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By Roger Altman

The solubility of copper in primary spinel crystals encountered in reverberatory slag samples has been determined by electron microprobe analysis. These spinels, which ranged in composition from 22% A12O3 to pure magnetite, contained small quantities of dissolved copper (0-0.4%). Based on literature data it was estimated that the solubility limit of copper in solid magnetite is no greater than about 1% at 1200°C and about 2% at 1250°C. However, it was found that practically every spinel crystal examined contained significant amounts of matte inclusions. Further examination of converter slag revealed large quantities of irregularly shaped precipitated magnetite crystals which contained a large proportion of copper inclusions. Additional experimentation showed that the total copper content in reverberatory slag samples was greater than the sum of the estimated en- trained plus dissolved matte in the slag. This difference is believed to be significant and is due to the presence of matte inclusions in the spinel crystals. In the present reverberatory slag samples these inclusions accounted for about 1/2 of the amount of sulfide directly entrained in the slag.

Jan 1, 1976

By Mingmei Zhu, Xin Qiu, Xiaofei Dou, Yu Wang, Tiancheng Lin, Bing Xie

In this study, the slag forming route of the single-slag steel melting when smelting medium phosphorus hot metal was investigated. The CaO-SiO2-FeO-MgO-MnO-P2O5 as hexahydric slag system was adopted in the converter. The effect of slag composition on liquidus was calculated by FactSage, the isogram of phosphorus distribution ratio was calculated by using the regular ion solution model, combining these two tasks, the theoretical slag forming route was obtained. Through experiments, the actual melting point ofthe corresponding components on theoretical slag forming route was obtained, in this way, the theoretical slag forming route was confirmed. Then, the theoretical slag forming route was applied to industrial test in a 210t BOF. After using the new slag formating route, the dephosphorization ratio was increased 3.6% while the auxiliary materials consumption was reduced, and the cost of steelmaking was reduced.

Jan 1, 2015

By R. G. Reddy

The effect of solid particles on viscosity behavior of Na2O-O-B2O3-SiO2 melts of composition XSio2/XNa2o =0.5 and in the temperature range of 900- 1150 K was studied. Samples were analyzed by X-ray diffraction and optical microscopy. The results showed that a crystalline phase (NaBO2) was formed and its amount increases with decrease in X,, from 0.50 to 0.25. The experimental viscosity values were compared with the predicted values using our viscosity model developed earlier. At low temperatures, for low content of B2O3 , the experimental values exhibits a large deviation from the predicted values. It was concluded that the deviation was due to the formation of solid particles in the molten slags. The existence of these solid particles increased the viscosity values significantly. A new viscosity model was developed to include the effect of solid particles.

Jan 1, 1993

By Alicia Esther Ares, Carlos Enrique Schvezov, Alejandra Silvina Roman, Claudia Marcela Méndez

In this paper the structure of aluminum based alloys and their corrosion behavior by using different electrochemical techniques as characterization methods are considered. Currently, it becomes imperative to know the role of the Al2Cu against the susceptibility to corrosion of these alloys. The present work aims to studying the electrochemical behavior of aluminum base alloys with the following compositions: Al-1wt.%Cu, Al-4.5wt.%Cu and Al-15wt.%Cu (with different grain structures), in 1M NaCl solutions, at room temperature. Cyclic potentiodynamic polarization tests were performed and were found that the alloys with more than 1wt.%Cu in the matrix have an unstable behavior and without tendency to reach passivity. The equivalent circuits derived from electrochemical impedance spectroscopy technique (EIS) generally showed two capacitive contributions. The susceptibility to corrosion becomes a complex function, not only of copper concentration and structure, but also with interdendritic spacings and distribution of phases in the alloys.

Jan 1, 2015

By Denise C. R. Espinosa

The amount of secondary batteries are increasing about 15% by year. Among these batteries, it can be highlighted the NiCd ones, due to their high consumption. In Brazil, the consumption of NiCd batteries grown quickly in the last 5 years, due to the dissemination of cellular telephones and other electronic devices. The first step of a process to recycle spent NiCd batteries is the pretreatment through unit operations of mining treatment. The aim of this work is to define a physical pretreatment to conditioning the waste to a pyrornetallurgical recycling process of spent NiCd batteries used in cellular telephones. Batteries were disassembled by hand to release the different components. The studied batteries are basically composed (by weight) of: 78% nucleus, 18% plastic case and 2% circuits. The grinding of the batteries was performed by knife mill and also by hammer mill. After grinding the material was screened and submitted to a magnetic separator.

