brandom

Reflected light microscopy scanning electron microscope energy dispersive spectroscopic analysis and backscatter electron image and electron microprobe chemical analysis have been used to study lead sinter and lead blast furnace slag. These studies provide invaluable information on the phases present their intergrowths, and their chemical composition. Such information increases the understanding of the nature of pyrometallurgical processes and the behavior of minor elements during these metallurgical processes.

Jan 1, 1987

By J. R. Donald

Surface and interfacial phenomena play a significant role in refractory performance. For example, the wettability of the refractory material with slag, matte, and metal influences infiltration and interfacial reactions. Yet, very little fundamental information regarding the surface properties of refractory materials and slag is available. Thus, in the present work, the sessile drop technique incorporating a high temperature furnace equipped with X-ray fluorescope was employed to investigate the surface and interfacial phenomena of fayalite-type slags on solid alumina at 1200?C. The iron to silica (Fe/SiO,) ratios employed were 1.4 and 2.0, and the oxygen potentials used were log p02 =-11 and log p02=-9 atmospheres. The contact angle between the fayalite-type slags and the alumina were determined to be relatively low, at about 16.9 to 19.6 degrees under the experimental conditions. The surface tension of fayalite slag (Fe/SiO2=1.4) at an oxygen potential of log -11 was 0.298, which agreed with the work of previous researchers. The surface tension of the fayalite was observed to increase with time. The spinel FeAl2O4. was determined to be the product of the interfacial reaction, and 8.8 to 15.8 mass percent alumina was dissolved into the slag after 40 minutes.

Jan 1, 1996

By Kiichiro Hayashi

"Indonesia is one of the world leaders in palm oil production. Palm oil industry is an industry to be considered when it comes to environmental impacts. This paper utilizes three step approaches. First, a material flow analysis of palm oil related industry was conducted in Indonesia. Second, a factory visit survey was conducted for getting information on environmental impacts of plantation and CPO mills. Third, a LCA study was made for a model Indonesian CPO mill in several bio-waste treatment options. Main findings were that, first; over 70% of FFB was bio-wastes generated from CPO mills. Second, some mills introduced a zero emission bio-waste policy. However, untreated bio-wastes in the zero emission policy, such as, CH4 from POME ponds, may have potential to reduce more impacts on the environment. Introduction Indonesia is one of the world leaders in palm oil production with approximately 12.4 million tons of crude palm oil (CPO) production in 2005 and with the plantation area 5.6 million ha spreading out in 19 provinces [10]. The expansion of palm oil cultivation in Indonesia and its export oriented industry heavily relies on the strong world market demand for food. Currently, there are 320 CPO industries in Indonesia [10]. These include plantations and palm oil related factories. Among them, there are six biggest players in CPO business in Indonesia: PT. Perkebunan Nusantara (PTPN) consisting of 9 PTPN, Sinar Mas, Raja Garuda Mas, Astra Agro Lestari, Minamas Plantation and Indofood. They are managing more than 50% of plantation estate in Indonesia and are leading the Indonesian palm oil business.Palm oil industry is an industry to be considered when it comes to environmental impacts. Unfortunately, there is not so much available information related to the performance of each CPO on environmental impacts. There are reports which provide information on environmental impacts of CPO mills in South East Asian countries, but are limited to, for instance, Thailand’s cases [4 and 5] and Malaysia’s cases [1, 3, 6, 7, 9, 11 and 12]. On the other hand, similar studies on the Indonesian’s case are not well established in academic literatures. And also there is limitation on Indonesian palm oil industrial information from plantation to consumption and disposal in academic articles. There is no literature related to material flow analysis focusing on the whole Indonesian palm oil related industry. One way to describe and present the environmental impacts is through a life cycle assessment (LCA). The LCA could be used to estimate the impacts of CPO production including the stages of plantation, transportation and milling [5, 8 and 11]. However, studies on Indonesian CPO production process were not well established in academic articles. The purpose of this paper is thus to clarify environmental impacts of palm oil industry in Indonesia especially by focusing on plantation and CPO mills with consideration to various bio-waste treatments."

Jan 1, 2008

By Takashi Nakamura

Dismantling and detachment of parts from e-scrap are essential and involve higher cost techniques in pretreatment processes for physical separation. New techniques are desired for effective recycling of minor rare metals, therefore, we are trying to develop new detachment processes such as a new break down process. The principal of this new process is an electrical disintegration by electric pulse. E-scrap is broken down by high voltage electric pulses in water. IC chips and LSI can be detached from printed circuit boards under proper conditions. Ta- capacitors are also broken down to plastic parts and Ta sinter with lead wire. This is very useful in terms of pretreatment for e-scrap recycling. Also in the case of metallurgical production, with its intrinsic potential of smelting, extraction, enrichment and separation methods, play an important role in the context of minor rare metals.

Jan 1, 2015

By Bogidar Mihaylov

A laboratory study was conducted on continuous precipitation of copper, cadmium, mercury and arsenic using thiourea, thioacetamide, sodium sulfide and ammonium sulfide as precipitating agents. Depending on the experimental conditions the metals precipitate with the sulfide donors at different orders and rates. These differences were employed as a basis of several techniques for continuous separation of copper and arsenic, cadmium and arsenic, mercury and copper, and copper, mercury and arsenic. The separation of the metals from industrial waste solutions was also studied. The precipitates obtained were inspected using x-ray diffraction, scanning electron microscope, atomic absorption spectrometer and plasma particle counter.

Jan 1, 1992

By Liang Li

Thermodynamic analysis and experiments were conducted in order to verify the feasibility of preparing crude titanium tetrachloride (TiCl4) via the carbochlorination of low-grade titanium slag in molten salt. Titanium slag, assaying 74.6 wt% TiO2 with high calcium and magnesium oxide impurities, was treated by an optimized carbochlorination process in NaCl molten salt. These impurities in the titanium slag were chloridized simultaneously, and chlorination products FeCl2, MnCl2, MgCl2, CaCl2 and CrCl3 were collected in the furnace slag. XRD and SEM/ EDS analysis of residue shown that SiO2 and Al2O3 in titanium slag were difficult to chlorinate completely. Theoretical calculations and industrial-scale experimental studies reveal the content of TiCl4 in the products was more than 98.8 wt% and thus proved the feasibility of utilizing low-grade titanium slag for TiCl4 preparation by molten salt chlorination technology.