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By B. M. Fisher

A process for making electrolytic copper of high quality from copper flotation concentrates is described. The concentrates are first slurried and then subjected to a high-temperature, high-pressure, oxidation-leaching operation under controlled conditions. The resulting slurry from the oxidation-leaching operation is cooled or flashed to atmospheric pressure and then subjected to a solids-liquid separation. The separated liquor, containing the recovered copper values, is cooled and then fed to an electrolytic deposition operation where metallic copper cathodes of high purity are produced. The spent electrolyte is then subjected to a sulfide treatment to precipitate the residual amounts of copper not deposited in the electrolytic cells. The precipitated copper sulfide is recovered and recycled in the form of a slurry to the initial stages of the process.

Jan 1, 1976

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 Claude Lorenson

"The Spyrometer™ imaging pyrometer brings new dimension of imaging capabilities to temperature measurement technology by combining a high temperature video camera with scanning optical pyrometry. This gives the operators the ability to observe process conditions while measuring the temperature of virtually any object or region in the field of view. Since the lens tube of the camera can be air or water cooled, it is possible to see inside furnaces giving a very good view of many different types of metallurgical processes. Specific benefits in process knowledge and maintenance tasks for furnaces in different types of metal industries are discussed.1-Principles of Imaging PyrometryLens tube, camera and processorImaging pyrometry is the combination of video imaging and computer-driven pyrometry that measures the temperature of certain zones (selected by the operator) within the image viewed on the monitor screen. To obtain a detailed image of the metallurgical process under observance, it is necessary to place the optical objective of the camera close to the process. The Spyrometer™ (which is Quadtek's tradename for its imaging pyrometer) objective is housed in a lens tube that is cooled and permits insertion inside the vessel of interest. The length of the lens tube is chosen on the basis of making sure that the tip of the tube is just beyond the refractories lining the inside of the furnace. In most pyrometallurgical processes, we have found that the most reliable system set-up uses a water cooled shroud to cool the lens tube optics. A sapphire window provides maximum protection from the environment. Even in the case of the water cooled version, there is an air purge for the lens that keeps the objective clean and protects against hot metal splashes."

Jan 1, 1997

By Luben Savov

This paper presents recent research works on the removal of the tramp elements Cu, Sn, Zn and Pb from steel. The evaporation of Cu and Sn in iron-based melts treated at reduced pressure of the gas phase was studied in a vacuum induction melting furnace. The effect of chamber pressure, temperature and melt composition was investigated. Since the main source of contamination of steel with Sn and Zn is the recycling of tinplate and zinc coated steel, respectively, possibilities for the removal of meta1ic coatings in a scrap pre-treatment stage were studied, too. Tin was removed in the temperature range 400-5S0°C by treatment with reactive gases featuring high sulphur potential. Zinc can be removed by evaporation or by a combination of thermal and mechanical treatment. The paper discusses the thermodynamics of Pb in carbon-saturated iron melts, too.

Jan 1, 2001

By Osamu Takeda

A decomposition process for PCBs by using basic molten salts as a reaction field was investigated in order to establish a safe, simple and highly efficient decomposition process for polychlorobiphenyls (PCBs). PCB containing chlorine (e.g. 2, 2?, 4, 4?-tetrachlorobiphenyl) dissolved in n-nonane solution was supplied into basic molten salts (NaOH-Na2CO3 or KOH-K2CO3) maintained at 500-700 ?C together with the carrier gas (N2-21% O2) through an injection tube. The injected PCBs in a bubble are decomposed by the reaction with the molten salts and oxygen during rise in the molten salts. The decomposition efficiency of PCBs increased with increasing temperature and was achieved to be higher than 99.995% in a certain condition. From a series of systematic study, the effectiveness of the decomposition process for PCBs by using molten salts was demonstrated.

Jan 1, 2008

By Xue Sun, Dengfu Chen, Yuting Chen, Mujun Long, Song Xu, Helin Fan

In order to seek an effective extraction process for vanadium, the recovery of vanadium from a high Ca/V ratio vanadium slag was studied by sodium roasting and ammonia leaching. In the present paper, the oxidation and leaching process of vanadium slag was investigated by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS) techniques. The effects of ammonium carbonate concentration, leaching temperature and leaching time on the leaching ratio of vanadium were discussed. As indicated in the experimental result, the optimal (NH4)2CO3 concentration was 120g/L, leaching temperature was 60°C and leaching time was 20 min. Approximately 92% of the vanadium was recovered under the optimal conditions. Furthermore, by means of X-ray diffraction analysis, the phase transformations of the vanadium slag during roasting and leaching processes were analyzed and discussed.

