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By Takeshi Yoshikawa

For the development of low-cost silicon refining process for solar cells, the present authors have been studying the low temperature refining technique, ?solidification refining of Si with Si-Al melts at 1173 ? 1273K?. In the present work, we have investigated the B removal in that refining, utilizing the segregation effect and also the effect of Ti addition to the melt. Segregation ratio of B between solid Si and Si-Al melt was measured by the temperature gradient zone melting technique and it indicated the B removal fraction would be as much as 90%. Titanium addition to the melt was found to produce the TiB2 precipitation with soluble B in that melt and bring the effective B removal of refined Si to its content of 1ppma.

Jan 1, 2006

By O. M. G. Newman

Research into potential applications of spouted bed electrowinning (SBE) in the zinc industry was conducted, in a collaboration between our two organizations. The main system investigated was zinc from acidic sulfate electrolytes. However, SBE can be extended to other electrolytes, or recovery of other elements. Electrolytic tests were carried out at the 0.01 to 0.1 m2 scale. Spouting behaviour has been studied at a larger scale, approaching a size suitable for an industrial unit cell. Much of our work was carried out using a micro-porous separator (Daramic®). However, we have also shown that ion exchange properties can have a controlling effect on the process chemistry, electrochemical efficiency, and plant flowsheet. In initial 0.1 m2 scale electrolytic tests, design and engineering issues for scale-up were identified. We review the major achievements, promising areas for application in the zinc industry, current status, and remaining barriers to development of SBE technology.

Jan 1, 2003

By John D. Kinton

A patent is a right granted by the government to exclude others from making, using, selling, offering to sell, or importing a claimed invention. Once the right is granted, the patentee may use the U.S. Federal Courts to enforce that right. Reading a patent from a litigation perspective is quite different than reading it from a technical perspective. The Judge's interpretation of the claims will affect their scope, and likely the ultimate outcome of a patent case. Additionally, the patent right can be challenged. If done successfully, the patent can be rendered invalid or unenforceable. The likelihood of success, and well as the achievement of other litigation goals is often influenced by the forum where the litigation is initiated. Finally, patent litigation costs are significant, and will weigh heavily in the decision to file (or fight) a patent lawsuit.

Jan 1, 2006

By Roberto Parra

The wear and corrosion phenomena in the furnace lining of the ferrous and non ferrous pyrometallurgical processes are complex problems where chemical, interfacial and mechanical phenomena are presents. The characteristics of the processes determine the conditions to which these materials are submitted, where the thermal conditions reached during the operation is one of the most important parameter. Assuming that all the degradation phenomena are thermal activated, the rate of the different steps of the wear mechanism will depend on the thermal field in the lining. In view to apply the independent physicochemical knowledge of degradation mechanisms to the analysis and design of furnace lining the methodology of the Nodal Wear Model (NWM) was done. It combines the mathematical modelling of the heat transfer in the lining with the physicochemical control equation for the wear-corrosion phenomena. The NWM has been applied to different examples: theoretical analysis, laboratory scale test and industrial applications. We present in this paper the theoretical background of the model and two examples of applications: the sole of an electric furnace and the earth of a blast furnace.

Jan 1, 2006

By Michael L. Free

Bacterial oxidation of an arsenopyritic gold-ore .concentrate was carried out with continuous-flow .operation in 14-liter, mechanically agitated reactors. Samples from the slurry reactors were separated into solid and liquid fractions and analyzed separately to determine the electrochemical rates of sulfide conversion by the bacteria and the rates of direct bacterial oxidation of sulfide. The rates of the individual mechanisms are compared to the overall rates of biooxidation in the continuous-flow slurry reactors. The results show that the commonly hypothesize4 direct and indirect mechanisms of biooxidation both play a significant role in the bacterial oxidation of sulfide ores.

