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By R. Y. Wan

Thiocyanate was evaluated for gold recovery from low-grade refractory gold ores following biooxidation for an acidic heap leaching approach. One of the important features in using thiocyanate is that the leaching can be performed in acidic media, thus avoiding problems related to neutralization and material handling as leaching with alkaline cyanide. Also, the acidic leaching enables the use of ferric ion or bioleach solution as oxidants. In this study, Newmont-Nevada low-grade refractory sulfidic ore was biooxidized in columns at a particle size of 100% passing 102 mm. Thiocyanate leach on the biooxidized ore sample was performed on both ground samples in pulps and coarse material in columns using ferric ion as an oxidant. The variables of thiocyanate and ferric ion concentrations were compared for effect on leaching. Thiocyanate leach results are encouraging and indicate potential for development of a practical process. Gold extractions by thiocyanate are comparable to cyanide leach. Thiocyanate consumption was higher than cyanide, but was in an acceptable level.

Jan 1, 2003

By Jouko Kallionen

Advanced Flotation Technology is the application driven design of flotation cells to achieve the optimum performance for each type and grind of flotation. This can be applied to roughers, scavengers, cleaners and specialty cells such as those to float hydrocyclone underflows in both primary and regrind circuits in order to reduce overgrinding. Standard, engineered, components are matched to provide mechanism design and cell dimensions for each case according to feed parameters and flotation type. Advances in process control have been achieved with high level controls and operator information data. This has gained a higher degree of understanding of cell operation and ore type being processed. Excellent results of this Advanced Flotation Technology in large scale porphyric copper ore have been achieved and designs through 7000 cu ft (200 m3) are currently available for high capacity concentrators. This paper will detail how flotation cells are more responsive to the exact requirements of the duty specified.

Jan 1, 1999

By Dong Liu, Zejian Yang, Yong Li, Tao Jiang, Xiangxin Xue, He Yang

"The structure, composition, morphology, and adsorption property of UV-vis light of as-prepared samples were characterized using XRD, SEM, FTIR-EDS, and UV-vis DRS. UV-visible light induced photocatalytic degradation of methylene blue ~) over Ti02-doped diopside was investigated. Experimental results show that doping Fe + induced the formation of Ti-0 or Ti-0-Si in diopside, and promoted the light adsorption property of diopside. Photocatalytic reactivity of Ti02-doped diopside obviously depended on content of doping Ti02. The diopside with 3% Ti02 exhibited the superior photocatalytic activity with 76% degradation of methylene blue under light irradiation for 3 h.IntroductionPhotocatalytic technology has been extensively studied in the process of dealing with inorganic and organic pollutants. Ti02, with its own non-toxic, stable, low-cost and other advantages, has become the most widely studied photocatalytic materials[l-SJ_ The low utilization quantum made it restricted in the practical application. SrTi03 as the representative of the perovskite[9·121, Bi2W06 for the composite oxide[13,141, also attracted wide interest in the photocatalytic studies. However, these photocatalytic material has been mostly prepared in relatively strict experimental conditions with chemical reagents, they had small production, high cost, which made them difficult for practical applications.In our country, there has 400 million tonnes of ti-bearing blast furnace slag (TBBFS) each year in the process of smelting pig iron, which has lead to waste of titanium resources and pollution of the surrounding environment. In recent years, studies have shown that TBBFS instead of pure Ti02 to be photocatalytic materials is feasible[ 151. TBBFS has not only been higher photocatalytic degradation activity for the o-nitrophenol, methyl orange, nitrobenzene and other organic matter[16-191,but also exhibited excellent in the process of dealing with inorganic heavy metals in waste water (containing Cr6+i201. If TBBFS can be successfully applied to photocatalytic technology, the will make large accumulation of titanium-bearing slag reasonable used, so as promote the re-use of energy. At present, our understanding of the photocatalytic activity of TBBFS is steadily deepening. Photocatalytic activity ofCaTi03 has been reported as one of the main minerals ofTBBFS [21'21J, However, there were few studies for Another major mineral of TBBFS - diopside which had the content of9-15%. diopside would doped with Ti02 In the process of smelting pig iron, therefore, Ti02-doped diopside's photocatalytic activity in the UV-Vis was mainly studied in this paper."