Jan 1, 2014

By Wolfgang Baum

Case studies from epithermal gold-silver deposits in the western United States and in Latin America show that the routine use of process-related mineralogical studies has become an important tool for the reduction of development, capital and operating costs. Bypassing the mineralogical characteristics of epithermal gold-silver ores, as a result of fast-track development approaches, has resulted in multimillion dollar metal losses and/or in considerable modification costs of existing operations.

Jan 1, 1988

By Javier Antoñanzas, Juan Carlos Múgica, Lourdes Yurramendi

The gasification of wastes containing an organic fraction is usually performed at low-medium temperature using different kind of catalysts. The off gas obtained is a mixture of carbon oxides, mainly carbon monoxide, and hydrogen and can be used for different energetic applications. The main problem is the production of tars in the off gas that has to be separated from the valuable gas flow and, finally, treated separately. An interesting alternative is the partial or total treatment of organics at high temperature. In this case, the off gas contains a higher content of hydrogen and elemental carbon as particulate matter. The energetic source to obtain a temperature in the range of 1,000 - 1,200 ºC is obtained by a plasma torch. In order to make de process attractive, an important issue to be considered is to commercialize the carbon obtained for different industrial applications.

Jan 1, 2008

By Kunibert Hanusch

Copper in recycling material is accompanied by various groups of metals: 1) Metals which are much more negative than copper, such as Fe, Al, Si, P, Be They are mainly removed by fire refining during the recovery of copper and leave the process in form of slag. 2) Metals which are more positive than copper or difficult to separate by fire refining and which are partly reduced together with the copper. These metals are for example As,. Sb, Ni, Ag, Pb, Zn, Sn. They are enriched in intermediate products and recovered from these or remain for their major part in the fire-refined copper and can be separated by electrolytic refining and recovered from the electrolyte or anode slime. This report describes the process of Hüttenwerke Kayser AG in Germany and illustrates how considerable returns of material are partly required to separate or recover associated metals. They are finally removed in saleable products.

Jan 1, 1995

By Halvor Dalaker, Alain Marc Ferber, Thor Anders Aarhaug, Pål Tetlie

Off-gas monitoring of experimental reactors give little information about intermediate reaction products and reflect chemical equilibria at reduced gas temperatures. A reactor design with optical access was designed and tested in order to be able to qualify and quantify gaseous species from their emission spectra. By use of a sequence of sapphire, UV fused silica and IR transparent sapphire and CaF2 windows and lenses optical access to a hot, maximum 1800 °C, reaction zone was gained. A cooled area behind the reaction zone was used as a background in order to avoid signal saturation from reactor walls. In addition to molecular emission spectra, atomic emission lines are used to characterize stable gas constituents and radicals. The setup has been designed for the study of methane dehydrogenation experiments in order to investigate the carbon activity of reduction of oxide with methane, but has also been used to monitor gaseous silicon suboxide.

Jan 1, 2015

By Alicia E. Ares, Carlos E. Schvezov

In the present work it was observed the nucleation and growth of grains in the equiaxed zone of metal matrix composites (MMCs) samples directionally solidified wit the presence of columnarto- equiaxed transition (CET) in the samples. In order to do so, first, it was defined the difference between the real temperature at a given instant, which it is used in the analysis, its variation and furthermore, the variation in the solid fraction with time between the beginning and the end of solidification. It was determined a growth law assuming a lineal variation of equiaxed grain radius as a function of time, and also, it was expressed a law of grain density as a function of time, considering the presence of SiC and Al2O3 particles in the matrix. Finally, the results obtained were validated with measured values of grain density at each position of the thermocouples in the equiaxed zone of the solidified samples.