Jan 1, 2001

By William Petruk

A mineralogical and image analysis study was conducted on samples of U tailings from pilot-plant runs on Midwest ore in Northern Saskatchewan. The tailings had been subjected to simulated weathering for the equivalent of 10 years in a tailings facility (lysimeter). The pH varied from 7.0 at the beginning of the test to 5.9 at the end. The results show that during the simulated weathering sane of the gersdorffite, uraninite, galena and pyrite had oxidized, with gersdorffite being the most reactive and pyrite the least. Reaction was evident at the top of the lysilleter , but was most intense at the seepage discharge. sane of the released ions precipitated as Ni, Pb, and U arsenates, sulfarsenates, sulfates and oxides on particles of all minerals. Green crystals of Ni sulfate and white crystals of ca sulfate had precipitated at the surface of the lysilleter. Clay minerals and chlorite had washed from the top of the lysirneter towards the seepage discharge.

Jan 1, 1989

By James Wang

In July 2003, The Office of Hydrogen, Fuel Cells and Infrastructure Technologies of the Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy solicited Grand Challenge Proposals to establish three Centers of Excellence in hydrogen storage developments for reversible metal hydrides, non-reversible chemical hydrides and carbon storage materials, respectively. The program mission is to research and develop cost-effective, on-board hydrogen storage systems that enable a minimum range of 300 miles within the weight and volume constraints of the vehicle. Currently, no hydrogen storage technology available can meet the DOE cost and performance targets. In April 2004, Sandia National Laboratories was selected by DOE to lead the Metal Hydride Center of Excellence with partners from 5 other national laboratories. We will present the organization and recent accomplishments of the Metal Hydride Center which is confident to accomplish DOE/FreedomCAR and Fuels Partnership objectives for 2010 in hydrogen storage for vehicular transportation applications.

Jan 1, 2006

By Tsisana Gagnidze

A processing of technogenous wastes, which involve a gold-containing sulphide minerals, is a potential source to supplement the gold reserves. Hence, searching of ecologically safe and economically reasonable methods for processing of gold-containing technogenous wastes is a topical problem. To increase a parameters of gold extraction and to simplify a technology of the processing of above-mentioned wastes of sulphide minerals, an investigations have been carried out in the direction of the use of the method of electrochemical leaching without any preliminary processing of the mineral. It was established experimentally that an introduction of nitrogen containing organic additive into chloride solution favours to reduce a Red/Ox potential of the solution from 0,8÷1,2 V to 0,35÷0,5V, which permits to conduct the process of direct electrochemical leaching at ?soft? oxidation regimes at temperatures 20-300C C without an environmental contamination by molecular chlorine and with a high degree of a gold extraction up to 80-90%.

Jan 1, 2008

By M. C. Ruiz

This work outlines the results of leaching studies on a copper concentrate containing chalcocite (Cu2S) and digenite (Cu9S5) with an acid saline solution of cupric chloride oxygenated at ambient pressure. The variables studied included the stirring speed, concentration of cupric ions, concentration of HCI, concentration of chloride ions, oxygen flow rate, temperature and time. The leaching system was found to be very effective for the dissolution of the concentrate. Over 95% of the copper was dissolved in 30 minutes with negligible dissolution of iron. The dissolution of copper increased with the stirring speed up to about 400 rpm and depended little on the total chloride concentration. The oxygen flow rate affected the dissolution of copper only below 0.1 1/min. The concentration of HC1 did not influence the dissolution providing its was sufficient to avoid the precipitation of copper oxychloride. The study of the effect of the temperature showed a maximum in copper dissolution around 90 "C

Jan 1, 1997

By Adele Garkida

Compacts of crushed waste window glass, fluorescent tubes, drinking glasses and laboratory glass wares were made at various proportions from 106 microns and minus 75 microns powders in combination with 5% bentonite as binder for each glass type, after several trials to determine compatibility of particle sizes. They were made using the uniaxial press at 10,000 psi and sintered at a temperature range of 700- 750oC. The results showed anisotropic shrinkage behavior for all the samples, exhibiting an axial shrinkage lower than the radial shrinkage. Sintered compact from waste drinking glass which comprised of 60% 106 microns and 40% minus 75 microns powders showed the least sintering shrinkage factor of 1.125, fused at 700oC and the highest shrinkage factor of 1.286 obtained at 750oC. This shrinkage behaviour connotes that sintering can be employed to utilize these waste glasses up to the maximum of 95% recycled glass content in ceramic tile production.