Jan 1, 2013

By Th. Probst, M. Reuter, H. Orbon, U. Boin, J. Vonken, P. Vonk

Although secondary aluminum industry is well established in the world, the recycling process still requires further development to adequately control the process for a higher aluminum yield and a better product quality. In the present paper, recyclabilities of different aluminum scraps have been experimentally studied. Four types of commercial scraps were characterized and melted at 800 - 900 °C to recover 'aluminum metal with the protection salt flux of NaCl-KCl-Na3AlF6 under nitrogen atmosphere. According to the results, the difficulty of recycling aluminum scrap depends on the cleanness and the ratio of surface area to body volume. More non-metallic contaminates and higher ratio of surface area to body volume usually led to a lower metal yield. Usually cast ingots gave better results than rolling mill cuttings under similar conditions. Bottle caps can be recycled more easily than the margarine foil. The effect of temperature was not as significant as the composition of salt flux. The addition of cryolite was essential for a better metal recovery, especially for the scraps with higher surface area. Recycling

Jan 1, 2000

By James D. Navratil

The mineral magnetite, or synthetically prepared iron ferrite (FeO?Fe2O3), has been used to separate a wide variety of substances, such as dissolved metal species and particulate matter, from wastewater. In the absence of an external magnetic field, activated magnetite readily adsorbs numerous metal species including actinide elements. In the presence of the external magnetic field, enhanced capacity was observed in using supported magnetite for removal of actinides and heavy metals from wastewater. The enhanced capacity is primarily due to magnetic filtration of colloidal and submicron particles along with some complex and ion exchange sorption mechanisms. The removal of the magnetic field and use of a regenerating solution can easily regenerate the loaded magnetite. The process has recently been tested for the removal of other metal ions including cobalt and iron. This paper will review previous work on the use of iron oxides for wastewater treatment and discuss the development and potential of the magnetic filtration/sorption process for wastewater treatment applications in hydrometallurgy.

Jan 1, 2003

By Joachim Lemke

The stainless steel sheets of permanent cathodes at Norddeutsche Affinerie (NA) were damaged by corrosion after nearly 11 years in operation. The necessary raising of the strength for stripping the copper had increased the deformation of the stainless steel blades. Current efficiency declined. After investigating the possibilities, like buying new cathodes or treating the steel surface, i.e. by sliding, a repair process was developed whereby the stainless steel sheet was exchanged. Special laser technology for cutting used blades und welding new stainless steel sheets underneath the used hanger bar was applied because the energy input into steel is the lowest of all welding methods. The new stainless steel sheet was welded with the rolling line in a horizontal direction. The achieved flatness of the repaired cathode blades amounted to less than 4mm per meter. During 11 months NA repaired nearly 36,000 permanent cathodes and put them back into operation. Repair costs were much lower than the costs of buying new ones and current efficiency increased again to more than 96% with a current density of 340 A/m².

Jan 1, 2006

By Brady Butler

Many high capacity metal hydrides exhibit a high degree of stability in the hydrogenated state. This stability leads to a number of significant design problems with regard to the low temperature kinetics and thermodynamics of dehydrogenation. Nanometric metal hydride materials provide a promising route for increasing the reaction kinetics while altering the thermodynamic stability of the material. The use of nanometric metal hydride materials for hydrogen storage has largely been absent because of the difficulties associated with the synthesis of these materials. In this paper, research results on the synthesis of lithium based metal hydrides by vapor phase reactions are presented. The lithium based compounds that have been made in our lab include nanosized powders of metallic Li, Li₃N, LiNH₂ and LiH. The vapor phase process has also been used to custom engineer Li-based materials with other alloying elements or doping elements. The dependence of the characteristics of these materials on synthesis process parameters is studied. The effects of nanoscaled particle sizes on the kinetics of dehydrogenation and hydrogenation reactions are also explored.

Jan 1, 2006

By V. Gel

An analysis of the operation of rotary tilting furnaces has indicated that they ensure better recoveries of metal when smelting lump scrap from aluminum slags, brass and bronze. On the other hand, processing of slags (concentrates obtained by mechanical upgrading) in pear-shaped furnaces results in much lower performance values as might be expected. At the Novgorod metallurgical plant a process for blister copper production in a rotary TROF converter (Outokumpu, Finland) has been introduced on a commercial basis. Smelting of brass and bronze scrap to produce blister copper is carried out using the technology developed in Russia and differing from the Outokumpu technology by the types of flux used and the blowing conditions in fuel burners and for melt oxidation, as well as by the design of gas removal system, the design of nozzles for melt blowing and the use of carbonaceous reductant (coal) for magnetite reduction in slags. Industrial-scale testing has demonstrated that by means of special techniques the 30-tonne converter productivity can be increased by 30% to 40% as compared with its rated productivity.