Jan 1, 2015

By Dong Hoon Han

The simultaneous sulfation by sulhr dioxide and oxygen of CaO and MgO in calcined CMA (calcium magnesium acetate) were investigated. he experiments were carried out in the temperature range from 700 to 830 "C and at the SO2 concentrations of 0.3 to 1 mol %. The oxygen concentration was kept at 5 %. Each sample was calcined completely before the temperature was lowered to the sulfation temperature. According to the ranges of partial pressure of sulhr dioxide and temperature, there exist three regions for the sulfation reaction: region I in which neither oxide is sulfated, region I1 in which only CaO is sulfated, and region 111 in which both oxides are sulfated. It was shown that the MgO in calcined CMA is sulfated at a rate comparable to that of CaO by forming a mixed sulfate phase. Thus, unlike MgO contained in other desulhrization materials, the MgO content in calcined CMA can be fully utilized for flue gas desulhrization.

Jan 1, 1999

By Jr. Brown, A. Calderara, A. L. Antozzi

"The result of extensive research into fundamental mixed metal oxide catalyst morphology has produced a next generation all titanium Dimensionally Stable Anode (DSA ®). This new DSA ® anode, patent pending, is tailored for electrowinning of non-ferrous metals (copper, nickel, cobalt, zinc) by means of this new coating technology.These DSA ® anodes are characterized by a hanger bar with vertical distributor bars, having primary titanium mesh attached by weldments. The active mesh is provided with noble-metal electrocatalytic coatings, consisting of iridium and/or ruthenium oxides, obtained by thermal decomposition of precursor solutions applied to the titanium substrates. The catalytic activity of state-of-the-art DSA ® anodes is increased by controlling the crystallite size of the noble-metals without decreasing the decomposition temperature. It is known that below a certain value (typically 400°C) the stability of these oxides, and associated lifetime, is seriously compromised. A highly active DSA ® anode, consisting of a quasi-amorphous phase, is obtained at high temperature (above 450°C), therefore not compromising lifetime performance. Through optimization of these design parameters, the manufacture of these novel anodes was identified.DSA ® anode performance advantages include: lead-free ' green' all titanium anodes, true leadfree cathode quality, energy savings of 0.3 to 0.55 V can be realized depending on the EW application when compared to industry standard lead-alloy anodes, eliminate need for cobalt sulphate addition required for lead anodes, sustainability designed into long-life recoatable anode structures, increase plant cathode output through increased current density operations, improve plant on-stream production, no sludge generated or removed, and improve current distribution producing smooth high efficiency cathode.Introduction of ProductThere are many factors to consider when engineering a high performance DSA ® electrowinning anode. Half of the anode's performance is derived from the physical attributes of the electrocatalyst and methods employed when applying this catalyst to the titanium anode structure. The other half of the performance benefits relate to the proper structural design of the anode. In this paper, we will highlight the anode development program in which De Nora has invested to provide the Electrowinning marketplace with a high performance anode product."

Jan 1, 2012

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Mario H. Castro-Cedeno

"A design for a handheld MEMS chemical detector is proposed. The detector will be used to detect trace amounts of chemicals in air. It can detect drugs, toxic chemicals and/or explosives. The proposed detector will use ion mobility spectrometry (IMS), a technique that is well known for accuracy and has been used in the past in suitcase sized chemical detectors. The separation and detection of the chemicals occurs in the drift channel and the process was modeled using the finite element method and CoventorWare modeling software. A manufacturing process sequence for the drift channel is proposed and was demonstrated.IntroductionThe goal of this effort is to design, mode~ and prototype a MEMS chip that will be the key component in an ion mobility spectrometer (IMS). This technique uses and asymmetric potential to separate the various ion species in a stream of incoming air [1-4]. One advantage of IMS is its ability to separate chemical species from air at atmospheric pressure and temperature. This is a requirement for a simple to use handheld drug or chemical detector. IMS can be used to detect drugs, toxic chemicals and explosives and it is well known for accuracy in detecting very small amounts of chemicals. This chemical detection technique has been used in the past, but not in handheld detectors.One variant of IMS is the high-field asymmetric waveform ion mobility spectrometry or FAIMS [3]. The FAIMS process, shown in Figure l, works as follows: a gas sample is admitted into the instrument where gas molecules are ionized, typically by a weak radioactive isotope source, ultraviolet light source; and more recently through field emission. The ions move along the length of a channel while they are separated in the transverse direction by an asymmetric electrical potential. The potential, in the form of an asymmetric waveform, causes relative motion between the various chemical species. The species that hit the charged top and bottom plates are neutralized and only those ions that move along the center are detectable as charged chemical ions at the end of the channel."