Jan 1, 1991

By Kazuyo Yokoyama

New environmental assessment model based on the Waste Input-Output analysis has been developed and applied for the "Landfill mining activity". "Landfill mining" implies the digging up of the landfilled wastes, the recovery of valuable material and energy resources and, thus, the reuse of the saved space as a new landfill site. In this study, the landfilled wastes are assumed to be treated by the gasification/melting processes. Two kinds of reactors, the fluidized bed type (FB) and the shaft furnace type (SF), have been considered in this work as the typical gasification/melting processes adopted in Japan. In FB, the dug-up wastes are heated in the sand fluidized bed zone under reducing atmosphere, Fe and Al are recovered in the metallic form, and then, the gasification/melting of residues is made in the second zone. In SF, the waste is charged in the high temperature coke bed, and the gas is recovered together with molten metal and slag. Both processes generate electric power by the recovered heat and fly ash as waste to landfill. It has been found in this study that the both processes can reduce the total volume of waste and save the available landfill space. SF seems to have higher potential for decreasing volume of wastes because of less emission than FB while FB has great benefit to recover metallic Fe and Al individually. The results of scenario analysis have also indicated that the landfill mining activity is effective for sustainable management of landfill sites.

Jan 1, 2006

By Raj P. Singh

Lewatit TP207, a chelating resin with iminodiacetate functional group, is used for the purification of cobalt hexammine chloride solution for divalent cationic impurities (US Patent No. 5,154,757). The method is employed at commercial scale in OSRAM SYLVANIA Inc. cobalt chemical production since 1992. It is observed that after long use in the purification of cobalt hexammine chloride solution, a large number of resin beads tum black from their original beige color. The purpose of this paper was to characterize these black-colored resin beads for their ion exchange behavior. The resin sample used in this work was an exhausted production TP207 resin containing large number of black-colored beads. The results indicated that blackened resin beads can be regenerated to almost full capacity and' their ion exchange behavior for the purification of cobalt hexammine chloride solution was comparable to the new resin.

Jan 1, 2001

By Thomas Niehoff

Many industrial processes require energy. Energy is required for melting or heating purposes. The heat can be generated by electrical heating or combustion/oxidation of hydrocarbons. Oxygen supports the combustion process. Oxygen is naturally contained in air with about 21 vol.-percent. The use of technical oxygen will allow an increase to the natural oxygen concentration of combustion air. Altering the combustion process by increasing the oxygen content has various effects. These effects are described and analyzed with regard to heat transfer, emissions and energy consumption. Industrial processes requiring oxyfuel are described and discussed regarding energy aspects.

Jan 1, 2008

By R. Ghisleni, R. E. G. Bohrer, L. Radtke, R. M. C. Santana

"The major source of environmental pollution in urban areas is the transport sector and its impact on human health and the greenhouse is preoccupying. In many works of literature is monitored the pollutants in urban cities, however in specific areas such as universities, they are scarce. Therefore, the aim of this work is to monitorate the gaseous pollutans in a bus terminal at Santa Cruz do Sul University-UNISC and to develop a control framework of the air quality. Six points were selected for monitoring, being one of them inside a bus. The monitoring of CO, HC and CO2 were carried out on arrival and departure of the bus. Preliminary results conducted in a day of spring showed that the most critical condition was during the night shift, where the concentration of CO (200 ppm) was the highest, caused by the vehicles increase, due to the larger number of students.IntroductionThe first major global assessment of climate change science in six years has concluded that changes in the atmosphere, the oceans and glaciers and ice caps show unequivocally that the world is warming. The report released on February 2, 2007, the first of four volumes to be released this year by the IPCC, also confirms that the marked increase in atmospheric concentrations of greenhouse gases is the result of human activities.The transport sector has become by far major source of environmental pollution in urban areas. The continual traffic growth has raised concerns over the impact of traffic emissions on human health and urban environmental quality, and has fuelled the demand for a coherent regulatory framework for the management of traffic, air quality and emission at urban level, as well as at regional and national scales.In Greater Metropolitan São Paulo, Brazil, fossil fuel combustion in the transportation system is a major cause of outdoor air pollution (Miraglia&El Kouri, 2007). In China several studies on gaseous emissions are being conducted by F. Costabile&Alegrini, (2007), developed a study on the pollutants in the city of Beijing suggesting methods for the control of pollution.The results obtained from the estimation of the atmospheric pollutants emitted monthly in Campo Grande/MS, Brazil, by buses and minibuses, which employ diesel, biodiesel or natural gas as fuels showed that the substitution of diesel by biodiesel would diminish the emissions of pollutants (Kozerski&Hess, 2006)."

Jan 1, 2008

By K. S. Kumar

FLS miljø, Inc. markets, designs and supplies particulate collection devices for dusts, fumes, and mists; In this paper, the application of both wet and dry electrostatic precipitators (ESPs) in smelting, and roasting plants is discussed.