Jan 1, 2006

By Scott Shuey

The processing of post-consumer materials is an area being addressed by many industries and multiple engineering disciplines. While metal scrap and high-value uniform waste streams tend to find their way back to their respective parent processes, the more complex and low-cost ubiquitous materials, such as Polyvinalchloride (PVC) and Polytetrafluorethane (PTFE), tend to show up in many processing streams. From a metallurgical perspective, pyrometallurgical processing of a mixed metal/organic/oxide waste material allows for the recovery of thermal energy in conjunction with the recovery of metal values. The evolution of halogenic acids during elevated temperature processing can create complications with both the materials of construction of the processing equipment as well as gas stream processing. The need for dust collection coupled with a high acid content, necessitation high-volume scrubbing, increases the costs associated with gas handling. Control of the halides through entrapment as a solid in-situ during processing would simplify downstream processing. Alkali-halide complexes are being evaluated by researchers at CSM for mixed metal/polymer waste material treatment, recovering halogens as salt complexes.

Jan 1, 2006

By Graeme Miller

The geotechnical characteristics of the ore are important in understanding the kinetics of a copper heap leach. These characteristics can indicate potential problems and can be used to determine the semi-quantitative changes in field kinetics as compared with column kinetics. The application of this approach allows a more rigorously based determination of ?scale up factors? than has been the case the date. The shrinking core model has been shown to be a poor predictor of leach kinetics based on the crushed ore size distribution. However the model itself is a very useful tool to analyse commercial heap data. Significant geotechnical parameters such as: bulk density / stress characteristic, limit moisture capacity and particle density are used to determine the effect of changes on the diffusion controlled leach rate. By consideration of the geotechnical reaction of the ore mass the leach rate changes are related to changes in these variables. Analysis of commercial heap data has indicated effective diffusion lengths of up to ten times the largest particle size.

Jan 1, 2003

By B. J. Beaudry

The effect of various levels of purity of the rare earth fluorides and the calcium reductant used to prepare rare earth metals were determined. Metals which have low melting points such as La, Ce, Pr and Nd are not purified by distillation or sublimation. Impurities in the reactants remain as contaminants in these metals. Gd, Tb, Y and Lu which have slightly higher vapor pressures at their melting points than the first four metals are usually distilled to remove the Ta or W impurity introduced by the crucible and are purified slightly with respect to 0 and N by distillation. Rare earth metals that have high vapor pressures such as Sc, Dy, Ho and Er can be purified with respect to 0, N, C, as well as Ta or W by sublimation. The most volatile rare earth metals Sm, Eu, Tm and Yb are readily purified by sublimation and are usually prepared by a reduction-distillation process directly from the oxide. The importance of each step of the processes in determining the final purity of the individual rare earth metals is discussed.

Jan 1, 1989

By Li Cheng

The SKS copper smelting process was jointly developed by Shuikoushan Mining Corp. and ENFI (Beijing Central Engineering and Research Institute for Non-ferrous Metallurgical Industries) in China. It is a new bath copper concentrate smelting process with oxygen enriched air. The pilot plant testwork was completed successfully in 1993. SKS has demonstrated to be an advanced bottom blown smelting process. This technology got the First Class Prize of Scientific and Technological Progress awarded by CNNC (China National Non-ferrous Metal Industry Corp.) in 1994. The SKS process has significant capital and operating cost advantages. Its environmental and industrial safety and hygiene performance represents a substantial improvement when compared to conventional technologies. The technology has generated great interest in the Chinese metallurgical industry. Feasibility studies and basic designs have been carried out to incorporate in retrofit and green field smelter projects in China and abroad. This paper describes the history of the pilot plant operating data (50 tonnes dry feed/day), and discusses the features of the SKS technology, its application and possible future trends.