Jan 1, 2008

By K. P. V. Lei

The U.S. Bureau of Mines investigated a hydrothermal sulfidation procedure to recover lead and silver from plumbojarosite. The plumbojarosite, generated during pressure-oxidative leaching of zinc concentrate in a commercial operation, contained, in percent, 25.4 pb, 18.8 Fe, 1.4 Zn, 29.5 SO,2-, 3.2 s?, 13.4 total sulfur, and 7.4 oz/ton Ag. The sulfidation was conducted in an autoclave and converted the plumbojarosite to amorphous iron oxide and liberated the lead and silver as sulfides. The best operating conditions were using 50 9 of plumbojarosite and 7 pct s? (2.04 9 S? added) in 500 mL of 2.0 mol/L NH3, 150? C, and 1 h. The sulfidation product contained, in percent, 37 Pb, 28 Fe, 6 S2-, 2 SO,2-, and 11.2 oz/st Ag. Ferric chloride leaching extracted 98 pct Pb and 97 pct Ag from the sulfidation product.

Jan 1, 1990

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 Bart Blanpain, Tom Peter Jones, Muxing Guo, Liugang Chen, Huayue Shi

Fayalite based slag is formed during the smelting process of secondary copper resources. It was found that with the presence of high ZnO, the slag became viscous, causing a slag tapping problem. In the present paper, the phase relations of the slag system ZnO-“FeO”-SiO2-Al2O3- CaO (ZnO = 0-12 wt%, Al2O3% = 0-15 wt%, CaO = 0-1.5 wt%, with iron saturation) at 1150 °C is studied by using quenching technique followed by phase identification and compositional analysis of equilibrated samples. The dependence of FeO and Al2O3 solubility in the liquid slag on the chemical composition of slag is characterized. Based on the experimental data, the solid fraction of the slag, which may considerably, influences the slag viscosity, at the tapping temperature can be reasonably estimated and, therefore an appropriate modification of the slag composition can be made.

Jan 1, 2016

By Robert H. Hsu

Palladium finely dispersed in a substrate of kieselguhr, Pd/k for short, has been successfully used for hydrogen storage, separation and pumping for a number of years at the Savannah River Site (SRS). Recently SRS has developed a new pd/k flow through bed (FTB) prototype for separating hydrogen from other gases and simultaneously storing the hydrogen on palladium. The FTB uses single-pass liquid nitrogen cooling during hydrogen absorption/separation/storage and electrical heating for desorption/unloading of hydrogen. Fourteen absorption-desorption or loading/unloading cycles using hydrogen have been conducted with the new FTB prototype. Test results show that all design performance objectives have been successfully achieved: recover 295% of hydrogen gas from feed gas, produce 99.9% hydrogen product gas and < 5% hydrogen in discharge gas. This paper will discuss characteristics of the palladium-coated kieselguhr or diatomaceous earth, design and operation of the FTB, and results of performance tests such as separation efficiency, hydrogen storage capacity and system heat transfer characteristics.

Jan 1, 2002

By Ray Y. Lin

Chemical vapor deposition of tungsten carbide on the surface of steel has been investigated at temperatures between 400 and 550C in an atmosphere containing tungsten hexafluoride, hydrogen and benzene. The tungsten fluoride flow rate was maintained at 20 ml/min. The hydrogen flow rate was at 100 ml/min. The benzene concentration varied from 1.15 to 5.56% in the reaction gas. It was observed that the higher the temperature, the faster the deposition rate for tungsten carbide. But the dependence of the deposition rate on the benzene concentration was not systematic. From the x-ray diffraction analysis, it was observed that W, W2C and WC are all presented in the coating. The amount of each phase presented in the coating depends on the temperature and, to a less extent, on the benzene concentration. The microhardness measurement has also been done for all CVD carbide coatings obtained in this study.