Jan 1, 1998

By Richard P. Roberts

This paper will discuss the methods for the cooling of aluminum melting furnace? dross .and their impact on the environment. Also discussed will be a case history of an AROS Dross Processor installation, which is designed to maximize the recovery of metal content of the dross in a manner which is not only environmentally cleaner, but which also prepares the output in such a way as to facilitate downstream processes. Handling of the discharged material will be discussed in regards to the recycling of the preserved metal content and deposition of the unusable-materials.

Jan 1, 1992

By Laura Garcia H, Juan Carlos Gonzalez Islas, Luis Garcia Lechuga, Pedro Alberto Ramirez Ortega

"Electrochemical studies were performed to silver recovery from industrial wastes (radiographic films) on litanium flat electrode using a filter press-type electrochemical reactor with vertical orientation (known as REOV-01), as counter electrode was used a mesh-type DSA. Voltammetric studies were employed to fmd the current range under which silver reduction occurs. Using chronopotentiometric studies with controlled current, homogeneous deposits were obtained on the surface of the Ti electrode, to a current of -210 mA during 120 minutes to a constant linear flow velocity of 15 Lmin-1 was achieved 97% of silver recovery from industrial wastes. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy studies corroborated the presence of silver on Ti flat electrode. In addition, the silver concentration in the solution after the experiments was 1 ppm below environmental requirements. This indicates the viability of a filter press-type electrochemical reactor with vertical orientation (REOV-01) for silver recovery from radiographic filmsIntroductionIn recent years, the industrial sector has shown an increase in the use of silver due to new applications in different areas. In sectors such as photography, the consumption of silver has declined as a result of the boom in digital photography. However, the use of silver in radiographic applications has not shown greater variation (47.16 Moz), as the image quality is essential for diagnosis in various fields, such as medicine. All the silver used in photographic applications is discarded completely (solid or in effluent). At the present, several countries have been involved in silver recovering from industrial wastes due to the economic value and environmental impact they represent. The main source of silver recovery is the wastes generated by the photographic sector. Various technologies have attempted to recover silver contained in these wastes. However, they have not fully satisfied the requirements of maximum recovery, nor environmental level (less than 5 ppm) of silver in effluents [1,2]."

Jan 1, 2014

By M. Olper, M. Maccagni, C. J. N. Buisman, C. E. Schultz

The key point of the CX-EWS process is the conversion of lead compounds, contained in the active mass of spent batteries, into lead sulphide. The obtained lead sulphide is leached with ferric fluoborate electrolyte to dissolve lead and oxidize the sulphur from sulphide to the elemental form. The lead-rich solution is fed into a diaphragm electrolytic cell depositing lead and regenerating ferric fluoborate. The introduction of sulphate reducing bacteria technology in the sulphidization step of the battery paste improves dramatically the economics of the CXEWS process, reducing the costs of chemicals, avoiding gypsum disposal and minimising the unit operations of the process. This paper describes in detail this technology change with reference to the economics of the process.

Jan 1, 2000

By E. Morrice

Solubility of yttrium oxide (Y203) in fluoride melts was experimentally measured in the temperature range of 998 to 1273 K and, YF3 composition in LiF.YF3 melts varying from 20 to 50 mole pct using a graphite crucible in an argon atmosphere. Solubility of oxide in the melt was found to increase with increasing temperature and YF3 composition in the melt. An expression for in XY2O3 as a function of temperature for several melts was deduced. The calculated activity coefficients of Y2O3 in the melts exhibited a negative deviation from Raoult's law.

Jan 1, 1989

By Kenneth G. Thomas

This paper reviews the alkaline and acid gold autoclaving experiences gained at Barrick Gold Corporation. Alkaline autoclaving was operational at Barrick Mercur, Utah, U.S.A., on carbonaceous/sulphide refractory ore for eight years commencing in 1988. Acid autoclaves have been operational at Barrick Goldstrike, Nevada, U.S.A., on sulphide refractory ore since 1990 and now process 17,500 stpd of ore through six large autoclaves. Information is presented on operating costs, materials of construction, reagent requirements and flow sheet developments that reduced capital and operating costs.