Jan 1, 1999

By Joel F. Flurnerfelt

Molten Al and Al alloys containing si, Mn, Ti, and y have been lanced with nitrogen-bearing gases. These lancing experiments provided the means for observing what phases form during exposure to nitrogen-bearing gases for finite periods of time, <2 minutes, at high temperatures, >1290oC. The experiments were conducted in sn induction heated drop tube furnace apparatus. The overall premise of these experiments was to select those Al alloys and gas compositions that show promise of forming secondary dispersoid phases, particularly AIN, in the Al matrix. The alloys selected will be atomized using gas atomization reaction synthesis (GARS) using the most favorable conditions. In this case, the chosen Al alloy will be atomized with a nitrogen-bearing gas, such that the Al and gaseous nitrogen species react to form a dispersoid phase within each powder particle. The powder particles that result from this "aggressive" GARS-process would be essentially Al metal-matrix composites within a uniform distribution of dispersoids. To date, only high-purity Al has been atomized using a mild GARS reaction. This work is funded by the Materials Science Division of DOE-BES under contract number W-7405-Eng-82.

Jan 1, 1996

By F. L. Meng, C. S. Henkel, R. M. Alchalabi

For secondary aluminum producers to maintain a profitable melting operation, five technical factors have to be taken into account from the initial furnace building decision to the final operation and production. These factors are furnace design, furnace equipment selection, furnace control, furnace charge selection and inventory, and furnace operation. Any of these five factors, if not chosen or performed wisely, will likely result in sub-optimal melting operation. As a result the MeltSim melting optimization package has been developed by the collaborative effort of Chinook Sciences and AMCS Corporation to take into account these five factors. The package is a mixture of hardware, software, science and experience. The package incorporates years of reverb furnace operational observations, start-up installations, furnace operator experience and furnace physiochemical mathematical model development. The optimization package enables aluminum producers to design new furnaces, select and place proper equipment, optimize existing furnace operations, and convert air-fuel installations to oxy-fuel. The package provides furnace operation monitoring and advisory signals, and furnace automatic optimal control to furnace operators, shift supervisors and plant managers, all customized, based on plant and melter need and ease of information management.

Jan 1, 2000

By Florian Kongoli

The overall productivity and efficiency of sulfide smelting plants depends considerably on the productivity and efficiency of each unit furnace operations. Furthermore, the efficiency and productivity of each furnace affects and dictates to a certain degree the process of managing the flow of materials from one unit to another. A furnace with low productivity, several technical problems or high frequency of accidental shut downs can easily become a temporary or a permanent bottle neck in the entire flowsheet and can be the cause for a low productivity and efficiency of the entire plant. As a result, controlling, optimizing and automating the individual furnace operations in order to assure a stable process but at the same time to increase productivity is an indispensable need. In this paper, the authors discuss their recent work in effectively controlling acute industrial furnace problems such as magnetite build-up and accretions, eliminating unnecessary slag foaming, decreasing slag losses etc. as well as the intensification, optimization and automation of a series of furnaces in sulfide smelting through a unique physical process modeling that correctly simulate the industrial furnace operations and avoid guessing and uncertainties. The advantages of this new approach have been discussed.

Jan 1, 2006

By Wen-Ming Chien

Low temperature X-ray diffraction and thermal property studies of the solid-solid state phase transition for the polyalcohols (pentaerythritol (PE), pentaglycerine (PG) and neopentylglycol (NPG)) thermal energy storage solid solutions have been investigated by using X-ray diffractometry and differential scanning calorimetry (DSC) methods. X-ray diffraction studies on polyalcohols solid solutions, PE-NPG and PG-NPG, are from ?10oC to 50oC. XRD results shows the + mixed phase at the related low temperature (?10oC) for both PE-NPG and PG-NPG solid solutions. At high temperature range, XRD results show phase for PG-NPG solid solution and + mixed phase for PE-NPG solid solution. There are only two Bragg peaks, (111) and (200), shown in phase XRD patterns. The polyalcohols solid solutions have been cycled 5 times between -20oC to 100oC at different DSC scan rates to study the phase transition properties. DSC results of both PE-NPG and PG-NPG solid solutions show that the solid-solid state phase transition is near room temperature. Details of low temperature phase transition XRD and DSC results of PE-NPG and PG-NPG solid solutions will be presented

Jan 1, 2006

By Kimio Itagaki

As a fundamental study for smelting the copper matte with high contents of arsenic and antimony in a strongly reducing condition, phase relations between the liquid matte and copper-rich alloy phases in the Cu-Fe-S-As or -Sb quaternary system and between the liquid matte and iron-rich alloy phases in the Cu-Fe-S-As or -Sb system saturated with carbon were determined at 1473 K by a quenching method. Activities of arsenic and antimony in these systems were also measured at 1473K by Knudsen cell-mass spectrometry. Furthermore, distribution ratios of silver, gold and platinum between the liquid matte and copper-rich or iron-rich alloy phases were determined in relation to the arsenic or antimony content in the systems. On the basis of these data, the elimination of arsenic and antimony from the matte to the iron-rich alloy (speiss) and the recovery of precious metals in reduction smelting of the copper matte were evaluated. It was suggested that the addition of pig iron to make a strongly reducing condition and form the iron-rich alloy, which is fluid at smelting temperatures, will be useful for fixing arsenic in the speiss.