Jan 1, 1992

By C. J. McKee

A gold-silver-lead-zinc deposit at Montana Tunnels, Jefferson County, Montana is located in a diatreme of middle Eocene age (45 to 50 m.y.). Sulfide minerals within the diatreme occur as disseminations, veinlets, and locally as breccia matrix. Principal sulfide minerals are pyrite, sphalerite, and galena. The diatreme is a matrix-rich quartz latitic breccia with a fine grained rather soft matrix and heterolithic clasts. The ore deposit contains approximately 50 million tons of ore at a grade of 0.025 oz/ton Au, 0.5 oz/ton Ag, 0.25 % Pb, and 0.65 % Zn. Mining is by open pit methods. The original process flowsheet included flotation and cyanide leaching. Problems with the leaching circuit led to a change to the straight flotation process which is presently in use. To maintain a reason-ably uniform feed material, blending of ore is required for grades of four metals as well as for ore hardness and oxidation.

Jan 1, 1988

By Harold R. Kokal

Lisakovsky is a 3-billion ton oolitic iron ore deposit in north-central Kazakhstan operated by Orken LLP, a subsidiary of Ispat Karmet and the LNM Group. The iron oxide minerals are goethite and limonite. The gangue occurs as discrete quartz grains and an unidentified form of colloidal silica-alumina. The concentrate produced contains about 49.5 percent iron (Fe) and 0.6-0.8 percent phosphorus (P) or 10-20 times the acceptable phosphorus level. The phosphorus is intimately associated with the iron oxide and colloidal gangue, no discrete phosphorus minerals are found, and beneficiation is not possible. Therefore, to reduce the phosphorus, a hydrometallurgical process that includes roasting followed by leaching in dilute sulfuric acid has been developed. Phosphorus extraction is 70-90 percent, with only a minor loss of iron. The process has been tested in the laboratory and in a pilot plant at 50-300 kg/h. Construction of a 900,000 t/y demonstration plant is underway.

Jan 1, 2003

By Chai Liyuan

This paper focused on the preparation of porous ceramic pellets for microorganism carriers. A new method for the process was developed using simple gel-casting and bubble-in-water-in-oil type of multiphase double emulsion. The globules, consisting of a foamed sepiolite slurry suspension, were dispersed and consolidated in spherical shape in liquid paraffin as gelation progressed. The green pellets were sintered at 1100°C. The influence of surfactants, extension ratio and impeller revolution rate on the process and characteristics of the pellets was investigated. The pellet size was in the range of 1~4mm and determined directly by impeller revolution rate. The fine cell diameter of porous ceramic was in the range of 100~500m and the micropore diameter was less than 5m. The inner macropores were interconnected and extend to the external surface. It is impossible to analyze a result by SEM micrographs and digital camera.

Jan 1, 2006

By L. Y. Zhang

The current status of metal hydride alloys for NiMH batteries was systematically reviewed. Extensive application-oriented research and development has successfully made the NiMH battery an important part, with growing potential, among rechargeable batteries. The rare earth based metal hydrides (AB5) have been considered the best alloy material for use in the negative electrode in NiMH batteries. However, being in demand for high performance electronic markets, the still young NiMH industry is facing serious technical challenges in developing better products. Among all the efforts to respond to the challenges, advanced AF3, alloys are in great demand: the capacity enhancement race requires new or improved alloys possessing higher volumetric capacity; price competition mandates MH materials with low cost; high performance under severe service environments calls for alloys with high corrosion resistance when subjected to electrochemical cycling; and finally, high power service requires the negative electrode to deliver current at high rates.

Jan 1, 1997

By Vinod K. Namilakonda

In situ synthesis of discontinuously reinforced aluminum alloy metal matrix composites was investigated. Aluminum alloy (A356: Al-7 wt% Si) was reinforced with dispersed AlN particles. Thermodynamic calculations were made for the composition determination of various phases formed during bubbling of NH3 gas into the Al alloy melts in the temperature range 1173-1473 K. Experiments were carried out for in situ production of AlN particles with the reaction between Al melt and NH3 gas in high temperature resistance furnace at 1473 K. The products were characterized using SEM, EDS and XRD. Effect of bubbling time of NH3 gas on the AlN formed in the composites was studied. The amount of AlN reinforcement in the Al alloy composites was observed to be in the range of 5 to 35 wt%. Good agreement was observed between the experimental and thermodynamic calculated data on the composition of AlN in Al alloy composites.

Jan 1, 2006