Jan 1, 2000

By G. S. Nus

Technology for treating man-made metal-containing raw materials in DC electric furnaces with polarization of the bottom phase (PDF furnaces) has been developed and proven on a semi-commercial scale. PDF furnaces permit processing of man-made raw materials, i.e. current and accumulated intermediate products with rather high contents of valuable metals (i.e. slags, sludge, residues, Waelz slag, etc.), as well as secondary raw materials and virtually any type of waste using an environmentally safe technique based on sublimation of volatile metals and transfer of non-volatile metals and sulfur into the bottom phase in the furnace. Processes developed on the basis of the use of PDF furnaces make it possible to take advantage on a full commercial scale of electrolysis of molten materials, including electrochemical reduction of metals, intensification of their settling into the bottom phase and sublimation of volatile components, as well as to significantly improve recoveries of nonferrous metals, resolve the problem of excessive accretion formation in slagging processes and substantially improve the environmental situation. The low-grade discard slag obtained can be utilized in the construction industry; in particular, slag can be added to the limestone feed for cement manufacture.

Jan 1, 2006

By Gary A. Campbell

This article is an analysis of world consumption of copper for the years 1976-1996. It is done to provide a comparison of what has happened over this time period with the trends of previous years in order to learn more about world copper consumption and to forecast world copper consumption trends into the new millennium. The analysis begins by documenting the geographic trends of consumption of copper for the years 1976-1996 by both region and key individual countries. Then, variables based on the intensity-of-use hypothesis and the intensity-of-use technique are selected and tested against the observed consumption behavior by using the correlation coefficient technique. The statistical results and their implications for the consumption of copper into the new millennium are discussed.

Jan 1, 1999

By Kaixi Jiang, Lei Zhang, Sanping Liu, Yufang Wang, Xiaoping Zou

"Molybdenite concentrates are usually treated by roasting, but low concentration SO2 pollution is a problem. Extraction of molybdenum and rhenium from molybdenite concentrates with a pressure oxidative leaching (POX) and solvent extraction (SX) process was studied. A series of POX-SX laboratory and pilot tests were carried out on the molybdenite concentrate. In the POX stage, more than 95% rhenium and 15-20% molybdenum were leached into solution. Solvent extraction recovered the rhenium and molybdenum from the POX solution. The extraction rates of Re and Mo were above 98%. The loaded organic reagent is stripped with ammonia. The stripping ratio of Mo is more than 98%. Compared to the roasting process, the total recovery of Mo increased from 93% to 97%, and Re from 60% to 90%. In the coming five years, POX-SX technology will be competitive in China.IntroductionMolybdenite is the main resource for the production of molybdenum, and about 99% of the total molybdenum was extracted from molybdenite. Rhenium is one of the important new materials in national defense, space flights, nuclear energy and electronics, because of its high melting point, high strength, plastic properties and significant creep resistance. There are no single rhenium ores in the world; rhenium mainly co-exists with molybdenum. Consequently, molybdenite is also the main resource for the extraction of rhenium."

Jan 1, 2012

By Alex Moyano

The Codelco-Chile is considering different processing options for the projected concentrate from the Alejandro Hales mine (former Mansa Mina mine with high arsenic and antimony content of 6% and 0.6%, respectively), that will produce complex blister copper with high impurities contents, higher than the present values produced at the converting process of the Codelco Norte smelter processing only Chuquicamata concentrates. In order to know both the anodic copper quality and the metallurgical implications when a complex blister copper is processed in the refining process of the CN smelter, the Codelco and IM2 ?task force? evaluated positively the refining process for the complex blister copper by addition of alkaline fluxes at laboratory and industrial scale tests. The promising results of the tests done at laboratory scale at the Tohoku University facilities, allowed a large scale test planning to validate the lab-scale results in 3 refining furnaces of 250 t capacity at the CN smelter. The obtained results demonstrate the industrial technical feasibility to process a complex blister copper in the refining furnaces producing an anodic copper quality suitable for the electrolytic process.

Jan 1, 2006

By Christine P. Viecelli

As Phelps Dodge Corporation addresses the environmental challenges of the 1990's, water management has become a key element in an overall waste minimization strategy. The Phelps Dodge Hidalgo copper smelter has implemented a comprehensive water management program that includes management of both fresh and process water utilized by its pyrometallurgical operation. Two major technological strategies are being implemented. They are the design, construction and operation of a raw water pre-treatment facility to allow increased evaporation within cooling towers thereby minimizing blow down, and the use of a brine concentrator to treat and recycle significant quantities of process water. The end result of this program is a significant reduction in raw water pumped from the underlying aquifer into the facility as well as a decrease in process water which must be impounded or otherwise treated.

Jan 1, 1992