Jan 1, 2006

By Shinya Hodoshima

A catalysis pair of tetralin dehydrogenation / naphthalene hydrogenation has been proposed in the present paper as a liquid organic hydride for operating stationary fuel cells. Catalytic naphthalene hydrogenation, having been commercialized since the 1940s, proceeds to generate decalin via tetralin as an intermediate. The storage capacities of tetralin (3.0 wt%, 28.2 kg-H2 / m3) are lower than decalin (7.3 wt%, 64.8 kg-H2 / m3) but both tetralin dehydrogenation and naphthalene hydrogenation are much faster than the decalin / naphthalene pair. Moreover, existing infrastructures such as gas stations, chemical tankers and tank lorries are available for storage, transportation and supply of hydrogen. With respect to the stationary fuel cells with large space for hydrogen storage, tetralin as a hydrogen carrier is superior to decalin in terms of fast hydrogen supply or power density. Rapid hydrogen supply from tetralin under mild conditions was only accomplished with the carbon-supported metal catalysts in the ?superheated liquid-film states? under reactive distillation conditions. In contrast to the ordinary suspended states, the catalyst layers superheated in the liquid-film state gave high catalytic performances at around 250OC. As a consequence, both serious coke formation over the catalyst surface and excessive consumption of exergy were prevented simultaneously.

Jan 1, 2006

By S. H. Castro

In 1997 Chile was the world&apos;s largest copper mine producer with around 3.4 million metric tomes of copper. Conventional technology (conminution-flotation- smelting-converting-electrorefining) for copper sulfide ores was used. For copper oxidized ores hydrometallurgical processes (heap leaching-solvent extraction- electrowinning) were employed. Consequently, the most important waste effluents include flotation tailings, gaseous emissions, smelter slags, acidic and alkaline wastewater, electrolytic sludges, solid residues from leaching, etc. The introduction of stricter environmental regulations are forcing the Chilean industry to minimise the generation of waste and promote cleaner production. Gas emissions such as SO2 and arsenic from smelters and process wastewater are the major problems at this stage. The environmental impact assessment of gas emissions in all six largest smelters namely Chuquicamata, Caletones, Potrenllos, Ventanas, Paipote and Chagres led to design a "decontamination plan." The implementation of this plan resulted in (i) the installation of sulfuric acid plants for SO2 abatement and (ii) the installation of electrostatic precipitators to remove arsenic oxides condensed from cooling gases. The aim of this paper is (i) to describe the type of waste associated to the various stages of the metallurgical processes and (ii) review the main abatement technologies used in medium and large size companies.

Jan 1, 1999

By S. de Vries, B. Wasmund, J. Metric, N. Voerrnann, S. Kasinger

Gulf Chemical & Metallurgical Corporation (GCMC) operates a circular DC electric smelting furnace to treat nickel and cobalt bearing residues at its plant in Freeport, Texas. The furnace, originally built by others, has experienced problems including runouts through the hearth and the lower sidewall. Hatch has designed several improvements to the furnace to alleviate these problems. The single anode at the centre of the hearth was replaced with a patented system of twelve air-cooled copper anodes evenly spaced around the furnace lower sidewall. The DC power supply comprises two transformers and two rectifiers operating in parallel. The water-cooling system on the bottom and lower sidewall shell plates was replaced with an air-cooling system using copper cooling fins. The existing row of water-cooled copper coolers in the metal bath zone was re-designed for greater heat removal capacity and better element joint sealing, and a new row of water-cooled copper coolers was added to cool both the alumina bath and freeboard zones. The existing water-cooled metal and alumina tapblocks were also re-designed for more robust cooling. A binding system was added to provide refractory compression that reduces the risk of liquid leaks. Finally, the furnace tilting frame was relocated to the top of the furnace where it is less likely to be damaged.

Jan 1, 2000