Jan 1, 2004

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

By Banqiu Wu, Ramana G. Reddy, Robin D. Rogers

Experimental studies on aluminum recycling via electrolysis in ionic liquids were carried out at the temperature of 105°C. Impure aluminum was dissolved at the anode and pure aluminum was deposited on a copper cathode. The products were characterized using an optical microscope, micro-image analyzer, X-ray diffraction, emission spectrometer, and atomic absorption analyzer. The electrorefining process with a current density of 310 - 730 AJm2, and current efficiency of about 99% was obtained. Impurities such as Si, Cu, Zn, Fe, Mg, Cr, Ni, Mn and Pb were removed as anode residue. Impure aluminum was purified from 79.8wt% to 99.9wt%. At a cell voltage of 1 volt, the energy consumption of about 3 kWh/kg-Al was obtained. The process has advantages of low energy consumption and low pollutant emissions, compared with the current industrial refining process.

Jan 1, 2000

By Dengfu Chen, Huabiao Chen, Yunwei Huang, Mujun Long, Youguang Ma, Lintao Gui

In the current work, a three-dimensional model coupling turbulent flow, heat and solute transport was developed to investigate the solute transport and redistribution in the mold of slab continuous casting where the Reynolds number is very high and the molten steel flows strongly. The conservation equations of momentum, energy and species for a multicomponent system which includes solute element C, Si, Mn, P, S were solved with the commercial software ANSYS Fluent. The parameters used in the model are based on the actual continuous casting. The fluid flow, temperature distribution and solute elements distribution were analyzed. Results showed that negative segregation occurred near the strand surface, and the species concentration reached a peak value at the solidification front during solidification. The segregation degree of solute element S is higher than the other solute elements because of its lower equilibrium partition coefficient. The species concentration in the liquid pool is homogeneous because of the turbulent flow effect.

Jan 1, 2015

By K. Watling

Vibrational spectra of surface and solution compounds formed during cyclic voltammetry of a gold electrode in a deoxygenated 0.01 mol dm-3 NaCN solution have been examined using surface-enhanced Raman scattering (SERS) spectroscopy. The presence of cyanide at the electrode surface was indicated by Raman bands characteristic of the carbon-nitrogen stretch, CN.. Chemisorption of cyanide on the gold surface was evidenced by the presence of vibrational modes due to gold-carbon stretching, AuC, and gold-carbon-nitrogen bending, AuCN. Prior to the disappearance of the surface cyanide stretch band, a limiting value of the CN was obtained, the same as the value reported for adsorbed cyanide. Effects upon the voltammetry and vibrational modes of surface species due to additions of silver and lead to the gold-cyanide system have been observed.

Jan 1, 2003

By A. Haxhiaj, E. Haxhiaj

"The paper has as a studying object the issue of effective management of gasses’ heating and dusts in reductive melting process in lead (Pb) metallurgy. It also analyses the issue related to the usage and recycling of dusts and gasses in all pyro-metallurgical processes of technical lead production. The paper contains the analysis of technological process of separation of humidity, gasses, and dusts of valuable remainders in “Trepça” plant. Paper has the results of theoreticalexperimental studying, analytical and graphical of gasses thermal balance depending on height and composition of load, and the coke quantity on load for reductive melt in “Water-Jacket” furnaces. With thermal balance, having into consideration all parameters of heat in entry and exit depending on aforementioned factors we aimed to optimize the parameters of the process, keeping the attention to the minimization of energy consumption, and the overall influence on environment.1. IntroductionThe upper part of the furnace which is the study point of this paper lies from the reactions zone of Water-Jacket furnace and it also includes the furnace neck. In this zone has been elaborated the zonal material balance referenced third in the row. The separation of humidity, dusts, gases and lead with gases depends on many parameters like temperature, load composition, and height of load inserted in the furnace, and also the height of preheating zone in Water-jacket furnace. Lead oxidizes in reaction zone of the furnace and exhales with gases like dusts and small particles after which falls in worthy storage of Trepça plant and has negative effects in environment, and economic stability of reductive melting process of Water-jacket furnace. Thermal balance of gases in this zone depends on many factors; height and load composition, coke quantity in a load. The calculation has been done as the standard methodology of thermal calculation is done; moreover, by using a computer for mathematical models which enables very accurate results. We must emphasize that acquired and used heat in reaction zone and melted materials is calculated in others studies, so their influence in preheating zone is assumed."

Jan 1, 2010