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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 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 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 G. Scavino

A 0.5 wt.% C, 22 wt.% Mn austenitic steel, recently proposed for fabricating automotive body structures by cold sheet forming, due to favorable overall strength and ductility, exhibits plastic localizations during uniaxial tensile tests, whereas no localization happens during biaxial Erichsen cupping tests. Full-thickness tensile and Erichsen specimens, cut from as-produced sheets, were polished and tested at different strain rates. During the tensile tests, the plastic localization phenomena consist first of macroscopic deformation bands traveling along the tensile axis, and then of series of stationary deformation bands, each adjacent to the preceding ones; both types of bands involve the full specimen width and yield macroscopically observable surface relief. No comparable surface relief was observed during the standard Erichsen tests. The stress state being known to influence plastic localization phenomena, reduced-width Erichsen tests were performed with 10 to 30 mm width polished specimens, in order to explore the transition from biaxial to uniaxial loading.

Jan 1, 2009

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 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

By P. Klut, D. Groult, R. Marechalle, B. T. H. Bonnema

In the past 5 years, Compagnie Europeenne de Dezingage (CED) has developed a successful dezincing process and the St. Saulve pilot plant has evolved into a commercially successful production plant. Currently the plant meets all the required standards for scrap and zinc quality, output capacity, availability, and meets the prescribed environmental emissions standards. The initial process problems relating to zinc recovery, uncontrollable explosions and sodium hydroxide aerosol emissions have all been solved. Presntly, the yearly production of dezinced scrap is around 50.000 tonnes/year; this capacity is enough to supply the local market. This capacity can be increased easily to 65.000 tonnes/year or more. The market for dezinced material is growing due to the increased consumption of galvanized material on one hand and on the other hand the higher demand for high quality scrap. The proven technology of CED is currently patented worldwide, but CED is inviting licensees to implement the dezincing technology in other parts of the world.

Jan 1, 2000

By I. Sofia Fernandez del Rio

This paper describes a process for the treatment of the dusts generated during the operation of blast and reverberatory furnaces in the lead smelter, to remove zinc, cadmium, arsenic and halides from the circuit. The process consists of a Pefloles' developed leaching/purification stage and a solvent extraction process developed by Lurgi. The plant capacity is 5,000 tonnes Zn/year. The feed to solvent extraction contains 8 g/1 Zn. Impurities such as copper, iron, arsenic and cadmium are removed by conventional cementation processes. The cadmium product is 99.99 % pure. The solvent extraction process consists of two extraction stages, one washing stage and two stripping stages. D2EHPA is used as the extraction agent and 25% ammonia as the neutralizer. The rich-zinc solution is sent to the electrolytic zinc plant for zinc recovery. The raffinate produced, which is a mixture of ammonium sulfate and chloride, is used for agricultural applications.

Jan 1, 2000

By Qin Li

An highly active absorbent with oxidization based on fly ash, lime and additives was prepared. Experiments of simultaneous desulphurization and denitrification were carried out using fixture bed and duct injection. The influential factors for the absorptive capacity of the absorbent were studied. The absorptive capacities of 120.7mg for SO2 and 43.7 mg for NOx were achieved at a Ca/(S + N) molar ratio 1.2, respectively, corresponding removal efficiencies of 87% and 76%, while spent absorbent appeared in the form of dry powder. The optimal temperature and humidity of flue gas treated with this process were shown to be approximately 50\\176 and 5% respectively. The mechanism of removal for SO2 and NOx was investigated. In comparison with traditional dry FGD, this process appears to have lower cost, less complicated configuration and simpler disposal of used absorbent. The valuable references can be provided for industrial application by this process. The foreground of application will be vast in China and in the world.

Jan 1, 2006

By P. M. Rosário

The extraction performances exhibited by a phosphoric (D2EHPA), a phosphonic (Ionquest 801), a phosphinic (Cyanex 272) and a dithiophosphinic (Cyanex 301) acid derivative towards indium recovery from a diluted sulfuric solution are evaluated and compared. Equilibrium extraction isotherms were obtained. The chemical reactions involved and the approximate stoichiometry of the In(III) extracted species by the four ligands are presented and discussed. Stripping of In(III) from loaded D2EHPA and Ionquest 801 has been accomplished successfully, but has not been so effective from loaded Cyanex 301. Plots of %E vs. pH were established for D2EHPA, Ionquest 801 and Cyanex 301, denoting their behavior towards the extraction of similar mass concentrations of In(III), Fe(III), Fe(II) and Zn(II). Cyanex 301 is the least selective towards In(III), whereas D2EHPA and Ionquest 801, both for a pH = 0.5, do not extract Zn(II) at all.

Jan 1, 2003

By Pekka Parvinen, Saija Luukkanen, Pentti Pirkonen, Väinö Hintikka, Hannu Sekki

In the study was developed a new method for the treatment soils contaminated by polychlorinated dibenzodioxin and dibenzofuran. The method is based on attrition of soil so that the contaminants absorbed on the particle surfaces are liberated with the fine fraction formed in the attrition process. Same the attrition process produces active surface which can absorb the free contaminants. Before starting the remediation process must be decided the limit value under which the residual concentration must lie. Then in the laboratory is performed an experiment in the base of which is determined the grain size level; material under which much be removed together with the contaminant. In the real sample has been found that after the attrition the limit value 0.5 ng/g (I-TEQ) is obtained when the fine under 0.1mm fraction (20% of the original soils amount) is removed together with the contaminants 96% (original level 10 ng/g; 100%).

Jan 1, 2008

By Taner Kavas

In the present study the utilization of coal ashes that appear at the end of firing process of brick production in cement pastes was examined. Ashes with three different particle sizes of 75 µm, 106 µm and 150 µm were used to replace ordinary Portland cement (PC) as 5 % and 15 % by weight. Seven samples were prepared and physical, mechanical, chemical and microstructural analyses were carried out. The compressive and bending strength values of samples were determined at the ages of 2, 7 and 28 days. It was found that cementitious pastes with finer particle sizes possessed the highest compressive and bending strength values at all curing ages. Both values after 2 and 7 days cure increased with an increase in ash content, no matter what the particle sizes of ashes were. However, strength decreased after 28 days cure as a result of ash addition of 15 %, although it was still above that of the PC.

Jan 1, 2006